Simple Direct Routes to Polymer Brush Traps and Nanostructuresfor Studies of Diffusional Transport in Supported Lipid Bilayers

摘要

Patterned poly(oligo ethylene glycol) methyl ether methacrylate (POEGMEMA) brush structures may be formed by using a combination of atom-transfer radical polymerization (ATRP) and UV photopatterning. UV photolysis is used to selectively dechlorinate films of 4-(chloromethyl)phenyltrichlorosilane (CMPTS) adsorbed on silica surfaces, by exposure either through a mask or using a two-beam interferometer. Exposure through a mask yields patterns of carboxylic acid-terminated adsorbates. POEGMEMA may be grown from intact Cl initiators that were masked during exposure. Corrals, traps, and other structures formed in this way enable the patterning of proteins, vesicles, and, following vesicle rupture, supported lipid bilayers (SLBs). Bilayers adsorbed on the carboxylic acid-terminated surfaces formed by C–Cl bond photolysis in CMPTS exhibit high mobility. SLBs do not form on POEGMEMA. Using traps consisting of carboxylic acid-functionalized regions enclosed by POEGMEMA structures, electrophoresis may be observed in lipid bilayers containing a small amount of a fluorescent dye. Segregation of dye at one endof the traps was measured by fluorescence microscopy. The increasein the fluorescence intensity was found to be proportional to thetrap length, while the time taken to reach the maximum value was inverselyproportional to the trap length, indicating uniform, rapid diffusionin all of the traps. Nanostructured materials were formed using interferometriclithography. Channels were defined by exposure of CMPTS films to maximain the interferogram, and POEGMEMA walls were formed by ATRP. As forthe micrometer-scale patterns, bilayers did not form on the POEGMEMAstructures, and high lipid mobilities were measured in the polymer-freeregions of the channels.