Nanostructured Phthalocyanine Assemblies with Efficient Synergistic Effect of Type I Photoreaction and Photothermal Action to Overcome Tumor Hypoxia in Photodynamic Therapy

Abstract

Most photodynamic therapy (PDT) paradigms work through the highly O₂-dependent type II photoreaction to generate singlet oxygen (¹O₂). The hypoxic microenvironment of solid tumors severely hampers therapeutic outcomes. Here, we present a novel design that could transfer the photophysical and photochemical properties of traditional phthalocyanine-based photosensitizers from type II photoreaction to efficient type I photoreaction and vibrational relaxation-induced photothermal conversion. These features enable the obtained nanostructured phthalocyanine assemblies (e.g., NanoPcAF) to display excellent phototherapies under both normoxic and hypoxic conditions. Moreover, NanoPcAF has a high level of accumulation in tumor tissues after intravenous injection, and 94% of tumor growth is inhibited in a preclinical model at a NanoPcAF dose of 0.8 nmol g^-1 and light dose of 300 J cm^-2.