Calcium sensitive fluorophore

Figure 6.4 Fluor-3 penla-acyloxymethyl ester passively diffuses into cells where it is cleaved by esterases and trapped as the parent compound, a calcium-sensitive fluorophore.

Fig. 8.2. Examples of ion exchange, monitored by FCS. (a) FITC measured at different pH. Decays of the correlation curves in the 1ms, 2-80 xs, and l xs time range are attributed to translational diffusion, proton exchange and single-triplet state transitions of the fluorophores, respectively, (b) FITC at pH6, with different concentrations of phosphate buffer. Inset Measured fcprot vs. concentration of buffer/salt at pH6. (c) FCS curves of GFP (S65T) at different pH. (d) The calcium sensitive dye Rh-II, measured at different concentrations of free calcium...

M-5 (Quin-2) was the first practical fluorescent indicator for cytosolic calcium with a simple 6-methoxyquinoline as its fluorophore. Ca2+-binding increases the fluorescence intensity about six-fold (without spectral displacement, in contrast to Fura 2 see Section 10.3.3). The fluorescence lifetime of Quin-2 is highly sensitive to calcium concentration Quin-2 can thus be used as a probe in the technique of fluorescence lifetime imaging. 

Fig. 4. A molecular OR gate in the shape of compound 3. With both proton and calcium ion sensitivity, the tertiary amine atom will quench fluorescence of the fluorophore a in the absence of both stimuli. The presence of one b or c the other stimulus reduces the ability of the nitrogen lone pair to participate in PET. The same is true when d both stimuli are added to the solution...

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