CHOLESTEROL SENSOR-BASED ON ELECTRODEPOSITION OF CATALYTIC PALLADIUM PARTICLES

A layer of palladium particles was electrodeposited on a glassy carbon electrode. The dispersed Pd particles resulted in a large decrease in overvoltage for the electrochemical oxidation of H2O2 down to +0.4 V vs. Ag/AgCl, based on which a new kind of cholesterol sensor was fabri cated. Cholesterol oxidase was immobilized on the Pd-dispersed electro de by cross-linking with glutaraldehyde and a layer of poly(o-phenylen ediamine) (PPD) film was electropolymerized on the enzyme layer. The s ensor shows a linear response in the concentration range 0.05-4.50 mmo l l-1 with a rapid response of less than 20 s. The polymer film can pr event interference from uric acid and ascorbic acid and also increases the thermal stability of the sensor. The sensor can be used for 200 a ssays without an obvious decrease in activity.