Influence of different chemical treatments on the surface of Al2O3/ZrO2 nanocomposites during biomimetic coating

Abstract

The objective of this study is to evaluate the influence of different chemical surface treatments (H 3 PO 4 , HNO 3 , and NaOH) in the formation of calcium phosphate phases on the surface of Al 2 O 3 /ZrO 2 (5 vol%) nanocomposite. For this purpose, Al 2 O 3 /ZrO 2 samples were shaped, calcined at 400°C, sintered at 1500°C, subjected to different chemical treatments, and biomimetically coated from 14 to 21 days. Surface characterization was performed by scanning electron microscopy, atomic force microscopy, confocal microscopy, X-ray diffraction, and infrared spectroscopy. It was observed that the preliminary chemical treatment favored the formation of particular calcium phosphate phases of interest, such as α-TCP (alpha-tricalcium phosphate), β-TCP (betatricalcium phosphate), and HA (hydroxyapatite). The differences among the percentages of the phases formed affected the homogeneity of calcium phosphate distribution within the nanocomposites as well as the roughness of the formed layer, effectively contributing to adhesion, proliferation, and desired cell biofixation on bone implant.

Surface modification using the biomimetic method in alumina‐zirconia porous ceramics obtained by the replica method

“…To obtain the scaffolds, AKP‐53 alumina produced by Sumitomo Chemical, Japan, were used with an average particle size of ∼0.25 μm, a specific surface area of 13.6 4m 2 /g and 99.995% pure purity, and partially nanometric zirconia (3% mol yttria, Nanostructured & Amorphous Materials Inc. MA), with a mean particle size of 50 nm, a surface area 19.8 m 2 /g and 99.9% purity. The preparation of alumina matrix powder containing 5% vol of zirconia inclusions was performed by blending suspensions according to work developed by our research group …”

“…Currently, the modification of surfaces of materials approved by the Food and Drug Administration is becoming a reality. Among these, bioceramics, used for bone replacement or repair, can be surface modified to make them bioactive . They are used to repair, regenerate and restore the functions of damaged bone tissue .…”

“…As a result, the material becomes more efficient, with a faster bone growth and a bond with the bone formed . However, for the production of bioceramics, it is essential to use a bioinert material to provide tensile and fatigue resistance, which is not the best property of bioactive materials, such as HA …”

“…Since its first formulation, the biomimetic method has undergone significant variations. Among them, is an increase in the SBF concentration, with the aim of accelerating the formation process and changes in the crystallinity of the coating …”

“…Bioceramic surfaces, chemically treated before biomimetic coating, induce the formation of negative charges, favoring the nucleation of apatite during the immersion in SBF fluid. This type of treatment has been studied by several authors . using phosphoric acid solution (H 3 PO 4 ) in order to increase the specific contact area and surface energy of the substrate, that is, to increase the adhesion on the surface of the bioinert scaffolds, facilitating apatite growth and then became then as a bioactive scaffold …”