Ph.D Thesis

Ph.D StudentNimer Emad
SubjectSolute Transport and Kinetics of Binding in Cartilage
with and without Applied Static Compression
DepartmentDepartment of Biomedical Engineering
Supervisor PROF. Alice Maroudas


We describe experimental apparatus, methods and mathematical algorithms to determine diffusion and partitioning of typical nonbinding small, medium and large solutes in statically loaded cartilage. We also offer a method and mathematical algorithms to extract the kinetics coefficients of binding reaction of protein, "free" diffusion coefficient of unbound protein and the distribution of proteins through the aqueous and solid phase in both loaded and unloaded cartilage. Our theoretical interpretation of the results is that the partition coefficient (K) can be expressed as a function of fixed charge density (FCD).        For ions the partition coefficient shows good agreement with the ideal Gibbs-Donnan equilibrium, particularly when FCD is based on extrafibrillar water (EFW).  For small solutes the diffusion coefficient () is highly correlated with the fraction of fluid volume in the tissue. These experimental results show good agreement with the simple geometrical model of Mackie and Meares. For large nonbinding solutes K & show some agreement with a modified Ogston model based on two major components, viz., glycosaminoglycans and core protein.

            Proteins exhibit a first order reaction with high affinity for the cartilage matrix. K  & D of proteins is complicated by binding to the solid components of the matrix and depends on a number of factors such as protein charge, concentration, ionic strength of the solution and FCD of the matrix. Under static compression binding to the solid phase is the dominant factor controlling the uptake and movement of proteins in cartilage.