Amphiphilic Molecules Exhibiting Zwitterionic Excited-State Intramolecular Proton Transfer and Near-Infrared Emission for the Detection of Amyloid β Aggregates in Alzheimer's Disease**

Zhengxin Yu, Yusuff Moshood, Marcin K. Wozniak, Shrey Patel, Karna Terpstra, Daniel A. Llano, Lawrence W. Dobrucki, Liviu M. Mirica

Research output: Contribution to journalArticlepeer-review

Abstract

Chromophores with zwitterionic excited-state intramolecular proton transfer (ESIPT) have been shown to have larger Stock shifts and red-shifted emission wavelengths compared to the conventional π-delocalized ESIPT molecules. However, there is still a dearth of design strategies to expand the current library of zwitterionic ESIPT compounds. Herein, a novel zwitterionic excited-state intramolecular proton transfer system is reported, enabled by addition of 1,4,7-triazacyclononane (TACN) fragments on a dicyanomethylene-4H-pyran (DCM) scaffold. The solvent-dependent steady-state photophysical studies, pKa measurements, and computational analysis strongly support that the ESIPT process is more efficient with two TACN groups attached to the DCM scaffold and not affected by polar protic solvents. Impressively, compound DCM-OH-2-DT exhibits a near-infrared (NIR) emission at 740 nm along with an uncommonly large Stokes shift. Moreover, DCM-OH-2-DT shows high affinity towards soluble amyloid β (Aβ) oligomers in vitro and in 5xFAD mouse brain sections, and we have successfully applied DCM-OH-2-DT for the in vivo imaging of Aβ aggregates and demonstrated its potential use as an early diagnostic agent for AD. Overall, this study can provide a general molecular design strategy for developing new zwitterionic ESIPT compounds with NIR emission in vivo imaging applications.

Original languageEnglish (US)
Article numbere202302408
JournalChemistry - A European Journal
Volume29
Issue number64
DOIs
StatePublished - Nov 16 2023

Keywords

  • Alzheimer's disease
  • amyloid-β oligomers
  • early diagnosis
  • near-infrared fluorescence imaging
  • zwitterionic excited-state intramolecular proton transfer

ASJC Scopus subject areas

  • General Chemistry
  • Catalysis
  • Organic Chemistry

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