Biosynthesis, Characterization, and Antibacterial Activity of Silver Nanoparticles Produced from Rice Straw Biomass

Silver nanoparticles (AgNPs) were synthesized from AgNO3 using rice straw biomass as the reducing agent at room temperature via light irradiation. Full wavelength scanning with UV/Vis spectrophotometer was used to study the effect of light intensity, reaction time, and concentrations of rice straw biomass and AgNO3 during AgNPs synthesis. Surface plasmon resonance (SPR) showed that the peak wavelength of synthesized silver nanoparticles arose at 425 nm, the optimal light intensity observed was 60,000 lx, and the optimal reaction time was 140 min. The optimum concentrations of the rice straw biomass and AgNO3 used were 4 mg/mL and 2 mM, respectively. The AgNPs were characterized by X-ray diffraction (XRD) analysis. The zeta potential of AgNPs reached -21.2 mV. In addition, the AgNPs synthesized by rice straw biomass revealed antimicrobial activity against Escherichia coli, Pseudomonas aeruginosa, Bacillus subtilis, and Staphyloccus aureus. The inhibition rate reached about 97.17 ± 2.01% when the concentration of AgNPs solution used was 8 μg/mL. In the detection of antimicrobial effect of AgNPs and antibiotics, the antibacterial activity was found to be superior to that of antibiotics alone.