(635b) Robust Nanoscale Liposome Based Coatings On Silk Microspheres Exhibit Exceptionally Low Friction Coefficients for Application in Articular Joints

We present recent  results of our work to develop a robust nanoscale liposome based coating on silk microspheres to couple the lubrication properties of highly hydrated phospholipid head groups with the cushioning effects and wear resistance of silk. Such microscale ball bearings with low coefficients of rolling friction have significant potential in injectable systems for joint lubrication and show a high degree of wear resistance even at load levels that are orders of magnitude above those experienced in articular joints.  The concept has also been extended to systems of thin silk films covered with a dense packed layer of liposomes which are “captured” and tethered in place using chitosan based biopolymers. Such systems exhibit coefficient of friction values representative of articular joints (0.008 and lower), indicating their potential efficacy as coatings for implant materials.  Such synergies between phospholipids to provide the requisite hydration layers for enhanced slippage, and biopolymers to provide the cushioning and wear resistance will be discussed. With current therapeutic options of improving joint comfort being limited, these systems indicate new directions in materials for enhanced biolubrication.