The inside surfaces of healthy blood vessels are lined with endothelial cells that present a polysaccharide-rich layer forming the interface between the flowing blood and blood vessel wall. This vascular endothelial glycocalyx performs several important dynamic physiological functions that make the inside surfaces of healthy blood vessels the most blood-compatible surface known. In fact, all other synthetic or biological materials that contact blood can induce inflammation, blood clotting, and infection. The structure and composition of this glycocalyx inspires us to investigate how the presentation of similar polysaccharide chemistries on surfaces should be tuned to improve blood-material interactions.<br/>The polysaccharides in the vascular endothelial glycocalyx include important glycosaminoglycans – polyanionic macromolecules – presented in a brush-like layer as the side chains on proteoglycans. The formation of dense polyelectrolyte brushes with thicknesses approaching the thickness of this unique biological structure (100s of nm to a few microns) is energetically unfavorable, due to both enthalpic (electrostatic repulsion) and entropic (chain stretching) barriers. Nonetheless, we hypothesize that this thick, brush-like presentation of glycosaminoglycans may enable favorable blood-surface interactions, such as blood protein stabilization, protein-surface interactions, and protein-protein interactions.<br/>We have developed brush-like glycosaminoglycan (polyanion) coatings with dimensions approaching the dimensions of the endothelial glycocalyx. The composition and structure of these coatings can be controlled over a range of parameter space that enables us to determine structure-property relationships. We characterize their surface chemistry by vibrational and X-ray spectroscopy, and confocal fluorescence spectroscopy. We characterize their structure and nanomechanical properties by atomic force microscopy using peak force quantitative nanomechanical property mapping (PF-QNM), in liquid. We are using these to further elucidate structure-property-function relationships by single-particle protein diffusion experiments in these polymer brushes, to discern how key blood proteins interact differently within these polymer brushes than on flat surfaces.<br/>This work will provide a new model system upon which to test hypotheses about blood-material interactions, and a strategy for designing blood-contacting materials with improved blood compatibility.

Glycosaminoglycan nanostructures as mimics of the vascular endothelial glycocalyx

253rd National Meeting (2017)

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