Microwave-assisted green synthesis of AM-ZnO NP from Atalantia monophylla leaf extract, opto-structural property characterization and biomedical applications

Metal and metal oxide nanoparticles are significant in terms of their use in various medical, photo-catalytic, semiconducting devices and many more promising industrial applications. AM-ZnO NP was sustainably synthesized from Atalantia monophylla aqueous leaf extract to avoid the pros and cons of the chemical synthesis of metallic nanoparticles under the theme of green chemistry. Opto-structural properties of AM-ZnO NP have been characterized by UV–Vis spectrophotometer, FTIR spectral band, and Photoluminescence to optimize the optical properties while XRD, SEM, HR-TEM, and EDX have been used to optimize structural properties. Temperature dependant stability of AM-ZnO NP was evaluated through Thermal analysis (TGA, DSC and DTG). However, average hydrodynamic diameter (192 nm), poly-dispersity index (0.150) and Zeta potential values (− 8.66 mV) confirmed the stability of nanoparticles in double-distilled water as well. The successful application of AM-ZnO NP was proved by the formation of an active zone of inhibition around the disc where the diffusion method was used against both gram-positive and gram-negative strains at 200 µg/ml. Significant antioxidant activity by AM-ZnO NP has been noticed using the in-vitro DPPH (IC 50 —78.49 µg/ml) and ABTS (IC 50 —88.46 µg/ml) assay compared to antioxidant activity shown by A. monophylla leaf extract and Gallic acid standard. AM-ZnO NP presented biocompatible properties with normal (immortal) HEK 293 cells (IC 50 —63.29 µg/ml) but demonstrated active inhibitory ion properties against HeLa cell lines (IC 50 —51.93 µg/ml). Green synthesis of AM-ZnO NP using bio-resource as template offers a better option in biomedical applications.