Surface chemistry mediated albumin adsorption, conformational changes and influence on innate immune responses

Abstract

The surface chemistry of biomaterials plays a pivotal role in regulating the type, amount, and conformational changes of adsorbed proteins, which then modulates the subsequent innate immune responses. Albumin is the most abundant protein in serum and a major constituent of the protein corona that forms on biomaterial surfaces. Therefore, it is important to understand the role of surface chemistry in albumin adsorption, surface induced conformational changes, and how this affects the subsequent immune responses. To interrogate these events, we generated model substrata with four tailored surface chemistries rich in amines, oxazolines, carboxylic acid groups and pure hydrocarbons via plasma polymerization. The positively charged amine and oxazoline rich surface chemistries caused greatest albumin adsorption and protein conformational changes. Our data demonstrated that macrophages (differentiated THP-1 cells) were able to interact with unfolded albumin via their scavenger receptors. The innate inflammatory responses were studied by measuring the expression of pro- and anti- inflammatory markers. As an overall trend, the pre-adsorption of albumin resulted in a reduction in the level of expression of pro-inflammatory cytokines while the secretion of anti-inflammatory markers was stimulated. This study provides valuable information, which could aid in the design of future biomaterials that elicit predictable immune response.