CHEMICAL CROSS-LINKING OF A REDOX MEDIATOR THIONIN FOR ELECTROCATALYTIC OXIDATION OF REDUCED BETA-NICOTINAMIDE ADENINE-DINUCLEOTIDE

Thionin, a redox mediator that has been used to study the electrochemical behavior of reduced beta-nicotinamide adenine dinucleotide (NADH), was chemically cross-linked on the surface of a spectroscopic graphite electrode by using a triisocyanate cross-linking agent. The electrodes modified in this manner had a purple film with an additional reversible redox couple at E-degrees' of +73 mV vs. Ag/AgCl compared to uncross-linked thionin. The thionin modified electrode mediated oxidation of NADH with response to NADH between 7.0 x 10(-7) to 1.8 x 10(-3) M, a sensitivity of 113-mu-A/cm2/mM, and a detection limit of 0.5-mu-M.