BioNanotechnology and Microbiology Laboratory, Center of Bioinformatics and Integrative Biology (CBIB), Biological Sciences Faculty, Universidad Andres Bello, Santiago, Chile.
Molecular Microbiology Laboratory, Chemistry and Biology Faculty, Universidad de Santiago de Chile, Santiago, Chile.
J Appl Microbiol. 2021 Jul;131(1):155-168. doi: 10.1111/jam.14957. Epub 2020 Dec 18.
Fluorescent semiconductor nanoparticles or quantum dots (QDs) have excellent properties as photosensitizers in photodynamic therapy. This is mainly a consequence of their nanometric size and the generation of light-activated redox species. In previous works, we have reported the low-cost biomimetic synthesis of glutathione (GSH) capped QDs (CdTe-GSH QDs) with high biocompatibility. However, no studies have been performed to determine their phototoxic effect. The aim of this work was to characterize the light-induced toxicity of green (QDs ) and red (QDs ) QDs in Escherichia coli, and to study the molecular mechanism involved.
Photodegradation and reduction power of biomimetic QDs was determined to analyse their potential for radical generation. Escherichia coli cells were exposed to photoactivated QDs and viability was evaluated at different times. High toxicity was determined in E. coli cells exposed to photoactivated QDs, particularly QDs . The molecular mechanism involved in QDs phototoxicity was studied by determining Cd -release and intracellular reactive oxygen species (ROS). Cells exposed to photoactivated QDs presented high levels of ROS. Cells exposed to photoactivated QDs presented high levels of ROS. Finally, to understand this phenomenon and the importance of oxidative and cadmium-stress in QDs-mediated phototoxicity, experiments were performed in E. coli mutants in ROS and Cd response genes. As expected, E. coli mutants in ROS response genes were more sensitive than the wt strain to photoactivated QDs, with a higher effect in green-QDs . No increase in phototoxicity was observed in cadmium-related mutants.
Obtained results indicate that light exposure increases the toxicity of biomimetic QDs on E. coli cells. The mechanism of bacterial phototoxicity of biomimetic CdTe-GSH QDs is mostly associated with ROS generation.
The results presented establish biomimetic CdTe-GSH QDs as a promising cost-effective alternative against microbial infections, particularly QDs .
荧光半导体纳米粒子或量子点（QDs）作为光动力疗法中的光敏剂具有优异的性能。这主要是由于它们的纳米尺寸和产生的光激活氧化还原物种。在以前的工作中，我们已经报道了具有高生物相容性的谷胱甘肽（GSH）封端量子点（CdTe-GSH QDs）的低成本仿生合成。然而，尚未进行研究以确定它们的光毒性。本工作的目的是表征绿色（QDs ）和红色（QDs ）QDs 在大肠杆菌中的光诱导毒性，并研究涉及的分子机制。
为了分析其产生自由基的潜力，测定了仿生 QDs 的光降解和还原能力。将大肠杆菌细胞暴露于光激活的 QDs 中，并在不同时间评估其活力。在暴露于光激活的 QDs 的大肠杆菌细胞中确定了高毒性，尤其是 QDs 。通过测定 Cd 释放和细胞内活性氧（ROS）来研究 QDs 光毒性的分子机制。暴露于光激活的 QDs 的细胞表现出高水平的 ROS。最后，为了理解这种现象以及氧化应激和镉应激在 QDs 介导的光毒性中的重要性，在 ROS 和 Cd 响应基因的大肠杆菌突变体中进行了实验。正如预期的那样，与野生型菌株相比，ROS 响应基因的大肠杆菌突变体对光激活的 QDs 更敏感，而在绿色-QDs 中效果更高。在与镉相关的突变体中未观察到光毒性增加。
研究结果表明，光照会增加仿生 QDs 对大肠杆菌细胞的毒性。仿生 CdTe-GSH QDs 的细菌光毒性机制主要与 ROS 的产生有关。
所提出的结果确立了仿生 CdTe-GSH QDs 作为一种有前途的具有成本效益的替代方法，可用于对抗微生物感染，尤其是 QDs 。
