posted on 2020-03-16, 19:13authored byMing Chen, Xiaoyan Zhang, Junkai Liu, Feng Liu, Ruoyao Zhang, Peifa Wei, Haitao Feng, Mei Tu, Anjun Qin, Jacky W. Y. Lam, Dan Ding, Ben Zhong Tang
Development
of highly effective approaches to desirable photothermal
conversion agents is particularly valuable. Herein, we report a concept,
namely, bond stretching vibration-induced photothermy, that serves
as a mechanism to construct advanced photothermal conversion agents.
As a proof-of-concept, two compounds (DCP-TPA and DCP-PTPA) with donor–acceptor
(D–A) structures were synthesized. The bond stretching vibration
of the pyrazine-containing unit in these molecules is vigorous and
insensitive to the external environmental restraint, which efficiently
transforms the absorbed photons to dark-state heat energy. The nanoparticles
(NPs) of DCP-TPA and DCP-PTPA show rather high photothermal conversion
efficiency (52% and 59%) and stronger photoacoustic (PA) signal than
commercial methylene blue and reported high-performance semiconducting
polymer nanoparticles. The DCP-PTPA NPs perform better than DCP-TPA
NPs in terms of photothermal conversion, PA signal production, and in vivo PA tumor imaging because of the increased bond stretching
vibration in the former molecule.