Microcalorimetric and zeta potential study on binding of drugs on liposomes

In this work, isothermal titration calorimetry (ITC) combined with zeta potential measurements was used to study the binding and partitioning of three β-blockers, alprenolol, labetalol and propranolol, and the local anaesthetic tetracaine into liposomes. The thermodynamic parameters of enthalpy, entropy, the Gibbs energy and the binding constant were determined using the one site model. Furthermore, the binding constants corrected for the electrostatic contribution were used to assess the partition coefficients for the drugs. Also, the effect of the concentration, ionic strength, temperature and membrane curvature on the interaction was included in the evaluation.