Abstract:
Deep tissue bioimaging with three-photon (3P)
excitation using near-infrared (NIR) light in the second IR
window (1.0–1.4 mm) could provide high resolution
images with an improved signal-to-noise ratio. Herein, we
report a photostable and nontoxic 3P excitable donor-pacceptor
system (GMP) having 3P cross-section (s3) of
1.78Õ10¢80 cm6 s2photon¢2 and action cross-section (s3h3)
of 2.31Õ10¢81 cm6 s2photon¢2, which provides ratiometric
fluorescence response with divalent zinc ions in aqueous
conditions. The probe signals the Zn2+ binding at 530 and
600 nm, respectively, upon 1150 nm excitation with enhanced
s3 of 1.85Õ10¢80 cm6 s2photon¢2 and s3h3 of
3.33Õ10¢81 cm6 s2photon¢2. The application of this probe
is demonstrated for ratiometric 3P imaging of Zn2+ in
vitro using HuH-7 cell lines. Furthermore, the Zn2+ concentration
in rat hippocampal slices was imaged at
1150 nm excitation after incubation with GMP, illustrating
its potential as a 3P ratiometric probe for deep tissue
Zn2+ ion imaging
