Research Progress in 1,8-Naphthalimide-Based Fluorescent Probes for Two-Photon Imaging

Fluorescent imaging technology has received great attention owing to their advantageous features in high sensitivity, relatively simple operations and real-time living cells, tissue and in vivo imaging. Compared with one-photon confocal imaging, two-photon confocal imaging offers considerable advantages such as high resolution, deep-tissue depth, lower tissue auto-fluorescence and so on. As typical D-pi-A two-photon dyes, 1,8-naphthalimide dyes have wide application in two-photon imaging for enzyme, reactive carbon species, reactive oxygen species, reactive nitrogen species, biothiols and ions due to their advantages such as high photostability, large Stokes/anti-Stokes shifts. According to the mechanisms of intramolecular charge transfer, photoinduced electron transfer and fluorescence resonance energy transfer, etc., the application in two-photon imaging of 1,8-naphthalimide dyes is summarized and emphasized.