Abstract
The biogenic synthesis of silver nanoparticles (AgNPs) has a wide range of applications in the pharmaceutical industry. Here, we synthesized AgNPs using the aqueous flower extract of Bauhinia tomentosa Linn. Formation of AgNPs was observed using ultraviolet-visible light spectrophotometry at different time intervals. Maximum absorption was observed after 4 h at 420 nm due to the reduction of Ag+ to Ag0. The stabilizing activity of functional groups was identified by Fourier-transform infrared spectroscopy. Size and surface morphology were also analyzed using scanning electron microscopy. The present study revealed the AgNPs were spherical in form with a diameter of 32 nm. The face-centered cubic structure of AgNPs was indexed using X-ray powder diffraction with peaks at 2θ = 37°, 49°, 63°, and 76° (corresponding to the planes of silver 111, 200, 220, 311), respectively. Energy-dispersive X-ray spectroscopy revealed that pure reduced silver (Ag0) was the major constituent (59.08%). Antimicrobial analyses showed that the biosynthesized AgNPs possess increased antibacterial activity (against Staphylococcus aureus (Gram-positive) and Escherichia coli (Gram-negative), with larger zone formation against S. aureus (9.25 mm) compared with that of E. coli (6.75 mm)) and antifungal activity (against Aspergillus flavus and Candida albican (with superior inhibition against A. flavus (zone of inhibition: 7 mm) compared with C. albicans (zone of inhibition: 5.75 mm)). Inhibition of 2,2-diphenyl-1-picrylhydrazyl (DPPH) radical scavenging activity was found to be dose-dependent with half-maximal inhibitory concentration (IC50) values of 56.77 μg/mL and 43.03 μg/mL for AgNPs and ascorbic acid (control), respectively, thus confirming that silver nanoparticles have greater antioxidant activity than ascorbic acid. Molecular docking was used to determine the mode of antimicrobial interaction of our biosynthesized B. tomentosa Linn flower-powder extract-derived AgNPs. The biogenic AgNPs preferred hydrophobic contacts to inhibit bacterial and fungal sustainability with reducing antioxidant properties, suggesting that biogenic AgNPs can serve as effective medicinal agents.
Highlights
Nanoparticles are structures with dimensions ranging from approximately 1 to 100 nm that exhibit significantly different physical and chemical properties when compared with their larger counterparts [6,7]
AgNPs could mediate the antimicrobial activity by producing reactive oxygen species and free radicals causing cell wall damage, lipid peroxidation, protein denaturation, and nucleic acid and proton pump damage [4,23]
Ground B. tomentosa Linn flower powder (20 g) was soaked in distilled water for 24 h with mild shaking at room temperature, boiled for 10 min, filtered using Whatman grade 1 filter paper (Sigma-Aldrich), and concentrated by a rotary vacuum evaporator at 20 ◦ C
Summary
Resistance to antibiotics and a wide variety of microorganisms in the public health system has become a major obstacle, and almost every single variant of microorganisms has Antioxidants 2021, 10, 1959. Over the past 10 to 20 years, metal nanoparticles, and AgNPs in particular, have attracted attention due to their versatility and broad range of industrial and biomedical applications [8,9,10,11]. Potential uses include antimicrobial (antibacterial, antifungal, and antiviral) agents [12,13,14,15,16,17], biomedical device coatings, drug-delivery carriers, and imaging probes for diagnostic and optoelectronic applications [18,19,20,21,22]. Biological synthetic pathways based on microorganisms or plant extracts have been widely explored for the production of
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