Progress and application of two-photon fluorescent probes

Two-photon fluorescence imaging with such properties as NIR ( near infrared) photons as excitation source, imaging in the black background, avoidance of photodamage and photobleaching, fixed target excitation, high transverse and longitudinal resolutions, small absorption coefficient of light in tissue, lower tissue auto-fluorescence, etc. is superior to one-photon fluorescence imaging, and is a powerful tool for life science studies. Two-photon fluorescence probes applied to studies on the contents of ions and the effects of their contents upon physiology, physiological action mechanisms of ions, interplays between ions and molecules, distributions of specific molecules and their interactions, and so on, play an important role in imaging. The aim of the studies on two-photon fluorescence probes is to promote the developments of the applications for two-photon fluorescence microscopies, life science and medicine, and chemistry to which two-photon fluorescence probes are subject. Undoubtedly, the developments and applications of two-photon fluorescence probes are significantly meaningful in theory and practice. The advantages of two-photon fluorescence imaging, the principles of design for two-photon fluorescent probes and their applications in ions analyses are reviewed. In particular, the prospects in the future are also discussed.