Abstract: Objective　To study the sterilization effect and the cytotoxic effect of photodynamic therapy（PDT）mediated by the novel composite photosensitizer（toluidine blue-carboxmethyl chitosan-carbon nanotubes），so as to provide a theoretical basis for its further application in clinical practice. Methods    （1）The experimental groups included photosensitizer groups（1.0，1.5，2.0，2.5 g/L，A1 to A4），light intensity groups （53，106，159，212 mW/cm2，B1 to B4）and light dose groups（12，24，36，48 J/cm2，C1 to C4），which were given PDT treatment，while the control groups （A5,B5,C5） were not given photosensitizer or light. Analyze and compare the sterilization effect of each group.（2）The experiment was divided into PDT group and the non-irradation group. The experimental group set the mass concentration of photosensitizer was 1.5，2.0，2.5 g/L，PDT was carried out under the light intensity of 212 mw/cm2 and the light dose of 60 J/cm2，each experimental group was set the control group for the mass concentration of photosensitizer was 0 g/L. The relative growth rate（RGR）of cells was measured by the MTT assay to evaluate the cytotoxicity. Results    （1）There were statistically significant differences among the subgroups of photosensitizer group，light intensity group and light dose group（F = 23.29，28.15，25.36，P < 0.05）. The highest sterilization rate was obtained in A2，B4 and C3 subgroups，and C3 was higher than A2 and B4 （P < 0.05）. （2）The RGR of PDT group and non-irradiation group showed a decreasing trend with the increase of the mass concentration of composite photosensitizer，and the differences were statistically significant（F = 23.06，24.15，P < 0.05）.When the mass concentration of photosensitizer was 2.5 g/L，the RGR of PDT group and non-irradiation group was significantly lower than that of control group，and there was statistical difference（P < 0.05）. The cytotoxicity of each group treated with different mass concentration of composite photosensitizer PDT was grade 0 and grade 1，which was qualified. Conclusion    PDT mediated by the novel composite photosensitizer has a good sterilization effect on the supragingival bacteria. When applied locally at effective sterilization concentration in PDT，the novel composite photosensitizer has a low level of cytotoxicity and good safety. 

Key words: composite photosensitizer；photodynamic therapy, PDT；supragingival plaque；sterilization rate；cytotoxicity

摘要： 目的    研究新型复合光敏剂（甲苯胺蓝-羧甲基壳聚糖-碳纳米管复合光敏剂）介导的光动力疗法（photodynamic therapy，PDT）的灭菌效果及细胞毒性，为其应用于临床提供理论基础。方法    （1）根据不同的复合光敏剂质量浓度（1.0、1.5、2.0、2.5 g/L）、光强度（53、106、159、212 mW/cm2）和光剂量（12、24、36、48 J/cm2）依次分为光敏剂组（A1 ~ A4亚组）、光强度组（B1 ~ B4亚组）、光剂量组（C1 ~ C4亚组），进行PDT处理；对照组（A5、B5、C5亚组）为不加复合光敏剂且不用激光照射。分析比较各组的灭菌效果。（2）在人牙周膜细胞的培养基中分别设置复合光敏剂质量浓度为1.5、2.0、2.5 g/L，在光强度212 mW/cm2、光剂量60 J/cm2下进行PDT处理的记为PDT组，不进行光照的记为避光组；以不加入复合光敏剂（0 g/L）进行PDT或避光处理的为各自的对照组。采用MTT法检测细胞相对增殖率（relative growth rat，RGR），并评价细胞毒性。结果    （1）光敏剂组、光强度组、光剂量组的组内各亚组间总的比较，差异均有统计学意义（F值分别为23.29、28.15、25.36，均P < 0.05）。各组中灭菌率最高的分别为A2、B4、C3亚组，其中C3亚组的灭菌率高于A2、B4亚组，差异有统计学意义（P < 0.05）。（2）随复合光敏剂质量浓度的增加，PDT组和避光组的RGR均呈降低趋势，差异均有统计学意义（F值分别为23.06和24.15，均P < 0.05）。当光敏剂质量浓度为2.5 g/L时，PDT组和避光组较对照组RGR明显降低，差异均有统计学意义（均P < 0.05）。各组应用不同质量浓度复合光敏剂PDT处理后的细胞毒性均为0和1级，属于合格。结论    新型复合光敏剂介导的PDT对龈上菌斑中的细菌具有较好的灭活作用，局部应用有效灭菌浓度的复合光敏剂介导PDT的细胞毒性级别低，具有很好的安全性。

关键词: 复合光敏剂, 光动力疗法, 龈上菌斑, 灭菌率, 细胞毒性