Hierarchical picot-fiber hydrogel coating with ultralow friction and high wear resistance.

Abstract

Hydrogel coatings are a promising strategy to reduce friction and wear in biomedical implants, yet replicating the durability of natural cartilage remains a key challenge due to the inherent trade-off between low friction and high wear resistance. Here, we present a picot-fiber hydrogel coating (PFHC) that mimics the hierarchical architecture of cartilage by integrating a lubricious surface layer with a tough, fiber-reinforced core layer. The picot fibers, formed by folded peptide strands with hidden loops, endow the core layer with efficient load-bearing capacity, while the loosely packed, open-structured top layer preserves hydration lubrication. The resulting PFHC achieves both ultralow friction (~0.009) and high wear resistance under long-term sliding over 100,000 cycles, comparable to natural cartilage. By decoupling lubrication and load-bearing functionalities across distinct structural layers, PFHC overcomes the conventional limitations of hydrogel coatings, providing a generalizable strategy to integrate lubrication and mechanical durability for reliable, long-lasting implant interfaces.