Eco-Friendly Fabrication of AgNP-Kaolinite Composite Using Persicaria odorata and Its Efficacy as Antibacterial Agent

This study presents the green synthesis of silver nanoparticle-incorporated kaolinite (K-AgNP-Kaol) using Persicaria odorata leaf extract as a natural reducing and capping agent. The biosynthesis was optimized by adjusting extract volume and reaction temperature, with optimal AgNP formation achieved at 0.6 mL of extract and 80°C, as indicated by a surface plasmon resonance (SPR) peak at 431 nm. Structural and morphological characterizations were conducted using Fourier Transform Infrared Spectroscopy (FTIR), Field Emission Scanning Electron Microscopy (FESEM), Transmission Electron Microscopy (TEM), and Energy Dispersive X-ray Spectroscopy (EDX), confirming the successful incorporation of AgNPs into the kaolinite matrix without compromising its structural integrity. Antibacterial activity was evaluated against Escherichia coli (Gram-negative), Staphylococcus aureus, and Cutibacterium acnes (both Gram-positive) through disc diffusion, minimum inhibitory concentration (MIC), and minimum bactericidal concentration (MBC) assays. The K-AgNP-Kaol composite exhibited inhibitory effects against all tested strains, with enhanced efficacy in deionized water compared to saline, likely due to reduced silver ions in the solution because of silver chloride (AgCl) formation in the saline solution. These findings highlight K-AgNP-Kaol as a promising, eco-friendly antibacterial material suitable for broad-spectrum applications.