Proposal Of A New Method For EvaluatingThe Frictional Properties Of TissueEngineered Cartilage

It is essential to investigate the tribological maturation of tissue engineered cartilage that is to be used in medical applications. The friction properties of tissue engineered cartilage have been measured using flat counter surfaces such as stainless steel, glass or ceramics. However, the measured friction properties were significantly inferior to those of natural cartilage, likely because of cartilage adhesion to the counter surface. In this study, a poly(2-methacryloyloxyethyl phosphorylcholine (MPC)) grafted surface is proposed as an appropriate counter surface for cartilage friction evaluation due to the material’s ability to reduce the adhesion and reproduce natural tribological conditions. The poly(MPC) grafted surfaces were prepared by atom transfer radical polymerization (ATRP). The friction coefficients for natural cartilage that were measured on the poly(MPC) grafted surface were lower than 0.01 at the sliding velocities of 0.08 and 0.008 mm/s, which is equivalent to that for natural cartilage-on-cartilage. The friction coefficients for the tissue engineered cartilage were reduced with cultivation time at low sliding velocities. Thus it is suggested that the proposed system is able to measure the tribological maturation of tissue engineered cartilage in a more natural lubricating environment.