Abstract:[Objective] The aim of this study is to investigate the structural characteristics, antibacterial activity, and antioxidant capacity of silver nanoparticles (AgNPs) prepared from Phyllanthus emblica extract. [Method] AgNPs were prepared with Phyllanthus emblica extract as a reducing agent. The structure of the AgNPs was characterized by X-ray diffraction (XRD), scanning electron microscopy (SEM), photon correlation spectroscopy (PCS), and transmission electron microscopy (TEM). Furthermore, the inhibitory effects of AgNPs at different mass concentrations on Escherichia coli ATCC25922, Staphylococcus aureus ATCC25933, and Pseudomonas aeruginosa PAO1 were assessed, with the minimum inhibitory concentrations (MIC) being determined. In addition, the superoxide anion and ABTS+ free radical scavenging abilities and the reducing capacity of AgNPs were determined. [Result] The AgNPs prepared with Phyllanthus emblica extract presented a face-centered cubic structure with a particle size range from 10 to 30 nm and good dispersion. Their antibacterial properties gradually increased with the rising mass concentration of AgNPs. AgNPs had strong, moderate, and weak inhibitory effects on Escherichia coli ATCC25922, Pseudomonas aeruginosa PAO1, and Staphylococcus aureus ATCC25933, with the MICs of 0.031, 0.063, and 0.125 mg/mL, respectively. AgNPs at high mass concentrations exhibited strong antioxidant properties. At 1.000 to 2.000 mg/mL, AgNPs showed high superoxide anion and ABTS+ free radical scavenging abilities but weak reducing capacity. [Conclusion] The AgNPs prepared by the green method from Pseudomonas emblica extract has good dispersion, strong antibacterial activity, and strong antioxidant capacity. The results provide scientific guidance for the research and development of AgNPs as a preservative and offer a reference for their future application in food preservation.
