Persistent luminescence-activated Janus nanomotors with integration of photodynamic and photothermal cancer therapies

Abstract

Cancer photothermal (PTT) and photodynamic therapies (PDT) have aroused tremendous attention with high spatial specificity, but they experience the challenges from the inefficient tumor accumulation and penetration of photosensitizers and dose-dependent side effects. Herein, persistent luminescence (PL)-activated nanomotors are developed with the integration of PL-illuminated PTT and PDT to overcome these limitations. PL nanodots of ZnGa2O4:Cr3+ (ZGC) were deposited on mesoporous silica nanoparticles (NPs), followed by conjugation of silicon phthalocyanine as a photosensitizer and capping with polydopamine (PDA) to fabricate Janus mPL-Pc@PDA NPs. ZGC nanodots on NPs are activated by external illumination to generate PL as an internal light source to excite PDA and phthalocyanine for persistent productions of heat and reactive oxygen species (ROS), avoiding high heat stress and ROS levels in the conventional intermittent phototherapy. In addition, the persistent heat gradients around the Janus NPs create thermophoretic force to drive their motions and enhance their cellular uptake, and the PL-illuminated PDT continuously produces intracellular ROS to damage tumor cells. Light activation of mPL-Pc@PDA obviously promotes accumulation and deep penetration of NPs into tumors and produces mild thermal and ROS levels with well distribution across the tumors. The self-propelled tumor distribution and the combined PDT/PTT treatment led to full inhibition of tumor growth and significant extension of animal survival, and there is no systemic toxicity and function fluctuation of the major organs. Thus, this study demonstrates a concise strategy to generate PL-activated motion for deep penetration and produce PL-illuminated PDT/PTT for synergistic tumor treatment.