[Fluorescence reaction of the system of safranine T-sodium dodecylbenzene sulfonate-protein and its application].

There is a self-polymerization equilibrium system between the cation of the fluorescent dye-safranine T and its dimer. In the presence of appropriate amounts of anionic surfactant SDBS, the above mentioned equilibrium can be adjusted by a quantitative addition of protein, thus leading to a regular change in the fluorescence intensity of the system. Based on this phenomenon, the properties of the absorption spectrum and fluorescence spectrum of the system were studied, and a new fluorescence probe for the determination of protein was established. It was found that ST was apt to dimerize in the solution added with appropriate amounts of anionic surfactant. Because of the dimerization, its fluorescence intensity decreased, whereas the addition of protein caused the dimer to be depolymerized and the system fluorescence increased. A linear relationship between the fluorescence intensities and serum albumin concentration was found in the range of 0-40 microg x mL(-1) , and the detection limit found was 0.034 microg x mL(-1). The significant features of this method were its rapidity of reaction, and high sensitivity, accuracy and selectivity. The method was applied to the determination of total proteins in real human serum, and satisfactory results were obtained.