Two‐Photon Fluorescent Probes for Long‐Term Imaging of Calcium Waves in Live Tissue

Abstract

2-Acetyl-6-(dimethylamino)naphthalene-derived two-photon fluorescent Ca2+ probes (ACa1-ACa3) are reported. They can be excited by a 780 nm laser beam, show 23-50-fold enhancement in one- and two-photon excited fluorescence in response to Ca2+, emit fourfold stronger two-photon excited fluorescence than Oregon Green 488 BAPTA-1 upon complexation with Ca2+, and can selectively detect intracellular free Ca2+ ions in live cells and living tissues with minimum interference from other metal ions and membrane-bound probes. Moreover, these probes are capable of monitoring calcium waves at a depth of 120-170 microm in live tissues for 1100-4000 s using two-photon microscopy with no artifacts of photobleaching.

Confocal and Multiphoton Imaging of Intracellular Ca2+

“…There is no guarantee that 2P excitation will successfully excite the dye since the efficiency of two photon excitation appears to be relative to the fluorophore structure (Kim et al 2008). A number of Ca-sensitive indicators have been studied over a limited range of 2P…”

“…In doing so, these studies are using the higher powers available from lasers at these wavelengths, rather than attempting to access the higher quantum yields that may be present at longer wavelengths. Further work is required to examine the optimal 2P conditions required to excite these readily available dyes at 1000-1100 nm, 21 or alternatively design new dyes with fluorophore structures that are more easily excited by the 2P approach (Kim et al 2008). .…”

A New Fluorescent Probe for Selective Detection of Endogenous Cysteine and Live Cell Imaging

“…The starting materials 1‐(6‐aminonaphthalen‐2‐yl) ethen‐1‐one was synthesized according to literature with small modifications (SI), where 2 eq. of Na 2 S 2 O 5 and shorter reaction time of 72 h were used here . MANK was obtained by the addition reaction through the aromatic amino group and the maleic anhydride, followed by the blocking of the terminal carboxyl group.…”

Photophysical properties of rhodamine isomers: A two-photon excited fluorescent sensor for trivalent chromium cation (Cr3+)

“…Second, two-photon excited fluorescence (TPEF) has low background, because of the large spectral separation of excitation light and fluorescence emission signal. Although the advantages of two-photon fluorescent sensors are clear, only a few metal ion sensors have been reported, and most of them are for bivalent ions [37][38][39][40][41][42][43][44][45][46][47][48][49][50][51][52][53][54][55]. The two-photon fluorescent sensors for trivalent ions are very rare.…”