Study on specific binding capacity of protein dependent on poly(Oligo(ethylene glycol) methacrylate) films grown from mixed SAMs

Abstract

I. We investigated specific binding capacity of target proteins and nonspecific adsorption property by varying the lateral density between polymer brushes grown from mixed SAMs. pOEGMA films were grown from mixed SAMs consisted of UDT and ATRP-initiator on gold substrates. After polymerization, the films were activated, and then biotin coupling was treated on the films for studying specific binding capacity of streptavidin. We found that specific binding capacity of protein was influenced by varying lateral density between polymer brushes. Moreover, the nonspecific binding/adsorption property of fibrinogen and lysozyme was detected by increasing $^{sol}\chi_{UDT}$ values ranging from 0.4 to 0.8. However, the lateral density effect is disappeared by increasing polymerization time. From our results, we expected that as increasing the pOEGMA films thickness, lateral density effect did not impacted on the biotinylated pOEGMA films; the biotinylated pOEGMA films grown from mixed SAMs have only lateral effects under 8~10 nm dried ellipsometric thickness of that films. In the AFM study, we confirmed that the gap between the polymer brushes on the surface was introduced by adding UDT to the solution of mixed SAMs. In addition, we found that all the surface areas were covered by about 8~10 nm dried ellipsometric thickness of pOEGMA films. From the AFM results, we hypothesized that the phenomena, such as starting saturation of specific binding capacity of streptavidin, decreasing or nothing of nonspecific binding/adsorption property of protein, and determining the point about the lateral density effects, related to the films thickness because 8~10 nm dried ellipsometric thickness of the biotinylated pOEGMA films covered almost all of the surface areas. II. Herein we report selective immobilization of proteins onto cyclic olefin copolymer (COC) surface. We modified the surface with Azide-ATRP initiator by UV irradiation. After introduction of Azide-ATRP initiator on C...