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, 3ƍ, 4, 4ƍ-
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 procedur