A wavelength-ratiometric pH sensitive probe based on the boronic acid moiety and suppressed sugar response.

We characterize a new water soluble fluorescent probe sensitive to changes in pH. The new probe shows spectral shifts and intensity changes in different pH media, in a wavelength ratiometric and colorimetric manner. Subsequently, changes in pH can readily be determined around the physiological level. The new probe's response is based on the ability of the boronic acid group to interact with strong bases like OH-, changing from the neutral form of the boronic acid group [R-B(OH)2] to the anionic R-B-(OH)3 form, which is an electron donating group. The presence of an electron deficient quaternary heterocyclic nitrogen center and a strong electron donating amino group in the 6-position, on the quinolinium backbone, provides for the spectral changes observed upon OH- complexation. In addition, the presence of the amino group in the 6-position of the quinolinium backbone, suppresses the response of the boronic acid containing probe towards mono saccharides such as glucose and fructose, which are present in many biological fluids, allowing for the predominant pH sensitivity. Finally we compare our findings to those of a control compound that does not contain the boronic acid group.

[1]  J. Lakowicz,et al.  Spectral Properties of Fluorophores Combining the Boronic Acid Group with Electron Donor or Withdrawing Groups. Implication in the Development of Fluorescence Probes for Saccharides. , 2001, The journal of physical chemistry. A.

[2]  N. Clement,et al.  Pyranine (8-hydroxy-1,3,6-pyrenetrisulfonate) as a probe of internal aqueous hydrogen ion concentration in phospholipid vesicles. , 1981, Biochemistry.

[3]  J. Lakowicz,et al.  Charge transfer fluorescent probes using boronic acids for monosaccharide signaling. , 2002, Journal of biomedical optics.

[4]  J. Lakowicz.  Principles of fluorescence spectroscopy , 1983 .

[5]  E. Racker,et al.  Intracellular pH measurements in Ehrlich ascites tumor cells utilizing spectroscopic probes generated in situ. , 1979, Biochemistry.

[6]  J. Lakowicz,et al.  Wavelength-ratiometric probes for saccharides based on donor-acceptor diphenylpolyenes. , 2001, Journal of photochemistry and photobiology. A, Chemistry.

[7]  J. Lakowicz,et al.  Fluorescence-sensing methods. , 2003, Methods in enzymology.

[8]  J. GRIFFITHS,et al.  Dyes and Pigments , 1971, Nature.

[9]  R. M. Threatte,et al.  Fluorescence of 6-methoxyquinoline, quinine, and quinidine in aqueous media. , 1974, Journal of pharmaceutical sciences.

[10]  David R. Walt,et al.  A fiber-optic sensor for CO2 measurement , 1988 .

[11]  Y. Kawabata,et al.  Fiber-optic sensor for carbon dioxide with a ph indicator dispersed in a poly(ethylene glycol) membrane , 1989 .

[12]  W. Rudolf Seitz,et al.  A fluorescence sensor for quantifying pH in the range from 6.5 to 8.5 , 1984 .

[13]  J. Lakowicz,et al.  New sensitive and selective fluorescent probes for fluoride using boronic acids. , 2002, Analytical biochemistry.

[14]  B Poole,et al.  Fluorescence probe measurement of the intralysosomal pH in living cells and the perturbation of pH by various agents. , 1978, Proceedings of the National Academy of Sciences of the United States of America.

[15]  D R Walt,et al.  A fiber-optic sensor for CO(2) measurement. , 1988, Talanta.

[16]  R. Haugland,et al.  Spectral and photophysical studies of benzo[c]xanthene dyes: dual emission pH sensors. , 1991, Analytical biochemistry.

[17]  Otto S. Wolfbeis,et al.  Dependence of the fluorescence of immobilized 1-hydroxypyrene-3,6,8-trisulfonate on solution pH: Extension of the range of applicability of a pH fluorosensor , 1995 .

[18]  J. Kao,et al.  Practical aspects of measuring [Ca2+] with fluorescent indicators. , 1994, Methods in cell biology.