Eucalyptus camaldulensis gum as a green matrix to fabrication of zinc and silver nanoparticles: Characterization and novel prospects as antimicrobial and dye-degrading agents

Green biosynthesis of nanoparticles (NPs) has gained much significance due to costeffectiveness, time-efficiency, biocompatibility, and environmentally friendliness. Herein, we report the fabrication of zinc (ZnNPs) and silver nanoparticles (AgNPs) using Eucalyptus camaldulensis (EC) gum extract as a low-cost and green bio-matrix. The as-fabricated ECZnNPs and EC-AgNPs were comprehensively characterized by UV-visible spectroscopy, Fourier Transform infrared spectroscopy (FTIR), thermogravimetric analysis (TGA), X-Ray Diffraction (XRD), and scanning electron microscopy (SEM) techniques. Specific characteristic peaks of synthesized NPs were scrutinized through UV-visible and FTIR. The synthesized NPs revealed irregular shape and size with an increase in roughness of the surface. A delay in the rate of weight loss indicated the stable nature of EC-ZnNPs at high temperatures. Similarly, an increase in the crystallinity nature of EC-ZnNPs and EC-AgNPs was evidenced through XRD analysis. As compared to gum samples, the green fabricated EC-ZnNPs and EC-AgNPs performed an admirable inhibitory activity against a pathogenic bacterium (Escherichia coli) and fungal strain (Schizophyllum commune). Mutagenicity and cytotoxicity activities determined through Ames and haemolytic tests affirmed the nonmutagenic and non-toxic attributes of the gum samples and their derived EC-ZnNPs and EC-AgNPs. Finally, the EC-AgNPs and EC-ZnNPs showed a high photocatalytic potentiality towards the degradation of methylene blue dye under sunlight irradiation. In conclusion, the findings manifest excellent antimicrobial and dye degradation potentialities of gum based EC-ZnNPs and EC-AgNPs, representing its putative perspective as a novel nano antibiotic against pathogenic bacterial and fungal isolates, and for environmental mitigation. The present method is eco-friendly, clean and did not require any toxic/hazardous reductants. (C) 2020 The Authors. Published by Elsevier B.V.