A versatile Pt-Ce6 nanoplatform as catalase nanozyme and NIR-II photothermal agent for enhanced PDT/PTT tumor therapy

Abstract

The hypoxic nature of solid tumors has severely negative effects on oxygen-based photodynamic therapy. In this study, we used porous Pt nanoparticles as a catalase (CAT) nanozyme, the second near-infrared (NIR-II) region photothermal transition agents (PTAs), and carriers of photosensitizer chlorin e6 (Ce6) to synthesize a composite nanosystem Pt-Ce6. In this system, Pt-Ce6 can continuously and stably decompose H2O2 into oxygen, thereby alleviating tumor hypoxia and improving the effect of photodynamic therapy (PDT). With 650 nm illumination, the reactive oxygen species (ROS) produced by Ce6 will decrease the mitochondrial membrane potential (MMP, ΔΨm) to release cytochrome c (Cyt-c) from the mitochondria into the cytoplasm, eventually leading to mitochondrial-mediated cellular apoptosis during the PDT process. In addition, Pt-Ce6 has good photothermal stability and high photothermal conversion efficiency (52.62%) in the NIR-II region. In U14 tumor-bearing mice, Pt-Ce6 completely suppressed tumor growth and recurrence under laser irradiation. Thus the nanocomposite shows excellent PDT/photothermal therapy (PTT) synergistic performance in vitro and in vivo.