Superlubricity of Double-Network Hydrogels Modified With Tween 80 and Hydrogenated Soybean Phosphatidylcholine

Abstract

Artificial joint cartilage materials are central to arthroplasty for the treatment of osteoarthritis. Hydrogels are highly promising materials for fabricating artificial cartilage owing to their excellent biocompatibility and lubricity. Inspired by natural articular cartilage, in this study, we designed a modification strategy to enhance the lubricity of double-network (DN) hydrogels. Specifically, two lubricating substances, nonionic surfactant Tween 80 and hydrogenated soybean phosphatidylcholine (HSPC), were incorporated into a DN hydrogel. Lubricity-enhanced DN hydrogel exhibited superlubricity through the synergistic effect of Tween 80 and HSPC, with a low coefficient of friction of 0.008, which remained stable after 6 h of continuous tribological testing. In addition, the mechanical properties of lubricity-enhanced DN hydrogel were greater than those of unmodified DN hydrogel, with a 29% increase in fracture strain and a 1.7-fold increase in toughness. Tween 80 micelles reinforced the physically cross-linked network through hydrogen bonding with the DN hydrogel, whereas HSPC vesicles encapsulated in the polymer network served as reinforcement nodes to enhance the chemically cross-linked network. As a result, lubricity-enhanced DN hydrogel exhibited both excellent lubricity and mechanical properties. This study demonstrates an innovative way to design hydrogels exhibiting both superlubricity and excellent mechanical properties, broadening the applications of DN hydrogels in the field of artificial joint cartilage.