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Photophysics of a xanthenic derivative dye useful as an "on/off" fluorescence probe

Photophysics of a xanthenic derivative dye useful as an "on/off" fluorescence probe
Photophysics of a xanthenic derivative dye useful as an "on/off" fluorescence probe
The photophysical behavior of a new fluorescein derivative 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 both the absorbance and fluorescence has been investigated. The apparent acidity constant of the dye determined by absorbance is almost independent of the added buffer and salt concentrations. A semiempirical model is proposed to rationalize the variations in the apparent pKa values. The excited-state proton-exchange reaction around the physiological pH becomes reversible upon addition of phosphate buffer, inducing a pH-dependent change of the steady-state fluorescence and 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: k01 = 1.29 x 10(10) s(-1), k02 = 4.21 x 10(8) s(-1), k21 approximately 3 x 10(6) M(-1) s(-1), k12B= 6.40 x 10(8) M(-1) s(-1), and k21B = 2.61 x 10(7) M(-1) s(-1). The decay rate constant values of k01, k21, k21B, along with the low molar absorption coefficient of the neutral form, mean that coupled decays are practically monoexponential at buffer concentrations higher than 0.02 M and any pH. Thus, the pH and buffer concentration can modulate the main lifetime of the dye.
1089-5639
13311-13320
Crovetto, Luis
45d4cd97-3fe5-4498-a861-bc06492eb09d
Paredes, Jose M.
56f39307-ce21-4a3c-9ec5-61dfc850ab43
Rios, Ramon
609bedf2-e886-4d62-a676-a32b6f8c1441
Talavera, Eva M.
e0319787-e90f-48dd-b89f-5c631bbe15a1
Alvarez-Pez, Jose M.
6970f24c-ecb5-418b-9847-f7a6be1d91f2
Crovetto, Luis
45d4cd97-3fe5-4498-a861-bc06492eb09d
Paredes, Jose M.
56f39307-ce21-4a3c-9ec5-61dfc850ab43
Rios, Ramon
609bedf2-e886-4d62-a676-a32b6f8c1441
Talavera, Eva M.
e0319787-e90f-48dd-b89f-5c631bbe15a1
Alvarez-Pez, Jose M.
6970f24c-ecb5-418b-9847-f7a6be1d91f2

Crovetto, Luis, Paredes, Jose M., Rios, Ramon, Talavera, Eva M. and Alvarez-Pez, Jose M. (2007) Photophysics of a xanthenic derivative dye useful as an "on/off" fluorescence probe. Journal of Physical Chemistry A, 111 (51), 13311-13320. (doi:10.1021/jp077249o). (PMID:18092761)

Record type: Article

Abstract

The photophysical behavior of a new fluorescein derivative 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 both the absorbance and fluorescence has been investigated. The apparent acidity constant of the dye determined by absorbance is almost independent of the added buffer and salt concentrations. A semiempirical model is proposed to rationalize the variations in the apparent pKa values. The excited-state proton-exchange reaction around the physiological pH becomes reversible upon addition of phosphate buffer, inducing a pH-dependent change of the steady-state fluorescence and 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: k01 = 1.29 x 10(10) s(-1), k02 = 4.21 x 10(8) s(-1), k21 approximately 3 x 10(6) M(-1) s(-1), k12B= 6.40 x 10(8) M(-1) s(-1), and k21B = 2.61 x 10(7) M(-1) s(-1). The decay rate constant values of k01, k21, k21B, along with the low molar absorption coefficient of the neutral form, mean that coupled decays are practically monoexponential at buffer concentrations higher than 0.02 M and any pH. Thus, the pH and buffer concentration can modulate the main lifetime of the dye.

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Published date: 20 December 2007
Organisations: Chemistry

Identifiers

Local EPrints ID: 347991
URI: https://eprints.soton.ac.uk/id/eprint/347991
ISSN: 1089-5639
PURE UUID: e04a38bd-39d8-4fc4-ba45-d3bd3651fac2
ORCID for Ramon Rios: ORCID iD orcid.org/0000-0002-3843-8521

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Date deposited: 05 Feb 2013 10:52
Last modified: 20 Jul 2019 00:42

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Contributors

Author: Luis Crovetto
Author: Jose M. Paredes
Author: Ramon Rios ORCID iD
Author: Eva M. Talavera
Author: Jose M. Alvarez-Pez

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