Synthesis of Silica-Coated AgI Nanoparticles and Immobilization of Proteins on Them

This paper describes a method for preparing silica-coated silver iodide (AgI/SiO(2)) particles and immobilizing proteins on the AgI/SiO(2) particles. Colloid solution of AgI particles was prepared by mixing AgClO(4) aqueous solution and KI aqueous solution. Silica-coating of the AgI particles was performed by adding 3-mercaptopropyltrimethoxysilane, tetraethylorthosilicate/ethanol solution and NaOH aqueous solution successively to the AgI colloid solution. TEM observation revealed that the AgI nanoparticles were coated with uniform silica shell. The AgI/SiO(2) particles were surface-modified with 3-aminopropyltrimethoxysilane and succinic anhydride. It was confirmed by XPS measurement that amino group or carboxyl group was introduced onto the AgI/SiO(2) particles. Protein-immobilization was performed in aqueous solution with bovine serum albumin (BSA) in the presence of the surface-modified AgI/SiO(2) particles. UV-VIS absorption spectroscopy revealed that the BSA was adsorbed on the surface-modified particles.