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Abstract
The electrokinetic properties of intact wet bovine femur cortical bone plugs were examined through streaming potential experiments. Mechanical properties of machined dumbbell bovine femure samples were also examined in uniaxial tension. Knowledge gained about the relationship between bone constituents (inorganic bone mineral and organic components) was employed in the tension experiments to examine the interfacial bonding forces between bone constituents and their role in the mechanical properties of bone tissue.
Electrokinetic experimental results reveal a compartmental model for electrokinetic potentials in intact bone tissue. Unique zeta potentials due to fluid flow in bone are associated with the vascular channel system, examined in streaming potential experiments, and with the calcified matrix, investigated in particle electrophoresis.
Streaming potential results indicate the organic constituents dominate the electrokinetic properties of bone under physiological conditions. The vascular channel system is lined with organic material that "shields" the mineral from the fluid phase. These organic linings limit ion penetration to the bone mineral surface, which strongly adsorbs the organic material.
The organic layers in the vascular channel system can be removed through the use of a nonionic surfactant. The removal of some of the organic linings allows ions to access the mineral-organic interface. This results in an alteration in both the electrokinetic and mechanical properties of bone.
Potential determining ions and specifically adsorbed ions were used to examine the interfacial bonding between bone constituents on the mechanical properties. Data indicates that phosphate and fluoride ions can alter the interfacial bonding between the mineral and organic components leading to a decrease in the mechanical properties.
