ZnO nanoparticles and biocidal effect of nanostructured ZnO films on Escherichia coli

The biocidal effect of ZnO nanostructured films was studied using Escherichia coli ATCC 43897. The ZnO nanoparticles were synthesized in diethylene glycol by using zinc acetate forced hydrolysis. X-ray diffraction analysis confirmed the formation of single wurtzite-type ZnO phase with a crystallite size of 20.59 nm. Transmission electron microscopy observations revealed spherical-shaped particles in the nanoscale regime with a mean particle size of 21.96 nm. It was found that the addition of trioctylphosphine during synthesis favored much improved dispersion of ZnO nanoparticles, with smaller particle size; that is, 16.28 nm. Meanwhile, ZnO film grown onto glass substrate by spin-coating revealed single phase with the formation of aggregates (approximate to 700) having mushroom-like morphology formed of very fine particles in the nanoscale regime. The as-deposited nanostructured films exhibited a hydrophilic character. The classical bacteriological and electrochemical impedance spectroscopy measurements enabled the biocidal effect of ZnO nanostructured films with 94% inactivation efficiency after 90 min of contact time.