Study of hydrophobic interaction based binding of immunoglobulin G on synthetic membranes

Hydrophobic interaction based binding of immunoglobulin G (IgG) on synthetic membranes is relevant to areas such as bioseparations, immunoassays and biomaterials. Previous studies which focused on IgG binding on very hydrophobic surfaces are not unanimous on the orientation of the bound IgG molecule. In this paper we examine the mechanism of IgG binding on environment-responsive membranes possessing tunable hydrophobicity. Binding experiments were carried out in the membrane chromatography mode to avoid limitations associated with diffusional mass transport. Membrane-bound IgG was found to be capable of simultaneously binding both its antigen and Protein-A showing that the C-terminal region of Fc and the N-terminal region of Fab did not play any major role in membrane binding. This was confirmed by confocal laser scanning microscopy using fluorescent labeled proteins. The IgG molecule presumably interacted with the membrane surface primarily through its middle region consisting of the hinge and portion of upper Fc.