Cleavable collagenase-assistant nanosonosensitizer for tumor penetration and sonodynamic therapy

Sonodynamic therapy (SDT), a combination of low-intensity ultrasound with a sonosensitizer, has been explored as a promising alternative for cancer therapy. However, condensed extracellular matrix (ECM) resulting in poor perfusion and extreme hypoxia in solid tumor potentially compromises effective SDT. Herein, we develop a novel cleavable collagenase-assistant and O₂-supplied nanosonosensitizer (FePO₂@HC), which is embedded through fusing collagenase (CLG) and human serum albumin (HSA), followed by encapsulating Ferric protoporphyrin (FeP) and dioxygen. As a smart carrier, HSA is stimuli-responsive and collapsed by reduced glutathione (GSH) overexpressed in tumor, resulting to the release of the components in FePO₂@HC. The released CLG acting as an artificial scissor, degrades the collagen fibers in tumor, thus, breaking tumor tissue and enhancing FePO₂ accumulation in tumor inner with higher than that without CLG. Simultaneously, oxygen molecules are released from FePO₂ in hypoxic environment and alleviate the tumor hypoxia. As a sonosensitizer, FeP is subsequently irradiated by ultrosound wave (US) and activates surrounding dioxygen to generate amount of singlet oxygen (¹O₂). Contributed from the ECM-degradation, such SDT-based nanosystem with increased sonosensitizer permeability and oxygen content highly improved the tumor inhibition efficacy without toxic effects. This study presents a new paradigm for ECM depletion-based strategy of deep-seated penetration, and will expand the nanomedicine application of metalloporphyrin sonosensitizers in SDT.