MONITORING OF ENZYMATIC-ACTIVITY AND QUANTITATIVE MEASUREMENTS OF SUBSTRATES BY MEANS OF A NEWLY DESIGNED SILICON-BASED POTENTIOMETRIC SENSOR

By utilizing a modified light addressable potentiometric sensor (LAPS) technology, we designed a device for investigation of enzymatic reactions. The sensing principle is the detection of pH variations due to the catalyzed reaction. The system is divided into two main parts, a reaction chamber and a measuring chamber which contains the silicon transducer. By monitoring the H+ production, we obtain information either about the substrate concentration (by using a fixed amount of enzyme) or about the enzyme concentration and activity (if the initial substrate concentrations are constant). Theoretical analysis and modeling were carried out in order to optimize the performance of the system and to predict and explain the experimental curves with alcohol dehydrogenase. By using this set-up it was possible to detect enzyme concentrations down to the 10(-10) M range.