Antimicrobial Agent Based on Ca‐Doped ZnO Nanopowders

Abstract

Sol‐gel has been used to synthesize pure and calcium doped ZnO (CZO) nanopowders under supercritical dry conditions of ethanol and characterized by scanning electron microscopy (SEM), transmission electron microscopy (TEM), X‐ray diffraction (XRD), Fourier transform infrared (FTIR) spectroscopy and Photoluminescence (PL). XRD showed that undoped and Ca‐doped ZnO samples have a hexagonal wurtzite structure with a slight distortion of ZnO lattice and no extra secondary phases, suggesting the substitution of Ca ions in the ZnO structure. The average crystallite size is increased after the addition of Ca dopant from 31 to 34 nm. PL spectroscopy showed the removal of the green emission band that existed in the pure sample; in addition to the appearance of new peaks at 408, 448, 465 and 596 nm attributed to zinc interstitials (Zni), zinc vacancy (VZn), oxygen vacancy defect (Vo) and oxygen interstitial (Oi), respectively. Antibacterial tests are performed to check the efficacity of CZO material against gram‐positive, gram‐negative bacteria and fungi. The increase in crystallites size influenced the efficacity of the CZO sample against microbes. The different mechanisms that are believed to enhance the antibacterial activities are the release of Zn2+, ROS production and electrostatic interactions. Increasing the amount of CZO powder in DMSO from 50 µg/ml to 100 µg/ml led to an increase in the antibacterial activity of the nanomaterial, and this is potentially due to the enhancement of several interaction sites. Promising results have been illustrated, which proves the potentiality of doping with this element. The growth curves through optical density (OD600 nm) measurements of the pathogenic strains in Ca‐ZnO nanoparticles using the serial fold dilution method indicated that the strains’ viability decreases with increasing nanoparticle concentrations.This article is protected by copyright. All rights reserved.

Ammonia gas sensors based on undoped and Ca-doped ZnO nanoparticles

“…This behavior can be explained in terms of electronic defects such as oxygen vacancies (V O ) and zinc interstitials (Zn i ), which are created after the addition of Ca ions in the ZnO network, as cited by Saeedi and his colleagues. 42 Zn i and V O acted as donor defects, leading to an increase in the concentration of free electrons. 43 These free electrons take part in the interaction between the sensing layer and ammonia molecules by reducing C1ZO sensing layer resistance and then the response increases.…”