Unveiling the antibacterial potential of green-synthesized silver chloride and silver chromium nanoparticles from...

Green nanotechnology exhibits significant biomedical applications. In this study, green-synthesized silver/silver chloride (Ag/AgCl) and silver chromium (AgCr) nanoparticles (NPs), using Pelargonium graveolens leaf extracts (PLE), were characterized using X-ray diffraction (XRD), scanning electron microscopy (SEM) with energy dispersive X-ray spectroscopy (EDX), X-ray photoelectron spectroscopy (XPS), Fourier transform infrared spectroscopy (FTIR), ultraviolet-visible absorption spectroscopy (UV-Vis), and photoluminescence spectroscopy (PL). The study examined the antimicrobial activities of PLE and NPs on various bacterial isolates. PLE was effective against Gram-positive bacteria, Ag/AgCl-NPs against resistance strains, AgCr-NPs had a MIC of 125 µg/mL, and MBC was reported against K. pneumoniae. The bactericidal activity of PLE exhibited best effect at 24 h, while NPs killing activity start from the second hour to reach best effect at 24 h. Biofilm formation was decreased in a dose-dependent manner. This study used molecular docking to evaluate the binding interactions of NPs with key antibacterial target proteins in four pathogenic bacteria: A. baumannii, K. pneumoniae, Methicillin-resistant S. aureus (MRSA), and Methicillin-sensitive S. aureus (MSSA). The target proteins included Penicillin-Binding Proteins (PBPs) in A. baumannii (-10.30 kcal/mol for AgCl-NPs, -10.55 kcal/mol for AgCr-NPs), KPC-2 carbapenemase in K. pneumoniae (-13.00 kcal/mol for AgCl-NPs, -14.50 kcal/mol for AgCr-NPs), PBP2a in MRSA (-12.60 kcal/mol for AgCl-NPs, -12.80 kcal/mol for AgCr-NPs), and PBP3 in MSSA (-8.50 kcal/mol for AgCl-NPs, -9.50 kcal/mol for AgCr-NPs). The results showed extensive hydrogen bonds and hydrophobic interactions, suggesting AgCl and AgCr NPs could inhibit these enzymes, disrupt bacterial cell wall synthesis, and overcome resistance mechanisms.IMPORTANCEThe growth of antibiotic resistance poses a huge threat to global public health, prompting researchers to search for novel approaches to combat this rising issue. Nanotechnology, or the manipulation of materials at the nanoscale, has emerged as a possible route for combating antibiotic resistance. The green-synthesized Ag/AgCl-NPs and AgCr-NPs demonstrated high antibacterial activities against several bacterial isolates. This study indicates that Ag/AgCl-NPs and AgCr-NPs can serve as a promising therapy to treat bacterial infections, especially those that are resistant to drugs.