Interaction of a blood coagulation factor on electrically polarized hydroxyapatite surfaces

Although the polarization treatment of hydroxyapatite (HA) remarkably enhances the osteoconductivity, the mechanisms have not yet been completely understood. The interaction of proteins in blood and tissue fluids with biomaterials are reportedly triggers for later cellular responses and played a major role in osteoconductive processes. Considering this, we disclosed the interaction of polarized HA surface with a coagulation factor, fibrin stabilizing factor XIII (FXIII). The HA activated FXIII even in Ca 2+ free buffer, based on the SDS‐PAGE detections of α‐polymer and γ‐dimer bands assigned to stabilized fibrin. The Ca 2+ ions, possibly released from the HA surfaces, were examined whether they initiate the activation of the FXIII. It was experimentally proved by ICP analysis that the induced large negative charges on the electrically polarized HA significantly increased the released Ca 2+ concentration for the short pre‐incubation time of 3 min. The more Ca 2+ ions released from the negatively charged HA (N‐HA) surfaces were more effective in the activation of the FXIII, resulting in the rapider disappearance of the γ‐chain bands in fibrin. The slightly lower Ca 2+ concentration in the positively charged HA, compared to the nonpolarized HA activated the FXIII at an almost equal rate. The accelerated activation contributed to the stabilization of fibrin scaffold. Therefore, the polarity difference of the induced charges of the polarized HA surface altered the rate of the FXIII activation. The early stage interaction of the HA surfaces with blood proteins was considered to be an essential process of the accelerated new bone formation near implanted N‐HA surface. © 2006 Wiley Periodicals, Inc. J Biomed Mater Res Part B: Appl Biomater, 2006