An AceDAN–porphyrin(Zn) dyad for fluorescence imaging and photodynamic therapy via two-photon excited FRET

Abstract

The recent development of the two-photon technique offers a unique opportunity to improve the depth of imaging and treatment in photodynamic therapy (PDT). Herein, we designed a fluorescence resonance energy transfer (FRET) based AceDAN–porphyrin(Zn) dyad for two-photon excited fluorescence imaging and PDT of cancer cells simultaneously, in which the AceDAN moiety was selected as the two-photon absorption donor and the porphyrin(Zn) moiety served as the energy acceptor. Upon one-photon or two-photon excitation, the excited state energy of the AceDAN donor was transferred to the porphyrin(Zn) acceptor with high efficiency (η_EET = 98%), where red fluorescence and singlet oxygen were generated. Dyad 1 exhibited high photocytotoxicity towards A549 cells (IC₅₀ = 4.3 μM) with rapid cellular uptake while displaying low dark-cytotoxicity. Furthermore, by combining the advantages of two-photon excitation with a porphyrin(Zn) photosensitizer, the AceDAN–porphyrin(Zn) dyad has been successfully applied to A549 cells for imaging and photodynamic therapy under two-photon laser irradiation.