Green Synthesis of Silver Nanoparticles Using Fructus mori Juice: Characterization and Research of Antioxidant and Antibacterial Properties

Novel antibacterial silver nanomaterials have become promising substitutes for traditional antibiotics, because pathogens do not develop resistance to them. However, it is necessary to produce silver nanoparticles with appropriate size and better performance through a green and simple synthesis process. In the present study, Fructus mori-composite silver nanoparticles (M-AgNPs) were greenly synthesized using medicinal plant mulberry fruits (Fructus mori), with silver nitrate (AgNO3) as a precursor. UV-Vis spectroscopy and X-ray diffraction (XRD) indicated the formation of silver nanoparticles with face centered cubic structure. Fourier transform infrared (FTIR) spectroscopy confirmed the reducing and capping effects of mulberry fruits' active components (polyphenols, flavonoids, etc.) on M-AgNPs. The reaction parameters including temperature, time, pH, and concentration of AgNO3 were gradually optimized. The particle size and morphology of M-AgNPs were measured by dynamic light scattering (DLS) and transmission electron microscopy (TEM) techniques. The minimum particle size of M-AgNPs was about 30 nm, and they were approximately spherical and equably distributed. The excellent stability of M-AgNPs ensured that no agglomeration occurred for up to 60 days. The antioxidant activity of M-AgNPs was evaluated by 1,1-diphenyl-2-trinitrophenylhydrazine (DPPH) assay, and the DPPH radical clearance rate of M-AgNPs was up to about 79%. Greenly synthesized M-AgNPs exhibited better antibacterial activity than chemically synthesized commercial silver nanoparticles (C-AgNPs), due to the active molecules attached to their surfaces. The inhibition zone diameters of M-AgNPs against P.aeruginosa, E.coli and S.aureus were 13.9±0.4、12.2±0.3、12.8±0.7 mm, respectively. Such greenly synthesized AgNPs from medicinal plants have good prospects in the field of biomedicine.