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.