A transducer based on enzyme-induced degradation of thin polymer films monitored by surface plasmon resonance

A novel transducer based on the dissolution of biodegradable polymer films as a direct result of enzymatic reaction has been developed. Three polymers were investigated for use in the transducer: a poly(ester amide), which is degraded by the proteolytic enzyme alpha -chymotrypsin; a dextran hydrogel , which is degraded by dextranase; and poly(trimethylene) succinate, which is degraded by a lipase. Degradation of the polymer films was monitored by surface plasmon resonance (SPR) and impedance measurements. SPR was shown t o be suitable for a greater variety of materials, since it does not require the polymer film to be electrically insulating, Rate of degradation was sh own to be directly related to enzyme concentration for each polymer/enzyme couple. The poly(ester amide)alpha -chymotrypsin couple proved to be the mo st sensitive, Degradation of the films was complete in less than 20 min for enzyme concentrations greater than 9 x 10(-9) mol dm(-3). Enzyme concentra tions as low as 4 x 10(-11) mol dm(-3) were detected in less than 30 min. T he transducer has great potential for the detection of enzyme concentration s as web as for use in immunosensing where the enzyme degrading the polymer would be the enzyme label.