Biocompatible fluorenylphthalocyanines for one- and two-photon photodynamic therapy and fluorescence imaging

The synthesis and the optical properties of a family of new fluorenyl phthalocyanines substituted with water-solubilizing triethyleneglycol chains is described. These biocompatible molecules exhibit strong one- and two-photon absorptions, together with fluorescence and photosensitization properties similar to those of their lipophilic analogues, thus outperforming unsubstituted zinc phthalocyanine in terms of brightness and singlet oxygen production. They were subsequently probed in vitro on cancer cells under one and two-photon excitation in both fluorescence imaging and photodynamic therapy experiments. The metal-free compound was shown to be more biocompatible and thus more promising than the zinc complex for theranostic applications.