Ultrasound-powered hydrogen peroxide-responsive Janus micromotors for targeted thrombolysis and recurrence inhibition

Thrombosis seriously endangers human health with high incidence and mortality worldwide, and the clinical treatment is challenged by low bioavailability of thrombolytic agents, high bleeding risk and thrombosis relapse. Herein, ultrasound-powered Janus micromotors with stimuli-responsive multiple release capabilities are developed for efficient thrombolysis and inhibition of thrombosis recurrence. Resveratrol-loaded hyaluronic acid (HARes) nanoparticles (NPs) and urokinase plasminogen activator (uPA) were entrapped into H2O2-sensitive poly(1,4-cyclohexanedimethanol-co-oxalate) (POX) microparticles (MPs), followed by polydopamine capping and RGD grafting to obtain Janus rJPox@u-HARes MPs. After RGD-mediated delivery to the thrombus site, the peroxalate ester bonds of POX are oxidized by the elevated H2O2 to produce CO2, and the MP collapse accelerates the local release of uPA and HARes NPs. The resulting CO2 bubbles amplify the cavitation effect of ultrasound to promote thrombus penetration and site-specific uPA thrombolysis. The endothelial cell targeting and sustained resveratrol release from HARes NPs dramatically improve endothelial cell viability, nitric oxide production and migration. Compared with free drug administration, the uPA loading into MPs significantly extends the half-life (15 folds) and bioavailability (7 folds), while the resveratrol inoculation into NPs increases the bioavailability 29 times. On an acute lower limb thrombosis model, the thrombus accumulation of MPs is promoted by RGD-mediated interactions with the activated platelets and ultrasound-driven penetration into thrombi, leading to almost full removal of blood clots. The H2O2-scavenging capability of POX, sustained resveratrol release and efficient thrombolysis alleviate oxidative stresses, eliminate coagulation biomarkers and repair the damaged endothelial layer to effectively inhibit thrombosis relapse. It is demonstrated that rJPox@u-HARes/US treatment could not only achieve safe and site-specific thrombolytic therapy at the early stage but also restore vascular homeostasis to effectively prevent thrombosis recurrence.