Heavy atom effect on water-soluble porphyrin photosensitizers for photodynamic therapy

Porphyrin and its derivatives have become the second-generation photosensitizers for photodynamic therapy (PDT). Three water-soluble porphyrins containing halogen atoms (F, Cl, Br) were synthesized by N-pyridyl substituted alkylation reaction. We found that P3 has the highest singlet oxygen generation capacity and the results of density functional theory (DFT) further support this result. MTT assay was used to study cytotoxicity, which proved that P1-P3 have good phototoxicity and high selectivity. Fluorescence imaging and intracellular reactive oxygen species illustrate cell apoptosis and reactive oxygen species (ROS) production. High ROS production, excellent phototoxicity ensure that photosensitizers become potential candidates for PDT drugs.