Bromine Substitution Improves the Photothermal Performance of π‐Conjugated Phototheranostic Molecules

• Published in: Chemistry : a European journal 2024-01, Vol.30 (5), p.e202303502-n/a
• Main Authors: Wan, Feiyan, Wang, Huan, Gu, Ying, Fan, Guilin, Hou, Shengxin, Yu, Jiantao, Wang, Mengying, He, Feng, Tian, Leilei
• Format: Article
• Language: English
• Subjects: Absorptivity; Bromination; Bromine; Bromine - therapeutic use; bromine substitution; Cell Line, Tumor; Chemistry; Humans; Hypoxia; Imaging; Nanoparticles; Neoplasms - drug therapy; Neoplasms - therapy; NIR-II fluorescence imaging; Phototherapy; Photothermal conversion; Photothermal Therapy; pi-conjugated molecules; Precision medicine; Substitutes; Theranostic Nanomedicine - methods; tumor treatment; Tumors
• ISSN: 0947-6539; 1521-3765
• DOI: 10.1002/chem.202303502

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 (ϵ808 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. Bromine substitution enhances the photothermal properties of π‐conjugated phototheranostic molecules; this is the outcome of a combination of the heavy‐atom effect, enhanced ICT effect, and more intense bromine‐mediate intermolecular π–π stacking. The results demonstrate that bromine substitution is promising for developing high‐performance NIR‐II imaging‐guided photothermal agents.