The development of a novel approach to the design of microdevices

The effectiveness of protein-based microdevices depends on the ability of their surfaces to provide spatial immobilization and maintain protein bioactivities. Although methodologies for the construction of microdevices for biomedical applications have been developed, the manufacturing of microdevices remains expensive due to the high cost of materials and fabrication processes. As the surfaces display structural uniformities which restrict protein-surface interactions and consequently protein immobilization, innovative approaches to the design of surfaces are required. The approaches need to allow for the minimization of fabrication costs via efficient amplification and spatial immobilization of multiplex proteins so that the bioactivity of protein-based microdevices (e.g., microarrays) can be retained. A novel approach to the design of surfaces for microdevices has been developed and evaluated in this work. This approach is based on micro/nanostructures fabricated via laser ablation of a thin metal layer deposited on a transparent polymer. The structures of a 100 nm-range are represented by „combinatorialized‟ micro/nano-channels that allow amplified protein immobilization in a highly controlled manner. The relationship between the properties of the micro/nano-channel surface topography, physico-chemistry, and protein immobilization, for five, molecularly different proteins, i.e., lysozyme, myoglobin, alpha-chymotrypsin, human serum albumin, and human immunoglobulin has been investigated. Using quantitative fluorescence measurements and atomic force microscopy, protein immobilization on microstructures has been characterized. It has been found that the combinatorial nature of the micro/nano-channels allowed a 3 to 10-fold amplification of protein adsorption, as compared to the protein adsorption on flat, chemically homogenous polymeric surfaces. An improved methodology allowing in vitro assembled micron- and nano-scale tracks of proteins (i.e., actin) which support unidirectional translocation of beads functionalized with motor proteins (i.e., myosin) was also developed. The nanotracks composed of aligned F-actin/gelsolin bundles were formed by electrostatic condensation of F-actin/gelsolin with Ba2+. The prospects for employment of bacterial ATP producers as replacements for the energy source, and prokaryotic actin homologues as replacements for eukaryotic actin in microdevices based on molecular motor-based systems, have been explored. A search for ATP producers among 86 environmental strains of 17 genera, including 4 species of 3 genera described in this thesis has been performed. Bacteria belonging to the genera Sulfitobacter, Marinobacter and Staleya and/or Planococcus and Kocuria have been found to be promising producers of extracellular and intracellular ATP, respectively. Substitution of eukaryotic actin with inherently stable prokaryotic actin-related proteins, i.e., MreB or FtsA, may point the way to the development of the next generation of microdevices for biomedical applications.