AIE-based dual-ratiometric chemosensor for detection of sulfur dioxide derivatives and viscosity and its application in food samples and biological imaging.

Background: SO is an important gas molecular messenger that participates in many physiological activities and helps maintaining the redox homeostasis in biological system. Especially, SO can effectively regulate oxidative stress and improve mitochondrial morphology. Abnormal mitochondrial viscosity can lead to a variety of diseases. Therefore, it is of great importance to detect SO derivatives and cell viscosity in biological systems.

Results: Here, two mitochondria-targeted and dual-ratiometric chemosensors (TPE-1 and TPE-2) based on tetraphenylethene were constructed, which could be used to simultaneously detect SO derivatives and cell viscosity. Notably, TPE-2 as the preferable due to its superior discernibility to HSO than that of TPE-1. Moreover, TPE-2 featured rapid response, high sensitivity, excellent selectivity, and low cytotoxicity under physiological conditions which means that TPE-2 is more suitable for practical application than TPE-1. The response mechanism of TPE-2 for HSO was confirmed by the theoretical calculation and mass spectral analysis. Meanwhile, TPE-2 showed enhanced fluorescence intensity the increased viscosity environment due to it was subjected to structural rotation. In addition, the practical application for detecting HSO in real water samples was successfully carried out with good recovery, the test strips loaded TPE-2 was prepared and the detection of HSO in food samples was realized by a convenient smartphone analysis. Importantly, TPE-2 had good mitochondrial targeting ability and had successfully imaged HSO and viscosity in HeLa cells and zebrafish.

Significance: This study provides an effective and potential tool for detecting HSO and viscosity in mitochondria and in vivo, the rational design strategy in this work holds potential to inspire the development of more powerful dual-response chemosensor for other biological factors.