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In this paper, we have developed a novel multilayer system composed of 3-glycidoxypropyltrimethoxysilane (GPTS); 2,2’-(ethylenedioxy)diethylamine (EDA) and protein A on the Si(100) surface for oriented immobilization of immunoglobulin G (IgG) molecule. Effects of dipping time and solution concentration on the formation of GPTS and EDA overlayers were investigated. Thickness of the GPTS and EDA overlayer was observed about 3.72 nm and 4.54 nm during the first 1 h, respectively. After these time intervals, GPTS and EDA molecules were formed as a multilayer. Surface morphologies of the prepared samples were also examined by using imaging ellipsometry and atomic force microscopy (AFM). Furthermore, antigen-antibody interaction studies on the designed surface were carried out by using protein-A and fluorescein-labeled immunoglobulin (IgG) molecules. The fluorescence images obtained by fluorescence microscopy showed that while the amino-terminated surface (EDA/GPTS/Si) demonstrate poor fluorescence signal, the designed multilayer system (Protein-A/EDA/GPTS/Si) shows more fluorescence signal with random distributions. The results indicated that the protein A-terminated surfaces could be used to orient immobilization of IgG molecules in a highly oriented manner and maintain IgG molecular functional configuration on the multilayer system. |