Abstract
Immobilization and direct electrochemistry of proteins and enzymes can provide a good model for mechanistic studies of their electron transfer activity in biological systems. Moreover, achieving direct electron exchange between redox proteins or enzymes and electrodes simplifies third generation biosensors, enzymatic bioreactors and biomedical devices by removing the requirement of chemical mediators, and thus has a great significance. We have immobilized enzymes and redox proteins, such as glucose oxidase (GOx), alcohol dehydrogenase (ADH), horseradish peroxidase (HRP), and catalase (CAT) on the surface of the modified electrode. The matrixes which we prepared for the enzyme immobilization are gelatin-Multiwalled carbon nanotube (GCNT), Bismuth oxide nanoparticles-MWCNT composite, didodecyldimethylammonium bromide (DDAB) present on nafion dispersed multiwalled carbon nanotubes (MWCNTs-NF) and biocomposite of Toluidine blue O with adsorbed alcohol dehydrogenase (ADH). The surface morphology of the enzyme immobilized modified electrode were characterized by Scanning electron microscopy and atomic force microscopy. GOx/GCNT, NF/HRP/Bi2O3-MWCNT, MWCNTs-NF-(DDAB/CAT) and ADH/TBO/NF films exhibited a wide linear response from 6.30 to 20.09 mM (glucose), 8.34-28.88 mM (H2O2), 0.5 to 1.2 mM (H2O2) and 283-856 mM ethanol respectively. These films showed sensitivity of 2.47 mu AmM-1 cm(-2), 26.54 mu AmM-1 cm(-2), 101.74 mu AmM-1 cm(-2) and 7.91 mu AM(-1) cm(-2) respectively. All the developed sensors show good stability with appreciable sensitivity, selectivity and wide linear range.