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.

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A new spectrophotometric method using covalently attached capture antibody labeled with alkaline phosphatase is developed for the detection of fPSA.

A new surface-tethered iterative carbohydrate synthesis (STICS) technology is presented in which a surface functionalized 'stick' made of chemically stable high surface area porous gold allows one to perform cost efficient and simple synthesis of oligosaccharide chains; at the end of the synthesis, the oligosaccharide can be cleaved off and the stick reused for subsequent syntheses.

Nanoporous gold (NPG) is a material of emerging interest for immobilization of biomolecules and -especially enzymes. NPG materials provide a high gold surface area onto which biomolecules can either be directly physisorbed or covalently linked after first modifying the NPG with a self-assembled monolayer. The material can be used as a high surface area electrode and with immobilized enzymes can be used for amperometric detection schemes. NPG can be prepared in a variety of formats from alloys containing less than 50 atomic% gold by dealloying procedures. Related high surface area gold structures have been prepared using templating approaches. Covalent enzyme immobilization can be achieved by first forming a self-assembled monolayer on NPG bearing a terminal reactive functional group followed by conjugation to the enzyme through amide linkages to lysine residues.

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Electrochemical detection without derivatization was used to detect thiol-containing degradation products of V-type nerve agents. Electropolymerization of pyrrole was used for entrapment of the biocatalyst PQQ to produce a sensor. Various parameters which affect the detection processes such as the type of the supporting electrolyte used during electrodeposition and the thickness of the polypyrrole film were examined and optimized. Electocatalytic oxidation of thiols by the PPy/PQQ electrode was strongly affected by the presence of Ca2+ cations during electrodeposition of the PPy/PQQ. Cyclic voltammetry, linear sweep voltammetry and amperometry have been used for electrode characterization. Amperometric detection of the V-type nerve agent thiol degradation products 2-(dimethylamino)ethanethiol (DMAET) and 2-(diethylamino)ethanethiol (DEAET) was performed at 0.38 V. Linear calibration plots were observed for these compounds. The detection limits of 4.5 and 3 microM were obtained for DMAET and DEAET respectively, with sensitivities of 1.18 and 1.37 nA microM(-1) cm(-2).