Microwave-assisted green synthesis of Desmodium triquetrum-mediated silver nanoparticles: enhanced antibacterial, antibiofilm, and cytotoxicity activities against human breast cancer cell lines

Green synthesis of nanoparticles using plant extracts has attracted great interest due to it being a low cost and environment-friendly method. In this study, a simple, fast, and green process for the synthesis of silver nanoparticles by microwave irradiation using aqueous Desmodium triquetrum extract (DTE) was investigated. The plant extract contained polyphenols that were observed by liquid chromatography-tandem mass spectrometry (LCMS/MS) analysis. The biosynthesized silver nanoparticles showed a maximum peak at 430 nm in the UV-Vis spectrum. The hydrodynamic size (Z-average size), polydispersity index (PI), and zeta potential of the AgNPs were assessed by dynamic light scattering (DLS) analysis showing the values of 88.8 nm, 0.355, and -27.4 mV, respectively. Spherical silver nanoparticles were observed in the FE-SEM image with an average diameter of 21.63 +/- 4.85 nm. The X-ray diffraction (XRD) result showed a crystalline face-centred cubic structure of the silver nanoparticles. The FTIR spectra revealed phytochemicals involved in the synthesis of AgNPs. Determination of the antibacterial and antibiofilm activities of the AgNPs was conducted against four pathogens, namely B. subitilis, P. aeruginosa, E. coli and K. pneumoniae. These AgNPs exhibited strong antibacterial activity against B. subitilis (MIC value of 3.9 mu g mL(-1)) and P. aeruginosa (7.8 mu g mL(-1)) and moderate antibacterial activity against E. coli (15.1 mu g mL(-1)) and K. pneumoniae (31.25 mu g mL(-1)). In addition, the silver nanoparticles showed potent inhibition of biofilm formation at supra-MIC (2 MIC) for all tested pathogens and significant cytotoxicity against human breast cancer cell lines (MCF-7). These results suggested that Desmodium triquetrum could be an effective natural resource for the synthesis of silver nanoparticles, which have possible applications as antibacterial, antibiofilm, and cytotoxic agents against breast cancer cell lines.