The spectral-luminescent characteristics of cyanine dye Cyan 40 and thiazole orange at interaction with
biomacromolecules bovine serum albumin and deoxyribonucleic acid was studied. It is shown that presence
of biomacromolecules in solution of the studied species leads to the change of spectral-luminescent
characteristics of the dyes Cyan 40 and TO. The observed phenomena in absorption spectrum and
fluorescence of the studied dyes is explained by complex formation between dye and biological
macromolecules. The binding parameters: a binding constant (K) and quantity of the binding sites (N) the
studied dyes with biomacromolecules are determined.