A ruthenium(II) based photosensitizer and transferrin complexes enhance photo-physical properties, cell uptake, and photodynamic therapy safety and efficacy

Metal-based photosensitizers are of interest as their absorption and chemical binding properties can be modified via the use of different ligands. Ru2+ based photosensitizers are known to be effective photodynamic therapy (PDT) agents against bacteria, whereas use for oncological indications in vivo has not been demonstrated with the same level of evidence. We present data showing that premixing the Ru2+-complex TLD1433 with transferrin increases the molar extinction coefficient, including longer activation wavelengths, reduces photobleaching rates, and reduces the toxicity of the complex improving overall PDT efficacy. As the transferrin receptor is upregulated in most malignancies, premixing the Ru2+ complex with transferrin converts the active pharmaceutical ingredient TLD1433 into a drug of potentially considerable clinical utility.