Cell mimics created from the controlled synthesis and directed assembly of carbon nanofibers

Biological cells represent an engineering ideal. They are the fundamental unit of all biological systems, perform virtually any function, and operate with efficiencies unmatched by man-made creations. These capabilities result from the optimized arrangement of chemical and physical features across nanometer and micron lengths. Emerging capabilities to control synthesis and direct assembly of synthetic structures over similar length scales present the opportunity to mimic these natural structures. Vertically aligned carbon nanofibers (VACNFs) have a number of features that make them particularly well suited to the construction of cell mimics. VACNFs can be synthesized with nanometer scale dimensions, can be electrically addressed and can be deterministically grown in desired locations. Dense arrays of carbon nanofibers form semi-permeable barriers (pseudo-membranes) that can be integrated within fluidic structures or arranged as small volume (sub-nanoliter) containers. Size-dependent transport perpendicular to the orientation of the fibers can be controlled based on the wall-to-wall spacing of the individual nanofibers. Recent progress in VACNF device fabrication will be presented, focusing on efforts to tailor the effective membrane pore size, through oxide deposition and electropolymerization of polypyrrole, and to derivatize the surface of VACNFs for attachment of biomolecules such as proteins and DNA. By combining these modifications in permeability and chemical features, biologically inspired cell mimics of increasing sophistication can be constructed with the ultimate objective of emulating the structure, function, and organization of natural cells, while also providing unique capabilities in chemical recognition and separations