Cow milk lactose inspired fabrication of zinc oxide (ZnO) nanorods for bio-applications

Abstract

Nanostructured materials with different architectures and sizes are pragmatically promising candidates for biological applications. Fabrication strategy greatly controls the morphological aspects of the nanoparticles (NPs) prepared from various precursors. Here, a simple lactose inspired technique for the fabrication of zinc oxide (ZnO) nanoparticles from zinc nitrate using cow milk has been established. The synthesis was carried out at five different calcination temperatures (65, 100, 300, 500, and 700 °C). The localized surface plasmon resonance behavior of ZnO was understood from UV–Vis spectroscopy. With the increase in calcination temperature, the absorption peak maxima showed bathochromic (red) shift. Fourier transform infrared (FTIR) transmission spectra identified characteristic Zn–O absorption band in the range 480–468 cm−1. The calcined products were mainly composed of Zn and O as understood from the energy dispersive X-ray spectroscopy (EDS) analysis. The thermal behavior of the product prepared at 65 °C was studied by theromogravimetric analysis (TGA). The crystallinity of ZnO nanoparticles was analyzed by X-ray powder diffraction (XRD) technique. The crystallite size of the fabricated ZnO nanoparticles was found to be 17.5–50.25 nm depending on the calcination temperatures (300–500 °C). A rod shape morphology of ZnO nanoparticle (width: 35 nm; length: 600 nm) was observed in the scanning electron microscopy (SEM) image. ZnO nanorods (NRs) showed promising antibacterial activity against gram-positive (Bacillus cereus) and gram-negative (Pseudomonas aeruginosa) bacteria. Besides, high cytotoxic effect against Hela and BHK-21 cells was also found. This study reports a green synthesis approach for the preparation of ZnO-NRs, which is expected to find widespread biological applications leading to the advancement of nanotechnology and nanoengineering.