Naslov
Photophysics of the Fluorescent pH Indicator BCECF

Autori
Boens, Noël ; Qin, Wenwu ; Basarić, Nikola ; Orte, Angel ; Talavera, Eva M. ; Alvarez-Pez, Jose M.

Izvornik
The Journal of Physical Chemistry A (1089-5639) 110 (2006), 30; 9334-9343

Vrsta, podvrsta i kategorija rada
Radovi u časopisima, članak, znanstveni

Ključne riječi
absorption; BCECF; fluorescence; global analysis; photophysics; pH

Sažetak
The photophysical behavior of BCECF [2', 7'-bis-(2-carboxyethyl)-5-(and-6)-carboxyfluorescein] − currently the most widely used fluorescent pH indicator for near-neutral intracellular pH measurements – has been explored by using absorption and steady-state and time-resolved fluorescence measurements. The influence of ionic strength as well as total buffer concentration on the absorbance and steady-state fluorescence has been investigated. The apparent acidity constant of the pH indicator determined by absorbance and fluorescence titration is dependent on the added buffer and salt concentrations. A semi-empirical model is proposed to rationalize the variations in the apparent pKa values. The excited-state proton exchange of BCECF at physiological pH becomes reversible upon addition of phosphate buffer inducing a pH dependent change of the fluorescence decay times. Fluorescence decay traces collected as a function of total buffer concentration and pH were analyzed by global compartmental analysis yielding the following values of the rate constants describing excited-state dynamics of BCECF: k01 = 3.4 x 108 s− 1, k02 = 2.6 x 108 s− 1, k21 = 1 x 106 M− 1 s− 1, = 1.4 x 108 M− 1 s− 1, and = 4.3 x 107 M− 1 s− 1.

Izvorni jezik
Engleski

Znanstvena područja
Kemija

POVEZANOST RADA