College of Pharmacy, Guangxi University of Chinese Medicine, Nanning, China.
College of Pharmacy, Guangxi University of Chinese Medicine, Nanning, China.
Photodiagnosis Photodyn Ther. 2021 Sep;35:102417. doi: 10.1016/j.pdpdt.2021.102417. Epub 2021 Jun 26.
Background and objective Photodynamic therapy (PDT) and photothermal therapy (PTT) have gradually become options for select anti-tumor and antibacterial treatment . The combination of PDT and PTT show great research value, which may greatly improve the curative effect. The aim of the present study was to prepare a compound system of polydopamine and curcumin (PDA-Cur nanocomposites) with excellent antibacterial effect towards Gram-positive and Gram-negative bacteria. Methods Dopamine hydrochloride was oxidized and self polymerized in alkaline condition to form PDA-Cur nanocomposites. The structure and morphology of PDA-Cur were characterized by transmission electron microscopy (TEM), scanning electron microscopy (SEM), laser scattering microscopy (LSM), ultraviolet spectrophotometer (UV-vis), infrared spectroscopy (IR) and fluorescence emission spectrometer. Using 1,1-diphenyl-2-picrylhydrazyl radical (DPPH), 1,3-diphenylbenzofuran (DPBF) and 2',7'-Dichlorodihydrofluorescein diacetate (DCFH-DA) were used to detect the production of reactive oxygen species (ROS). The thermal stability of PDA-Cur nanocomposites was investigated by temperature rising test. The antibacterial effect of PDA-Cur was determined by plate counting technique using Staphylococcus aureus (S. aureus) and Escherichia coli (E. coli) as models. In addition, the stability and antibacterial mechanism of PDA-Cur were investigated. Finally, the biocompatibility was evaluated by cytotoxicity and hemolysis tests. Results The compound system of polydopamine and curcumin was successfully prepared, which showed improved stability compared with Cur. The consumption of DPBF by the singlet oxygen produced by PDA-Cur was as high as 80%. In the heating test, the highest temperature increased to 59 °C, which contributed to the photodynamic and photothermal inactivation of bacteria. PDA-Cur nanocomposites showed good antibacterial activity against S. aureus and E. coli. Under 405 nm light, the bactericidal rate of PDA-Cur against S. aureus can reach 100% at a low concentration of 10 nM, and that against E. coli was 100% at 1 nM. Under 405 + 808 nm light, the bactericidal rate of PDA-Cur against E. coli enhanced to 100% at 0.1 nM. In addition, PDA-Cur had low cytotoxicity and negligible hemolytic activity, showing good biocompatibility. Conclusion PDA-Cur nanocomposites had good photodynamic effect, photo thermal conversion ability and biocompatibility. Compared with free Cur, the antibacterial activity of PDA-Cur was significantly improved, and the antibacterial effect with combined light was stronger than that of free Cur. Therefore, the construction of PDA-Cur nanocomposites have confirmed that the combination of PDT and PTT can greatly improve the antibacterial effect and reach bactericidal effect at low concentration, which provides a strategy for the design of next generation antimicrobial agents.
背景与目的 光动力疗法（PDT）和光热疗法（PTT）已逐渐成为选择抗肿瘤和抗菌治疗的方法。PDT 和 PTT 的联合具有很大的研究价值，可能极大地提高疗效。本研究旨在制备一种具有优异的抗革兰氏阳性菌和革兰氏阴性菌的抗菌作用的聚多巴胺和姜黄素（PDA-Cur 纳米复合材料）的复合体系。
方法 盐酸多巴胺在碱性条件下氧化自聚合形成 PDA-Cur 纳米复合材料。通过透射电子显微镜（TEM）、扫描电子显微镜（SEM）、激光散射显微镜（LSM）、紫外分光光度计（UV-vis）、红外光谱（IR）和荧光发射光谱对 PDA-Cur 的结构和形态进行了表征。使用 1,1-二苯基-2-苦基肼基（DPPH）、1,3-二苯基苯并呋喃（DPBF）和 2',7'-二氯二氢荧光素二乙酸酯（DCFH-DA）检测活性氧（ROS）的产生。通过升温试验研究了 PDA-Cur 纳米复合材料的热稳定性。采用平板计数法，以金黄色葡萄球菌（S. aureus）和大肠杆菌（E. coli）为模型，测定 PDA-Cur 的抗菌效果。此外，还研究了 PDA-Cur 的稳定性和抗菌机制。最后，通过细胞毒性和溶血试验评估了 PDA-Cur 的生物相容性。
结果 成功制备了聚多巴胺和姜黄素的复合体系，与姜黄素相比，其稳定性得到了提高。PDA-Cur 产生的单线态氧对 DPBF 的消耗高达 80%。在加热试验中，最高温度升高到 59°C，有助于光动力和光热杀菌。PDA-Cur 纳米复合材料对金黄色葡萄球菌和大肠杆菌表现出良好的抗菌活性。在 405nm 光下，浓度低至 10 nM 时，PDA-Cur 对金黄色葡萄球菌的杀菌率可达 100%，对大肠杆菌的杀菌率可达 100%，浓度为 1 nM。在 405+808nm 光下，PDA-Cur 对大肠杆菌的杀菌率增强至 0.1 nM 时达到 100%。此外，PDA-Cur 的细胞毒性低，溶血活性可忽略不计，具有良好的生物相容性。
结论 PDA-Cur 纳米复合材料具有良好的光动力效应、光热转换能力和生物相容性。与游离姜黄素相比，PDA-Cur 的抗菌活性明显提高，联合光的抗菌效果强于游离姜黄素。因此，PDA-Cur 纳米复合材料的构建证实，PDT 和 PTT 的联合可以极大地提高抗菌效果，并达到低浓度杀菌效果，为下一代抗菌剂的设计提供了一种策略。
