Biosensor based on enzyme-catalysed degradation of thin polymer films

A biosensor based on the enzyme-catalysed dissolution of biodegradable poly mer films has been developed. Three polymer-enzyme systems were investigate d for use in the sensor: a poly(ester amide), which is degraded by the prot eolytic enzyme alpha -chymotrypsin; a dextran hydrogel, which is degraded b y dextranase; and poly(trimethylene) succinate, which is degraded by a lipa se. Dissolution of the polymer films was monitored by Surface Plasmon Reson ance (SPR). The rate of degradation was directly related to enzyme concentr ation for each polymer/enzyme couple. The poly(ester amide)/alpha -chymotry psin couple proved to be the most sensitive over a concentration range from 4 x 10(-11) to 4 x 10(-7) mol l(-1) of enzyme. The rate of degradation was shown to be independent of the thickness of the poly(ester amide) films. T he dextran hydrogel/dextranase couple was less sensitive than the poly(este r amide)/alpha -chymotrypsin couple but showed greater degradation rates at low enzyme concentrations. Enzyme concentrations as low as 2 x 10(-11) mol l(-1) were detected in less than 20 min. Potential fields of application o f such a sensor system are the detection of enzyme concentrations and the c onstruction of disposable enzyme based immunosensors, which employ the poly mer-degrading enzyme as an enzyme label. (C) 2001 Elsevier Science B.V. All rights reserved.