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 mu m 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 O-1(2) from g-C3N4-P2. The amount of O-1(2)/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.