Surface Modification of Siliceous Materials Using Maleimidation and Various Functional Polymers Synthesized by Reversible Addition-Fragmentation Chain Transfer Polymerization

摘要

A novel surface modification method was investigated. The surface of siliceous materials was modified using polystyrene, poly(acrylic acid), poly(N-isopropylacrylamide), and poly(p-acrylamido-phenyi-α-mannoside) synthesized by reversible addition—fragmentation chain transfer polymerization. Thiol-terminated polymers were obtained by reduction of the thiocarbonate group using sodium borohydride. The polymers were immobilized on the surface via the thiol—ene click reaction, known as the Michael addition reaction. Immobilization of the polymers on the maleimidated surface was confirmed by X-ray photoelectron spectroscopy, infrared spectroscopy, and contact angle measurements. The polymer-immobilized surfaces were observed by atomic force microscopy, and the thickness or the polymer layers was determined by ellipsometry. 1 he thickness of the polymer immobilized by the maleimide—thiol reaction was less than that formed by spin coating, except for polystyrene. Moreover, the polymer-immobilized surfaces were relatively smooth with a roughness of less than 1 nm. The amounts of amine, maleimide, and polymer immobilized on the surface were determined by quartz crystal microbalance measurements. The area occupied by the amine-containing silane coupling reagent was significantly less than the theoretical value, suggesting that a multilayer of the silane coupling reagent was formed on the surface. The polymer with low molecular weight had the tendency to efficiently immobilize on the maleimidated surface. When poly(p-acrylamidophenyl-α-mannoside)-immobilized surfaces were used as a platform for protein microarrays, strong interactions were detected with the mannose-binding lectin concanavalin A. The specificity of poly(p-acrylamidophenyl-α-mannoside)-immobilized surfaces for concanavalin A was compared with poly-L-lysine-coated surfaces. The poly-L-lysine-coated surfaces nonspecifically adsorbed both concanavalin A and bovine serum albumin, while the poIy(p-acrylamidophenyl-α-mannoside)-immobiIized surface preferentially adsorbed concanavalin A. Moreover, the poly(p-acrylamidophenyl-α-mannoside)-immobilized surface was applied to micropatterning with photolithography. When the micropattern was formed on the poly(p-acrylamidophenyl-α-mannoside)-spin-coated surface by irradiation with ultraviolet light, the pattern of the masking design was not observed on the surface adsorbed with fluorophore-labeled concanavalin A using a fluorescent microscope because of elution of poly(p-acrylamidophenyl-α-mannoside) from the surface. In contrast, fluorophore-labeled concanavalin A was only adsorbed on the shaded region of the poly(p-acrylamidophenyl-α-mannoside)-immobilized surface, resulting in a distinctive fluorescent pattern. The surface modification method using maleimidation and reversible addition—fragmentation chain transfer polymerization can be used for preparing platforms for microarrays and micropatterning of proteins.