Magnetic field response of aqueous hydroxyapatite based magnetic suspensions.

During the biomedical and biotechnological applications of hydroxyapatite based magnetic biomaterials the response to various magnetic fields (i.e. change in flow behavior) plays a pivotal role in manipulating these materials. Numerous studies discuss the synthesis, characterization and possible applications of magnetic hydroxyapatite, however the number of reports related to the magnetic response is limited. In this study we investigated the response of aqueous suspensions of magnetite/hydroxyapatite composites with gelatin as an additive to homogeneous and inhomogeneous magnetic fields. Under homogeneous field the change in rheological properties was determined, and correlated with the composition of the composites. The effect of magnetite and gelatin content on the zero field viscosity and magnetic susceptibility were also evaluated. The response to inhomogeneous field was characterized by measuring the magnetic body force acting on droplets of the aqueous suspensions. We found that the formulation of the composites and the presence of additive largely affect the magnetic response.