Coimmobilization of dehydrogenases and their cofactors in electrochemical biosensors.

Maogen Zhang, Conor Mullens, Waldemar Gorski

Department of Chemistry, University of Texas at San Antonio, San Antonio, Texas 78249-0698, USA.

Analytical chemistry 2007 Mar 15

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Enzyme-based reagentless biosensors were developed using the model system of glucose dehydrogenase (GDH) and its nicotinamide adenine dinucleotide cofactor (NAD+). The biosensors were prepared following an approach similar to the concept of molecular imprinting. To this end, the N1-carboxymethyl-NAD+ species were covalently attached to polyamino-saccharide chains of chitosan (CHIT) and allowed to interact with GDH in an aqueous solution. The bioaffinity interactions between the NAD+ and GDH were secured by cross-linking the system with the glutaric dialdehyde (GDI)-modified CHIT. Electron conductive films of such CHIT-NAD+-GDH-GDI-CHIT macrocomplexes (MC) were prepared on glassy carbon (GC) electrodes by adding carbon nanotubes (CNT) and evaporating water. Electrochemical analysis of the GC/CNT-MC electrodes revealed that, in contrast to the oxidase-based electrodes, they acted as oxygen-independent reagentless biosensors. The application of Nafion to such biosensors predictably improved their selectivity and, unexpectedly, enhanced their sensitivity by an order of magnitude.

Citation

Maogen Zhang, Conor Mullens, Waldemar Gorski. Coimmobilization of dehydrogenases and their cofactors in electrochemical biosensors. Analytical chemistry. 2007 Mar 15;79(6):2446-50