Eco-Friendly Bio-Fabrication of Silver Nanoparticles by Cenchrus biflorus (Roxb.): Their Characterization and Biological Activity Exploration

Silver nanoparticles (AgNP) have extensive and exceptional applications in a variety of sectors, particularly medicine. We developed an eco-friendly method to synthesize AgNPs from an extract of Cenchrus biflorus. CB extract was used to make AgNPs using an environmentally friendly process. UV–Vis. spectroscopy was used to obtain an absorbance of 1.9 and a prominent peak at 440 nm. Fourier-transform infrared spectroscopy revealed some peaks, indicating the presence of distinct phytochemicals that produce AgNPs. AgNPs ~20 nm in diameter and spherical in shape were identified via scanning electron microscopy. The desired bands at 2θ values of 32.34^o, 38.16^o, and 46.3^o obtained using X-ray diffraction verified the crystal structure of the AgNPs with a size of 14.59 nm. AgNPs and the plant extract exhibited strong antioxidant activity against 2,2-diphenyl-1-picrylhydrazyl, H₂O₂, and ABTS (2,2-azino-bis-3-ethylbenzothiazoline-6-sulphonic acid) with maximum Scavenging activities of 82.2% and 75.5%, 72.2% and 65.5%, and 66.2% and 53.5%, respectively. AgNPs and the plant extract also exhibited antimicrobial activity against certain fungal and bacterial strains with a maximum inhibition of 40.2 ± 0.04 and 35.5 ± 0.9 mm against Aspergillus niger, 37.2 ± 0.08 and 31.5 ± 0.9 mm against Aspergillus flavus, 13 ± 0.9 and 10.5 ± 0.5 mm against methicillin-resistant Staphylococcus aureus, 14.25 ± 0.09 and 11.5 ± 0.9 mm against Streptococcus pyogens, 11 ± 0.9 and 10 ± 0.8 mm against Escherichia coli, and 12 ± 0.9 and 11 ± 0.8 mm against Klebsiella pneumoniae. AgNPs and the plant extract possessed good antidiabetic properties with a maximum inhibition of 65.2% and 53.5%, respectively. Both the plant extract and AgNPs revealed a type of inhibition that competes because their Vmax values remained constant as Km values increased. The anti-Alzheimer property of AgNPs and the plant extract exhibited a maximum inhibition of 88.6% and 62.2%, and AgNPs and the plant extract confirmed an aspect of noncompetitive inhibition due to which Vmax decreased and Km remained unchanged as the AgNP and plant extract concentrations increased.