Facile synthesis of Te-doped ZnO nanoparticles and their morphology-dependent antibacterial studies

The present study aims to carry out synthesis and characterization of Te-doped ZnO nanoparticles using an easy, low cost and solution-free thermo-mechanical method. The structural, morphological, optoelectronic characteristics of the as-prepared Te-doped ZnO NPs were analyzed by several techniques. From the FE-SEM studies, both pristine and Te-doped ZnO showed tube-shaped morphology when ground for 60 min. Remarkably, different grinding times caused the change in the shape of spherical ZnO NPs to tube-like ZnO. SEM images illustrate that spherical-like and hexagonal tube-like ZnO were prepared with grinding times 30 min and 60 min, respectively. XRD of Te-doped ZnO NPs (0.5wt%, 3wt%, 5wt%) revealed crystallite size of 10-20 nm. XPS results showed evidence for the binding energies of ZnO and Te. Disk diffusion assay showed that Te-doped ZnO NPs demonstrated good antibacterial activity against E. coli DH5 alpha cells compared with pristine ZnO NPs. The mechanism of antibacterial activity of ZnO NPs was due to the generation of reactive oxygen species (ROS), causing lipid peroxidation of the bacterial cell wall and resulting in the leakage of cellular contents and cell death. The photoexcited electrons were trapped by the oxygen vacancies and prevented the interaction between oxygen available on the exterior of the ZnO NPs and photoexcited electrons. This results in reducing the amount of ROS generation and subsequently lower antibacterial activity.