目的 使用山茱萸水提液在温和条件下制备银纳米颗粒（AgNPs）、探究还原反应机制并研究其抑菌活性。方法 采用紫外-可见光谱监测AgNPs的生成，红外光谱研究还原机制，激光粒度仪和透射电镜表征粒径，表面性质和形貌，2倍稀释法研究AgNPs的抑菌活性。结果 山茱萸水提液在pH 9.0时超声反应4 h是还原制备AgNPs的最佳条件，得近球形AgNPs，平均粒径58.73 nm，均匀稳定、分散性好。黄酮类化合物可能起还原作用，同时水提液中活性成分在AgNPs表面形成保护层，防止团聚，增加了AgNPs的稳定性，制得的AgNPs对大肠杆菌和金黄色葡萄球菌的抑制率比化学法制备的AgNPs分别增加20、40倍。结论 山茱萸水提液可在温和条件下制备AgNPs，该AgNPs与化学制备法相比有更强的抗菌性能。结果表明该方法合成出的AgNPs性能稳定，可以作为新型抗菌剂。

Objective To develope a novel method to generate silver nanoparticles (AgNPs) in a mild condition by using the Cornus officinalis aqueous extract, study their antibacterial activity, and explore the mechanism of reduction reaction.Methods The formation of AgNPs was confirmed by UV-visible spectroscopy; The particle size, surface properties, and morphology features of AgNPs were characterized by laser particle analyzer as well as transmission electron microscopy; The mechanism of reduction reaction was studied by IR. The antibacterial activity of AgNPs was investigated by disk agar diffusion method.Results The AgNPs were prepared under mild reaction conditions by C. officinalis aqueous extract, the optimum condition is ultrasonic reaction for 4 h (pH 9.0). Quasi-spherical shaped AgNPs were synthesized with average particle size of 58.73 nm, which was uniform, stable, and well dispersed. The presence of flavonoids in C. officinalis aqueous extract may be the reductant to produce the AgNPs. In the meantime, the active components in the aqueous extract form a protective layer on the surface of AgNPs to prevent aggregation and increase the stability of AgNPs. Compared with the chemically synthesized AgNPs, the antibacterial activity of AgNPs generated by C. officinalis aqueous extract increased 20-fold and 40-fold for Escherichia coli and Staphylococcus aureus, respectively.Conclusion C. officinalis aqueous extract can prepare AgNPs under mild conditions, the flavonoids in the extract may be the reductive reagent and can stabilize AgNPs. The AgNPs prepared by this method have stronger antibacterial properties than those prepared by chemical method. The AgNPs synthesized by this method are stable and can be used as a new antimicrobial agent.

国家自然科学基金资助项目（21705029）；陕西中医药大学校级基金资助项目（2017QN22）；陕西中医药大学博士科研启动金（10408001）