Growth inhibition of Escherichia coli by zinc molybdate with different crystalline structures

Zinc molybdate powders were synthesized by hydrothermal methods using different salt precursors, and in the presence (or absence) of citric acid as surfactant. As a function of precursors, synthesis conditions and post-synthesis annealing, powders with various sizes (from tens of nm up to 10 mu m) and different crystallographic structures (alpha, beta, hydrated, and nonhydrated mixed alpha- and beta-phases) were obtained. Bactericidal properties of suspensions containing different concentrations (1, 5, and 10 mM) of powders of alpha, beta, and mixed alpha/beta ZnMoO4 phases were tested against Escherichia coli. Optical density measurements and the results obtained from the observation of cultures growth on agar petri dishes clearly showed that ZnMoO4 possesses antibacterial properties. The antibacterial efficiency was dependent on the concentration of powders in suspension, as well as on the crystalline structure in relation to the crystals size/surface structuring. The intrinsic semiconducting properties of this material, together with the defect states present in the bandgap which hindered the recombination of electronhole pairs produced under visible light, as well as electronic transitions were factors proposed as being responsible for the observed antibacterial activity by the creation of reactive oxygen species and hydrogen peroxide. [GRAPHICS] (C) 2016 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim