Robert I. MacCuspie National Institute of Standards and Technology
Gregory V. Lowry Carnegie Mellon University
Stacey Harper Oregon State University
Corinne Chaneac College de France
RR1: Are My Nanomaterials Safe? Topics on NanoEHS and Risk Assessment I
Monday PM, November 29, 2010
Independence E (Sheraton)
9:30 AM - **RR1.1
International Collaboration on Nano EHS Research: The OECD's Silver Nanoparticle Effort
Jeff Morris 1 Show Abstract
1 , EPA, Washington, District of Columbia, United States
In 2008, the OECD's Working Party on Manufactured Nanomaterials (WPMN) began a collaborative effort to develop an approach for exploratory testing on silver nanoparticles. The United States and Korea have partnered with Australia, Canada, Germany, and the Nordic Council of Nations to on a silver nanoparticle testing program, the first phase of which will conclude in December 2011. This presentation highlights the approach, challenges, and preliminary findings that have emerged from this interdisciplinary international collaboration.
10:00 AM - **RR1.2
Quantitative Bionanoscience, a Rational Basis for Understanding Nanoparticles Interactions with Living Systems.
Kenneth Dawson 1 Show Abstract
1 Chemistry , University College Dublin, Belfield Ireland
The importance of understanding the interactions between nanoscale materials and living matter has now been appreciated by an extraordinarily range of stakeholders. As the potential to manipulate materials at nanometer scale grows this leads to the opportunity to stipulate and study specific interactions with cells, tissue, organs and whole organisms. Not only does this open up new directions in nanomedicine and nanodiagnostics, but it offers the chance to implement nanotechnology across all industry in a safe and responsible manner. The underlying reasons are real and durable. Less than 100nm nanoparticles can enter cells, less that 40 nm they can enter cell nucleus, and less that 35 nm they can pass the blood brain barrier. These are fundamental length scales of biological relevance that will ensure that engineered nanoscience will impinge on biology and medicine for many decades. Our core idea is that nanoparticles in a biologically relevant environment (cell media, plasma etc.) draw to themselves a number of proteins and lipids that form a sort of dynamical ‘corona’ in slow exchange with the environment. The exchange times (of the ‘hard corona’) can be so slow that many early biological responses are already defined by these associated biomolecules. It is these biomolecules that define the biological identity of the nanoparticles making it important to learn their identity, and more broadly to develop methods to assess them, including in situ. Key issues to ensure quantitative reproducibility are control of the exposure dose, which involves understanding the nature and evolution of the particle dispersion in the relevant exposure media (e.g. cell culture medium supplemented with 10% foetal calf serum) over the time course of the experiment; ensuring that the experiments are performed under identical conditions and with identical timings for each replicate; and applying a range of complementary approaches involving both imaging, molecular biology in a time-resolved manner to elucidate nanoparticle uptake, localisation and eventually functional impacts, connecting them to material properties and the nature of the protein corona in the biological milieu.
10:30 AM - **RR1.3
Optimizing in vivo Assessment of Nano/bio Interactions to Guide Safer Material Design.
Robert Tanguay 1 , Lisa Truong 1 Show Abstract
1 Environmental and Molecular Toicology and The Oregon Nanoscience and Microtechnologies Institute and the Safer Nanomaterials and Nanomanufacturing Initiative, Oregon State University, Corvalllis, Oregon, United States
The rapid rate of discovery and development in the nanotechnology field will undoubtedly increase both human and environmental exposures to engineered nanoparticles. Whether these exposures pose a significant risk remains uncertain. Despite recent collective progress there remains a gap in our understanding of the nanomaterials physiochemical properties that drive or dictate biological responses. The development and implementation of rapid relevant and efficient testing strategies to assess these emerging materials prior to large-scale exposures could help advance this exciting field. I will present a powerful approach that utilizes a dynamic in vivo zebrafish embryonic assay to rapidly define the biological responses to nanoparticle exposures. Early developmental life stages are often uniquely sensitive to environmental insults, due in part to the enormous changes in cellular differentiation, proliferation and migration required to form the required cell types, tissues and organs. Molecular signaling underlies all of these processes. Most toxic responses result from disruption of proper molecular signaling, thus, early developmental life stages are perhaps the ideal life stage to determine if nanomaterials perturb normal biological pathways. Through automation and rapid throughput approaches a systematic and iterative strategy has been deployed to help elucidate the nanomaterials properties that drive biological responses.
11:30 AM - RR1.4
What the ``Cell" Sees in Bionanoscience.
Francesca Baldelli Bombelli 1 , Dorota Walczyk 1 , Marco Monopoli 1 , Iseult Lynch 1 , Kenneth Dawson 1 Show Abstract
1 , UCD, Dublin Ireland
Nanoparticles in contact with biological fluids interact with a range of biomolecules in a quite specific manner. The biomolecules form a corona around the nanoparticles; it might be this corona of biomolecules that determine the fate of the biomolecule-nanoparticle complex as it interacts with cells rather than the “bare” nanoparticle. We have shown that for particles of the same material, differences in size and surface charge alter the composition of the corona significantly. This implies that extreme care must be taken in the development of nanomedicine and nanotherapeutics in terms of controlling the manufacturing process of nanoparticles and control of the surface properties of the final product. Moreover, the nanoparticle-protein complex changes and evolves depending on the nanomaterial composition, the plasma concentration, and the time of incubation, making understanding of the manifold processes that occur at the nano-bio interface extremely important. Here, we apply several different methodologies, in a time resolved manner, to follow the lifetime of such biomolecular ‘coronas’. For several nanomaterial types we find that blood plasma-derived coronas are sufficiently long lived that they, rather than the nanomaterial surface, are likely to be what the cell sees . Such particle-corona complexes can be physically isolated from the surrounding medium, and studied in some detail. From fundamental science to regulatory safety, current efforts to classify the biological impacts of nanomaterials (currently according to bare material type and bare surface properties) may be assisted by the methodology and understanding reported here.  Walczyk, D. et al., J. Am. Chem. Soc. 2010, 132, 5761–5768
11:45 AM - RR1.5
Gold Nanoparticles Cytotoxicity.
Tatsiana Mironava 1 , Michael Hadjiargyrou 1 , Marcia Simon 1 , Vladimir Jurukovski 1 , Miriam Rafailovich 1 Show Abstract
1 , SUNY, Stony Brook, New York, United States
Gold nanoparticles can be easily functionalized which allows the production of new drugs with chemical groups that target cancer cells, and due to the high electron density of Au, allow for enhanced imaging. However, their potential health risk(s) and interactions with cells are not fully known. Many reports brought forth the fact that such nanoparticles exhibit exotic physical properties that allow them to penetrate unusually deep into skin and other organs. Most previous studies have focused determining the general proliferation or apoptosis levels for cells exposed to AuNPs, after relatively short exposures, less than 24 hours that might not be enough to reveal cellular impairment. The skin is the primary source of contact for nanoparticles, therefore, we chose to conduct our studies using different sizes of AuNPs 13 nm and 45 nm and different types of human skin cells: keratinocytes, dermal fibroblasts and adipocytes. Our results indicates that nanoparticles induce cell damage in terms of cell proliferation, cell area, structural and extracellular matrix (ECM) protein expression and apoptosis, damage is a function of time, particle size and concentration. More specific, 13 nm AuNPs induce 45% apoptosis and up to 90% apoptosis in case of 45 nm gold. Expression of fibronectin protein is decreased in 40% and 45% after incubation with 13 nm and 45 nm AuNPs respectively. Collagen is also reduced in 35% and 42% in cells cultured in presence of 13nm and 45 nm gold. The fibronectin/collagen ratio is alerted which is normally associated with ECM hardening and aging. AuNPs found to inhibit lipid formation in adipocytes. Cell recovery once the particles are removed was also investigated, cells were found to undergo almost full recovery as a function of time.
12:00 PM - RR1.6
Correlation of Toxicity of Metallic Nanoparticles with Physiochemical Properties.
Yujie Xiong 1 Show Abstract
1 School of Engineering & Applied Science, Washington University in St. Louis, St. Louis, Missouri, United States
As nanotechnology progresses from research and development to commercialization and use, it is imperative to explore the associated risk of toxicity in well-controlled studies. Current toxicological knowledge about engineered nanoparticles is limited and traditional toxicology does not allow for a complete understanding of the effects of nanoparticle shape, size, and composition on biological systems. Nanotoxicology research is typically conducted with commercially available nanomaterials, of which the following inconsistencies have been noted: i) size, shape, composition and surface chemistry are not well controlled; ii) significant physiochemical variations exist from different batches or sources; iii) nanomaterials are not fully characterized during the manufacturing stage. To address the related environmental, health and safety (EHS) issues, we propose a systematic and reliable method of evaluating the toxicity of nanoparticles from the point of view of materials scientists. In our research, nanomaterial synthesis is tightly controlled and followed by thorough materials characterization to improve toxicity evaluation reliability. We systematically monitor cell viability, cell proliferation and reactive oxygen species after exposure to nanomaterials with variable size, shape, composition and surface group/charge properties using yeast as well as HepG2 human cells as model systems. This study will improve our fundamental understanding of how human cells respond to specific nanoparticle parameters and may provide guidance for designing safe nanomaterials for various applications.
12:15 PM - RR1.7
Pathways of Nanoparticle Endocytosis and Delivery to Lysosomes.
Anna Salvati 1 , Iseult Lynch 1 , Kenneth Dawson 1 Show Abstract
1 , Centre for BioNano Interactions, University College Dublin, Dublin Ireland
The importance of understanding the interactions between nanoscale materials and living matter is now being fully appreciated. Nanoparticles are of an appropriate size to interact with cells, and are likely to use a range of cellular machinery for internalisation and trafficking to various subcellular compartments. By understanding and controlling the rules underlying these interactions, nanoparticles could be used in nanomedicine and nanodiagnostics, while also ensuring a safe development of nanotechnologies, by answering the concerns of nanosafety.Nanoparticles composed of very different materials can enter the cells easily, and those without a targeting moiety are often seen to accumulate in lysosomes, with no clear evidence of their subsequent export or degradation. This raises concern relating to bioaccumulation in the cells, but at the same time very different outcomes for the cell can be observed, depending on the nature of the material: in some cases no alteration of cellular function can be detected, whereas in other cases some specific nanoparticles can induce cell death.In order to understand these different outcomes, controlled and reproducible exposure of cells to selected nanoparticles has been achieved and can be quantified: using a combination of fluorescence based techniques and electron microscopy, spatial and temporal localisation of nanoparticles has been resolved from early entry to their final localisation.RNA-mediated silencing has been used to understand the mechanisms of cell entry by nanoparticles, and preliminary results are presented for different nanomaterials with different properties, such as surface charge and protein corona composition, following contact with cell serum. As the tested nanoparticles are trafficked to the lysosomes, different pathways appear to be activated, including lysosomal damage and cell death. For these cases, apoptosis, autophagy and necrosis seem to be interconnected and the relation of these different pathways to the nanoparticle uptake mechanism(s) and localisation is explored.
12:30 PM - RR1.8
Towards a Better Understanding of Nanoparticle Uptake and Intracellular Processing.
Peter Sandin 1 , Verena Schueller 1 , Christoffer Aberg 1 , Francesca Baldelli Bombelli 1 , Kenneth Dawson 1 Show Abstract
1 Centre for BioNano Interactions (CBNI), School of Chemistry and Chemical Biology, University College Dublin, Dublin Ireland
In the last decade(s) the amount of literature exploring the interaction between nanomaterials and biological systems has grown exponentially. The bulk of the literature contains observations and demonstrations; explanation and understanding, however, are scarce. Detailed mechanistic insights into the processes governing the fate of nanomaterials after coming into contact with biological systems are, to a large degree, still lacking. Much of our effort at CBNI (Centre for BioNano Interactions) is directed towards obtaining a fundamental understanding of the bio-nano interactions which are imperative in successfully predicting potential health risks of new nanomaterials, engineering nanomaterials for use in e.g nanomedicine and safety issues around handling of nanoparticles. The present study was undertaken to increase our understanding of nanoparticle uptake into cells and their subsequent processing. To this end cells were exposed to pulses of nanoparticle dispersions (followed by a “chase time”) instead of the, for uptake studies, more commonly used continuous nanoparticle exposure. By changing from continuous to pulsed exposure we could extract more information on how nanoparticles are taken up by the cells. In a series of pulse & chase experiments we showed, for example, how the presence of internalized nanoparticles affects subsequent nanoparticle uptake, and how the uptake is influenced by the formation and evolution of the protein corona. Furthermore, a newly developed method using advanced 4D live cell imaging allowed us to study the time dependent spatial distribution, transient localisation and final fate of the nanoparticles after cellular internalization, all in real-time under biologically relevant conditions. The results presented here are an important step towards a deeper understanding of the mechanisms of nanoparticle uptake and processing, which in turn will underpin future nanosafety considerations, risk assessment and design of functional nanomaterials for biological use (e.g. nanomedicine).
12:45 PM - RR1.9
The Exposure Assessment of Photo-catalytic TiO2 Nanoparticles.
Sung Yang 1 , LianQing Li 1 , Miri Yu 1 Show Abstract
1 , Kyung Hee University, Yongin Korea (the Republic of)
Nanotechnology is going to change the world and the way we live, creating new scientific applications that are smaller, faster, stronger, safer and more reliable way. Nanotechnology also solves the current problems including energy, medical, environmental, and manufacturing problems. Nanomaterials have been received intense interests due to their potential applications in real-time and on-site detection of ions, small molecules, proteins, and viruses with high sensitivity and selectivity. In particular, photo-catalytic titanium dioxide(TiO2) nanoparticle have been widely used to clean and remediate the interior air quality. Since little is known about the potential risks of nanomaterials to human health and environment, it is important to understand the impact of nanomaterials on human and environment. We have characterized the physico-chemical properties and cyto-toxicity of commercially available photo-catalytic TiO2. We have characterized the density of TiO2 in interior air and dose-response relationship. We developed exposure scenario and carried out exposure assessment.
RR2: Are My Nanomaterials Safe? Topics on NanoEHS and Risk Assessment II
Monday PM, November 29, 2010
Independence E (Sheraton)
2:30 PM - **RR2.1
Reference Material and Standard Protocols for Cancer Nanomedicine.
Anil Patri 1 Show Abstract
1 Nanotechnology Characterization Laboratory, National Cancer Institute at Frederick (SAIC Frederick), Frederick, Maryland, United States
Nanomedicines are at the forefront of current research in drug delivery for cancer since they act as carriers for toxic chemotherapeutics, improve therapeutic efficacy by site-specific delivery thereby limiting dosage and toxic side effects. Many novel nanomaterial-based image contrast agents are also being developed that utilize inherent novel properties unique to nanomaterial, their altered biodistribution, enhance image contrast and aid in the diagnosis and treatment of disease. A multi-disciplinary team is required to evaluate and optimize the nanomaterial platforms for reproducible synthesis, analytical characterization, biocompatibility, safety and efficacy assessment. The main challenge for the clinical translation of nanomedicines, different from traditional small molecule drugs, is in the development of novel characterization methods to accurately assess the material properties for batch-to-batch consistency with predictable in vivo safety and efficacy profiles. There is an urgent need, but lack of availability, for reference material and protocols to assess various properties relevant to biological applications. This presentation would focus on the importance of reference material, inter-laboratory studies, standard methods and protocols for accelerated drug development for cancer nanomedicines. Lessons learned from pre-clinical assessment of different kinds of nanomaterial will be presented. AcknowledgmentsFunded by NCI Contract N01-CO-12400 and HHSN261200800001E
3:00 PM - **RR2.2
Precisely Manufactured Nanoparticles for ESH Analysis.
Steven Oldenburg 1 , Arianne Neigh 1 , Oanh Nguyen 1 , David Sebba 1 , Andrew Siekkinen 1 , Charles Holz 1 Show Abstract
1 , nanoComposix, San Diego, California, United States
Linking the physicochemical properties of nanoparticles to exposure, hazard, and risk is critical for developing an understanding of how to increase the safety of products that incorporate nanomaterials. One material of particular interest is nanosilver which is a potent antimicrobial and is currently incorporated into hundreds of commercial products. Here we describe a library of silver nanoparticles with precisely controlled physical and chemical characteristics that have been optimized for nanotoxicology studies. Experimental methodologies in which only a single nanoparticle property are varied can be used to provide insight into the effect that characteristics such as size, shape, surface, and agglomeration state have on nanoparticle toxicity. By leveraging the unique optical and electromagnetic properties of nanosilver, coupled with a monodisperse, unagglomerated, highly purified suite of spherical, rod, triangular, and nanoplate shaped particles, new insights into the in-vitro and in-vivo dynamics of nanoparticles can be obtained and correlated with toxicology data.
3:30 PM - **RR2.3
An Ecotoxicological Assessment of Nanoparticles: Case Study on Fractionated Nanosilver Suspensions.
Al Kennedy 1 , Jessica Coleman 1 , Jennifer Goss 1 , Anthony Bednar 1 , Matthew Hull 2 , Jonas Gunter 3 , Mark Chappell 1 , Jeffery Steevens 1 Show Abstract
1 , US Army Engineer Research and Development Center, Vicksburg, Mississippi, United States, 2 , NanoSafe, Inc., Blacksburg, Virginia, United States, 3 , Luna Innovations, Blacksburg, Virginia, United States
Understanding and screening the toxicological effects of nanomaterials in environmental and biological systems is critical to foster sustainable product development. Our research has applied this strategy to the byproducts of nanoparticle synthesis, nanotubes, fullerenes, nano-aluminum oxide and nano-silver (nAg). nAg has diverse anti-microbial applications for medical devices, appliances, water treatment, inks and fabrics. Potential factors impacting nAg implications include aggregation, charge, size, surface area, coating, dissolution kinetics and ligands. This investigation compared the toxicity of nAg suspensions of varying primary particle size (10 – 80 nm) and coatings to two standard aquatic test organisms (Daphnia magna, Pimephales promelas) and assessed the bioaccumulation potential of several nAg materials (30, 80, 1500 nm) associated with sediment to Lumbriculus variegatus. While expressing 48-h lethal median concentrations (LC50) of nAg suspensions as total Ag resulted in a wide range in toxicity (2 – 126 μg/L), LC50 values became more similar to LC50 values for ionic Ag (1.2 to 6.3 μg/L) when expressed as the dissolved Ag fraction (determined by differential centrifugation and field-flow-fractionation coupled with ICP-MS) of the nAg suspension (0.3 – 5.6 μg/L). While results do not necessarily imply that dissolved Ag in nAg suspensions induces all toxicity, they do suggest characterization of the dissolved fractions of nano-metals is critical. For consistency, a standard method for analytically separating the particulate and dissolved fractions needs to be developed and EHS researchers should consider reducing the dissolved fraction of metallic nanoparticles. Preliminary bioaccumulation data indicated an increasing trend in nAg uptake over time in L. variegatus. While exposure to 1500 nm particles initially resulted in higher tissue residues than 30 nm particles, residues for both particles were comparable by 28-days of exposure. Ongoing research describes the geochemical effect of dissolved organic matter (humics) to modify the inherent dispersion stability and dissolution potential of nAg.
4:30 PM - RR2.4
Assessment of Exposure to Engineered Silicon Nanoparticles in a Pilot Plant.
Tim Huelser 1 , Christof Asbach 2 , Heinz Fissan 2 , Heinz Kaminski 2 , Thomas Kuhlbusch 2 , David Pui 3 , Jing Wang 3 Show Abstract
1 Nano Energy & Nano Particle Synthesis, Institute of Energy & Environmental Technology, Duisburg, NRW, Germany, 2 Air Quality & Sustainable Nanotechnology, Institute of Energy & Environmental Technology, Duisburg, NRW, Germany, 3 Particle Technology Laboratory, University of Minnesota, Minneapolis, Minnesota, United States
General concerns exists about possible adverse health effects caused by the inhalation of engineered nanoparticles. The exposure probability can be especially high during synthesis and bagging of those materials. IUTA operates a pilot scale facility to produce various highly specific engineered nanoparticles. The facility contains a sophisticated safety concept to avoid any unwanted release of the produced particles. The effectiveness of the concept was investigated by an intensive exposure measurement campaign presented here. Our measurement plan ensured the coverage of the whole production cycle of silicon nanoparticles, including their synthesis, collection by filters, bagging, packaging and cleaning of the system. Si nanoparticles were synthesized by thermal decomposition of the precursor material silane (SiH4) in a hot wall reactor. The primary particle sizes were about 60 nm and their agglomerates several hundred nanometers. The reactor was connected through tubing to the filter housing where the generated particles were collected on filter-membranes. Subsequently, the particles were detached from the membranes by a back side pressure impulse and collected in a plastic bag underneath. The plastic bag was then sealed and removed from the system. In a separate packaging process, a worker took out samples from the bag using a spoon and filled them into laboratory glass tubes. The cleaning process involved purging the tubing system with pressurized nitrogen, opening the tubing system and manual cleaning. A suite of high time resolution instruments were used for the measurement of particle number concentrations and size distributions as well as surface area concentrations. One set of the instruments was deployed very close to the process of interest while the second set was measuring outside of the enclosure of the production facility to monitor the background. This approach helps to distinguish particles potentially released by the production processes from those stemming from the background.Our results showed that the particle concentration in the production facility were mostly comparable with that in the background. Increased particle concentrations were observed only in very few special cases, when the normally closed system was opened. For example, particle concentration peaked when the tubing was open and impacted upon during manual cleaning. An abrupt increase was also observed during the process of manually filling laboratory glass tubes with the particles. The results show that nanoparticle release from a manufacturing process can be minimized with proper procedures; however, protection for workers is still needed during special processes such as cleaning and packaging.
4:45 PM - RR2.5
Correlating Silver Nanoparticle Size and Functionalization to Generation of Reactive Oxygen Species and Ag Ion Release Rates for Disinfection Applications.
Emma Fauss 1 , James Smith 2 , Nathan Swami 1 Show Abstract
1 Electrical and Computer Engineering, The University of Virginia, Charlottesville, Virginia, United States, 2 Civil and Environmental Engineering, University of Virginia, Charlottesville, Virginia, United States
Silver nanoparticles, a common antimicrobial agent, are extensively utilized in medical applications, consumer products and water filtration. Given their widespread use and toxic effect on microorganisms, their environmental risk and impact must be established in order to create effective regulations for their safe and effective use. Prior work has suggested that both silver ions and reactive oxygen species (ROS) play a role in the disinfection mechanism of the particles. We have investigated the relationship of particle size and functionalization on the silver ion release rate and the generation of reactive oxygen species in the context of drinking water filtration. Silver nanoparticles were fabricated with diameters ranging from 10nm to 100nm and capped using sodium citrate. Particle sizes and distributions were measured using transmission electron microscopy (TEM) and dynamic light scattering (DLS) methods. A silver ion specific probe was used to measure silver ion release rates; preliminary results suggest a release rate of approximately 0.02 - 0.08 μmol / m^2*hr. Fluorescent microscopy was used to measure the generation rate of reactive oxygen species. Experimental results suggest that ROS generation was approximately 1.93 μmol / m^2*hr. ROS generation was found to be directly proportional to available surface area. While the generation of ROS exceeds the production of Ag ions, their lifetime within an aqueous environment is significantly shorter, making their toxicity difficult to directly infer. As a result, ROS is believed to be localized around the surface of the nanoparticle while Ag ions are free to diffuse into the bulk environment. Future work will focus on quantifying Ag ion release and ROS generation for various functionalized particle coatings and water samples under differing environmental conditions. Release rates of both species will be correlated to microbial disinfection rates using live/dead cell assay.
5:00 PM - RR2.6
Modulation of the Genotoxicity of Organic Pollutants by Carbon Nanotubes.
Gisela Umbuzeiro 1 , Jaqueline Honorio 1 , Daniel Morales 1 , Vitor Coluci 1 , Ronaldo Giro 1 , Diego Stefani 2 , Antonio Souza Filho 3 , Oswaldo Alves 2 Show Abstract
1 Faculdade de Tecnologia, Universidade Estadual de Campinas (UNICAMP), Limeira, São Paulo, Brazil, 2 LQES - Instituto de Química, Universidade Estadual de Campinas (UNICAMP), Campinas, São Paulo, Brazil, 3 Departamento de Física, Universidade Federal do Ceará, Fortaleza, Ceará, Brazil
Carbon nanotubes (CNTs) represent a very important class of nanomaterials due to their many potential and current applications . With the rapid growth of the number of CNT-based products, it is reasonable to expect an increase of the exposure of population and biota. Once in the environment, CNTs can interact with other compounds. One important class of compounds which has been largely investigated due to its mutagenic and carcinogenic effects is the class of polycyclic aromatic hydrocarbons (PAHs) and nitro-PAHs. These compounds are generated from fossil fuels combustion or burning of organic material . Among nitro-PAHs, 1-nitropyrene (1-NP) is the most abundant in the environment .This work aimed to study the modulation of the genotoxicity of 1-NP in the presence of CNTs. Multi-walled carbon nanotubes were produced by chemical vapour deposition process and characterized by LQES-UNICAMP. Three CNT concentrations were tested as function of different 1-NP concentrations in selected pre-incubation periods. The experiments were performed in the presence and absence of metabolic activation. The mutagenicity assay employed was the Salmonella/microsome assay (Ames test) with TA98 and YG1041 strains. The CNTs investigated in this work did not present mutagenic activity in the cited assay. The addition of CNTs reduced the mutagenicity of 1-NP and as the quantities of nanotubes increased more effective was the mutagenicity reduction. No differences were observed in relation to the different periods of pre-incubation. In order to investigate the possible interaction mechanisms between the CNTs and the 1-NP, computational modeling using first-principles density-functional theory calculations was carried out. Our results shown that 1-NP molecules can interact with the CNT surfaces through physisorption involving Pi-stacking interactions with the hydrophobic surfaces of CNTs. Covalent bonds between oxygen atom from 1-NP and carbon atoms with dangling bonds from CNT surface are also energetically favorable. These dangling bonds are due the presence of vacancies on CNTs surface produced during purification processes. The results suggest that these mechanisms can be responsible for making 1-NP molecules trapped on the CNT surfaces, reducing the 1-NP concentration able to lead to DNA mutations. R. H. Baughman, A. A. Zakhidov and W. A. de Heer, Science 297, 787 (2002). G. A. Umbuzeiro, et al., Environmental and Molecular Mutagenesis 49, 249-255 (2008). K. El-Bayoumy et al., Cancer Research 48, 4256-4260 (1988).
5:15 PM - RR2.7
Antibacterial Activity by Nanosilver Ions and Particles.
Georgios Sotiriou 1 , Sotiris Pratsinis 1 Show Abstract
1 ETH Zurich, Particle Technology Laboratory, Zurich Switzerland
The antibacterial activity of nanosilver against Gram negative Escherichia coli bacteria is investigated by immobilizing nanosilver on nanostructured silica particles and closely controlling Ag content and size. These Ag/SiO2 nanoparticles were characterized by S/TEM, EDX spectroscopy, X-ray diffraction and the exposed Ag surface area was measured by O2 chemisorption. Furthermore, the fraction of dissolved nanosilver was determined by measuring the released (leached) Ag+ ion concentration in aqueous suspensions of such Ag/SiO2 particles. The antibacterial effect of Ag+ ions was distinguished from that of nanosilver particles by monitoring the growth of E. coli populations in the presence and absence of Ag/SiO2 particles. The antibacterial activity of nanosilver was dominated by Ag+ ions when fine Ag nanoparticles (less than about 10 nm in average diameter) were employed that release high concentrations of Ag+ ions. In contrast, when relatively larger Ag nanoparticles were used, the concentration of the released Ag+ ions was lower. Then the antibacterial activity of the released Ag+ ions and nanosilver particles was comparable . G.A. Sotiriou and S.E. Pratsinis, Antibacterial activity of nanosilver ions and particles, Environmental Science & Technology, 2010, accepted.
RR3: Poster Session
Tuesday AM, November 30, 2010
Exhibition Hall D (Hynes)
9:00 PM - RR3.1
Competitive Molecular Adsorption and Formation of Functional Nanoparticle Clusters Using Complementary Physical Characterization – Application in Targeted Drug Delivery.
De-Hao Tsai 1 , Tae Joon Cho 1 , Frank DelRio 1 , Robert MacCuspie 1 , Michael Zachariah 2 3 , Vincent Hackley 1 Show Abstract
1 Ceramics Division, NIST, Gaithersburg, Maryland, United States, 2 Process Measurement Division, NIST, Gaithersburg, Maryland, United States, 3 Departments of Mechanical Engineering & Chemistry, University of Maryland, College Park, Maryland, United States
We present results based on complementary physical characterization approaches to study molecular conjugation on gold nanoparticles (Au-NPs) and the formation of functional Au-NP clusters (Au-NPCs). Thiolated polyethylene glycol (SH-PEG) functionalized Au-NPs are of particular interest in the area of cancer therapeutics due to their biocompatibility and their capacity to evade the reticuloendothelial system, thereby allowing the particles, with their therapeutic payload, to reach targeted cells. In this work, we developed a prototype physical characterization approach to investigate the adsorption kinetics of SH-PEG in the presence of another competitive but smaller molecular surface-active agent, mercaptopropionic acid (MPA). Combining dynamic light scattering (DLS) and electrospray differential mobility analysis (ES-DMA), the change in particle size due to the formation of SH-PEG coatings on Au-NPs was measured in three component systems (Au-NP + MPA + SH-PEG), and the surface coverage of SH-PEG was subsequently quantified under various conditions. A change in equilibrium binding constant for SH-PEG on Au-NPs at various concentrations of SH-PEG and MPA showed that the presence of MPA reduced the binding affinity of SH-PEG to the Au-NP surface. Kinetic studies indicated SH-PEG was desorbed from the Au-NP surface following a second-order desorption model. We also employed complementary physical characterization methods to study the formation of functional Au-NPCs. DLS was shown to have a great sensitivity to probe the formation of Au-NPCs qualitatively from the significant increase of hydrodynamic size, but its limited resolution restricts the ability to identify different forms of Au-NPCs (from dimer to large aggregates). Asymmetric field flow fractionation (AFFF) was used to improve the DLS resolution in the characterization of Au-NPCs under relevant fluid conditions and it was found that AFFF can be used not only to distinguish different cluster species (from dimers to pentamers) at the early stages of cluster formation, but it can also be used to quantify the particle clusters having different numbers of primary particles per cluster. For a quantitative comparison, ES-DMA was applied to perform characterization in the aerosol state. This work serves to demonstrate the efficacy of using a multi-technique physical measurement approach to derive important information regarding the state and dynamics of surface conjugation and cluster formation during the functionalization processes.
9:00 PM - RR3.2
The Nanoparticle-cell Dialogue: A Cell Cycle Study.
Jong-Ah Kim 1 , Anna Salvati 1 , Iseult Lynch 1 , Kenneth Dawson 1 Show Abstract
1 , Center for BioNano Interactions-Conway Insitute, University College Dublin, Dublin Ireland
Nanoparticles hold great promise as drug delivery vehicles for cancer treatment, where the lack of drug specificity for malignant cells limits the efficacy of current treatments and often leads to undesired side effects. Different parameters are being studied in relation to nanoparticle uptake in order to assess their potential role in preferential targeting of cancer cells. Some of the parameters investigated include physicochemical characteristics of nanoparticles such as size, material and surface modifications (which can influence epitope conjugation of adsorbed proteins), and also biological parameters such as the phase of the cell cycle at which cells are and cell density (which can affect cell-to-cell communication). Moreover, it has been reported that certain types of nanoparticles can have functional impacts on cells. Such effects can include alterations in cell cycle progression, which in turn can trigger cell death pathways. These phenomena could be used to systematically study the cell cycle and cell death pathways regulation, and are therefore being further investigated for their potential as novel therapeutic approaches.
9:00 PM - RR3.3
Synthesis of Magnetite Nanoparticles with Tunable Size and Narrow Size Distribution.
Jieying Jing 1 2 , Jianyu Liang 2 , William W. Yu 3 4 , Wenying Li 1 Show Abstract
1 Key Laboratory of Coal Science and Technology of Shanxi Province and Ministry of Education, Taiyuan University of Technology, Taiyuan, Shanxi, China, 2 Department of Mechanical Engineering, Worcester Polytechnic Institute, Worcester, Massachusetts, United States, 3 State Key Laboratory on Integrated Optoelectronics, College of Electronic Science and Engineering, Jilin University, Changchun China, 4 Department of Physics, Hampton University, Hampton, Virginia, United States
Magnetite (Fe3O4) nanoparticles have been widely used in environmental remediation, magnetic resonance imaging etc because of their unique and tunable magnetic properties. All these applications require that Fe3O4 nanoparticles are superparamagnetic with size smaller than 25 nm and a narrower size distribution. In this paper, Fe3O4 nanoparticles of 5 to 25 nm with a narrow size distribution were synthesized by thermal decomposition of iron carboxylate salts (iron oleate) in 1-octadecene solvent. X-ray diffraction (XRD) and transmission electron microscope (TEM) were used to determine the size of the resulting nanoparticles, dynamic light scattering (DLS) was used to characterize the size distribution of the as-synthesized nanoparticles. Results indicated that the tunable size of Fe3O4 nanoparticles can be obtained by adjusting the concentration of the reactants (the molar ratio of oleic acid to FeO(OH)) and the reaction time. Nucleation and growth processes are employed to explain the experimental observations.
9:00 PM - RR3.4
Investigating the Nanotoxicity of Silver Nanoparticles Using Cell Membrane Models.
Juliana Cancino 1 2 , Elias Berni 1 , Thatyane Nobre 1 , Sergio Machado 2 , Valtencir Zucolotto 1 Show Abstract
1 IFSC, University of São Paulo, São Carlos, São Paulo, Brazil, 2 IQSC, University of São Paulo, São Carlos Brazil
Nanomaterials have been recently explored as novel analytical tools for biotechnology and life sciences. In most cases, however, an investigation on the toxic effects of nanomaterials to living cells and tissues is required. The term nanotoxicology refers to the study of the interaction between nanomaterials and biological systems, in which emphasis is given on both the toxic effects and the elucidation of mechanism of interactions between the nanostructures and the biological material. This study was aimed at investigating the interactions occurring between silver nanoparticles AgNp (diameter of 2-3 nm) or AgNp covered with poly(vinyl alcohol) (PVA), AgNPs/PVA (diameter 8-10 nm) with membrane models composed of two phospholipids bearing different charges: 1,2-dipalmitoyl-sn-glycero-3-phosphatidylcholine (DPPC) and 1,2-dipalmitoyl-sn-glycero-3-[phospho(1-glycerol)] (DPPG). The membranes were obtained in the form of Langmuir films. The interactions between the NPs and the membranes were assessed via isotherm and kinetics measurements. The nanoparticles adsorbed and incorporated into the monolayers, as revealed by the molecular area shifted to higher values, compared with those for pure DPPG and DPPC. It was also verified that the surface pressure is highly dependent on the charge of the monolayer, confirming the interaction between AgNps and membrane models, indicating that the nanomaterial affected the packing of the synthetic cell membranes. Our findings may support in vitro measurements in which nanoparticles are allowed to interact with cells containing different surface composition.
9:00 PM - RR3.5
Expression of Virus-like Particles in Pichia Pastoris for Nanocontainer and its Application: Using CCMV, CsNIV and HcRNAV as Examples.
Hyun-Jae Shin 1 , Yuanzheng Wu 1 Show Abstract
1 Department of Chemical and Biochemical Engineering, Chosun University, Gwangju Korea (the Republic of)
Virus capsids now are considered to be perfect candidates as nanoplatform for applications in materials science and medicine. The ability of their self-assembly in vitro into virus-like particles (VLPs) makes them ideal reaction vessels for nanomaterial synthesis and entrapment. Methylotropic yeast Pichia pastoris has been used for expression of many foreign proteins recently. Here we report a heterologous expression of virus coat protein in P. pastoris which resulted in the self-assembling VLPs. Different coat protein genes derived from Cowpea chlorotic mottle virus (CCMV), Chaetoceros salsugineum nuclear inclusion virus (CsNIV) and Heterocapsa circularisquama RNA virus (HcRNAV) were synthesized according to codon preference of P. pastoris and expressed by this system. The VLPs were purified by modified polyethylene glycol (PEG) precipitation followed by cesium chloride density gradient ultracentrifugation, and then analyzed by UV spectrometry and transmission electron microscopy. The results indicated these VLPs could assemble into viral protein capsids with similar architecture and function compared to wild virus particles. This provides an alternative approach to big-scale production of VLPs by P. pastoris fermentation. Then combined particles of metal ions (Au and Cd) and PEG were successfully encapsulated into the capsids. The construction of functional nanocontainers further demonstrates potential utilization of VLPs in pharmacology or nanotechnology fields.
9:00 PM - RR3.6
Safety of Titanium Dioxide Nanoparticles on Human Skin-derived Cell.
JooKyung Lee 1 2 , Deng Xiolung 1 2 , SeongWung Kang 1 2 , Tomoji Kawai 1 2 , HeaYeon Lee 1 2 , BaeHo Park 1 2 Show Abstract
1 , Osaka university, Osaka Japan, 2 , Konkuk University, Seoul Korea (the Republic of)
Biological effects of nanomaterials with a focus on toxicity should receive great attention since commercial products as well as medical tools increasingly utilize them. Especially, a fundamental understanding of nanotoxicology is highly desirable both from the material’s stand point as well as from the biological system’s point of view. Titanium dioxide (TiO2) is a widely used material in materials sciences and engineering due to its optoelectronic properties. For example, TiO2 has been utilized as photocatalysts for photochemical hydrogen production and for self-cleaning windows. In the cosmetic industry, titanium dioxide is the main ingredient in many commercial sunscreens along side ZnO due to its property of UV absorption. However, despite its wide array of common applications, TiO2 nanotoxicology has focused on cellular level toxicity studies. In this work, the toxicity of TiO2 nanoparicles on human skin- and lung cell was investigated using 3-(4,5-dimethylthiazol-2-yl)-5-(3-carboxymethoxyphenyl)-2-(4-sulfophenyl)-2H-tetrazolium (MTS) assay- and confocal microscopy for live & dead of cells. The human skin- and lung-cell were purchase from Korean Cell Line Bank. We observed that TiO2 nanoparticles impedes the cell growth using MTS, and dead cells increase depending on the concentration of TiO2 nanoparticles using confocal microscopy. Based on the results mentioned above, we discuss the toxicity and the safety of TiO2 nanoparicles for the human cells.
9:00 PM - RR3.7
Green Chemical Synthesis of Silver Nanomaterials with Maltodextrin.
Nelson Bell 1 , Ping Lu 1 , David Tallant 1 , Timothy Lambert 1 Show Abstract
1 , Sandia National Laboratory, Albuquerque, New Mexico, United States
Silver nanomaterials have significant application resulting from their optical properties related to surface enhanced Raman spectroscopy, high electrical conductivity, and anti-microbial impact. A “green chemistry” synthetic approach for silver nanomaterials minimizes the environmental impact of silver synthesis, as well as lowers the toxicity of the reactive agents. Biopolymers have long been used for stabilization of silver nanomaterials during synthesis, and include gum Arabic, heparin, and common starch. Maltodextrin is a processed derivative of starch with lower molecular weight and an increase in the number of reactive reducing aldehyde groups, and serves as a suitable single reactant for the formation of metallic silver. Silver nanomaterials can be formed under either a thermal route at neutral pH in water or by reaction at room temperature under more alkaline conditions. Deposited silver materials are formed on substrates from near neutral pH solutions at low temperatures near 50 C. Experimental conditions based on material concentrations, pH and reaction time are investigated for development of deposited films. Deposit morphology and optical properties are characterized using SEM and UV-vis techniques. Silver nanoparticles are generated under alkaline conditions by a dissolution-reduction method from precipitated silver (II) oxide. Synthesis conditions were explored for the rapid development of stable silver nanoparticle dispersions. UV-vis absorption spectra, powder X-ray diffraction (PXRD), dynamic light scattering (DLS), and transmission electron microscopy (TEM) techniques were used to characterize the nanoparticle formation kinetics and the influence of reaction conditions. The adsorbed content of the maltodextrin was characterized using thermogravimetric analysis (TGA).Sandia is a multiprogram laboratory operated by Sandia Corporation, a Lockheed Martin Company, for the United States Department of Energy’s National Nuclear Security Administration under contract DE-AC04-94AL85000.
9:00 PM - RR3.8
Characterization of Cytotoxicity of Silica Nanoparticles.
HeeOk Park 1 , YounJung Kim 1 , Sung Yang 1 Show Abstract
1 , Kyung Hee University, Yongin Korea (the Republic of)
Currently, nanotechnology has been received much interests since their significant implications including nanoelectronics, nanophotonics, catalysts, sensors, and pollution control. Despite nanotechnology is an important and rapidly growing field of scientific and practical innovations, little is known about the potential risks of nanomaterials and nanotechnology to human health and environment. Silica (SiO2) nanoparticle is has a wide variety of applications in food, cosmetics, diagnosis, imaging and drug delivery. Recent studies have shown that SiO2 nano-particles induce cytotoxicity and genotoxicity in various cultured cells lines. In this study, we have characterized the physico-chemical properties including size, shape, surface chemistry of commercially available photo-catalytic TiO2 and MTT assay in HaCaT, BEAS2B, NIH3T3, SH-SY5Y. We have found that the cyto-toxicity of SiO2 naoparticles strongly depends on surface charge and size and cell lines. In particular HaCat and SH-SY5Y cell are more sensitive than BEAS2B, NIH3T3.
9:00 PM - RR3.9
Characterization of Cytotoxicity of Photo-catalytic TiO2 Nanoparticles.
Miri Yu 1 , Youn-Jung Kim 1 , Sung Yang 1 Show Abstract
1 , Kyung Hee University, Yongin Korea (the Republic of)
Despite nanotechnology is an important and rapidly growing field of scientific and practical innovations, little is known about the potential risks of nanomaterials and nanotechnology to human health and environment. Titanium dioxide(TiO2) nanoparticle is an important product for nanotechnology because of its high stability, anticorrosion and photocatalysis. It is frequently used in the cosmetics, pharmaceutical, paint, and paper industries. Recent studies, however, have shown that TiO2 nano-particles(nano-TiO2) induce cytotoxicity and genotoxicity in various lines of cultured cells as well as tumorigenesis in animal models. Since the nanoparticles may have different physic-chemical properties including optical, magnetic, and structural properties, however, they also may possess differential toxicity properties compared with bulk TiO2. In this study, we have characterized the physico-chemical properties including size, shape, surface chemistry of commercially available photo-catalytic TiO2 and MTT assay in HaCaT and BEAS-2B Cells. We have found that the cyto-toxicity of photo-catalytic TiO2 naoparticles strongly depends on physic-chemical properties including size, shape, surface charge, surface coating of TiO2 nanoparticles.
Robert I. MacCuspie National Institute of Standards and Technology
Gregory V. Lowry Carnegie Mellon University
Stacey Harper Oregon State University
Corinne Chaneac College de France
RR4: Characterization of Nanoparticles in Complex Media and``Relevant" Conditions
Tuesday AM, November 30, 2010
Independence E (Sheraton)
9:30 AM - **RR4.1
The Role of Measurement Standards in EHS Assessment of Engineered Nanomaterials.
Debra Kaiser 1 Show Abstract
1 , NIST, Gaithersburg, Maryland, United States
The promise of nanotechnologies and the ensuring economic and societal benefits may never be fully realized due to unknown risks of engineered nanomaterials (ENMs)—materials that are purposefully produced—and ENM-enabled products throughout all stages of their life cycles. ENMs pose risks to the environment (E) and the health (H) and safety (S) of workers, consumers, and the public. The solution to this EHS problem is to establish essential linkages between physico-chemical properties of ENMs such as size and shape, hazard effects such as toxicity, and exposure effects such as release of ENMs from products. Standards—reference materials, protocols, and documentary standards—enable accurate, precise, and reproducible property measurements required to establish these linkages. NIST is leading the U.S. effort in the development and dissemination of ENM standards. A case study using the NIST gold nanoparticle reference materials will be presented to illustrate the synergistic development of reference materials, protocols, and documentary standards for use in EHS studies of ENMs.
10:00 AM - **RR4.2
Characterization of Nanoparticles for Safety Testing of Manufactured Nanomaterials.
Asa Jamting 1 , Victoria Coleman 1 , Heather Catchpoole 1 , John Miles 1 , Jan Herrmann 1 Show Abstract
1 Nanometrology Section, National Measurement Institute Australia, Lindfield, New South Wales, Australia
Studying the impact that nanoparticles may have on the environment, health and workplace safety is becoming increasingly important. One of the challenges is how to accurately measure their physical and chemical properties such as particle size, surface area, number concentration, state of agglomeration/aggregation, and zeta potential. Furthermore, it is essential to establish which of these properties are relevant when assessing the potential risks associated with the use of nanomaterials.A number of methods are available to measure the properties of these particle systems. For size characterization, for example, the range of established techniques includes electron microscopy, such as scanning and transmission electron microscopy, dynamic light scattering, and differential centrifugal sedimentation, and novel complementary methods such as particle tracking analysis and microchannel resonator particle analysis. The interpretation of the measurement results is often based on simplified models such as that of a monodisperse suspension of spherical particles. In addition, care has to be taken when comparing results from different techniques since they are based on different measurands. For particles in complex matrices, the characterization becomes considerable more challenging. This talk illustrates how comparison of results from different measurement techniques can provide a more accurate and representative description of the physico-chemical properties of nanoparticles and how these measurements can inform the safety testing of manufactured nanomaterials.
10:30 AM - **RR4.3
Predicting Environmental Exposures of to Engineered Nanoparticles.
Mark Wiesner 1 3 , Gregory Lowry 2 3 Show Abstract
1 Civil & Env. Eng., Duke University, Durham, North Carolina, United States, 3 , Center for Environmental Implications of Nanotechnology (CEINT), Durham, North Carolina, United States, 2 Civil & Env. Eng., Carnegie Mellon University, Pittsburgh, Pennsylvania, United States
Assessing the impacts of engineered nanoparticles (ENPs) on human health and the environment requires the fundamental scientific understanding needed to predict and measure the location and concentration of ENPs in environmental media as well as understanding the toxicological impacts of those materials. The overall aim of fate and transport research for ENPs is to determine the expected concentration of ENPs in particular environmental media, and the expected chemical composition and morphology of the ENPs. We hypothesize that the chemical nature of the surface of ENPs as well as their bulk parameters (e.g. density) will in part determine their distribution in the environment, i.e. partitioning between environmental compartments as well as their persistence in the environment. The ENP surface properties determine attachment of ENPs to surfaces, an important process affecting homo and heteroaggregation, deposition onto porous media surfaces and organisms, reactivity, ultimately affecting the distribution of ENPs in the environment and their effects. Chemical and biological transformations of ENPs or their macromolecular coatings also affect the distribution of ENPs in the environment and their persistence. This includes adsorption of naturally occurring organic matter, dissolution, biodegradation of coatings, and sulfidation. Examples of how a systematic understanding of attachment of ENPs to various environmental surfaces can be used to predict partitioning of ENPs in the environment will be presented. The critical role of engineered macromolecular coatings as well as adsorbed natural organic matter on attachment to surfaces will be emphasized.
11:30 AM - RR4.4
Gold Nanoparticles: Dispersability in Biological Media, Cell-biological Effects on Human Mesenchymal Stem Cells, and Dissolution in Aqueous Media.
Dirk Mahl 1 , Christina Greulich 2 , Wolfgang Meyer-Zaika 1 , Manfred Koeller 2 , Matthias Epple 1 Show Abstract
1 Inorganic Chemistry, University of Duisburg-Essen, Essen Germany, 2 Bergmannsheil University Hospital / Surgical Research, Ruhr-University Bochum, Bochum Germany
Gold nanoparticles are frequently applied in biomedicine and have a high potential as optically tuneable carriers for cancer diagnosis and cancer therapy. It is therefore of general interest to investigate the distribution, stability and toxicity of gold nanoparticles in biological systems because this is the state where they are present when the biological action occurs.Spherical gold nanoparticles with a diameter between 11 and 13 nm were prepared according to Turkevich and stabilised with poly(N-vinylpyrrolidone) (PVP) or tris(sodium-m-sulfonatophenyl)phosphine (TPPTS) [1,2]. They were characterised by dynamic light scattering (DLS), electron microscopy (SEM, HRTEM), analytical disc centrifugation, and nanoparticle tracking analysis (NPTA). They were subjected to different cell culture media, e.g. pure RPMI, RPMI containing up to 10% of fetal calf serum (FCS), and RPMI containing up to 10% of bovine serum albumin (BSA), and the rate of agglomeration was studied by dynamic light scattering. In pure RPMI, a strong agglomeration was observed whereas in the RPMI-FCS and RPMI-BSA mixtures, the particles remained well dispersed above 1 wt% protein concentration. PVP-stabilised gold nanoparticles had no significant influence on the viability and chemotaxis of human mesenchymal stem cells (hMSC), but they induced the activation of hMSC as indicated by the release of IL-6 and IL-8. To investigate whether if the release of IL-6 and IL-8 was induced by particles or ions, the dissolution of gold nanoparticles in aqueous media was investigated by different techniques. The nanoparticles showed some degree of dissolution over extended periods of storage. J. Turkevich, P.C. Stevenson, J. Hilliery, Disc. Faraday Soc., 11 (1951), 55. G. Schmid, A. Lehnert, Angew. Chem. Int. Ed., 28 (1989), 780.AcknowledgementsWe thank Prof. A. V. Hirner (University of Duisburg-Essen) for help with the analysis of the gold samples by inductively coupled plasma mass spectrometry.
11:45 AM - RR4.5
Dispersion of Nanoparticles in Media of Biological Interest.
Nathalie Herlin Boime 1 , Axelle Casanova 1 , Marie Carriere 2 Show Abstract
1 IRAMIS/Service des Photons, Atomes et Molecules/ Laboratoire Francis Perrin, CEA, Gif/Yvette cedex France, 2 IRAMIS/ Laboratoire de Structure et Dynamique par Resonance Magnetique, CEA, Gif/Yvette cedex France
Nanoparticles (NP) are introduced in a growing number of commercial products, including food and beverage, daily use hygiene products such as toothpaste, or orally-administered drugs. To study the possible toxicity of these nanoparticles, a model system is the in vitro response of eukaryotic cells to the presence of NP. However, to understand the observed effects, it is clear that good physical and chemical characterization of NP, and in particular of their dispersion are needed. Indeed, the expected effects should be different if the study is dealing with agglomerates or isolated nanoparticles. For fundamental understanding, it appears important to work with nanoparticles as well dispersed as possible while being in relevant biological condition, i.e. cellular culture cellIn this context, we have studied the dispersion of a very common industrial titania NP (Degussa P25 produced in ton quantities). When dispersed in water, the suspensions of NP appear stable for weeks.. When transferred in the cell culture medium (DMEM) or if directly dispersed in DMEM, strong evolution of size is seen as well as sedimentation. To address this problem, we have compared different ways, coming from materials science, of dispersing NP in water with the idea to break in a preliminary step some of the necks between nanoparticles. The effect of dry ball milling, liquid ball milling, size of the balls and Ultrasonic dispersion will be compared. The best results were obtained from high power ultrasonic dispersion. To avoid direct aggregation, when going to DMEM, a "surfactant" relevant with biological studies (Foetal Bovine Serum,...) was added in the suspension in order to coat the nanoparticles prior to transfer in DMEM (or other cell media). The result obtained with various surfactants and cell media will be presented. It must be noted that our best results were obtained in the FBS + DMEM medium. Moreover, a procedure compatible with sterilization was developed.
12:00 PM - RR4.6
The Correlation Between Toxicity and the Release of Silver Ions from Silver Nanoparticles.
Joerg Diendorf 1 , Stefanie Kittler 1 , Christina Greulich 2 , Manfred Koeller 2 , Matthias Epple 1 Show Abstract
1 Inorganic Chemistry, University of Duisburg-Essen, Essen, NRW, Germany, 2 Surgical Research, University Hospital Bergmannsheil, Bochum, NRW, Germany
Silver and particularly silver nanoparticles are widely used due to their well known antibacterial effect. In medicine they are applied for wound dressings, surgical instruments, and bone substitute biomaterials, e.g. silver-containing calcium phosphate cements. Silver nanoparticles are also applied in many articles of daily use to prevent bacterial contamination, e.g. in refrigerators or textiles [1,2]. Probably not the macroscopic silver or the silver nanoparticles themselves are the biologically active agent, but silver ions, that are released. In addition, in the case of nanoparticles, living cells can take up whole particles and the constituting ions will be released inside the cell . For these reasons we examined the release of silver ions from silver nanoparticles and the relative toxicity towards cells.The dissolution of citrate-stabilized and poly(vinylpyrrolidone)-stabilized silver nanoparticles in water was studied by dialysis for up to 125 days at 5, 25, and 37 °C. The particles slowly release ions on a time scale of several days to weeks. However, in all cases a limiting value of the released silver was observed, i.e. the particles did not completely dissolve. In some cases, the nanoparticles released up to 90 % of their weight during the observation period. The rate and the degree of dissolution depend on the functionalization as well as on the storage temperature. The release of silver led to a considerably increased toxicity of silver nanoparticles which had been stored in dispersion for several weeks towards human mesenchymal stem cells due to the increased concentration of silver ions. Consequently, "aged" silver nanoparticles are much more toxic to cells than freshly prepared silver nanoparticles.Panacek, A.; Kvitek, L.; Prucek, R.; Kolar, M.; Vecerova, R.; Pizurova, N.; Sharma, V. K.; Nevecna, T.; Zboril, R., Silver colloid nanoparticles: Synthesis, characterization, and their antibacterial activity. J. Phys. Chem. B 2006, 110, 16248-16253.Jain, P. K.; Huang, X.; El-Sayed, I. H.; El-Sayed, M. A., Noble metals on the nanoscale: optical and photothermal properties and some applications in imaging, sensing, biology, and medicine. Acc. Chem. Res. 2008, 41, 1578-1586.Mahmood, M.; Casciano, D. A.; Mocan, T.; et al., Cytotoxicity and biological effects of functional nanomaterials delivered to various cell lines. J. Appl. Toxicol. 2010, 30, 74-83.
12:15 PM - RR4.7
Equilibrium-Based Dissolution Studies of Colloidal Nanocrystals.
Jacqueline Siy 1 , Michael Bartl 1 Show Abstract
1 Department of Chemistry, University of Utah, Salt Lake City, Utah, United States
The synthesis of size and shape-controlled colloidal nanocrystals has become an intense field of research fueled by the wide array of emerging applications ranging from biological labeling to light-emitting diodes, micro-lasing and solar energy conversion. Of equal importance to studies on how nanocrystals are formed, however, is also the knowledge about the “reverse” reaction: the dissolution of nanocrystals. Dissolution strongly affects the post-synthesis stability of nanocrystals and therefore is of enormous significance for their safe and controlled long-term use in all solution-based applications. This is especially the case for use of nanocrystals as optical labels in biological imaging, sensing and delivery in which dissolution can have severe implications due to the long metabolic lifetime and high toxicity of widely used nanocrystal components such as cadmium or lead. In this paper, we present a series of experiments designed to investigate the stability of colloidal nanocrystals based on simple reaction equilibrium conditions between growth and dissolution. We systematically study the dissolution behavior of beforehand-synthesized CdSe nanocrystals as a function of their size and concentration, temperature, and the presence of ligands/surfactants and other co-reactants. From these studies we can deduct important stability parameters such as dissolution rates, critical temperatures and activation barriers. We found that nanocrystals in pure or ligand-enriched solvents have a strong tendency for dissolution.
12:30 PM - RR4.8
TiO2 and ZnO Nanoparticle Agglomeration in Marine Snow.
Vincent Palumbo 1 , John Doyle 2 , Evan Ward 2 , Bryan Huey 1 Show Abstract
1 Institute of Materials Science, University of Connecticut, Storrs, Connecticut, United States, 2 Marine Sciences, University of Connecticut, Avery Point, Connecticut, United States
There is increasing concern about the impact of nanoparticles on the environment. TiO2 and ZnO particles, for example, are widely used in consumer goods, leading to the possibility of environmental exposure following consumer use, and of course through industrial accidents or waste. These nanomaterials may be incorporated among naturally occurring precipitates, ‘marine snow,’ which is an important part of the aquatic ecological system. For example, bivalves (mussels, clams, scallops, etc.) efficiently process marine snow, significantly clearing water of these particulates but with potentially harmful effects to the food chain as they are consumed by multiple species, including humans. Here, titanium dioxide and zinc oxide nanoparticles are mixed into filtered seawater to investigate agglomeration into marine snow. Bivalve tissue, and waste products, are further analyzed for nanoparticle-incorporation. Using primarily electron microscopy, as well as Energy Dispersive Spectroscopy and Focused Ion Beam methods, particle size distributions and agglomerate compositions are imaged and mapped.
12:45 PM - RR4.9
Evaluation of the Adsorption Potential of Synthesized Anatase Nanoparticles for Arsenic Removal.
Zuleyha Kocabas 1 , Yuda Yurum 1 Show Abstract
1 Material Science and Engineering, Sabanci University, Istanbul Turkey
Titanium dioxide has been extensively tested in environmental applications, especially in separation technologies. In the present study, anatase nanoparticles were synthesized by using sol-gel method for removing arsenide (As(III)) ions from water/wastewater. Several anatase nanoparticle synthesis were investigated by varying pH values in order to obtain optimum crystalline structure, morphology, and particle size of the nanoparticles calcined at 400 oC. After characterization of synthesized powders by X-ray diffraction and scanning electron microscopy (SEM), batch adsorption experiments were carried out to analyze removal capacity of the anatase nanoparticles. Residual arsenic concentrations of the solutions treated with titanium dioxide nanoparticles were measured with a Varian, Vista-Pro CCD simultaneous inductively coupled plasma ICP-OES spectrophotometer. The adsorption isotherms, kinetic and thermodynamic parameters of batch adsorption experiments were achieved. The maximum % of removal of arsenite (As+3) was found ~% 78 at pH 3, respectively when 5 g l-1 anatase nanoparticles were used at the As0 1 ppm. Anatase nanoparticles had higher adsorption capacity which was ~92% at pH 6 for 1 ppm arsenate (As+5) concentration. Experimental results of the sorption experiments, which take into consideration the effects of equilibrium concentration on adsorption capacity, were analyzed with two popular adsorption models, Langmuir and Freundlich models. From the comparison of R2 values, the adsorption isotherm for arsenite was fitted satisfactorily well to Langmuir equation with a correlation coefficient to be greater than 0.993. However, the adsorption isotherm of arsenate was fitted well to Freundlich equation with a correlation coefficient to be greater than 0.991. This study proposes the potential adsorbent material for water which is contaminated with arsenic species.
RR5: Greener Nanoparticle Synthesis and Applications
Tuesday PM, November 30, 2010
Independence E (Sheraton)
2:30 PM - **RR5.1
Strategies, Materials, Analytical Tools and Design Rules for Greener Nanotechnologies.
James Hutchison 1 2 Show Abstract
1 Chemistry, University of Oregon, Eugene, Oregon, United States, 2 , Oregon Nanoscience and Microtechnologies Institute, Corvallis, Oregon, United States
Nanotechnology offers new materials and applications that promise numerous benefits to society and the environment, yet there is growing concern about the potential health and environmental impacts of production and use of nanoscale products. Because nanotechnology is still in the “discovery” phase, the design and production of materials have yet to be optimized. For example, although hundreds of studies of nanomaterial hazards have been reported, there is no consensus about the impacts of these materials or design rules that guide the future development of the materials. Additionally, the synthetic methods used to produce nanomaterials are often inefficient or require the use of hazardous reactants. Green chemistry is an approach to the design of materials, processes and applications that has the potential to reduce hazards at each stage of the life cycle. In this presentation, I will describe how green chemistry applied to nanoscience - greener nanoscience - offers an approach to developing safer, more efficient nanosyntheses and to developing and implementing the design rules for safer nanomaterials. To advance beneficial applications of nanomaterials and minimize harm, we need to develop an understanding of how nanomaterials interact with and in the environment and their biological impacts and develop new methods of production that address the limitations of discovery scale approaches. Examples will be provided that illustrate a research approach to determining the design rules for effective and safe nanomaterials. Specifically, the use of specially designed reference nanoparticles and new analytical techniques provide insight into nanoscale structure and reactivity related to their biological impacts. The results of these types of studies can guide design of new materials for which product safety is a design metric.
3:00 PM - **RR5.2
Specific Surface Properties of Nanoparticles: An Overview.
Jean Pierre Jolivet 1 2 , Corinne Chanéac 1 2 , Sophie Cassaignon 1 2 , Olivier Durupthy 1 2 , David Portehault 1 2 Show Abstract
1 Chimie de la Matière Condensée, Universite Pierre et Marie Curie, Paris France, 2 , Collège de France, Paris France
Nanoparticles exhibit specific properties dues to mainly two reasons : a very small volume giving particles with a mean size similar to those of characteristic lengths of physics (mean free path of electron, wavelength of light, size of magnetic domains. . .), and a huge specific area. It directly influences many properties, such as the physico-chemistry of particles, particularly the interparticular forces enabling dispersion in various media, and the chemical reactivity involved in adsorption phenomena. They may have very diverse consequences, for instance in interfacial catalysis, in the transport of pollutants in ground waters or in soils, and in biological effects leading to toxicity. Surface physico-chemistry may also be implicated in the design itself of nanoparticles when it is interesting to control the shape or size to optimize their properties. All these phenomena involve acid-base and/or redox mechanisms. The talk will present an overview of these various mechanisms implicated at the interface oxide-solution with technologically interesting materials such as oxides of iron, aluminium, titanium and manganese. Comparison with other materials (metals, chalcogenides) will also shortly be discussed.
3:30 PM - **RR5.3
Mechanistic Study of Silver Nanoparticles Impregnated in Porous Ceramic Media for Developing-world Household Water Treatment.
James Smith 1 Show Abstract
1 Civil and Environmental Engineering, University of Virginia, Charlottesville, Virginia, United States
Silver nanoparticles (Ag-NPs) with mean particle diameters ranging from 10-100 nm have been studied to determine their ability to deactivate two surrogates for waterborne pathogenic microorganisms (a non-pathogenic strain of E. coli and the MS2 coliphage). Newly synthesized zero-valent Ag-NPs release ionic silver and reactive oxygen species into oxygen-saturated water, and the rate of release is approximately proportional to nanoparticle concentration and inversely proportional to nanoparticle size. Disinfection kinetics follow similar trends. Disinfection rates for E. coli are significantly greater than rates for the MS2 coliphage.Ag-NPs were impregnated into porous ceramic cylinders and these “filters” were tested for the removal of E. coli and MS2 from water at different ionic strengths. Without impregnated silver, the ceramic filters were highly effective in removing E. coli (removal percentages consistently greater than 97%) and moderately effective in removing MS2 (50-70% removal). The addition of silver nanoparticles to the ceramic porous media improves E. coli removal but has negligible effects on MS2 removal. E. coli and MS2 removal rates increase with solution ionic strength.Ceramic water filters impregnated with Ag-NPs can be produced in developing-world communities using primarily local labor and materials. Ongoing studies in Guatemala and S. Africa suggest that these ceramic filters are a sustainable, point-of-use water treatment technology that improves household water quality and human health.
4:30 PM - RR5.4
Photochemical Installation of Polyfunctional Surfaces on Nanomaterials for Biomedical Theranostics and Environmental Remediation.
Ryan Rutledge 1 , Jonathan Pittman 1 , Cynthia Warner 1 , Wilaiwan Chouyyok 1 , Marvin Warner 1 , R. Shane Addleman 1 Show Abstract
1 , Pacific Northwest National Laboratory, Richland, Washington, United States
The remediation of environmental contaminants, such as heavy metals and radioactive species, has attracted considerable interest due to the growing concern over the effects of these materials on both human health and the environment. Functionalized nanomaterial-based sorbents (e.g., mesoporous silica or superparamagnetic nanoparticles) have proven remarkably effective at capturing these toxic species, thus allowing for their detection and/or removal from solution. To date, a majority of the work with these materials has focused on the functionalization of one type of surface chemistry (e.g., thiols, phosphonic acids, hydroxypyridinones, etc.) capable of targeting one type of analyte (e.g., heavy metals, actinides, etc.). We have expanded on this work by synthesizing a polyfunctional sorbent capable of targeting several types of analytes via the installation of multiple ligand functionalities on the substrate surface. UV-induced thiol-ene “Click” chemistry was utilized to deposit alkene-modified ligands onto thiol-coated surfaces. The result is a green chemistry approach that is applicable to a number of substrates and may be tailored for the sequestration of a variety of potential analytes. As a proof-of-concept, diphosphonic acid ligand (Diphos) has been installed on the surface of thiol-coated sorbent substrates via UV-induced thiol-ene coupling. Directed deposition of the Diphos ligand has proven problematic in the past because of its large bulky headgroup and substrate-reactive functionalities. Thiol-ene coupling provides reaction conditions that are extremely fast and efficient, thus offering a means to circumvent these issues. The resulting polyfunctional materials have been characterized and proven effective at binding and removing both heavy metals (via thiol interaction) and lanthanides or actinides (via diphosphonic acid interaction) from solution with high affinities. The success of these materials at simultaneously capturing two distinctly different species of analyte suggests their utility in a variety of applications ranging from biomedical diagnostics and therapeutics to environmental contaminant detection and remediation.
4:45 PM - RR5.5
Influence of Polymer Degree of Polymerization on Attachment of Nanoparticle-Macromolecule Complexes to Environmental Surfaces.
Stacey Louie 1 , Gregory Lowry 1 Show Abstract
1 Civil and Environmental Engineering, Carnegie Mellon University, Pittsburgh, Pennsylvania, United States
As commercial production and application of nanoparticles expands, a fundamental understanding of their fate and transport in the environment is necessary to predict their distribution and potential exposure pathways. Nanoparticle transport behavior is dominated by aggregation and deposition. Nanoparticles are often coated with adsorbed organic macromolecules, including engineered polymers and natural organic matter that adsorbs upon release to the environment. These coatings significantly affect the transport properties of the nanoparticles. Therefore, predicting the effect of these coatings on aggregation and deposition is important.The morphology of the macromolecule/nanoparticle complex may affect its environmental deposition behavior. Morphology can vary on a large scale, from individual nanoparticles coated with a layer of macromolecule (macromolecule-decorated nanoparticle) to more extensive structures of several nanoparticles bridged by macromolecule (nanoparticle-decorated macromolecule). The goals of this study are to create and characterize a set of model macromolecule/nanoparticle complexes of different morphologies, and to relate their morphology to deposition onto environmental surfaces. Titanium dioxide nanoparticles with polyacrylic acid coatings of different degrees of polymerization are used to prepare the end-member morphologies. The size and structure of the coated nanoparticles are characterized by several methods, including dynamic light scattering, atomic force microscopy, and transmission electron microscopy. From these techniques, the two morphologies can be distinguished. Column elution and quartz crystal microbalance experiments are then performed to evaluate nanoparticle deposition. The effect of these different morphologies on deposition and transport will be discussed.
5:00 PM - RR5.6
A Novel Technology for Green(er) Manufacturing of CNTs via Recycling of Waste Plastics.
Chuanwei Zhuo 1 , Brendan Hall 1 , Yiannis Levendis 1 , Henning Richter 2 Show Abstract
1 Mechanical and Industrial Engineering, Northeastern University, Boston, Massachusetts, United States, 2 Materials Synthesis Research, Nano-C, Inc., Westwood, Massachusetts, United States
Costly and often highly-flammable chemicals, such as hydrogen and carbon-containing gases, are largely used as fuels in current CNT synthesis technologies. To mitigate related economic and safety concerns, we have developed a versatile CNT synthesis sequence, where low-cost and safe-to-handle-and-store waste solid polymers (plastics) are used for in-situ generation of hydrogen and carbon-bearing gases. Introduction of different waste plastics, such as polyethylene, polypropylene and polystyrene, into a multi-stage pyrolysis/combustion/synthesis reactor provides suitable feedstocks for CNT formation. This process is largely exothermic and scalable. It uses low-cost stainless steel screens to serve both as substrates as well as catalysts for CNT synthesis. This technique enables a solution for both waste plastic utilization and sustainable CNT production.
5:15 PM - RR5.7
Magnetic Recycling of Metallic Nanoparticle Catalysts.
Kevin Major 1 , Sherine Obare 2 Show Abstract
1 Department of Chemistry, University of North Carolina at Charlotte, Charlotte, North Carolina, United States, 2 Department of Chemistry, Western Michigan University, Kalamazoo, Michigan, United States
Developing practical methods for recovering homogeneous catalysts is essential for advances in industry as well as in fundamental science. Colloidal palladium (Pd) and platinum (Pt) nanoparticles are highly effective catalysts for various organic transformations. Most methods developed for synthesis of Pd and Pt nanoparticles for catalysis require that the particles are immobilized onto a substrate to heterogenize the particles. For such applications, the methods for nanoparticle fabrication often lead to polydisperse particles that often leach from the substrate on which they are immobilized. We have developed an alternative approach for catalyst recovery that involves linking Pd and Pt nanoparticles to magnetic nanoparticles. A straightforward one-step wet chemical synthetic approach was established that produced uniform and size controllable Pd and Pt nanoparticles in 90% yield. The nanoparticles were characterized by electron microscopy, x-ray diffraction and electrochemistry, before and after being linked to magnetic nanoparticle surfaces. We studied the catalytic activity of the nanoparticles toward the hydrogenation of carbon-carbon bonds. The nanoparticles exhibited excellent selectivity and were magnetically recovered and reused. The synthesis, characterization and catalytic applications of the nanoparticles will be described.
5:30 PM - RR5.8
Accelerated Photocatalytic and Post-Illumination ``Memory'' Catalytic Disinfections of Microorganisms from Photoelectron Transfer Between Nanoparticles and Visible Light Photocatalyst.
Qi Li 1 , Jian Shang 1 2 Show Abstract
1 Materials Center for Water Purification, Institute of Metal Research, Chinese Academy of Sciences, Shenyang, Liaoning Province, China, 2 Materials Science and Engineering, University of Illinois at Urbana-Champaign, Urbana, Illinois, United States
Water pathogens pose great threats to the global human health. Disinfection processes must be adopted in water treatment to effectively control pathogens in water supply. Current water disinfection processes rely heavily on chemical disinfectants. However, the production of toxic disinfection by-products (DBPs) in these processes now raises serious concerns. Photocatalytic disinfection of waterborne pathogens could avoid or minimize the formation of toxic DBPs. Recently, anion-doped TiO2 have been explored for visible-light-induced photocatalysis so that a greater portion of the solar spectrum may be utilized, which eliminates the need of expensive and possibly hazard UV light source and reduce the operation cost. However, anion doping intrinsically brings the serious problem of massive charge carrier recombination, largely limiting the photoactivity of anion-doped TiO2. Another inherent problem is that they lose their photocatalytic capability in the dark environment. Therefore, it would be most desirable to design a visible-light photocatalyst system which can provide enhanced photocatalytic efficiency by minimizing charge carrier recombination. It would be even better if the improved photocatalyst can store some of its photocatalytic activity in "memory" so that once the photoexcitation is turned off, the catalyst could still remain active for an extended period of time. Here we developed a novel visible light photocatalyst system consisting of palladium oxide (PdO) nanoparticles well dispersed on nitrogen-doped TiO2 (TiON) matrix. Clear evidences of charge flow to/from PdO nanoparticles on the visible light photocatalytic TiON matrix were obtained. The photoelectron flow to PdO nanoparticles enhanced photocatalytic disinfection efficiency under visible light illumination by the separation of electron and hole pair, while the discharging of PdO nanoparticles following the turn-off of the illumination created the unique "memory" catalytic effect on bacterial disinfection in dark. The introduction of transition metal ion modification as demonstrated with palladium in this study could be easily adapted to other transition metal ions, and the charging/discharging on PdO nanoparticles may occur in other transition metal ion-modified anion-doped TiO2 material systems. Thus, our work here could provide the basis for design of new generations of photocatalysts for a broad range of environmental applications.