No 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.

The current study used a green technique that involves an aqueous leaf extract of Morus alba (mulberry) to synthesize silver nanoparticles (AgNPs) and assess their antibacterial and antiviral capabilities. The optical studies revealed a color shift from colorless -light yellowish to dark yellowish-brown as an indication of the reduction of silver metal ions & creation of silver nanoparticles and Ultraviolet-visible spectroscopy (UV-Vis) examination revealed a surface plasmon resonance (SPR) peak at 430 nm, indicating nano-silver (AgNPs) production. In addition, Fourier-transform infrared spectroscopy (FTIR) studies indicated that proteins, carbohydrates, and secondary metabolites may act as reducing and capping agents. While the Transmission electron microscopy (TEM) examination, revealed the produced nanoparticles were spherical, oval, and triangular with particle sizes ranging from 20 to 100 nm. Moreover, X-ray diffraction (XRD) measurements, show the crystalline structure of green synthesized (AgNPs) that are preferentially orientated along (1 1 1), (2 0 0), (220), and (311) planes. Furthermore, Silver nanoparticles had antibacterial action against both Gram-positive and Gram-negative bacteria, with the best results against Staphylococcus aureus ATCC 6538 at the highest concentration (conc.) of biosynthesized silver nanoparticles (400 µg/ml) with a maximum diameter of inhibition activity (24.33 mm), whereas the Minimal Inhibitory Concentration (MIC) was recorded at conc. (50 µg/ml) against both gram-positive and gram-negative bacteria, with the highest action against gram-negative bacteria Pseudomonas aeruginosa with a maximum diameter of inhibition activity (13.56 mm). In addition, silver nanoparticles showed promising antiviral activity against both Hepatitis B virus (HBV) and Hepatitis D virus (HDV) with maximum inhibition percent of 94.64 and 100 at conc. of 15.63 µg/ml of AgNPs for each virus respectively, and with minimal cytotoxic concentration (conc.) up to 99.5 percent and 90.66 percent viability on Human derived hepatoma (HepG2) cell line treated with silver nanoparticles at conc. of 7.81 µg/ml and 15.6 µg/ml respectively.