title: Coimmobilization of dehydrogenases and their cofactors in electrochemical biosensors.
abstract: 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.
authors.affiliation: Department of Chemistry, University of Texas at San Antonio, San Antonio, Texas 78249-0698, USA.
authors.forename: Maogen
authors.initials: M
authors.lastname: Zhang
authors.forename: Conor
authors.initials: C
authors.lastname: Mullens
authors.forename: Waldemar
authors.initials: W
authors.lastname: Gorski
mesh_terms: D015374:Biosensing Techniques / Q000379:methods*; D048271:Chitosan / Q000378:metabolism; D004563:Electrochemistry; D004566:Electrodes; D004800:Enzymes, Immobilized / Q000378:metabolism*; D005947:Glucose / Q000032:analysis / Q000378:metabolism; D013058:Mass Spectrometry; D015394:Molecular Structure; D009243:NAD / Q000378:metabolism*; D010088:Oxidoreductases / Q000378:metabolism*; D012680:Sensitivity and Specificity
chemical_list: D004800:Enzymes, Immobilized; D009243:NAD; D048271:Chitosan; D010088:Oxidoreductases; D005947:Glucose