INVESTIGATION AND OPTIMIZATION OF REACTIVATION OF UREASE BIOSENSOR FOR HEAVY METALS INHIBITION ANALYSIS

Research was aimed at the optimization of the urease biosensor for analysis of heavy metals and determining the opportunities of its reactivation. A differential pair of gold interdigitated electrodes deposited on a ceramic substrate was used as the conductometric transducer. As a bioselective membrane served urease, coimmobilized with bovine serum albumin by glutaraldehyde cross-linking on the surface of conductometric transducer. 1.0 mM urea was selected as an optimal substrate concentration for the inhibition analysis of heavy metals. The biosensor was tested for its sensitivity to different heavy metals, the calibration curves were plotted. The proposed biosensor was shown to have high reproducibility of signals prior and after inhibition, the measurement error was less than 3%. It was proved a possibility of reactivation of the bioselective membrane after urease irreversible inhibition by heavy metals, using the ethylenediamine tetraacetic acid solution. The optimum conditions of reactivation, i.e. the dependence of its level on time and concentration of heavy metals, were determined. The additional stage, post-inhibition reactivation, was shown to increase significantly the selectivity of biosensor determination of heavy metals.