Study on Natural Joints: Hydrophilic and Negatively Charged Cartilage Surface effect Friction

It is a physical phenomenon for biological systems that the cartilage surface is hydrophilic and negatively charged. However, there is a lack of knowledge about some parameters possessed by cartilage surface, e.g., interfacial surface energy, amphoteric, wettability, negatively charged bilayers, and lamellar slippage. Some of these parameters will be taken from literature to support and correct Hills [1] hydrophobic lubrication model which is hydrophilic and negatively charged. Phospholipids as lubricant are highly self-organized biomolecules in aqueous media, and their structure lets them form spontaneously vesicles, lamellar phases, and bilayers (see Fig. 1). Verification of hydrophobic or hydrophilic model, the following studies have been undertaken: Interfacial energy, Friction (cartilage/cartilage) pair, and wettability cartilage surface (values measured for the air-dry surfaces).