Yan Neng, Wang Yan, Wong Tin Yan, Wu Zhiwei, Wang Xiuxiu, Xie Minwei, Parodi Alessandro, Wang Wen-Xiong, Shi Jianbo
MOE Key Laboratory of Groundwater Quality and Health, School of Environmental Studies, China University of Geosciences, Wuhan 430074, China.
Department of Chemical and Biological Engineering, The Hong Kong University of Science and Technology, Kowloon 999077, Hong Kong, China.
ACS Nano. 2024 Dec 24;18(51):35013-35028. doi: 10.1021/acsnano.4c13880. Epub 2024 Dec 10.
Bioaccumulated silver nanoparticles (AgNPs) can undergo transformation and release toxic Ag, which can be further reduced and form secondary AgNPs (AgNPs). However, the intricate interconversions among AgNPs, Ag, and AgNPs remain speculative. Herein, we developed a bioimaging method by coupling the aggregation-induced emission method with the label-free confocal scattering and hyperspectral imaging techniques to quantitatively visualize the biodistribution and biotransformation of AgNPs, AgNPs, and Ag in living cells. We demonstrated that AgNPs were first dissolved in the medium, and the released Ag was converted into AgNPs with the presence of algal extracellular polymeric substances and light. Under these conditions, AgNPs alone accounted for 12.4% of the total AgNP toxicity, a percentage comparable to that of AgNPs (15.6%). However, Ag remained the primary contributor to overall AgNP toxicity. Additionally, we found that about 9.00% of the accumulated AgNPs within the algal cells were transformed after 24 h exposure. Of these transformed AgNPs, 4.70% remained as Ag forms (located in the apical region, nucleus, and pyrenoid), while 4.30% persisted as AgNP forms (located in the cytosol) that were only detectable after a 4 h exposure. We further showed that AgNP exposure upregulated algal glutathione production with a 38.3-fold increase in glutathione reductase activity, which potentially resulted in AgNP formation at the active site. Overall, this study differentiated the toxicity of AgNPs, Ag, and AgNPs and directly visualized the ongoing transformation and translocation of AgNPs, Ag, and AgNPs within living cells, which are critical in unveiling the toxicity mechanisms of AgNPs.
生物累积的银纳米颗粒（AgNPs）会发生转化并释放有毒的银，而银又可进一步还原并形成次生银纳米颗粒（AgNPs）。然而，AgNPs、银和AgNPs之间复杂的相互转化仍只是推测。在此，我们通过将聚集诱导发光法与无标记共聚焦散射和高光谱成像技术相结合，开发了一种生物成像方法，以定量可视化活细胞中AgNPs、AgNPs和银的生物分布及生物转化。我们证明，AgNPs首先溶解于培养基中，释放出的银在藻类细胞外聚合物和光照存在的情况下转化为AgNPs。在这些条件下，单独的AgNPs占总AgNP毒性的12.4%，这一比例与AgNPs（15.6%）相当。然而，银仍是总体AgNP毒性的主要贡献者。此外，我们发现，藻类细胞内积累的AgNPs在暴露24小时后约有9.00%发生了转化。在这些转化后的AgNPs中，4.70%以银的形式存在（位于顶端区域、细胞核和蛋白核），而4.30%以AgNP的形式存在（位于细胞质中），后者仅在暴露4小时后才可检测到。我们进一步表明，AgNP暴露上调了藻类谷胱甘肽的产生，谷胱甘肽还原酶活性增加了38.3倍，这可能导致在活性位点形成AgNP。总体而言，本研究区分了AgNPs、银和AgNPs的毒性，并直接可视化了活细胞内AgNPs、银和AgNPs正在进行的转化和转运，这对于揭示AgNPs的毒性机制至关重要。
