An Effective Supramolecular Approach to Boost the Photodynamic Therapy Efficacy of a Near-Infrared Activating Perylene Diimide-Based Photosensitizer

Perylene diimide (PDI) derivatives with outstanding photo-physicochemical properties hold significant promise for application in solar energy conversion, pollutant degradation, and disease diagnosis. However, the inherent characteristics of PDI molecules, including poor water solubility, short-wavelength absorption, and negligible singlet oxygen ( 1 O 2 ) generation capabilities, severely limit their application in photodynamic therapy (PDT). Here, a novel PDI-based photosensitizer was deliberately designed with the potential to solve these limitations. By facile modifications of a PDI molecule, we constructed an amphiphilic PDI-based compound (PDIPa) that can be self-assembled into a functional supramolecular photosensitizer (NanoPDIPa) with excellent water dispersity and intense near-infrared (NIR) absorbance. Remarkably, the intermolecular electronic coupling and interaction in NanoPDIPa can induce efficiency intersystem crossing (ISC) through the minimization of singlet–triplet energy gap (Δ E ST ), a characteristic that is not possessed by the monomer, thus resulting in significant 1 O 2 production. The successful development of NanoPDIPa not only can enlarge the family of NIR-absorbing photosensitizers for potential PDT applications but also can provide a solution to overcome the limitations of clinically used photosensitizers.