State Key Laboratory of Pollution Control and Resource Reuse, School of the Environment, Nanjing University, Nanjing, 210023, Jiangsu Province, China.
Key Laboratory of the Coastal and Wetland Ecosystems of Ministry of Education, College of the Environment and Ecology, Xiamen University, Xiamen, 361102, Fujian Province, China.
Nat Commun. 2021 Feb 5;12(1):812. doi: 10.1038/s41467-021-21080-z.
Carbon dots (CDs) are photoluminescent nanomaterials with wide-ranging applications. Despite their photoactivity, it remains unknown whether CDs degrade under illumination and whether such photodegradation poses any cytotoxic effects. Here, we show laboratory-synthesized CDs irradiated with light degrade into molecules that are toxic to both normal (HEK-293) and cancerous (HeLa and HepG2) human cells. Eight days of irradiation photolyzes 28.6-59.8% of the CDs to <3 kilo Dalton molecules, 1431 of which are detected by high-throughput, non-target high-performance liquid chromatography-quadrupole time-of-flight mass spectrometry. Molecular network and community analysis further reveal 499 cytotoxicity-related molecules, 212 of which contain polyethylene glycol, glucose, or benzene-related structures. Photo-induced production of hydroxyl and alkyl radicals play important roles in CD degradation as affected by temperature, pH, light intensity and wavelength. Commercial CDs show similar photodegraded products and cytotoxicity profiles, demonstrating that photodegradation-induced cytotoxicity is likely common to CDs regardless of their chemical composition. Our results highlight the importance of light in cytocompatibility studies of CDs.
碳点（CDs）是一类具有广泛应用前景的发 光纳米材料。尽管它们具有光活性，但目前仍不清楚 CDs 是否会在光照下降解，以及这种光降解是否会产生细胞毒性作用。在这里，我们展示了实验室合成的 CDs 在光照下会降解成对正常（HEK-293）和癌细胞（HeLa 和 HepG2）都有毒性的分子。8 天的辐照可将 28.6-59.8%的 CDs 光解为 <3 千道尔顿的分子，其中 1431 种分子通过高通量、非靶向高效液相色谱-四极杆飞行时间质谱进行了检测。分子网络和群落分析进一步揭示了 499 种与细胞毒性相关的分子，其中 212 种含有聚乙二醇、葡萄糖或苯相关结构。羟基和烷基自由基的光诱导产生在 CD 降解中起着重要作用，其受温度、pH 值、光强和波长的影响。商业 CDs 表现出相似的光降解产物和细胞毒性特征，这表明光降解诱导的细胞毒性可能是 CDs 的普遍现象，而与它们的化学成分无关。我们的研究结果强调了光在 CDs 细胞相容性研究中的重要性。
