Abstract:

Ellagic acid-modified silver nanoparticles （EA-AgNPs） were synthesized through one-pot green synthesis approach by using ellagic acid as both reducing agent and stabilizer. The product of EA-AgNPs was characterized by ultraviolet-visible spectrophotometry, particle-size distribution analysis, zeta potential measurement, transmission electron microscopy （TEM）, X-ray diffraction （XRD）, and Fourier transform infrared spectroscopy （FTIR）. Its antibacterial activity was also investigated. The optimized conditions for preparation of EA-AgNPs were obtained, in which the molar ratio of ellagic acid: silver nitrate was 1∶1, the pH value was 10, and the mixture was heated at 85 ℃ while stirred at stirring speed of 200 r/min for 1 hour. The nanoparticles were spherical, with average particle size of 20-50 nm. The zeta potential was measured as -25 mV. TEM and XRD analyses revealed that the nanoparticles exhibited good dispersity and crystalline structure. The antibacterial tests demonstrated that EA-AgNPs exhibited significant antibacterial activities against Escherichia coli （E. coli） and Staphylococcus aureus （S. aureus）, with minimum inhibitory concentrations （MIC） of 1.56 and 6.25 μg/mL, respectively. Such antibacterial activities were remarkably superior to those of free ellagic acid, showing 40-fold improvement against E. coli and 5-fold improvement against S. aureus. Time-kill curve assays further confirmed its rapid bactericidal efficacy, particularly against E. coli. Cytotoxicity tests showed that EA-AgNPs exhibited low toxicity to mammalian 3T3 cells at effective antibacterial concentrations, indicative of good biocompatibility. In conclusion, EA-AgNPs exhibited notable in vitro antibacterial activity and favorable biocompatibility. This work could provide theoretical support and technical reference for high-value utilization of polyphenols derived from agricultural by-products.

Key words: ellagic acid-modified silver nanoparticle, green synthesis, antibacterial