Next Generation Biomaterials: Advanced Biomaterials
Sponsored by: MS&T Organization
Program Organizers: R. Narayan, UNC/NCSU Joint Department of Biomedical Engineering; Kalpana Katti, North Dakota State University; Kajal Mallick, University of Warwick; Vilupanur Ravi, California State Polytechnic University, Pomona; Varshni Singh, Louisiana State University
Wednesday 8:00 AM
October 19, 2011
Room: C215
Location: Greater Columbus Convention Center
Session Chair: Varshni Singh , Louisiana State University ; Federico Rosei , INRS
8:00 AM Invited
Probing Molecular Polarization at Interfaces of De Novo Proteins and Electrode Surfaces: Kendra Kathan-Galipeau1; Bohdana Discher,1; Dawn Bonnell1; 1U Penn
Novel approaches to energy harvesting and biosensing would exploit optoelectronic processes such as those found in proteins that occur in nature. The ability to engineer simpler proteins with optoelectronic function enables control over assembly, and properties. In order to design systems the proteins need to be attached to electrodes and the properties in non-liquid environments must be understood. This talk will describe the simultaneous detection of electron transport and of optical absorption on dielectric polarizability in oriented peptide single molecular layers. This requires a peptide design strategy to control protein/electrode interface interactions and induce optical activity. A new method to probe electronic, dielectric, and optical properties at the single molecular layer level is demonstrated. The combination enables a quantitative comparison of the change in polarization volume between the ground state and excited state in a single molecular layer in a manner that allows spatial mapping relevant to ultimate device design.
8:20 AM Invited
Aligned Nanofiber Multiwell Plates for Cancer Research: John Lannutti1; Jed Johnson2; 1The Ohio State University; 2Nanofiber Solutions LLC
Electrospinning, like many materials processes, consists of a large number of controllable factors. Through careful monitoring, microstructures consisting of highly aligned polymer nanofibers can be created. Utilizing this, a culture system encouraging cell migration along parallel nanofibers has been created. NanoFiber Solutions (NFS) LLC was formed in 2009 to manufacture and market multi-well cell culture plates containing such highly aligned nanofiber. Historically, cell culture has been performed on flat tissue culture polystyrene (TCPS) because it is cheap and optically transparent. However, living organisms are made up of an extracellular matrix presenting specific physical structures and mechanical support to cells. Not surprisingly, drugs developed using TCPS as an in vitro substrate experience>80% clinical failure. In contrast, aligned nanofiber deliberately recapitulates the microtopography of white matter in the brain. An example of the advantages such nanofibers confer is that brain cancer cells show outward migration that can be inhibited by anti-migratory drugs.
8:40 AM
An Experiment-Simulation Approach to Determine Electrospun Fiber Properties: Greg Ebersole1; Jackie Ohmura1; Heather Powell1; Peter Anderson1; 1The Ohio State University
Constitutive properties of electrospun fibers may be determined from elaborate single-fiber testing modes. This work proposes a complementary experiment-simulation approach. Specifically, finite element simulations are developed that capture discrete fiber straightening, reorientation, and contact during scaffold deformation. Model inputs are initial fiber geometries and fiber mechanical properties. The former is provided by confocal images of scaffolds prior to deformation. The latter is unknown but is determined by tuning the simulations to reproduce two key experimental features: (1) statistical descriptions of changing fiber shape and orientation with deformation and (2) uniaxial scaffold stress-strain response. The results reveal the intrinsic, nonlinear response of hydrated, electrospun, collagen fibers embedded in a scaffold. In the process, we introduce a statistical description of fiber shapes based on Fourier coefficients and discuss extensions of the method to study time-dependent, viscoelastic response.
9:00 AM Invited
Iron/Iron Oxide Core/Shell Nanoparticles for Magnetic Hyperthermia Treatment: I. Baker1; Katsiaryna Kekalo1; 1Dartmouth College
Magnetic nanoparticles accumulated in tumors either by direct injection or by using tumor-targeted antibodies introduced though the vasculature and subjected to an alternating magnetic field (AMF) are being pursued for cancer therapy. The localized heating of the tumor, via nanoparticle heating from the AMF, to 44-45oC for sufficient time causes apoptosis of the tumor cells. This presentation will discuss the preparation of novel iron/iron oxide core/shell nanoparticles for this purpose using a microemulsion method and their characterization using scanning electron microscopy, transmission electron microscopy and vibrating sample magnetometry. The particles are produced with a cetyl trimethyl ammonium bromide coating, which is subsequently replaced with either a phospholipid or dextran coating. The effects of these coatings on both the nanoparticles’ magnetic properties and heating behavior in an alternating magnetic field will be discussed. A comparison with the behavior of dextran-coated iron oxide nanoparticles will be presented. Support: NIH grant 1U54CA151662-01.
9:20 AM Invited
Nanoscale Modification of Biomaterials to Control Cell Growth: Federico Rosei1; 1INRS
Modifying the nanostructure/chemistry of materials allows to optimize their properties [1]. Our strategy rests on creating nanopatterns that act as surface cues [2,3] and affect cell behavior. Chemical oxidation was found to create unique nanostructured topographies [4], becoming a general strategy for affecting biocompatibility. Our treatment promotes the growth of certain cells while inhibiting that of others, without using growth factors. Nanostructured Ti surfaces selectively inhibit fibroblast growth and promote osteogenic cell activity [5] in vitro. Further enhancement of mechano-biocompatibility may occur by coating with spider silk [6]. Enhancement of antibacterial properties using nanoscale strategies will also be discussed. [1]F Rosei, J Phys Cond Matt 16, 1373 (2004) [2]F Variola et al, Small 5, 996 (2009) [3]F Variola et al, Biomaterials 29, 1285 (2008) [4]F Vetrone et al, Nanolett 9, 659 (2009) [5]L Richert et al, Adv Mater 20, 1488 (2008) [6]C Brown et al, Nanoscale in press (2011)
9:40 AM Break
10:00 AM Invited
Bio-Doped Metal Oxides for High-Throughput Biosensors: Pelagia Gouma1; 1SUNY Stony Brook
The synergistic combination of biological entities (such as proteins, bacteria, cells, viruses) and ceramics has lead to an exciting new class of materials that may serve as the core components of the next generation of biosensors. The performance, functionality and application of such hybrid bio- ceramics systems will depend on the activity, functionality, and interaction of entrapped biomolecules with the surrounding ceramic matrix. Requirements for successful bioencapsulation include structural, thermal and chemical stability, functionality, and accessibility of biologicals upon encapsulation. Urease-doped MoO3 sol-gel provides a model system of enzyme-doped metal oxide and a novel biosensing element, that is an active substrate for the detection of urea. The fast and selective response of the metal oxide matrix to gases(e.g. NH3) that are released from the specific biochemical reaction between the biological dopant (urease) and the analyte of interest (urea) allows for the development of conductimetric biosensing probes.
10:20 AM Invited
BioMEMS Devices and Applications of Parylene Biocompatible Coating: Varshni Singh1; Quoc Nguyen1; Martina Cihova2; Jost Goettert1; Todd Monroe1; 1Louisiana State University; 2 Karlsruhe Institute of Technology
Parylene is known for its biocompatibility and additionally possesses excellent barrier, dielectric, pin hole free, conformable, and other desired properties. It is deposited on the substrate at room temperature using the chemical vapor deposition technique. Therefore, it has immense potential with area of applications widely spread out to biological, corrosion, electronic, micro-electro-mechanical systems (MEMS), microfluidics and BioMEMS including developing novel devices. In this paper we will be presenting the results of surface modification of these films where the roughness is tailored by innovative methods in the nanometer regime. The modified surfaces will be characterized by scanning electron microscope, optical profiler, contact angle measurements, atomic force microscope, and/ or biological cells. Additionally, we will be discussing the developing of the devices using parylene coatings.
10:40 AM
PCL-Gelatin Nanofibers for Extended Drug Release: Tyler Nelson1; Hrishikesh Munj1; Carol Lee1; Heather Powell1; David Tomasko1; John Lannutti1; 1The Ohio State University
Electrospun polymer fibers exhibit a microstructure and morphology that closely mimics native extracellular matrix providing a useful tool for tissue engineering applications. Supercritical CO2 processing allows for the incorporation of local, sustainable drug delivery to electrospun fibers without altering microstructure. Previous attempts to use CO2 impregnation of electrospun polycaprolactone fibers at liquid, supercritical conditions resulted in melting. 50:50 blended PCL:gelatin electrospun fibers with or without crosslinking were impregnated with a test compound, carboxytetramethylrhodamine, using CO2 at either subcritical or supercritical conditions for 30 min. Subsequent release profiles in phosphate buffered saline at 37°C were obtained over a 25 day period. DSC, FTIR-ATR, and XRD were utilized to characterize the effects of gelatin on PCL. In the presence of gelatin, the blend scaffold was able to maintain its microstructure under liquid- and supercritical-CO2 infusion conditions. Optimizing the crosslinking, and infusion conditions resulted in finer control of release.
11:00 AM Invited
Application of Polymer-Based Microfluidic Devices for the Selection and Manipulation of Low-Abundant Biological Cells: Malgorzata Witek1; Udara Dharmasiri1; Samuel Njoroge1; Morayo Adebiyi1; Joyce Kamande1; Mateusz Hupert1; Francis Barany2; Steven Soper1; 1Louisiana State University; 2Weill Cornell Medical College
Microfluidics are providing new opportunities for diagnostics. Innovative technologies developed in our group allow for the selection, enumeration, and molecular profiling of low-abundance (<100 cells/mL) circulating tumor cells (CTCs) directly from blood, a recognized assay for the management of cancer-related diseases. Colorectal cancer cells overexpressing the integral membrane protein, EpCAM, were immunospecifically isolated using anti-EpCAM antibodies immobilized to the walls of a selection bed poised on a microfluidic device that could process >1 mL. The cells were enzymatically released from the selection surface, and hydrodynamically transported for conductivity-based enumeration through an electrodes pair. Following counting, CTCs were electrophoretically withdrawn from the bulk flow and preconcentrated into an anodic reservoir. The molecular processing invoked a strategy consisting of a primary PCR for amplification of the specific gene fragment, and an allele-specific ligation reaction to detect mutations within gene. The presence/absence of mutations in KRAS could be used to guide patient chemotherapy.
11:20 AM
Development of Magnesium-Zinc-Calcium Biodegradable Alloys: Zhigang Xu1; Christopher Smith1; Jag Sankar1; 1NC A&T State University
Magnesium alloys as biodegradable medical materials have attracted much attention in recent years and there is an urgent need for developing fully biocompatible magnesium alloys. For a magnesium alloy to be fully biocompatible, it should contain only biocompatible elements and has well controlled degradation rates. The purpose of this project is to develop novel magnesium alloys containing fully biocompatible elements, such as Zn and Ca. Alloys with different concentrations of these alloying elements are developed by melting Mg ingot and Zn and Ca granules in mild steel crucibles. Once homogenized, the melt were cast into rods. A series of heat treatment studies including solution treatments and artificial aging are performed. The microstructure and composition of the alloys were investigated by using XRD, optical microscopy, SEM, and EDS, respectively. Corrosion tests were carried out to evaluate the effects of the composition, type and parameter of heat treatments on the biodegradation rate.
11:40 AM Invited
Effect of Heat Treatment and Boron Content on the Behavior of Ti Alloys in PBS and 0.9 wt% NaCl Solutions
: Vilupanur Ravi1; 1California State Polytechnic University, Pomona
Boron additions strengthen titanium alloys; however the effect on their corrosion resistance is only recently being understood. Significant grain size refinements have been observed in the base Ti-6 Al-4 V alloy even with trace boron additions (0.05-0.4 wt%). Heat treatment of Ti-6 Al-4 V containing 0.05-0.4 wt% B additions resulted in changes in yield strength, ultimate tensile strength and fracture toughness values. The effect of the heat treatments and the subsequent microstructural changes on the corrosion resistance of these alloys is unknown. This information is crucial in determining the suitability of these alloys for load bearing applications in a corrosive medium, e.g., structural bio-implants. In this study, we focused on characterizing the corrosion resistance of titanium-boron alloys in 0.9 wt% sodium chloride (saline) solutions. Nine