Biosynthesis of Silver Nanoparticles from Lotus sanguineus: Photocatalytic, Antimicrobial, and Antibiofilm Activities with Molecular Docking Against Quorum-Sensing Proteins.

Industrial effluents containing toxic dyes, pathogenic microorganisms, and other hazardous contaminants pose a serious threat to environmental and public health, creating an urgent need for multifunctional materials capable of addressing both environmental pollution and microbial contamination. Silver nanoparticles (AgNPs) have attracted considerable attention because of their broad-spectrum antimicrobial and photocatalytic properties. In this study, AgNPs were biosynthesized for the first time using Lotus sanguineus, an endemic plant rich in bioactive phytochemicals, through an environmentally friendly green synthesis approach. To comprehensively evaluate their multifunctional performance, the photocatalytic, antimicrobial, and antibiofilm activities of the biosynthesized AgNPs were investigated, while molecular docking analysis was performed to elucidate their interactions with quorum-sensing-related proteins. AgNPs were characterized using UV-Vis spectroscopy, FTIR, XRD, DLS, and SEM. Under sunlight, AgNPs showed degradation efficiencies of 60.6% for methylene blue and 29.5% for eriochrome black T, indicating higher photocatalytic activity toward the cationic dye. Antimicrobial evaluation demonstrated notable antimicrobial activities against Escherichia coli, Bacillus cereus, Pseudomonas aeruginosa, and Staphylococcus aureus, with minimum inhibitory concentration (MIC) values ranging from 31.25 to 62.5 μg/mL and minimum bactericidal concentration (MBC) values between 125 and 250 μg/mL. Additionally, AgNPs exhibited a maximum inhibition of 94.5% at 62.5 μg/mL against Pseudomonas aeruginosa. Furthermore, molecular docking results revealed favorable binding affinities between the ligand and quorum-sensing transcriptional activator (LasR), N-terminal domain of anthranilate-CoA ligase (PqsA), P. aeruginosa aminopeptidase (PaAP), and peptidoglycan N-acetylglucosamine deacetylase (Pgd) proteins. Overall, the results highlighted the potential of AgNPs for pharmaceutical applications, prevention of bacterial surface colonization, and environmental remediation.