Modulation of phthalocyanine assembly morphology for photodynamic therapy

Abstract

Phthalocyanines (Pcs) are widely utilized as photosensitizers (PSs) in photodynamic therapy (PDT) owing to their excellent photophysical and photochemical properties, such as long-wavelength absorption, high molar extinction coefficients, and tunable characteristics via chemical modifications. By appropriately modifying the substituents of Pcs—rather than incorporating various additives—the molecular assembly morphology of Pcs can be adjusted. For instance, they can be rendered fully soluble in aqueous solutions, form switchable aggregates that recover photoactivity in the tumor microenvironment, or maintain stable aggregates while retaining photodynamic activity. Such tailored modifications would improve PDT outcomes. In this review, we summarize recent advances in water-soluble non-aggregated Pcs, switchable Pc aggregates, and stable Pc aggregates for PDT. Furthermore, we analyze the relationship between their structural features and molecular assembly morphology to provide insights for the rational design of high-performance Pc-based PSs.