Bone cell-material interactions on metal-ion doped polarized hydroxyapatite

The objective of this work is to study the influence of Mg(2+) and Sr(2+) dopants on in vitro bone cell-material interactions of electrically polarized hydroxyapatite [HAp, Ca(10)(PO(4))(6)(OH)(2)] ceramics with an aim to achieve additional advantage of matching bone chemistry along with the original benefits of electrical polarization treatment relevant to biomedical applications. To achieve our research objective, commercial phase pure HAp has been doped with MgO, and SrO in single, and binary compositions. All samples have been sintered at 1200 degrees C for 2 h and subsequently polarized using an external d.c. field (2.0 kV/cm) at 400 degrees C for 1 h. Combined addition of 1 wt.% MgO/1 wt.% SrO in HAp has been most beneficial in enhancing the polarizability in which stored charge was 4.19 mu C/cm(2) compared to pure HAp of 2.23 mu C/cm(2). Bone cell-material interaction has been studied by culturing with human fetal osteoblast cells (hFOB) for a maximum of 7 days. Scanning electron microscope (SEM) images of cell morphology reveal that favorable surface properties and dopant chemistry lead to good cellular adherence and spreading on negatively charged surfaces of both Sr(2+) and Mg(2+) doped HAP samples over undoped HAp. MTT assay results at 7 days show the highest viable cell densities on the negatively charged surfaces of binary doped HAp samples, while positive charged doped HAP surfaces exhibit limited cellular growth in comparison to neutral surfaces. (C) 2011 Elsevier B.V. All rights reserved.