Critical Effect of Polyelectrolytes on the Electrochemical Response of Dehydrogenases Entrapped in Sol-Gel Thin Films

The influence of polyelectrolyte (PE) additives on the sol-gel encapsulation of dehydrogenases has been evaluated using D-sorbitol dehydrogenase (DSDH) as a model enzyme. Thin sol-gel films were prepared on glassy carbon electrodes (GCE), which were then evaluated with respect to the electrochemical detection of D -sorbitol. DSDH encapsulation in pure silica thin films resulted in undetectable electrochemical signal. Adding positively-charged PE that contributes to stabilize the negatively-charged DSDH in the biocomposite film led to much faster and higher response of DSDH to its substrate, as shown by the significant improvement in bioelectrochemical detection of NADH produced during the oxidation of D-sorbitol.