Applications of nanoporous gold for the immobilization of biomolecules

Nanoporous gold (NPG) has attracted much attention in numerous applications including use in chemical sensors, fuel cells, and biosensors. NPG is a versatile nanomaterial fabricated by dealloying a low carat gold alloy or by electrodeposition of a gold alloy containing less than 50% gold followed by treatment in concentrated nitric acid. The structural and physical properties of NPG were characterized using scanning electron microscopy (SEM), atomic force microscopy (AFM), Brunauer-Emmett-Teller (BET) analysis, and cyclic voltammetry. NPG has high a surface area, is biocompatible, and is stable against oxidation. The pore sizes range from 20-200 nm and are tunable by preparation method. Due to these properties, NPG is an excellent matrix for the formation of self-assembled monolayers, and can be functionalized with biomolecules such as enzymes, antibodies, and antigens. In this investigation, NPG was studied for its applications as a solid support for the development of immunoassays for the biomarkers, prostate specific antigen (PSA) and carcinoembryonic antigen (CEA).