Biomimetic mineralization of calcium phosphate on a functionalized porous silicon carbide biomaterial

Abstract

Porous biomorphic silicon carbide (bioSiC) is a structurally realistic, high-strength, and biocompatible material which is promising for application in load-bearing implants. The deposition of an osteoconductive coating is essential for further improvement of its integration with the surrounding tissue. A new strategy towards biomimetic calcium phosphate coatings on bioSiC is described. X-ray photoelectron spectroscopy (XPS) analysis shows that using 10-undecenoic acid methyl ester a covalently bound monolayer can be synthesized on the surface of the bioSiC. After hydrolysis it exposes carboxylic acid groups that promote the selective nucleation and growth of a very well-defined crystalline layer of calcium phosphate. The resulting calcium phosphate coating is characterized by X-ray diffraction and electron microscopy techniques. Further, ion beam imaging is employed to quantify the mineral deposition meanwhile, three-dimensional dual-beam imaging (FIB/SEM) is used to visualize the bioSiC/mineral interface. The monolayer is show to actively induce the nucleation of a well-defined and highly crystalline mixed octacalcium phosphate/hydroxyapatite (OCP/HAP) coating on implantable bioSiC substrates with complex geometry. The mild biomimetic procedure, in principle, allows for the inclusion of bioactive compounds that aid in tissue regeneration. Moreover, the mixed OCP/HAP phase will have a higher solubility compared to HAP, which, in combination with its porous structure, is expected to render the coating more reabsorbable than standard HAP coatings. © 2012 Wiley-VCH Verlag GmbH& Co. KGaA, Weinheim.