Liposomes are vesicles formed by natural lipids commonly named phospholipids. Phospholipids contain the phosphocholine head group which has great impact on their characteristics. In general the use of natural lipids provides biocompatibility; liposomes are frequently used as drug delivery agents, and we now propose to use them for bio-lubrication purposes. Our phosphatidylcholine liposomes, which are in their more rigid gel phase, form close-packed boundary layers in a hydrated environment. This leads to a striking reduction of the friction coefficient at high pressures because the uniform close-packed arrangement of these liposomes creates a particularly robust layer. These characteristics make these liposomes excellent candidates for use as boundary lubricant materials.
Bio-lubricant materials for:
• Medical applications such as reduction of skinsoreness from rubbing and suppression of plaque formation, and in biomedical devices including catheters
• Cosmetic applications such as use in conditioners and shampoos
• Friction reducers in synovial joints where osteoarthritis-related problems arise
• Rapid and simple liposome preparation procedure
• Strong decrease of friction coefficient at physiological pressures
• Material robustness and stability
Our phosphatidylcholine liposomes spontaneously adsorb and self-assemble onto a solid surface in aqueous solution to form a robust boundary layer which provides extremely efficient lubrication at the interfaces. The lubrication occurs under pressures of up to 100 atmospheres or more. These characteristics are preserved up to the gel-to-liquid-crystalline phase transition temperature (Tm= 53ºC for the HSPC liposomes for example). The lipids head groups which are highly hydrated and exposed at the outer liposome surfaces provide these remarkable properties by virtue of the hydration lubrication mechanism.