title: pH-Response Optimization of Amino-Substituted Tetraphenylporphyrin Derivatives as pH-Activatable Photosensitizers.
abstract: Amino-substituted tetraphenylporphyrin derivatives have been designed as pH-activatable photosensitizers for photodynamic cancer therapy. The photophysical processes of the monoamino-substituted derivative N1 and nonsubstituted derivative N0 have been studied. The quantum yields of the fluorescence and photosensitization of singlet oxygen by N1 were very low in the neutral condition (OFF state), but these quantum yields were recovered by adding acid (ON state). These changes were not observed for N0; therefore, N1 is expected to be applicable as a pH-activatable photosensitizer. The ON/OFF switching mechanism of N1 has also been clarified. To optimize the pH response, tri- and tetraamino-substituted derivatives (N3 and N4) have also been explored. The pH response intensified as the number of amino groups increased. Furthermore, the ON/OFF switching ratio of N3 was 100, which is quite high.
authors.affiliation: Division of Molecular Science, Graduate School of Science and Technology, and ‡International Education and Research Center for Silicon Science, Graduate School of Science and Technology, Gunma University , Kiryu, Gunma 376-8515, Japan.
authors.forename: Hiroaki
authors.initials: H
authors.lastname: Horiuchi
authors.affiliation: Division of Molecular Science, Graduate School of Science and Technology, and ‡International Education and Research Center for Silicon Science, Graduate School of Science and Technology, Gunma University , Kiryu, Gunma 376-8515, Japan.
authors.forename: Ryota
authors.initials: R
authors.lastname: Kuribara
authors.affiliation: Division of Molecular Science, Graduate School of Science and Technology, and ‡International Education and Research Center for Silicon Science, Graduate School of Science and Technology, Gunma University , Kiryu, Gunma 376-8515, Japan.
authors.forename: Atsuki
authors.initials: A
authors.lastname: Hirabara
authors.affiliation: Division of Molecular Science, Graduate School of Science and Technology, and ‡International Education and Research Center for Silicon Science, Graduate School of Science and Technology, Gunma University , Kiryu, Gunma 376-8515, Japan.
authors.forename: Tetsuo
authors.initials: T
authors.lastname: Okutsu
mesh_terms: D006863:Hydrogen-Ion Concentration; D015394:Molecular Structure; D017319:Photosensitizing Agents / Q000737:chemistry*; D011166:Porphyrins / Q000737:chemistry*; D011789:Quantum Theory
chemical_list: D017319:Photosensitizing Agents; D011166:Porphyrins; C409084:tetraphenylporphyrin