Human Immunoglobulin Adsorption Investigated by Means of Quartz Crystal Microbalance Dissipation,Atomic Force Microscopy,Surface Acoustic Wave,and Surface Plasmon Resonance Techniques

摘要

Time-resolved adsorption behavior of a human immunoglobin G (hlgG) protein on a hydrophobized gold surface is investigated using multitechniques: quartz crystal microbalance/dissipation (QCM-D) technique;combined surface plasmon resonance (SPR) and Love mode surface acoustic wave (SAW) technique;combined QCM-D and atomic force microscopy (AFM) technique.The adsorbed hIgG forms interfacial structures varying in organization from a submonolayer to a multilayer.An "end-on" IgG orientation in the monolayer film,associated with the surface coverage results,does not corroborate with the effective protein thickness determined from SPR/SAW measurements.This inconsistence is interpreted by a deformation effect induced by conformation change.This conformation change is confirmed by QCM-D measurement.Combined SPR/SAW measurements suggest that the adsorbed protein barely contains water after extended contact with the hydrophobic surface.This limited interfacial hydration also contributed to a continuous conformation change in the adsorbed protein layer.The viscoelastic variation associated with interfacial conformation changes induces about 1.5 times overestimation of the mass uptake in the QCM-D measurements.The merit of combined multitechnique measurements is demonstrated.