Color-tunable AIE-active conjugated polymer nanoparticles as drug carriers for self-indicating cancer therapy via intramolecular FRET mechanism

In this paper, two novel AIE-active conjugated polymers were synthesized by Pd-catalyzed Suzuki coupling polymerization reaction. Interestingly, the obtained conjugated polymers could exhibit clear color-tunable AIE behavior by adjusting their intramolecular FRET pairs. Among them, P-1 with only one intramolecular FRET pair exhibited clear green-colored AIE fluorescence. As the second intramolecular FRET pair of a TPE moiety and a DTBT moiety was added (P-2), the AIE fluorescence color could be tuned from green to red. The Stokes shift also sharply increased from 125 nm to 255 nm. Furthermore, these AIE-active polymers could form stable conjugated polymer nanoparticles (CPNs) in an aqueous system and act as drug carriers for paclitaxel (PTX). Most importantly, PTX could be sufficiently released from these AIE-active CPNs and showed effective cytotoxicity on HeLa and A549 cells. Especially, these two AIE-active drug carriers were internalized by cells, and they also revealed their location with green or red colored AIE fluorescence. This study can provide a novel strategy for designing color-tunable AIE-active CPN-based drug carriers for self-indicating cancer therapy via changing intramolecular FRET pairs.