Tough, Slippery,\nand Low-Permeability Multilayer Hydrogels\nModified by Anisotropic Fiber Membrane for Soft Tissue Replacement

Hydrogels with sustained lubrication, high load-bearing\ncapacity,\nand wear resistance are essential for applications in soft tissue\nreplacements and soft material devices. Traditional tough or lubricious\nhydrogels fail to balance the lubrication and load-bearing functions.\nInspired by the gradient-ordered multilayer structures of natural\ntissues (such as cartilage and ligaments), a tough, smooth, low-permeability,\nand low-friction anisotropic layered electrospun fiber membrane-reinforced\nhydrogel was developed using electrospinning and annealing recrystallization.\nThis hydrogel features a stratified porous network structure of varying\nsizes with tightly bonded interfaces, achieving an interfacial bonding\ntoughness of 1.6 × 10<sup>3</sup> J/m<sup>2</sup>. The anisotropic\nfiber membranes, mimicking the orderly fiber structures within soft\ntissues, significantly enhance the mechanical properties of the hydrogel\nwith a fracture strength of 20.95 MPa, a Young’s modulus of\n29.64 MPa, and a tear toughness of 37.94 kJ/m<sup>2</sup> and reduce\nits permeability coefficient (6.1 × 10<sup>–17</sup> m<sup>4</sup> N<sup>–1</sup> s<sup>–1</sup>). Meanwhile,\nthe hydrogel demonstrates excellent solid–liquid phase load-bearing\ncharacteristics, which can markedly improve the tribological performance.\nUnder a contact load of 4.1 MPa, the anisotropic fiber membrane-reinforced\nhydrogel achieves a friction coefficient of 0.036, a 219% reduction\ncompared with pure hydrogels. Thus, the superior load-bearing and\nlubricating properties of this layered hydrogel underscore its potential\napplications in soft tissue replacements, medical implants, and other\nbiomedical devices.