High payload nanoparticles composed of 7-ethyl-10-hydroxycamptothecin and chlorin e6 for synergistic chemo-photodynamic combination therapy

Combined chemo-photodynamic therapy strategy is regarded as a potential strategy for advanced cancer treatments. Herein, novel high payload 7-ethyl-10-hydroxycamptothecin (SN38)/chlorin e6 (Ce6) NPs based on the collaborative assembly of the pre-obtained SN38–Ce6 complex and biocompatible amphiphilic block polymer DSPE-PEG2000 were successfully constructed. The self-assembly mechanism of the NPs was corporately disclosed as static quenching resulted from complex formation between DSPE-PEG2000 and the pre-acquired SN38–Ce6 complex via fluorescence quenching experiment. The high payload SN38/Ce6 NPs exhibited uniform rod-like morphology with a hydrodynamic radius of about 200 nm, a zeta potential of around −25 mV, and excellent storage stability. The high payload NPs showed efficient singlet oxygen generation capacity both in tube and in murine mammary carcinoma (4T1) cells under laser irradiation. Moreover, the in vitro cytotoxicity and in vivo antitumor efficacy of the NPs (with laser) against 4T1 cell lines model were proved to be statistically significant compared to CPT-11 injection and single-drug NPs due to synergistic chemo-photodynamic therapy and high cellular uptake efficiency. Meanwhile, the systemic toxicity of the NPs was basically absent. Conclusively, the high payload dual-functional nanoparticles could be served as a promising strategy for cancer treatment in clinic.