Investigation of the lubrication properties and synergistic interaction of biocompatible liposome-polymer complexes applicable to artificial joints.

• Liposomes with increasing carbon chain length reveal excellent lubrication. • The bilayers weaken the stability of vesicles and exhibit increased friction. • Lipid complexes led to the formation of a remarkable boundary lubrication layer. • Lipid complexes can efficiently improve the lubrication properties of liposomes. Achievement of efficient biolubrication is essential for the design of artificial joints with long lifetimes. This study examines the frictional behaviors and adsorption structures of liposomes and liposome complexes with biocompatible polymers to reveal the underlying lubrication mechanisms between biomimetic bearing surfaces of polyetheretherketone (PEEK) and silicon nitride (Si 3 N 4). The liposomes with increasing carbon chain lengths exhibit the remarkable lubrication capabilities that correlate strongly with the structural integrity of small unilamellar vesicles adsorbed on the Si 3 N 4 surfaces, while the bilayer structures weaken the stability of vesicles against rupture and cause the increase of friction. The synergistic interaction of liposomes and biocompatible negative-charged polymer leads to the formation of a boundary–lubricating layer with high-density liposome–polymer complex structures that can efficiently improve the lubrication properties of liposomes. Our findings might have implications for future biolubrication investigations on biocompatible liposome–polymer complexes applicable to artificial joints at the specified macroscale conditions. [ABSTRACT FROM AUTHOR]