Mokhtar Hjiri

Herein, sol–gel are used to synthesize pure and calcium‐doped ZnO (CZO). X‐ray diffraction shows that all samples have hexagonal wurtzite structure with a slight distortion of ZnO lattice and no extra secondary phases. The crystallite size increases after the addition of calcium from 31 to 34 nm. Photoluminescence shows the vanishment of the green emission band existed in the pure sample; in addition to the appearance of new peaks at 408, 448, 465, and 596 nm attributed to zinc interstitials (Zn i ), zinc vacancy (V Zn ), oxygen vacancy defect (V o ), and oxygen interstitial (O i ), respectively. The increase of crystallites size influences the efficacity of CZO sample against microbes. The different mechanisms to enhance the antibacterial activities are the release of Zn 2+ , reactive oxygen species production, and electrostatic interactions. Increasing the amount of CZO powder in dimethyl sulfoxide from 50 to 100 μg mL −1 leads to an increase of antibacterial activity of samples; and this is probably due to enhancement of number of interaction sites. Promising results are illustrated, which proves the potentiality of doping with Ca. The growth curves through optical density (OD 600 nm ) measurements of strains in CZO nanoparticles using serial fold dilution method indicated that strains viability decreases with increasing nanoparticles concentrations.