Fig. 1. (a) The design strategy used for NIR-emitting amino-Si-pyronin (NIR-ASiP) dyes as well as a ratiometric sensing platform. EWG = electron-withdrawing group. (b and c) Normalized absorption (solid line) and emission (dash line) spectra of SiR (b) and ASiPj1 (c) in PBS (pH 7.4) containing 1% DMSO. (d) Emission spectral shift of ASiP dyes to NIR-ASiP dyes in PBS (pH 7.4) containing 1% DMSO. The emission spectra were obtained by excitation at the maximum absorbance wavelength of each dye.
