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.