目的 使用穿心莲Andrographis paniculata（AP）绿色合成纳米银（AP@silver nanoparticles，AP@AgNPs），确定最佳合成工艺；研究AP@AgNPs理化性质、抗氧化和抑菌活性及杀菌机制。方法 使用穿心莲提取液在超声加热条件下合成AP@AgNPs，以AP@AgNPs粒径、还原反应效率及多分散性为指标，通过评价生物合成参数确定最佳合成工艺，激光粒度仪、透射电子显微镜（transmission electron microscope，TEM）、X射线晶体衍射（X-ray crystal diffraction，XRD）和傅里叶变换红外光谱（Fourier transform infrared spectroscopy，FT-IR）表征AP@AgNPs粒径、多分散性、表面性质、形貌、晶型和还原机制，计算1,1-二苯基-2-三硝基苯肼（1,1-diphenyl-2-trinitrophenylhydrazine，DPPH）自由基捕获率评价抗氧化能力，测量细菌生长动力学评价抑菌活性，流式细胞术评价AP@AgNPs内吞作用，初步揭示杀菌机制。结果 穿心莲提取液pH 10.0、AgNO₃浓度10.0 mmol/L、50 ℃反应6.0 h可得近球形、分散均匀、表面带负电荷、粒径在30～40 nm、晶型为面心立方、至少2个月内稳定的AP@AgNPs。合成的AP@AgNPs对DPPH自由基具有很强的捕获能力，150.0 μg/mL时捕获率为95.1%；对大肠杆菌Escherichia coli的最小抑菌浓度（minimum inhibitory concentration，MIC）为20.0 μg/mL，而金黄色葡萄球菌Staphylococcus aureus的MIC大于100.0 μg/mL；AP@AgNPs可被2种细菌内吞，其中大肠杆菌可能通过细胞内机制死亡，而金黄色葡萄球菌的细胞膜会被损伤导致细胞内物质流出。结论 使用穿心莲可绿色制备性质稳定、具有抗氧化和选择性抑制大肠杆菌活性的AP@AgNPs，其可被大肠杆菌和金黄色葡萄球菌内吞。

Objective To fabricate silver nanoparticles (AP@AgNPs) by Chuanxinlian (Andrographis paniculata, AP) with optimization of biosynthesis parameters. To character the AP@AgNPs followed by disclosing the antioxidation, antibacterial activity and the mechanism of sterilization. Methods To biosynthesize AP@AgNPs under ultrasound and heating. To confirm optimal biosynthesis parameters by evaluating the influence on reaction efficiency, average size and polydispersity. To characterize AP@AgNPs by laser granularity analyzer, transmission electron microscopy (TEM), X-ray diffraction (XRD) and Fourier transform infrared spectroscopy (FT-IR). To evaluate antioxidation activity by calculating the scavenging rate of DPPH. To evaluate antibacterial activity by mapping the curves of growth kinetics and to disclose the mechanism of sterilization by calculating the mean of side scattering channel (SSC) measured by flow cytometry. Results At pH 10.0 and with 10.0 mmol/L of AgNO₃, the AP@AgNPs could be synthesized by AP at 50 ℃ under ultrasonic, where the AP@AgNPs are spherical shape with average size 30—40 nm and a face-centered cubic structure, and exist in monodispersed form covered by negatively charged complex with long-term stability (2 months). The AP@AgNPs display superior antioxidation activity, where the 1,1-diphenyl-2-trinitrophenylhydrazine (DPPH) scavenging rate is 95.1% after adding 150.0 μg/mL of AP@AgNPs. And AP@AgNPs prefer to inhibit the growth of Escherichia coli rather than Staphylococcus aureus, where the minimum inhibitory concentration (MIC) of E. coli is 20.0 μg/mL but for S. aureus, it is higher than 100.0 μg/mL. The AP@AgNPs reveal significant uptake into both E. coli and S. aureus, and may damage the cell membrane of S. aureus. Conclusion AP could act as a proper substance to fabricate AgNPs with long-term stability and superior antioxidation and antibacterial activity.

R283.6

国家自然科学基金资助项目(82274753);国家自然科学基金资助项目(22103007);陕西省创新能力支撑计划(2023KJXX-063);陕西省重点研发计划(2024SF-YBXM-517);陕西省重点研发计划(2024SF-YBXM-426);陕西中医药大学2023年度科技创新人才体系建设计划(2023-LJRC-03);秦药特色资源研究开发重点实验室开放课题项目(SUCM-QM202207)