Multifunctional nanomicelles constructed by aggregation and de-aggregation strategy for magnetic resonance/NIR II fluorescence imaging guided Type I photodynamic therapy

Fluorescence and magnetic resonance imaging (FL/MRI) has received much attention from their complementary characteristics. However, the simultaneous enhancement of fluorescence and MR signals plus the efficacy of the treatment is still a major challenge. To solve this problem, we put forward a strategy of aggregation and de-aggregation based on aggregation-induced emission (AIE). NIR II photosensitizer TQ-TPA with Type I reactive oxygen species (ROS) generation ability and an amphiphilic 2TPE-Gd were firstly synthesized, and both of them showed the AIE property. Depending on the hydrophilic properties, hydrophobic TQ-TPA spontaneously aggregated into the core of nanomicelles formed by DSPE-PEG. Meanwhile, the aggregated 2TPE-Gd in aqueous solution could de-aggregate and insert in the interface, and formed TGdTT NMs. Based on this strategy and AIE property, TGdTT NMs exhibited strong NIR II fluorescence emission and Type I ROS generation ability, and enhanced T1 relaxivity (r1). Moreover, in vitro, in vivo, and pharmacokinetics results demonstrated these nanomicelles had good biosafety and long blood circulation time. Finally, they successfully realized complementary MR/NIR II fluorescence dual-modal imaging guided photodynamic therapy (PDT) to inhibit tumor growth. This work demonstrated that aggregation and de-aggregation strategy of AIEgens in the core-shell nanomicelle exudes infinite charm for constructing the multifunctional theranostic probes.