A fast green synthesis of Ag nanoparticles in carboxymethyl cellulose (CMC) through UV irradiation technique for antibacterial applications

Silver nanoparticles embedded in a carboxymethyl cellulose matrix (AgNPs/CMC) were synthesized by a UV irradiation technique. The successful formation of AgNPs/CMC was examined using UV–Vis spectroscopy, XPS, XRD, TEM, and FTIR. The factors in the preparation process that affected the final products were extensively studied. Thus, 5.0 mM AgNO₃, 0.5 g l⁻¹ CMC, and exposure to UV light for 2.5 min provide excellent combinations to accomplish the AgNPs/CMC formation. Measurements of optical spectra showed that the surface plasmon resonance was localized around 426 nm when the reaction mixture exposed to UV light for 0.5 min; that is monotonically blue shifted to 403 nm up to 2.5 min exposure time. This is manifested in a quick reduction of Ag⁺ into smaller Ag nanoparticles. The IR analysis indicated that hydroxyl and carboxylate groups in CMC were included in coordination with the Ag⁺ ions through displacement of one proton. Upon absorbing UV light, the cellulose hydroxyl and carboxymethylic groups get excited, which reduce Ag⁺ ions to Ag nanoparticles. The TEM image for the optimal designed AgNPs/CMC sample confirmed that AgNPs are formed with many individual spherical shapes and an average diameter of 15.5 nm. This AgNPs/CMC sample showed promising antibacterial properties toward E. coli.