pH‐Dependent Cancer‐Directed Photodynamic Therapy by a Water‐Soluble Graphitic‐Phase Carbon Nitride–Porphyrin Nanoprobe

Theranostic photodynamic nanomaterials suffer from poor water solubility and nontargeted toxicity. A water-soluble graphitic-phase carbon nitride-based material (g-C3N4) conjugated to a positively charged porphyrin P2 (conjugating concentration: 60 μm mg−1 mL−1) is shown to be a new concept of photodynamic therapeutic agent (g-C3N4–P2). The pH-sensitive emission of g-C3N4 is the driving force for the generation of 1O2 from g-C3N4–P2. The amount of 1O2/light generated from a photosensitizer porphyrin can be controlled by the pH-sensitive emission of g-C3N4 at acidic pH (pH 4–6), especially under acidic conditions mimicking those of tumor tissue, and thus has the potential to be utilized as a cancer-selective PDT agent.