The Journal of Physical Chemistry C
Heteroatom-Containing Organic Molecule for Two-Photon Fluorescence Lifetime Imaging and Photodynamic Therapy
Wenbo Hu, Qi Wang, Xiaofei Miao, Lei Bai, Lin Li, Guang S. He, Junzi Li, Song Yao, Tingchao He, Xiaomei Lu, Wei Huang, Paras N. Prasad, and Quli Fan
Two-photon fluorescence photosensitizers (TP-FPSs) with long fluorescence lifetime (τF) and high singlet oxygen quantum yield (ΦΔ) have attracted ever-growing attention as novel theranostic materials. However, to date, TP-FPSs with long τF and high ΦΔ have been rarely reported. Toward achieving this goal, we report in this study a systematic investigation of excitation dynamics in a heteroatom-containing organic molecule (3-aminophthalic acid, abbreviated as 3-APA). Our study demonstrates that 3-APA has an n-π* absorption band and two-photon absorption. Derived from n-π* transition feature, 3-APA exhibits not only a considerably long τF (11.5 ns) but also an efficient singlet-to-triplet intersystem crossing (19.2%), which leads to a high ΦΔ (18.4%). With these properties, we successfully used 3-APA as a novel TP-FPS for the proof-of-concept application in two-photon fluorescence lifetime imaging and two-photon photodynamic therapy. Notably, this work gives a better understanding of the excitation process and mechanism involved in TP-FPSs, which should be a valuable guide for constructing novel high-performing TP-FPSs.