Physicochemical characterization of zinc-substituted calcium phosphates

Abstract

Biocompatible and bioactive calcium phosphates can make chemical bonds with living bones. Improvement of their biological and physicochemical properties can be achieved by doping with various ions that are presented in natural apatites of bones. These substitutions influence lattice parameters, structure and morphology of apatites. In recent times great attention has been devoted to zinc ions that are the second most abundant trace element present in bones. Zinc embedded into calcium phosphate may enhance the bone formation and in addition exhibits antifungal and antibacterial properties. Therefore, it is rational to form structures incorporated with this ion. In this paper the incorporation of the Zn ions into natural and synthetic calcium phosphates has been reported. Natural hydroxyapatites (HAs) applied in this study were derived mainly from pork bones whereas both brushite and synthetic were formed using wet chemical methods. Ambient temperature synthesis leads to the formation of brushite, whereas the process performed at elevated temperature gives HA. Subsequently, attained structures were modified with Zn ions by using in situ or sorption procedures. Phase composition and morphology of obtained materials were determined by means of X-ray diffractometry, Fourier transform infrared spectroscopy and scanning electron microscopy equipped with energy-dispersive spectroscopy. Introduced XRD patterns depict changes of the crystallinity of HA with the increase in the amount of embedded zinc ions. On the contrary, no changes of the crystallinity were observed for the brushite doped with Zn ions. Morphology of attained powders, visualized using scanning electron microscopy exemplified structural changes between calcium phosphates conjugated with zinc ions. Many authors report that the addition of small amounts of Zn ions leads to loss of crystallinity and decrease of lattice parameters. Interestingly, upon addition of Zn ions to the natural and synthetic HAp by sorption procedures no crystallographic and structural changes were observed. Notably, upon increase of zinc ions also structure of brushite formed by the in situ method remains constant, indicating no influence of added ions. Our outstanding finding promotes sorption procedure as suitable route to form structures incorporated with various ions that can be further employed as potential implants.

Improved cytocompatibility and antibacterial properties of zinc-substituted brushite bone cement based on β-tricalcium phosphate

“…Previous research showed the possibility of replacing calcium in calcium phosphates with Zn ions. In [ 31 ], the preparation and physical-chemical characterization of Zn-substituted calcium phosphate powders was performed. Authors [ 31 ] demonstrated that up to about 10 at.% (about 15 wt%) of Zn ions do not significantly influence the crystal lattice of HA and brushite, whereas authors [ 32 ] showed that Zn can replace calcium in the β-TCP structure up to about 10 at.% with the preference of the Ca(5) site.…”

Characterization and biological properties of a novel synthesized silicon-substituted hydroxyapatite derived from eggshell

“…9,10,[28][29][30] These results provide appropriate situations and capacities for this kind of biomaterial in terms of clinical practice. Therefore, it is worth to mention that although some valuable works related to e-HA and also Si-HA 9,13,18,20,21,[24][25][26][27][28][29][30][31][32][33][34][35] have been done, no study has accomplished to investigate the effect of adding silicon in the structure of e-HA on physical and mechanical properties besides cellular (osteosarcoma cell line: G-292) and antibacterial behaviours using proper analytical techniques such as X-ray diffraction (XRD), X-ray fluorescence (XRF), scanning electron microscope (SEM)/field-emission scanning electron microscope (FE-SEM), inductively coupled plasma (ICP) and Fourier transform infrared (FTIR). For this purpose, e-HA and Si-e-HA were prepared by chemical precipitation method.…”

Biomimetic Collagen/Zn2+-Substituted Calcium Phosphate Composite Coatings on Titanium Substrates as Prospective Bioactive Layer for Implants: A Comparative Study Spin Coating vs. MAPLE

“…Accordingly, an excess in the Zn 2+ concentration results in an enhanced saturation of apatite units. More Ca 2+ ions are replaced by Zn 2+ , promoting smooth diffused areas in both phosphate region and amide section [29].…”