Nie Xiaolin, Jiang Chenyu, Wu Shuanglin, Chen Wangbingfei, Lv Pengfei, Wang Qingqing, Liu Jingyan, Narh Christopher, Cao Xiuming, Ghiladi Reza A, Wei Qufu
Key Laboratory of Eco-Textiles, Ministry of Education, Jiangnan University, Wuxi 214122, China.
Department of Chemistry, North Carolina State University, Raleigh, NC 27695, USA.
J Photochem Photobiol B. 2020 Mar 23;206:111864. doi: 10.1016/j.jphotobiol.2020.111864.
Carbon nanomaterials have increasingly gained the attention of the nano-, photo- and biomedical communities owing to their unique photophysical properties. Here, we facilely synthesized carbon quantum dots (CQDs) in a one-pot solvothermal reaction, and demonstrated their utility as photosensitizers for in vitro antibacterial photodynamic inactivation (aPDI). The bottom-up synthesis employed inexpensive and sustainable starting materials (citric acid), used ethanol as an environmentally-friendly solvent, was relatively energy efficient, produced minimal waste, and purification was accomplished simply by filtration. The CQDs were characterized by both physical (TEM, X-ray diffraction) and spectroscopic (UV-visible, fluorescence, and ATR-FTIR) methods, which together confirmed their nanoscale dimensions and photophysical properties. aPDI studies demonstrated detection limit inactivation (99.9999 + %) of Gram-negative Escherichia coli 8099 and Gram-positive Staphylococcus aureus ATCC-6538 upon visible light illumination (λ ≥ 420 nm, 65 ± 5 mW/cm; 60 min). Post-illumination SEM images of the bacteria incubated with the CQDs showed perforated and fragmented cell membranes consistent with damage from reactive oxygen species (ROS), and mechanistic studies revealed that the bacteria were inactivated by singlet oxygen, with no discernable roles for other ROS (e.g., superoxide or hydroxyl radicals). These findings demonstrated that CQDs can be facilely prepared, operate via a Type II mechanism, and are effective photosensitizers for in vitro aPDI.
碳纳米材料因其独特的光物理性质，越来越受到纳米、光学和生物医学领域的关注。在此，我们通过一锅溶剂热反应简便地合成了碳量子点（CQDs），并证明了它们作为体外抗菌光动力灭活（aPDI）光敏剂的效用。这种自下而上的合成方法使用了廉价且可持续的起始原料（柠檬酸），以乙醇作为环境友好型溶剂，相对节能，产生的废物极少，并且仅通过过滤即可完成纯化。通过物理方法（透射电子显微镜、X射线衍射）和光谱方法（紫外可见光谱、荧光光谱和衰减全反射傅里叶变换红外光谱）对CQDs进行了表征，这些方法共同证实了其纳米级尺寸和光物理性质。aPDI研究表明，在可见光照射下（λ≥420 nm，65±5 mW/cm²；60分钟），革兰氏阴性大肠杆菌8099和革兰氏阳性金黄色葡萄球菌ATCC - 6538的检测限失活率（99.9999 + %）。用CQDs孵育后的细菌光照后扫描电子显微镜图像显示细胞膜穿孔和破碎，这与活性氧（ROS）造成的损伤一致，机理研究表明细菌是被单线态氧灭活的，其他ROS（如超氧阴离子或羟基自由基）没有明显作用。这些发现表明，CQDs可以简便地制备，通过II型机制发挥作用，并且是体外aPDI的有效光敏剂。
