In recent years, the use of aggregation-induced emission luminogens (AIEgens) for biological imaging and phototherapy has become an area of intense research. However, most traditional AIEgens suffer from undesired aggregation in aqueous media with “always on” fluorescence, or their targeting effects cannot be maintained accurately in live cells with the microenvironment changes. These drawbacks seriously impede their application in the fields of bio-imaging and antitumor therapy, which require a high signal-to-noise ratio. Herein, we propose a molecular design strategy to tune the dispersity of AIEgens in both lipophilic and hydrophilic systems to obtain the novel near-infrared (NIR, ∼737 nm) amphiphilic AIE photosensitizer (namedTPA-S-TPP) with two positive charges as well as a triplet lifetime of 11.43 μs. The synergistic effects of lipophilicity, electrostatic interaction, and structure-anchoring enable the wider dynamic range of AIEgenTPA-S-TPPfor mitochondrial targeting with tolerance to the changes of mitochondrial membrane potential (ΔΨm). Intriguingly,TPA-S-TPPwas difficult for normal cells to be taken up, indicative of low inherent toxicity for normal cells and tissues. Deeper insight into the changes of mitochondrial membrane potential and cleaved caspase 3 levels further revealed the mechanism of tumor cell apoptosis activated by AIEgenTPA-S-TPPunder light irradiation. With its advantages of low dark toxicity and good biocompatibility, acting as an efficient theranostic agent,TPA-S-TPPwas successfully applied to kill cancer cells and to efficiently inhibit tumor growth in mice. This study will provide a new avenue for researchers to design more ideal amphiphilic AIE photosensitizers with NIR fluorescence.
Bibliographical noteFunding Information:
J. Y. thanks the National Research Foundation of Korea (NRF) funded by the Korean government (MSIP) (No. 2012R1A3A2048814). X. P. acknowledges the support from the National Natural Science Foundation of China (No. 22090011). We thank Haoying Ge from Dalian University of Technology and the NICESCI Open Access Graph for help with the schematic design.
© The Royal Society of Chemistry 2021.