Yang Qingbo, Cristea Alexandre, Roberts Charles, Liu Kun, Song Yang, Xiao Hai, Shi Honglan, Ma Yinfa
Department of Chemistry, and Center for Biomedical Research, Missouri University of Science and Technology, Rolla, MO 65409, USA.
Analyst. 2020 Nov 9;145(22):7210-7224. doi: 10.1039/d0an01437k.
Single-cell analysis is an emerging research area that aims to reveal delicate cellular status and underlying mechanisms by conquering the intercellular heterogeneity. Current single-cell research methods, however, are highly dependent on cell-destructive protocols and cannot sequentially display the progress of cellular events. A recently developed pH nanoprobe in our lab conceptually showed its ability to detect intracellular pH (pHi) without cell labeling or disruption. In the present study, we took the cytotoxicity of nanoparticles (NPs) as a typical example of cell heterogeneity, to testify the practicality of the pH nanoprobe in interpreting cell status. Three types of NPs (CeO2, TiO2, and SiO2) were employed to generate varied toxic effects. Results showed that the traditional assays - including cell viability, intracellular ROS generation, and mitochondrial inner membrane depolarization - not only failed to report the nanotoxicity accurately and timely, but also drew confusing or misleading conclusions. The pH nanoprobe revealed explicit pHi changes induced by the NPs, which corresponded well with the cell damages found by the transmission electron microscopic (TEM) imaging. Besides, our results unveiled an unexpectedly devastating effect of SiO2 NPs on cells during the early stage NP-cell interaction. The developed novel pH nanoprobe demonstrated a rapid sensing capability at single-cell resolution with minimum invasiveness. Therefore, it may become a promising alternative for a wide range of applications in areas such as single-cell research and precision medicine.
单细胞分析是一个新兴的研究领域，旨在通过克服细胞间的异质性来揭示精细的细胞状态和潜在机制。然而，当前的单细胞研究方法高度依赖于细胞破坏方案，并且无法连续展示细胞事件的进展。我们实验室最近开发的一种pH纳米探针从概念上显示了其在不进行细胞标记或破坏的情况下检测细胞内pH（pHi）的能力。在本研究中，我们以纳米颗粒（NPs）的细胞毒性作为细胞异质性的一个典型例子，来验证pH纳米探针在解释细胞状态方面的实用性。使用了三种类型的NPs（CeO2、TiO2和SiO2）来产生不同的毒性效应。结果表明，传统检测方法——包括细胞活力、细胞内活性氧生成和线粒体内膜去极化——不仅未能准确及时地报告纳米毒性，还得出了令人困惑或误导性的结论。pH纳米探针揭示了由NPs诱导的明显的pHi变化，这与透射电子显微镜（TEM）成像发现的细胞损伤情况高度吻合。此外，我们的结果揭示了SiO2 NPs在早期NP-细胞相互作用过程中对细胞产生的意想不到的毁灭性影响。所开发的新型pH纳米探针在单细胞分辨率下展示了快速传感能力，且侵入性最小。因此，它可能成为单细胞研究和精准医学等广泛领域中多种应用的一个有前景的替代方案。
