Self-renewing nanoparticles reduce friction and joint wear

In an experiment using models of knee and jaw osteoarthritis, researchers tested a multifunctional nanoparticle system designed to treat mechanically aggravated joint degeneration. Friction and oxidative inflammation together advance age-related cartilage loss. Under physical movement, the nanoparticles partially dissociate to spread a lubricated layer, then spontaneously reassemble when movement stops. This cycle maintained ultralow friction under repeated loading, achieving a greater than 90% lower coefficient of friction than commercial hyaluronic acid. In inflammatory joints, oxidative molecules triggered targeted drug release. The treatment reduced the inflammatory proteins IL-6 and IL-1β, reversed chondrocyte senescence—a state where cartilage cells stop dividing—and protected the extracellular matrix. In a load-driven knee model and a frequency-driven jaw joint model, the nanoparticles preserved cartilage, suppressed inflammation, and improved joint shape.