Abstract: The interaction of Cyclen-Co(Ⅱ) with bovine serum albumin(BSA) was investigated by fluorescence method. The results show that the Cyclen-Co(Ⅱ) strongly quenches the fluorescence of BSA. It has been proved that the fluorescence quenching mechanism belongs to the static quenching by Stern-Volmer equation and Lineweaver-Burk equation. According to Lineweaver-Burk equation and thermodynamics equation, the binding constants, binding sites and thermodynamics parameters were obtained at different temperatures in the aqueous solution and in the solutions of Brij35, CTAB, SDS surfactants. The Van der Waals′ forces play a main role in the binding of Cyclen-Co(Ⅱ) with BSA.

Key words: tetraazacyclododecane-Co(Ⅱ), Bovine serum albumin, fluorescence spectroscopy, Binding numbers, binding equilibrium constant