Leveraging Steric Hindrance Engineering in Conjugated Polymers for Enhanced NIR-II Fluorescence Imaging and High-efficiency Photothermal Therapy

Bin Chang; Chen-Hang Xi; Zi-Kun Yu; Zi-Xin Hu; Peng-Fei Chen; Qu-Li Fan; Peng-Fei Sun

doi:10.1007/s10118-026-3868-2

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Leveraging Steric Hindrance Engineering in Conjugated Polymers for Enhanced NIR-II Fluorescence Imaging and High-efficiency Photothermal Therapy

RESEARCH ARTICLE | Updated：2026-11-11

- Leveraging Steric Hindrance Engineering in Conjugated Polymers for Enhanced NIR-II Fluorescence Imaging and High-efficiency Photothermal Therapy
- Chinese Journal of Polymer Science Vol. 44, Pages: 1-9(2026)
- Affiliations：
  
  a.State Key Laboratory of Flexible Electronics & Institute of Advanced Materials (IAM), Jiangsu Key Laboratory for Biosensors, Nanjing University of Posts & Telecommunications, Nanjing 210023, China
  b.Huangshan Technology Innovation Center for Green Chemical Engineering and New Materials, School of Chemistry and Chemical Engineering, Huangshan University, Huangshan 245041, China
  c.State Key Laboratory of Coordination Chemistry, School of Chemistry and Chemical Engineering, Nanjing University, Nanjing 210023, China
- Author bio：
  
  iampfsun@njupt.edu.cn (P.F.C.)
  pfchen@hsu.edu.cn (P.F.S.)
- Funds：
- DOI：10.1007/s10118-026-3868-2
  CLC：
- Received：29 June 2026，
  
  Accepted：28 August 2026，
  
  Online First：11 November 2026，
  
  Published：2026-10
- Accepted：
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Chang, B.; Xi, C. H.; Yu, Z. K.; Hu, Z. X.; Chen, P. F.; Fan, Q. L.; Sun, P. F. Leveraging steric hindrance engineering in conjugated polymers for enhanced NIR-II fluorescence imaging and high-efficiency photothermal therapy. Chinese J. Polym. Sci. https://doi.org/10.1007/s10118-026-3868-2

Bin Chang, Chen-Hang Xi, Zi-Kun Yu, et al. Leveraging Steric Hindrance Engineering in Conjugated Polymers for Enhanced NIR-II Fluorescence Imaging and High-efficiency Photothermal Therapy[J/OL]. Chinese Journal of Polymer Science, 2026, 441-9.
Chang, B.; Xi, C. H.; Yu, Z. K.; Hu, Z. X.; Chen, P. F.; Fan, Q. L.; Sun, P. F. Leveraging steric hindrance engineering in conjugated polymers for enhanced NIR-II fluorescence imaging and high-efficiency photothermal therapy. Chinese J. Polym. Sci. https://doi.org/10.1007/s10118-026-3868-2 DOI：

Bin Chang, Chen-Hang Xi, Zi-Kun Yu, et al. Leveraging Steric Hindrance Engineering in Conjugated Polymers for Enhanced NIR-II Fluorescence Imaging and High-efficiency Photothermal Therapy[J/OL]. Chinese Journal of Polymer Science, 2026, 441-9. DOI： 10.1007/s10118-026-3868-2.

摘要

Abstract

The aggregation-caused quenching (ACQ) effect severely limits the fluorescence quantum yield of conventional conjugated polymers in the second near-infrared window (NIR-II). Herein

we propose an innovative steric hindrance regulation strategy by precisely controlling the topological position of alkyl side chains on acceptor units to disrupt the backbone planarity. Two donor-acceptor polymers

PBIQ and PBOQ

were synthesized

via

Stille coupling. PBIQ

featuring internal alkyl chains on the thiophene ring

exhibited remarkable aggregation-induced emission (AIE) characteristics and significantly suppressed ACQ. The prepared PBIQ nanoparticles (NPs) demonstrated high-performance NIR-II fluorescence imaging and a high signal-to-background ratio. Remarkably

under 808 nm laser irradiation

PBIQ NPs achieved an ultrahigh photothermal conversion efficiency of 70.51%

outperforming most reported organic photothermal agents. Both

in vitro

and

in vivo

studies confirmed that PBIQ NPs enable precise tumor diagnosis and efficient ablation with excellent biocompatibility. This work highlights the critical role of spatial steric hindrance in balancing radiative and nonradiative transitions

offering a promising molecular design paradigm for integrated NIR-II phototheranostics.

关键词

Keywords

references

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