Surface Chemistry Induced IgG Unfolding and Modulation of Immune Responses

Immunoglobulin G (IgG) comprises a significant portion of the protein corona that forms on biomaterial surfaces and holds a pivotal role in modulating host immune responses. To shed light on the important relationship between biomaterial surface functionality, IgG adsorption, and innate immune responses, we prepared, using plasma deposition, four surface coatings with specific chemistries, wettability, and charge. We found that nitrogen-containing coatings such as these deposited from allylamine (AM) and 2-methyl-2-oxazoline (POX) cause the greatest IgG unfolding, while hydrophilic acrylic acid (AC) surfaces allowed for the retention of the protein structure. Structural changes in IgG significantly modulated macrophage attachment, migration, polarization, and the expression of pro- and anti-inflammatory cytokines. Unfolded IgG on the POX and AM surfaces enhanced macrophage attachment, migration, extracellular trap release, and pro-inflammatory factors production such as IL-6 and TNF-α. Retention of IgG structure on the AC surface downregulated inflammatory responses. The findings of this study demonstrate that the retention of protein structure is an essential factor that must be taken into consideration when designing biomaterial surfaces. Our study indicates that using hydrophilic surface coatings could be a promising strategy for designing immune-modulatory biomaterials for clinical applications.