The deposition of strontium and zinc Co-substituted hydroxyapatite coatings

Abstract

The in vitro and in vivo performance of hydroxyapatite (HAp) coatings can be modified by the addition of different trace ions, such as silicon (Si), lithium (Li), magnesium (Mg), zinc (Zn) or strontium (Sr) into the HAp lattice, to more closely mirror the complex chemistry of human bone. To date, most of the work in the literature has considered single ion-substituted materials and coatings, with limited reports on co-substituted calcium phosphate systems. The aim of this study was to investigate the potential of radio frequency magnetron sputtering to deposit Sr and Zn co-substituted HAp coatings using Fourier transform infrared spectroscopy (FTIR), X-ray diffraction (XRD) and X-ray photoelectron spectroscopy (XPS). The FTIR and XPS results highlight that all of the Sr, Zn and Sr-Zn co-substituted surfaces produced are all dehydroxylated and are calcium deficient. All of the coatings contained HPO groups, however; only the pure HAp coating and the Sr substituted HAp coating contained additional CO groups. The XRD results highlight that none of the coatings produced in this study contain any other impurity CaP phases, showing peaks corresponding to that of ICDD file #01-072-1243 for HAp, albeit shifted to lower 2θ values due to the incorporation of Sr into the HAp lattice for Ca (in the Sr and Sr-Zn co-substituted surfaces only). Therefore, the results here clearly show that RF magnetron sputtering offers a simple means to deliver Sr and Zn co-substituted HAp coatings with enhanced surface properties. (a) XRD patterns for RF magnetron sputter deposited hydroxyapatite coatings and (b)-(d) for Sr, Zn and Sr-Zn co-substituted coatings, respectively. The XPS spectra in (b) confirms the presence of a HA sputter deposited coating as opposed to

Multisubstituted hydroxyapatite powders and coatings: The influence of the codoping on the hydroxyapatite performances

“…Dual ionic substitutions can be considered as a promising strategy to improve the physicochemical and biological properties of HAp. Mostly, both of the two considered vicarious ions are cations, whereas in some cases the anion/anion and anion/cation combinations were investigated. As expected, HAp gets different physico‐chemical properties and biological performances on the basis of the vicarious ions kinds and amounts.…”

“…Sr 2+ was also co‐substituted within apatite lattice with Na + in order to obtain Sr 2+ /Na + co‐doped HAp coatings on carbon/carbon composites, with Zn 2+ and with Ag + to be deposited on cp‐Ti substrates.…”

“…Robinson et al fabricated Sr/Zn co‐substituted HAp coatings by radio frequency magnetron sputtering, comparing them to undoped, Sr‐ and Zn monodoped HAp ones. All the obtained coatings consisted of pure dehydroxylated and calcium deficient HAp, and were characterised by the groups, even if only the undoped HAp coating and the Sr substituted HAp coating contained additional groups, as demonstrated by Fourier transform infrared spectroscopy (FTIR) and X‐ray photoelectron spectroscopy (XPS) . XRD patterns of Sr and Sr‐Zn co‐substituted coatings presented a shift ot the HAp typical diffraction peaks to lower 2 θ values, due to the incorporation of Sr within HAp lattice for Ca.…”

Si, Sr, Ag co-doped hydroxyapatite/TiO2coating: enhancement of its antibacterial activity and osteoinductivity

“…17 Different trace elements (Sr, Si, Mn, Mg, CO 3 2À , F and Zn) with specic biological properties are usually found in biological apatites, which form in biological conditions. 18 The bioactivity of an implant-its antibacterial, anti-inammatory, anti-osteoporotic and angiogenic propertiescan be tuned through selected doping. 9 Several biologically active ions, such as Si and Sr, have been regarded as dopants because of their natural presence in native bone tissues and can benecially inuence the biological response of osteoblasts.…”

Thin Bioactive Zn Substituted Hydroxyapatite Coating Deposited on Ultrafine-Grained Titanium Substrate: Structure Analysis

“…The coatings were deposited by RF magnetron sputtering method. It is possible to find recent reports on the deposition of strontium and zinc Co-substituted HA coatings by Robinson et al (2017). But to our knowledge, the studies with regard to Zn containing HA coatings, especially when deposited on UFG Ti are very limited in the scientific community.…”