Organic Fluorophores with Large Stokes Shift for Bioimaging and Biosensing

Abstract

Fluorophores and fluorophores‐based probes or labels can visualize the structures and content fluctuations of biomolecules, and have made great progress in the broad range of biomedicine fields. However, many commercially available fluorophores suffer from small Stokes shift, which results in insufficient signal‐to‐noise ratio and self‐quenching in advanced imaging techniques. Moreover, the small Stokes shift also hinders the application of fluorophores in some complex imaging, such as single‐excitation multicolor imaging. In the past two decades, many effects have been made to enlarge Stokes shift of fluorophores. In this review, we clarified the reasons for the small Stokes shift building on the structural analysis of fluorophores, systematically summarize the methods of structural modification to increase Stokes shift, and present some representative applications of fluorophores with large Stokes shift in imaging and sensing.

An Asymmetric NIR-II Organic Fluorophore with an Ultra-Large Stokes Shift for Imaging-Guided and Targeted Phototherapy

“…Due to the charge separation between the donor and the acceptor groups, the ICT state is highly polar and the excited state becomes significantly stabilized in polar solvents, causing the red shift of the emission . In addition, it seems that an asymmetric fluorophore exhibits larger degrees of asymmetric electron distribution of the HOMO and LUMO, thus exacerbating vibrational relaxation and resulting in a large Stokes shift. ,, Taken together, the asymmetric electronic structure and ICT features resulted in a large Stokes shift of TBy.…”

“…47 In addition, it seems that an asymmetric fluorophore exhibits larger degrees of asymmetric electron distribution of the HOMO and LUMO, thus exacerbating vibrational relaxation and resulting in a large Stokes shift. 30,44,48 Taken together, the asymmetric electronic structure and ICT features resulted in a large Stokes shift of TBy.…”

A Molecular Hybrid of the GFP Chromophore and 2,2′-Bipyridine: An Accessible Sensor for Zn2+ Detection with Fluorescence Microscopy

“…20 nm blue shifted, which makes excitation possible using the blue channel light sources of microscopes instead of the green needed for previous sensors. Combined with the 70 nm Stokes shift, this feature enables the filtration of scattered excitation light without significant losses in the collection of fluorescence photons [ 34 ]. Any light source under 420 nm, including the very popular 405 nm laser, enables the complete detection of emitted light, as the emission spectrum does not overlap with this region.…”