Construction of Nano Coenzyme and Enzyme Multilayer Film on Gold Electrode by Self-assembly Method

A ferrocene labeled high molecular weight coenzyme derivative (PEI-Fc-NAD) was prepared by attaching both ferrocene (Fc) and coenzyme (nicotinamide adenine dinucleotide, NAD(+)) to the backbone of poly(ethylenimine) (PEI). A NAD-dependent glucose-6-phosphate dehydrogenase (G6PDH) was used with PEI-Fc-NAD to fabricate a multilayer film on gold electrode by layer-by-layer self-assembly method. The G6PDH/PEI-Fc-NAD multilayer film was characterized by atom force microscope and electrochemical experiment, which proved that a nano structure thin film was immobilized by the LBL technique. The modified electrode showed the current response to glucose-6-phosphate in the absence of free coenzyme, and kept about 85% response after storage in buffer for 2 month.