Electrochemical reaction of fructose dehydrogenase on carbon cryogel electrodes with controlled pore sizes

Carbon cryogels (CCG) with controlled porous size were developed for enzyme electrode. CCGs were prepared by sol–gel polycondensation of resorcinol and formaldehyde using CO32- as a catalyst. The average pore radius range from 5 to 40 nm was controlled by changing the mole ratio of resorcinol to the catalyst. Fructose dehydrogenase adsorbed on a CCG electrode exhibited large catalytic currents for fructose oxidation without redox mediators. The catalytic current depended on the pore size. The catalytic current density was quite low when the pore size of CCG was small compared with the size of FDH. On the other hand, the wider pore resulted in higher catalytic current density was observed under the experimental conditions. It is assumed that caged enzymes embedded in the carbon mesopore are apt to communicate with the electrode directly.