Quantification of human immunoglobulin G immobilized on gold-coated silicon chip for biosensing applications

The most important aspect of biosensor development with high sensitivity is the oriented immobilization of antibodies on the solid substrate. Human IgG was immobilized on gold-coated silicon employing protein A, protein G and neutravidin immobilization procedures. The amount of human IgG immobilized was analyzed by 3, 3', 4, 4'-tetramethyl benzidine (TMB) substrate assay and was maximum when protein A immobilization procedure was followed. Human IgG coated biosensing surface was regenerated by treatment with glycine-HCl buffer (50 mM, pH 2.2). Atomic force microscopy was used to analyze the distribution of biomolecules immobilized on gold-coated silicon. Our study indicates that human IgG molecules were uniformly bound to gold-coated silicon by protein A immobilization procedure.