Substantial effect of Cr doping on the antimicrobial activity of ZnO nanoparticles prepared by ultrasonication process

Highlights: • The Cr successfully doped on ZnO NPs. • The Cr doped ZnO NPs enhanced the antimicrobial activity against various bacteria and fungi at lowest concentration. • Intracellular damage and morphological alteration was successfully confirmed by Cr doped ZnO NPs treated pathogens. This study was involved to investigate the effect of Cr incorporation on various physic-chemical properties of ZnO nanopowder that including structural, morphological, optical and antibacterial. The synthesized powder reveals wurtzite hexagonal structure with decreased crystallite size from X-ray diffraction analysis. The scanning electron microscope (SEM) result confirmed that the formation of hexagonal shaped particles was observed on Cr doped ZnO nanoparticles. The presence of vibration band in the range of 450–600 cm⁻¹ was confirm, the successful formation of Zn-O bond in bare and Cr doped ZnO nanoparticles. The decreased reflectance and red shift in the UV–vis diffused reflectance spectra was confirmed the decreased band gap energy. The antibacterial investigation of the nanopowder reveals, the higher zone of inhibition, membrane damage and intracellular alterations were observed against K. pneumoniae and C. albicans compared with other microorganisms. Thus, the result was suggested that the Cr doped ZnO nanoparticle as a promising candidate material for the development of new antibiotics against various bacteria.