Abstract
The synthesis of nanoparticles by green approaches is gaining unique importance due to its low cost, biocompatibility, high productivity, and purity, and being environmentally friendly. Herein, biomass filtrate of Pseudomonas aeruginosa isolated from mangrove rhizosphere sediment was used for the biosynthesis of zinc oxide nanoparticles (ZnO-NPs). The bacterial isolate was identified based on morphological, physiological, and 16S rRNA. The bio-fabricated ZnO-NPs were characterized using color change, UV-visible spectroscopy, FT-IR, TEM, and XRD analyses. In the current study, spherical and crystalline nature ZnO-NPs were successfully formed at a maximum SPR (surface plasmon resonance) of 380 nm. The bioactivities of fabricated ZnO-NPs including antibacterial, anti-candida, and larvicidal efficacy were investigated. Data analysis showed that these bioactivities were concentration-dependent. The green-synthesized ZnO-NPs exhibited high efficacy against pathogenic Gram-positive bacteria (Staphylococcus aureus and Bacillus subtilis), Gram-negative bacteria (Escherichia coli and Pseudomonas aeruginosa), and unicellular fungi (Candida albicans) with inhibition zones of (12.33 ± 0.9 and 29.3 ± 0.3 mm), (19.3 ± 0.3 and 11.7 ± 0.3 mm), and (22.3 ± 0.3 mm), respectively, at 200 ppm. The MIC value was detected as 50 ppm for E. coli, B. subtilis, and C. albicans, and 200 ppm for S. aureus and P. aeruginosa with zones of inhibition ranging between 11.7 ± 0.3–14.6 ± 0.6 mm. Moreover, the biosynthesized ZnO-NPs showed high mortality for Culex pipiens with percentages of 100 ± 0.0% at 200 ppm after 24 h as compared with zinc acetate (44.3 ± 3.3%) at the same concentration and the same time.
Highlights
The color change was monitored by UV-Vis spectroscopy and showed maximum surface plasmon resonance at 380 nm, which was the characteristic peak of zinc oxide nanoparticles (ZnO-NPs)
ZnO-NPs was analyzed by Transmission Electron Microscopy (TEM), Fourier Transform Infrared (FT-IR), and X-ray diffraction (XRD) analysis
The FT-IR chart exhibited the role of various functional groups, for instance, C=O, O–H, NH, and SH thiol groups that exist in cell-free filtrate (CFF) in the reduction of Zn ion to form ZnO-NPs
Summary
The overuse of antibiotics and chemical pesticides led to the fast-growing resistant strains, as well as negative impacts on human health and the ecosystem. The linkage between nanotechnology and disease control science opens the way to limit the spread of these resistant strains [1,2]. Nanotechnology is a multidisciplinary field concerned with the manufacture, design, and application of nanoscale materials (1–100 nm). Due to the distinctive properties of nanomaterials, they have been applied in various fields such as materials science, chemistry, agriculture, medicine, physics, textile industry, and pharmaceuticals [3,4,5]. Contrary to a conventional concept, the nanoscale length affects the structure and total energy leading to changes in optical, thermal, mechanical, electronic, magnetic, chemical, and structural properties that characterize nanomaterial more than bulk materials [6,7]
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