ROS-cleavable diselenide nanomedicine for NIR-controlled drug release and on-demand synergistic chemo-photodynamic therapy

Many chemotherapeutic drugs and photosensitizers suffer from poor solubility, unspecific delivery and uncontrollable release, which severely impede their biomedical applications. Herein, we designed a type of ROS-cleavable hydrophilic diselenide nanoparticles through self-assembling of PEG-modified camptothecin (CPT, a hydrophobic drug) and meso‑tetra (4-carboxyphenyl) porphine (TCPP, a hydrophobic photosensitizer). The [email protected] nanomedicine (particle size: 116.5 ± 1.9 nm) has stability for long-time blood circulation. Near-infrared (NIR) laser-triggered generation of ROS from TCPP can efficiently break the ROS-sensitive diselenide bond, which induces the decomposition of [email protected] nanomedicine for concurrent release of CPT and TCPP. Moreover, the released amounts of CPT and TCPP can be regulated by adjusting the NIR laser irradiation time. Such NIR-controlled release of CPT and TCPP can give rise to on-demand synergistic chemo-/photodynamic therapeutic effects for maximized tumor growth suppression with minimized side effects. In this work, a ROS-cleavable diselenide nanoparticle was designed and successfully self-assembled with the hydrophobic drug camptothecin and photosensitizer TCPP into a hydrophilic [email protected] nanomedicine. Compared with traditional drug delivery systems, [email protected] nanomicelles could reduce premature drug release and co-deliver hydrophobic chemotherapeutic drugs/photosensitizers to tumors, which yielded a NIR-controlled synergistic chemo-/photodynamic therapeutic effect. Since diselenide bond is more sensitive than the traditional disulfide bond, under the 660 nm laser irradiation (300 mW/cm2), ROS generated from laser-excited TCPP in [email protected] nanomicelles could break the diselenium bonds to achieve the light-controlled release of CPT. In addition, the photosensitizer TCPP could also be imaged at the tumor site. Due to the photodynamic therapy from laser-excited TCPP and chemotherapy from photocontrolled release of CPT in [email protected], our designed nanomicelles yielded potent antitumor effects both in vitro and in vivo.