Thermodynamic analysis of r-hGH-polymer surface Interaction using isothermal titration calorimetry.Delivery of protein drugs would be an effective approach if mechanistic understanding of protein adsorption at solid/liquid surface is obtained and nonspecific adsorption can be controlled.  This study involves evaluation of the thermodynamic parameters for interaction between recombinant human growth hormone (r-hGH) and nanoparticles of poly (lactic- co- glycolic) acid polymer of different molecular weight.  Energy changes related to protein-nanoparticle interactions are usually very small and isothermal titration calorimetry (ITC) is the only technique that determines the binding constant (Ka), enthalpy, (ΔH) and stoichiometry, (n) in a single experiment.  Endothermic, entropically driven reaction was observed upon interaction of r-hGH with PLGA 5050 5E nanoparticles at pH 7.2, PLGA 5050 1A nanoparticles at pH 5.3 and pH 4.0.  ITC proved to be very efficient method in studying the thermodynamics of the protein polymer interaction. 
THERM