Synergistic effect of coconut milk and water on synthesizing zinc oxide nanoparticles and its antibacterial properties

Abstract

Utilizing natural extract to prepare nanoparticles has grabbed the attention of researchers’ worldwide due to its magnificent physicochemical properties. In the present work, zinc oxide nanoparticles (ZnO NPs) were produced with the assistance of phytochemicals found in two different natural extract: coconut milk and coconut water. The structure, optical, morphology, and biological performance of the prepared particles were examined and analyzed. X-ray diffraction pattern clearly infers the presence of crystalline natured ZnO NPs with hexagonal wurtzite structure. The average crystallite size is calculated as 25.5 and 11.3 nm for ZnO NPs using coconut milk and water respectively. Furthermore, Fourier transform infrared spectroscopy shows the characteristic peaks from 400 to 900 cm−1 corresponds to stretching band of ZnO. Photoluminescence spectroscopic techniques were employed to analyze the types of defects present in the synthesized nanoparticles. The optical property of the prepared NPs was examined from ultraviolet-visible spectrum and its bandgap obtained from Tauc plot found to reduce from 3.07 to 2.78 eV due to recombination of electron-hole pair. For both ZnO NPs, scanning electron microscopic analysis revealed the formation of spherical shape particles measures from 20 to 80 nm without any agglomeration. The formation of rod-shaped particles was identified from transmission electron microscopic images for coconut water mediated ZnO NPs. The presence of Zn and O revealed from XPS spectrum. Both ZnO NPs were tested for antibacterial activity against Staphylococcus aureus,Streptococcus pneumonia, Klebsiella pneumoniae, and Escherichia coli at different concentrations using disc diffusion method. The NPs produced using coconut water exhibit an IC50 of 47.99 over coconut milk (113.5) from the anti-inflammation investigation. According to these results, coconut water-derived ZnO NPs may be a promising nanomaterial with the potential to be used in cutting-edge medical procedures. © 2023, The Author(s), under exclusive licence to Springer-Verlag GmbH Germany, part of Springer Nature.