Super-lubricous polyethylene glycol hydrogel microspheres for use in knee osteoarthritis treatments

Knee osteoarthritis (OA) is characterized by cartilage degeneration and significant reduction in lubrication. One strategy to recover the natural lubrication of the synovial fluid is the injection of hydrogel microspheres. Here, we have fabricated polyethylene glycol (PEG)-based hydrogel microspheres via a modified electrospraying setup. To improve throughout, crosslinking of PEG droplets was delayed until after droplet formation was complete. A custom-synthesized super-lubricious copolymer consisting of adhesive dopamine methacrylate (DMA), zwitterionic sulfobetaine methacrylate (SBMA), and fluorescent rhodamine B was used to dip-coat the PEG microspheres. Super-lubricious PEG microspheres coating reduced coefficient of friction by 57% compared to simulated synovial fluid, indicating beneficial lubrication properties. When injected into C57BL6 mice, PEG microspheres exhibited stability for up to 26 d and did not adversely affect mouse behavior. These super-lubricious PEG microspheres offer great promise to reduce the friction that is a hallmark of progressive OA, potentially mitigating the need for total knee arthroplasty.