Solid-phase optoelectronic sensors for biochemical analysis.

Simple solid-phase optoelectronic sensors for penicillin, urea, and glucose are described. Triphenylmethane dyes such as bromcresol green and bromthymol blue were derivatized with glutathione and co-immobilized with appropriate enzymes to a transparent membrane sandwiched between a red-light-emitting diode and a silicon photodiode with integral amplifier. In the presence of the corresponding substrates, catalytic action in the enzyme-dye membrane perturbs the local pH and causes characteristic color changes in the membrane which are monitored as a rise or fall in the output voltage of the detector system. With enzymes such as penicillinase, urease, and glucose oxidase, the response of the optoelectronic sensors is extremely reproducible over the concentration range 0-10 mM penicillin G, urea, or D-glucose, respectively. This report describes the construction and operation of these simple, inexpensive, and reagentless optoelectronic sensors.