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Sunlight driven Mnn+-ZnO (n = 2, 4 and 7) nanohybrids were prepared via impregnation method using different metal precursors of variable oxidation state. Dynamic light scattering (DLS) spectra showed that the average hydrodynamic size decreased when precursor of higher Mn oxidation state was used. Moreover, the structural analysis revealed that Mn nanoparticles (5–10 nm, d = 0.13 nm) dispersed over ZnO support (20–30 nm, d = 0.39 nm) while KMnO4 was added for impregnation purpose. Interestingly, the co-catalyst (Mn) was loaded in + 2, +4 and + 7 oxidation state when MnSO4.H2O, MnO2 and KMnO4 respectively utilized for loading over ZnO surface, confirmed from X-ray photon spectroscopy. The potential of prepared nanocomposites were investigated for methylene blue (MB) degradation, an organic pollutant and it was observed that oxidation state of the co-catalyst largely influenced the photoactive-response of nanocomposites. Notably, Mn7+-ZnO degraded MB (98%) nearly 3.3 times higher as compared to bare ZnO and also higher than Mn4+-ZnO (91%) and Mn2+-ZnO (83%). The metal nanoparticles played a dual role in the photo-oxidative reaction by sensitizing the nanomaterial in the sunlight and suppressing the recombination rate of electrons-holes to enhance the reaction efficiency. [ABSTRACT FROM AUTHOR]

The present study portrays, a low-cost, environmentally benign, and green route synthesis of Mangifera indica leaf extract mediated silver nanoparticles (MI:AgNPs). MI:AgNPs were characterized using analytical techniques such as X-ray diffraction (XRD), Fourier Transform Infrared Spectroscopy (FTIR), UV–Visible spectroscopy, Transmission Electron Microscopy (TEM). The structural characterization revealed that MI:AgNPs exhibited face centered cubic crystallinity with space group F m 3 ¯ m without any traces of impurities and secondary phases. FTIR spectra confirmed the presence of phytochemicals (such as alkaloids, polyphenols, flavonoids, etc.) present in leaf extract, which serves as reducing, stabilizing and capping agent. UV–Vis spectra showed a sharp absorption peak in the UV region belonging to leaf extract and a hump in the visible region (~ 404 nm) attributed to the formation of AgNPs. TEM micrograph showed pseudo-spherical particles with average diameter of 18.2 ± 0.12 nm. MI:AgNPs showed enhanced photocatalytic activity against Methylene Blue (MB) dye under UV radiation. Cytotoxic activity was carried out on cervical cancer cell line (HeLa) at different concentrations of MI:AgNPs, which displayed potent anti-cancerous potential and illustrated the efficacy of MI:AgNPs with a low IC50 value 83.85 ± 9.63 µg/mL. The low-cost synthesis and effective cytotoxic potential of MI:AgNPs can make them an attractive choice for biomedical application. [ABSTRACT FROM AUTHOR]