"Turn-on" fluorescent aptasensor based on AIEgen labeling for the localization of IFN-γ in live cells

We report an aggregation-induced emission fluorogen (AIEgen)-based turn-on fluorescent aptasensor able to detect the ultrasmall concentration of intracellular IFN-γ. The aptasensor consists of an IFN-γ aptamer labeled with a fluorogen with a typical aggregation-induced emission (AIE) characteristic, which shows strong red emission only in the presence of IFN-γ. The aptasensor is able to effectively monitor intracellular IFN-γ secretion with the lowest detection limit of 2 pg mL⁻¹, and it is capable of localizing IFN-γ in live cells during secretion, with excellent cellular permeability and biocompatibility as well as low cytotoxicity. This probe is able to localize the intracellular IFN-γ at a low concentration <10 pg mL⁻¹, and it is successfully used for real-time bioimaging. This simple and highly sensitive sensor may enable the exploration of cytokine pathways and their dynamic secretion process in the cellular environment. It provides a universal sensing platform for monitoring a spectrum of molecules secreted by cells.