Suwan Jayasinghe, University College London
Mallika Kamarajugadda, Medtronic, Inc.
Roger Narayan, University of North Carolina at Chapel Hill and North Carolina State University
Antoni Tomsia, Lawrence Berkeley National Laboratory
Symposium Support Applied Physics Reviews|AIP Publishing
M2: Advanced Polymers and Ceramics for Biomedical Applications
Monday PM, November 30, 2015
Sheraton, 2nd Floor, Liberty B/C
2:30 AM - *M2.01
Morphological Studies of Polymer Films and Formulations for Oral Drug Delivery Applications
Vipul Dave 1 Gerard McNally 1
1Johnson amp; Johnson Consumer Inc. Ft Washington United StatesShow Abstract
Different types of polymers and processes are utilized to prepare pharmaceutical formulations to achieve the desired drug delivery attributes from solid oral dosage forms. In this study, selected pharmaceutical grade polymers and additives were utilized to prepare films and coated formulations using different techniques. Experiments were performed to characterize the bulk and surface properties of the materials to gain insights into the functionality of the polymers. Examples of the methods that were utilized to characterize the materials included Thermogravimetric Analyzer (TGA) combined with an Infrared Spectrometer (TG-IR), X-ray diffraction, dynamic vapor sorption (DVS), Time-of-Flight Secondary Ion Mass Spectrometry (TOF-SIMS), and Confocal Raman Spectroscopy. Special emphasis was given to study the effect of moisture and plasticizers on the physical properties of the films and formulations. Selected formulations were developed to prepare solid oral dosage forms containing different active pharmaceutical ingredients. The presentation will provide a summary of the results obtained from characterizing the films, coated formulations and drug delivery dosage forms.
3:00 AM -
3:15 AM - *M2.03
Towards Computer-Aided, Rational Design of Ceramic Biomaterials: Combining Micro-Computed Tomography, Nanoindentation, Ultrasonic, and Micromechanical Theory
Christian Hellmich 1
1TU Wien - Vienna Univ of Technology Vienna AustriaShow Abstract
Biomaterials have been characterized by an ever increasing collection of highly advanced experimental techniques, while consistent and integrative evaluation of all related test results remains a significant, largely unmet challenge. As a remedy, we here present several recent activities.
We start with a new evaluation method (Czenek et al, J Mat Res 29, 2757ff., 2014), which uses the unique linear relationship between gray values and X-ray attenuation coefficients, together with the energy-dependence of the latter, to identify (i) the average x-ray energy used in the CT device, (ii) the X-ray attenuation coefficients, and (iii), via the x-ray attenuation average rule, the intravoxel composition, i.e., the microporosity, which, amongst others, governs the voxel-specific mechanical properties, such as stiffness and strength. The method is realized for six 3D tricalcium phosphate scaffolds, seeded with pre-osteoblastic cells and differentiated for 3, 6, and 8 weeks, respectively. The corresponding voxel-specific microporosities turn out to increase during the culturing period (resulting in reduced elastic properties, as determined from micromechanical considerations), while the overall macroporosity remains constant.
As a second example, consistent combination of nanoindentation, ultrasound, and micromechanics theory is shown by example of porous baghdadite (Ca3ZrSi2O9) scaffolds (Kariem et al, Mat Sci Eng 46C, 553ff., 2015). The resulting porosity-stiffness relations further confirm a formerly detected, micromechanically explained, general relationship for a great variety of different polycrystals (Fritsch et al, J Appl Mech 80, 020905-1, 2013),which also allows for estimating the zero-porosity case, i.e. Young modulus and Poisson ratio of pure (dense) baghdadite. These estimateswere impressively confirmed by a physically and statistically independent nanoindentation campaign comprising some 1750 indents. Consequently, we can present a remarkably complete picture of porous baghdadite elasticity across a wide range of porosities, and, thanks to the micromechanical understanding, reaching out beyond classical elasticity, towards poroelastic properties, quantifying the effect of pore pressure on the material system behavior.
The new methods are expected to further foster the development of a rationally based and computer-aided design of biomaterials and tissue engineering scaffolds.
4:15 AM - *M2.04
Sensing the Swell
Aoife Morrin 1
1Dublin City Univ Dublin IrelandShow Abstract
Hydrogels are three-dimensional networks of polymer that have great ability to imbibe exceptionally large volumes of water. The water uptake and hence swelling of hydrogels can be controlled and manipulated depending on hydrogel design. As such, their swelling can be exploited in sensing and controlled release platforms, with applications varying from providing a simple inert protective sensor coating, to use as an intelligent drug delivery system capable of sensing physiological changes and auto-titrating a drug. This presentation will describe the work we are doing on responsive hydrogel materials, their design, and applicability to both sensing and controlled release. The context of the work will be discussed within the application area of epidermal sensing, e.g., monitoring skin barrier function.
In relation to the hydrogel-based sensing platform, electrochemical impedance spectroscopy is used to sensitively track the swelling responsive of pH-sensitive hydrogels. Indeed, the demonstration of this system for glucose detection at the sub-micromolar levels opens up the possibility of glucose detection in sweat. Electrically-stimulated drug release from these hydrogels that are composited with reduced graphene oxide will also be discussed. Finally, our recent work on the fabrication of super-macroporous structures of these hydrogels and the dramatic influence of this induced structure on the material&’s swelling behaviour and hence its sensing characteristics will be presented.
4:45 AM - M2.05
Oscillatory Shear Injection for Improved Surface Nanoimprint Processing of Biopolymers for Tissue Scaffold Applications
Graham L. W. Cross 1 2 Owen Brazil 1 Daniel J Kelly 1
1Trinity College Dublin Dublin Ireland2Adama Innovations Dublin IrelandShow Abstract
Nanoimprint lithography (NIL) is a rapid, low cost mechanical technique to create nanoscale to microscale patterns across large surface areas. Although originally introduced as a potential next generation lithography for the semiconductor industry, the technique has found itself applied in a variety of applications including biomaterials and devices. Its advantage over other techniques is to be able to provide fully deterministic surface patterning, including pattern gradients and multiscale features, in a wide variety of materials. In this work we report on a new development to improve nanoimprint processing to provide both topographical and chemical function to current and potential future tissue scaffolding polymers.
In small amplitude oscillatory shear forming (SAOSF) , a small amplitude cyclic shear displacement (up to 10&’s of nm) is applied to a rigid die in contact with a soft solid film leading to a plastic-ratchet forming action (Fig. 1). As with conventional nanoimprint, nano-feature fidelity and registry are achieved, however the technique also has advantages of constant low temperature processing and hence a wide choice of materials. For solid films, the underlying mechanism of SAOSF is due to a combination of uniformly plasticizing contacted areas of the film while simultaneously activating a novel pumping action involving die-geometry-induced broken circulation of elastoplastic flow. Crucially, the process is scale independent for thin film planar imprint, since only a critical shear strain is required. A minimal applied normal load largely eliminates elastic distortions thought to be responsible for residual layer non-uniformity and other replication defects common to imprint. Finite element simulations of the process with simple elastic-elastoplastic materials agree well with experimental observations.
In this work we demonstrate the successful application of SAOSF to large area surfaces and thin films of the biodegradable polymer PLGA. Imprint dies with nanoscale patterns were imprinted with high fidelity across cm scale areas at temperatures below above and below the glass transition, greatly reducing biopolymer-die adhesion and thus increasing die lifetime, as well as reducing overall imprint time due to a short thermal cycle. We demonstrate the efficacy of this technique in influencing stem cell response to surface patterns. While currently implemented in conventional hot embossing and nanoimprint setups, steps toward adapting the approach high throughput to roll-to-roll processing will be described, including a lamination strategy allowing fully 3D porous tissue scaffolds to be fabricated with complete determinism of internally patterned surfaces. The advantages that SAOSF provides may become particular great in the continuous processing environment.
 G. L. W. Cross, B. S. O'Connell, H. O. Ozer and J. B. Pethica, Nano Lett. 7, 357 (2007).
5:00 AM - M2.06
Fabrication of Polymer Coated Microparticles with Low Permeability
Li Zhao 1 Julien Gautrot 1 Gleb Sukhorukov 1
1Queen Mary University of London London United KingdomShow Abstract
Low permeability is one of the key challenges that exists in the area of drug delivery system. Due to the nature of polymers, micro drug carriers made of polymers are usually porous which leads to the failure of retaining small molecules and narrows the applications of the polymeric micro containers. Thus, our group has been trying to overcome this shortage.
In this work, low permeable Poly(methyl methacrylate) shells which are not permeable by small molecules were fabricated via surface initiated Atom Transfer Radical Polymerization (ATRP).
The kinetics of PMMA brush growth was first studied on flat substrates on which the pre-synthesized macroinitiator was deposited using Layer-by-Layer technique. The thicknesses of the PMMA films were measured with ellipsometer. The surface hydrophobicities of different substrates with and without PMMA layer were then compared by measuring the water contact angles. Increased surface hydrophobicity was witnessed from the significantly increased water contact angle on the surface with PMMA monolayer.
Further to this, low permeable PMMA shells were synthesized on the surface of CaCO3 templates from the pre-deposited macroinitiators via ATRP polymerization. Fourier Transform Infrared Spectroscopy (FTIR) and Thermogravimetric Analysis (TGA) spectrums showed that PMMA was successfully coated on the inorganic cores. Transmission Electron Microscope (TEM) was applied to observe the thicknesses of PMMA shells and they were found to be nearly in accordance with the kinetics on planar surfaces. The results of the Energy-dispersive X-ray Spectroscopy (EDS) together with those obtained from Scanning Electron Microscope (SEM) and TEM demonstrated that there were no differences in the element compositions as well as surface and inner structures of PMMA coated particles before and after ethylenediaminetetraacetic acid (EDTA) treatment. This indicates that PMMA shells are non-permeable to the dissolution agent, which has low molecular weight.
After having proven that hydrophobic polymer shells synthesized by “brush growth” technique are able to form low permeable micro containers, the same strategy was applied to fabricate the low permeable and biodegradable Poly(lactic acid) microcapsules, the properties of which are being investigated. We believe that our work could contribute to the biomedical applications.
5:15 AM - M2.08
Inkjet Printing of Materials for Drug Delivery
Roger Narayan 1
1North Carolina State University Raleigh United StatesShow Abstract
Piezoelectric inkjet printing is a materials deposition technique that relies on pressure waves from a piezoelectric actuator to precisely pattern picoliter volumes of liquids onto a surface. We have recently utilized this approach for modifying the surfaces of microneedles, which are microscale projections that may be used for transdermal delivery of many types of pharmacologic agents. Precise patterning of several pharmacologic agents was demonstrated. The mechanical and chemical properties of the inkjet-modified devices with compared against those of the unmodified devices. In addition, the functionality of the inkjet-printed drugs was validated using in vitro assays. The results suggest that piezoelectric inkjet printing is an appropriate approach for incorporating pharmacologic agents within medical devices since it is associated with rapid processing times, low cost, and facile scalability.
5:30 AM - M2.09
Mimicking Calcareous Dinoflagellate Cysts for Core-Shell Microcapsules
Archana Lovett 1 Richard Saballos 1 Mark Bewernitz 1 2 Laurie Gower 1
1University of Florida Gainesville United States2Blue Planet- ltd Los Gatos United StatesShow Abstract
Dinoflagellates are protists, mostly found as marine plankton. Some species produce a calcareous shell around their exterior as a cyst for protection during the dormant, zygotic stage of their life. Using this core-shell architecture as an inspiration, we have developed a methodology for encapsulating “soft” liquid droplets within a “hard” mineral shell. The polymer-induced liquid-precursor (PILP) mineralization process was used to deposit a calcium carbonate (CaCO3) mineral shell on the surface of surfactant-stabilized fluidic particles comprised of either oil-in-water emulsion droplets or liposomes. Size and morphological analyses were performed by various microscopic techniques, where it was observed that the PILP droplets preferentially adsorb to anionic surfactants/lipids that stabilize the suspension, and due to their liquid-like character, coalesce to form a smooth and continuous mineral coating. The processing conditions for forming these CaCO3-coated microcapsules are benign, so they can encapsulate virtually any active agent of interest. For example, hydrophobic compounds can be dissolved in oil-in-water emulsions, while hydrophilic and/or hydrophobic compounds can be dissolved within liposomes, which can then be coated with the CaCO3 mineral shell. Confocal microscopy was used to demonstrate an oil-soluble fluorescent dye is encapsulated in the interior of the emulsion, or both hydrophilic and hydrophobic compounds can be incorporated with the aqueous and hydrocarbon regions of liposomes, respectively. The metastable morphology of the CaCO3 shell enables a pH dependent degradation of the particles, allowing for release of the active agent of interest. These CaCO3-coated microcapsules can be dried down to a powder, while retaining the active agent within the fluidic core, thereby saving in storage and transportation expenses because the large solution phase of the suspension is removed. In conclusion, while dinoflagellates utilize this encapsulation strategy as a protective shell, these biomimetic core-shell microcapsules have a myriad of potential applications because of their inherent environmentally-benign composition and biocompatibility, such as in release of pesticide or fertilizer, in chemical reactions such as release of catalyst of specific reagents, in hair/skin care products for release of conditioner or other compounds, in health care for release of pharmaceutics, or in self-healing composites for release of a sealant during capsule fracture.
M1: Nanomaterials for Biomedical Applications
Monday AM, November 30, 2015
Sheraton, 2nd Floor, Liberty B/C
9:00 AM - *M1.01
Synthesis and Characterization of Bimetallic Noble Metal Nanoparticles for Biomedical Applications
Prem C. Pandey 1
1Indian Institute of Technology(BHU) Varanasi IndiaShow Abstract
We report herein a facile approach to synthesize processable bimetallic nanoparticles (Pd-Au/Au-Pd/Ag-Au/Au-Ag) decorated Prussian blue nanocomposite (PB-AgNP). The presence of cyclohexanone/formaldehyde facilitates the formation of functional bimetallic nanoparticles from 3-aminopropyltrimethoxysilane (3-APTMS) capped respective noble metal ions under desired ratio of hetero noble metal ions. The use of aforementioned reducing agents (3-APTMS and cyclohexanone) also enables the synthesis of polycrystalline Prussian blue nanoparticles (PBNPs). As synthesized PBNPs, Pd-Au/Au-Pd/Ag-Au/Au-Ag enable the formation of nano-structured composites displaying better catalytic activity than that recorded with natural enzyme. The nanomaterials have been characterized by UV-vis, FT-IR and Transmission Electron Microscopy (TEM) with following major findings: (1) 3-APTMS capped noble metal ions in the presence of suitable organic reducing agents [3-Glycidoxypropyltrimethoxysilane (GPTMS), Cyclohexanone and Formaldehyde] are converted into respective nanoparticles under ambient conditions, (2) the time course of synthesis and dispersibility of the nanoparticles are found as a function of organic reducing agents, (3) the use of formaldehyde and cyclohexanone in place of GPTMS with 3-APTMS outclasses the other two in imparting better stability to amphiphilic nanoparticles with reduced silanol content, (4) an increase in 3-APTMS concentrations causes decrease in nanogeometry of nanoparticles (5) simultaneous synthesis of bimetallic nanoparticles under desired ratio of palladium/gold and silver/ gold cations are recorded, (6) cyclohexanone mediated synthesis nanoparticles enable the formation of homogeneous nanocomposite with PBNP as peroxidase mimetic representing potential substitute of peroxidase enzyme. The peroxidase mimetic ability has been found to vary as a function of 3-APTMS concentration revealing the potential role of functional metal nanoparticles in bioanalytical applications.
M3: Poster Session
Monday PM, November 30, 2015
Hynes, Level 1, Hall B
9:00 AM - M3.01
Influence of Laser Structured Pt/Ir Brain Implant Electrodes with Trapezoidal Cross Section on MRI Artefact Size
Johannes B. Erhardt 1 Jochen Leupold 2 Erwin Fuhrer 3 Oliver Gruschke 3 Matthias C. Wapler 1 Juergen Hennig 2 Jan Korvink 3 Thomas Stieglitz 1
1University of Freiburg Freiburg Germany2University Medical Center Freiburg Freiburg Germany3Karlsruhe Institute of Technology Karlsruhe GermanyShow Abstract
Most active implantable medical devices (AIMD) cause contraindication for implanted patients with magnetic resonance imaging (MRI) due to safety reasons (force, heating, imaging artefacts). Artefact reduction is especially relevant to enable imaging in the direct vicinity of implanted devices e.g. for postoperative placement verification and continuous checkup examinations .
Many AIMDs rely on thin film technology, where, depending on the deposition process, the edge of a structure shows various slopes. While the far-field of the magnetic distortion will just be dominated by the dipole that is proportional to the volume, the artefacts of thin films may also highly depend on edge effects. These will depend on the film thickness and at least to higher order also on the slope. While one can easily simulate the magnetic field itself, it is non-trivial how this translates into MR artefacts. Hence, we took an experimental approach to investigate this systematically at the example of Pt/Ir electrodes. For this purpose we developed a process to laser-structure trapezoidal cross sections and compared the artefact size of electrodes featuring various edge slopes.
For sample preparation, we laminated 25 µm thick Pt/Ir foil (Goodfellow) on silicone substrate. Thereafter, we used a Rapid10 picosecond-laser (Lumera) to structure 750 µm in diameter, disc shaped, electrode-like samples with trapezoidal cross section of various angles. Then, the samples underwent MRI examination in a 7 T Bruker Biospec 70/20. For comparison, we fabricated samples with the same slope angles but with constant volume (larger diameter). Finally, samples with rectangular cross section but varying thickness were investigated.
Laser ablation proved to be a reproducible method for structuring Pt/Ir discs with trapezoidal cross section and various slope angles. The MRI examination of these samples (non-constant volume) showed distinct differences in MRI artefact size. However, samples with the same slopes but constant volume showed hardly any difference in MRI artefact size. The samples with rectangular cross section and varying thickness suggested a linear dependency of volume to MRI artefact size.
We show that implant electrode structures with trapezoidal cross section can be fabricated with a laser ablation process. Furthermore, these preliminary investigations suggest that sloped edges have no significant influence on MRI artefact size, whereas the sample volume (thickness) seems crucial, as expected. We conclude, for MRI artefact reduction purposes more effort should be dedicated to reducing metal volume in implants, whereas the structure of the edges and hence the choice of manufacturing process is less critical.
Acknowledgements: This work was funded within the Cluster of Excellence “BrainLinks-BrainTools” by the German Research Foundation (DFG ExC1086).
Zrinzo et al.:WorldNeurosurgery;76(1):164-172(2011)
9:00 AM - M3.02
UV/Ozone Surface Modification for Long-Term Stable Hydrophilic Surface of Polymer Microfluidic Devices
Shogo Uehara 1 Osamu Tsuji 2
1SAMCO Inc. Sunnyvale United States2SAMCO Inc. Kyoto-city JapanShow Abstract
Polymer microfluidic devices are an emerging technology, enabling low-cost and quick clinical diagnostics. The polymer materials used in the devices are generally hydrophobic, and surface modification is required for stable flow in the micro-size channels. There are several techniques for obtaining a hydrophilic surface. Plasma surface modification, especially oxygen plasma treatment, is widely used for this application; however hydrophobic recovery quickly starts after the treatment. Therefore, it is not easy to keep the surface hydrophilic over long time periods. UV/ozone treatment is also a well-known technique for the surface modification. The disadvantage of UV/ozone treatment is that the process is more time-consuming compared to oxygen plasma treatment. Therefore, rapid and effective surface modification processes by UV/ozone treatment need to be developed.
In this presentation, we will describe parameters for rapid and effective surface modification by UV/ozone treatment and then will compare the subsequent hydrophobic recovery with oxygen plasma treatment. The polymer materials chosen in this study were: (1) polymethyl methacrylate (PMMA), (2) cyclic olefin copolymer (COC), (3) cyclic olefin polymer (COP) and (4) polyether ether ketone (PEEK). A UV/ozone cleaner (Model UV-2, SAMCO Inc.) was used for the surface modification. The system is equipped with an ozone generator for higher ozone concentration (30-160 g/m3) and a sample stage heater capable of controlling from ambient to a maximum temperature of 300°C. For evaluation of the wettability of the surface, the static contact angle was measured by the sessile drop method. Then, subsequent hydrophobic recovery was investigated by comparing UV/ozone treated polymer samples with identical samples treated using oxygen plasma. Function groups on the surface before and after UV/ozone treatment were characterized using X-ray photoelectron spectroscopy (XPS).
It was found that employment of ex-situ generated ozone and stage temperature control both contributed to the rapid and effective surface modification of each material. Also, the UV/ozone treatment was optimized for each material and the UV/ozone treated surfaces showed a long-term stable hydrophilic surface for up to 6 months, which was in contrast to the hydrophobic recovery that was seen following oxygen plasma treatment. For the XPS characterization of COP, the sample processed with UV/ozone using ex-situ generated ozone and stage temperature control showed a larger amount of ester functional groups (-COOR), compared to the sample processed with UV/ozone but without ex-situ generated ozone and stage temperature control. We believe that the UV/ozone cleaner equipped with an ex-situ, high-concentration ozone generator and controlled stage heating is superior to traditional UV/ozone cleaners for obtaining a long-term stable hydrophilic surface of polymer materials.
9:00 AM - M3.03
UV-Nanoimprint Lithography as a Tool to Develop Flexible Microfluidic Devices for Electrochemical Detection
Yiliang Zhou 1 Juhong Chen 1 Kenneth R Carter 1 James J. Watkins 1 Sam R. Nugen 1
1Umass Amherst Amherst United StatesShow Abstract
Research in microfluidic biosensors has led to dramatic improvements in sensitivities. Very few examples of these devices have been commercially successful, keeping this methodology out of the hands of potential users. In this study, we developed a method to fabricate a flexible microfluidic device containing electrowetting valves and electrochemical transduction. The device was designed to be amenable to a roll-to-roll manufacturing system, allowing a low manufacturing cost. Microchannels with high fidelity were structured on a PET film using UV-NanoImprint Lithography (UV-NIL). The electrodes were inkjet-printed and photonically sintered on second flexible PET film. The film containing electrodes was bonded directly to the channel-containing layer to form sealed fluidic device. Actuation of the multivalve system with food dye in PBS buffer was performed to demonstrate automated fluid delivery. The device was then used to detect Salmonella in a liquid sample.
9:00 AM - M3.04
Fabrication and Characterization of Dexamethasone-Loaded Biodegradable Nanofibers and Conducting Polymers Produced via Electrospinning and Electrochemical Polymerization for Neural Microelectrodes
Milad Khorrami 1 Mohammad Reza Abidian 2 1 3
1Pennsylvania State University State College United States2Pennsylvania State University State College United States3Pennsylvania State University State College United StatesShow Abstract
Anti-inflammatory agents have been used widely for drug delivery to neural tissue. A considerable amount of research has been dedicated to improve the biocompatibility and efficacy of the neural microelectrodes. However, there are some challenges such as (1) the burst effect of drug in the brain and (2) the huge amount of neuronal killing zone around the implanted electrode in the brain tissue. To overcome these challenges, we have proposed a method for fabrication and sustained release of drug using anti-inflammatory agent dexamethasone (DEX)-loaded within hybrid biodegradable nanofibers and conducting polymers.
The objective of this study was to develop a novel method for encapsulation of DEX within aligned conducting polymer nanotubes using electrojetting of aligned poly (lactic-co-glycolic acid) (PLGA) nanofibers and electrochemical polymerization of conducting polymer poly(pyrrole) (PPy). Briefly, DEX-PLGA solution was electrospun on Au substrates followed by electrochemical polymerization of PPy. After fabrication of aligned DEX-loaded PLGA nanofibers, PPy was electrodeposited on Au substrates and around nanofibers from a solution containing 0.2 M pyrrole and 0.2M sodium-p-styrenesulfonate (PSS) using and applied current density 0.5mA.cm-2 in 6 different deposition time from 1min to 6min. Surface morphology of aligned PLGA nanofibers and PPy nanotubes were characterized using optical microscopy and field emission scanning electron microscopy. Cyclic Voltammetry (CV) has been employed to actuate the DEX-loaded PPy nanotubes in order to increase the amount of DEX. We hypothesize that the parameters of CV such as voltage (from 0.2V to 1V), scan rate (from 50mv/s to 400mv/s, and number of cycles (from 1 to 50 cycles) have direct influence on the rate of DEX release. DEX-loaded PPy nanotubes were compared for both stimulated and unstimulated conditions. For quantification Dex release, we used UV spectrophotometry and detected DEX at wavelength 242nm. For the future study we will control the growth of PPy around the aligned PLGA nanofibers. It is anticipated that by increasing the thickness of PPy coating around the PLGA nanofibers, the amount of DEX release will be modulated. Our developed technique can be potentially applied in neural microelectrode for neural recording and/or stimulation.
9:00 AM - M3.05
Optical Waveguide Biosensors for Highly Sensitive and High-Throughput Applications
Ikuo Uematsu 1 2 Masaaki Hirakawa 2 Kenya Uchida 2 Kayoko Oomiya 2 Hidetoshi Matsumoto 1
1Tokyo Institute of Technology, Department of Organic and Polymeric Materials Tokyo Japan2Toshiba Corporation Yokohama JapanShow Abstract
In the field of clinical diagnostics, highly sensitive sensing system is strongly required to quickly obtain diagnostics results during medical treatments or to continuously monitor a very small amount of specimens of subcutaneous tissue fluid. In the present study, highly sensitive optical waveguide biosensors were designed by using the combination of dye and polymer-enzyme complex. Optical light waveguide can detect the optical change in the vicinity of the guide surface with high sensitivity due to the evanescent wave scattering. The optical change depends on the quantity of color development of dye in the sensing membranes formed on the optical waveguide. The sensing membranes, composed of dye, enzymes, and biocompatible polymers, were prepared by solution-coating on the optical waveguide. Herein, we used 3, 3&’, 5, 5&’-tetoramethylbenzidine (TMBZ) as a dye, glucose oxidase (GOD) and peroxidase (POD) as enzymes, and carboxymethyl cellulose (CMC) as a binder, and phosphatide polymer for protection of biological activity of enzymes. Then we investigated effects of the composition and structure of sensing membranes on the enhancement of sensitivity and response speed. The developed glucose sensors are up to 20 times more sensitive than the conventional light waveguide glucose sensors and can detect 0.1g/L glucose in 60 seconds. For the further improvement in sensitivity, microporous sensing membranes were fabricated by using electrospraying techniques. The electroprayed sensing membranes showed 40 % higher sensitivity than nonporous sensing membranes. These results show that both the composition (e.g., polymer-enzyme complex) and structure (e.g., active surface area) of sensing membrane are crucial factors for highly sensitive and high-throughput optical waveguide biosensors.
9:00 AM - M3.06
Thermal Annealing Process: A Potential Technique to Prepare Hydrophilic Titanium Surface for Implant Applications
Suwimon Boonrungsiman 1 Panida Prompinit 1 Pongtanawat Khemthong 1 Tuksadon Wutikhun 1 Alongkot Treethong 1 Mati Horprathum 2 Narong Chanlek 3 Rawiwan Maniratanachote 1 Sirapat Pratontep 4 Annop Klamchuen 1
1National Nanotechnology Center (NANOTEC), NSTDA Pathum Thani Thailand2National Electronics and Computer Technology Center (NECTEC), NSTDA Pathum Thani Thailand3Synchrotron Light Research Institute Nakhon Ratchasima Thailand4King Mongkutrsquo;s Institute of Technology Ladkrabang Bangkok ThailandShow Abstract
A failure of Titanium (Ti) implant is often caused by a lack of strong interaction and between implant surfaces and surrounding bones. Therefore, there have been attempts to improve Ti surface properties including modification of surface roughness and hydrophilicity. Several surface modification techniques, such as sandblasting and acid etching (SLA), anodizing and laser, have been used to improve cell adhesion and osteointegration of the implants. These techniques, however, are expensive, time-consuming, and some procedures require chemical process.
Here we demonstrated a new approach to modify Ti surface using thermal annealing in air. The Ti plates were annealed at 300,400, 500 and 600 #870; C and investigated their surface structures and chemical compositions as a function of temperatures. Annealed Ti surface were observed alterations of both morphologies and chemical compositions as a TiO2 layer formed on surface. This leaded to an improvement of wettability of annealed Ti surface compared to untreated Ti surface, evidenced by a reducing of a contact angle from 89±5 #870; of untreated Ti specimens to 22 -30 #870; of the annealed Ti surfaces. The phase compositions and the oxidation depth of TiO2 layers were found to be strongly depended on oxidation temperature. At 300 #870; C, Ti metal was a dominant phase of the Ti surface, and an increasing temperature increased the rutile phase composition.
In addition, mouse osteoblasts (MC3T3) exhibited a normal growth on these modified Ti surface compared to the polylysine coated tissue culture plates. The influences of these surface structures and chemistry on the cell proliferation and adhesion are being investigated in order to determine the optimum surface treatment condition. The thermal annealing process could be a potential technique to prepare Ti implant due to its low cost, simplicity and capability to modify surface structure, chemical compositions and hydrophilicity.
9:00 AM - M3.07
Realization of Smart Contact Lenses for Wireless Healthcare System
Beomho Mun 1 Do Hee Keum 2 Hyemin Kim 2 Keon-Jae Lee 1 Seok Hyun Yun 3 Sei Kwang Hahn 2
1KAIST Daejeon Korea (the Republic of)2Pohang University of Science and Technology (POSTECH) Pohang Korea (the Republic of)3Massachusetts General Hospital and Harvard Medical School Cambridge United StatesShow Abstract
Nowadays, smart contact lens have attracted significant interest for diagnostic and drug delivery applications to ocular diseases as a minimally invasive platform. Here, we fabricated a smart contact lens consist of biosensor, drug delivery system, communication circuitry for the treatment of ocular diseases or diabetes. The biosensing, drug delivery systems, communication circuitry were integrated on a wireless powered contact lens. For the diagnosis of ocular diseases, tear glucose content was measured as a non-invasive alternative for the blood glucose content monitoring. The biosensor belong to electrochemical amperometric sensor contained Pt electrode immobilized with glucose oxidase. When glucose binds to glucose oxidase, hydrogen peroxide is produced and oxidized on the electrode generating electrons. From the current, we measured the amount of glucose in the tear. For the drug delivery system, we fabricated thin film Au membrane on flexible SU-8 drug reservoirs and molded to contact lens. Applying pulse of electrical current can remove each Au membrane on reservoir by exploit the electrochemistry of Au to AuCl4- in NaCl solution. Finally, the WiTricity power transfer system fabricated on smart contact lens to operate the sensors, drug delivery systems, and communication circuitry. This smart contact lens can be exploited for various ubiquitous healthcare applications.
9:00 AM - M3.08
Enhancement of Directional Cell Migration and Patterning on Polystyrene Nanomachined by Direct Multiphoton Ablation Lithography
Sangmo Koo 1 Hojeong Jeon 2 Costas P Grigoropoulos 1
1Univ of California-Berkeley Berkeley United States2Korea Institute of Science and Technology Seoul Korea (the Democratic People's Republic of)Show Abstract
Multiphoton ablation lithography is used for material surface modification and treatment in order to control biofouling by cells. We fabricated isometric and gradient ablated crater patterns with a variety of geometries and spatial arrangements on tissue culture polystyrene (TCPS) using direct laser writing technique. Varying the shape (i.e. width and depth) and the spacings (i.e. the spatial density) of ablated features could alter the focal adhesion (FA) dimensions and distributions, hence effectively guiding the cell migration and patterning. On isometric patterns, we were able to identify the surface ligand density threshold for repellent migration . Below this threshold, FAs of fibroblast do not exhibit specific interaction with ablated patterns. In the low nanocrater density region, cells could establish stable FAs. In contrast, in the high nanocrater density region, they formed nascent FAs. On the gradient pattern, this difference enhanced migration from lower spacing (i.e. denser) pattern toward more favorable region with larger spacing (i.e. more sparse) patterns providing increased planar surface area for stable focal adhesion formation. This persistent migration created different cell patterns, such as linear stripes. To further investigate the interaction between TCPS substrate and cells, we showed the effect of extracellular protein absorption on cell patterning using quartz crystal microbalance with dissipation (QCM-D).. Different patterned arrays of RGD peptide ligands induced cell migration in a density dependent manner. This laser-treated technique can be applied to various materials and a wide range of applications such as breast implants, electrode leads on pacemakers and defibrillators and orthopedic implants representing a significant health care cost and risk. Especially noteworthy is that the surface modification using femtosecond laser on TCPS does not induce chemical alteration. Cell patterning on TCPS is in essence a simple method, that is applicable to diverse experiments as an effective tool for mechanotrasduction studies in the context of regenerative medicine.
9:00 AM - M3.09
One-Step Synthesis of Heterogeneous Multifunctional Nanoparticles for Biomedical Applications via Scalable Flame Spray Pyrolysis
Fabian Starsich 1 Alexandra Vollenweider 1 Ann M. Hirt 2 Sotiris E. Pratsinis 1
1ETH Zurich Zurich Switzerland2ETH Zurich Zurich SwitzerlandShow Abstract
The production of heterogeneous nanoparticle systems in a single process step is of profound interest for various applications. Multifunctional nanomaterials are attractive for biomedics, where multiple diagnostic modalities or the possibility of combined therapy and diagnosis (theranostics) via a single agent are sought out. Although the production of various heterogeneous systems has been reported previously their large scale synthesis still represents a key challenge. This gains even more importance if the materials which are to be combined heterogeneously also form homogeneous alloyed or doped states. Here, the one-step synthesis of a heterogeneous Zn0.4Fe2.6O4 / Gd2O3 multi-component systems via dry and scalable multi-spray aerosol technology is reported. A precise process control is shown, which allows the fine tuning of the resulting material composition. The produced materials are compared to their homogeneously mixed counterpart. Special emphasis is put on improved magnetism and increased efficiency as magnetic resonance imaging contrast agents.
9:00 AM - M3.10
Doping of Flame-Made ZnO for Enhanced Acetone Sensing in Breath Analysis
Andreas Guentner 1 Nicolay Pineau 1 Donovan Chie 1 Sotiris E Pratsinis 1
1ETH Zurich Zurich SwitzerlandShow Abstract
More than 387 million people suffer from diabetes making it one of the most widespread chronic diseases worldwide.1 For 2035, it is projected that their number will increase to 592 million.1 Breath acetone is a promising marker that could indicate diabetes already in an early-stage and help monitoring its progression. In fact, exhaled acetone levels are elevated significantly from 300 - 900 ppb2 for healthy to above 1800 ppb for uncontrolled diabetes.3 Chemo-resistive gas sensors offer great advantages for sensing such breath markers such as simple operation, high miniaturization potential, low power consumption and production cost.4 Quite promising for acetone is ZnO for its high analyte sensitivity.5 However, drawbacks that hinder its application are the lack of selectivity towards other breath compounds5 and the high cross-sensitivity to relative humidity (RH),6 i.e. for breath ~90% RH.7
Here, ZnO was doped during its synthesis to overcome these drawbacks. So pure and doped ZnO nanoparticles were produced by flame spray pyrolysis (FSP) and directly deposited onto sensor substrates forming a highly porous sensing film. Applied dopants improved the acetone selectivity against breath-relevant ethanol, NH3, CO and NO. Additionally, the strong interference of humidity was reduced. This optimized sensor was capable to selectively detect even ultra-low acetone levels of 5 ppb, more than sufficient for breath analysis. Furthermore, response times were lower than 1 min enabling real-time monitoring. In conclusion, doped ZnO sensors showed high potential for implementation in an easy, inexpensive, portable and non-invasive breath acetone analyzer.
(1) IDF Diabetes Atlas: Update 2014, International Diabetes Federation, Brusseles, 2014.
(2) Diskin, A.M.; Spanel, P.; Smith, D. Physiol Meas.2003, 24, 107-119.
(3) Deng, C.; Zhang, J.; Yu, X.; Zhang, W.; Zhang, X. J Chromatogr B2004, 810, 269-275.
(4) Righettoni, M.; Amann, A.; Pratsinis, S.E. Mater. Today2015, 18, 163-171.
(5) Zeng, Y.; Zhang, T.; Yuan, M.; Kang, M.; Lu, G.; Wang, R.; Fan, H.; He, Y.; Yang, H. Sens. Actuators B2009, 143, 93-98.
(6) Zhang, Y.; Yu, K.; Jiang, D.; Zhu, Z.; Geng, H.; Luo, L. Appl. Surf. Sci.2005, 242, 212-217.
(7) Zehentbauer, G.; Krick, T.; Reineccius, G.A. J. Agric. Food. Chem.2000, 48, 5389-5395.
9:00 AM - M3.11
Antiviral Activity of Silver Nanoparticles Immobilized onto Textile Fabrics Synthesized by Radiochemical Process
Satoshi Seino 1 Yasuo Imoto 2 Tomoki Nishida 2 Tomoya Kosaka 1 Takashi Nakagawa 1 Takao A. Yamamoto 1
1Osaka University Suita Japan2Japan Textile Products Quality and Technology Center Kobe-city JapanShow Abstract
As the pathogenic viruses are always major threat to the human society, various kinds of antiviral agents are widely studied by many researchers. Of the various kinds of antiviral agent available, silver nanoparticles have received significant attention. However, inhibition mechanism of silver nanoparticles against viruses is not thoroughly understood yet. Understanding the inhibition mechanism of silver nanoparticle is essential for their medical uses. With conventional studies, silver nanoparticles used in antiviral studies are usually used. Colloidal silver nanoparticles are usually coated with surfactants to control their size and stability in solution system, which make difficult to discuss their surface effect against viruses. Also, effect of free silver nanoparticles on virus-infected cells sometimes make difficult to understand the mechanism.
This paper presents a new technique for synthesizing silver nanoparticles immobilized on textile fabrics using a radiochemical process. As no surfactants or polymers are applied in the synthesis process, the silver nanoparticles on textile fabrics have bared surface, which would interact with viruses directly. The silver nanoparticles are firmly immobilized on support textile fabrics and their effects on virus-infected cells are negligible. The antiviral activities of silver nanoparticles with bared surfaces were investigated.
Samples of the textile fabrics were then immersed in AgNO3 solution. Following immersion, any excess solution was removed by centrifugal dewatering. The resulting AgNO3-soaked textile fabrics were irradiated with a high-energy electron beam (4.8 MeV, 40 kGy). Radiochemical species generated by the irradiation reduce Ag ions to form metallic Ag nanoparticles. The resulting immobilized silver nanoparticles were characterized by TEM, ICP-AES and XAS, and their antiviral properties are discussed. These nanoparticles are firmly immobilized on the surface of a support textile fabric without the need for any binder or surfactant. Ag on textile fabrics exist as metallic state, which was confirmed by XAS analysis. TEM observation revealed that small Ag particles of about 2-4 nm were observed together with relatively large particles of more than 10 nm.
The antivirus test was performed basically following the ISO18184. Influenza virus and feline calicivirus were used. Concentration of EMEM (Eagle's Minimal Essential Medium) buffer was controlled as experimental parameter. With low medium concentration, Ag nanoparticles showed antiviral activity depending on the amount of Ag on textile fabrics. However, antiviral activities of Ag nanoparticles were not observed with high medium concentrations. Antiviral activity of the Ag nanoparticles are discussed on the basis of Ag nanoparticle amount and their chemical states.
9:00 AM - M3.12
Nanowires and Microfilters Based Intergrated Microfluidic Devices for Immunoassay Assay
Nhi Doan 1 Liangliang Qiang 1 Zhe Li 1 Santhisagar Vaddiraju 2 Gregory Bishop 1 James Rusling 1 Fotios Papadimitrakopoulos 1 2
1Univ of Connecticut Storrs United States2Biorasis Inc. Storrs United StatesShow Abstract
Integrated microfluidic devices with nanosized array electrodes and microfiltration capabilities can greatly increase sensitivity and enhance automation in immunoassay devices. In this contribution, we utilize the edge-patterning method of thin aluminum (Al) films in order to form nano- to micron-sized gaps. Evaporation of high work-function metals (i.e., Au, Ag, etc.) on these gaps, followed by Al lift-off, enables the formation of electrical uniform nanowires from low-cost, plastic-based, photomasks. By replacing Al with chromium (Cr), the formation of high resolution, custom-made photomasks that are ideal for low-cost fabrication of a plurality of array devices were realized. To demonstrate the feasibility of such Cr photomasks, SU-8 micro-pillar masters were formed and replicated into PDMS to produce micron-sized filters with 3-4 mu;m gaps and an aspect ratio of 3. These microfilters were capable of retaining 6 mu;m beads within a localized site, while allowing solvent flow. The combination of nanowire arrays and micro-pillar filtration opens new perspectives for rapid R&D screening of various microfluidic-based immunoassay geometries, where analyte pre-concentration and highly sensitive, electrochemical detection can be readily co-localized.
9:00 AM - M3.13
A Nanoliter-Droplet Virtual Well Plate for Detecting Selectively Adsorbed Peptides and Proteins with High Sensitivity
Xiaoxiao Chen 1 Yang Liu 2 QianFeng Xu 1 Jing Zhu 2 Sebastien Poget 2 Alan Lyons 2 1
1ARL Designs LLC New York United States2College of Staten Island and The Graduate Center of the City University of NY New York United StatesShow Abstract
Understanding biological pathways is essential for developing strategies for treating diseases and developing new drugs. The mainstay for probing these pathways is the microwell plate, a standardized array of containers in which a number of biological tests can be conducted and analyzed in parallel, thereby increasing throughput and accelerating scientists&’ ability to collect and analyze data. As technology has advanced, and the cost of reagents has increased, the size of the wells has decreased, such that 1536 wells, molded into a single plastic carrier, are commercially available. Microarrays are gaining in popularity as they are able to further increase the density of test sites and reduce the quantities of reagents required. However as microplates and microarrays advance, costs are rapidly increasing. Cost drivers include the increased precision required to dispense the small volumes of solutions consumed, the tolerances of both the plates and dispensing systems used, and the microfluidic systems needed for microarrays.
In this paper, we describe a new microplate technology which we call the nanoliter-droplet based Virtual-Well Microplate (nVWMP). Using hydrophilic glass pedestals, the surface works in conjunction with a simple dispensing system to precisely deposit nanoliter volumes of biological solutions in precise locations on the surface. Because wetting is controlled by a combination of surface chemistry and surface geometry, the nVWMP design relieves the tight tolerances required in conventional dispensing systems, lowering costs and increasing precision. Droplets that measure 28 nL can be dispensed with a precision of 2% using a simple robot costing less than $1,000.
The glass surface of the nVWMP can be chemically modified to selectively absorb peptides and proteins that are subsequently detected either by fluorescence microscopy or MALDI-TOF. We describe the modification of the surface with a combination of polyethylene glycol (to reduce non-specific protein absorption) and biotin moieties to selectivity bind NeutrAvidin from a solution containing BSA at concentrations as low as 0.1 micro-grams/mL (total of 8.33 x 10.7 nanomoles of NeutrAvidin). MALDI-TOF was used with this geometry to detect NeutrAvidin with a sensitivity of 4 attomoles of protein. In another example we used a glass surface coated with a Ni+-chelate resin to selectively bind the KcsA ion channel protein. The nVWMP so prepared was shown to selective bind the TX7335 peptide from snake venom.
9:00 AM - M3.14
Design and Characterization of Conformal Electrodes Based Biosensor for Cardiac Biomarker Detection
Vikramshankar Kamakoti 1 Anjan Panneer Selvam 1 Shalini Prasad 1
1Univ of Texas-Dallas Richardson United StatesShow Abstract
The design of sensitive diagnostic biosensor is of crucial significance for early detection of cardiac diseases. This is achieved by measuring the concentration of the biomarkers of interest. The binding of target antigens with the antibodies immobilized on the electrodes and the subsequent changes in the impedance are the driving factors for the detection of the biomarkers. The interactions at the electrode-electrolyte interface result in the modulation of the height of the electrical double layer (EDL). This theory of tuning the EDL is enhanced with the use of conformal electrodes. Hence, we use the porous structures as the substrates for electrode material deposition. The material properties of the electrode has a significant effect on the sensor performance. Thus, it is imperative to characterize the material properties of the electrode material and the sensor substrate.
Our initial experimental approach was focused on characterization of the surface of the sensor substrate after the electrode material deposition. We chose Molybdenum as the electrode material to investigate its properties for biosensing applications as there have been prior research works supporting the use of Molybdenum in biosensing applications. We analyzed the changes in the impedance at every step of the immunoassay which was built on the electrode substrates. The performance of the sensor was tested for multiple concentrations of the target antigen in ranges required for early disease detection. The ranges of the doses of the proteins were tested from ng/ml to µg/ml. The choice of buffer was varied and its effect on the sensor performance would be analyzed. The performance of the conformal electrode sensor was compared with that of planar electrodes. The electrode dimensions were varied and its effect were analyzed. The effect of variation of electrode dimensions and its corresponding correlation to electric field distribution were analyzed through finite element modelling (FEM) methods. The feedback obtained from the FEM results was incorporated in the design of experiments to validate the FEM analysis.
9:00 AM - M3.16
Silver Nanoparticle Films For Plasmon-Enhanced Optically Stimulated Luminescence: Towards Development of Radiation Detectors and Dosimeters for Medical Applications
Eder Jose Guidelli 1 Ana Paula Ramos 1 Oswaldo Baffa 1
1University of Sao Paulo Ribeirao Preto BrazilShow Abstract
Plasmon enhancement of luminescence close to noble metal nanoparticles films is a powerful tool largely employed in many different areas. Here we investigate the possibility of using the plasmonic properties of silver nanoparticles (AgNP) films to get plasmon enhanced optically stimulated luminescence (OSL), which is a technique largely employed for radiation detection and dosimetry in many medical procedures. Silver nanoparticles/chitosan films were produced using the layer-by-layer technique and characterized by UV-Vis spectroscopy, Atomic Force Microscopy, and Fourier Transform Infrared Spectroscopy. We collected the Optically Stimulated Luminescence signal from irradiated NaCl deposited over nanoparticles films with 3, 5 and 10 AgNP/Chitosan layers. There is a strong enhancement of the optically stimulated luminescence intensity for NaCl deposited over the AgNP films compared to NaCl deposited over glass, and the maximum enhancement is obtained for the film with 10 AgNP/Chitosan layers. The enhancement can also be controlled by varying the distance between the luminescent crystals and the silver nanoparticle film, which leads to a maximum OSL intensity for a 15 nm distance. Results will be further discussed in terms of the different film properties. These findings may lead to a new class of highly sensitive and miniaturized radiation detectors.
9:00 AM - M3.18
Characterization of Elastic Modulus of Polymeric Membranes Using Microfluidics
Jen-Huang Huang 1 Ayesha Arefin 1 Leyla E Akhadov 1 Rashi S Iyer 1 Pulak Nath 1
1Los Alamos National Lab Los Alamos United StatesShow Abstract
Elastically deformable membranes have found different applications in biomedical devices such as micro-valves or Organs-on-a-chip. The elastic modulus of these membranes is an important parameter to determine their functionality. Typically, the elastic modulus is characterized by bulging tests, interferometry, or indentation techniques [1, 2]. However, all these techniques require specialized tools (e.g. microscopes, interferometers, or atomic force microscopes, respectively) to carry out the characterization. In this work, we present a simple, microfluidic platform to rapidly and accurately measure the elastic modulus of polymeric membranes.
The device is composed of two compartments. One of the compartments is connected to a microfluidic channel. The microfluidic channel is designed such that any movement of a dye solution is visible with the naked eye. The second compartment is connected to a syringe and a pressure transducer. The membrane under consideration can be placed and sealed between the two compartments. The first compartment is partially filled with a dye solution. The membrane is deformed by applying pressure through the second compartment using the syringe. The applied pressure is recorded by the pressure transducer. As the membrane is deformed due to the applied pressure, it displaces the fluid/dye inside the microfluidic channel. The extent of deformation (i.e. bulging) of the membrane is indicated by the displacement of the dye meniscus inside the microfluidic channel. The width of the microfluidic channel was set to 550 mu;m for the ease of tracking the meniscus displacement. Measurement of elastic modulus was demonstrated using a 35 mu;m Polydimethylsiloxane (PDMS) membranes and 10 micron Polyurethane (PU) membranes. The displacement of the meniscus changed linearly with the applied pressure. Young&’s elastic modulus was calculated for multiple independently fabricated membranes. The sensitivity of this platform can be tailored to measure the elastic modulus of membranes with very small deflection. For example, by designing the device with a membrane diameter of 8 mm, and microfluidic channel height of 250 mu;m, it is possible to measure membrane deflection as small as 10 mu;m with the naked eye.
We have demonstrated the ability to characterize the elastic modulus of elastic membranes using a simple microfluidic platform. In spite of its simplicity, our platform should be able to perform sensitive measurements with a wide range of polymeric membranes applicable for many biomedical devices.
Ref:  Ping Du, Hongbing Lu and Xin Zhang (2009). Measuring the Young&’s Relaxation Modulus of PDMS Using Stress Relaxation Nanoindentation. MRS Proceedings, 1222, 1222-DD02-03 doi:10.1557/PROC-1222-DD02-03.  Y. Xiang, X. Chen and J.J. Vlassak (2005). Plane-strain Bulge Test for Thin Films. Journal of Materials Research, 20, pp 2360-2370. doi:10.1557/jmr.2005.0313.
9:00 AM - M3.19
Electrospinning Nano- and Mirco-Scale Size Poly(4-vinphylpridine) Fibers Loaded with Graphene Nano Platelets(GNPs)
Linxi Zhang 1 Chung-Chueh Chang 1 2 Miriam Rafailovich 1 3 Amanda Klestzick 4
1Stony Brook University Stony Brook United States2Stony Brook University Stony Brook United States3Stony Brook University Stony Brook United States4Salanter Akiba Riverdale Academy Riverdale United StatesShow Abstract
Many studies have shown that graphene has ability to enhance the stem cell proliferation and mediate differentiation linages. Graphene-polymer composite materials have been popularized in tissue engineering due to the outstanding thermal, electrical and mechanical properties of graphene. Currently, however, most of the studies focus on 2-D structured films which hardly represent the real conditions of scaffolds in vivo environment. In addition, dispersion of graphene in polymer matrix has always been challenging since the graphene tends to aggregate. In our study, we have successfully introduced graphene nanoplatelets (GNPs) into poly(4-vinphylpridine) (P4VP) matrix and fabricated nano- and micro-scale size fibers by using a cost-effective technique, electrospinning. SEM and TEM reveal uniform defect-free fiber structures and good dispersion of graphene inside the fibers. DSC and AFM indicate the enhancement of physical properties. We have also examined the biocompatibility of electrospun 3-D scaffolds of GNPs-P4VP nano- and micro-fibers with dental pulp stem cells (DPSCs). Our results show that the cells can accelerate proliferation to respond to the existence of GNPs even though cells have no direct contact with GNPs. EDAX together with SEM reveals a deposition of mineralized calcium matrix on the fiber scaffolds after 28-day incubation, which has possibly been caused by cell differentiation induced by fibrous scaffolds. In this study, we demonstrated an efficient approach to manufacture the graphene loaded polymer scaffolds which showed great dispersion of graphene, good physical properties and promising potential to promote DPSCs proliferation and differentiation.
The research was supported in part by the NSF-INSPIRE program. Part of research was achieved in ThINC facility at Advanced Energy Center.
9:00 AM - M3.20
Conformally-Micromolded Microneedle Drug Eluting Balloon for Endovascular Drug Delivery
Kang Ju Lee 1 Seul Gi Lee 1 Jung Sun Kim 1 WonHyoung Ryu 1
1Yonsei University Seoul Korea (the Republic of)Show Abstract
Endovascular drug delivery system based on drug eluting balloon (DEB) is an innovative approach to reduce stenosis or neointimal formation as well as to avoid the possibility of in-stent-restenosis (ISR). Even though DEB technology has demonstrated safety and efficacy in preclinical and clinical studies, they are still limited in terms of the efficiency of drug delivery. DEBs are likely to lose drug due to blood flow during the delivery of the DEBs to target region in blood vessels. This loss of drug to the blood stream might induce the unwanted side effect of anti-proliferative drug such as paclitaxel at other tissue locations. Furthermore, in case of ISR, reliable contact is extremely difficult to make between the drug-coated surface of DEBs and diseased tissue under stent struts. Therefore, local and concentrated drug delivery to the tunica media of blood vessel with minimal drug loss and reliable contact to the vascular tissue region with ISR are highly desired. Microneedles (MNs) have been extensively investigated in the field of drug delivery especially for transdermal or ocular administration. Recently, we have demonstrated the multi-fold enhancement of drug delivery efficiency of perivascular drug delivery by developing perivascular MN cuffs that contained an array of MNs in our rabbit abdominal aorta models. The results showed two orders of magnitude enhancement in drug delivery and homogeneous distribution of drugs within tunica media layers. In this work, we developed MN drug eluting balloon (MNDEB) that can effectively deliver drug to the endothelium from the interior of blood vessels without any surgical procedure. An array of 40 mu;m tall MNs was fabricated by KOH chemical wet etching. Then, the MN shape was replicated to PDMS and finally SU-8 MNs shaped on the surface of MNDEB. This dual-step replication molding on the curved surface of DEB was performed by wrapping the PDMS mold on a pressurized balloon and curing the SU-8. The MNDEB was uniformly coated with a drug/carrier formulation containing a fluorescent model drug, rhodamine B. Afterwards, MNDEB angioplasty was performed with rabbit artery in vivo. No deformation or damage of the structure of MN array was observed after the animal study. No visible inflammation was observed when the MNDEB was applied. The animal study was performed with DEB only, DEB with drug coating, MNDEB with drug coating cases. Drug distribution within the vascular tissue samples was analyzed with the cryo-sectioned tissue samples after 2 day follow-up. Higher and more concentrated fluorescent signal was observed for the samples treated with MNDEBs. This confirms the enhanced endovascular drug delivery of MNDEB.
9:00 AM - M3.21
Calcium Phosphate with High Specific Surface Area Synthesized by a Reverse Micro-Emulsion Method
Tomoaki Sugiyama 1 Syusuke Akiyama 1 Toshiyuki Ikoma 1
1Tokyo Institute of Technology Meguro-ku JapanShow Abstract
Calcium phosphate such as dicalcium phosphate anhydrate (DCPA), dicalcium phosphate dihydrate (DCPD) or hydroxyapatite (HAp) shows good biocompatibility and is a candidate of drug delivery carriers. A reverse micro-emulsion method has been investigated to control their crystal morphology in the nanometer region and to increase specific surface area. This study investigated the effect of mixing ratio of two surfactants on crystalline phases and specific surface area of calcium phosphate synthesized by a reverse micro-emulsion method. The nonionic surfactant with hydroxyl groups, tween80 (T) and the cationic surfactant, aliquate336 (A) were mixed into kerosene as an oil phase at the different T/A ratios, in which the amount of aliquate336 was fixed. A di-ammonium hydrogen phosphate solution including phosphoric acid to control pH at 4.0 and a calcium nitrate solution were adjusted, which were separately added into the kerosene. Both the emulsions were then mixed at the same volume and the Ca/P ratio of 1.0 and stirred for 24 hours. The products were centrifuged and washed with ethanol and distilled water. The crystalline phase was characterized with XRD and the specific surface area was measured by a BET method. The crystalline phases were depended on the T amounts; pure DCPD with the specific surface area of 6.7 to 12 m2/g was obtained at the T/A ratio of 4, the mixture of DCPD and DCPA with that of 48 to 162 m2/g was at the ratio of 5 to 8, and a low crystalline HAp with 163 m2/g was at the ratio of 9. These specific surface areas of calcium phosphate were apparently higher than those prepared with a wet method. The change of crystalline phases would be explained as follows; the increase of T amount decreased the micro-emulsion sizes to reduce bulk water to be DCPA, and increased the pH to precipitate HAp nanocrystals.
9:00 AM - M3.22
The Effect of Temperature on Self-Assembled Peptide at Water-Graphite/MoS2 Interface
Linhao Sun 1 Morio Isoda 1 Mehmet Sarikaya 2 Yuhei Hayamizu 1
1Tokyo Institute of Technology Tokyo Japan2University of Washington Seattle United StatesShow Abstract
Biomolecular self-assembly at water/solid interface is being paid wide attention due to the applications in biosensors, nano-devices and medical treatments. Among many kinds of biomolecules, peptide is a unique candidate to modify properties of solid surfaces because of its short sequence and specific binding affinity to solid surfaces. Some specific peptides have been demonstrated to have an ability of self-assembly into long-range ordered structures on solid surfaces, which results into control of solid surface characteristics. The self-assembly is carried out by just placing a droplet of peptide aqueous solution on a solid surface at room temperature. In order to have a good understanding about peptide self-assembly process, the physical parameters relevant to the self-assembly behavior including concentration, incubation time, solvents have been studied so far. Temperature is also an important factor, but not fully understood yet.
In this work, we employed graphite binding peptide and its mutants [1-2] to gain a knowledge of the temperature effect on their self-assembly on graphite surface. We also investigated on MoS2, another layered material which is more suitable for biosensors due to its semiconducting property. We found that temperature sensitively affects the adsorption and diffusion rate of peptides on the surfaces, which can be seen in the ratio of ordered phase and disordered phase of self-assembled peptides. The coverage of peptides on solid surfaces was adjusted as well. Furthermore, we found that the temperature can modify the conformation of peptides observed by the various heights of peptides and multiple kinds of ordered structures with different molecular recognitions.
Controlling Self-Assembly of Engineered Peptides on Graphite by Rational Mutation. Christopher R. So, Yuhei Hayamizu, Mehmet Sarikaya. ACS Nano, 6, 1648 (2012).
Controlling the surface chemistry of graphite by engineered self-assembled peptides. Dmitriy Khatayevich, Yuhei Hayamizu Mehmet sarikaya, Langmuir, 28, 8589 (2012)
9:00 AM -
M3.15 moved M4.09
9:00 AM -
M3.17 moved M8.07
M1: Nanomaterials for Biomedical Applications
Monday AM, November 30, 2015
Sheraton, 2nd Floor, Liberty B/C
9:30 AM - M1.02
DELOS-SUSP Process: Exploiting Compressed CO2 for the Production of Bio-Active Nanovesicles at Industrial Level
Natascia Grimaldi 1 Elisa Elizondo 1 Lidia Ferrer-Tasies 2 3 Maria Aguado 2 3 Dolores Bueno 2 3 Antonio Ardizzone 2 3 Elisabet Gonzalez 2 3 Santiago Sala 3 2 Nora Ventosa 2 3 Jaume Veciana 2 3
1Campus Universitari de Bellaterra Cerdanyola del Vallegrave;s Spain2Campus Universitari de Bellaterra Cerdanyola del Vallegrave;s Spain3CIBER de Bioingenieriacute;a, Biomateriales y Nanomedicina (CIBER-BBN) Madrid SpainShow Abstract
Nanotechnology applied to the Medicine is providing new tools to the current therapeutic and diagnostic approaches because it offers the opportunity of winning some of the open challenges in the field. Currently, the demand is for dual or multiple-mode uptaking, protecting, stabilizing, enhancing and/or transporting functional payloads, such as two or more therapeutics, or therapeutics and contrast agents. Liposomes and in general vesicles, have shown to be one of the most promising supramolecular assemblies for delivering bioactives and some liposome-based-formulations are already present on the market. However, their overspread has been mainly limited by the lack of manufacturing strategies reliable at industrial level.1,2 Recently, a compressed fluid-based technology, DELOS-SUSP process (Depressurization of an Expanded Liquid Organic Solution-Suspension), has been established for generating “tailor-made” lipid-based nanovesicles. DELOS-SUSP, which comprises the depressurization of a CO2-expanded solution of lipids into an aqueous phase, is a simple, one-pot, versatile and clean manufacturing process, viable at industrial level and able to grant high control over the product properties. A new family of unilamellar nanovesicles, named Quatsomes, has been synthetized by exploiting DELOS-SUSP. More in details, Quatsomes are generated by the spontaneous self-assembly of a quaternary ammonium surfactant and a Cholesterol-like lipid. In general, Quatsomes show a very narrow particle size distribution (PDI 0.15-0.2) and an outstanding homogeneity in terms of morphology. The small size of these nanovesicles (70-100 nm) coupled with the high value of zeta;-potential (+70-80 mV) grants an excellent long-term colloidal stability.3,4 Recently, it has been observed, that those nanovesicles have “built-in” anti-microbial and anti-biofilm activity.5 Furthermore, the inherent structure of such nanovesicles shows the advantage of offering multiple “strategies” for loading bio-actives. Dyes and biomolecules have been incorporated in Quatsomes by exploiting their surface, the hydrophobic environment offered by their membrane, their aqueous inner core and the functional groups available on their surface. Virtually infinite and controlled structures can be generated tuning the experimental parameters and using the generated nanovesicles as “building blocks” of multifunctional bio-active nanodevices. The favorable properties-by-process of Quatsomes together with the inherent advantages of DELOS-SUSP encourage us to further develop and evaluate this versatile “nanomaterial platform” as potential drug delivery carriers.
1. J. Shi et al., Nano Lett., 2010, 10 (9), 3223-3230.
2. H.I C.hang and M.K. Yeh, Int. J. Nanomedicine 2012, 7, 49-60.
3. L. Ferrer et al., Langmuir, 2013, 29 (22), 6519-6528.
4. I. Cabrera et al., Nano Lett., 2013, 13 (8), 3766-3774.
5. N. Thomas et al., J. Mater. Chem. B, 2015, 3, 2770-2777.
9:45 AM - *M1.03
Synthesis and Applications of Nanostructured Biomaterials and Biosystems
Jackie Y. Ying 1
1Institute of Bioengineering and Nanotechnology The Nanos SingaporeShow Abstract
Nanostructured materials are of interest for a variety of applications. This talk describes the design and functionalization of nanostructured materials for biological and biomedical applications. Specifically, we have synthesized metallic, metal oxide, semiconducting and organic nanoparticles and nanocomposites for bioimaging, bioseparation, biosensing, theranostic, drug delivery and tissue engineering applications. The synthesis, unique properties and biocompatibility of these nanostructured biomaterials will be presented in this lecture.
We have also fabricated nanofluidic systems for drug screening, in vitro toxicology, clinical sample preparation and diagnostic applications. The principles behind the design and creation of nanoscale patterns, building blocks and surface functionality to tackle various challenges in biomedical applications will be discussed.
10:15 AM - M1.04
Synthesis of Gold Nanoparticles Specific to Ph- and Salt- Tolerance for Biomedical Applications
Prem C. Pandey 1 Govind Pandey 2
1Indian Institute of Technology(BHU) Varanasi India2BRD Medical College, Gorakhpur Gorakhpur IndiaShow Abstract
The synthesis of gold nanoparticles (AuNPs) having better dispersibility and catalytic ability in variable buffering systems containing desired salt concentrations is reported herein. The fact that aldehydes and ketones results in the formation of catalytic hybrid material with amino functionalized silanes directed the use of carbonyl functional group (aldehydes and ketones) specifically formaldehyde, acetaldehyde, acetone and t-butyl methyl ketone alongwith 3-aminopropyltrimethoxysilane (3-APTMS) to synthesis such nanomaterial. Accordingly, a comparative study on the synthesis of 3-APTMS and variable organic reducing agents mediated synthesis of AuNPs are reported herein. The findings reveal that 3-APTMS capped gold ions are converted into AuNPs with precise control of pH- and salt- sensitivity. The major findings reveal the following: (1) 3-APTMS being amphiphilic, dispersibility of as prepared AuNPs largely depends on the organic reducing agents. (2) An increase in the hydrocarbon content of the reducing agent facilitate the dispersibility of AuNPs in organic solvent whereas decrease of the same increases the dispersibility in water, (3) AuNPs made through aldehydic reducing agents (formaldehyde and acetaldehyde) have relatively better salt and pH tolerance as compared to ketonic reducing agents (acetone, t-butyl methyl ketone), and (4) an increase in 3-APTMS concentrations imparts better salt- and pH- resistant property to AuNPs irrespective of organic reducing agents. A typical example on the role of AuNPs in homogeneous catalysis and as peroxidase mimetic will be discussed.
10:30 AM - *M1.05
Nanoscale Structure and Properties of Biomaterials
Federico Rosei 1
1INRS Varennes CanadaShow Abstract
Modifying the nanostructure/chemistry of materials allows to optimize their properties . Our strategy rests on creating nanopatterns that act as surface cues [2,3], affecting cell behavior. Chemical oxidation creates unique topographies , becoming a general strategy to improve biocompatibility. Our treatment selectively inhibits fibroblast growth while promoting osteogenic cell activity  in vitro. Enhancement of mechano-biocompatibility may occur by coating with spider silk [6,7]. Improvement of antibacterial properties using plasma strategies will also be discussed [8,9].
F Rosei, J Phys Cond Matt 16, 1373 (2004)
F Variola et al, Small 5, 996 (2009)
F Variola et al, Biomaterials 29, 1285 (2008)
F Vetrone et al, Nanolett 9, 659 (2009)
L Richert et al, Adv Mater 20, 1488 (2008)
C Brown et al, Nanoscale 3, 3805 (2011)
C Brown et al, ACS Nano 6, 1961 (2012)
O Seddiki et al, Appl Surf Sci 308, 275 (2014)
 M Cloutier et al, Diam. Rel. Mater. 48, 65 (2014)
11:30 AM - *M1.06
Direct Fabrication of Nitrogen-doped Graphene and Their Hybrid Inks via Submerged Liquid Plasma(SLP) and Electrochemical Exfoliation(ECE) Methods under Ambient Conditions
Masahiro Yoshimura 1
1National Cheng Kung Univ Kanagawa JapanShow Abstract
Nano-carbons have greatly been interested in various fields of research including biomedical area. We believe that the large scale synthesis of nano-carbon should be free from using excess energies for firing, sintering, melting,expensive equipments and/or multple steps. We, propose here Soft processing(=Eco-Processing) of functionalized Graphenes at ambient conditions. The Soft processing provides number of advantages which includes (a) simple reaction set up,(b) at ambient temperature and presure conditions, (c) simple ad short-cut procedures and (d)less operating costs.
In the present study, we have utilized “Submerged Liquid Plasma [SLP]” and “Electrocemical Exfoliation[ECE] methods. SLP methods resulted the direct synthesis of Nitrogen functionalized Graphene Nano-sheets from Graphene suspension and/or Graphite electrode in acetonitrile liquids. Products contains few layers (< 5) Graphene nanosheets. Unsaturated or high energy functional group (e.g. C#65309;C, C#65309;N and Cequiv;N) have formed in the products. We could confirm those functionalized Graphenes are electrochemically active. Using pencil rods instead of Graphite rods we have also succeeded to prepare the Nano-clay/Graphene hybrids by this SLP methods. Reduction and functionalization of Graphene oxides and Synthesis of Graphene/Au Hybrids also realized by SLP.
In the ECE, graphite anode is exfoliated electrochemically by H2O2-NaOH or Glycine-H2SO4 aqueous solutions under ambient temperature and pressure,for 5-30 min with +1-+5 volt, into 3-6 layers Graphene Nanosheets[GNs]. Those conditions are much milder than those reported before using other chemicals like ionic liquids and/or H2SO4-KMnO4,etc.,because O22- ions or ionic complex like Glycine-HSO4- would assist the exfoliation of graphite layers. Our products:GNs suspended in solutions can be transformed in the 2nd step in the same container using BrCH2CN/dioxane into N-FG, further into Au-Hybridized N-FG by the sonification with Au nanoparticles. We have confirmed the excellent catalytic performance of those hybrids. It should be noted that Soft Processing can directly produce “Graphene Ink”;Graphenes dispersed in various liquids, under mild conditions..
Key words: Graphene, Solution,Liquid Plasma, Exfoliation,Hybrid
References J. Mater Chem A,(2014) 2, 3332: Sci. Rep., 4(2014),04395: Carbon,78 (2014),446: Sci. Rep. 4 ,4237-4242 (2014): Nanoscale(2014) 6,12758: Adv. Funct. Mater. 25,298-305(2015): J. Mater Chem A,3,3035(2015)
12:00 PM - *M1.07
Surface Functionalized Magnetite Nanoparticles: Novel Diagnostic Assays and Imaging Using Magnetic Relaxation Dynamics
Kannan M. Krishnan 1 Sonu Gandhi 1 Hamed Arami 1 Amit P Khandhar 2
1University of Washington, Seattle Seattle United States2LodeSpin Labs Seattle United StatesShow Abstract
The Néel relaxation of magnetic nanoparticles (MNP), subject to alternating magnetic fields, depends exponentially on their core diameter whilst the Brownian relaxation depends critically on their hydrodynamic volume. Recent developments in the synthesis of highly monodisperse and phase-pure magnetite nanoparticles allows for reproducible control of the former, even in biological environments, enabling novel imaging, and spectroscopy, under ac excitations such as magnetic particle imaging/spectroscopy (MPI/MPS). With appropriate functionalization of the monodisperse core, and utilizing the latter relaxation, it also allows for the development of sensitive, relaxation based assays.
Following a brief review of the physics of magnetic relaxation, we describe the development of a high-throughput, sensitive and rapid method for detection of proteases, crucial in diagnostics and therapeutic applications, using a facile magnetic assay based on magnetic particle spectroscopy (MPS). We used a peptide labeled with biotin at N- and C- terminals, with a middle part containing a selective site to be recognized and cleaved by a specific protease. When this peptide is added to the neutravidin functionalized nanoparticles the MNPs aggregate, resulting in well-defined changes of the MPS signal (both peak intensity and position - in principle, eliminating false positives). However, in the presence of protease, this peptide is cleaved and as a result, nanoparticles get redispersed in the solution again, and the MPS signal(s) returns to its pre-aggregation state (before addition of the peptide). These variations help to detect a specific protease by MPS, only relying on the magnetic relaxation characteristics of the nanoparticles. The utility of this assay is demonstrated by the detection of two proteases -- Trypsin and Matrix Metalloproteinase.
Further, surface functionalization of the nanoparticles with PEG of appropriate length and density results in favorable biodistribution, avoiding the kidney (of critical concern in patients with chronic kidney disease) and promoting enhanced circulation time in animal models. The latter has demonstrated the first blood volume images in rodents using magnetic particle imaging. Finally, conjugation of dyes turns these MNPs into multimodal contrast agents (MRI, MPI and NIRF) and which we have used to further enhance studies of the MNP biodistribution, with significant anatomical detail, in rodent models.
 Kannan M. Krishnan, IEEE Trans. Mag.46, 2523-2558 (2010
 R. Hufschmid et al, Nanoscale (accepted, in press), DOI: 10.1039/C5NR01651G
 B. Gleich & J. Weizenecker, Nature435, 1214 (2005).
 R.M. Ferguson et al, IEEE Trans. Med. Imag. 34, 1077 (2015)
 S. A. Shah et al, Phys. Rev. B (submitted)
 P. Goodwill et al, Proc. 5th IWMPI (2015)
 Hamed Arami et al, Biomaterials52, 251 (2015)
 This work was supported by NIH/NIBIB grants 1RO1EB013689-01, 1R41EB013520-01 & 2R42EB013520-02A1
12:30 PM - *M1.08
Antibiofouling Neural Electrodes by RF-Plasma Nanotexturing
Sungho Jin 1 Calvin Gardner 1
1Univ of California, San Diego La Jolla United StatesShow Abstract
RF plasma nanotexturing technique is utilized to create dense, vertically aligned metallic nanowire arrays on metallic substrate structures such as coronary stents and neural electrodes. Antibiofouling neural electrodes were produced from a 316L stainless steel substrate by nanotexturing the surface with repetitive RF-plasmas processing and selectively coating the tips of the resultant nanopillars through oblique incidence sputter deposition of hydrophobic PTFE. Such a nanowire array structure induces a significant reduction of surface impedance, thus allowing a room to add antibiofouling nano-island arrays without sacrificing the desired electrical conductivity much. Human aortic endothelial cells were cultured on the antibiofouling electrode surface and cell viability was examined by immunofluorescent imaging of cytoskeletal actin, FDA assay, MTT assay, and area-based evaluations of cell spreading. Data indicates notable antibiofouling properties for the nanotextured surface which is enhanced by the selective addition of a hydrophobic coating. The textured and coated samples exhibited an 8-fold decrease in cell adhesion/coverage, thus enhancing the antibiofouling tendency. The proposed nano processing can be beneficial to chronic electrode implants for the purpose of retaining electrical conductivity while decreasing cellular biofouling.
Suwan Jayasinghe, University College London
Mallika Kamarajugadda, Medtronic, Inc.
Roger Narayan, University of North Carolina at Chapel Hill and North Carolina State University
Antoni Tomsia, Lawrence Berkeley National Laboratory
Symposium Support Applied Physics Reviews|AIP Publishing
M5: Advanced Technologies for Medical and Dental Applications
Tuesday PM, December 01, 2015
Sheraton, 2nd Floor, Liberty B/C
2:30 AM - *M5.01
Printing Living Tissues
Jennifer A. Lewis 1 2
1Harvard University Cambridge United States2Wyss Institute for Biologically Inspired Engineering Cambridge United StatesShow Abstract
The ability to pattern biomaterials in planar and three-dimensional forms is of critical importance for several applications, including drug safety screening, tissue engineering and repair. 3D printing enables one to rapidly design and fabricate soft materials in arbitrary patterns without the need for expensive tooling, dies, or lithographic masks. In this talk, our efforts to creating vascularized living tissues via 3D bioprinting will be described. I will present recent advances in the design of cell-laden inks, extracellular matrices and fugitive (vascular) inks for 3D bioprinting of vascularized, heterogeneous cell-laden tissue constructs with as well as ongoing efforts to characterize these 3D living tissues.
3:00 AM - *M5.02
Tailored Multi-Fluorescent Silica Nanoparticles for In Vitro Studies at Single-Cell-Level
Kurosch Rezwan 1 Laura Treccani 1 Shakiba Shahabi 1
1Univ of Bremen Bremen GermanyShow Abstract
Fluorescently labeled nanoparticles (NPs) are emerging as a versatile tool in biomedical applications and nanotoxicological studies. At present, the simultaneous colocalization of accumulated fluorescent NPs within cellular components is still a challenge due to spectral overlay of NP-fluorescence and multiple fluorescent stained cellular components. To tackle this problem we have developed different synthesis routes to create multi-fluorescent silica NPs with controllable sizes, low polydispersity index, high labeling efficiency and enhanced fluorescence photostability.
By using a water in oil microemulsion method or amino acid catalyzed seeds regrowth technique (ACSRT), core/shell NPs with multiple fluorescence characteristics have been obtaining by direct incorporation of organic fluorescent dyes. Such particles can be easily colocalized and clearly distinguished from multiple stained cellular components using conventional fluorescent microscopes, and offer several advantages for in vitro studies at single-cell-level.
Besides particle size, surface charge plays an important role in cellular accumulation and possible cytotoxicity of NPs. Therefore, we synthesized five different single- or multi-functionalized fluorescent silica NPs (FFSNPs) by introducing various ratios of amino and sulfonate groups into their surface and to tailor particles zeta potential from positive to negative values. We show that particle uptake does not only depend on the surface charge, but also by the presence of serum proteins. In the absence of serum, positively charged NPs are stronger accumulated by cells than negatively charged NPs. In contrast, in serum-containing medium anionic FFSNPs are internalized by cells more strongly. This shows that at physiological condition, when the presence of proteins is inevitable, sulfonate-functionalized silica NPs are feasible choice to achieve a desired high rate of NP internalization.
In conclusion, we show that by creating multiple-doped fluorescent NPs and by tuning surface chemistries, it is possible to design particles with unique properties with high potential as probes for fundamental biological studies as well as for molecular imaging.
3:30 AM - *M5.03
Effects of Graphene and Graphene Oxide Coatings on Stem Cell Growth and Differentiation
Chwee Teck Lim 1
1National University of Singapore Singapore SingaporeShow Abstract
While there have been significant advances in stem cell therapy and tissue engineering, the search for an ideal substrate for stem cell culture and differentiation continues. Human bone marrow derived mesenchymal stem cells (hMSCs) have been widely recognized to have significant biological and clinical importance due to their ability to differentiate into multiple cell types. While stem cell differentiation depends largely on the various soluble factors and biomolecules, lineage commitment of stem cells can also be governed by their interaction with nanoscale features of the extracellular matrix (ECM). Nanotechnology has emerged as a promising tool to design and create materials with nano-sized features and architectures which are capable of biomimicking the native ECM environment for stem cell culture and differentiation. In particular, graphene anf graphene oxide have generated great interest because of its unique chemical, mechanical and electrical properties. The synergy of the properties of graphene and graphene oxide and differentiation potential of stem cells could provide exciting opportunities for new and novel therapeutic applications. However, little is known about the effect of these graphene coatings on stem cell fate. Here, we report the interaction between stem cells and graphene and graphene oxide coating in terms of stem cell growth and differentiation. Our results show that these coatings promoted differentiation of MSCs and their unique differentiation profiles are dependent on the π- π interactions between the graphene/graphene oxide coatings and the soluble biomolecules involved during the differentiation process.
4:30 AM - *M5.04
Engineering 3D Microenvironments on the Nano- and Micro-Scales for Regeneration
Peter X. Ma 1
1Univ of Michigan Ann Arbor United StatesShow Abstract
Regenerative medicine aims to regenerate tissues and organs by utilizing the highly regenerative potentials of various stem cells, such as embryonic stem cells, multipotent adult stem cells, tissue specific stem cells, and induced pluripotent stem cells. There is a growing recognition of 3D matrix microenvironments on the fate and function of stem cells. A key challenge facing regenerative medicine is to rationally design and create 3D microenvironments that can recapitulate those in a developmental or healing program to maintain stemness, to accelerate proliferation, or to direct stem cells to differentiate along a specific therapeutic lineage. Our lab takes a biomimetic approach to design biomaterial-based 3D microenvironments on the nano- and micro-scales (matrix, signals, and supporting cells etc.) for stem cells to regenerate tissues. Several examples of regenerating dental/craniofacial, orthopaedic, and cardiofascular tissues will be presented to demenstrate the effectiveness of biomimetic approaches on the nano- and micro-scales.
5:00 AM - *M5.05
Remineralization Strategies towards Novel Dental Health Care
Mehmet Sarikaya 1 Hanson Fong 1 Deniz Yucesoy 1 Candan Tamerler 2 Greg Huang 1 Sami Dogan 1
1Univ of Washington Seattle United States2University of Kansas Lawrence United StatesShow Abstract
Tooth caries are among the most prevalent of human chronic diseases. Incipient caries, e.g., are the earliest detectable signs of tooth decay clinically and radiographically. At this stage, the lesion has not penetrated the dentin, limited to enamel tissue with an intact DEJ (dentin-enamel junction). If left untreated, caries often result in pulp damage requiring pulp extirpation, complex restorative procedures or tooth extraction. A long-standing practical challenge associated with caries and other dental diseases, therefore, is associated with incorporating a functional mineral layer fully integrated into the molecular structure of the tooth for use in repairing damaged tooth surfaces. Both in teeth and bone, hydroxyapatite (HAp) is the primary mineral component which possess microstructures resulting in distinct mechanical properties relevant for the functional performance of the specific mineralized tissue (enamel, dentin, cementum and bone). Formation and morphogenesis of HAp in dental tissues and bones are controlled by proteins specific to each tissue. Herein, using directed evolution approaches, we identified peptide domains that bind to HAp and showed that they can control formation and morphogenesis of the apatite crystals. Using knowledge-based bioinformatics, and based on a critical discovery that HABPs have sequence similarity to amelogenin (the key protein in enamel formation), we identified amelogenin derived peptides (ADPs). Using ADPS in various solutions and gel formulations, we demonstrated that they can direct calcium phosphate min formation with controlled structural characteristics deposited as a thin mineral layer on dentin, enamel and cementum on extracted human teeth in vitro and rat in vivo. Integrating the recent advances in peptide design for directing biomineralization we address one of the key problems in dental tissue restoration through achieving remineralization on the surface of demineralized teeth. Establishing the scientific foundations for remineralization on teeth and developing novel biomimetic therapies have enormous potential to empower clinicians and practicing dentists to address a wide variety of dental problems and, thereby, disruptively change the current “drill-and-fill,” dental practices
5:30 AM - M5.06
Multi-Layered Modification on Endotracheal Tubes to Reduce Respiratory Complications
Matthew Kuc 1 Fanni Torok 1 Gregory Brotske 1 Ashley Banks 1 Daniel Donahue 1 Ta Hou 1 Heather Lapp 1 Michael Bouchard 1 Zheng Zhang 1
1Teleflex Medical Cambridge United StatesShow Abstract
Endotracheal tubes (ETTs) are a widely used medical device for patients in need of assisted breathing. While in use, biofilm formation occurs as a result of mucus accumulation on the surface of the device which can lead to obstruction of airflow and respiratory infection. In addition, the recent emerging of antibiotic-resistant bacterium further elevates the danger. Therefore, there is a need to modify existing medical devices with alternative therapeutic agents and surface chemistries in order to prevent biofilm formation from bacterium.
In this study, endotracheal tubes were modified by applying a multi-layered, polymer coating to yield anti-microbial and anti-fouling properties. The coating system was composed of three distinctive layers: (1) a reservoir layer composed of an anti-microbial peptide (AMP) for drug release with efficacy for 72 hr to kill bacteria above the minimum inhibitory concentration (MIC). 2) A capping layer, which controls release rate of AMP during the time scale and provide anchorage for 3) a non-fouling hydrogel layer, which accommodates AMP on the surface and provide sputum resistance.
Two different polymers were designed and synthesized based on their functions. A variety of analytical and in vitro methods were carried out to assess the dual functionality of the modified ETTs. AMP release was quantified using high-performance liquid chromatography (HPLC) and resulted in a controlled release pattern after 72 hr. The anti-fouling coating was able to reduce mucus attachment by 25-30% determined by radio-labeled porcrine mucin. In vitro cultures of S. aureus (MRSA) and P. aeruginosa were used to assess the efficacy of the AMP. The AMP was able to maintain a 3.5-3.7 log reduction against MRSA for 72 hr. A decrease in efficacy was observed in P. aeruginosa cultures. These results show great promise for manufacturing medical devices capable of greatly reducing respiratory complications.
5:45 AM - M5.07
Biomimetic Processing to Mimic Bonersquo;s Nano- and Micro-Structural Organization
Brian Wingender 1 Patrick Bradley 2 Jeff Ruberti 2 Laurie Gower 1
1UF MSamp;E Gainesville United States2NEU Boston United StatesShow Abstract
We propose that the next generation of bone substitutes could be load-bearing if they are engineered as a bioactive material which not only emulates the complex hierarchical organization of the interpenetrating protein and mineral phases, but is also capable of maintaining the mechanical properties throughout bioresorption. The polymer-induced liquid-precursor (PILP) process has been previously shown to result in the intrafibrillar mineralization of different types of type I collagen substrates, which has reproduced the fundamental nanostructural organization of native mineralized tissues. In order to achieve bone-like mechanical properties, we are now targeting the lamellar microstructure of bone by preparing laminated films of dense, collagen scaffolds that are assembled with cholesteric order. These liquid-crystalline (LC) collagen scaffolds are made by concentrating acidic collagen solutions up to physiological levels, and then stabilizing the assembly through fibrillogenesis brought on by neutralization. We are currently mineralizing these dense, LC collagen constructs via the PILP process to create a bioresorbable material with a high degree of mineral loading, mimicking bone&’s hierarchical organization from the nanoscale to the microscale. It is hypothesized that this biomimetic material will enable us to emulate the high strength and toughness of bone, while also providing a bone-like matrix that can stimulate cellular activity to regenerate natural bone tissue through the concerted action of the bone remodeling unit.
M4: Advanced Technologies for Biomedical Applications
Tuesday AM, December 01, 2015
Sheraton, 2nd Floor, Liberty B/C
9:00 AM - *M4.01
Processing of Bioactive Glass with Nanostructure Optimized for Biomedical Applications
Ukrit Thamma 1 Roman Golovchak 2 Tia J. Kowal 1 Matthias M. Falk 1 Himanshu Jain 1
1Lehigh Univ Bethlehem United States2Austin Peay State University Clarksville United StatesShow Abstract
Often glass, which is made traditionally by quenching a melt, is considered a homogeneous solid for many applications. This has been true certainly in the biomedical field, where, for example, the most widely used 45S5 sodium phosphosilicate glass is assumed to be a single phase bioactive material. However, now we are learning that it is not only phase separated at nanoscale but in fact cell response is significantly affected by the nature of its nanostructure. We have also discovered that more than ten thousand times larger cells respond differently on nano-macro porous calcium silicate bioactive scaffolds that differ only in the size of nanopores, for example, 4 nm vs. 18 nm. These observations demonstrate the importance of nanostructure for the performance of glass products in dental and bone regeneration applications. Then it becomes crucial to develop glass fabrication processes for a given chemical composition, which will yield desired nanostructure of the ultimate product. In this presentation we will review and discuss these specific processes, which are broadly based on the conventional melt-quench and sol-gel methods of glass making. We will show how the variables like melt temperature, cooling rate, sample size of the former method affect the nanostructure (for example, interconnected vs. droplet-type distribution of phases), or gelation time, type/amount of catalyst, drying conditions, sample configuration, etc. affect the nano/macro porosity that results from the latter process. Examples of the correlation between processing conditions with the nanostructure and the performance of the final product (such as attachment and proliferation of MC3T3-E1 pre-osteoblast cells) will be presented.
9:30 AM - M4.02
Multiscale Patterning of Metallic Glasses through Sacrificial Zinc Oxide Templates for Biologically Functional Surfaces
Jonathan Phillip Singer 1 2 Jagannath Padmanabhan 2 Candice Pelligra 2 Youngwoo Choo 2 Jittisa Ketkaew 2 Themis Kyriakides 2 Jan Schroers 2 Chinedum Osuji 2
1Rutgers University Piscataway United States2Yale University New Haven United StatesShow Abstract
Bulk metallic glasses (BMGs) have been advanced as a means to achieve durable multiscale, nanotextured surfaces with desirable properties dictated by topography for a multitude of applications, including cellular response-manipulating patterns. One barrier to this is the lack of a bridging technique between macroscale thermoplastic forming processes and nanoimprint lithography. This arises from the difficulty and cost of generating controlled nanostructures on complex geometries by conventional top-down approaches, compounded by the necessary destruction of any resulting reentrant structures (such as any feature patterned on a vertical wall) during rigid demolding. We have developed a generalized method to overcome this limitation by sacrificial template imprinting using zinc oxide nanostructures. It is established that such structures can be grown cheaply and quickly with tunable morphologies on a wide variety of substrates out of solution, which we exploit to generate the nanoscale portion of the multiscale pattern through this bottom-up approach. In this way, we achieve metallic structures simultaneously demonstrating features from the macroscale down to the nanoscale requiring only the top-down fabrication of macro/microstructured molds. Upon detachment of the formed part from the multiscale molds, the zinc oxide remains embedded in the surface and can be removed by etching in mild conditions to both regenerate the mold and render the surface of the BMG nanoporous. Further, by skipping the etching step on the BMG, we have generated surface nanocomposites of antimicrobial nanorod arrays embedded in a metallic glass. The ability to pattern metallic surfaces in a single step on length scales from cm down to nm is a critical step towards fabricating devices with complex shapes which rely on multiscale topography for their function, such as medical implants or antimicrobial components.
9:45 AM - *M4.03
Electrochemical Deposition of Materials for Biomedical Applications
Igor Zhitomirsky 1
1McMaster Univ Hamilton CanadaShow Abstract
Electrophoretic deposition method has been developed for the deposition of biopolymers, such as chitosan, hyaluronic acid, alginic acid and chiral polymers, such as poly-l-lysine and polyl-ornithine. The electrodeposition mechanism is triggered by the pH changes at the cathode or anode surface. It was found that polymers can be used as dispersing, charging and film forming agents for electrophoretic deposition of nanostructured hydroxyapatite, titania, zirconia and other bioceramics, halloysite nanotubes and bioglass. The composite films containing bioceramics and bioglass nanoparticles in a polymer matrix were prepared on stainless steel, Ti and NiTi alloy substrates. The films provided corrosion protection of the metallic implants in simulated body fluid solutions. The results of thermogravimetric analysis showed that hydroxyapatite content in the polymer matrix was varied in the range of 35-80 wt% by variation of hydroxyapatite or polymer concentration in the solutions. The hydroxyapatite particles showed preferred crystallographic orientation in the chitosan matrix. It was shown that film thickness can be varied in the range of 0.1-200 microns. The composite films were prepared as monolayers, multilayers or materials of graded composition. Electrochemical strategies have been developed for the deposition of composite films containing heparin and albumin in a biopolymer matrix. It was found that composite films can be used for controlled release of drugs and antimicrobial agents. The co-deposition of biopolymers, enzymes and carbon nanotubes alowed for the fabrication of composite films for application in biosensors. It was discovered that bile acids can be used for efficient dispersion and electrophoretic deposition of carbon nanotubes for application in biosensors. New electrochemical strategies have been developed for the anodic electropolymerization of polypyrrole and fabrication of adherent films on stainless steel. The approach was based on the use of dopants from dopamine and salicylic acid families, which reduced electropolymerization potential, promoted charge transfer and allowed for the fabrication of adherent films of polypyrrole and composites. The films showed promising performance for aplications in biomedical implants and biosensors.
10:15 AM - M4.04
Conformal Piezoelectric Systems for Clinical and Experimental Characterization of Soft Tissue Biomechanics
Canan Dagdeviren 1 John A. Rogers 2
1Massachusetts Institute of Technology Cambridge United States2University of Illinois at Urbana, Champaign Urbana United StatesShow Abstract
Mechanical assessment of soft biological tissues and organs has broad relevance in clinical diagnosis and treatment of disease. However, at present it relies on characterization methods that are invasive, lack micro-scale spatial resolution, and are only tailored for specific regions of the body under quasi-static conditions. Here, we develop conformal and piezoelectric nanoribbons of lead zirconate titanate (PZT) that enable in vivo measurements of soft tissue viscoelasticity in the near surface regions of the epidermis. Soft, reversible lamination onto the skin enables rapid, quantitative assessment of viscoelastic moduli, with ability for spatial mapping. These systems achieve conformal contact with the underlying complex topography and texture of the targeted skin, as well as other organ surfaces, under both quasi-static and dynamic conditions. Experimental and theoretical characterization of the responses of piezoelectric actuator-sensor pairs laminated on a variety of soft biological tissues and organ systems in animal models provides information on the operation of the devices. Studies on human subjects establish the clinical significance of these devices for rapid and non-invasive characterization of skin material properties. Applications in vitro with mock and ex vivo skin preparations under varying conditions and in vivo on human subjects, collected at various locations over all main regions of body, under both normal conditions and following administration of pharmacological and cosmetic (moisturizing) agents, demonstrate the capabilities.
10:30 AM - M4.05
Direct Laser Writing of Cell Traps and Guides on Anatase and Graphite Coatings on Si
Yuchen Xiang 1 Rosa Martinez 1 Fernando Agullo-Rueda 2 Josefa Predestinacion Garcia Ruiz 1 Vicente Torres Costa 1 Miguel Manso-Silvan 1
1UAM Madrid Spain2ICMM-CSIC Madrid SpainShow Abstract
Cell guides and cell traps consist of microstructured surfaces featuring selective cell affinity within calibrated designs. Among the bunch of techniques being used for their fabrication, direct laser writing emerges as a reliable, fast and flexible technique. In the present work, an IR laser has been used to selectively write anatase and graphite coatings on Si. The laser parameters were optimized to induce local damage with features of circa 10 mu;m and minimized ablation searching for the sharper edges possible. The writen features were characterized by both microscopic and spectroscopic techniques. Field emission scanning electron microscopy shows that hierarchichal structures are formed at particular processing conditions with nanofiber decorated microparticles emerging from irradiated rails. Energy disperse X-ray maps show that the underlying Si becomes the dominant element in the irradiated areas. Thus, the micropatterns can be described as hybrid chemo-topographic structures. This feature is additionaly confirmed by micro-Raman spectroscopy. The variation of the surface properties was further tested by making contact angle measurements on densely irradiated surfaces. The relatively hydrophobic behaviour of the anatase and graphite films became a strongly hydrophilic surface after irradiation. Particular micropatterns were designed for the culture of human mesenchymal stem cells (hMSCs). Adhesion studies confirmed that the irradiated rails become barriers for the hMSCs, which presented particularly eleongated shapes on confluent edges with the micropatterned features. Particular designs with non confluent hexagonal corrals show that cells can migrate around the hexagons while they become mostly trapped within the corrals. Such devices are relevant tools for the study of hMSCs differentiation under non-conventional substrate conditions.
10:45 AM - M4.06
Development of SU8-Based Nanocomposite Materials for Biomedical Applications
Marijana Mionic Ebersold 1 Heinrich Hofmann 1
1Ecole Polytechnique Feacute;deacute;rale de Lausanne (EPFL) Lausanne SwitzerlandShow Abstract
The need for new even smarter microengineering materials for biomedical applications is driven by a need for enhancement of their performance in real biomedical applications. Therefore, we developed new advanced nanocomposite materials based on biocompatible SU8 resist (standard negative tone photoresist). In order to control and engineer the properties of the nanocomposite materials, we used different fillers like carbon nanotubes (CNTs) previously optimized for this purpose, carbon black nanoparticles or TiO2.
At first, we have optimized the inks preparation conditions (including the appropriate solvents, surfactants and all steps of the nanoparticle-based inks preparation process). Nanoparticles dispersion was characterized in the ink and in the SU8 matrix in composites. Processing of the obtained composites was successfully optimized for the ink jet printing process, photolithography and screen printing on various substrates (like different wafers, plastic, paper, fabric). Especially, photo-patterning was optimized at each processing step in order to minimize their drawbacks. In this way, we achieved to develop new biocompatible nanocomposites having high absorption (SU8-carbon black nanocomposites), high refraction (SU8-TiO2 composites), tuneable electrical resistivity, thermal conductivity and mechanical properties (SU8-CNTs nanocomposites). As an example, the increase in hardness of 122% and in the Young&’s modulus of 56% (for 0.8 wt% of CNTs in SU8) and thermal conductivity of 3.7 times (for 10wt% of CNTs in SU8) was achieved for smart nanocomposites containing randomly oriented CNTs.
11:30 AM - M4.07
Effect of Heat Treatment on the Microstructure, Interface Properties and Corrosion Behavior Of Ti6Al4V via Direct Metal Laser Sintering
Yangzi Xu 1 Yuan Lu 1 Jianyu Liang 1 Richard D Sisson 1
1Worcester Polytechnic Institute Worcester United StatesShow Abstract
Titanium-based alloys are common materials for orthopedic implants. The fast development in additive manufacturing has broadened their applications in biomedical area, because of its high geometrical freedom in fabricating customized implants. Direct Metal Laser Sintering is an additive manufacturing technique. Due to high localized thermal input and fast cooling rate, the as-sintered materials contain non-equilibrium phase. In Ti-6Al-4V, the as-fabricated microstructure is acicular martensite with poor ductility. The major failure mode for Ti-6Al-4V is by fretting corrosion at the metallic interface in body fluid. So, proper post-treatments are introduced to ensure better properties. In this work, a variety of solutions, stress relieving and annealing heat treatments were conducted on Ti-6Al-4V fabricated by direct metal laser sintering. The effect of heat treatment temperature on microstructure, mechanical properties and corrosion behavior were experimentally investigated. The microstructure, phase percentage and lattice parameters were measured by X-ray diffraction with Rietveld refinement. The corrosion behavior of post heat treated samples were characterized electrochemically in simulated body fluid. It was found that β solution treatment, annealing and stress relieving at elevated temperature can improve the corrosion resistance by reducing the α/β phase boundaries which are vulnerable to corrosion. Rutile phase with different degree of crystallinity was detected on the Ti-6Al-4V/electrolyte interface after various heat treatments. X-ray photoelectron spectroscopy (XPS) was utilized to examine the interface properties.
11:45 AM - M4.08
Electroless Plating to Tune the Physiochemical Properties of Nanostructured Silicon Nitride for Use in Device Fabrication
Julie Whelan 1 Nuwan Bandara 1 Buddini Iroshika Karawdeniya 1 Jason Dwyer 1
1University of Rhode Island Kingston United StatesShow Abstract
Silicon nitride is a ubiquitous nanofabrication material that offers favorable mechanical and electrical properties in a multitude of device types. We favor thin-film silicon nitride membranes with well-defined micro- and nanoscale pores to make chemical sensing devices, including single-molecule nanopore sensors. Nanopore sensors pass solution-phase molecules, usually with electrophoretic driving, through ~1-100nm diameter channels in thin, <100nm membranes. Silicon nitride has favorable physical properties for supporting nanopores, but its complex surface chemistry poses challenges for these devices in terms of chemical stability and in the strong interactions between the chemically-diverse surface and highly constrained molecules within the pores. Pore clogging is only one possible challenge we are hoping to circumvent. We use electroless gold plating to controllably tailor the nanopore dimensions, and to allow thiol monolayer self-assembly to give us tunable surface chemistry for improved chemical stability, performance, and reliability. We show control over the thin gold film nanostructure and surface decoration, and can use the extreme nature of the zeptoliter nanopore volume to probe chemical-surface interactions and improve sensing. The deposition of electroless gold films onto silicon nitride opens up a myriad of applications, and can provide a base for electrical connections. Furthermore, this process can be used in combination with spatial patterning of the gold for the fabrication of optically active surfaces, including substrates for surface enhanced Raman spectroscopy.
12:00 PM - M4.09
Structurally Reinforced Biomimetic Self-Assembling Peptide Scaffold by One-Step Electrospinning Procedure
Robabeh Gharaei 1 Giuseppe Tronci 1 2 Parikshit Goswami 1 Robert Phil Davies 2 Stephen Russell 1
1University of Leeds Leeds United Kingdom2University of Leeds Leeds United KingdomShow Abstract
Self-assembling peptides (SAPs) have the ability to spontaneously assemble into hierarchical structures in solutions such as ribbons, fibrils and fibres. The reversible molecular association of SAPs has been shown to macroscopically lead to self-supporting gels, offering great promise in therapeutics e.g. bone and enamel regeneration. Self-assembled gels typically display weak mechanical properties. Although these gels could have been applied as e.g. injectable scaffold in treatment of small size bone/tooth defects, their mechanical stability is insufficient for large load-bearing bones and there are challenges in implanting them into tissue defects. Incorporation of SAPs into polymeric matrices is a common strategy to enhance their mechanical stability; however integrated methods enabling fibre assembly at both micro and molecular levels are lacking. To address the above mentioned challenge, this research investigated the encapsulation of two types of tape forming 11 amino acid residue SAP within a poly(ε-caprolactone) (PCL) fibrous web via. an electrospinning process. With regards to electrostatic charges during spinning process, P11-4 (CH3COQQRFEWEFEQQNH2) with -2 net charge and P11-8 (CH3COQQRFOWOFEQQNH2, where O is ornithine) with +2 net charge were selected as model SAPs. Resulting webs exhibited interesting biphasic nano- and micro-structural features resulting from simultaneous fabrication processes at molecular and microscopic level. The novel mechanism of fabricating electrospun PCL sub-micron fibres containing self assembled peptide nano-fibrils in a simple one-step process is resulting from the SAP monomeric assembly and the spinning process. FTIR and CD spectroscopy results on PCL-peptide solutions suggested that monomeric peptide self-assembly takes place during or immediately after electrospinning, while FTIR spectroscopy highlighted a β-sheet secondary conformation across the fibres. Peptide concentration and its net charge were found to be highly influential in the fibrous morphology and specifically in determining the nano-scale structure of the fabric. The direct and indirect cell culture studies on the electrospun self-assembled matrices demonstrated a spread-like morphology of L929 mouse fibroblasts. The biphasic structure combines the benefits of nano-fibres, suitable for cell attachment and submicron fibres with open pore areas suitable for cell penetration and differentiation .Considering the current challenges of 3D scaffolds such as lack of surface bioactivity or poor biomechanical stabilities, the investigations of these materials for mineralization of hard tissues are underway.
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12:15 PM - M4.10
Tailoring the Geometrical and Structural Features of Carbon Nanotubes for Biomedical Applications
Masoud Golshadi 1 Michael Schrlau 1
1Rochester Inst of Technology Rochester United StatesShow Abstract
Carbon nanotubes (CNTs) have been studied and utilized in a variety of biomedical applications including drug delivery devices, cellular interfacing, biosensors and molecular detection owing to their unique chemical, mechanical, and electrical properties and hollow structure. Template-based chemical vapor deposition (CVD) is one of the most efficient ways of CNT synthesis. The CNTs manufactured by this process are the most versatile for a wide range of applications due to the possibility of integrating them into nanoscale devices without the need for nano-assembly. In this process, decomposition of carbon carrying gas results in deposition of carbon over a choice of template. The template dictates certain physical features of the CNT, including length and outer diameter, while the process itself affects features, such as tube wall thickness, carbon deposition rate and carbon morphology. These CNTs has been used previously for injecting sub-attoliters of fluid and particles into cells and electrically measure cell membrane kinetics. Also, electrochemical sensors have been fabricated by array of aligned CNTs in an integrated chip. In order to properly employ CNTs for aforementioned applications, tailoring the CNT features and properties for any specific application is highly desirable.
To understand how process parameters affect the resultant CNTs manufactured by template-based CVD and to control their geometrical and structural features, the results of a systematic parametric study will be presented. The effect of three main process parameters of deposition time, temperature, and gas flow rate, on properties of CNTs resulted from deposition of carbon over commercially available anodized aluminum oxide membranes will be discussed. The results show that temperature and deposition time can be used for fabricating CNTs with very thick walls and creation of carbon layer for interfacing with CNTs. For changes in precursor gas flow rate, carbon deposition reaches a maximum where mass transport or reaction kinetics limits the deposition below and above that threshold. Moreover, deposition time shows three regimes of nucleation, normal deposition, and carbon infiltration, over the period of 20 hours. Importantly, carbon morphology does not change over the range of the three parameters tested. These findings show that process parameters can be independently utilized to produce CNTs with similar or differing cross-sectional dimensions and other useful features, each with distinct advantages.
The results of the work provide a means of tailoring the properties of free or embedded CNTs that are useful for bio applications including implantable sensors, bio-fluid transport, electrochemical sensing and cellular biology. Preliminary work will be presented to highlight how tailoring CNT properties are useful for these applications.
12:30 PM - M4.11
The Solvents Effect on Molten Gallium by Sonochemistry
Vijay Bhooshan Kumar 1
1Bar Ilan Univ Ramat gan IsraelShow Abstract
Due to the low melting point of gallium (29.8 #730;C), it can be melted in warm water/organic liquids/aqueous organic solution which are not too volatile, and thus produce two immiscible liquid phases. Irradiation of such a liquid system with ultrasonic energy induces cavitation in the liquid, which results in dispersion of the molten gallium as micro/nano-spheres. We attempted to entrap organic substances in metallic Ga particles during their ultrasonic formation, rather than by homogeneous reduction of metal ions in solution. Chiral imprinting in molten Ga can be attained by ultrasonic irradiation of molten Ga overlayed by an aqueous solution of D- or L-tryptophan. The enantiomeric excess (~12%) was determined using polarimetry, Chiral HPLC and CD measurements. When the reaction was done with other low melting point metals (Sn, In, Ga and Zn) under sonication. Binary combinations of bismuth and one of these metals were melted together in hot silicone oil and irradiated with ultrasonic energy to form micro/nano alloy particles. It was found that bismuth forms metal matrix composite with tin and zinc, intermetallic compounds with indium and an alloy with gallium. The extension of this work was studied the combined effect of ultrasonic cavitation and heterogeneous reduction in binary systems that included molten gallium and ionic solutions of one of several metals. It was revealed that in all the cases of the reducible ions, the free metals (Pt, Ag, Cu, and Au) were obtained together with some intermetallic compounds with the gallium (PtGa3, Ag2Ga, CuGa2 and AuGa2). It was found that Ga-Pt embedded in graphene showed better MOR and ORR activity than a commercial Pt/C catalyst. The same process was followed for fabrication of carbon dots (C-dots) doped with Ga atom (Ga@C-dots). Ga@C-dots showing the high photosensitization with respect to that of pristine C-dots. Ga@C-dots was found very high antimicrobial activity.
V. B. Kumar, G. Kimmel, Z. Porat, A. Gedanken, New J. Chem.2015, (Accepted) DOI: 10.1039/C5NJ00781J
V. B. Kumar, Z. Porat, A. Ged