Zinc oxide nanoparticlc was deposited from zinc acetate solution that saturated by oxygen in potentiostat condition (—0.8 \1) The scanning electron microscopy (SEM) was shown the size of zinc oxide nanoparticle 50-100 urn. Due to the hirh surface area and good porosity of deposited zinc oxide, there is a considerable interesting in using ZnC) Nanostructure materials as a film-forming material. Repetitive cyclic voltammetry was used to immobilization of tuanine on glassy carbon-zinc oxide modified electrode. The immobilized guanine displays a pair of well defined stable and nearly reversible redox couple with f’ormal potentials (Jr) of 0 27V and irreversible oxidation peak at 0 72 V in p1-) phosphate huller solution. Cyclic voltammeiry and amperometry methods were used lbr investigation of’ clectrocatalyi ic activity of’ modified electrode. The Guanine— GC-ZnO modified electrode shown good elecirocatalytic activity toward L-cystein oxidation in wide pH range. Under optimized condition in amperometry method the concentration calibration range, detection limit and sensitivity were about, 0.5pM -
