Amperometric biosensor with a composite membrane of sol-gel derived enzyme film and electrochemically generated poly(1,2-diaminobenzene) film.

A sol-gel silicate-based biosensor for glucose was made by utilizing a composite membrane of sol-gel enzyme film and electrochemically generated poly(1,2-diaminobenzene) film to improve the selectivity of the sol-gel enzyme sensors. The stability of the sensor was improved by exposing the enzyme layer to glutaraldehyde vapor. The glucose sensor responded rapidly (ca. 15 s) to glucose at 0.6 V (versus Ag/AgCl), without any interferences from electroactive species such as L-ascorbate and urate below 0.2 mM. Reliable results were obtained in the assays of glucose in controlled human sera, with both the steady-state and flow-injection measurements. Subsequently, the same sol-gel procedure was applied to the preparation of the sensors for galactose and cholesterol. The galactose and cholesterol sensors responded rapidly to galactose and cholesterol, respectively, although the sensitivity of these sensors was inferior to that of glucose sensor.