Effective lubrication is critical to maintaining the efficient functioning and slowing the degradation of living systems. Mammalian joints are lubricated with synovial fluid, oral cavities are lubricated with saliva, and epithelial layers in the eye, respiratory airway, and gastrointestinal tract are coated with lubricating mucosal layers. Conversely, inferior lubrication is the cause of diseases such as arthritis or dry eye and is at the root of failure of medical devices such as total joint replacements and contact lenses. Beyond biology, proper lubrication is critical for the function of motors, engines, and vehicles. Increased friction accounts for up to 15% of fuel consumption in vehicles and results in 60-70 percent of resistance to motion of large ships. Thus, in addition to important applications to living systems, biology presents an excellent template for the design of lubricants that can greatly reduce energy consumption in a variety of man-made systems. This Leading Engineering for America's Prosperity, Health, and Infrastructure (LEAP-HI) interdisciplinary project will design, synthesize, and test new families of lubricants to understand and treat disease and to serve as templates for lubricating synthetic systems.

An array of lubricating behaviors in nature are mediated by mucins, glycoproteins that achieve efficient lubrication by binding with tissues via a protein backbone and attracting water to surfaces via sugar side chains. For example, the articular cartilage surface has friction coefficients as low as 0.001, lower than ice-on-ice, and is lubricated by interactions of the specialized mucin lubricin and hyaluronic acid to form a microscale lubricating layer. The project will investigate the use lubricin and hyaluronic acid and their interactions as a template for designing, fabricating, and characterizing recombinant and synthetic lubricants that lubricate and protect biological systems at multiple length scales. The goal is to: 1) develop a new generation of biolubricants using synthetic biology, glycoengineering, and biomimetic synthesis; 2) understand mechanisms of lubrication of these materials at the nano-, micro-, and macroscales; and 3) evaluate the potential of the new lubricants to treat medical conditions.

This award reflects NSF's statutory mission and has been deemed worthy of support through evaluation using the Foundation's intellectual merit and broader impacts review criteria.