Photothermal-responsive Prussian blue nanocages loaded with thrombin for tumor starvation therapy and photothermal therapy.

The goal of inhibiting tumor growth can be achieved by cutting off the supply of nutrients in the blood vessels of a tumor site, but finding ways to effectively, accurately and safely deliver drugs that can induce vascular embolism remains a challenge. Phase change materials (PCM) can undergo solid-liquid transformation at the phase change temperature. This study reports on a near-infrared ray (NIR)-responsive nano-drug delivery platform based on Prussian blue (PB) nanoparticles. The PCM (lauric acid) can encapsulate thrombin (Thr) in the Prussian blue nanocage (PB Cage), and effectively avoid the pre-leakage of Thr during blood circulation. When the (Thr/PCM)@PB Cage is accumulated at the tumor site and irradiated with NIR, the thermal effect induced by the PB Cage causes the PCM to undergo a solid-liquid state transition, rapidly releasing the encapsulated Thr and inducing coagulation in the tumor blood vessels. Based on the safe delivery and precisely controlled release of Thr, the proliferation of tumor cells can be inhibited without damaging other tissues and organs. In addition, PB Cage-induced photothermal therapy can also ablate tumor cells. Thr-induced "starvation therapy" based on PB Cage loading provides a good reference for precise controlled-release drug delivery systems.