Reprogramming Photosensitization Mechanisms for Hypoxic Tumor Therapy via Organic Photovoltaic-Inspired...

Area of Science:

• Photomedicine
• Organic Photovoltaics
• Photochemistry

Background:

• Conventional Type II photodynamic therapy (PDT) efficacy is limited by tumor hypoxia.
• Organic photovoltaics (OPV) utilize charge-separation principles for efficient energy conversion.

Purpose of the Study:

• To develop a hypoxia-tolerant photodynamic therapy by re-routing photosensitizer excited-state pathways.
• To apply OPV charge-separation concepts to create a molecular donor-acceptor interface for photomedicine.

Main Methods:

• Electrostatic co-assembly of cationic Y6-2Pr with anionic Rose Bengal (RB) to form a 1:2 heterojunction.
• Investigated ultrafast intermolecular electron transfer and interfacial charge-transfer-to-charge-separated (CT → CS) evolution.
• Analyzed the redirection of Rose Bengal photochemistry towards a Type I pathway and NADH oxidation.

Main Results:

• The donor-acceptor interface significantly reduced singlet oxygen generation.
• The system promoted a hypoxia-tolerant Type I pathway, generating superoxide.
• An interfacial photoredox cycle was established, weakening intracellular reductive defenses.

Conclusions:

• Translating OPV interface concepts to photomedicine enables the creation of stoichiometrically defined molecular complexes.
• Classical Type II photosensitizers can be retrofitted with Type I photoredox function for enhanced therapeutic outcomes.
• This approach offers a promising strategy to overcome tumor hypoxia in photodynamic therapy.