Nanoparticle formulation for intra-articular treatment of osteoarthritic joints

Based on a proven concept of using nanoparticles to lubricate an articulating interface, we developed a set of formulations to demonstrate the feasibility of using polymeric nanoparticles as physical intervention for early stage osteoarthritis (OA). The biocompatible polymeric nanoparticles (NPs), namely polymethylmethacrylate (PMMA), polycaprolactone (PCL), and polylactic acid (PLA) were accompanied with hyaluronic acid (HA) and surface actives, of which the lubrication effect was examined between a steel ball and a silicone elastomer substrate to replicate the bone-cartilage contact. All three types of polymer nanoparticles were found to reduce the overall Coefficient of Friction (CoF), with PLA NPs being the most effective - providing a reduction up to 24.3%, which suggests that soft (low Young's modulus) nanoparticles are the most efficient frictional additives. Based on the data acquired, it is likely that surface deposited NPs could smooth the solid substrates, hyaluronic acid ensures bulk viscosity, and the surfactant enhances formulation stability. We suggest that surface adsorbed nanoparticles are beneficial in providing interfacial lubrication, which offers insight on the development of early stage intervention strategies for OA.