Glucose-Responsive Superlubricity of a Self-Healing Hydrogel Containing Dynamic Boronic Ester Bonds under Ocular Conditions

Dry eye disease (DED) is a widespread ocular disorder that poses a growing threat to global eye health and creates a requirement for stable ocular lubrication. In this study, a strategy for achieving ocular superlubricity is proposed based on the reaction between a P-C2PEGOH hydrogel and glucose in artificial tears. The dynamic boronic ester bonds in the P-C2PEGOH hydrogel undergo a reversible competitive exchange reaction with glucose, leading to the dissociation of original cross-linking points and the release of hydrophilic polyethylene glycol (PEG)-based substrates. Both results of the reaction endow the hydrogel with glucose-responsive superlubricity. Friction tests show that the release of PEG-based substrates reduces the coefficient of friction (COF) of artificial tears from 0.0078 to 0.0037. PEG-based substrates form hydration layers that reduce shear stress of the interface through the hydration lubricating effect. Through varying the glucose concentration, the level of PEG-based substrates in the tears and the hydration capacity on the hydrogel surface can be modulated, thereby enabling glucose-responsive superlubricity. Furthermore, the presence of dynamic boronic esters containing boron-nitrogen coordination bonds endows the hydrogel with a self-healing capability, enabling it to recover its structural integrity after mechanical disruption. Moreover, cytotoxicity assays and in vivo biocompatibility evaluations confirm the biocompatibility of the hydrogel, highlighting its potential for ophthalmic applications.