A ratiometric two-photon probe for Cain live tissues and its application to spinal cord injury model.

Abstract

Ratiometric imaging with a small-molecule probe is important for the in-situ quantitative analysis of chemical events. We developed a ratiometric two-photon fluorescent probe (SCa1-I) derived from dual dyes with different Stokes shifts. This probe has two identical windows: a Ca-sensing window and an internal reference window, with eliminated FRET interference. SCa1-Ishows a marked change in the ratio upon response with Ca, significant two-photon brightness, considerable selectivity for Ca, and cell loading ability with low cytotoxicity. The ratiometric two-photon microscopy images revealed that this probe could directly and quantitatively estimate Cain live neurons and various tissues including rat spinal cord tissue. The studies of spinal cord injury model revealed that the Calevel was significantly affected by elapsed time after injury. These results will provide useful applications for in-situ [Ca]imaging and for the development of effective ratiometric probes.