Urease immobilized piezoelectric quartz crystal for Urea conversion

In this study, the immobilization of the enzyme urease on the surface of the quartz crystal was reported. The layer growth on silver electrode resonator was monitored with QCM and the catalytic activity of the enzyme layer was studied with UV-Vis spectroscopy at 255 nm by the detection of unconverted urea quantity in pH 7.4 phosphate buffer. Urease immobilization efficiency was tested with two initial urease concentrations, 0.02 and 0.2 mg/ml, respectively. The crystals of various urease immobilized amount was treated with urea solutions of 0.0025-0.02 mg/ml. The best conversion results were obtained for the crystal that treated with 0.02 mg/mL initial urease solution with 65 % conversion for 8.33x$10^ {-5}$ M urea concentrations and less than this value. In case of 0.2 mg/ml urease immobilization, more than 52 % of urea was converted when exposed to 1.6x$10^ {-4}$ M urea.