Application of a new streaming potential device on phosphate treated bovine bone particles: a reversibility study

Phosphate ions have been shown to alter the mechanical properties of bovine bone. Reduced mechanical properties have been attributed to phosphate's ability to disrupt the bonding at the mineral-organic interface. Electrokinetic and chromatographic studies have provided evidence that phosphate ions can disrupt interfacial bonding by competing with carboxyl groups for the calcium sites on the mineral phase. The authors have previously demonstrated that the effects of phosphate are reversible mechanically. The main objective of this study was to determine whether phosphate induced alterations at the mineral-organic interface are also electrokinetically reversible after prolonged treatment at various pHs. Electrophoresis, the traditional electrokinetic technique used for obtaining zeta potentials of particles, can provide only one datum per particle and is limited in the range of particle sizes that can be analyzed. A streaming potential device which accommodates a small quantity (0.5 g) of particles was developed in the authors' laboratory that can provide the average zeta potential from a continuous range of bovine bone particles (2-700 /spl mu/m) concurrently. Zeta potentials derived from a large range of particle sizes have the advantage of statistical generalizability, which is particularly important in the analysis of the complex myriad of interfaces exposed in physically disrupted bovine bone. Thus, in addition to determining the zeta of phosphate treated intact bovine bone, this study was used to determine the feasibility of employing this device by comparison to previously published electrophoresis data.