Sustainable superlubricity achieved by thermosensitive and degradable hydrogel under ocular conditions

Sustainable lubrication of biomedicine hydrogels with high stability is important for their application in dry eye disease (DED) treatment, remaining challenge to achieve. We report a novel strategy to achieve sustainable superlubricity under ocular conditions based on the degradation of the thermosensitive P-C_nPEG hydrogel. Firstly, through adjusting the composition and chemical structure of P-C_nPEG complex, its aqueous solution undergoes an adaptive sol-to-gel transition at 25.1 °C during heating, forming a gel state upon injection onto the ocular surface (35 °C). Besides, the obtained P-C_nPEG hydrogel at 35 °C also shows superior performance, such as shear resistance, high transmittance (> 80%), rapid swelling, self-healing and Ca²⁺ responsiveness, making it well suitable for ocular applications. Then, in the tear environment of DED patients with high reactive oxygen species (ROS) content, P-C_nPEG hydrogel degrades within 6 days through the broken of the crosslinking sites. Degradation solution of each day presents ultra-low coefficients of friction (COF) under ocular conditions through the hydration effect. Finally, the excellent biocompatibility of the hydrogel demonstrates its potential for ocular applications. This study systematically discusses the mechanism of sustainable degradation-induced superlubricity of P-C_nPEG hydrogel, introducing a novel and promising strategy for DED treatment.