The research objective of the proposed Scholar-in-Residence program is to apply nanofabrication technologies (e.g., microwave plasma-enhanced chemical vapor deposition and atomic layer deposition) and nanostructured materials (e.g., ultrananocrystalline diamond) to solve problems associated with biofouling and size-selective transport of nanoscale biological molecules. As part of this program, graduate student participants will perform in vitro biological characterization of nanoporous diamond membranes at the FDA?s Center for Devices and Radiological Health (CDRH) laboratories.
The information obtained in the biological characterization, materials characterization, and functional characterization studies will serve as the basis for a chemical property-physical property-performance database, which will guide the development of nanoporous diamond membranes and other nanoporous biomaterials. In this database, the relationship between in vitro cell-material interaction, protein adsorption, and several processing parameters, including diamond crystallinity, titanium nitride crystallinity, pore size, pore density, and surface morphology, will be considered. The planned research is well-suited to goals of the NSF/FDA Scholar-in-Residence program, because it combines an advanced processing method at the UNC/NCSU Joint Department of Biomedical Engineering with comprehensive biological characterization facilities at the Food and Drug Administration.
There has been recent interest in developing novel nanostructured membranes for use in hemodialysis and in other biological molecule sorting applications. Diamond exhibits chemical inertness, mechanical robustness, and excellent biocompatibility. In this completed project, we coated microporous membranes and nanoporous membranes with diamond. A 150 nm thick conformal ultrananocrystalline diamond coating was deposited on microporous silicon nitride membranes. Human epidermal keratinocytes were viable on both the uncoated and diamond-coated membranes. In addition, free-standing ultrananocrystalline diamond membranes with several nanoscale and sub-microscale pore sizes were prepared using a multi-step technique involving electron beam lithography, optical lithography, reactive ion etching, and wet etching. These membranes showed narrow pore size distributions as well as high pore densities. Several studies to understand the interactions of endothelial cells and other types of cells with diamond were also undertaken. Nitrogen-incorporated ultrananocrystalline diamond were grown on titanium alloy microneedles with microwave plasma enhanced chemical vapor deposition. In vitro electrochemical detection of two biologically relevant molecules, uric acid and dopamine, was demonstrated using these microneedles. Our studies indicate that diamond exhibits good in vitro biological properties and may be appropriate for a variety of medical device applications. The program also involved the continuation of a series of lectures and scientific demonstrations for young people and others in the community.
