Multifunctional aggregation-induced emission nanoparticle for high-fidelity imaging of lipid droplets in living cells and its application in photodynamic therapy

Near-infrared (NIR) aggregation-induced emission (AIE) nanomaterials, with organelles targeted-imaging ability and effective reactive oxygen species (ROS) generation nature, are highly desirable photosensitizers (PSs) for fluorescence imaging-guided photodynamic therapy (PDT), but it remains challenging. Herein, a NIR AIE luminogens (AIEgens, TTI) was designed and synthesized using three-fragmentary assembly molecular engineering, which was used for intracellular lipid droplets (LDs) high-fidelity dynamic tracking (Pearson's coefficient of 0.95) due to its strong lipophilic nature (ClogP of 8.34), large Stokes shifts (170 nm), excellent photostability and good biocompatibility. Meanwhile, TTI self-assembled nanoparticles with an average diameter of 196.57 nm exhibited extremely high-efficient singlet oxygen (1O2) generation efficiency (with up to 85.16% of quantum yield) in PBS solution. In addition, the TTI as a desired PS revealed good phototoxicity for living HepG2 cells under white light irradiation. Moreover, the live/dead cells co-staining image, flow cytometry and scratch wound healing assays indicated that TTI could effectively inhibit the proliferation and cause/induce cells apoptosis, which eventually led to the death of HepG2 cells. Therefore, this work provides a useful strategy for LDs-targeting molecular engineering and highlights the potential of organic nanoparticles PSs drug in biomedical and fluorescence imaging-guided PDT fields.