ICG-ALA Complex for Improved Phototherapy of Cancer

5-Aminolevulinic acid (ALA) based photodynamic therapy (PDT) is a clinically approved therapeutic method for cancer treatment. Indocyanine green (ICG) is on the other hand an FDA-approved fluorescent dye that has been used in medical imaging in the near-infrared (NIR), and recognized as an agent to induce photothermal therapy (PTT). However, the hydrophilicity of ALA and rapid degradation of ICG in aqueous or physiological media as well as their instability limit their application. Besides, the combination of PDT and PTT is a promising alternative to single therapy. Herein, electrostatic binding of ALA to ICG is proposed to bypass such handicaps and provide enhanced therapeutic outcomes with simultaneous PDT and PTT combination. ICG-ALA exhibited excellent biocompatibility and when treatment coupled with 640/808 nm 5 min co-irradiation caused significantly stronger phototoxicity at very low concentrations. ICG-ALA demonstrates visualization of cancer cells in both NIR (ICG) and visible (PpIX) regions allowing imaging-guided phototherapy.