Symposium Organizers
Thomas J. Webster Brown University
Huinan Liu University of Pittsburgh
Robert Hurt Brown University
YY1: Gold and Silver Nanoparticles
Session Chairs
Monday PM, November 30, 2009
Room 308 (Hynes)
9:30 AM - YY1.1
Gold Nanoparticles of 1.4 nm Trigger Necrosis by Oxidative Stress and Mitochondrial Damage.
Willi Jahnen-Dechent 1 , Yu Pan 1 , Annika Leifert 2 , David Ruau 4 , Sabine Neuss 7 , Joerg Bornemann 5 , Guenther Schmid 3 , Wolfgang Brandau 6 , Ulrich Simon 2
1 Biomedical Engineering-Biointerface Lab, RWTH Aachen University, Aachen Germany, 2 Inorganic Chemistry, RWTH Aachen University, Aachen Germany, 4 Biomedical Engineering-Cell Biology, RWTH Aachen University, Aachen Germany, 7 Pathology, RWTH Aachen University, Aachen Germany, 5 Electon Microscopy Facility-Medical Faculty, RWTH Aachen University, Aachen Germany, 3 Inorganic Chemistry, University Duisburg-Essen, Essen Germany, 6 Radiochemistry, University Duisburg-Essen, Essen Germany
Show AbstractGold nanoparticles (AuNPs) are generally considered nontoxic like bulk gold, which is inert and biocompatible. Recently however, we showed that AuNPs of 1.4 nm diameter capped with triphenylphosphine monosulfonate (TPPMS), Au1.4MS are much more cytotoxic than 15 nm nanoparticles (Au15MS) of similar chemical composition. Here, we studied major cell death pathways and determined that the cytotoxicity was caused by oxidative stress. Indicators of oxidative stress, reactive oxygen species (ROS), mitochondrial potential and integrity, and mitochondrial substrate reduction were all compromised. Genome wide expression profiling using DNA gene arrays indicated robust up-regulation of stress-related genes after 6 and 12 hours incubation with 2 x IC50 concentration of Au1.4MS, but not with Au15MS nanoparticles. The caspase inhibitor, Z-VAD-fmk did not rescue the cells suggesting that necrosis, not apoptosis was the predominant pathway at this concentration. Pretreatment of the nanoparticles with reducing agents/antioxidants, N-acetylcysteine (NAC), glutathione and TPPMS reduced the toxicity of Au1.4MS. AuNPs of similar size, but capped with glutathione (Au1.1GSH) likewise did not induce oxidative stress. We conclude that beside the size dependency of AuNP toxicity, ligand chemistry is a critical parameter determining the degree of cytotoxicity. AuNP exposure likely causes oxidative stress that is amplified by mitochondrial damage. In summary Au1.4MS nanoparticle cytotoxicity is associated with oxidative stress, endogenous ROS production and depletion of the intracellular antioxidant pool.
9:45 AM - YY1.2
On the Slow Dissolution of Gold Nanoparticles in Aqueous Media.
Dirk Mahl 1 , Matthias Epple 1
1 Inorganic Chemistry, University of Duisburg-Essen, Essen Germany
Show AbstractGold nanoparticles are important in cancer diagnostics and cancer therapy. Due to their small size (1 to 200 nm), they are able to penetrate a cell membrane. The biological action of such nanoparticles depends on their size and shape. However, the fate of gold nanoparticles within a biological system is still largely unknown, and questions also remain regarding the different actions of gold ions and nanoparticles. Therefore, the solubility of these nanoparticles in biological systems is of high interest to understand which reactions are occurring inside cells. We have measured the release of gold ions from dispersed gold nanoparticles in different aqueous media. Our intention was to measure the equilibrium concentration of gold ions above the surface of these corresponding nanoparticles in different aqueous media. A well-defined amount of nanoparticles was dispersed in ultra-pure water and stored under constant stirring. In defined intervals, aliquots were taken. The gold nanoparticles were separated from the corresponding ions by dialysis, ultracentrifugation and/or nanofiltration. This procedure should exclude any nanoparticles that could still be present. All samples which were taken have been analyzed by inductively coupled plasma mass spectrometry (ICP-MS). A slow dissolution (i.e. an oxidation of the metal) was observed which probably also occurs in biological environments.Gold nanoparticles were prepared by the reduction of tetrachlorogold acid with sodium citrate with an average size of 18 nm [1]. The nanoparticles were stabilized by the ligand tris-metasulfonatophenylphosphine [2] or the polymer poly(vinylpyrrolidone), PVP. All nanoparticles were fully characterized by dynamic light scattering (DLS), electron microscopy (SEM, HRTEM), and spectroscopy (IR, UV-Vis).[1] J. Turkevich, P.C. Stevenson, J. Hilliery, Discuss Faraday Soc., 11 (1951), 55.[2] G. Schmid, A. Lehnert, Angew. Chem. Int. Ed., 28 (1989), 780.AcknowledgementsWe thank Prof. M. Farle (University of Duisburg-Essen) and Prof. M. Vallet-Regi (Universidad Complutense Madrid) for help with transmission electron microscopy and Prof. A. V. Hirner (University of Duisburg-Essen) for help with the analysis of the gold samples by inductively coupled plasma mass spectrometry.
10:00 AM - YY1.3
RF Controlled Release of Intracellular Gold and Silver Nanoparticle Conjugates for Use as Potential Sensors or Modulators for Biological Function.
Richard Murdock 1 , Omar Khan 1 , Christin Grabinski 1 , Laura Stolle 1 , Saber Hussain 1
1 Applied Biotechnology Branch, Human Effectiveness and Protection Directorate, Air Force Research Laboratory, Dayton, Ohio, United States
Show AbstractThe objective of this investigation was to further explore the ability of noble metal nanoparticles to respond to oscillating electric fields and their ability to produce unique local surface plasmon resonance (LSPR) responses for the purpose of acting as an intracellular labeling method to visualize cellular dynamic structures as well as the potential to modulate biological function. In this study, 4nm (3.88±1.14 nm) gold nanoparticles (Au NPs) and 7nm (7.37±3.94 nm) silver nanoparticles (Ag NPs) were synthesized via a sodium borohydride reduction of gold (III) chloride trihydrate and silver nitrate, respectively. Particles were characterized in dried form under transmission electron microscopy (TEM), and in solution, via UV-Vis spectroscopy (4nm Au: Amax: 503nm, 7nm Ag: Amax: 390nm) and dynamic light scattering (DLS). The Au and Ag NPs were separately functionalized with complementary thiol-modified oligonucleotide sequences and then hybridized to form larger Au or Ag NP aggregates. Melting point analysis was completed via UV-Vis and DLS to verify proper functionalization and hybridization of the particles. The complementary oligonucleotides allowed Au-Ag NP hybridized complex to be formed. Once exposed and internalized by the cells, radio frequency (RF) signals in the high to ultra high frequency ranges (10 to 400 MHz range) were used to heat and dehybridize the Au-Ag complexes. Dehybridization of the Au-Ag NP complexes and localization of the nanoparticles to the correct cellular structures was confirmed using the hyperspectral imaging system as well as fluorescent antibody staining of the cellular structures. Biocompatibility of the functionalized particles was conducted to verify that particles were not interfering with normal cell processes or causing detrimental effects. Biocompatibility of the unfunctionalized particles, functionalized particles and hybridized particles was conducted by exposing the particles to human keratinocytes (HaCat) cells. Based on the toxicity studies, no significant toxicity effects were observed from either the unfunctionalized or functionalized particles. In conclusion, this study shows that noble metal nanoparticles demonstrated remarkable properties under RF stimulation and possess unique LSPR responses which can be exploited once biofunctionalized and placed in a biological system. Further studies are underway to examine if functionalized nanoparticles could be used potentially as intracellular sensors or modulators of biological function.
10:15 AM - YY1.4
Synthesis of PVP-functionalized Silver Nanoparticles and Their Biological Activity Towards Human Mesenchymal Stem Cells.
Joerg Diendorf 1 , Stefanie Kittler 1 , Christina Greulich 2 , Manfred Koeller 2 , Matthias Epple 1
1 Institute of Inorganic Chemistry and Center for Nanointegration Duisburg-Essen (CeNIDE), University of Duisburg-Essen, Essen, NRW, Germany, 2 Department of Surgery, Surgical Research, University Hospital Bergmannsheil, Bochum, NRW, Germany
Show AbstractThe properties of nanoparticles and their effects on biological systems are of great interest in actual research. Mechanisms, rates and effects of the interactions between (silver) nanoparticles and biological systems depend on a number of nanoparticle properties including size, shape, morphology, charge and surface functionalities. Due to the well-known antibacterial properties of silver and silver ions [1,2] we studied the effects of PVP-functionalized silver nanoparticles on human mesenchymal stem cells (hMSC) as a model system. It is generally assumed that macroscopic silver as well as the nanoparticles release silver ions which are the biologically active agent. Moreover, in the case of nanoparticles, the uptake of the whole particle into a living cell is possible and the constituting ions will be released inside the cell [3].Silver nanoparticles were prepared by the polyol process [4], i.e. by the reduction of silver nitrate with ethylene glycol in the presence of polyvinylpyrrolidone (PVP). Thereby, the silver nanoparticles were colloidally stabilized by the polymer. The synthesis of nanoparticles of different size and shape (cubes, rods and spheres) was possible by changing the reaction conditions such as reagent ratio and temperature. The silver nanoparticles were characterized by dynamic light scattering (DLS), zeta-potential measurements, UV-spectroscopy, and scanning electron microscopy (SEM). The biological activity of spherical PVP-functionalized silver nanoparticles with a diameter of about 100 nm was tested on human mesenchymal stem cells in comparison with equivalent amounts of silver ions (silver acetate). The stem cells were treated with silver concentrations in the range of 50 ng mL-1 to 50 µg mL-1 for 7 days under cell culture conditions. Cytotoxic cell reactions were observed at ≥ 2.5 µg Ag mL-1 for nanoparticles and ≥ 1 µg Ag mL-1 for silver acetate, indicating a critical role of the silver ions for toxic reactions.[1]A. D. Russell, F. R. C. Path, F. R. Pharm, W. B. Hugo, Pharm. Progr. Med. Chem. 1994, 31, 351.[2]D. W. Brett, Ostomy/wound management 2006, 52, 34.[3]S. Y. Liau, D. C. Read, W. J. Pugh, J. R. Furr, A. D. Russell, Lett. Appl. Microbiol. 1997, 25, 279.[4]S. H. Im, Y. T. Lee, B. Wiley, Y. Xia, Angew. Chem. Int. Ed. 2005, 117, 2192.
11:00 AM - **YY1.5
Human Mesenchymal Stem Cell Responses on Novel Biologically Inspired Nanocomposites.
Lijie Zhang 1
1 , University of California, Davis, California, United States
Show AbstractVarious bone and articular cartilage defects, caused by trauma, disease or age-related degeneration, represent a crucial clinical problem all over the world. However, traditional implant treatments may cause many complications after surgeries, leading to intense patient pain. Thus, the objective of this in vitro study was to design novel biomimetic nanocomposites based on hydroxyapatite (HA), rosette nanotubes (RNTs), tricalcium phosphate (TCP) and collagen and investigate human mesenchymal stem cell (MSCs) responses towards these nanocomposites for bone, cartilage and osteochondral tissue regeneration. As promising progenitor cells for tissue regeneration, MSCs can self renew and differentiate into multiple cell types such as osteoblasts, chondrocytes and endothelial cells, which make them excellent candidates for restoring damaged bone or cartilage. In addition, RNTs are a class of biologically inspired nanomaterials obtained through the self-assembly of DNA motifs in aqueous solutions and have shown excellent cytocompatibility properties for bone repair. Specifically, this study demonstrated for the first time that HA/TCP/collagen/RNT nanocomposites induced greater alkaline phosphatase activity than HA/TCP/collagen and collagen controls after 21 days. In addition, results showed that HA/TCP/collagen/RNT nanocomposites had higher amounts of alkaline phosphatase activity than HA/TCP/RNT without collagen after 7 days of culture. Furthermore, increasing amounts of calcium deposition were observed on biomimetic HA/TCP/collagen/RNT, HA/TCP/RNT nanocomposites and HA/TCP/collagen as well as HA/TCP composites when compared to collagen controls. In summary, this study indicated that such novel nanocomposites with biomimetic ceramics, collagen and nanotubes are cytocompatible for mesenchymal stem cells and can promote osteogenic differentiation of MSCs, thus, they hold great potential for bone, cartilage and osteochondral tissue engineering applications.
11:30 AM - YY1.6
Investigation of Mechanisms for Microbial Rejection from Silver Ion Implanted Surfaces of Biocompatible Materials.
Patrice Coleman 1 , Tomeka Colon 1 , Malek Abunaemeh 1 , Ibidapo Ojo 1 , Claudiu Muntele 1 , Robert Zimmerman 1 , Daryush Ila 1
1 , Alabama A&M University, Normal, Alabama, United States
Show AbstractWe studied the chemical interaction of implanted silver ions in nanostructured glassy polymeric carbon artifacts with water in order to understand the mechanisms of microbial rejection of silver treated biocompatible materials. Previous work has shown a clear silver distribution dependence of cell tissue adhesion on such surfaces. All cell cultures were in an aquaeous medium, and other research has speculated that the microbiotic rejection is due to silver’s ability of changing the water molecules into hydrogen peroxide through a catalytic action. Hydrogen peroxide is a well known antimicrobial agent and is frequently used as a disinfectant for common skin lesions. Knowing the exact mechanism of cell rejection is of crucial importance in designing materials with controllable biological tissue adhesion for medical prosthetics and drug/medication delivery ports. We implanted 5 MeV silver ions into glassy polymeric carbon using the ion accelerator at the Alabama A&M University. We used Rutherford Backscattering Spectrometry for determining the exact silver distribution inside the material and surface silver concentration, and Raman spectroscopy for investigating the chemical interaction of surface silver atoms with water drops. We were able to quantify chemical changes as a function of surface silver concentration and substrate temperature in the 15 to 40 deg C temperature range.
11:45 AM - YY1.7
Universal Correlation and Mechanism for the Antibacterial Activity of Silver Nanoparticles.
Georgios Sotiriou 1 , Adrian Camenzind 1 , Andreas Meyer 2 , Frank Krumeich 3 , Sven Panke 2 , Sotiris Pratsinis 1
1 Mechanical and Process Engineering, Particle Technology Laboratory, Zurich Switzerland, 2 Biosystems Science and Engineering, Bioprocess Laboratory, Basel Switzerland, 3 Chemistry and Applied Biosciences, Laboratory of Inorganic Chemistry, Zurich Switzerland
Show AbstractUncoated and SiO2-coated Ag/SiO2 nanoparticles were made by flame spray pyrolysis (FSP) of a Ag nitrate and hexamethyldisiloxane (HMDSO) containing solution. The product particles were characterized by STEM/TEM, EDX spectroscopy, X-ray diffraction, N2 absorption (BET) and O2 chemisorption. The Ag clusters exhibited a bimodal distribution as determined by microscopy and XRD. The conductivity of aqueous solutions containing the uncoated Ag/SiO2 nanoparticles was measured as well as their antibacterial activity against the Gram negative bacterium Escherichia coli. Low Ag-content particles had more exposed Ag surface area. The antibacterial performance of Ag/SiO2 nanoparticles was determined solely by the exposed Ag surface area in the solution over a wide range of particle concentrations and Ag-content. Additionally, by hermetically coating the Ag nanoparticles by a SiO2 layer, controllability over the antibacterial activity can be established. Finally, Ag ions rather than Ag nanoparticles determine the antibacterial performance of the Ag/SiO2 nanoparticles, as it was shown by monitoring bacterial growths in solutions containing similar Ag+ ions concentrations, in the presence and absence of Ag nanoparticles.
12:00 PM - **YY1.8
Surface Modification of Iron Oxide Nanocrystals for Biological Applications.
Y. Wang 1 , Zoraida Aguilar 1 , Hengyi Xu 1 , Hui Mao 2 , Xiaohu Gao 3 , Lily Yang 2
1 , Ocean Nanotech, LLC, Springdale, Arkansas, United States, 2 , Emory University, Atlanta, Georgia, United States, 3 , University of Washington, Seattle, Washington, United States
Show AbstractIron oxide nanocrystals with high magnetization and well controlled size and surface chemistry are currently under intense study due to their broad applications in biomedical research, such as magnetic resonance imaging (MRI), bio-separation, hyperthermia therapy, and drug delivery. Recent advances in iron oxide nanocrystals synthesized at elevated reaction temperatures allows for the preparation of monodisperse particles within a size range of 4-50 nm. However, the hydrophobic nature of the iron oxide nanocrystals prevents their use in biomedical applications. Several approaches to convert this new generation of iron oxide nanocrystals to water soluble nanocrystals have been developed. Each method has its own strengths and weakness. However, common requirements of water soluble nanocrystals for biological applications are high stability, less non-specific binding, less RES uptake for in vivo applications, and less toxicity from the original surface coating. In this talk, we will present Ocean’s progress in the synthesis of iron oxide nanocrystals in the size range of 5-50 nm, surface modification with superior colloidal stability, and various multi-functional groups for flexible bioconjugation schemes. We will also report our recent results in MRI imaging, drug delivery and bio-separation using the size tunable iron oxide nanoparticles.
YY2: Carbon-based Nanomaterials
Session Chairs
Monday PM, November 30, 2009
Room 308 (Hynes)
2:30 PM - **YY2.1
Potential Human Health Impacts of Nanotechnology.
Agnes Kane 1 , Robert Hurt 1
1 Pathology and Laboratory Medicine, Brown University, Providence, Rhode Island, United States
Show AbstractNanotechnology has been described as the next industrial revolution. Approximately 600 commercial nanoproducts are already on the market. Many more novel applications are anticipated in electronics, energy, nanoengineered devices, environmental remediation, and nanomedicine. Nanomaterials are defined as engineered materials with a least one dimension in the range of 1-100nm. Engineered nanomaterials have unique chemical and physical properties compared with micron-sized or bulk materials. Some nanomaterials have been shown to have highly reactive surfaces that may induce toxicity upon interaction with biological systems; however, predicting the exact properties of these materials that may be linked with adverse environmental and human health impacts is technically challenging. Identification of specific chemical and physical properties of nanomaterials responsible for cellular toxicity will enable development of manufacturing methods and post processing steps to eliminate intrinsic toxicity. Physical and chemical properties of asbestos fibers and carbon nanotubes relevant for toxicity include fiber length, bioavailable metals, and biopersistence. This interdisciplinary research collaboration establishes interim nanosafety precautions for research in nanotechnology based on administrative, personal protection, and engineering controls to avoid inhalation or dermal exposure. Some nanomaterials pose additional safety concerns related to chemical catalytic and explosive properties. This research was supported by a Superfund Basic Research Program Grant (NIEHS P42 ES013660), an NSF NIRT Grant (DMI-050661), an NIH Grant R01 ES016178, and an EPA Grant (RD-83386201).
3:00 PM - YY2.2
Internalization Mechanisms of Nanodiamonds is Dependent Upon Surface Functional Groups.
Robert Lam 1 , Xueqing Zhang 1 , Mark Chen 1 , Dean Ho 1
1 , Northwestern University, Evanston, Illinois, United States
Show AbstractSeveral previous reports have detailed the relationship between size, surface functionalization and internalization for a variety of nanoparticles (gold, silver, polymer, etc). Nanodiamonds (NDs) in particular have recently been implicated in a variety of biomedical applications. Among these, the most promising are utilizing NDs as drug delivery carriers, imaging agents and for the entrapment of proteins. In several of these applications, the successful internalization of NDs is of utmost importance. However, the internalization mechanisms and cellular response of NDs have thus far not been reported.Towards this, we investigated cellular internalization with ND surfaces functionalized with carboxyl (CNDs) and amine groups (NH2-NDs). Originally purchased NDs were carboxylated. By covalently attaching (3-aminopropyl) trimethoxysilane, resultant NH2-NDs were processed and characterized with dynamic light scattering analysis. Surface functionalization is critical not only for binding of ensuing biological agents, but also for interactions with the plasma membrane. It has been previously hypothesized that positively charged particles interact more ably with the plasma membrane's negatively charged protein surface. For example, positive ND surfaces would theoretically allow for better DNA complexing, and better transfection. The aforementioned NDs were tagged with rhodamine and fluorescein isothiocyanate (FITC) for fluorescence microscopy identification. Based on the duration of incubation and subsequent chemical modification, the NDs were shown to localize within different regions and have various internalization efficiencies based on time and concentration. For example, preliminary results have revealed that CNDs successfully internalize within two hours in HeLa cells while NH2-NDs remained bound to the membrane, possibly due to the antecedent electrostatic nanoparticle-membrane interactions. Further discussion examines the ND fate as a result of subcellular localization, such as endosome destabilization. The association between kinetics and internalization will be further explored by comparing flow cytometry results of the amount of NDs attached to the membrane and the number of NDs localized within the cell, achieved via trypan blue fluorescence quenching properties. Lastly, the cytoxicity of each functionalized ND is examined and compared.
3:15 PM - YY2.3
The Impact of Substrate Topography on Cell Filopodia Extension and Cell Spreading.
David Stout 2 1 , Lei Yang 1 , Thomas Webster 1
2 , California State University, Long Beach, Long Beach, California, United States, 1 , Brown University, Providence, Rhode Island, United States
Show AbstractCell spreading on substrates affects subsequent cell functions, including proliferation and differentiation. Also, cell spreading is directly related to filopodia extension on different substrate topographies. To better understand this correlation, live-cell imaging was used in the present study to investigate osteoblast (bone forming cell) and fibroblast filopodia extension and subsequent cell spreading on two different kinds of diamond. Nanocrystalline diamond (NCD) and submicron crystalline diamond (SMCD) were fabricated to possess similar surface chemistry but different topographies, consisting of nanoscale spherical grains in NCD and submicron polyhedral grains in SMCD. The filopodia extension and cell spreading results showed that cells on nanoscale topographies extended filopodia faster and had greater expansion area than on submicron topographies. Results indicated that substrate topography had an impact on cell filopodia extensions and cell spreading and NCD promoted filopodia spreading and cell expansion better than SMCD, thus, providing key information concerning how to control such events on implant surfaces.
3:30 PM - **YY2.4
Carbon Nanotube Field Emission Nanotechnology Based Multi-pixel X-ray Source for Biomedical Applications.
Sigen Wang 1 2 , Xiomara Calderon-Colon 2 , Rui Peng 2 , Otto Zhou 2 3 , Sha Chang 1
1 Department of Radiation Oncology, University of North Carolina, Chapel Hill, North Carolina, United States, 2 Department of Physics and Astronomy, University of North Carolina, Chapel Hill, North Carolina, United States, 3 Lineberger Comprehensive Cancer Center, University of North Carolina , Chapel Hill, North Carolina, United States
Show AbstractIn this presentation, we report on the design and fabrication of carbon nanotube field emission nanotechnology based multi-pixel x-ray source for biomedical applications. X-rays are widely used for radiation therapy and diagnostic imaging. They are conventionally generated by a vacuum tube (x-ray tube) that uses a high voltage to accelerate electrons produced by thermionic emission to a high velocity. The electrons collide with a metal anode (tungsten or molybdenum), thereby generating x-rays. In contrast, nanotechnology x-rays are based on nanostructure (carbon nanotube) field emission which is associated with a quantum mechanical tunneling process whereby electrons tunnel through a potential barrier under the influence of a high electric field. The electrons emitted from the carbon nanotubes are accelerated and bombard a metal anode (tungsten or molybdenum) to produce x-rays. The advantages of nanotechnology based x-ray sources over conventional thermionic x-ray sources are as follows: significant miniaturization of the x-ray sources, production of focused electron beams with very small energy spread and programmable pulse width and repetition rate, elimination of heating that would be required for x-ray generation in thermionic sources, instantaneous control and modulation of the emission current by electronics, and fabrication of matrix addressable multi-pixel x-ray sources with high temporal and spatial resolution. The use of this novel multi-pixel x-ray technology for micro-radiotherapy device development for cancer research is also discussed.
YY3: Polymeric Nanomaterials
Session Chairs
Monday PM, November 30, 2009
Room 308 (Hynes)
4:30 PM - **YY3.1
Nanoengineering of Immune Cell Function.
Lance Kam 1
1 , Columbia University, New York, New York, United States
Show AbstractT lymphocytes are a key regulatory component of the adaptive immune system. Understanding how the micro- and nano-scale details of the extracellular environment influences T cell activation may have wide impact on the long-term performance of materials. This talk focuses on the activation of CD4+ T cells in response to such factors. In particular, we examine how the micro- and nano-scale presentation of activating ligands influences activation of T cells, focusing on cytokine secretion and proliferation as key measures of T cell function. Nanoscale mobility of activating ligands is captured in these systems using a supported lipid bilayer model. We extend these studies to include the role of cell-generated forces, and the rigidity of the microenvironment, on T cell activation. The direct and indirect impacts of nanoscale topologies on T cell activation influence the overall strength of the immune response.
5:00 PM - YY3.2
Protein-Nanoparticle Conjugates as Potential Therapeutic Agents for Treatment of Hyperlipidemia.
Victor Maximov 1 , Vladimir Reukov 1 , Caterine Cochrane 2 , John Barry 1 , Alexey Vertegel 1
1 Bioengineering, Clemson University, Clemson, South Carolina, United States, 2 , Governor's School for Science and Mathematics, Hartsville, South Carolina, United States
Show AbstractAtherosclerosis is the primary cause of heart disease and stroke in Western societies. Hyperlipidemia, an excessive amount of low density lipoproteins (LDLs) in the circulation, is a known risk factor for atherosclerosis. This condition is associated with the lack of LDL-receptors in hepatocytes, which consequently cannot uptake an adequate amount of LDLs, inhibiting further metabolism of “bad” cholesterol located in LDLs. Current strategies to treat hyperlipidemia include treatment by statins, which increase the uptake of dietary cholesterol carried by LDLs. In spite of proven benefits to the patients, such treatments can lower LDL counts by only 30 to 50%, which in most cases leaves the cholesterol level higher than the desirable 60-70 mg/dL. This necessitates development of new strategies for reducing excessive LDL levels.We propose a novel strategy for enhanced delivery of LDLs to the liver. Polymeric nanoparticles are known to be actively taken up by Kupffer cells in the liver with a half life of ~10 minutes. We use a monoclonal antibody specific to a major LDL component, human apolipoprotein B-100 (apoB), covalently attached to biocompatible polylactide nanoparticles (PLA). It can be expected that antibody-coated nanoparticles will adsorb LDLs while in circulation and then directed to the liver via uptake by Kupffer cells. This will provide alternative pathway for LDLs to the liver for patients with lack of LDL receptors. Kupffer cells attempt to digest the uptaken material by directing it to lysosomes, thus providing a biochemical pathway similar to that for normally processed LDLs.Here we performed in vitro proof-of-concept experiments to test the proposed strategy. ApoB antibody was covalently attached to 150 nm PLA nanoparticles using a heterobifunctional sulfo-HSAB crosslinker. Binding yield was quantified using fluorescently labeled antibody. Solution of LDLs (500 mg/dL) in PBS buffer with 2% bovine serum albumin was used as a model for high cholesterol human plasma. This solution was titrated with nanoparticle-antibody conjugates. After each titration step, the suspension was centrifuged at 3,000 g to precipitate only nanoparticles, but not unbound LDLs, from the suspension. The concentration of LDLs in the supernatants was measured using Amplex Red Cholesterol Assay Kit. Over five titrations, we were able to decrease the LDL concentration from 500 mg/dL to 80 ± 10 mg/dL (more than 6-fold).The in vitro study of uptake of LDL-apoB-PLA complexes was performed using the mouse macrophage cell line (RAW 264.7) as a model of Kupffer cells. Fluorescent imaging demonstrated that macrophages uptake and digest LDL-apoB-PLA complexes within 4 hours. No dead cells were detected in cultures up to 48 h post-treatment.In conclusion, the proposed antibody-nanoparticle conjugates could be a promising therapeutic approach for effective removal of excessive LDLs from the circulation.This work was supported by Clemson Research Council grant.
5:15 PM - YY3.3
Conjugation of Lysostaphin to Polylactide Nanoparticles Results in its Enhanced Activity Against S. aureus in vitro.
Rohan Satishkumar 1 , Alexey Vertegel 1
1 Bioengineering, Clemson University, Clemson, South Carolina, United States
Show AbstractStaphylococcus aureus is an opportunistic Gram-positive pathogen capable of causing a wide range of infections. Currently, there is a constant need for new antistaphylococcal therapeutics due to the development of antibiotic-resistant strains. Use of enzymes as antimicrobial agents is inspired by nature and has recently attracted much attention as an antibiotic-free approach to treat bacterial infections. Lysostaphin is an antibacterial enzyme which specifically cleaves cross-linked pentaglycine bridges in the peptidoglycan of S. aureus, hydrolyzing the cell wall and killing the bacteria. The use of such antibacterial enzymes attached to biodegradable and biocompatible polymer nanoparticles is of special interest because of enhanced stability of enzyme-nanoparticle conjugates and the possibility of targeted delivery. We have previously demonstrated charge-directed targeting of a model antibacterial enzyme, Hen-egg lysozyme attached to positively-charged polystyrene latex nanoparticles [1]. Here, we studied the antibacterial activity of a more clinically relevant enzyme, lysostaphin, attached to 200 nm polylactide (PLA) nanoparticles. Effect of co-immobilization of a targeting antibody (rabbit polyclonal anti-S. aureus IgG) was also studied. Monodisperse PLA nanoparticles were synthesized using an oil/water emulsion method based on solvent diffusion using Pluronic F68 as a surfactant. Adsorption of AlexaFluor 594-labeled lysostaphin with or without AlexaFluor 360-labeled S. aureus antibody to PLA nanoparticles was studied at different concentrations and enzyme:antibody ratios. Binding yield for enzyme and antibody was calculated from fluorescence intensities of initial suspension, supernatant and redispersed pellet, and consisted of 40-50% and 10-25 % for enzyme and antibody respectively, for a wide range of enzyme and antibody concentrations. Enzyme-(antibody)-nanoparticle conjugates were characterized with a particle size analyzer using DLS and direct visualization of the conjugates was done using atomic force microscopy. We found that protein adsorption did not result in a significant aggregation of nanoparticles. At least a three-fold increase in the rate of S. aureus degradation was observed in the case of enzyme-nanoparticle conjugates as compared to that of the free enzyme at the same concentration(p<0.05). We hypothesize that the greater activity of enzyme-nanoparticle conjugates is due to their more effective binding to bacteria through multiple enzyme molecules attached to a nanoparticle. Presence of the antibody did not significantly affect the rate of the S. aureus degradation, suggesting that lysostaphin binding plays critical role in the process of bacterial lysis. Such enzyme-nanoparticle conjugates have potential for becoming novel therapeutic agents for treatment of antibiotic-resistant S. aureus infections. References 1.Satishkumar R and Vertegel A, Biotechnol. Bioeng., 100(3) (2008), 403-412
5:30 PM - YY3.4
Alginate Based Microparticle Drug Delivery Systems for the Treatment of Eye Cancer.
Yerkesh Batyrbekov 1 , Dinara Rakhimbaeva 2 , Kuanyshbek Musabekov 2 , Bulat Zhubanov 1
1 Polymer, Institute of Chemical Sciences, Almaty Kazakhstan, 2 , Kazakh State University, Almaty Kazakhstan
Show AbstractAlginate based microparticle drug delivery systems were prepared for the sustained release of antitumor drugs. Two drugs, cyclophosphane and 5-fluorouracil, were encapsulated into the microparticles. The drug loaded microparticles were fabricated using a very convenient method under very mild conditions by the gelation of alginate with calcium cation. Modified microparticles were obtained by syringed dropwise a solution of drugs in sodium alginate into chitosan solution in calcium chloride. The effect of polymers concentration and the drug loading (1.0, 5.0 and 10%) on the release profile of drugs were investigated. The amount of drug release was much higher initially (approximately 25%), followed by a constant slow release profile. All the release data show the typical pattern for a matrix controlled mechanism. The cumulative amount of drug released from alginate gels was linearly related to the square root of the time and the release rate decreased this time. The process is controlled by the diffusion of antitumor drugs through the chitosan coating. Scanning electron microscopy (SEM) and particle size analysis revealed differences between the formulations as to their appearance and size distribution. The experiments for anticancer action of alginate microparticles were determined at 120 inbreeded white rats (females, weight 120-125 g, age 2-3 month) infected by malignant Rhabdomyoma strain at the dose of 10 000 cells. Medical-biological tests show that the duration of anticancer activity for the drug-containing alginate microparticles increases at 5-8 times in comparison of free drugs. Such systems may have potential for controlled delivery of antitumor drugs for the treatment of eye cancer.
Symposium Organizers
Thomas J. Webster Brown University
Huinan Liu University of Pittsburgh
Robert Hurt Brown University
YY4: Oxide Nanoparticles I
Session Chairs
Tuesday AM, December 01, 2009
Room 308 (Hynes)
9:30 AM - YY4.1
Radiolabelling of TiO2 Nanoparticle Libraries for Toxicological Investigations.
Anthony Musumeci 1 , Lawrence Gahan 2 , Darren Martin 1 , Tijana Rajh 3 , Suzanne Smith 4
1 Australian Institute for Bioengineering and Nanotechnology, The University of Queensland, Brisbane, Queensland, Australia, 2 School of Molecular and Microbial Sciences, The University of Queensland, Brisbane, Queensland, Australia, 3 Center for Nanoscale Materials, Argonne National Labs, Chicago, Illinois, United States, 4 Institute for Materials Engineering, Australian Nuclear Science and Technology Organisation, Menai, New South Wales, Australia
Show AbstractTitanium dioxide (TiO2) nanoparticles have a multitude of applications including photocatalysis, cancer therapy, cosmetics and sunscreens. This diverse range of applications is due to their size dependent chemical properties. Although used in a number of consumer products, little is understood about their biological interactions and toxicity. Such biological responses may be dependent on the surface chemistry of a nanoparticle, in addition to the size, shape, and chemical composition. Our ability to predict the relationship between physical and chemical parameters and biological systems has proven to be a very complicated and challenging assignment to-date. To further our understanding of nanoparticle interactions with biological systems, it is important that we develop highly sensitive, reliable and robust methodologies to label these nanoparticles. It is essential that in designing these labelling techniques we can demonstrate the label is stable and that the native physical and biological characteristics of the nanoparticles are not altered. Furthermore, that we use these labelling techniques to monitor their transport and interactions in typical but realistic environments.Radioisotopic labelling offers unparalleled detection sensitivity and compatibility with nanoparticle synthesis methodologies. We have demonstrated enediol molecules (i.e. dopamine, dopac) can be readily attached to the metal oxide TiO2 nanoparticle surface [1]. For this study we were interested to investigate the use of these enediol molecules as linker sites for conjugation two bi-functional ligands (1-N-(4-aminobenzyl)-2,6,10,13,16,19-hexaazabicyclo[6.6.6]eicosane-1,8-diamine (N6SarAr) and N-(4-aminobenzyl)-1-methyl-3,12,16-trithia-6,10,19-triazabicyclo[6.6.6]icosan-8-amine (N3S3SarAr) to a range of TiO2 nanoparticles (nanospheres, nanotubes and nanorods). Both the N6 and N3S3 SarAr type ligands are known to form complexes Co2+ and Cu2+ that are thermodynamically and kinetically stable at micro-molar concentrations (10-6 M) [2]. The effect of the concentration of various linkers, bi-functional chelators and pH were investigated in order to optimise the radiolabelling of each type of TiO2 nanoparticle. Efficiency of radiolabelling was dependent on size and shape of TiO2 nanoparticles as well as pH. Furthermore, the radiolabelled the TiO2 nanoparticles show good stability over a range of pH. The radiolabelling method outlined shows great versatility over a range of different TiO2 nanoparticle sizes and shapes and has the potential to be used to monitor the toxicity of these materials in their biological environments. References:[1] A. W. Musumeci, D. Gosztola, T. L. Schiller, N.M Dimitijevic, V. Mujico, D. J. Martin, T. Rajh, (2009), J. Am. Chem. Soc., 131, 6040-6041. [2] Di Bartolo, Nadine M.; Sargeson, Alan M.; Donlevy, Therese M., Smith, Suzanne V. J. Chem. Soc., Dalton Transactions (2001) 15: 2303-2309.
9:45 AM - YY4.2
TiO2, SiC Nanoparticles Toxicological Impact in vitro.
Nathalie Herlin Boime 1 , Mary Line Jugan 2 , Simon-Deckers Angelique 2 , Yann Leconte 1 , Cecile Reynaud 1 , Marie Carriere 2
1 IRAMIS/SPAM, CEA, Gif/Yvette Cedex France, 2 IRAMIS/SIS2M, CEA, Gif/Yvette France
Show AbstractThe development of nanotechnologies may lead to considerable release of nanomaterials in the environment, that can be potentially toxic for human health and environment. Inhaled nanomaterials might cause damage to respiratory tract, particularly to the alveolar compartment. In this context, our research is focused on the response of eukaryotic cells, in vitro, to nanomaterial exposure. For this purpose, we used models of primary target organs (lung, A549 alveolar epithelial cells), or secondary target organs (liver, Hep-G2, WIF-B9, Can-10 and kidneys, NRK-52E, LLC-PK1), i.e. organs exposed if nanomaterials are translocated through epithelial barriers. These cells were exposed to TiO2 or SiC nanoparticles from commercial origin, or synthesized in the laboratory which allows good control of size and cristallinity of the nanoparticles. A549 were exposed to five different TiO2 nanoparticles which were previously shown to be internalized in these cells, as well as to six different SiC nanoparticles. Cytotoxicity was assessed by MTT and LDH assays. Reactive oxygen species generation was evaluated. The alkaline comet assay, gamma-H2AX immunostaining and micronucleus tests were used to evaluate nanomaterials genotoxicityOur data demonstrate that nanoparticles toxicity depends on their size, morphology and chemical composition. The smallest nanoparticles (diameter 10-25 nm) and the spherical ones induced toxic effects whereas particles with diameter superior to 100 nm and elongated ones did not. Toxicological effects of TiO2 nanoparticles were more important than that of SiC nanoparticles Cell death only reached 25-30% of cell population after 48 h of exposure to 50-200 µg/ml nanoparticles. These nanomaterials were rapidly accumulated in cells, probably by endocytosis. TiO2 nanoparticles were responsible for reactive oxygen species generation in exposed cells. However they did not induce the activation of oxidative stress regulation systems (superoxide dismutase, catalase, glutathione peroxidase, glutathione reductase) and total glutathione level remained stable in exposed cells. Genotoxic effects were detected via the alkaline comet assay after 24 and 48 h of exposure of A549 to TiO2 nanoparticles, but neither micronuclei nor double strand breaks were induced. One originality of this study lies on the panel of well characterized nanomaterials which were tested on the same cell line with several methods. These data lead to a better understanding of nanomaterial cytoxicity and a better learning about the undergoing mechanism of genotoxicity.
10:00 AM - YY4.3
The Effect of Titanium Dioxide and Zinc Oxide Nanoparticles on Different Types of Human Skin Cells.
Chien-Hsiu Lin 1 , Marcia Simon 2 , Vladimir Jurukovski 1 , Wilson Lee 1 , Miriam Rafailovich 1
1 Material Science, SUNY-Stony Brook, Stony Brook, New York, United States, 2 Oral Biology & Pathology, SUNY-Stony Brook, Stony Brook, New York, United States
Show AbstractThe titanium dioxide (TiO2) and zinc oxide (ZnO) nanoparticles are widely used in all types of personal care products. However, the effect of these nanoparticles on human skin is still under question. In order to understand the effects of these particles on human skin tissue, we have undertaken a comprehensive study where we compare the effects for a given concentration on different types of cells composing the skin tissue. We have found that keratinocytes are the least susceptible to damage and have the capacity to sequester the cells within the intercellular spaces. Adipocyte cells on the other hand, lose their ability to store fat even for low concentration of particles, while fibroblast cells exhibit diminished cell area, migration, and ability to contract collagen. In all cases the ZnO particles produced more harm for a given concentration than the TiO2 particles had. Coated TiO2 particles, on the other hand, had only minimal effects on all cell types. These data were obtained in the absence of UV light, since these particles are photoactive, the effects of low dose radiation on the damage will also be explored.
10:15 AM - YY4.4
Chemical Enhancer Induced Changes in the Mechanisms of Transdermal Delivery of Zinc Oxide Nanoparticles Using Two-photon Microscopy.
Tsung-Rong Kuo 1 , Chung-Long Wu 1 , Chih-Ting Hsu 2 , Wen Lo 2 , Shu-Jen Chiang 3 , Sung-Jan Lin 4 5 , Chen-Yuan Dong 2 , Chia-Chun Chen 1 3
1 Chemistry, National Taiwan Normal University, Taipei Taiwan, 2 Physics, National Taiwan University, Taipei Taiwan, 3 , Atomic and Molecular Sciences, Academia Sinica, Taipei Taiwan, 4 , Biomedical Engineering, College of Medicine and College of Engineering, National Taiwan University, Taipei Taiwan, 5 Dermatology, National Taiwan University Hospital and College of Medicine, Taipei Taiwan
Show AbstractIn this study, we succeed in combining autofluorescence of the stratum corneum and the second harmonic generation of ZnO nanoparticles to image the transdermal pathway of ZnO nanoparticles with oleic acid, ethanol and oleic acid–ethanol enhancers, using two-photon microscopy. In addition to qualitative imaging, the microtransport properties of ZnO nanoparticles were quantified to give the vehicle-to-skin partition coefficient, the second harmonic generation intensity gradient and the effective diffusion path length. The results suggested that the multilamellar lipid regions between the corneocytes were the pathways for ZnO nanoparticles delivery. With oleic acid enhancer, the transport of ZnO nanoparticles into the stratum corneum is endorsed by the phase-separated oleic acid domains, while ethanol enhancer leaches significant amount of non-covalently bound amphiphilic stratum corneum lipids to modulate the skin barrier. Among our choices of the different chemical enhancer conditions, the oleic acid–ethanol combination can be regarded as the most effective donor solution in transdermal ZnO nanoparticles into the stratum corneum.
10:30 AM - **YY4.5
Controlling the Bio-compatibility of Polymeric Nanoparticle Delivery Vehicles.
Joseph Sly 1
1 Advanced Organic Materials, IBM Almaden Research Center, San Jose, California, United States
Show AbstractStar-polymers, uni-molecular globular soft mater nanoparticles defined by a high local density of polymeric arms emanating from a central core unit, are an increasingly attractive target for biomaterials research. This talk will discuss the development of tailorable core-shell star polymer nanoparticles for use in the delivery of a diverse range of cargos from small molecule pharmaceuticals to genetic materials to light activated therapeutics to medical diagnostics. It will highlight our recent efforts to control the biocompatibility of these nanoparticles in five key areas: the development of "non-toxic" synthetic methods (scalable organic catalysis), control of complex chemical composition (bio-degradability, bio- passivation, bio-interaction), control of molecular architecture (particle shape, size, cargo space), control of intermolecular interaction (cargo loading, cell penetration, cell targeting) and control of cargo activation (carrier degradation, photon absorption, charge shifting).
11:30 AM - YY4.6
Neurotoxicity Assessment of Multifunctional Magnetic Nanospheres: A Potential Therapeutic Agent for Axonal Regeneration?
Somesree GhoshMitra 2 , Tong Cai 3 , Zhibing Hu 3 , Nathaniel Mills 2 , DiAnna Hynds 2 , Santaneel Ghosh 1
2 Biology, Texas Woman's University, Denton, Texas, United States, 3 Physics, University of North Texas, Denton, Texas, United States, 1 Physics and Engineering Physics, Southeast Missouri State University, Cape Girardeau, Missouri, United States
Show AbstractTreatment potential for many biomedical conditions is limited by the lack of therapeutics that can be precisely targeted and controlled. For instance, functional recovery following neurotraumatic injury could be facilitated by therapeutics for guided axon regeneration. Axon growth can be directed by magnetic or electrical fields alone, but a more manipulable system that provides precisely tunable therapeutic delivery may offer enhanced potential to direct axon regeneration and guidance to targets. Magnetic nanoparticles alone are highly toxic, but organic coatings can facilitate their delivery to cells. However, conventional PNIPAM based systems have huge shortcomings because the NIPAM monomer is carcinogenic and teratogenic. Moreover, biomedical applications require a tunable LCST in the range of 32-41C, which is very challenging to achieve using PNIPAM derivatives. However, we have recently designed magnetically tunable multifunctional nanostructures based on polyethylene glycol (PEG) analogue-based biopolymers with tunable LCST behavior. Since PEG is nontoxic, anti-immunogenic and approved by the FDA, idea of magnetic modulation makes it an attractive alternative that overcomes traditional difficulties in actuating conventional micro- or nanostructures by chemical, mechanical or thermal excitations. We are unaware of any study that assesses modulation of cellular function by temperature-sensitive magnetic nanospheres whose size and temperature can be precisely regulated in an oscillating magnetic field to a very localized area. In this work, we report the remarkable biocompatibility of the recently developed, novel nanocarriers at the cellular and molecular level on a neuronal model. For the nanospheres to be useful in biomedical applications, it must be relatively non-toxic and non-bioreactive, thereby allowing precise derivatization to manipulate diverse biological functions. Live/Dead assay indicated that the toxicity was far less than reported for PNIPAM or DMSA based magnetic nanoparticles. Assessment of phase-contrast images indicated that exposure to non-toxic levels (up to 6 mM Fe) of magnetic nanospheres did not inhibit the elaboration of neurites and the formation of intracellular contacts, an indication that the formation of synaptic contacts is not affected. Texas Red phalloidin labeling of filamentous actin and fluorescent tagged antibody labeling for βIII tubulin showed no apparent differences in actin filament or microtubule structure in nanosphere treated cells compared to cells not exposed to nanospheres. It is also observed that the nanospheres were internalized efficiently by the PC12 cells and nuclear morphology was unaffected. These data indicate to us that the nanospheres have the qualities that hold great promise for manipulating axon regeneration and intracellular hyperthermia. We are currently assessing the magnetic field-induced responses of several neuronal models to the bio-conjugated nanospheres.
11:45 AM - YY4.7
In vivo Biotransformation of Iron Oxide Nanoparticles can be Monitored by Magnetic Measurements.
Michael Levy 1 , Nathalie Luciani 1 , Nidhi Vats 1 , Martin Devaud 1 , Christine Longin 2 , Vanessa Devaux 3 , Sylvie Manin 3 , Eric Lancelot 4 , Sophie Lotersztajn 3 , Alain Luciani 3 , Claire Wilhelm 1 , Florence Gazeau 1
1 , Laboratoire Matière et Systèmes Complexes, Paris France, 2 , Centre de microscopie electronique, Plateforme MIMA2, Jouy en Josas France, 3 , Inserm U841, Hôpital Henri Mondor, Créteil France, 4 , Guerbet Recherche, Roissy France
Show AbstractMagnetic nanoparticles are among the most promising materials for nanomedicine owing to their properties as imaging tracers for Magnetic Resonance Imaging (MRI), as heat mediators for therapeutic hyperthermia or as controllable vectors for drug targeting. Clinically approved iron-oxide nanoparticles (known as USPIO) are considered as biocompatible since no short- or long-term toxicity was reported after their injection. Among non-organic nanoparticles, iron-based nanoparticles benefit from a peculiar status since iron is a naturally-present element in the body with a finely-regulated metabolism. Degradation products of iron oxide nanocrystals are then supposed to be assimilated by the organism. The biodistribution of USPIO is mainly governed by their size and surface coating, with a rapid uptake by cells of the reticulo-endothelial system (RES). In vitro, most cell types can internalize magnetic nanoparticles, confining them into intracellular low-pH organelles (lysosomes) where a long-term degradation can occur. However despite their wide use for in vitro/in vivo cell labeling, very few is known about the long-term fate of magnetic nanoparticles.Here we propose a new approach to follow the becoming of nanoparticles in cells or organs, by monitoring their magnetic properties. Magnetic characterization by SQUID measurements and Ferromagnetic Resonance (FMR) can provide quantitative data on the concentration and intrinsic properties of nanoparticles (size, magnetic anisotropy…). These techniques were adapted to quantify the nanoparticles content and to follow the evolution of their magnetic properties during biodegradation.To shed light on the biotransformation process, two model systems were used. On one hand, macrophages were labelled in vitro using maghemite nanoparticles with different coating and followed up to 8 days after labeling. On the other hand, we studied organs (liver, spleen and kidney) and inflammation tissues in a model of obese mice up to 44 days after IV injection of nanoparticles. For comparison, a model mimicking acidic degradation of nanoparticles in presence of iron chelator (citrate) was also studied.Results show that FMR and squid measurements are accurate techniques to quantify magnetic nanoparticles in biological samples. The study revealed that cell internalisation and confinement of nanoparticles into intracellular compartments have a drastic impact on their magnetic properties, in particular for their Néel relaxation dynamics.Magnetic behaviour of nanoparticles is thus peculiar to intracellular environment, reflecting particles organisation inside the cells consistently with TEM observations. Intracellular distribution of nanoparticles varied with the organ, with the route of cell internalisation and with the surface coating of nanoparticles.Time evolution of magnetic properties shows a very slow diminution of global magnetization, while the size distribution of nanoparticles seems to be not affected.
12:00 PM - **YY4.8
On the Effect of Size on the Surface Acidity of Metal Oxide Nanoparticles.
Lionel Vayssieres 1
1 , National Institute for Materials Science, Tsukuba Japan
Show AbstractSize effect in general and quantum size effects particularly on the physical properties and electronic structure of metals and semiconductors are well established in the literature. However, the effect of size on the chemical properties of materials and, in particular, on the surface and interfacial chemistry of hydrated metal oxides has scarcely been reported. Yet, such an effect is of great relevance for a better fundamental understanding of structure-properties relationships as well as for important environmental and industrial applications such as heterogeneous catalysis, chemical, and environmental adsorption phenomena, as well as for water purification and remediation of toxic substances and maybe of even greater importance when considering the toxicity of nanoparticles. This work investigates in details the effect of ultrafine nanoparticle size (i.e. quantum dots) on the water-oxide interfacial chemistry of iron oxide. The results demonstrate that the size of the nanoparticles has a direct effect on the surface acidity of metal oxides with the surface changing from acidic, to neutral, to basic when the size changes from 12, to 7.5, to 3.5 nm, respectively. Such result must be taken into account when establishing toxicity protocols as the interactions of nanoparticles with cells and tissues depend directly on the surface charge of the nanoparticles.
YY5: Oxide Nanoparticles II
Session Chairs
Tuesday PM, December 01, 2009
Room 308 (Hynes)
2:30 PM - **YY5.1
Relating Surface Chemistry to Acute Cytotoxicity: Metal Oxide Nanocrystals.
Vicki Colvin 1
1 Chemistry, Rice University, Houston, Texas, United States
Show AbstractNanotechnology-enabled systems offer much promise for solving difficult environmental problems ranging from water purification to waste remediation. These solutions must not only be cost-effective and sustainable, but they must also be safe for people and the environment. Our emerging understanding of the interface between nanomaterials and biological systems gives us the critical ability to approach the latter issue early in the development of nanotechnology. This talk will present how the chemical and physical properties of engineered nanomaterials impact their biological effects in model systems. Three case studies, drawn from example of relevant nanoparticle metal oxides, illustrate the vast diversity of nanomaterial features and biological response. The composition of a nanomaterial is the primary factor in describing acute biological effects, and soluble metal oxide nanoparticles such as ZnO can be toxic through their release of cytotoxic soluble metal species. For insoluble oxide nanoparticles, CeO2 and TiO2, both charge and surface coating can be of equal importance. Interestingly, the size of the inorganic material itself – such an important feature for applications development – in these three examples is secondary in defining the materials’ acute biological effect. In all cases, the biological and environmental compartments experienced by nanomaterials lead to substantial modification of their hydrodynamic size and charge. The bio-modified material that results is the central element to understand and characterize in order to detect the underlying correlations between the inorganic nanomaterial phase, composition and size with biological outcomes. These correlations form the basis for guidelines that permit researchers creating new nanoparticles to focus their energy on materials that are ‘safe by design’.
3:00 PM - YY5.2
Cytotoxicity of Vanadium Oxide Nanotubes and Their Bulk Counterparts.
Megan Roppolo 1 , Natalya Chernova 1 , Shailesh Upreti 1 , M. Stanley Whittingham 1 , Laura Rhoads 2 , William Silkworth 2
1 Department of Chemistry and Materials Science, State University of New York at Binghamton, Binghamton, New York, United States, 2 Department of Biology, State University of New York at Potsdam, Potsdam, New York, United States
Show AbstractThe varied crystal chemistry of vanadium oxides, with oxidation states of 3+, 4+, and 5+, lends them to many uses in the fields of catalysis and electrochemistry and allows for many interesting morphologies to be formed. The desirable properties of these compounds are enhanced when they are synthesized on the nano scale, due to an increase in surface area and number of reactive sites. Though nano-sized vanadium oxides may be beneficial in commercial products, little is known about their biological effects. In this work, cultured Caco-2 cells are exposed to two types of amine-templated vanadium oxides: vanadium oxide nanotubes with dodecylamine templates and ethylene diamine-intercalated (enH2)V7O16. Vanadium oxide nanotubes are made up of scrolled layers of vanadium oxide with a diameter of approximately 100 nm and lengths up to a micron. Contrarily, the morphology of (enH2)V7O16 is flat, plate-like crystals that form agglomerates up to 60 μm in size. Both the vanadium oxide nanotubes and (enH2)V7O16 have the same V7O16 wall structure with a mixed V4+/V5+ oxidation state, though magnetic studies indicate that the non-scrolled (enH2)V7O16 has a larger fraction of V4+ ions. Vanadium pentoxide, which is used as a starting material for both of these compounds, is also tested for comparison. Viability of the cell cultures is assessed with the Neutral Red assay. Though neither vanadium pentoxide nor the (enH2)V7O16 cause a reduction in viability after 24 hours, cells exposed to vanadium oxide nanotubes demonstrate a significant loss in viability after only four hours. It is believed that the morphology and nano size of the vanadium oxide nanotubes play a large role in their toxicity, perhaps disrupting cell adhesion leading to apoptosis, or by piercing the plasma membrane directly to cause necrosis. The cytotoxicity of the vanadium oxide nanotubes raises questions about the safety, handling and eventual disposal of such materials in commercial products. This work is supported by the National Science Foundation through grant DMR-0705657.
3:15 PM - YY5.3
The Effects of TiO2 Nanoparticles on Dental Pulp Stem Cell Differentiation.
Chungchueh Chang 1 , Chien-Hsiu Lin 1 , Vladimir Jurukovski 1 , Marcia Simon 2 , Miriam Rafailovich 1
1 Materials Science and Engineering, SUNY at Stony Brook, Stony Brook, New York, United States, 2 Oral biology and Pathology, SUNY at Stony Brook, Stony Brook, New York, United States
Show AbstractWe have shown that Dental Pulp Stem Cells (DPSCs) can be induced to differentiate into biomineralizing bone, cells simply by altering the mechanics of the substrates on which they are cultured. TiO2 nanoparticles have previously been shown to adversely affect dermal fibroblast function. Nanoparticles are also frequently used in dental care products such as whiteners and toothpaste. We, therefore, investigated their effects on DPSC function. DPSCs were cultured on different thicknesses of spun-cast polybutadiene (PB) thin films in standard media with TiO2 nanoparticles treatments. After 21 days incubation, Lasar Scanning Confocal Microscopy (LSCM) with mercury lamp was used to characterize the cell morphology. The Scanning Electron Microscopy (SEM) and Energy Dispersive X-ray analysis (EDX analysis) was used to analyze the elemental components of crystals. We found that cells cultured in non-induction media, were most vulnerable to damage by the nanoparticles and ceased to biomineralize after 21 days of incubation. On the other hand, cells cultured in the induction media (dexamethasone) were not affected. Hence these particles have the potential of reversing the effects of mechanical differentiation.All research was supported in part by the NSF-MRSEC program.
3:30 PM - YY5.4
Ceria Nanoparticles Affect Cellular Redox Processes.
Lina Ghibelli 2 , Ivana Francersca Celardo 2 , Milena De Nicola 2 , Corrado Mandoli 1 , Enrico Traversa 1
2 Dept. Biology, Univ. Roma Tor Vergata, Roma Italy, 1 , MANA - National Institute for Materials Science, Tsukuba, Ibaraki, Japan
Show AbstractDue to its unique redox properties, ceria is widely used for catalysis, fuel cells, gas sensors, etc. Ce (III) and Ce(IV) oxidation states can be simultaneously present in ceria. For this reason, ceria nanoparticles are considered promising radical scavenging agents in biological tissues. Ceria imparts protection against cellular damage caused by various radicals in different tissues, being considered for biomedical applications, which recommend thorough toxicity analysis. We are exploring effects of nanoceria on human cells, both to assess potential alterations on cell parameters such as viability and cell functioning, and to explore how its antioxidant properties actually work in biological tissues. To this aim, we incubated U937 human monocytic tumor cells with increasing amount of suspension of nanoceria, prepared using a soft chemical route, with particle size in the 5-10 nm range. We found that nanoceria alters the U937 cell proliferation rate, increasing growth rate at 72 h of treatment, and in parallel induces a small but significant effect on viability, inducing apoptosis at 24-48 h of treatment, which disappears after further 24 h incubation, suggesting an adaptation phenomenon. The possibility that these effects are due to nanoceria redox ability is now under study, considering that both cell proliferation and apoptosis are strictly controlled by the cell endogenous redox metabolism.
3:45 PM - YY5.5
Effects of Nanoparticle Surface Charge on Membrane Potential.
Sijie Lin 1 2 , George Huang 3 , Mercy Lard 1 4 , Pu Chun Ke 1
1 Physics and Astronomy, Clemson University, Clemson , South Carolina, United States, 2 School of Materials Science and Engineering, Clemson University, Clemson, South Carolina, United States, 3 Department of Biological Sciences, Clemson University, Clemson, South Carolina, United States, 4 Department of Physics, Lund University, Lund Sweden
Show AbstractColloidal nanoparticles have been widely used in nanomedicine as drug delivery systems and imaging agents because of their ability of penetrating through cell membranes. Nevertheless, the biocompatibility and cytotoxicity of different surface charged nanoparticles has not yet been fully investigated and understood. Cell membrane potential, the electrostatic potential across cell membrane, is crucial for numerous membrane-mediated biological phenomena such as conductance of ion channels, activation of voltage-mediated membrane proteins and trafficking across cell membranes. In this study, we used a membrane potential kit FLIPR to monitor the membrane potential change due to the introduction of positively and negatively charged nanoparticles. Although both positive and negative nanoparticles induced plasma membrane depolarization, the underlining mechanisms significantly differ. Adsorption and further endocytosis of positively charged nanoparticles inside cells neutralized the weak negative charge of inner cell membrane, resulted in membrane depolarization. For negatively charged ones, weak adsorption and little endocytosis provided an opposite electrostatic potential compared to the resting membrane potential, which resulted in membrane depolarization. Confocal fluorescence microscopy was also conducted to support these findings.
YY6: Screening and Evaluation of Nanomaterials
Session Chairs
Tuesday PM, December 01, 2009
Room 308 (Hynes)
4:30 PM - **YY6.1
Good Practice for the Assessment and Safe Handling of Nanomaterials.
Steve Hankin 1
1 Institute of Occupational Medicine, SAFENANO, Edinburgh, Scotland United Kingdom
Show AbstractNanotechnology has the potential to greatly improve our lives through medical, environmental and consumer products. Properties at the nanoscale are being exploited in new products, but they could also influence how the particles interact with humans and the environment. There is increasing consensus that for nanotechnology to reach its maximum potential, we must work to understand the hazards and exposure routes in order to minimise the risks. Good practice, founded on the principles of risk assessment and industrial hygiene, are applicable to a wide range of nanomaterials and nanostructured materials including nanoparticles, nanofibres, nanopowders, nanotubes, as well as aggregates and agglomerates of these materials. There is still considerable uncertainty about many aspects of effective risk assessment of nanomaterials, including the hazardous potential of many types of nanoparticles and the levels below which individuals might be exposed, with minimal likelihood of adverse health effects. It is prudent therefore to understand how to develop an appropriate strategy for the risk assessment, handling and disposing of nanomaterials, in the light of known and unknown hazards and exposures. The presentation will describe principles of good practice, techniques, and highlight the challenges in assessing and managing nanotechnology risk.
5:00 PM - YY6.2
Elemental Nanotechnology-An Emerging Sustainability Problem.
Barbara Karn 1
1 ORD, EPA, Washington, District of Columbia, United States
Show AbstractNew nanomaterials are being developed which consist of less common elements from the periodic table. Since there have been no prior commercial uses of these elements, little is known about their implications and interactions with living organisms and their flows through ecosystems. Even less is known about their sustainability. At least sixty of the elements on the periodic table are available commercially at the nanoscale. These nano-scaled elements could all end up in products that allow the element to pass into systems that interact with biota. While many of these elements are common, e.g., carbon, copper, iron, gold, some are rare in the earth's crust, e.g., gallium, iridium, and still very rare in commerce.About 45 of the elements are present in living organisms, some serving vital biochemical functions. However, others are present and tolerated only in minute concentrations. This paper discusses the human health, environmental, and sustainability implications of using these uncommon elements in commercial nanomaterials. I will discuss broad implications of all uncommon elements now proposed for commerce. This includes their geographic distribution, abundance, impacts of extraction, effects on living organisms, and life cycle impacts. Indium and ruthenium will be discussed more in detail. Both are being used in nanoscale form in commercial products. For each, I will discuss current known reserves, supply and demand, the uses of the element in products, possible end of life issues, toxicity and exposure routes, and then focus on the three aspects of sustainability-environmental, societal, and economic.Environmental issues will be examined from a life cycle perspective, beginning with impacts of extraction, through processing, manufacture, product use, and end of life for nanomaterials containing the element. I will discuss what is known about interactions of these elements with living organisms and how they might flow through ecosystems.Societal aspects include the human cultures affected by various life stages in the material flow such as the mining impact on land use and environmental quality, changes in behavior caused by new products, how the products might affect communications. Scarcity of elements could lead to conflicts and further widening of gaps between north and south or developed and undeveloped nations. Innovative nanoproducts using the element could impact ways of life.Economic issues could be positive for those areas rich in the element or with manufacturing capabilities. There could be negative impacts in other areas if the element proves to be essential for necessary nanoproducts, particularly those with medical uses.While this paper will raise more questions than it answers, I hope to raise the consciousness of researchers to be aware of some not-so-obvious systems implications of using rare elements in nanomaterials and then seek to prevent or minimize any foreseeable harmful impacts.
5:15 PM - YY6.3
Screening for Potential Toxicity of Nanomaterials: Implications for Responsible Manufacturing.
Shu-Feng Hsieh 1 , Eugene Rogers 1 , Daniel Schmidt 2 , Dhimiter Bello 3
1 Clinical Laboratory and Nutritional Sciences, University of Massachusetts Lowell, Lowell, Massachusetts, United States, 2 Plastics Engineering, University of Massachusetts Lowell, Lowell, Massachusetts, United States, 3 Work Environment, University of Massachusetts Lowell, Lowell, Massachusetts, United States
Show AbstractNovel nanomaterials are being created at a fast pace but little is known about their potential toxicity to human health and the environment. Biological oxidative damage (BOD) has been recognized as a key toxicity mechanism with potential to be used as a novel global metric for nanomaterial (NM) exposure and rapid toxicity screening. A ‘Ferric Reducing Ability of Serum (FRAS) assay, recently optimized by our group, was used to quantitate the degree of BOD induced by a wide range of diverse, commercially important NMs, including carbon blacks, fullerenes, carbon nanotubes, and metal oxides. This study also investigated the relationship between several physico-chemical parameters of NMs and BOD and their relevance to exposure assessment and toxicity screening.The FRAS-measured BOD strongly correlated with specific surface area and total content of select transition metals (especially Fe, Cr, Co, Mo and Mn) of the NMs tested. These two factors combined explained the majority of the observed BOD. Additionally, the observed variation in BOD exerted by the NM’s demonstrated a high concordance with other toxicological reports using more complex in vitro and in vivo assays. This strongly indicates that the simple and robust FRAS approach provides a relevant index that is useful for high throughput screening of nanomaterial toxicity.These findings support the use of BOD as a metric for NM exposure. Future work will be 1) to continue to understand the relationships between specific physico-chemical parameters of NMs and BOD exerted and 2) to provide tools that assist manufacturers in greener product production by altering physico-chemical characteristics that reduce BOD while retaining NM functionality.
5:30 PM - YY6.4
Two and Three-Dimensional Measurement Platforms for Nanoparticle Screening.
Elisabeth Mansfield 1 , Tammy Oreskovic 1 , Kavita Jeerage 1
1 Materials Reliability Division, NIST, Boulder, Colorado, United States
Show AbstractNanoparticles exist as a diverse set of materials, encompassing various shapes, compositions and intended applications. While developing and employing nanoparticles has seen significant progress, relatively little is known about the health risks associated with exposure to these particles. The properties of nanoparticles that make them attractive for biological and environmental applications (e.g., size, reactivity, and aspect ratio) are also the attributes that could contribute to their toxic response in the body or environment. The approaches to assess nanoparticle toxicity can be dramatically different from laboratory to laboratory. In some cases, the nanoparticles used in toxicity studies are not well characterized for the physico-chemical properties that may be contributing to toxicity, while in other cases the particles have been extensively characterized (such as NIST’s gold nanoparticle Reference Material). Differences between results obtained in vivo arise, even when particles do not show toxic responses in vitro. We are developing two- and three-dimensional test methods that can be used to evaluate interactions between biological systems and nanomaterials. Three-dimensional tissue engineered constructs provide an in vitro environment that can be tuned to mimic specific tissues (e.g., central nervous system). Two dimensional quartz crystal microbalance measurements provide a means to distinguish uptake as a function of nanoparticle characteristics. Aspects of this research which will be discussed include 1) characterization of the tissue engineering platform, 2) standardization of growth and differentiation conditions for neural cells to assess the influence of the nanomaterial on development, and 3) correlation of these measurements with studies of bioavailability. Ultimately, our goal is to develop measurement tools that allow for the evaluation potential toxic responses between cells and materials.
5:45 PM - YY6.5
The Role of Transition Metal Impurities in the Production of Reactive Oxygen Species and Lipid Peroxidation by Inhaled Micro- and Nano-sized Ambient and Engineered Silica Particles.
Gayatri Premasekharan 1 , Henry Forman 2 , Valerie Leppert 1
1 School of Engineering, University of California, Merced, California, United States, 2 School of Natural Sciences, University of California, Merced, California, United States
Show AbstractThe inhalation of particulate matter induces and/or exacerbates respiratory diseases in humans. The rapid proliferation of engineered particles for various applications has added a new potential source of environmental and workplace toxic substances. Transition metal-mediated generation of reactive oxygen species (ROS) has been proposed as one of the main mechanisms for particle-induced toxicity. However, efforts to unambiguously determine the role of transition metals in nanotoxicity have been hampered by incomplete physical and chemical characterization, and a lack of understanding of toxicity mechanisms. We tested the hypothesis that reactive oxygen species produced by inhaled particles react with transition metal impurities at the particle/cell surface interface to produce lipid peroxidation products from the macrophage plasma membrane, which then further directly or indirectly mediate the production of inflammatory mediators and enhance a subsequently stimulated respiratory burst. Silica particles (2µm, 50nm) were characterized for size, size distribution, and morphology using scanning electron microscopy and transmission electron microscopy. Energy Dispersive X-ray Spectroscopy and Inductively Coupled Plasma – Optical Emission Spectroscopy were used to identify transition metal composition. Elevated respiratory burst activity was observed when the THP-1 human macrophage cell line was exposed to untreated ambient silica particles in contrast to non-inflammatory, acid washed transition metal free silica particles, even at non-cytotoxic doses. Furthermore, we also evaluated whether trace transition metals result in lipid peroxidation by quantifying the peroxidation products (8-isoprostanes) in the culture media of treated cells, and found a strong release in comparison to the acid washed silica particles. The results were correlated with oxidation of diphenyl-1-pyrenylphosphine, a fluorescent probe that reacts specifically with H2O2 and organic hydroperoxides. These results indicate that transition metal impurities may play an important role in particle-induced respiratory disease and indicate a possible mechanism for their induction of an inflammatory response in the lungs.
YY7: Poster Session: Interactions of Nanomaterials with Biological Systems
Session Chairs
Wednesday AM, December 02, 2009
Exhibit Hall D (Hynes)
9:00 PM - YY7.1
A Powder Processing Route to Polymer Nanocomposites.
Giorgiana Giancola 1 , Richard Lehman 1
1 Materials Science and Engineering, Rutgers University, Piscataway, New Jersey, United States
Show AbstractPolymer nanocomposites possess excellent mechanical properties and are broadly known for high strain-to-failure behavior. The traditional route for composites with the best properties is ultrasonic dispersion of ceramic particles, such as alumina or titania, in the monomer prior to polymerization. This is a costly process and good dispersion of the ceramic particles is not assured. Other processes center on melt blending of pairs of polymers to produce immiscible polymer composites or melt blending of ceramic particles in single or multiple polymers. High shear and elongational viscosities render this approach difficult for good blending of true nanoparticle additives. In the present work, we have chosen the new route of powder processing of polymer pairs or polymer/ceramic mixtures to achieve well-dispersed and fine-domain size polymer composites. The principal advantage of this approach, aside from its relatively low cost and scale-up ability, is the tendency of the micron size polymer powders to produce uniform domain spacing and good nanoparticle spacing since the ceramic nanoparticles tend to adhere to the polymer particle surface.The PMMA/HDPE system was chosen for study since immiscible polymer blends bases on PS/HDPE, a similar system, have achieved a high level of commercial success. PMMA has superior properties compared to polystyrene and has become increasingly available and cost effective. Compositions near the 33% PMMA and 67% HDPE composition were prepared by a dry method of agitated fluidized bed mixing, and wet method of ultrasonic dispersion in isopropanol to achieve a homogeneous powder feed. Additional compositions were prepared with between one and five volume percent aluminum oxide nanoparticles of 70 nm diameter. The powder blends were compression molded to produce films. The morphology of the composites was assessed by electron microscopy. Image analysis shows that fine domain sizes are achievable in the immiscible polymer blends and that quite good dispersion of the ceramic nanoparticles can be achieve by this processing approach. The quality of the blends, from a morphological perspective, are substantially better than can be achieved by melt processing routes and in some cases the structure approaches or equals that achieved via the synthesis route. Preliminary mechanical characterization data will be presented.
9:00 PM - YY7.10
Inhibition of Inflammatory Mediator Production by Rare Earth Oxide Nanoparticles: A Potential Anti-inflammatory Nanomedicine.
Suzanne Hirst 1 , Ajay Karakoti 2 , Ron Tyler 1 , Nammalwar Sriranganathan 1 , Sudipta Seal 2 , Christopher Reilly 1 3
1 Biomedical and Veterinary Sciences, Virginia Tech, Blacksburg, Virginia, United States, 2 Advanced Materials Processing and Characterization, University of Central Florida, Orlando, Florida, United States, 3 Physiology, Virginia College of Osteopathic Medicine, Blacksburg, Virginia, United States
Show AbstractNitric oxide (NO) production by the enzyme inducible nitric oxide synthesis (iNOS) has been implicated as a critical mediator of inflammation. Overproduction of NO by the enzyme iNOS may induce tissue injury by forming reactive oxygen species including superoxide or peroxynitrate. The valence and oxygen defect properties of cerium oxide nanoparticles suggests that it may act as an auto-regenerative free radical scavenger. Herein, we present the ability of nanoceria to scavenge reactive oxygen species (ROS) and inhibit inflammatory mediator production in J774A.1 murine macrophages. Our studies showed that nanoparticles with specific surface chemistry was internalized by cells, nontoxic, and that oxidative stress and pro-inflammatory iNOS protein expression was abated with stimulation. In vivo studies showed nanoparticles deposition in mouse tissues with no pathogenicity. Taken together, our studies suggest that these nanoparticles are well tolerated in mice and are incorporated into cellular tissues. Furthermore, we demonstrate that these rare earth nanoparticles may have the potential to reduce ROS production in states of inflammation and therefore serve as a novel therapy for chronic inflammation.
9:00 PM - YY7.11
A Novel Approach for Assessment of Lung Toxicity by Nanoparticle Inhalation.
Melinda Ostendorf 1 , Nina Joshi 1 , Melanie Tomczak 1
1 Biotechnology, UES, Inc, Dayton, Ohio, United States
Show AbstractNanoparticles present new opportunities to increase the performance of traditional products and to develop new products such as powerful drug delivery systems, electronics circuits and light-harvesting materials. The rapid proliferation of these diverse materials may present both human health and ecological problems. Many of the same properties that make them desirable for commercial and medical applications also may lead to biological activity not evident from traditional products. Inhalation is a major route of exposure commonly associated with occupational exposure to ultrafine airborne particles. Respiratory absorption of nano-sized material may occur through the mucosal lining of the trachea or bronchioles, or through the alveolus. Toxicological effects of experimental nanoparticles can be tested using an in vitro lung model comprised of a normal human bronchial epithelial cell culture grown at an air-liquid interface system. This model is more organotypic than most well established monolayer culture cell lines. The human bronchial epithelial air-liquid cell model favors the development and retention of epithelial features including bioelectrical properties, mucin secretion and ciliagenesis (Gray et al., Am. J. Respir. Cell Mol. Biol. Vol. 14. pp. 104-112, 1996). The exposed lung model can be used to assess cytotoxicity, cytokine production, and oxidative stress induced by exposure to nanoparticles.
9:00 PM - YY7.12
A Novel Platform for Bio-Detection.
Amrita Banerjee 1 , Dieter Moller 1 , Haim Grebel 1
1 ECE, New Jersey Institute of Technology, Newark, New Jersey, United States
Show AbstractMetallo-dielectric screens have been investigated from the visible to the THz spectral region for astronomy and remote sensing applications. These screens are made of periodic structure, which is at resonance with the IR wavelength of interest. A standing wave of surface charges is formed at resonance conditions, which enables transmission or, reflection of certain IR bands. Graphene is a monolayer thick crystal of carbon. It is chemically inert and exhibits very large mobility values. Recently, we succeeded in fabricating mono and a few-layered suspended graphene on top of IR screens. The result is a new spectroscopic platform, which enhances weak IR and Raman signals of molecules and specifically, bio-species which are residing on the graphene layer. The IR absorption and Raman signals of bio-species under test have exhibited strong dependence on the screen periodicity pitch as well as on its orientation.
9:00 PM - YY7.13
Characterization of Cytotoxicity of Silver Nanoparticles.
Sung Yang 1 , Yu Lee 1 , Lianqing Li 1
1 , Kyung Hee Univ, Yongin Korea (the Republic of)
Show AbstractCurrently, nanotechnology has been received much interests since their significant implications including nanoelectronics, nanophotonics, catalysts, sensors, and pollution control. Unusual physical, chemical, and biological properties of nanoscale materials can enable nanotechnology to solve the current problems including energy, medical, sensor, and environmental problems. In particular, Ag nanoparticles have attracted much attention for their potential applications in electronics, antimicrobial agent, sensor applications. However, there is a possible health and environmental effects of silver nanoparticles since Ag ion is believed to be toxic material. So, it is essential to evaluate the possible health effects of Ag nanoparticles including the hazardous properties and the dose-response relationships. We have synthesized different sizes and shapes of Ag nanoparticles and modified surface property via ligand exchange reaction. We have determined the concentration of Ag ions using Ag ion sensitive fluorescent molecules. We have characterized the physico-chemical properties including size, shape, surface area, surface chemistry of Ag nanoparticles and their relationship with releasing property of Ag ion and cytotoxicity.
9:00 PM - YY7.14
Uptake of Quantum Dots by Plants.
Annie Wang 1 , John Dixon 2 , Zoraida Aguilar 2
1 , Fayetteville High School, Fayetteville, Arkansas, United States, 2 , Ocean NanoTech, LLC, Springdale, Arkansas, United States
Show AbstractThe saying “less is more” has become increasingly true. Nanotechnology is becoming quickly incorporated into not only scientific research, but also daily life. Nanoparticles are platforms for the nanotechnology and some nanoparticle-based products that are becoming increasingly common. With this exposure comes research over its effects. Many research projects, though, have focused on the toxicity of nanoparticles in small animals and cells. Little attention has been paid to the uptake of the nanoparticles by plants. The nanoparticles, when released into the environment, will find their way into water and soil and might be absorbed by plants, beginning their climb up the food chain. This presentation’s objective is to study how plants absorb nanoparticles and how these nanoparticles are distributed within plants. The red fluorescence quantum dots less than 10 nm in diameter were chosen as the optical probe to study their uptake by Mung bean sprouts (Vigna radiata) due to the nanoparticles’ high stability, high brightness, and small nanosize. The experimental results showed that the Mung bean sprouts were able to absorb the quantum dots and the quantum dots were accumulated at the plant’s root and tip. Affected Mung bean sprouts showed a stunted growth compared to non-affected ones.
9:00 PM - YY7.16
The Biocompatibility of Sub-micron and Nano Rough Titanium Surface features in the Application of Vascular Stents.
Jing Lu 1 , Thomas Webster 1
1 , Brown University, Providence, Rhode Island, United States
Show AbstractIntroductionBio-inspired nano-materials might provide a promising replacement for current drug-eluting vascular stents, which, according to recent studies, perform suboptimally. With the help of nanotechnology, topography, roughness and surface energy of vascular stents could be modified without changing surface chemistry or bulk mechanical properties to enhance vascular endothelial cell functions and deactivate the immune system which often leads to stent restenosis. Materials and MethodsNano (feature less than 50nm in the lateral and/or vertical scales) and sub-micron (features larger than 100nm in the lateral and/or vertical scales) rough titanium, with different surface energies but the same chemistry, were created by E-beam evaporation by varying emission current and deposition rate.A co-culture system was used to investigate endothelial cell function in the presence of smooth muscle cells for up to 5 days. The endothelial cell adhesion was tested under a parallel flow chamber system to mimic the real situation in natural flood vessels. Fibrinogen adsorption was test for 4 hours. Finally, monocyte (THP-1) and macrophage (IC-21) adhesion experiments were conducted for up to 24 hours. The adherent cell density and secreted cytokines were analyzed.Results and ConclusionsEndothelial cell proliferation assays were conducted for 1, 3 and 5 days. In the two culture systems (endothelial-cell-only and co-culture-with-vascular smooth-muscle-cells), both nano and sub-micron rough surface features on titanium vascular stents increased vascular endothelial cell proliferation under both static (culture plates) and dynamic (homemade parallel flow system) conditions compared to conventional titanium (controls) and sub-micron roughness behaved better than nano roughness. Primary extracellular matrix protein adsorption results showed that compared with flat titanium surfaces, fibrinogen adsorption was not promoted by either sub-micron rough or nano rough surafaecs, which might indicate the two surface topographies might minimize platelet activation. In addition, the preliminary results of monocyte/macrophage attachment assay indicated that, sub-micron surface features in titanium could significantly inhibited the attachment of monocyte (THP-1)/macrophages (IC-21), no matter they were stimulated or not. And more importantly, the cytokine releases (TNF-α, Il-1 and Il-6) of the cells were also decreased on these surfaces. All these results showed that nano and sub-micron structured surfaces were biocompatible with vascular cells and have great potential in inhibiting in-stent restenosis.
9:00 PM - YY7.17
Self-assembled Nanotubes for Multiple Drug Delivery Applications.
Yupeng Chen 1 3 , Usha Devi Hemraz 4 , Shang Song 3 , Hicham Fenniri 4 , Thomas Webster 2 3
1 Chemistry, Brown University, Providence, Rhode Island, United States, 3 Division of Engineering, Brown University, Providence, Rhode Island, United States, 4 National Institute for Nanotechnology and Department of Chemistry, National Research Council and University of Alberta, Alberta, Alberta, Canada, 2 Orthopaedics, Brown University, Providence, Rhode Island, United States
Show AbstractRosette nanotubes (RNTs) are novel biomimetic self-assembled drug delivery devices. With the self-assembly process of RNTs, different drug combinations can be either chemically functionalized on the nanotubes (like short peptides or growth factors), or physically absorbed in the nanotubes (like hydrophobic anti-cancer drugs) for specific purposes. In addition, RNTs are able to be injected into the physiological environment as a liquid and solidify into a viscous gel at body temperatures. RNTs are about similar in size to collagen in bone and cartilage. Previous studies have shown that RNTs are biocompatible and increase the adhesion of numerous cells compared to other commonly used orthopedic implant materials (like hydrogels and Ti). Thus, it is hoped that RNTs can serve as an in situ curable, multiple drug delivery vehicle to improve bone cell (like osteoblast) adhesion and long term functions, as well as to achieve anti-cancer or anti-infection purposes. In this study, RNTs were functionalized with three short peptides from bone morphogenetic protein-7 (BMP-7), which are proved to enhance osteoblast cell proliferation and long-term functions. In addition, Dexamethasone (growth factor) and Tamoxifen (anti-cancer drugs) were absorbed by RNTs. The functionalized nanotubes were characterized by NMR, MS, elemental analysis and SEM. Drug release kinetics was also tested. Importantly, results showed that the RNTs improved cell intergration with conventional implant materials. In addition, the BMP-7 peptides or Dexamethasone released from RNTs enhanced osteoblast proliferation and long term functions, and the existing of Tamoxifen could inhibit cancer cell growth. In this manner, this in vitro study provided a self-assemble implant material which relies on nanotechnology to deliver multiple drugs to improve cell functions.
9:00 PM - YY7.2
Investigating the Interaction between Carbon Nanotubes and Lipid Monolayers: Structural and Morphological Characterization and Nanotoxicity Aspects.
Juliana Cancino 1 2 , Thatyane Nobre 1 , Sergio Machado 2 , Valtencir Zucolotto 1
1 IFSC, University of São Paulo, São Carlos Brazil, 2 IQSC, University of São Paulo, São Carlos Brazil
Show AbstractNanotoxicology refers to the study of the interaction between nanostructures and biological systems with an emphasis on elucidating the relationship of physical and chemical properties of nanostructures with induction of toxic biological responses. Recently, nanomaterials such as carbon nanotubes (CNTs) have received enormous attention in the creation of new types of analytical tools for biotechnology and life sciences. Most of these applications involve the administration or implantation of carbon nanotubes and their matrices into patients. In this study we investigate the interactions between carbon nanotubes with both biomembrane model systems and natural membranes, aiming at elucidating the action of this nanomaterial in cell membranes at the molecular level. The penetration of CNT at 2 mg/ml into dipalmitoylphosphatidylcholine (DPPC) monolayers was studied using Brewster angle microscopy (BAM) simultaneously with kinetics absorption and surface pressure measurements. The nanomaterial was inserted into the monolayer, since the molecular area shifted to higher values, compared to those values obtained for pure DPPC. BAM images took at different surface pressures gave complementary information on the interaction and structural characteristics of DPPC monolayer with CNTs, which corroborate the conclusions derived from the π-A isotherms. This findings suggest that CNTs were able to interact even at high surface pressure values, viz., 30 mN/m, under controlled ionic strength, pH and temperature. Therefore the results confirm the interaction between CNTs and cell membrane models, and indicate that the presence of the nanomaterial affects the packing of the synthetic membranes, which is important for nanotoxicity studies.
9:00 PM - YY7.3
Nanoparticle as a Photosensitizer for Bacterial Reduction via Photodynamic Therapy.
Carla Fontana 1 , Nikolaos Soukos 2 , Mansoor Amiji 3 , Niraj Patel 3 , Clovis Grecco 1 , Vanderlei Bagnato 1
1 Departamento de Física e Ciência dos Materiais, Instituto de Física de São Carlos da Universidade de São Paulo USP, São Carlos , São Paulo, Brazil, 2 Applied Molecular Photomedicine Laboratory, The Forsyth Institute, Boston, Massachusetts, United States, 3 Department of Pharmaceutical Sciences, School of Pharmacy, Bouvé College of Health Sciences, Northeastern University, Boston, Massachusetts, United States
Show AbstractBackground and Objective: Photodynamic therapy has emerged as an alternative to antimicrobial regimes and mechanical means in eliminating dental plaque species. Photodynamic therapy for human infections is based on the concept that a photosensitizing agent, known as photosensitizer, can be preferentially taken up by bacteria and subsequently activated by light of the appropriate wavelength in the presence of oxygen to generate singlet oxygen and free radicals that are cytotoxic to microorganisms. In the present study, the photodynamic effects of Methylene blue-loaded biocompatible and biodegradable poly(lactic-co-glycolic acid) (PLGA) nanoparticles with positive charge were compared with those of free methylene blue (MB), Photodythazine (PDZ) and Photogem on dental plaque pathogens in rats with experimentally induced periodontitis.Materials and Methods: Periodontitis was developed by placing a ligature in the subgingival region of the right first inferior molar, in 102 rats. Twenty-five days later, the infected dental pockets were treated topically with MB (50 μg/ml), cationic MB-loaded PLGA nanoparticles (50 μg/ml equivalent to MB), Photodythazine (PDZ) (50 μg/ml) or Photogem (30 mg/ml) for 10 minutes followed by exposure to red light at 630 or 660 nm with energy fluencies of 92 and 72 J/cm2 respectively. After PDT, dental plaque samples were obtained from the treated pockets and their microbial composition was assayed using whole genomic probes to 40 oral microorganisms in the checkerboard format.Results: Cationic MB-loaded polymeric nanoparticles showed significant reduction of bacterial viability in dental plaque. Visually, clinical parameters of rat periodontum, such as redness, gingival bleeding and inflammation, were also reduced as a result of the treatment. The nanoparticles had minimal dark toxicity.Conclusion: The data suggest that polymeric nanoparticles as carriers of MB may have an application for the photodynamic therapy of periodontitis.
9:00 PM - YY7.4
Core-Shell Nanoparticles Elaborated with Chitosan.
Alejandro Torres 1 2 , Marco Garza 1 , Virgilio Gonzalez 1 2
1 Doctorado en Ingenieria de Materiales, Universidad Autonoma de Nuevo Leon, San Nicolas de los Garza, Nuevo Leon, Mexico, 2 Nanomateriales, Centro de Innovacion, Investigacion y Desarrollo en Ingenieria de Materiales, Monterrey, Nuevo Leon, Mexico
Show AbstractIn the last year the research in synthesis and structural characterization of core-shell nanoparticles has received great attention, since they could have tunable magnetic, optical, electronic and catalytic properties. In a previous work iron oxide nanoparticles were synthesized in-situ using a biopolymer as template. In this work we prepared magnetite-silver (Fe3O4-Ag) core-shell nanoparticles by co-precipitation process using chitosan as stabilizer, resulting in a material with paramagnetic behavior. The materials were characterized by UV-Vis, high resolution electron microscopy (HRTEM) nanobeam difracción (NBD) and magnetic properties were obtained using a superconducting quantum interference device (SQUID). The result in UV-Vis spectra showed typical Plasmon resonance shoulder attributed to spinel ferrite phase, we corroborate core-shell morphology and crystalline structure of both core morphology and crystalline structure of both core and shell with HRTEM, the size of the nanoparticles are about 20 nm of diameter and they show an unexpected Diluted Magnetic Semiconductor Behavior. This nanoparticles can be used to drug and gene delivery tumour destruction via heating (hyperthermia), bacterial and fungicidal.
9:00 PM - YY7.5
Dispersion Enhancement of Silica Nanoparticle in Polymer Solution by Sonochemical Surface Modification: An Application to Enameled Wires.
Yong-Beom Kim 1 , Eun-Jin Kim 1 , Young-Soo Seo 1 , Sun-Jae Kim 1 , Jong-Sun Hwang 2
1 Dept. of Nano science and technology, MRS, Seoul Korea (the Republic of), 2 Department of Computer Applied Electric, MRS, Jangheung-kun Korea (the Republic of)
Show Abstract Partial discharge resistance and thermal properties of enameled wire could be improved by adding inorganic nanofillers in the matrix resin. However, industrial applications are still limited because an aggregation between nanofillers may happen during coating processes where solvent evaporation and polymerization occur. In this study we will present a novel scheme of surface modification on silica nanoparticles with silanes using sonochemical reaction where composition and surface density of silanes can be controlled in order to reduce particle-particle attractive interaction in sophisticated matrix environments. Functionalized nanoparticles are evenly dispersed in the matrix confirmed by SEM and energy dispersive x-ray analysis. And also surface morphology of the wire with nanoparticles looks more flat, measured by AFM. Dielectric strength and thermal resistance of the wires are improved while flexibility maintains. In addition surge resistance property will also be presented.
9:00 PM - YY7.6
Differential Gene Expression Observed in Human Keratinocytes after Exposure to Gold Nanorods and Nanospheres.
Nicole Schaeublin 1 , Laura Braydich-Stolle 1 , Connie Estep 1 , Robert MacCuspie 2 , Kyoungweon Park 2 , Richard Vaia 2 , Saber Hussain 1
1 Applied Biotechnology Branch, Human Effectiveness Directorate, Air Force Research Laboratory, Wright-Patterson AFB, Ohio, United States, 2 Nanostructured and Biological Materials Branch, Materials Directorate, Air Force Research Laboratory, Wright-Patterson AFB, Ohio, United States
Show AbstractGold nanoparticles are being used in sensing, imaging, and treatment of certain cancers and as novel gene and drug delivery agents due to their unique physical and chemical properties. Despite being easily accessible and found practically everywhere, the biocompatibility of these nanomaterials has not been thoroughly examined. Many of the unique properties that must be evaluated prior to making claims of biocompatibility are surface chemistry, contaminant concentration, particle size, surface area, shape, and surface charge. The synthesis of different shaped gold nanomaterials and their stability heavily depends on the nature of the surfactants. Cetyl trimethylammonium bromide (CTAB) is reported to be an excellent capping agent in the synthesis of gold nanorods. The present study focuses on how shape and CTAB as a surfactant modulate biological interactions. Gold nanorods capped with PEG and CTAB were compared to citrate and CTAB capped gold nanospheres and biocompatibility was assessed in the human keratinocyte (HaCaT) cell line. The cells were treated with varying concentrations (0-100 µg/ml) of the AuNMs for 24 h and then biocompatibility was tested using mitochondrial function (MTS), production of reactive oxygen species (ROS) and changes in gene expression as end points. The MTS and ROS assays demonstrated similar trends, with the nanospheres being more compatible than the rods, regardless of capping agent. Additionally, changes in gene expression were observed after Au NM exposure. The nanospheres without CTAB followed similar expression patterns to control cells, while spheres with CTAB and rods with CTAB and PEG all demonstrated a massive down-regulation of pro and anti-apoptotic genes. Since the biocompatibility assays showed cell death in the presence of the massive down-regulation of apoptotic genes, the mechanism of cell death is likely necrosis. Based on these findings, both shape as well the surfactant involved in the AuNM synthesis are important factors in mediating nano gold biocompatibility.
9:00 PM - YY7.7
DNA-coated Glod Nanoparticles as Biolabel for Fluorescence Immunoassay of Glyphosate.
Hee Uk Lee 1
1 , Korea university, Seoul Korea (the Republic of)
Show AbstractGlyphosate (N-(phosphonomethyl) glycine) is a broad-spectrum systemic herbicide used to kill weeds, especially perennials. It is typically sprayed and absorbed through the leaves, injected into the trunk, or applied to the stump of a tree, or broadcast or used in the cut-stump treatment as a forestry herbicide. The official methods of analysis for herbicide rely upon high performance liquid chromatography (HPLC) or gas chromatography (GC) with sample extraction before the analysis. Immunochemical techniques are becoming very popular for mycotoxin, pesticide and herbicide analysis with many literature reporting the use of either a commercially developed enzyme linked immunosorbant assay (ELISA).In order to enhance the sensitivity in ELISA, highly sensitive glyphosate detection method based on nanoparticles and double strand DNA (dsDNA) was introduced. In this method, the dsDNA were modified with amine group and labeled with glyphosate and gold nanoparticles (AuNPs) were modified with dsDNA. The presence of glyphosate causes the formation of the sandwich structures (glyphosate–dsDNA–AuNP probes) through the interaction between the antibodies and the glyphosate. The HRP at the surface of AuNPs catalytically oxidize the substrate and generate optical signals that reflected the quantity of the target protein. Down to 1 ng/ml of protein was detected in less than 2 h with this method. This method is as simple as ELISA and has higher sensitivity than ELISA, which can potentially be exploited in food industry. This method can be used to detect protein markers of tumors, nervous system or other diseases for early diagnostics.
9:00 PM - YY7.8
Decreased Cancerous Lung Epithelial Cell Function on Nanostructured Polymers.
Lijuan Zhang 1 , Thomas Webster 2
1 Department of Chemistry, Brown University, Providence, Rhode Island, United States, 2 Division of Engineering, Brown University, Providence, Rhode Island, United States
Show AbstractPLGA (poly-lactic-co-glycolic acid) has been widely used as a biomaterial in regenerative medicine due to its biocompatibility and biodegradability properties. Previous in vitro studies have shown that cells respond differently to nano-structured PLGA surfaces compared to nano-smooth surfaces. The purpose of this in vitro research was to prepare PLGA with nanometer surface features and determine, for the first time, whether cancerous cells respond differently to such topographies. The cancer of interest in this study was lung cancer, the current leading cause of cancer death. To create nanometer surface features on PLGA, different sizes (190nm, 300nm, 400nm, and 530nm) of polystyrene beads were placed onto glass coverslips to create polystyrene monolayers of highly ordered nanobead arrays. Then, poly(dimethylisiloxane) (PDMS) molds were prepared by casting onto these polystyrene monolayers. The resulting PDMS molds were used as templates to cast PLGA films. Finally, soluble PLGA was poured over the PDMS molds, which was then allowed to evaporate at room temperature. As a result, the surface of the resulting PLGA films replicated the initial polystyrene nanobead arrays. AFM images and height profiles provided evidence that the intended spherical surface nano-topography was formed. Lung cancer epithelial cell (A549; ATCC) adhesion results showed that such cells adhered much less to specific nanometer featured PLGA compared to nano-smooth (currently-used) PLGA. Specifically, lung cancer cells adhered less on the 190nm and 400nm PLGA surface features after 4 hours of adhesion compared to any other surface created. In this manner, PLGA with nanometer surface features could inhibit lung cancer cell function which may provide an important biomaterial for the treatment of lung cancer during a wide range of applications (from drug delivery to regenerative medicine).
9:00 PM - YY7.9
Biocompatibility of GPC Nanocomposites.
Bopha Chhay 1 , Daryush Ila 1
1 , Alabama A&M University, Normal, Alabama, United States
Show AbstractGlassy Polymeric Carbon (GPC) is a unique material widely used because of its high temperature properties, inertness and biocompatibility. In the medical field, GPC is used for making artificial heart valves and prosthetic devices.Unfortunately, such as glass, GPC is brittle. Previous results has shown that its fracture strength and other mechanical characteristics were improved by developing GPC-based nanocomposites.In this work, we have introduced nanopowders of carbon nanotubes CNT, silicon carbide (SiC) and alumina (Al2O3) in the precursor of GPC and studied the biocompatibility of the nanocomposites. A cell attachment study will be performed on the GPC composites, as well as SEM and Raman measurement to characterize the mateials.
9:00 PM - YY7: Interaction
YY7.15 Transferred to YY1.6
Show Abstract
Symposium Organizers
Thomas J. Webster Brown University
Huinan Liu University of Pittsburgh
Robert Hurt Brown University
YY8: Interactions of Nanomaterials with Biological Systems
Session Chairs
Wednesday AM, December 02, 2009
Room 308 (Hynes)
9:30 AM - YY8.1
Correlative Microscopy of Nanometre Sized Particles in Human Tissue Surrounding Hip Replacements.
Angela Goode 1 , Chithra Karunakaran 2 , Alister Hart 3 , Alexandra Porter 1 , Mary Ryan 1 , David McComb 1
1 Materials, Imperial College London, London United Kingdom, 2 , Canadian Light Source, Saskatoon, Saskatchewan, Canada, 3 Charing Cross Hospital , Imperial College London, London United Kingdom
Show AbstractCobalt-chromium metal-on-metal (MOM) hip replacements generate nanoparticulate wear debris containing species which may be associated with (a) local inflammatory response and (b) white blood cell DNA damage and experimentally induced sarcomas linked to carcinogenic hexavalent chromium. We have correlated two high resolution spectro-microscopy methods to study the distribution and chemical speciation of particles in periprosthetic tissue from patients with failed MOM hips. Scanning transmission x-ray microscopy (STXM)* delivers a spatial resolution about 25nm with 0.1eV spectral resolution in x-ray absorption spectroscopy (XAS). Scanning transmission electron microscopy (STEM) gives a spatial resolution of 0.3nm combined with an energy resolution of 0.15eV in monochromated electron energy-loss spectroscopy (EELS). These complimentary methodologies provide spatially resolved quantitative information on the oxidation state and coordination environment. Nanostructures with two distinct morphologies are observed; pseudospherical particles ~50-200nm in diameter and high aspect ratio needles that are ~50nm diameter and up to 5μm in length. The nanostructures are located within lysosomes in macrophages in the soft tissue. Surprisingly even though the alloy contains cobalt, chromium and molybdenum (60, 30, 7 at%, respectively) the majority of the particles contain zero or trace concentrations of cobalt. Spatially resolved spectroscopy studies confirm that the particles contain chromium and analysis of the O K- and Cr L2,3-near edge structure indicates that Cr(III) is present in an octahedral environment, probably in the form of Cr(PO4). In this contribution the relationship between these observations and the corrosion mechanism of the CoCrMo alloy that lead to the inflammatory response and ultimate failure of the MOM hip will be discussed. *Experiments were carried out at the soft X-ray Spectromicroscopy beamline 10ID-1 at the Canadian Light Source
9:45 AM - YY8.2
A Contribution to the Nature and Origin of Nanosize Wear Particles from CoCrMo Metal-on-Metal Hip Joints.
Robin Pourzal 1 , Ralf Theissmann 2 , Serhiy Vasnyov 3 , Birgit Gleising 1 , Sylvia Speller 3 , Alfons Fischer 1
1 Materials Science and Engineering, University Duisburg-Essen, Duisburg Germany, 2 Faculty of Engineering and CeNIDE, University Duisburg-Essen, Duisburg Germany, 3 Institute for Molecules and Materials, Radboud University Nijmegen , Nijmegen Netherlands
Show AbstractSince the introduction of CoCrMo alloy metal-on-metal hip replacements have performed well clinically. Metal-on-metal couplings produce a much lower wear rate and volume than metal-on-polyethylene. However, the large number of nm-size particles being released into the body raises increasing concerns about long term biocompatibility.To investigate these particles and their origin in metal-on-metal hip replacements it is essential at first to understand the micro-structural changes in the sub-surface region of the CoCrMo alloy.For this study the articulating surface of hip implants with different head/cup diameters were analyzed by means of transmission electron microscopy (TEM) and atomic force microscopy (AFM). The TEM was used to visualize the microstructure and determine the chemical composition in the subsurface zone of the implants. The AFM investigation was performed in order to characterize the tribo-layer upon the surface after wear. The results revealed that the superior wear performance of this CoCrMo alloy is linked to a strain induced fcc to hcp phase transformation and in-situ recrystallization under shear stress. The result is a nano-crystalline surface zone which undergoes an ongoing process of mechanical intermixing with components of the interfacial body fluid. The incorporation of organic carbon from proteins in between the nano-crystals could be visualized by electron energy loss spectroscopy and energy dispersive x-ray spectroscopy. The extent of these micro-structural alterations differs depending on the size of the implant. It appears that mechanical mixing only occurs in implants with a smaller head/cup diameter (d=28mm) as opposed to a larger (d=46mm). The AFM measurements proved the presence of an organic layer strongly adhering to the metal surface. Within the layer metal particles were found with a size range of 15-80nm. These results confirm the findings of an earlier study by e.g. Catelas et. al [1] which showed by TEM investigation the size, shape and chemical composition of wear particles generated in-vivo and in simulator tests. The nature of these particles appears similar to the nc-zone observed and characterized in our study. Thus, the nc-zone must be the origin of wear particle detachment. The reason for particle detachment has yet to be clarified. However, the occurrence of mechanical mixing is suspected to be a key factor during this process. [1] Catelas et. al, Journal of Biomedical Materials Research A, 2003, 67(1), 312-327
10:00 AM - YY8.3
Interactions of Natural Organic Matter with Engineered Nanocrystals.
Divina Navarro 1 , Sean Depner 1 , Kathleen Coughlin 1 , Diane Youker 1 , Diana Aga 1 , David Watson 1 , Sarbajit Banerjee 1
1 Chemistry, University at Buffalo, SUNY, Buffalo, New York, United States
Show AbstractThe imminent large-scale commercialization of engineered nanomaterials including semiconductor quantum dots (QDs) and metal oxide nanocrystals has raised concerns regarding their potential environmental impact. Understanding the partitioning behavior and obtaining information on the mobility and persistence of these materials in ground water is critical for evaluating potential ecological hazards, estimating human exposure, and framing informed policy. Interactions of these engineered nanomaterials with natural organic matter will undoubtedly play an important role in the transport and partitioning of these materials in ground water and soil. Our recent studies indicate that both CdSe quantum dots and hafnium/zirconium oxide nanocrystals capped by various organic ligands phase transfer from organic to aqueous solutions under the influence of humic and fulvic acids. The phase transfer process is thought to be driven by two distinctive interactions: a “surfactant” mechanism wherein the humics adopt a micellar structure to enable phase transfer and a “coordinative” mechanism involving the exchange of surface-passivating ligands on the nanocrystals for humic functional groups. The humics are able to achieve the dispersion and stabilization of nanomaterials in the aqueous phase, followed subsequently by some apparent leaching of the constituent ions. The kinetics and extent of phase transfer have been studied as a function of the capping ligand (for CdSe nanocrystals) and surface-terminating planes (Hf/ZrO2 nanocrystals). The interactions between engineered nanocrystals and humic acid and fulvic acid as model natural organic matter systems have been probed using high-resolution transmission electron microscopy, dynamic light scattering, optical absorption, Raman, and infrared spectroscopies, and inductively coupled plasma elemental analysis probes. Furthermore, these results appear to be broadly generalizable to real environmental samples acquired from local sources. This work was primarily supported by the Environmental Protection Agency under grant no. R833861.1.Navarro, D., Watson, D.F., Aga, D.S. & Banerjee, S. Natural organic matter-mediated phase transfer of quantum dots in the aquatic environment. Environ. Sci. Technol. 43, 677-682 (2009).
10:15 AM - YY8.4
Novel Anti-Cancer, Anti-Bacterial Coatings for Biomaterial Applications: Selenium Nanoclusters.
Phong Tran 1 , Erik Taylor 2 , Love Sarin 2 , Robert Hurt 2 , Thomas Webster 3
1 Physics, Brown University, Providence, Rhode Island, United States, 2 Divison of Engineering, Brown University, Providence, Rhode Island, United States, 3 Divisions of Engineering and Department of Orthopaedic Surgery, Brown University, Providence, Rhode Island, United States
Show AbstractTwo common problems with implantation after cancerous tumor resection are cancer recurrence and bacteria infection at the implant site. Tumor resection surgery sometimes can not remove all the cancerous cells, thus, cancer can return after implantation. In addition, bacteria infection is one of the leading causes of implant failure. Therefore, it is desirable to have anti-cancer and anti-bacterial molecules which both rapidly (for anti-infection purposes) and continuously (for anti-cancer purposes) are available at the implant site following implantation. Therefore, the objective of the present in vitro study was to create a multi-functional coating for anti-cancer and anti-bacterial orthopedic implant applications. Elemental selenium was chosen as the biologically active agent in this effort because of its known chemopreventive and anti-bacterial properties. Selenium nanoclusters were coated on three commonly used orthopedic materials: titanium, stainless steel and ultra high molecular weight polyethylene (UHMWPE). Three different selenium cluster densities were prepared on each type of substrate. Compared to uncoated surfaces, substrate surfaces coated with selenium nanoclusters inhibited functions of cancerous bone cells and S. aureus (a key bacteria infecting all implants). Evidence of a strong interfacial bond of selenium nanoclusters to the substrates (i.e., titanium, stainless steel and UHMWPE) and a slow release rate of selenium into the culture media indicated that the coatings will be continuously available on the implants. Thus, this study provided for the first time a coating material (selenium nanoclusters) to the biomaterials’ community to both inhibiting cancer growth and preventing bacteria infection.
11:00 AM - YY8.5
In-Vitro Biocompatibility of Polymeric Ionic Liquids.
Ross Johnson 2 , Ashley Dear 2 , Erica Langley 2 , Melody Thurman 2 , Marina Sofos 1 , Millicent Firestone 1
2 Department of Biological Sciences, Chicago State University, Chicago, Illinois, United States, 1 Materials Science, Argonne National Laboratory, Argonne, Illinois, United States
Show AbstractIn this work, we describe the design, synthesis and biocompatibility of nanostructured chemical (polymeric) hydrogels formed by the spontaneous organization of ionic liquid monomers in water. The first polymer is prepared by photopolymerization of a binary mixture of 1-decyl-3-vinylimidazolium chloride and 15 % (w/w) water. Small angle X-ray scattering (SAXS) shows the polymer adopts a well-ordered hexagonal perforated lamellar structure (HPL). The second hydrogel is a copolymer formed by the photopolymerization of 1-decyl-3-methylimidazolium acrylate, ([C10mim+][Acr-] and poly(ethylene glycol) diacrylate (PEGDA) in 9 % (w/w) water and is also determined to adopt a HPL structure. The compatibility of the poly(IL)s with cultured Chinese Hamster Ovary (CHO) cells are examined. The influence of the poly(IL)s on CHO cell morphology and viability were carried out using bright-field optical and electron microscopy at selected time points up to 72 hours. In vitro cytotoxicity, using MTT and trypan blue exclusion have also been conducted. For the duration of the studies the poly(IL)s were determined to have minimal to no effect on cell growth or viability.
11:15 AM - YY8.6
Assessment of Nanomodified Endotracheal Tubes in a Bench Top Airway Model.
Mary Machado 1 , Thomas Webster 2 , Keiko Tarquinio 3
1 Division of Engineering, Brown University, Providence , Rhode Island, United States, 2 Division of Engineering and Division of Orthopaedics, Brown University, Providence , Rhode Island, United States, 3 Division of Pediatric Critical Care Medicine, Rhode Island Hospital, Providence , Rhode Island, United States
Show AbstractVentilator associated pneumonia (VAP) is a serious and costly clinical problem. Specifically, receiving mechanical ventilation over 24 hours increases the risk of VAP and is associated with high morbidity, mortality and medical costs. This complication is especially hard to diagnose in children because of non-specific clinical signs and lack of established diagnostic methods. Cost effective endotracheal tubes (ETTs) that are resistant to bacterial infection would be essential tools for the prevention of VAP. In addition to their bacterial resistance, ETT with magnetic nanoparticles could aid in the diagnosis of VAP allowing physicians to locate infections with greater accuracy. The objective of this study was twofold, first to develop strategies to decrease bacterial adhesion on currently used ETT and secondly to develop better methods to assess in vitro bacterial adhesion or biofilm formation of ETT. In preliminary tests, nanomodified polyvinyl chloride (PVC) ETTs has been shown to be effective at reducing bacterial colonization. Moreover, preliminary results demonstrated promise towards decreasing bacterial colonization using both magnetic nanoparticles and selenium coated ETT. This study also sought to evaluate the bacterial resistance of these ETTs more effectively by creating a bench top airway model, which can create a similar environment to the flow system that ETTs are exposed to in vivo. The airway model designed to test ETTs has two Plexiglas chambers representing the oropharynx and the lungs, a tube representing the trachea and finally an intricate pumping system to the oropharynx with bacteria flow and to the lung with simulated compliance and resistance. ETTs will be connected to a ventilator and passing the oropharynx into the trachea and observed under the mechanical ventilation and continuous bacterial flow system. In addition, the study examined dual gas flow conditions and their effect on bacterial growth of ETT.In no less than three separate trials in the airway chamber, each ETT will be tested for its effectiveness at the reduction of bacterial growth within the airway by sampling from both lung and oropharynx chambers during continuous operation. Special attention will be given to the long-term effects on the ETT by including a study that lasts longer than ten days. Both the bacterial proliferation in the two chambers and on the ETT itself will be carefully analyzed. This specialized testing should yield valuable information on the efficacy of nanomodified ETT in airway conditions and will provide further evidence to determine if nanomodified ETTs are a valid solution to VAP.
11:30 AM - YY8.7
Biocompatibility and Safety of a Hybrid Nanoparticulate OP-1 Delivery System Intramuscularly Administered in Rats.
Ziyad Haidar 1 2 3 , Reggie Hamdy 3 4 5 , Maryam Tabrizian 1 2 3
1 Faculty of Dentistry, McGill University, Montreal, Quebec, Canada, 2 Department of Biomedical Engineering, Faculty of Medicine, McGill University, Montreal, Quebec, Canada, 3 Center for Biorecognition and Biosensors, McGill University, Montreal, Quebec, Canada, 4 Centre for Bone and Periodontal Disease Research, McGill University, Montreal, Quebec, Canada, 5 Shriners Hospital for Children and Division of Orthopaedic Surgery, Montreal Children's Hospital, McGill University, Montreal, Quebec, Canada
Show AbstractA hybrid, nanosized, localized and release-controlled bone morphogenetic protein delivery system consisting of a liposomal core incorporated into a shell of alternating layer-by-layer self-assembled natural polyelectrolytes has been formulated. Hydrophilic, monodisperse, spherical and stable cationic nanoparticles (≤350nm) with an extended shelf-life allowing immediate protein loading prior to clinical administration resulted. In vitro cytotoxicity was previously assayed with MC3T3-E1.4 mouse preosteoblast cells and cell viability determined by colorimetry showing no adverse effects. In this study, the potential in vivo toxicity, biocompatibility and tissue presence of unloaded and loaded nanoparticles with bone morphogenetic porotein-7 (also known as osteogenic protein-1 or OP-1) were investigated. Young male normal Wistar rats (N=22) were injected intramuscularly and monitored over a total period of 10 weeks for any signs of inflammation and/or adverse reactions. Blood samples (600μL/collection) were withdrawn on days 0 (baseline: pre-injection) and post-injections on days 1, 7, 14, 28, 56 and 70. Hematological and biochemical analysis followed. Body weight changes over the treatment period were noted as well. Finally, upon animal sacrifice, major organs were harvested, weighed and examined histologically and histomorphometrically for any pathological changes. The muscular injection site was examined immunohistochemically for bone formation. Overall, all animals showed no obvious toxic health effects, immune responses and/or change in organ functions. The nanoparticles seem to localize the release and effect of the bioavailable OP-1 into the injection site. Hence, a safe and promising nanosized carrier for the administration of therapeutic growth factors is presented.
11:45 AM - YY8.8
International Journal of Nanomedicine Distinguished Scientist Award: Nanopreparations for Delivery of Undeliverable Drugs.
Vladimir Torchilin 1
1 , Northeastern University, Boston, Massachusetts, United States
Show AbstractDrugs, which are poorly soluble, have very low stability in the body, demonstrate fast elimination and/or poor accumulation in the required zone, are very difficult to convert into acceptable dosage forms and there are a lot of problems with their delivery in vivo.Thus, for example, poorly soluble substances often represent promising drug candidates, however serious problems with their delivery in the body and preparation of bioavailable dosage forms of such substances prevents them from becoming real drugs. Various formulation strategies based on the use of nanocarrier systems have been suggested to overcome poor solubility of many drugs, including anticancer ones (paclitaxel, PCT; camptothecin, CPT; and photodynamic therapy, PDT, agent, meso-tetraphenylporphine, TPP). Among such systems, polymeric micelles have drawn much attention owing to their easily controlled properties and good pharmacological characteristics. Micelles prepared from PEG-diacyllipids conjugates, such as PEG-PE, are of particular interest. Alternatively, a so-called layer-by-layer (LbL) technology (alternative coating of nanoparticles of poorly soluble drugs with layers of oppositely charged biocompatible soluble polymers) can also be applied to prepare stable nanocolloids of many poorly soluble drugs. Here, we will discuss the preparation, properties, and activity against cancer cells in vitro and in vivo of PCT-, CPT-, and TPP-loaded PEG-PE micelles and immunomicelles tumor-targeted using the anti-cancer monoclonal 2C5 antibody. Similarly, the results with the nanocolloids of poorly soluble drugs prepared using the LbL in combination with sonication will also be discussed. In some cases, the use of nanopreparations is the only way to meet an unmet medical need. Thus, to keep contrast agent in the blood during the time sufficient for an effective CT imaging, one has to prepare long-circulating nanoparticles loaded with the contrast, such as heavily iodinated micelles. In other cases, poor stability of a potential drug in the body can represent a serious problem, such as in case of siRNA, and the use of nanocarriers may represent a possible solution. Polymeric micelles containing a hydrophobized derivative of siRNA can serve as a good example. Comparative analysis of various approaches for making deliverable dosage forms of "undeliverable" substances using nanotechnology approaches will be presented.