Bromine Substitution Improves the Photothermal Performance of π‐Conjugated Phototheranostic Molecules
Feiyan Wan, Huan Wang, Ying Gu, Guilin Fan, Shengxin Hou, Jiantao Yu, Mengying Wang, Feng He, Leilei Tian
Abstract
Abstract NIR‐II fluorescence imaging–guided photothermal therapy (PTT) has been widely investigated due to its great application potential in tumor theranostics. PTT is an effective and non‐invasive tumor treatment method that can adapt to tumor hypoxia; nevertheless, simple and effective strategies are still desired to develop new materials with excellent PTT properties to meet clinical requirements. In this work, we developed a bromine‐substitution strategy to enhance the PTT of A‐D‐A’‐D‐A π‐conjugated molecules. The experimental results reveal that bromine substitution can notably enhance the absorptivity ( ϵ ) and photothermal conversion efficiency (PCE) of the π‐conjugated molecules, resulting in the brominated molecules generating two times more heat ( ϵ 808 nm ×PCE) than their unsubstituted counterpart. We disclose that the enhanced photothermal properties of bromine‐substituted π‐conjugated molecules are a combined outcome of the heavy‐atom effect, enhanced ICT effect, and more intense bromine‐mediate intermolecular π–π stacking. Finally, the NIR‐II tumor imaging capability and efficient PTT tumor ablation of the brominated π‐conjugated materials demonstrate that bromine substitution is a promising strategy for developing future high‐performance NIR‐II imaging‐guided PTT agents.