Differential scanning calorimetry (DSC) and isothermal calorimetric batch technique were used to monitor the heat-induced structural changes and adsorption properties of human immunoglobulin G (IgG), in native and hydrophobized states. The transition temperature (T max) and enthalpy of heat-induced conformational changes (Δcal H) of IgG in solution as well as the enthalpy change accompanying the adsorption of IgG onto hydrophilic silica (Δads H), were shown to depend on the degree of the protein hydrophobicity (number of covalently attached alkyl chains). The adsorption enthalpy for all forms of IgG at all surface concentrations was found to be endothermic, that is the process is entropy driven. Factors affecting the IgG adsorption onto silica are discussed.
