Data for: Bioinspired Lubricity from Surface Gel Layers

Surface gel layers on commercially-available contact lenses have been shown to reduce frictional shear stresses and mitigate damage during sliding contact with fragile epithelial cell layers in vitro. Spencer and coworkers recently demonstrated that surface gel layers could arise by polymerizing hydrogels within molds composed of low surface energy materials and near oxygen-rich interfaces from peroxidation gradients. In this study, polyacrylamide hydrogel shell probes (7.5 wt.% polyacrylamide, 0.3 wt.% methylenebisacrylamide) were polymerized in three hemispherical molds listed in order of decreasing surface energy and increasing oxygen permeability: borosilicate glass, polyetheretherketone (PEEK), and polytetrafluoroethylene (PTFE). Hydrogel probes polymerized in PEEK and PTFE molds exhibited 100´ lower elastic moduli at the surface (E*PEEK = 80 ± 31 Pa and E*PTFE = 106 ± 26 Pa, respectively) than those polymerized in glass molds (E*glass = 31,560 ± 1,570 Pa), in agreement with previous investigations by Spencer and coworkers. Biotribological experiments revealed that hydrogel probes with surface gel layers reduced frictional shear stresses against cells (τPEEK = 35 ± 15 Pa and τPTFE = 22 ± 16 Pa) more than those without (τglass = 68 ± 15 Pa) and offered greater protection against cell damage when sliding against human telomerase-immortalized corneal epithelial (hTCEpi) cell monolayers. Our work demonstrates that the “mold effect” resulting in oxygen-inhibition polymerization creates hydrogels with surface gel layers that reduce shear stresses in sliding contact with cell monolayers, similar to the protection offered by gradient mucin gel networks across epithelial cell layers.