目的 从白及Bletilla striata、刺梨Rosa roxburghii、灵芝Ganoderma lucidum和天麻Gastrodia elata中筛选出抑菌效果最佳的中药碳点，系统探究锰离子掺杂灵芝碳点（manganese-dopedGanoderma lucidum carbon nanodots，Mn-GLCDs）的理化性质、光热性能、抗菌活性与机制。方法 采用水热法制备白及、刺梨、灵芝和天麻4种中药碳点，通过抑菌活性筛选出性能最优的中药碳点，并对其锰掺杂化中药碳点的形貌、结构、体外光热性能进行表征。通过抑菌圈、细菌共培养以及生物膜抑制和破坏实验，评价其在近红外（near infrared，NIR）光照射下对金黄色葡萄球菌Staphylococcus aureus和大肠杆菌Escherichia coli的抑菌性能。通过细菌内活性氧荧光检测［2′,7′-二氯二氢荧光素二乙酸酯探针（2′,7′-dichlorodihydrofluorescein diacetate，DCFH-DA）］初步探究其抗菌机制。以溶血实验及细胞毒性试验评估其生物安全性。结果GLCDs的抑菌作用显著优于白及、刺梨和天麻碳点。Mn-GLCDs粒径约为5 nm，表面富含-OH、-NH₂、C＝O、C-N-C及C-O-C等亲水官能团。X射线光电子能谱（X-ray photoelectron spectroscopy，XPS）、电感耦合等离子体质谱（inductively coupled plasma mass spectrometry，ICP-MS）证实Mn²⁺质量分数为0.83%，以配位形式稳定存在于碳点骨架中。UV-Vis吸收峰红移及拉曼光谱D峰与G峰强度比（intensity ratio of D-band to G-band，I_D/I_G）＞1表明，Mn²⁺的掺杂缩小了能带隙并增加了结构缺陷密度。光热性能评价结果显示，Mn-GLCDs在808 nm激光（1.5 W/cm²）照射下能迅速升温，光热转换效率为35.03%；6次循环升温稳定性测试中最高温度波动小于6%，表明其具有良好的光热稳定性。荧光性能测试结果表明，荧光量子产率为20.51%，具有激发波长依赖性。体外抑菌实验结果表明，与GLCDs相比，Mn-GLCDs在NIR光照射下，对金黄色葡萄球菌和大肠杆菌2种细菌的抑菌作用最佳，能显著抑制、破坏细菌生物膜。细菌内活性氧检测结果显示，Mn-GLCDs在NIR光照射下，可使金黄色葡萄球菌和大肠杆菌内活性氧水平分别升高至阴性对照组的6.75倍和5.44倍。安全性评价显示，Mn-GLCDs在抑菌浓度范围内溶血率低于5%，对小鼠成纤维细胞（L929，NCTC clone 929）、小鼠单核巨噬细胞白血病细胞（RAW 264.7）细胞均无明显毒性。结论 首次构建了Mn-GLCDs，显著提升其光热转换能力与抑菌活性，其机制与其诱导细菌内活性氧相关，为新型中药纳米抗菌剂开发提供了实验依据。

Objective To screen for the most effective antimicrobial carbon dots from the traditional Chinese medicines Baiji (Bletilla striata), Cili (Rosa roxburghii), Lingzhi (Ganoderma lucidum) and Tianma (Gastrodia elata), and to systematically investigate the physicochemical properties, photothermal performance, antibacterial activity and mechanism of manganese-doped G. lucidum carbon dots (Mn-GLCDs). Methods Four kinds of herbal carbon dots derived from B. striata, R. roxburghii, G. lucidum and G. elata were prepared by a conventional hydrothermal method. The carbon dots with optimal antibacterial activity were screened out, and the morphology, structure and in vitro photothermal performance of the manganese-doped carbon dots were characterized. The antibacterial performance against Staphylococcus aureus and Escherichia coli under near-infrared (NIR) irradiation was evaluated through zone of inhibition assays, bacterial co-culture experiments, and biofilm inhibition and disruption tests. The antibacterial mechanism was preliminarily investigated by intracellular active oxygen fluorescence detection using a DCFH-DA probe. Biosafety was assessed by hemolysis assay and cytotoxicity test. Intracellular reactive oxygen species (ROS) fluorescence measurement using the 2′,7′-dichlorodihydrofluorescein diacetate (DCFH-DA) probe was adopted to preliminarily elucidate its antibacterial mechanism. Hemolysis assays and cytotoxicity evaluations were conducted to verify their biological safety. Results GLCDs possessed remarkably stronger antibacterial activity than carbon dots prepared from B. striata, R. roxburghii and G. elata carbon dots. Mn-GLCDs had a particle size of approximately 5 nm, and their surfaces were rich in hydrophilic functional groups including -OH, -NH₂, C=O, C-N-C and C-O-C. X-ray photoelectron spectroscopy (XPS) and inductively coupled plasma mass spectrometry (ICP-MS) confirmed that the mass fraction of Mn²⁺ reached 0.83%, and Mn²⁺ was stably present in the carbon dot framework in a coordinated form. The red shift of the UV-Vis absorption peak and the Raman I_D/I_G > 1 indicated that Mn²⁺ doping narrowed the bandgap and increased the density of structural defects. Photothermal performance evaluation showed that Mn-GLCDs could rapidly heat up under 808 nm laser irradiation (1.5 W/cm²), with a photothermal conversion efficiency of 35.03%. The maximum temperature fluctuation in six cycles of heating-cooling stability test was less than 6%, indicating good photothermal stability. Fluorescence performance test showed a fluorescence quantum yield of 20.51% and excitation-dependent fluorescence emission. In vitro antibacterial experiments demonstrated that, compared with undoped G. lucidum carbon dots, Mn-GLCDs exhibited the strongest antibacterial effect against S. aureus and E. coli under near-infrared irradiation, and could significantly inhibit and disrupt bacterial biofilms. Intracellular active oxygen detection showed that upon near-infrared irradiation, Mn-GLCDs elevated the active oxygen levels in S. aureus and E. coli to 6.75-fold and 5.44-fold of the negative control group, respectively. Biosafety evaluation showed that the hemolysis rate of Mn-GLCDs was below 5% within the antibacterial concentration range, and Mn-GLCDs exhibited no obvious toxicity to L929 and RAW264.7 cells. Conclusion This study constructs for the first time Mn-GLCDs, which significantly enhance the photothermal conversion capability and antibacterial activity. The mechanism is related to the induction of intracellular active oxygen. This work provides an experimental basis for the development of novel traditional Chinese medicine-based nanoscale antibacterial agents.

R283.6

中药制剂与大健康产品开发贵州省科技创新领军人才工作站（黔科合平台KXJZ[2025]042）；贵州省现代中药创制全省重点实验室（黔科合平台[2025]019）；贵州中医药大学纳米药物技术研究中心（贵中医ZX合字[2024]070）