Chitosan-Coated Silver Nanocomposites: Biosynthesis, Mechanical Properties, and Ag+ Release in Liquid and Biofilm Forms

This study explores the biosynthesis, characterization, and evaluation of silver nanoparticles coated with chitosan (AgChNPs) for liquid nanocomposite and biofilm formation in integrated pest management (IPM). AgChNPs were synthesized using <i>Galega officinalis</i> leaf extract as a reducing agent, with varying chitosan concentrations (0.5%, 1%, and 2%) and pH levels (3, 4, and 5). Synthesis was optimized based on nanoparticle size, stability, and polydispersity index (PDI) over 21 days. Biofilms incorporating AgChNPs were analyzed for chemical, physical, mechanical, and thermal properties via Ultraviolet-visible spectroscopy (UV-vis), Dynamic Light Scattering (DLS), Zeta Potential Analysis, Fourier Transform Infrared Spectroscopy (FTIR), X-Ray Diffraction (XRD), Transmission Electron Microscopy with Energy Dispersive X-ray Spectroscopy (TEM-EDX), and Inductively Coupled Plasma Optical Emission Spectroscopy (ICP-OES) to quantify silver ionization. TEM confirmed spherical nanoparticles (5.54-61.46 nm), and FTIR validated <i>G. officinalis</i> functionalization on chitosan. AgChNPs with 1% chitosan at pH 4 exhibited optimal properties: a size of 207.88 nm, a zeta potential of +42.30 mV, and a PDI of 0.62. Biofilms displayed tunable mechanical strength, with a tensile strength of 3.48 MPa using 5% glycerol and 2% chitosan and an elongation at break of 24.99 mm. TGA showed a two-step degradation process (98.19% mass loss). Ag ionization was 62.57 mg/L in the liquid nanocomposite and 184.07 mg/kg in the biofilms. These findings highlight AgChNPs' potential for controlled-release properties and enhanced mechanical performance, supporting sustainable agricultural applications.