Building Single-Color AIE-Active Reversible Micelles to Interpret Temperature and pH Stimuli in Both Solutions and Cells

Interpreting macroscopic stimulus into visible signals with nanomaterials is crucial for the development of smart nanoprobes for in situ monitoring or imaging. Building nanoprobes to translate pH and temperature stimuli into a single-color signal with a "turn-on" feature is a great challenge. Here, we aim to interpret temperature and pH stimuli into a single-color signal via aggregation-induced emission (AIE) active reversible micelles. The dual-responsive block copolymers, PNIPAM-b-P(DPA-co-TPE) and P(NIPAM-co-TPE)-b-PDPA, were conveniently prepared with similar block length but different TPE position through reversible addition–fragmentation chain-transfer (RAFT) polymerization. Both dual-responsive polymers could self-assemble into reversible micelles with AIE-active turn-on fluorescence under the stimulus of pH or temperature, respectively. The fluorescence intensity enhanced 7-fold for PNIPAM-b-P(DPA-co-TPE) and 3-fold for P(NIPAM-co-TPE)-b-PDPA by tuning the solution pH or temperature, which further showed a robust "on–off" reversibility of fluorescence signal. Through coassembly, the stimulus of either pH or temperature could be identified based on the different intensity and expansion of the emission spectra, which was further confirmed in vitro for cell imaging. Definitely, this work provides a promising approach to interpret minor pH or temperature changes in solutions and in cells.