In the subfield of cartilage tribology, we have recently embarked on a new, major research direction. In this research, we use nanotribomechanical measurements on model surfaces and cartilage from genetically engineered mice, combined with several surface-specific physicochemical measurements, to determine the mechanisms by which glycoproteins (such as PRG4 and its product, lubricin) provide lubrication and wear-protection in diarthrodial joints. Our research contributes significantly to the understanding of the mechanisms by which PRG4 mediates normal and friction forces in articular cartilage, in absence of fluid pressurization. Identification of these mechanisms is essential for the development of new treatments, such as tribosupplementation, that exploit mechanical and biochemical modalities for the prevention of disease. In a broader perspective, this research is expected to add significantly to the growing knowledge of biotribology, and the interaction of biomacromolecular polyelectrolytes with natural and man-made surfaces.

SA1: Understand the effect of lubricin on steric, friction and adhesion forces on: (i) the molecular level, using model surfaces that mimic the cartilage surface chemically, and (ii) the tissue level, using a PRG4(-/-) mouse model.

SA2: Assess the implications of lubricin deficiency on the local biomechanical properties of cartilage.