制备具有抗氧化及免疫调节功能的氮掺杂碳量子点（NCQDs），通过构建坐骨神经损伤模型，评估其对周围神经损伤修复的影响，并探讨其相关机制。

（1）体外实验：使用二烯丙基二甲基氯化铵、无水柠檬酸合成NCQDs，将NCQDs设置0、10、20、30 μg/mL 4个浓度组，分别为CON组、NCQDs-10组、NCQDs-20组及NCQDs-30组。取小鼠单核巨噬细胞白血病细胞系（RAW 264.7）按实验设计接种于培养板，待细胞贴壁并确认细胞状态良好后，加入相应浓度的NCQDs，分别继续培养1、4 d后检测细胞毒性，培养24 h后检测抗氧化性能。取5只C57幼鼠的背根神经节（DRG）神经元，采用DAPI/NF-200免疫荧光染色观察NCQDs对神经元生长的影响。用NCQDs分别处理DRG神经元12、24 h，验证其对神经元的细胞毒性和免疫调节性能。（2）体内实验：取6周龄C57小鼠构建坐骨神经损伤模型，采用随机数字表法分为对照组和NCQDs组，分别在神经损伤侧局部注射生理盐水与NCQDs。7 d后通过神经染色、脊髓病理切片等实验观察神经修复情况，28 d后通过神经电生理、足迹实验分析及腓肠肌切片染色进一步评估坐骨神经及建模侧肌肉的运动功能恢复情况，通过血清学指标及脏器HE染色评估NCQDs的体内安全性能。

（1）体外实验：NCQDs具有良好的生物相容性，可大幅降低RAW264.7细胞活性，降低ROS表达水平，且30 d内ROS清除率稳定。Zeta电位检测显示，NCQDs的Zeta电位为+6.98 mV。ELISA检测显示，与CON组相比，NCQDs-10组、NCQDs-20组、NCQDs-30组的肿瘤坏死因子-α、白细胞介素（IL）-6、IL-8及IL-1β的表达水平均降低，差异有统计学意义（P<0.05）。（2）体内实验：与对照组相比，NCQDs组阳性神经元数目显著增多，损伤部位再生轴突数目增加、距离延长，动作电位潜伏期显著缩短，传导速度加快，差异均有统计学意义（P<0.05）；行为学分析显示足迹面积、接触密度及足底压力显著改善，腓肠肌平均肌纤维直径显著增加，差异均有统计学意义（P<0.05）。2组小鼠的血液学、血清生化指标及心、肝、脾、肺、肾等主要脏器组织学检查均未见明显异常。

NCQDs具有良好的体内体外安全性，可通过抗炎、抗氧化作用显著促进坐骨神经损伤的修复。

To develop nitrogen-doped carbon quantum dots (NCQDs) with antioxidant and immunomodulatory functions and evaluate their effects on peripheral nerve injury repair using a sciatic nerve injury model.

(1) In vitro experiment: NCQDs were synthesized using diallyldimethylammonium chloride and anhydrous citric acid. NCQDs were set to 4 concentration groups of 0, 10, 20, and 30 μg/mL, named CON group, NCQDs-10 group, NCQDs-20 group, and NCQDs-30 group. Mouse monocyte macrophage leukemia cell line (RAW 264.7) was inoculated into a culture plate according to the experimental design. After the cells adhered to the wall and the cell status was confirmed to be good, corresponding concentrations of NCQDs were added and cultured for 1 and 4 d, respectively, to detect cytotoxicity. After 24 h of culture, the antioxidant performance was detected. Five dorsal root ganglia (DRG) neurons from C57 mice were taken, and DAPI/NF-200 immunofluorescence staining was used to observe the effect of NCQDs on neuronal growth. NCQDs were used to treat DRG neurons for 12 and 24 h to verify their cytotoxicity and immunomodulatory properties on neurons. (2) In vivo experiment: A sciatic nerve injury model was established in 6-week-old C57 mice, which were randomly divided into a control group and a NCQDs group. Normal saline and NCQDs were locally injected into the injury site, respectively. At 7 d post-injury, nerve regeneration was assessed via nerve histology and spinal cord pathological sections. At 28 d post-injury, functional recovery of the sciatic nerve and ipsilateral hindlimb muscles were further evaluated using electrophysiology, footprint analysis, and gastrocnemius muscle histological staining. Serum biochemical parameters and H&E staining of major organs were performed to assess the in vivo biosafety of NCQDs.

(1) In vitro experiment: NCQDs exhibited excellent biocompatibility and can significantly reduce RAW264.7 cell activity, decrease ROS expression levels, and maintain a stable ROS clearance rate within 30 d. Zeta potential detection showed that the Zeta potential of NCQDs was +6.98 mV. Enzyme-linked immunosorbent assay detection showed that compared with the CON group, the expression levels of tumor necrosis factor-α, interleukin (IL)-6, IL-8, and IL-1β in the NCQDs-10 group, NCQDs-20 group, and NCQDs-30 group were all reduced, and the differences were statistically significant (P<0.05). (2) In vivo experiment: Compared with the control group, the NCQDs group showed a significant increase in the number of positive neurons, an increase in the number and distance of regenerated axons at the injury site, a significant reduction in action potential latency, and an increase in conduction velocity, with statistically significant differences (P<0.05); Behavioral analysis showed significant improvements in footprint area, contact density, and plantar pressure, while the average diameter of gastrocnemius muscle fibers increased significantly, with statistically significant differences (P<0.05). Hematological and serum biochemical indicators, as well as histological examinations of major organs such as heart, liver, spleen, lungs, and kidneys in two groups of mice, showed no significant abnormalities.

NCQDs possess favorable biosafety both in vitro and in vivo, they significantly enhance sciatic nerve repair through combined anti-inflammatory and antioxidant mechanisms.