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Focus On Materials
Materials Day 2006 - Posters
Biomaterials and Medical Devices
- A01 - Nanocolloids for Nanomedicine
S. M. Rouse, E. I. Altinoglu, C. I. Phillips, J. A. Nelson, J. H. Adair
Abstract: Nanocolloids with a core-shell architecture exhibit properties attractive for a range of nanomedical applications. Reverse micelle synthesis provides flexibility in the design of these nanoscaled particles. Various syntheses have been conducted to tailor overall size, shell protection and resorbability, and surface functionalization for site-specific interaction. Effective dispersion is critical for medical applications, thus a diffusion controlled chromatography technique has been developed in washing the synthesized nanocolloid particles. These nanocomposite vehicles can be used to encapsulate a range of bioactive molecules for an even broader range of functionality. Current shell-matrix materials (including silica, calcium phosphate and calcium phospho-silicate) provide targeted and extended-release delivery of insoluble or unstable therapeutic agents, as well as long-term, high resolution emission of fluorescent dyes for bioimaging.
URL: http://www.mri.psu.edu/centers/pmc
- A03 - Lignocellulosic Materials Research
N. R. Brown
Abstract: This poster will provide an overview of recent activities in our research group. Our current focus is wood adhesion, but we will soon venture into the area cellulose nanotechnology by examining bacterial synthesis of cellulose and the morphology of the wood cell wall. In the wood adhesion studies, performance is related to molecular properties of the wood-adhesive interphase. Currently we are investigating the effects of wood anatomy on adhesive joint performance using isocyanate adhesives. Another project utilizes potential coupling agents for reducing adhesive delamination. Also, we are studying the effects of varied RF cure cycles on joint performance. This summer we will be exploring bacterial cellulose production. Our aim is to manipulate the cellulose produced to force certain polymer chain conformations.
URL: http://www.sfr.cas.psu.edu/FACULTY/Brown.htm
- A04 - Observations of the pMDI/Wood Bondline With Differing Wood Species
T. M. Gruver, N. R. Brown
Abstract: Methylene diphenyl-di-isocyanate (pMDI) has proven itself as a strong, durable thermosetting resin for structural wood composites. Previous research has suggested that the performance of pMDI is dependent on wood species; therefore, the goal of this research is to further explore the species dependent performance of pMDI. Specifically, the effects of anatomical and chemical differences among species are considered, as well as moisture content because these variables could impact adhesive penetration and performance. Preliminary data was acquired by testing and comparing compression shear blocks modeled with respect to ASTM D-905. Adhesive penetration in the compression shear block samples was also observed with fluorescence microscopy. These findings provide more detail regarding the species dependent performance of isocyanate resins.
- A05 - Accurate Estimate of Biomolecular Concentration in Living Cells at High Spatial Resolution
R. P. Walvick, D. J. Mudaliar, A. A. Heikal
Abstract: The concentration of native biomolecules (e.g., proteins, cofactors) can be used as a reporter for health and disease diagnoses. Fluorescence is a noninvasive approach for qualitative imaging of these biomolecules. However, quantitative estimate of the concentration of these biomolecules requires in-depth understanding of how the heterogeneous cellular environment might affects their fluorescence properties. Here we present a fluorescence-based method for accurate analysis of molecular concentration imaging using a combination of steady-state and time-resolved two-photon fluorescence lifetime microscopy. As proof of this concept, we use human breast cancer cells, stained with a mitochondrial marker Rhodamine 123, as a model system. The advantage of our approach relies on the sensitivity of fluorescence lifetime to the cellular environment and molecular structure. Monitoring the variation in biomolecular concentration can be a useful tool in medical diagnosis.
URL: http://www.bioe.psu.edu/faculty/Heikal.html
- A06 - Lipid-Phase Specificity of Rotational Diffusion and Molecular Orientation
D. J. Mudaliar, R. P. Walvick, A. A. Heikal
Abstract: Cellular plasma membranes are heterogeneous, dynamic and complex systems that regulate numerous biological processes such as signal transduction and protein trafficking. Lipid phase (i.e., order) affects the fluidity and mechanical properties of the biomembranes as well as the transport characteristics of membrane proteins and biomolecules. Recent studies suggest the existence of specialized lipid microdomains (or rafts) that serve as portals of entry for various pathogens and toxins. Very limited effort has been devoted to imaging rotational diffusion of phase-specific markers in biomembranes as a probe of lipid domains. Here, we present a novel approach for monitoring the spatio-temporal fluctuation of lipid phases in giant unilamellar vesicles (GUVs) as a model system that mimics biomembranes. Our preliminary results provide a molecular perspective of the dynamics of lipid phases and will ultimately help our understanding of their structure-function relationship in living cells.
URL: http://www.bioe.psu.edu/faculty/Heikal.html
- A07 - Novel Antimicrobial Polymers and Composites
V. Sambhy, S. Tandukar, A. Sen
Abstract: Research encompassing the design of novel antimicrobial polymers and composites will be described. Possible applications include food packaging, sterile surfaces, decontamination kits and personal protective equipment. These materials destroy harmful pathogens simultaneously through several different mechanisms. The use of polymeric materials with multiple antibiotic groups results in increased potency and decreased chance of developing resistance.
- A09 - Patterning Complexity into Supported Planar Bilayers
K. Vats, M. Kyoung, E. D. Sheets
Abstract: We are probing the relationship between membrane structure and biological function in living cells and on biomimetic model membranes using microlithography and fluorescence microscopy to probe the molecular interactions that lead to lipid domain formation and domain dynamics. Complexity is built into supported bilayers by pattering domains via a polymer lift-off approach. We are initially using a fluid di12:0PC, and gel phase di15:0PC or di16:0PC. We first create arrays of 5 µm or 10 µm squares, which is supported on a glass substrate. We then incubate with the other component to introduce complexity. The complex bilayers retain their patterns and form single, continuous bilayers. Fluorescence correlation spectroscopy shows that the fluid phase lipids are laterally mobile. By following the dynamics of domains and individual lipids, we will understand how lipid structure controls biological function. Our approach may also allow us to construct improved biosensors.
URL: http://research.chem.psu.edu/edsgroup
- A10 - Mechanisms of Blood-Material Interactions in Biomaterial-Induced Thrombosis
C. A. Siedlecki, E. A. Vogler, Z. Guo, K. R. Milner, A. Agnihotri, K. Chatterjee, P. Soman, H. Yamanaka, M. A. Hussain, K. M. Bussard, R. Miller
Abstract: Patients who require medical devices that contact blood are at risk of developing clots (thrombi) on the device surface. When biomaterials contact blood, plasma proteins adsorb at the interface and trigger the blood coagulation cascade, facilitate blood platelet adhesion, and eventually cause biomaterial-induced thrombosis. Anti-coagulation therapy slows the process but these treatments lead to complications such as increased risks of bleeding. In order to develop new biomaterials, we study the interactions of blood and blood components with surfaces at levels ranging from single molecules (Å to nm scale) up to macroscopic blood clots (cm) in order to understand how thrombosis is initiated. The goal of our studies is to elucidate relationships between surface properties of materials and the biological response. These studies provide guidance for rational development of blood-compatible biomaterials that will be critically important to development of new medical devices.
- A11 - Ordered Sub-Micron Surface Textures Reduce Blood Platelet Adhesion to Polyether(Urethane Urea)
K. R. Milner, M. Balmer, H. Yamanaka, A. J. Snyder, C. A. Siedlecki
Abstract: Platelet adhesion is a key event in thrombus formation on medical devices. We present a method for reducing adhesion to biomedical materials at low shear stress via surface texture. Pillars were fabricated on a biomedical polyether(urethane urea) (PUU) via replication molding. Ordered pillar arrays were fabricated on silicon wafers with height of ~700nm and width and separation of either ~700nm or ~400nm. Silicone molds were cast. PUU replicas were prepared by casting over the molds. Controls were prepared by casting on smooth silicone. The variation in adhesion with shear stress was assessed using a rotating disk, exposing bovine platelet-rich plasma to 0-67 dyn/cm2. Platelet adhesion reduced with increasing shear on smooth and textured PUU and was equivalent for shear >5 dyn/cm2. At lower shear adhesion was reduced on textured PUU, significantly so for 700nm pillars. In summary, surface texture may act to reduce platelet adhesion to biomedical PUU at low shear stress.
- A12 - From Cells to Tissue in a Materials Scientist's Bioreactor
R. Dhurjati, E. A. Vogler
Abstract: The problem of maintaining cells/tissue long-term (>120 d) in vitro for biomaterials/tissue engineering applications is solved by a unique bioreactor design incorporating polymeric materials judiciously chosen to enhance the physiologic state of growing cells. Development of differentiated, collagenous bone tissue (biosynthetic osteoid) from disaggregated osteogenic cells (mouse calvarium MC3T3-E1) over 120 d culture is demonstrated on both 2-D polymer substrates as well as 3-D hydroxyapatite scaffolds. The bioreactor thus shows promise as a new in vitro tool for development of orthopedic biomaterials or bone/cartilage tissue engineering and highlights the role materials scientists can play in close collaboration with cell biologists.
URL: http://www.ems.psu.edu/%7Evogler/EAVogler.htm
