Enzyme-Silenced Nanosponges Prolong Intratumoral Lifetime to Facilitate Intercellular Relay Drug Delivery and Treatment Efficacy

The clinical application of nanomedicines faces the dilemma of improved safety but restricted efficacy due to the poor intratumoral bioavailability of chemotherapeutics. We here design an enzyme-silenced nanosponge that shares a long-term lifespan to reversibly exhale/inhale doxorubicin (DOX) for continuous intercellular relay delivery and improved intratumoral retention. The nanosponge is composed of a cationic lipid overlaying a hyaluronic acid derivative polyampholyte core for enveloping of DOX and hyaluronidase-1-targeted siRNA (siHyal1), and a lipoprotein shell decorated with fusion peptide 4F-tLyP-1 that was fused with apolipoprotein A-I (apoA-I) mimetic peptide 4F and tLyP-1 for tumor homing and extravasation into the tumor interstitium. Triggered by the intra/intercellular pH variation, the nanosponge core could reversibly swell in endo/lysosome (pH 5.0) for DOX release. Owing to the deprotonation, the nanosponge core shrinks back in cytoplasm (pH 7.4) for DOX reloading and continues the behavior after being secreted to the extracellular matrix (pH 6.8) via Golgi apparatus, which dramatically improves intratumoral DOX retention and availability. Concurrently, the intratumoral lifespan of the nanosponge is prolonged by siHyal1-specific silencing, ensuring spatiotemporal consistency of carrier and drug when shuttling multilayer tumor cells. As a result, the nanosponge achieves efficient tumor inhibition in 99.1% of tumor spheroids and 80.1% of orthotopic tumor models. Collectively, this study provides an intelligent nanosponge design for active intercellular relay drug delivery, achieving improved intratumoral bioavailability of drugs and amplified chemotherapy on solid tumors.