Sulfonate-Functionalized AlEgens: Strategic Approaches Beyond Water Solubility for Sensing and Imaging Applications

The development of water-soluble aggregation-induced emission (AIE)-active light-up probes for sensing and imaging purposes has drawn immense research attention in the recent past. One strategy has been to introduce SO3 groups in AlEgens (AIE-sulfonates) to increase their hydrophilic properties, and the ionic nature of the corresponding compounds also paves the way for electrostatic interaction with various analytes, in particular, with several biospecies having positively charged surfaces. A significant number of AIE-sulfonates, many among them having a tetraphenylethylene (TPE) moiety, have been designed and synthesized for the selective detection of a variety of analytes, such as metal ions, small molecules, enzymes, proteins, and bacteria. The strategies for selective detection include, for example, spontaneous complex formation with cations, electrostatic interaction with target-specific units in the biospecies, and strong hydrophobic interactions. In addition, these AlEgens are used in cell imaging and OLED applications. This Review attempts to provide a summary and discuss recent developments in sulfonate-functionalized AIE-active light-up probes in sensing and imaging applications with a focus on the role of the sulfonate functionality in the design and sensing processes.

Automated summary

The development of water-soluble aggregation-induced emission (AIE)-active light-up probes for sensing and imaging purposes has drawn significant research attention. Introducing SO3 groups in AlEgens (AIE-sulfonates) increases their hydrophilic properties and allows for electrostatic interaction with various analytes, particularly with biospecies having positively charged surfaces. These AIE-sulfonates, including those with a tetraphenylethylene (TPE) moiety, have been designed and synthesized for selective detection of analytes and are also used in cell imaging and OLED applications.