Donglei (Emma) Fan, University of Texas at Austin
Jianping Fu, University of Michigan
Xingyu Jiang, National Center for Nanoscience and Technology
Matthias Lutolf, Ecole Polytechnique Federale de Lausanne
Symposium Support Air Force Office of Scientific Research
National Science Foundation
H3/B3: Joint Session: Biointerfaces
Monday PM, December 01, 2014
Sheraton, 2nd Floor, Grand Ballroom
3:00 AM - *H3.01/B3.01
Hydrogel Microbeads and Microfibers for Biomedical Applications
Shoji Takeuchi 1 2
1The University of Tokyo Tokyo Japan2Japan Science and Technology Agency Tokyo JapanShow Abstract
In this presentation, I am planning to talk about several MEMS/Microfluidic-based approaches for the rapid and reproducible construction of hydrogel microstructure. Hydrogels are attractive materials because of its excellent deformability, biocompatibility, and the ability to be chemically-modified. They are thus very useful for various biomedical applications including implantable monitoring and tissue engineering.
Fluorescent hydrogels hold great promise for in vivo continuous glucose monitoring with wireless transdermal transmission and long-lasting activity. We synthesized a highly-sensitive fluorescent monomer, and then fabricated injectable-sized fluorescent polyacrylamide hydrogel beads and fibers with high uniformity and high throughput. We find that the fluorescent beads provide sufficient intensity to transdermally monitor glucose concentrations in vivo.
Large-scale 3D tissue architectures that mimic microscopic tissue structures in vivo are very important for not only in tissue engineering but also drug development without animal experiments. We demonstrated a construction method of 3D tissue structures by using cell beads and cell fibers. To prepare the cellular beads, we used an axisymmetric flow focusing device (AFFD) that allows us to encapsulate HepG2 cells within monodisperse collagen beads. We then seeded 3T3 cells on the surface of the collagen beads. Finally HepG2 and 3T3 cells were successfully made contact with each other. Moreover, by putting these capsules in a 3D chamber and incubating them, we successfully established complicated and milli-sized 3D structures. We believe that altering the shape can be possible as simple as changing the mold, and will try to combine multiple types of cells to create more complex system that functions as a living organism. As the cell fibers, a cell-encapsulating core-shell hydrogel fiber was produced in a double coaxial laminar flow microfluidic device. When with myocytes, endothelial, and nerve cells, they showed the contractile motion of the myocyte cell fiber, the tube formation of the endothelial cell fibers and the synaptic connections of the nerve cell fiber, respectively. By reeling, weaving and folding the fibers using microfluidic handling, higher-order assembly of fiber-shaped 3D cellular constructs can be performed. Moreover, the fiber encapsulating beta-cells is used for the implantation of diabetic mice, and succeeded in normalizing the blood glucose level.
Yun Jung Heo , Hideaki Shibata , Teru Okitsu , Tetsuro Kawanishi, and Shoji Takeuchi: Long-term in vivo glucose monitoring using fluorescent hydrogel fibers, Proc. Natl. Acad. Sci. USA, vol. 108(33), pp. 13399-13403, 2011
Hideaki Shibata, Yun Jung Heo, Teru Okitsu, Yukiko Matsunaga, Tetsuro Kawanishi, and Shoji Takeuchi: Injectable hydrogel microbeads for fluorescence-based continuous glucose monitoring, Proc. Natl. Acad. Sci. USA, vol. 107, no. 42, pp. 17894-17898, 2010
Hiroaki Onoe, Teru Okitsu, Akane Itou, Midori Kato-Negishi, Riho Gojo, Daisuke Kiriya, Koji Sato, Shigenori Mirua, Shintaroh Iwanaga, Kaori Kuribayashi-Shigetomi, Yukiko Matsunaga, Yuto Shimoyama, and Shoji Takeuchi: Metre-long Cellular Microfibres Exhibiting Tissue Morphologies and Functions, Nature Materials, vol.12, pp. 584-590, 2013
3:30 AM - H3.02/B3.02
Bioactive and Cell-Laden Nanofibrous Scaffolds Fabricated through a One-Step Process
Qilong Zhao 1 Min Wang 1
1The University of Hong Kong Hong Kong Hong KongShow Abstract
Electrospinning is a popular technique for making nanofibrous tissue engineering scaffolds. After cell incorporation, the cell-scaffold construct can be used to regenerate various human body tissues/organs. However, owing to the normally dense structures of electrospun scaffolds, cells can only be seeded in 2D on scaffold surface using the post-electrospinning cell seeding approach. For putting cells in 3D and directly inside electrospun scaffolds, we designed and investigated a facile method by combining cell seeding with scaffold fabrication. In this method, cell electrospraying was performed concurrently with electrospinning of the scaffold, placing cell-encapsulated microspheres into the matrix of nanofibrous scaffold, and the subsequent immersion treatment dissolved the shell of microspheres, releasing the cells for the cell-laden scaffold. In our experiments, a dual-source dual power setup was employed for conducting concurrent cell electrospraying and electrospinning. For cell electrospraying, a coaxial device was used. A cell suspension of human umbilical vein endothelial cells (HUVECs) and a gelatin/alginate blend solution were fed into the inner and outer concentric tubes, respectively. Crosslinked, core-shell structured microspheres containing HUVECs could be dissolved by immersing them in a cell culture medium, releasing the cells. The microsphere structure and cell viability of both encapsulated cells and released cells were studied using SEM, live/dead staining assessment assisted by fluorescent microscopy and laser scanning confocal microscopy. The optimal condition for cell electrospraying was investigated by modulating major processing parameters (composition of polymer blend, applied voltage, flow rate, etc.). For electrospinning, emulsions were made using PLGA solutions and vascular endothelial growth factor (VEGF)-containing PBS (or PBS alone). They were subsequently electrospun to make nanofibrous scaffolds with or without VEGF incorporation. Various experiments were conducted for studying the morphological and structural properties of nanofibrous scaffold, as well as the release behavior of VEGF. When concurrent cell electrospraying and emulsion electrospinning was performed, bioactive and cell-laden scaffolds were fabricated. The post-electrospinning immersion treatment could release encapsulated cells in the nanofibrous scaffolds. Furthermore, the space left by the dissolved microspheres provided the room for subsequent cell proliferation and infiltration. Cell culture experiments and comparative studies were then performed for evaluating cell functions in scaffolds with or without VEGF incorporation. Results indicated that cell proliferation and cell infiltration were enhanced in VEGF-loaded scaffolds. This new fabrication method can lead to breakthroughs in developing electrospun scaffolds for the regeneration of complex human body tissues.
3:45 AM - H3.03/B3.03
Design Complex Hydrogel Microparticles for High Throughput 3D Cell Culture, Co-Culture and Microtissue Production
Yen-Chun Lu 1 Wei Song 1 Duo An 1 Robert Schwartz 2 Minglin Ma 1
1Cornell University Ithaca USA2Weill Medical College of Cornell University NYC USAShow Abstract
Cell encapsulation in hydrogel microparticles have been investigated for decades in various bioengineering applications including tissue engineering, and cell therapy. However, most of the time, the cells are encapsulated randomly in whatever material that forms the microparticles, most commonly alginate. The lack of control over the spatial organizations of the cells and the extracellular environment within the microparticles significantly limits for advanced applications. Here we report a novel, multi-fluidic cell microencapsulation approach where 1 or more types of cells are encapsulated in pre-assigned compartments in the microparticles with controlled extracellular matrix. These microparticles can be produced with controllable and nearly monondispersed sizes at rates of over 10,000 microparticles per min and therefore provide a promising platform for high throughput applications. We demonstrated the utilization of these extracellular matrix-supported microparticles for 3D culturing of cells that typically require specific microenvironment to survive such as human umbilical vein endothelial cells (HUVECs) and small intestine stem cells. By taking advantage of the confinement effect, we also showed robust and scalable productions of size-controlled multicellular microtissues. Lastly, to demonstrate the broad applications of these microparticles, we performed proof-of-concept studies on three different co-culture systems including cell segregations under 3D confined space, the supporting role of stromal cells in hepatocyte functions and the paracrine cell signaling in aggregation of endothelial cells, all in a high throughput manner.
4:30 AM - *H3.04/B3.04
Strategies for Creating Functions in Polymer-Based Materials by Combining Different Components
Andreas Lendlein 2 1
1University of Potsdam Potsdam Germany2Helmholtz-Zentrum Geesthacht Teltow GermanyShow Abstract
A common strategy for the creation of functions in polymeric materials is the targeted combination of different polymers or polymers with inorganic components and the design of the interface between the phases . Hereby the different components can be physically mixed or joined. Alternatively they can be covalently linked.
Several examples for the design of functions are presented, each illustrating a different concept to gain a function. The multivalent binding of polyglycerols on micro porous polyetherimide membranes combines a separation capability with hemocompatibility . The covalent integration of nanoparticles as netpoints in a polymer network matrix enables a magneto sensitive reversible movement of the resulting hybrid material . The pore morphology of polymeric foams strongly influences their shape-memory capability . The internal geometry of a magnetic, active phase in a polymer matrix results in a triple shape effect, whereby the series of the shape changes can be determined by the applied stimulus .
The fundamental principles demonstrated in these material systems might stimulate further research in the field of multifunctional materials.
 M. Behl, M. Razzaq, A. Lendlein, Adv. Mater. 2010, 22, 3388-3410.
 A.T. Neffe, M. von Ruesten-Lange, S. Braune, K. Lützow, T. Roch, K. Richau, A. Krüger, T. Becherer, A.F. Thünemann, F. Jung, R.
Haag, A. Lendlein, J. Mater Chem B, 2014, 2, 3626-3635.
 M.Y. Razzaq, M. Behl, K. Kratz, A. Lendlein, Adv. Mater. 2013, 25, 5730-5733.
 T. Sauter, K. Kratz, A. Lendlein, Macromol. Chem. Phys. 2013, 214 (11), 1184-1188.
 M.Y. Razzaq, M. Behl, K. Kratz, A. Lendlein, Adv. Mater. 2013, 25, 5514-5518.
5:00 AM - H3.05/B3.05
Multifunctional Nerve Guidance Channels for Improved Neural Regeneration and Prosthetic Interfaces
Ryan Koppes 1 2 Xiaoting Jia 1 2 Seongjun Park 3 Christina Tringedes 1 Polina Anikeeva 1 2
1Massachusetts Institute of Technology Charlestown USA2Massachusetts Institute of Technology Cambridge USA3Massachusetts Institute of Technology Cambridge USAShow Abstract
There is currently no effective treatment strategy following traumatic injury to the peripheral nervous system (PNS) in either partial or full loss of extremity function. Recent work has demonstrated neural recording and electrical stimulation devices that allow for neural-motor control of prosthetic limbs. However, much improvement is required to reach the resolution of neural interfacing needed for physiological functionality. In addition to neural interfacing, tissue engineering strategies are potential means to restore functionality after traumatic injury to the PNS. However, current interventions are years from being effective in the clinic. Therefore, our goal is to engineer material platforms that both promote nerve regeneration and provide an electrical interface for prosthetic integration that is clinically relevant now.
To date, the influence of nerve channel geometry and dimensions of sub-200 mu;m scale on neural regeneration has been poorly investigated due to material processing. For interfacing with either the motor or sensory axons of the PNS, geometric constraints may provide a means for selectively regenerating axons to intimately interface electrodes with sensory or motor nerve fibers, respectively. Furthermore, topography robustly influences the orientation and length of neural growth. However, no technique currently exists to fabricate mu;m topography features on the interior surface of nerve guidance channels without the inclusion of films or rolling.
Herein, we present a new method for engineering polymeric nerve guidance channels with intrinsic topography or recording electrodes. Utilizing a thermal drawing process (TDP), macro-scale preforms of biocompatible polyetherimide were made with rectangular and cylindrical channels. Topographical features or electrodes composed of conductive polyethylene were machined and added to the preforms. TDP reduced the cross-sectional dimensions by up to 200 times while maintaining the original geometries. Rectangular, rectangular with microgrooves, and cyclindrical neural growth channels with dimensions 30-200 mu;m were evaluated in vitro for their influence on neurite outgrowth from primary dorsal root ganglia (DRGs). Total distance of neurite outgrowth into the channel as well as the orientation of neurite extension and cell nuclei within the channel were measured with respect to the geometry and dimensions of the growth channel. Preliminary data suggests that narrower channels (40-60 mu;m) enhance the orientation of DRG outgrowth compared to larger channels (>100 mu;m), but very limited growth is observed in small channels (<40 mu;m). However, inclusion of microgrooves within the large channel increases neurite orientation. These results demonstrate our ability to utilize the TDP to design new polymeric nerve guidance channels as a strategy for PNS regeneration and neural interfacing.
5:30 AM - H3.07/B3.07
How Architecturally and Functionally Complex Polymers Can Optimize Therapeutic Proteins In Vivo
Mi Liu 1 Gregor Fuhrmann 1 Pamp;#229;l Johansen 3 Jean-Christophe Leroux 1 Marc A Gauthier 2
1Swiss Federal Institute of Technology Zurich Zurich Switzerland2INRS Varennes Canada3University Hospital of Zamp;#252;rich Zurich SwitzerlandShow Abstract
In comparison to neutral linear polymers, functional and architecturally complex (i.e., non-linear) polymers offer distinct opportunities for enhancing the properties and performance of therapeutic proteins. However, understanding how to harness these parameters is challenging, and studies that capitalize on them in vivo are scarce. This presentation will cover this important topic with emphasis on two types of therapeutic proteins: ones for which long circulation in the bloodstream is desired, and ones for which retention and/or stabilization in the gastrointestinal tract is desired.
We will first present how the modification of an enzyme with a polymer of appropriate architecture can impart exceptionally low immunogenicity (e.g., generation/recognition of antibodies in vivo), with a commensurably low loss of therapeutic activity.[1,2] Secondly, we will also discuss how the modification of an enzyme with a polymer bearing appropriate functional groups can promote its stability (and thus therapeutic activity) at different locations in the gastrointestinal tract. Furthermore, functional polymers that interact with mucin will be shown to promote retention in the upper part of the gastrointestinal tract, and thus enhance the therapeutic activity of enzymes at this location. Overall, the importance of the findings will be framed with context to selected relevant diseases that stand to benefit most from the presented concepts. This work was supported by the Swiss National Science Foundation (310030_135732) and the Sassella Stiftung.
 Liu, Tirino, Radivojevic, Phillips, Gibson, Leroux, Gauthier. Advanced Functional Materials. 2013, 23, 2007
 Liu, Johansen, Zabel, Leroux, Gauthier. Submitted
 Fuhrmann, Grotzky, Lukicacute;, Matoori, Yu, Luciani, Walde, Schlüter, Gauthier, Leroux. Nature Chemistry, 2013, 5, 582
5:45 AM - H3.08/B3.08
Cellular and Biomolecule Isolation on Biodegradable Nanostructured Coatings
Eduardo Reategui 1 2 Nicola Aceto 3 James Sullivan 3 Anne Jensen 1 Eugene Lim 4 Mahnaz Zeinali 1 A. J. Aranyosi 1 Wei Li 5 Steven Castleberry 5 Aditya Bardia 3 Lecia Sequist 3 Daniel Haber 3 Paula Hammond 5 Mehmet Toner 1 Shannon Stott 3
1Massachusetts General Hospital Charlestown USA2Harvard Medical School Charlestown USA3Massachusetts General Hospital Cancer Center Charlestown USA4Massachusetts Institute of Technology Cambridge USA5Massachusetts Institute of Technology Cambridge USAShow Abstract
Nanostructured materials have been used as substrates for sensitive cellular or biomolecule recognition due to their high surface-area to volume ratio and biocompatibility. Whereas the deposition of these nanomaterials on surfaces is often irreversible, the analysis of the isolated biological samples is often limited to on-device microscopic imaging and spectroscopy applications. Therefore, biodegradable nanostructure substrates will facilitate the recovery of cells or biomolecules for downstream analysis (e.g., DNA, RNA, or proteomic analysis) and cell culture. Here, we describe a biodegradable nanostructured coating that allows for either temperature-responsive or mechano-sensitive degradation. The ultrathin coating (135.2 nm ± 8.6 nm) was formed by a layer-by-layer (LBL) deposition of biotinylated gelatin and neutravidin. Nanoroughness on the coating (30.7 nm ± 6.1 nm) was achieved by the incorporation of 70 nm streptavidin nanoparticles that were physisorbed directly on the gelatin coating. Temperature degradation of the applied coating to a glass or PDMS surface was achieved by raising the temperature to 370C; allowing their complete removal after 10 min. For local degradation of the coating, a normal force was applied through a frequency-controlled 80 µm microtip to dislodge partial regions of the coating, mimicking thixotropic hydrogel behaviors.
To demonstrate the biocompatibility and extremely sensitivity of the nanocoating, we used it for circulating tumor cells (CTCs) isolation and recovery. CTCs are extremely rare cells present in the blood stream of metastatic cancer patients (1 CTC per 109 blood cells) and their isolation and processing constitutes a technological challenge. We incorporated the nanocoating on our microfluidic HBCTC-Chip1 with tumor-cell specific antibodies at its surface (anti-EpCAM, anti-EGFR, anti-HER2). The clinical value of the nanocoating-microfluidic system was established when CTCs were detected in 87.5 % of patients with metastatic breast and lung cancer. The temperature degradation mechanisms of the nanocoating allowed recovery of 98.3 % ± 3.5 % of target cells with viabilities up to 92.03 % ± 4.5 %. Additionally, the frequency-controlled microtip allowed the recovery of individual CTCs from cancer patients that were analyzed for the presence of driver mutations in the PIK3CA (H1047R) and EGFR (exon 19 deletion and L858R) oncogenes.
In summary, our nanoscale, reversible biomaterial would enable and/or improve downstream assays through the release of any surface (e.g. beads, glass surfaces) that was initially employed to selectively isolate cells, proteins or DNA from a biological specimen.
1 Stott, S. L. et al. Isolation of circulating tumor cells using a microvortex-generating herringbone-chip. Proceedings of the National Academy of Sciences107, 18392-18397, doi:10.1073/pnas.1012539107 (2010).
H4: Poster Session I: Inorganic Biodevices
Monday PM, December 01, 2014
Hynes, Level 1, Hall B
9:00 AM - H4.01
Purification of Microvesicles by Standing Surface Acoustic Wave (SSAW)
Kyungheon Lee 1 Huilin Shao 1 Ralph Weissleder 1 Hakho Lee 1
1Massachusetts General Hospital Boston USAShow Abstract
Circulating microvesicles (MVs) have emerged as a promising surrogate for tissue-based markers, enabling non-invasive, real-time disease monitoring. Purifying MVs for downstream analyses, however, still remains a challenging task, which often involves time-consuming and extensive procedures (e.g., ultracentrifugation, multiple filtration). We herein present a new microfluidic platform for MV isolation and enrichment from clinical samples. The system utilizes acoustophoresis to size-selectively separate MVs. Interdigitated electrodes, patterned on LiNbO3 substrate, were used to generate standing surface acoustic wave (SSAW) inside a microfluidic channel, and the resulting acoustic radiation force separated MVs according to their size and density. The design and operation of the device was optimized through numerical simulation. When applied to sort nanobeads, the system achieved > 90% sorting yields. We further used the system to collect MVs from pRBC (packed red blood cell) samples as well as from cell culture media. The microfluidic-SSAW device successfully isolated and enriched pure MV population, which was confirmed by downstream molecular analyses (Western blotting). Based on label-free and continuous in-flow separation, the developed platform could be an ideal tool for fast preparation of intact MVs.
9:00 AM - H4.02
Importance of Diode Circuit Element in Electrolyte-Oxide Interface for Nanopore Ion-Transistors
Sung-Wook Nam 1 Binquan Luan 1 Eduard A Cartier 1 Marinus Hopstaken 1 Ajay K Royyuru 1 Gustavo A Stolovitzky 1
1IBM T.J. Watson Research Center Yorktown Heights USAShow Abstract
Nanopore ion transistors are electrofluidic elements conceived to manipulate the transport of molecular species through nanopores using electric fields. In this work, we report on a newly discovered diode circuit element existing in the electrolyte-oxide interface, and its importance for electrofluidic gating in ion transistors. We built sub-20 nm nanopore ion transistor devices and characterized ionic transport of KCl electrolytes. Simultaneous monitoring of electric currents of source (Is), drain (Id) and gate probes (Ig), allowed us to characterize both ionic and interfacial transports, as a function of gate voltage (Vg). Ionic transport through the nanopore was modulated such that negative (-) gate voltage bias induced an increase of ionic current, representing p-type transport, suggesting that the majority carrier contributing to ionic transport is positively charged potassium ion (K+) which screens the surface charges of pore wall. Interestingly, a characterization of Ig showed the presence of a diode circuit element in the electrolyte-oxide interface: The electric field created by negative (-) gate voltage bias reaches the electrolyte more effectively than that created by a positive (+) gate voltage bias, thus leading more efficient electrical-control over ionic transport. This diode functionality in electrolyte-oxide interface results in the unipolar transport of ion transistor. Based on the analysis of secondary ion mass spectrometry (SIMS) of the gate oxide layer, we suggest that the diode functionality is attributed to the diffusion of permeable potassium ions into the gate oxide, driven by negative (-) gate voltage biases. Our interpretation of the electrolyte-oxide interfacial effect clarifies electrofluidic gating behavior in ion transistors.
9:00 AM - H4.03
Electrochemical Etching of Silicon: High-Aspect-Ratio Nanopore Arrays on Membranes
Torsten Schmidt 1 Miao Zhang 1 Fatemeh Sangghaleh 1 Jan Linnros 1
1KTH Royal Institute of Technology Kista SwedenShow Abstract
Electrochemical etching (EE) of silicon in hydrofluoric acid has been shown to be an outstanding tool to realize a large variety of structures addressing a broad range of applications. Examples are the well-known luminescent porous silicon1 and well-defined homogenous pore arrays in the micrometer as well as sub-µm range.2-5
Nowadays, for demanding applications, such as molecular filtering and possibly sequencing of binary encoded DNA strands, solid-state membranes featuring an array of well-separated nanopores with diameters of about 2 nm are desirable. To meet these extraordinary requirements, light-assisted EE on structured silicon can be applied. The formation of nanopores, either in bulk silicon or on silicon membranes, is based on the local dissolution of surface atoms in pre-defined etching pits. Pore growth and pore diameter are, respectively, driven and controlled by the supply of positive charge carriers.
Performing EE on moderately-doped n-type bulk silicon, arrays with sub-100 nm wide pores were fabricated. In particular, straight nanopores with aspect ratios above 1000 (~19 µm deep and ~15 nm pore tip diameter) were achieved. However, inherent to the formation of such narrow pores is a radius of curvature of a few nanometers at the pore tip, which favors electrical breakdown resulting in rough pore wall morphologies.6
The Si membranes, used in our study, were fabricated on silicon-on-insulator (SOI) wafers using the Bosch process of inductively-coupled plasma etching. Array patterns in the sub-micro scale were defined on the membrane front side by optical or e-beam lithography. Electrochemical etching was then carried out individually on free-standing Si membranes, which are 100 µm in diameter and between 300 nm and 5 µm thick. So far, nanopores with diameters from 7 nm to 15 nm have been obtained on 300 nm thick membranes. To verify that pores have been etched through the whole membrane, the nanopore arrays were subjected to simple translocation experiments with fluorophore-tagged oligonucleotides. Based on optical detection, well-distinguishable single translocation events could be observed simultaneously for several nanopores (pore pitch distance 2 µm).
L. T. Canham, Appl. Phys. Lett. 57 (10), 1046-1048 (1990)
V. Lehmann et al., Materials Science and Engineering B69-70, 11-22 (2000)
P. Kleimann et al., Mater. Sci. Eng. B 69-70, 29-33 (2000)
J. Linnros et al., Physica Scripta 126, 72 (2006)
G. Laffite et al., Journal of the Electrochemical Society 158, 1 D10-D14 (2011)
T. Schmidt et al., submitted (2014)
9:00 AM - H4.04
Hybrid Fabrication of Controlled TiO2 Nanowire Arrays for Cellular Analysis
Young-Shik Yun 1 2 Jong-Souk Yeo 1 2
1Yonsei University Incheon Korea (the Republic of)2Yonsei University Incheon Korea (the Republic of)Show Abstract
According to advanced nanotechnologies in the field of biomedical engineering, an understanding of cellular responses with nanostructures becomes increasingly important. It requires a fabrication of nanostructures with a precise control of their size and positions in order to investigate the interactions between nanostructures and cellular responses. Electron beam lithography (EBL) as a top-down approach has been considered as one of the most powerful processes to fabricate and control nano-scale patterns. In this work, we fabricate Ti-based nanowires based on both top-down and bottom-up approaches using EBL and vapor-liquid-solid (VLS) method for the nanoscale resolution control of the nanowires. The size and the position of TiO2 nanowire arrays are controlled by EBL. Au-nanodot arrays are patterned on a substrate by the EBL as a seed pattern of TiO2 nanowire arrays. The nanodot arrays play an important role for catalysts using VLS method as bottom-up approach. In order to control the spacing between nanodots, we optimize the EBL process with Poly(methyl methacrylate) (PMMA) as an electron beam resist. Metal lift-off is used to transfer the spacing-controlled nanodots. The sample is then placed in a tube furnace and heated at a synthesis temperature of 850 °C. After the heat-treatment, TiO2 nanowire arrays grow from the nanodots through the VLS method. The controlled growth of TiO2 will be used to the study of interactions between nanostructures and cellular responses. We will examine the cellular response of osteoblasts as a function of the size and spacing of nanowires.
This research was supported by the MSIP(Ministry of Science, ICT and Future Planning), Korea, under the “IT Consilience Creative Program” (NIPA-2014-H0201-14-1002) supervised by the NIPA(National IT Industry Promotion Agency)
9:00 AM - H4.05
Generating and Trapping Device for Size-Controlled Microbubbles Using Patterned Carbon Nanotubes
Hiroshi Nishimura 1 Kaori Hirahara 3 2
1Osaka University Suita Japan2Osaka University Suita Japan3Osaka University Suita JapanShow Abstract
The extraordinary electrochemical properties of micrometer and nanometer sized fine bubbles, which are so-called microbubbles and nanobubbles, respectively, make them attractive for application in medical science and agriculture fields. Recently many application studies, such as bioactivation, clinical tests for bactericidal activities and wound cleaning, cleansing of seawater pipes, and so on., are already well underway, showing its potential. In addition, a method for trapping individual protein molecules using the gas-liquid interfaces on bubbles is also being developed. For promoting further applications utilizing such fine bubbles, detailed fundamental understanding is essential, especially regarding the correlation between size-dependent characteristics and resulting effects. Here we propose a novel electrochemical device using carbon nanotubes (CNTs), which can generate microbubbles with a uniform size and trap them individually to the specific addresses of the device. This device has a potential to enable us to single bubble level investigations with well-controlled sizes. It will also applicable to the manipulation or trapping of protein molecules and cells for their fundamental studies at single molecular or single cell level.
The devices proposed in this study employ patterned CNTs as the electrode for bubble generation by water electrolysis. Hole-patterned Fe catalyst was firstly fabricated at a pitch of 30#65374;200mu;m on a conductive Si substrate by photolithography process. Surface of the substrate at individual holes were insulated by 20nm thickness layer. Patterned CNTs were then fabricated on this substrate by chemical vapor deposition. After wiring the substrate to facilitate electricity from a power source, the electrode configuration was finally obtained in which only patterned CNTs exposed by insulating around the Si substrate and conductive wire.
Water electrolysis was conducted in a 10% NaOH aqueous solution using the fabricated electrode as a cathode. We found that hydrogen microbubbles generated on individual holes with a uniform size, at an applied voltage of 5 V. The experimental results showed that the bubble size can be controlled precisely by the reaction time and variation in the applied voltage. Furthermore, the bubbles still persist even after cutting off voltage. It demonstrates that the device can also function as a reservoir for bubbles with fixed diameter. Minimum diameter of the bubbles depended on the size of CNT hole pattern. It is expected to be possible to operate smaller bubbles less than 30mu;m in further study, by developing the CNT electrode with finer patterning.
This work was supported by JSPS KAKENHI Grant No. 26286024. Photolithography process was supported by the Nanofabrication Platform in Nanotechnology Open Facilities, Osaka University.
9:00 AM - H4.06
Use of Selenium Nanoparticles to Treat Head and Neck Squamous Cell Carcinoma (HNSCC)
Christopher Edward Hassan 1
1Northeastern University Boston USAShow Abstract
Selenium nanoparticles have been found to protect cells with normal p53 genes from cancer medications such as cisplatin and paclitaxel, while simultaneously leaving cells with mutant p53 proteins vulnerable to such drugs. This has allowed for higher doses than would otherwise be safe to administer. These observations will be applied to head and neck squamous cell carcinoma (HNSCC) cells. The protective selectivity of elemental selenium nanoparticles on these cells, as well as the ambient mucus which can also carry the mutated p53 protein, will be analyzed. Selenium functionalized with PEG will also be explored as a possible option. Additionally, the mechanism for converting glutathione and selenite to glutathione disulfide and elemental selenium will be analyzed.
9:00 AM - H4.07
Dextran Coated Cerium Oxide Nanoparticles as Antioxidants
Ece Alpaslan 1 Amit K. Roy 1 Thomas J. Webster 2
1Northestern University Boston USA2Northestern University Boston USAShow Abstract
The presence of Reactive Oxygen Species (ROS) and Reactive Nitrogen Species (RNS) contribute to the progression of several human diseases. In clinical applications, antioxidants as Vitamin C and E and other free radical scavengers have only achieved limited success due to a lack of targeted delivery. However, recent advancements in nanotechnology have enabled targeted delivery, as well as the elimination and control of oxidation reactions, as smaller sizes induce greater oxidative stress. Some of the most studied nanomaterials, which may act as potential antioxidants, are rare earth oxide nanoparticles, fullerenes and carbon nanotubes. With recent reports on cerium oxide nanoparticles (CNP) being neuroprotective, radioprotective, and anti-inflammatory, CNP may be a novel potential free radical scavenger. Considering these facts, CNP may promote cell survival under oxidative stress to limit ROS and RNS damage.
The objective of this study was to determine whether human dermal fibroblast (HDF) cells are able to recover from cytotoxic reagents as hydrogen peroxide (H2O2) or hydroquinone (HQY) in the presence of CNP.
Sub 5 nm dextran coated CNPs were synthesized from 5 mL aqueous solutions of 1 M cerium nitrate (Sigma Aldrich, St Louis, MO) and 10 mL of 0.1 M dextran T-10 (Pharmacosmos, Holback, Denmark) and these solutions were added drop wise to 30 mL of a 30% ammonium hydroxide (Sigma Aldrich, St. Louis, MO) solution while stirring for 24 hours at 25 omicron;C.
TEM results revealed that the particles were around 3 nm and Dynamic Light Scattering results confirmed that there was no significant change in the size of the particles after storing them for a month.
Cell proliferation was assessed using MTS kit per the manufacturer&’s instructions. HDF (ATCC® PCS-201-010trade;) cells were cultured using DMEM (ATCC® 30-2003trade;), 10% FBS (ATCC® SCRR-30-2020trade;) and a 1% penicillin-streptomycin solution (ATCC® 30-2300trade;). The cells were seeded at 5,000 cells /well, allowed to adhere for 24 hours and the following day, the culture was treated with cytotoxic agents like H2O2 or HQY with the concentration range from 100 to 800µM. After 24hrs of incubation, the MTS reagent was added and was determined. A dose of 400µM for both cytotoxic agents was found effective in killing 50% of the cells. In order to determine the cyto-protective function of CNP, some of these cells were preincubated with ceria at 500 µg/mL concentration for 24hrs followed by the addition of cytotoxic agents. The culture was incubated for 24hrs before MTS assays. Results were compared with only 400 µM of H2O2 and HQY, but not CNP treated cells.
Sub 5 nm dextran coated CNP were synthesized and cultured with HDF cells, which were then treated by cytotoxic reagents. The results showed that CNP treated cells were able to recover from the oxidative damage /cytotoxicity exerted by the drugs, suggesting that CNP may act as antioxidants within the body.
9:00 AM - H4.08
A Mucus- and Biofilm-Resistant Modification on Endotracheal Tubes
Jun Li 1 Daniel Donahue 1 Gregory Brotske 1 Phu Nguyen 1 Michael Bouchard 1 Zheng Zhang 1
1Teleflex Medical Cambridge USAShow Abstract
Mucus accumulation on medical devices such as the endotracheal tubes (ETTs) can cause serious occlusion and infection issues. Our research focused on understanding the interaction between mucin and different types of surfaces, and led to the development of a betaine-modified PVC substrate that can resist both mucus/sputum accumulation and bacterial attachment. A full-sized ETT tube was modified and exhibited a significant mucus reduction in an animal model.
Both hydrophobic and hydrophilic polymeric substrates were prepared, with their contact angles ranging from nearly zero to 130o. PVC surfaces were applied with positive, negative ,zwitterionic, and uncharged modifications. It was found that some highly hydrophobic and highly hydrophilic surfaces can resist mucus adsorption. The surfaces of betaine-modified, full size, PVC ETT exhibited a 48-65% reduction in mucus attachment in vitro, as measured by radiolabeled porcine mucin. The betaine-modified PVC ETT surfaces also reduced the attachment of S. aureus (MRSA) and C. albicans by nearly 99% and reduced P.aeruginosa by 76%. A process was developed to modify a full-sized ETT on both outside and inside surfaces. In a 5-hour sheep study betaine-modified ETTs showed a significant reduction in mucus/sputum attachment.
9:00 AM - H4.09
Microtopographic Control of Nanostructure Self-Assembly
Laith Kadem 1 Julia Purtov 1 Constanze Lamprecht 1 Christine Selhuber-Unkel 1
1Christian-Albrechts-University of Kiel Kiel GermanyShow Abstract
Here we report the use of diblock-copolymer micelle nanolithography (BCML) to create gold nanoparticle arrays on microtopographic substrates. BCML is a widely used technique to generate quasi-hexagonally arranged