Interaction of Cartilage Biopolymers

Summary Aggrecan is a charged biopolymer whose complexes with hyaluronic acid provide the compressive resistance of cartilage. In cartilage extracellular matrix aggrecan‐hyaluronic acid complexes are enmeshed within a network of collagen fibrils. Osmotic pressure measurements and small angle neutron scattering (SANS) measurements are reported on solutions of aggrecan and aggrecan‐hyaluronic acid complexes. These techniques probe the length scales relevant to the biological functions of cartilage. Osmotic pressure measurements indicate that dissolved aggrecan monomers form microgel‐like assemblies. The osmotic pressure of aggrecan‐hyaluronic acid complexes decreases with decreasing the ratio of aggrecan to hyaluronic acid. SANS reveals that there is no significant interpenetration between the neighboring aggrecan molecules. Both osmotic pressure measurements and SANS indicate weak interactions between the aggrecan bottlebrushes and collagen fibers.