Eco-Friendly Green Synthesis of Rubropunctatin Functionalized Silver Nanoparticles and Evaluation of Antibacterial Activity

In order to solve the problems of rubropunctatin insoluble in water and its low bioavailability, and explore the synthesis method of green silver nanoparticles, rubropunctatin was used as reducing agent and blocking agent, rubropunctatin-functionalized silver nanoparticles (R-AgNPs) were successfully synthesized. The distinctive absorption peak at 410 nm confirmed the formation of R-AgNPs. Zeta potential measurement showed excellent stability of R-AgNPs with negative values of −29.81 ± 0.37 mV. The results of TEM and XRD showed that the prepared R-AgNPs were round, well dispersed and crystallized with average particle size of 13.54 ± 0.42 nm. FT-IR and XPS studies show that functional groups are involved in R-AgNPs synthesis. The antibacterial activity of R-AgNPs was compared with commercial silver nanoparticles (AgNPs) by microdilution method. The results showed that R-AgNPs (MIC 7.81 μg/mL) has stronger antibacterial activity than commercial AgNPs. The bacteria morphology was observed by the live and dead (SYTO 9/PI) staining assay and SEM showed that the antibacterial effect of R-AgNPs was caused by the destruction of the bacterial cell membrane. Cytotoxicity of rubropunctatin-functionalized silver nanoparticles and commercial silver nanoparticles on mouse fibroblast 3T3 cells was assessed by CCK-8 assay. The results showed that the toxicity of rubropunctatin-functionalized silver nanoparticles to 3T3 cells was lower than that of commercial silver nanoparticles. In summary, synthesis of silver nanoparticles using rubropunctatin is a green synthesis method, and R-AgNPs is a potential antibacterial agent.