Immobilization of protein streptavidin to the surface of PMMA polymer

Abstract

Immobilization of the protein streptavidin to the surface of polymethyl methacrylate (PMMA) polymer was studied by X-ray photoelectron spectroscopy (XPS) and atomic force microscopy (AFM). Different protocols were used to attach streptavidin to the PMMA surface: physical adsorption and chemical coupling. The influence of oxygen plasma treatment on the efficiency of streptavidin binding was studied. The presence of streptavidin coating on the PMMA surface was demonstrated by the appearance of N1s signal in the XPS spectra of coated PMMA samples. The XPS results have shown that oxygen plasma treatment improves binding of streptavidin to the PMMA surface. XPS results also showed that chemical coupling is more efficient than physical adsorption. In the case of physical adsorption, rinsing of the sample with water caused noticeable decrease of nitrogen concentration, while in the case of chemical coupling the nitrogen concentration was stable. AFM measurements showed that after deposition of streptavidin coating the originally smooth surface changed to dendrite structure.