Electrochemical studies on D96N bacteriorhodopsin and its application in the development of photosensors

The electrochemical studies on D96N bacteriorhodopsin (BR) are reported bas ed on chronoamperametry using immobilized BR on antimony-tin oxide (ATO) el ectrode. The absorption spectra of immobilized BR on ATO electrode shows an absorption peak at 570 nm suggesting the stability of immobilized BR on AT O. Chronoamperometry of the immobilized BR on ATO is studied using a one-co mpartment homemade electrochemical cell having the arrangement of device fo r external light exposure upon immobilized BR on ATO as working electrode, Ag/AgCl as reference electrode and a Pt foil as auxiliary electrode. The ch ronoamperometry is studied in the presence and absence of light following t wo approaches by controlling the duration of light exposure to immobilized BR: (i) exposure to external yellow light for 1 s and (ii) exposure to exte rnal light for 12-20 s. The variation of photocurrent with time under these conditions are reported and discussed. The approach (i) has been used for Che analysis of amine and ammonium compounds by measuring photocurrents in peak height mode. A good correlation between peak photocurrent and the conc entration of amine and ammonium compounds is recorded. The data on approach (ii) results in forward photocurrent in the presence of light and backward photocurrent when the light is shut off. The effects of lysine, arginine a nd ammonium nitrate on variations of forward and backward photocurrents are reported. The dependence of photocurrent on applied potential vs. Ag/AgCl is reported. The calibration curves for the analysis of ammonium ion and am ine compounds based on the measurement of photocurrent are reported. (C) 19 99 Elsevier Science S.A. All rights reserved.