Preparation and Characterization of Porous Gold and its Application as a Platform for Immobilization of Acetylcholine Esterase.

We report a method for fabrication of free-standing porous gold material with high surface area, and well-defined, tunable pore morphology. Porous gold is formed via a simple procedure which involves an acidic treatment of a commercially available complex white-gold alloy. We used SEM and AFM techniques to characterize the surface morphology, size and shape of the meso-pores as well as the surface roughness of the prepared porous gold samples. Formation of self-assembled monolayers of a flavin sulfide on the gold surface was used to estimate the total surface area of porous gold material. The monolayers were found to be electrochemically active by cyclic and square-wave voltammetry. It was found that 24 hour HNO(3) treatment gave a 12,400 times surface enlargement and resulted in a surface area of 14.2 m(2)/g, whereas 72 hour HNO(3) treatment resulted in a 6900 times surface enlargement and a surface area of 8.7 m(2)/g. In addition, the enzyme acetylcholine esterase was immobilized on the different porous gold surfaces in order to demonstrate biocompatibility of the porous gold material. Kinetic parameters and the amount of the immobilized acetylcholine esterase were determined.