Bright Near-Infrared π-Conjugated Oligomer Nanoparticles for Deep-Brain Three-Photon Microscopy Excited at the 1700 nm Window in Vivo

Shengliang Li*, Xiangquan Deng, Hui Cheng, Xiaozhen Li, Yingpeng Wan, Chen Cao, Jie Yu, Ying Liu, Yi Yuan, Ke Wang*, Chun-Sing Lee*

*Corresponding author for this work

Research output: Journal Publications and ReviewsRGC 21 - Publication in refereed journalpeer-review

31 Citations (Scopus)

Abstract

The development of three-photon fluorophores with 1700 nm excitation is pressingly desirable for in vivo imaging of tissue resided deep inside the brain. Herein, we report a designed and synthesized fluorescent molecule (OFET) for in vivo mouse brain imaging with three-photon microscopy at a record imaging depth. The OFET molecule has a relatively high fluorescence brightness and has a near-infrared (NIR) maximum emission at 820 nm after integrating as water-dispersible nanoparticles (OEFT NPs). Under 1720 nm excitation, OFET NPs show a large three-photon action cross-section of 1.06 × 10-82 cms2/photon2, which is more than twice that of the commonly used sulforhodamine 101 (SR101) dye. Benefiting from the high tissue penetration depths for both the long excitation in the second NIR window of 1720 nm and the emission wavelength in the first NIR window of 820 nm, a high brightness, and a large action cross-section of three-photon, OFET NPs have good deep-brain imaging performance. Brain vasculatures of a mouse located at a depth of 1696 μm can be clearly resolved in vivo. With no observable cytotoxicity even in a high concentration, the present OFET NPs suggest that fluorescent π-conjugated oligomers are of great potential in high-resolution 3PM imaging of in vivo deep-tissue.
Original languageEnglish
Pages (from-to)12480-12487
JournalACS Nano
Volume16
Issue number8
Online published15 Aug 2022
DOIs
Publication statusPublished - 23 Aug 2022

Funding

K.W. acknowledges the support by the National Natural Science Foundation of China (No. 61975126 and 61775143); Science, Technology and Innovation Commission of Shenzhen Municipality (No. JCYJ20190808174 819083); and (Key) Project of Department of Education of Guangdong Province (No. 2017KZD XM073). C.-S.L. acknowledges the support by the University Grants Committee/Research Grants Council of the Hong Kong Special Administrative Region, China (No. JLFS/P-101/18). S.L. acknowledges the financial support by the National Natural Science Foundation of China (No. 52173135) and the Priority Academic Program Development (PAPD) of Jiangsu Higher Education Institutions.

Research Keywords

  • conjugated oligomer
  • near-infrared
  • three-photon microscopy
  • brain imaging
  • 1700 nm window
  • POLYMER DOTS
  • FLUORESCENCE

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