(722b) Interfacial Properties of a Glycocalyx-Mimetic Model

The glycocalyx is a polysaccharide coating covering the cell membrane of many types of cells. The glycocalyx is mainly constituted by molecules with a high fraction of polysaccharides, such as glycolipids, glycoproteins, proteoglycans and glycosaminoglycans. These polysaccharides are exposed on the surface of the plasma membrane, and their biochemical and biophysical properties influence the surface properties of cells and tissues, contributing to phenomena such as cell recognition, cell communication, cell adhesion and phagocytosis. Moreover, the glycocalyx has a relevant impact on processes such as drug delivery, infections, gene therapies, transplant rejection or pathologies such as diabetes, ischemia, atherosclerosis or cancer.

Although many specific surface events of cells (such as ligand-receptor interactions) have been studied extensively, non-specific interactions (such as interfacial tension) are important for phenomena such as initial adhesion, wettability and stability of aqueous films. These are important for a group of diseases involving the dryness of the mucosal tissues, such as xerostomia (dry mouth), or the dry eye syndrome.

The wetting properties of mucosal tissues, such as eye, mouth or trachea have traditionally been attributed to the presence of a hydrophilic glycocalyx, characteristic of healthy mucosal tissues. However, there is a lack of studies directly correlating the expression and spatial distribution of the glycocalyx on the mucosal tissues. By modulating the expression of glycocalyx molecules on cell cultures, we have found evidence that the stability of liquid films on biological surfaces is highly dependent on the heterogeneity of the surface. In this work we discuss the contribution of hydrophilic moieties on the surface of biomimetic substrates. Specifically we address the influence of different biomimetic substrates displaying hydrophilic molecules on their surface on their wettability and stability to fluid films.

Biomimetic surfaces were prepared on glass slides coated with films of poly-L-lysine (PLL)/Hyaluronic Acid (HA), and supported lipid bilayers functionalized with Poly(Ethylene Glycol) (PEG). The surfaces were characterized by measuring contact angle and contact angle hysteresis in a 2-fluid system. The contact angle did not change significantly with the functionalization of the surfaces. However, the contact angle hysteresis increase suggested a development of surface heterogeneity similar to that observed in cell culture experiments.