Platinum Islands on SAMs as Template for Enzyme-Catalyzed Glucose Oxidation

Abstract

Multilayer electrodes for highly enantioselective sugar conversion are obtained by using monoatomically high platinum islands as pattern for further electrode modification with pyranose-2-oxidase (P2Ox). We describe this kind of electrode for the glucose oxidation. The reaction is monitored via the H2O2 production by the enzyme as side product. As first layer, a self-assembled monolayer (SAM) is arranged on the Au(111) surface via dip coating in a solution of 4-mercaptopyridine. On top of the SAM, a controlled distribution of platinum islands is obtained by a combination of electroless and electrochemical deposition using a solution of K2PtCl4. The platinum islands have a diameter of about 6 nm. Thereon, poly(allylamine hydrochloride) (PAA) obtained by dip coating provides a linker for immobilization of the enzyme pyranose-2-oxidase. Our assumption is that only one enzyme molecule is bound to one platinum island. This well ordered surface structure is probably the reason for the very high conversion efficiency.