Influence of a cellulosic ether carrier on the structure of biphasic calcium phosphate ceramic particles in an injectable composite material

An injectable composite material based on biphasic calcium phosphate (BCP) and a nonionic cellulose ether has been elaborated for use in percutaneous surgery for spine fusion. This paper reports the characterization results o f this material by spectroscopic techniques including X-ray diffraction (XR D), infrared spectroscopy (FTIR), X-ray photoelectron spectroscopy (XPS), s canning electron microscopy (SEM) fitted with an energy dispersive X-Ray an alysis system and high-resolution transmission electron microscopy (HR-TEM) . From FTIR and XPS results, it was observed that the adhesion between the polymer and the ceramic might be insured by oxygen bridging developed throu gh an ionic bonding between calcium ions and (C-O) groups of the polymer. M oreover, XPS showed attraction of Ca2+ ions in the polymer matrix, while th e ceramic surface was modified in a HPO42--rich layer. These results sugges t a possible dissolution/precipitation process at the interface ceramic/pol ymer. HR-TEM observations supported this hypothesis, showing a light contra sted fringe at the surface of the ceramic grains in the composite paste. As well, changes in the XRD spectra could indicate a small decrease in the cr ystal size of the BCP powder through the contact to polymer solution. In ad dition, SEM observation showed a decrease of the initial BCP granulometry. Aggregates of 80-200 mu m seemed to be mostly dissociated in micrograins. T he ceramic grains were coated with and bonded between each other by the pol ymer matrix, which acted as spacer in between the ceramic grains, creating a macroporous-like material structure. (C) 1999 Elsevier Science Ltd. All r ights reserved.