Hydrogel Dynamics at charged surfaces as a function of salt concentration and surface ionization.

The understanding of gel dynamics at surfaces in various environments is essential for applications like underwater adhesion, medical sutures, contact lenses, etc. The dynamics of hydrogels at bulk has been explored with various light scattering technique, but little is known about the local network equilibrium and dynamics change at strongly interactive surfaces. Here, we use Differential Dynamic Microscopy (DDM) paired with confocal fluorescence imaging to study the network flactuation of negatively charged sodium hyaluronate (NaHA) gel within ~ 1 μm of negatively and positively charged surfaces as a function of ionic strength, which results in a change in the local network deformation and motion. We conclude that the network motion differs when swollen under different salt concentrations.