Molecular Motion in Aggregates: Manipulating TICT for Boosting Photothermal Theranostics

作者：Shunjie Liu, Xin Mu Zhou, Haoke Zhang, Hanlin Ou, Jacky W. Y. Lam, Yang Liu, Linqi Shi, Dan Ding, Ben Zhong Tang · 发表于：Journal of the American Chemical Society · 年份：2019 · DOI：10.1021/jacs.8b13889 · 被引用次数：662 · 研究领域：Nanoplatforms for cancer theranostics、Luminescence and Fluorescent Materials、RNA Interference and Gene Delivery

Planar donor and acceptor (D-A) conjugated structures are generally believed to be the standard for architecting highly efficient photothermal theranostic agents, in order to restrict intramolecular motions in aggregates (nanoparticles). However, other channels of extra nonradiative decay may be blocked. Now this challenge is addressed by proposing an "abnormal" strategy based on molecular motion in aggregates. Molecular rotors and bulky alkyl chains are grafted to the central D-A core to lower intermolecular interaction. The enhanced molecular motion favors the formation of a dark twisted intramolecular charge transfer state, whose nonradiative decay enhances the photothermal properties. Result shows that small-molecule NIRb14 with long alkyl chains branched at the second carbon exhibits enhanced photothermal properties compared with NIRb6, with short branched chains, and much higher than NIR6, with short linear chains, and the commercial gold nanorods. Both in vitro and in vivo experiments demonstrate that NIRb14 nanoparticles can be used as nanoagents for photoacoustic imaging-guided photothermal therapy. Moreover, charge reversal poly(β-amino ester) makes NIRb14 specifically accumulate at tumor sites. This study thus provides an excited molecular motion approach toward efficient phototheranostic agents.