Thermodynamic Analysis of the Interaction between Cationic Porphyrins and Human Serum Albumin by an Optical Biosensor

Abstract

An optical biosensor with a stirred cuvette has been used to monitor the interaction between immobilized human serum albumin (HSA) and three water-soluble cationic porphyrins. The binding constants at 25 ℃ obtained from biosensor analysis were compared with those from fluorescence spectroscopy. The interactions were further investigated at temperatures from 15 ℃ to 30 ℃. The thermodynamics parameters, changes of free energy (∆G), enthalpy (∆H) and entropy (∆S), were evaluated from equilibrium data. It appeared that the binding process was governed primarily by electrostatic forces.