RATIONAL PATTERN DESIGN FOR IN-VITRO CELLULAR NETWORKS USING SURFACE PHOTOCHEMISTRY

The ability to create patterns of specific silane monolayers by deep u ltraviolet lithography has been previously demonstrated, and prelimina ry attempts have been made to use these patterns to control adhesion a nd outgrowth of neurons and other types of mammalian cells. Here we re port characterization of the mechanisms involved in these photoinitiat ed processes and their utility in various strategies for creating patt erns for biologically relevant systems. We have divided the mechanisms into three general classes. The first is surface photolysis of the si lane monolayer, which appears to proceed by a purely photochemical mec hanism. The second mechanism involves direct photochemical conversion of a terminal functional group on a silane monolayer into a species wi th altered properties, e.g., the conversion of a thiol to a more oxidi zed form that inhibits the subsequent adhesion of proteins. The third is a photolytic degradation of the monolayer. The mechanisms have been probed by x-ray photoelectron spectroscopy, ellipsometry, and wettabi lity measurements. One result of these investigations has been the dev elopment of better strategies to create patterns. Controlled growth of hippocampal neurons on high resolution patterns is presented as demon stration of the efficacy of these strategies in spatially dictating ce ll adhesion. These results have important implications in designing in vitro culture systems to study well-oriented neuronal systems.