Improved photodynamic activity of a dual phthalocyanine–ALA photosensitiser

A phthalocyanine–ALA conjugate showed an improved photoinduced cell killing efficiency due to the combined action of the phthalocyanine core and protoporphyrin IX, which was biosynthesised intracellularly by using released ALA as a substrate. The intracellular presence of two photosensitisers and their joint excitation induced a synergistic efficiency for cell killing. The construction of photosensitisers that release intracellular ALA holds great potential for the development of more efficient PDT photosensitisers.