Planar and Twisted Molecular Structure Leads to the High Brightness of Semiconducting Polymer Nanoparticles for NIR-IIa Fluorescence Imaging

Shunjie Liu; Hanlin Ou; Yuanyuan Li; Haoke Zhang; Junkai Liu; Xuefeng Lu; Ryan T K Kwok; Jacky W Y Lam; Dan Ding; Ben Zhong Tang

doi:10.1021/jacs.0c07193

Planar and Twisted Molecular Structure Leads to the High Brightness of Semiconducting Polymer Nanoparticles for NIR-IIa Fluorescence Imaging

J Am Chem Soc. 2020 Sep 2;142(35):15146-15156. doi: 10.1021/jacs.0c07193. Epub 2020 Aug 19.

Authors

Shunjie Liu¹, Hanlin Ou², Yuanyuan Li¹, Haoke Zhang¹, Junkai Liu¹, Xuefeng Lu¹, Ryan T K Kwok¹, Jacky W Y Lam¹, Dan Ding², Ben Zhong Tang^{1

3

4}

Affiliations

¹ Department of Chemistry, Hong Kong Branch of Chinese National Engineering Research Center for Tissue Restoration and Reconstruction, Division of Life Science and State Key Laboratory of Molecular Neuroscience, and Division of Biomedical Engineering, The Hong Kong University of Science and Technology, Clear Water Bay, Kowloon 999077, Hong Kong, China.
² State Key Laboratory of Medicinal Chemical Biology, Key Laboratory of Bioactive Materials, Ministry of Education, and College of Life Sciences, Nankai University, Tianjin 300071, China.
³ HKUST-Shenzhen Research Institute, No. 9 Yuexing first RD, South Area, Hi-tech Park, Nanshan, Shenzhen 518057, China.
⁴ Center for Aggregation-Induced Emission, SCUT-HKUST Joint Research Institute, State Key Laboratory of Luminescent Materials and Devices, South China University of Technology, Guangzhou 510640, China.

PMID: 32786775
DOI: 10.1021/jacs.0c07193

Abstract

Semiconducting polymer nanoparticles (SPNs) emitting in the second near-infrared window (NIR-II, 1000-1700 nm) are promising materials for deep-tissue optical imaging in mammals, but the brightness is far from satisfactory. Herein, we developed a molecular design strategy to boost the brightness of NIR-II SPNs: structure planarization and twisting. By integration of the strong absorption coefficient inherited from planar π-conjugated units and high solid-state quantum yield (Φ_PL) from twisted motifs into one polymer, a rise in brightness was obtained. The resulting pNIR-4 with both twisted and planar structure displayed improved Φ_PL and absorption when compared to the planar polymer pNIR-1 and the twisted polymer pNIR-2. Given the emission tail extending into the NIR-IIa region (1300-1400 nm) of the pNIR-4 nanoparticles, NIR-IIa fluorescence imaging of blood vessels with enhanced clarity was observed. Moreover, a pH-responsive poly(β-amino ester) made pNIR-4 specifically accumulate at tumor sites, allowing NIR-IIa fluorescence image-guided cancer precision resection. This study provides a molecular design strategy for developing highly bright fluorophores.

Publication types

Research Support, Non-U.S. Gov't