Bioorthogonal-Inspired In Situ Hydrogel for Nattokinase-Assisted Enhancement of Photothermal-Chemotherapy of Tumors

Conventional chemotherapy is often limited by the physical tumor microenvironment, where an elevated interstitial pressure and dense extracellular matrix collectively impair drug penetration, reduce targeting efficiency, and lead to systemic toxicity. To address these challenges, we proposed an in situ synergistic therapeutic strategy combining nattokinase (NKase) pretreatment with a bioorthogonal chemistry-inspired hydrogel (CuPP@PH). Intratumorally injected NKase effectively reduced tumor stiffness and markedly increased local blood perfusion. Subsequently, the CuPP@PH was rapidly formed in situ via dynamic boronate ester cross-linking between the Copper-functionalized Prussian blue nanozymes (CuPP NZs) and phenylboronic-grafted hyaluronic acid (PH). The embedded CuPP NZs demonstrated significant multienzyme mimetic activity, substantially enhancing photothermal ablation efficacy. Specifically, the CuPP@PH further eradicated residual tumor cells by facilitating the in situ synthesis of cytotoxic copper diethyl dithiocarbamate (CuET) complex from prolonged-retention CuPP NZs and orally administered disulfiram. This work establishes a bioorthogonal-inspired combinatorial strategy that augments in situ chemotherapy and photothermal therapy through remodeling the tumor physical microenvironment.