Organic fluorophores with large Stokes shift for bioimaging and biosensing

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. The review has systematically summarized several methods recently developed to increase Stokes shift of fluorophores by structural modification, and highlighted typical applications of fluorophores with large Stokes shift in single-excitation multi-color imaging and ratiometric imaging. The review will provide a theoretical guidance for the design of novel fluorophores with large Stokes shift.image