Szmacinski H, Gryczynski I, Lakowicz J R
Department of Biological Chemistry, University of Maryland at Baltimore 21201.
Photochem Photobiol. 1993 Sep;58(3):341-5. doi: 10.1111/j.1751-1097.1993.tb09571.x.
We characterized the fluorescence intensity decays of Indo-1, which is commonly used as an emission wavelength-ratiometric calcium probe. The apparent lifetime of the long-wavelength side of the emission of Indo-1 is dependent on Ca2+. This long-wavelength emission displays the characteristics of an excited-state reaction, that is, a negative preexponential component in the multiexponential analysis. The emission spectra and lifetime of Indo-1 appear to be identical for one-photon and two-photon excitation at 351 and 702 mn, respectively, suggesting that the relative one- and two-photon cross sections are similar for the calcium-free and calcium-bound forms of Indo-1. Also, the two-photon cross section of Indo-1 is relatively high, about 4 x 10(-49) cm4 s/photon molecule at 690 nm for both the calcium-free and calcium-bound forms. Hence, Indo-1 can be used for calcium imaging based on one- or two-photon excitation, using either emission wavelength ratios or lifetime imaging methods.
我们对常用作发射波长比率型钙探针的Indo-1的荧光强度衰减进行了表征。Indo-1发射长波长侧的表观寿命取决于Ca2+。这种长波长发射表现出激发态反应的特征，即在多指数分析中存在负的前指数成分。Indo-1在351和702 mn处的单光子和双光子激发下的发射光谱和寿命似乎相同，这表明Indo-1的无钙和钙结合形式的相对单光子和双光子截面相似。此外，Indo-1的双光子截面相对较高，对于无钙和钙结合形式，在690 nm处约为4×10(-49) cm4 s/光子分子。因此，Indo-1可用于基于单光子或双光子激发的钙成像，可采用发射波长比率或寿命成像方法。
