IMPROVED PERFORMANCE OF CARBON-PASTE AMPEROMETRIC BIOSENSORS THROUGH THE INCORPORATION OF FUMED SILICA

The sensitivity and stability of carbon paste enzyme electrodes are gr eatly enhanced through the incorporation of fumed silica within the pa ste matrix. The improved performance is attributed to the adsorptive a nd electrocatalytic properties of the silica nanoparticles. The electr ocatalytic action results in a substantial lowering of the overvoltage for both the oxidation and reduction of the enzymatically liberated p eroxide species. Highly selective, low-potential, biosensing of glucos e is thus accomplished in the presence of coexisting acetaminophen, as corbic acid, or uric acid. The enhanced performance accrued from the p resence of silica is also illustrated for mediator (dimethyl ferrocene )-containing pastes. High enzymatic activity is maintained over prolon ged periods. The silica modification strategy provides an effective, f ast, and inexpensive route for immobilizing enzymes within carbon past e matrices.