Spectroscopic Study of the Interaction of Styrylcyanine Dyes Sbo,Sil and Their Derivatives with Bovine Serum Albumin

The spectral-luminescent characteristics of newly synthesized styrylcyanine dyes on the base of dyes Sbo ((E)-2-(4-(dimethylamino)styryl)-3-methylbenzod]oxazol-3-ium iodide) and Sil ((E)-2-(4-(dimethylamino)styryl)-1,3,3-trimethyl-3H-indolium perchlorate) in aqueous solutions without and in the presence of bovine serum albumin (BSA) were studied. It was established that the absorption spectra of dyes Tol-6, Dbo-10 and Dil-10 with increasing amount of BSA appear new bands with λ_max = 505 nm, λ_max = 512 nm and λ_max = 566 nm, respectively, whose intensity increases in proportion to the amount of albumin. The intensity of the glow of the main band of fluorescence in the presence of BSA sharply increases. The binding constant (K) and the number of binding sites (N) of studied dyes with BSA were determined. The dependence of binding constants with BSA on the dipole moment of dye molecules was determined, which indicates that besides electrostatic forces of attraction between molecules styrylcyanine dyes with BSA, hydrophobic interactions are essential.