In this report, we demonstrated the formation of a biomimetic mineralizing layer obtained on the surface of dental enamel (biotemplate) using bioinspired nanocrystalline carbonate-substituted calcium hydroxyapatite (ncHAp), whose physical and chemical properties are closest to the natural apatite dental matrix, together with a complex of polyfunctional organic and polar amino acids. Using a set of structural, spectroscopy, and advanced microscopy techniques, we confirmed the formation of a nanosized ncHAp-based mineralized layer, as well as studying its chemical, substructural, and morphological features by means of various methods for the pretreatment of dental enamel. The pretreatment of a biotemplate in an alkaline solution of Ca(OH)2 and an amino acid booster, together with the executed subsequent mineralization with ncHAp, led to the formation of a mineralized layer with homogeneous micromorphology and the preferential orientation of the ncHAp nanocrystals. It was shown that the homogeneous crystallization of hydroxyapatite on the biotemplate surface and binding of individual nanocrystals and agglomerates into a single complex by an amino acid booster resulted in an increase (~15%) in the nanohardness value in the enamel rods area, compared to that of healthy natural enamel. Obtaining a similar hierarchy and cleavage characteristics as natural enamel in the mineralized layer, taking into account the micromorphological features of dental tissue, is an urgent problem for future research.
We consider two amorphous multilayer nanostructures (MLNS) [(Co 45 Fe 45 Zr 10 )/a-Si: H] 41 -I and [(Co 45 Fe 45 Zr 10 ) 35 (Al 2 O 3 ) 65 /a-Si:H] 41 -II that were obtained by ion-beam sputtering. For determination of the phase composition of the buried amorphous silicon interlayers in these MLNS, we used nondestructive ultrasoft X-ray emission spectroscopy technique (USXES). The use of the USXES enables to register the silicon Si L 2,3 -spectra providing the information about the local partial densities of Si s and d occupied states of silicon valence band in silicon-contained materials. According to the simulation and fitting procedure to the experimental data, Fe 3 Si and a small amount of oxide (SiO 2 :H) were found in the interlayer of MLNS-I. At the same time, the content of silicon dioxides (SiO 2 ) decrease from surface layers to the deep ones. On the other hand, simulation of the phase composition of MLNS-II reveals the presence of the silicides Fe 3 Si and Co 2 Si, oxides SiO 2 and SiO 1.3 , and a small amount of a-Si:H. The percentage of cobalt silicide Co 2 Si and suboxide SiO 1.3 increased in the deep layers of the MLNS-II. KEYWORDS interfaces, ion-beam sputtering, multilayer nanostructures, silicides of 3d metals, silicon oxides, ultrasoft X-ray emission spectroscopy
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