Albumins are the most abundant proteins in body fluids and transport small molecules throughout the body. Because serum albumin levels are prognostic indicators of liver disease and other pathological conditions, the development of analytical methods for albumin analysis and the study of their interactions with small molecules are highly relevant.
We investigated a broad series of indolenine, benzoxazole, benzothiazole and benzoselenazole squaraine dyes as fluorescent probes for protein determination, including albumins, insulin, lysozyme and immunoglobulin G. Benzothiazole squaraines bearing long N-alkyl substituents were shown to be highly selective for albumins, increasing their fluorescence intensity approximately 400-fold in the presence of this protein class. Some of these dyes enable quantitative determination of human serum albumin over a range from 0.2 mg/mL to 500 mg/mL, with sensitivity comparable to that of the commercially available CBB and Pyrogallol Red Protein dyes.
In our view, owing to their high specificity for albumins, benzothiazole squaraines may be used to study the pharmacokinetics and pharmacodynamics of potential drug candidates. The affinity of a dye for site I or site II of human serum albumin was shown to be determined by the nature of the substituent in its squarylium ring.
Publications
- K. D. Volkova, V. B. Kovalska, M. Yu. Losytskyy, L. V. Reis, P. F. Santos, P. Almeida, D. E. Lynch, S. M. Yarmoluk. Aza-substituted squaraines for the fluorescent detection of albumins. Dyes and Pigments. 2011;90:41–47.
- K. D. Volkova, V. B. Kovalska, M. Yu. Losytskyy, A. Bento, L. V. Reis, P. F. Santos, P. Almeida, S. M. Yarmoluk. Studies of Benzothiazole and Benzoselenazole Squaraines as Fluorescent Probes for Albumins Detection. Journal of Fluorescence. 2008;18(5):877–882.
- K. D. Volkova, V. B. Kovalska, A. L. Tatarets, L. D. Patsenker, D. V. Kryvorotenko, S. M. Yarmoluk. Spectroscopic study of squaraines as protein-sensitive fluorescent dyes. Dyes and Pigments. 2007;72(3):285–292.