Apatite-inducing Ability Research Articles

Microstructure and surface performance of hydroxyapatite-modified multilayer amorphous coating on Ti-rich TiNbZrSn medium entropy alloy: A comparative study

The present study focuses on the formation of a hydroxyapatite-modified amorphous micro-arc oxidized (MAO) coating on the TiNbZrSn medium entropy alloy (TNZS MEA) through micro-arc oxidation and microwave hydrothermal treatment (MHT). The TNZS MEA primarily consists of a body-centered cubic (bcc) and hexagonal closed-packed (hcp) structure, exhibiting a low elastic modulus and high yield strength. A porous coating with an amorphous structure was obtained after MAO treatment, displaying superior corrosion resistance to MAOed Ti. After MHT, the MAOed TNZS MEA exhibited a multilayered structure consisting of three layers: an external growth layer (hydroxyapatite nanorods), an inner layer (amorphous and crystalline structures), and a substrate layer. This composite structure demonstrated enhanced superior apatite-inducing ability and corrosion resistance compared to MHTed Ti. The improvement in bioactivity and a slight decrease in corrosion resistance can be attributed to the incomplete structure of hydroxyapatite nanorods when compared to MHTed Ti. Consequently, this work successfully achieved a hydroxyapatite-modified multilayered oxidized coating with gradient performance in term of bioactivity and corrosion resistance, establishing it as a promising candidate material for hard tissue repair.

Effect of annealing and build direction on microarc oxidation coatings and its apatite induction ability of Ti6Al4VE alloy manufactured by selective laser melting

Effect of annealing and build direction on microarc oxidation coatings and its apatite induction ability of Ti6Al4VE alloy manufactured by selective laser melting

Effect of strontium-doped coating prepared by microarc oxidation and hydrothermal treatment on apatite induction ability of Ti13Nb13Zr alloy in vitro

Effect of strontium-doped coating prepared by microarc oxidation and hydrothermal treatment on apatite induction ability of Ti13Nb13Zr alloy in vitro

Multifaceted Ag-alloyed α-Ta5Si3 nanostructured coating for high-performing bioimplants

With the growth of the elderly population worldwide especially in developed countries, bioimplants with a multifunctional surface that embraces self-sterilizing trait, biocompatibility with mammalian cells, favorable bioactivities and high wear/corrosion resistance are in acute need. To meet such demand, the Ag-containing nanostructured α-Ta 5 Si 3 coating was fabricated onto Ti6Al4V alloy via double cathode glow discharge method. The effect of Ag addition on the mechanical properties of α-Ta 5 Si 3 was analyzed using first-principles calculations. The as-deposited α-(Ta 0.85 Ag 0.15 ) 5 Si 3 coatings consist of equiaxed nanocrystallites and greatly enhance the surface hardness of Ti6Al4V alloy. Moreover, the electrochemical characteristic, apatite-inducing ability, biocompatibility and antimicrobial trait of the α-(Ta 0.85 Ag 0.15 ) 5 Si 3 coatings were systematically studied for potential orthopedic application. The new coatings were found to remarkably reduce the corrosion damage of Ti6Al4V alloy in Ringer's solution. The coatings also promoted the formation of bone-like apatite layers and have a beneficial effect on MC3T3-E1 cells functions, including adhesion, spreading and proliferation. Ag alloying markedly increased the antibacterial capacity of the α-Ta 5 Si 3 coating against both Escherichia coli ( E. coli ) and Staphylococcus aureus ( S. aureus ) strains, and the released Ag ions were found to enhance antibacterial performance. Therefore, a unique combination of diverse functional traits makes Ag-alloyed α-Ta 5 Si 3 coating an attractive choice in the design of next-generation biomedical implants for aging population. • The (Ta 0.85 Ag 0.15 ) 5 Si 3 coating improves biocorrosion resistance of Ti-6Al-4 V alloy. • Ag addition enables the antibacterial activities of the coating against both E. coli and S. aureus . • The (Ta 0.85 Ag 0.15 ) 5 Si 3 coating enhances the cytocompatibility and in vitro bioactivity of Ti-6Al-4V alloy. • Ag ion release plays a major role in the antibacterial performance of the coating.

Rapid structural evolution and bone inducing mechanism of the multilayer coating with silicon-doped hydroxyapatite crystals on the microwave water steaming-hydrothermally treated titania coating

To reveal the formation mechanism of new bone tissues induced by the multilayer titania coating with silicon-doped hydroxyapatite (Si-HA), plasma electrolyte oxidation (PEO) and microwave steam-hydrothermal treatment (MG) were performed to form Si-HA nanorods rapidly on the PEO coating. In the present work, the length and diameter of Si-HA nanorods on the MG-treated PEO coating for 10 min (PEOMG10) were smaller than that those treated for 60 min (PEOMG60). The microstructure of the multilayer coating, including the porous middle layer containing anatase nanocrystal cluster, the middle anatase layer, Si-HA nanocrystals, and the outermost layer that grew Si-HA nanorods, was revealed by transmission electron microscopy (TEM). The in vitro mineralization test indicates that the PEOMG60 sample exhibits excellent apatite-inducing ability because of its high degradation. The in vivo animal experiment showed that the PEOMG10 implant has high interfacial bonding strength and excellent osseointegration interface status. The fracture for the PEOMG10 implant occurred at the interface between the coating and the bone side owing to its good interface status. The present study can expand the widespread applications of the titania-based hydroxyapatite composite materials for repairing hard tissues and teeth filling.

Sr-containing micro/nano-hierarchical textured TiO2 nanotubes on 3D printing titanium

The design of biomimetic structures on the surface of titanium implants is critical to improve cell response and bone integration. In this work, Sr-incorporated micro/nano hierarchical structures coatings were fabricated on 3D printing titanium by acid etching, anodization, and hydrothermal treatment. Various characterizations were used to investigate the morphology, hydrophilicity, corrosion resistance, crystal phase, and chemical composition of coatings. Furthermore, we also investigated their in-vitro mineralization capacity upon soaking in simulated body fluid. The obtained coatings show not only excellent corrosion resistance (−0.32 V), high adhesion strength (10.51 N), and hydrophilicity (7.6°), but also superior apatite induction ability. These results suggest that Sr-containing micro/nano-hierarchical textured coatings exhibit potential applications in orthopedic implant materials.

Fabrication of Sr-functionalized micro/nano-hierarchical structure ceramic coatings on 3D printing titanium

ABSTRACT Effective and fast osseointegration is significantly affected by the topographic features and chemical compositions of titanium (Ti)-based orthopedic implants. In this study, strontium (Sr) ions functionalized ceramic coatings with cortex-like micro/nano-hierarchical structure were successfully fabricated on 3D printing Ti by micro-arc oxidation and hydrothermal treatment technology. The obtained coatings, which combine micron-scale pores and nano-scale flakes simultaneously, show rough and porous morphology, good surface wettability, and superior apatite induction ability. Therefore, Sr-incorporated biomimetic hierarchical structure coatings on 3D printing Ti may provide an alternative for the development of orthopedic implants, showing high-potential clinical application.

Preparation, in vitro bioactivity and osteoblast cell response of Ca-Ta2O5 nanorods on tantalum

The novel Ca-Ta2O5 nanorods films were successfully prepared by two step hydrothermal synthesis. XRD (X-ray diffraction), SEM (scanning electron microscope), TEM (transmission electron microscopy), XPS (X-ray photoelectron spectroscopy) and AFM (atomic force microscopy) were used to analyze the phase and surface microstructure. ICP (inductively coupled plasma emission spectroscopy) was used to detect the ion precipitation concentration of the samples in normal saline, and the apatite induction ability was tested by simulated body fluid immersion experiment. Finally, the biological activity of the calcium-doped nanorods film was tested by cell experiment. The results showed that the Ta2O5 and Ca-Ta2O5 nanorods films were formed on tantalum and exhibited a nanorod structure growing along the [001] direction. The roughness and morphology of the nanorods had not been significantly affected by the doping of calcium. The Ca-Ta2O5 nanorods had good in vitro structural stability. Compared to Ta2O5 nanorods, the apatite induction ability of Ca-Ta2O5 nanorods film was significantly enhanced. Under the dual action of the nanorods structure and the element of Ca, the in vitro cell-culture studies clearly demonstrate that the Ca-Ta2O5 nanorod film was more suitable for the attachment and proliferation of MC3T3-E1 cells than the Ta substrate and Ta2O5 nanorod films. The Ta substrate/Ca-Ta2O5 nanorods film is expected to be a promising biomaterial for orthopedic applications for its high biocompatibility and bioactivity.

The hydrothermal treated Zn-incorporated titania based microarc oxidation coating: Surface characteristics, apatite-inducing ability and antibacterial ability

To improve the bioactivity and antibacterial ability of Zn-incorporated microarc oxidation (MAO-Zn) coating, the MAO-Zn coating was modified by hydrothermal treatment with deionized water (MAO-Zn-HT-0) and 5 mol/L NH3·H2O solution (MAO-Zn-HT-5). The hydrothermal treatment had a significantly effect on the structure, element and phase compositions of MAO-Zn coating. The hydrothermal treated MAO-Zn coatings remained the rough porous structure. Meanwhile, there were some TiO2 or CaTiO3 particles formed on the MAO-Zn-HT-0 and MAO-Zn-HT-5 coatings. Moreover, due to the dissolution of Ca and P elements and the enrichment of Zn element, the content of Zn element on the hydrothermal treated MAO-Zn coating surface was greatly increased. In addition, the Zn element existed in the amorphous ZnO after hydrothermal treatment. The release behavior of Zn element in the hydrothermal treated MAO-Zn coating exhibited slow, stable and continued. Compared to MAO-Zn coating, the MAO-Zn-HT-5 coating showed excellent apatite-inducing ability due to the formation of CaTiO3 and Ti-OH. Likewise, the antibacterial rates of the MAO-Zn-HT-0 coatings for E. coli and S. aureus were significantly improved due to the increase of Zn element on the MAO-Zn-HT-0 coating surfaces. Thus, the hydrothermal treatment was an effective method to improve the bioactivity and antibacterial ability of MAO-Zn coating.

Structural Characteristics and Bioactivity of Sr Doped Ta2O5 Nanorods on Tantalum by a Facile Two Step Hydrothermal Method

The Sr doped Ta2O5 nanorods films were formed on pure tantalum by a facile two step hydrothermal method. The tantalum substrates were hydrothermally treated firstly in the mixed solution of HF and H2O2 and then in strontium acetate (SA) solution. The morphologies, phase components, surface chemical species and apatite-inducing ability of the Ta2O5 nanorods films before and after Sr doped were investigated. The obtained results demonstrate that Ta2O5 nanorods can be only formed on tantalum at the temperature higher than 220 °C when hydrothermally treated in 0.4 M HF and 2 M H2O2. By prolonging the HT time to 6, 9 and 24 h, the nanorods become longer and the diameter become coarser, and after 24 h of HT, the diameter of the nanorod is 24.9 ± 0.9 nm. The atom percent of Sr element is 0.00, 1.61, 4.08, 7.71 and 11.23% respectively when Ta2O5 nanorods films were hydrothermally treated in SA solution of 0.01, 0.05, 0.1, 0.2 and 0.3 M, and Ta2O5 nanorods films changes in morphology when hydrothermally treated in 0.2 and 0.3 M SA solution though with high amount of Sr doped. The Ta2O5 nanorods are grown along the [001] direction and Sr element is incorporated into the lattice as the chemical state of Sr2+. The Sr doped Ta2O5 nanorods film can induce apatite for less than 9 days while that without Sr doped can not induce apatite even after immersion in SBF for 17 days. The Sr doped Ta2O5 nanorods film can efficiently improve the apatite-inducing ability in SBF which is maybe attributed to the release of Sr ion.

The effect of applied voltages on the structure, apatite-inducing ability and antibacterial ability of micro arc oxidation coating formed on titanium surface

The micro arc oxidation (MAO) coatings with different concentrations of Ca, P and Zn elements are successfully formed on the titanium substrate at the different applied voltages. After MAO treatment, the MAO coating exhibits the porous surface structure and composed of anatase and rutile TiO2 phases. Meanwhile, the average size and density of micro-pores on the MAO coatings have been modified via the adjusting the applied voltages. In addition, the contents of the incorporated elements such as Zn, Ca and P elements in the MAO coatings have been optimized. The bonding strength test results reveal that the MAO coating shows higher bonding strength, which is up to 45 ± 5 MPa. Compared to the pure Ti plate, the MAO coating formed at 350 and 400 V show good apatite-inducing ability. Meanwhile, the MAO coating containing Zn, Ca and P elements have better antibacterial ability for E.coli and S.aureus. Thus, the incorporation of Zn, Ca and P elements was an effective method to improve the antibacterial ability. Moreover, the concentrations of Zn, Ca and P elements could be adjusted with the changing of the applied voltages. As a result, the enhancement of the antibacterial ability on the MAO coating surfaces was depended on the comprehensive effect of the incorporated elements and the surface property of MAO coatings.

Electrophoretic deposition of chitosan–bioglass®–hydroxyapatite–halloysite nanotube composite coating

The composite coatings of chitosan (CS)–bioglass® (BG)–hydroxyapatite (HA)–halloysite nanotube (HNT) were investigated and produced via electrophoretic deposition (EPD) technique. The utilization of CS as a dispersing, blending and charging agent for ceramic particles, including BG, HA and HNT, allowed the formation of CS–BG/HA/HNT composite, functionally graded composite (FGC) and bilayer film containing different layers. The results of scanning electron microscopy (SEM), energy-dispersive spectrometry (EDS), X-ray diffraction (XRD) and Fourier transform infrared spectroscopy (FTIR) illustrate the composite in the form of the optimum distribution of ceramic components in the CS matrix with thickness of 28 µm on titanium (Ti) substrate. Electrochemical impedance spectroscopy (EIS) and potentiodynamic polarization tests indicate that the corrosion resistance of the coated sample increases in corrected simulated body fluid (C-SBF) at 37 °C. Finally, the apatite-inducing ability of CS–BG–HA–HNT is proved by the formation of carbonated hydroxyapatite particles on composite coating in C-SBF.

Enhanced corrosion resistance and in vitro bioactivity of NiTi alloys modified with hydroxyapatite-containing Al2O3 coatings

Hydroxyapatite (HA)-containing Al2O3 coatings were prepared on NiTi alloys through a cathodic plasma electrolytic deposition (CPED) process, followed by hydrothermal treatment (HT). The surface morphology, elemental distribution and phase composition of each coating were studied by scanning electron microscopy (SEM), energy-dispersive spectroscopy (EDS), and X-ray diffraction (XRD). SEM observations revealed that the coatings exhibited a “crater-like” porous structure, and that the thickness of the coating could be up to 100 μm. The results of EDS demonstrated that the Ca and P concentrations in the Al2O3 coatings could be increased to 8.2% and 4.7%, respectively, and that the Ca/P ratio could reach 1.72, which was close to that of natural HA. The results of XRD analysis showed that the CPED coating mainly comprised α-Al2O3 and γ-Al2O3, and that HA crystallization was induced by the subsequent HT. The corrosion resistance of the samples was investigated by potentiodynamic polarization tests and electrochemical impedance spectroscopy (EIS). The results showed that the corrosion resistance of the sample with the CPED-HT coating was enhanced by more than two orders of magnitude compared to that of the uncoated NiTi alloy. Ni ion release in simulated body fluid (SBF) was characterized by inductively coupled plasma-atomic emission spectroscopy, and the results showed a significant drop in the concentration of released Ni ions from 18.0 μg/mL for the uncoated NiTi alloy to 0.7 μg/mL for the CPED-HT coating. In addition, the SBF soaking test showed that HA precipitated on the CPED-HT coating and that the HA layer became thicker and larger with increasing soaking time, indicating that the CPED-HT coating exhibited excellent apatite-inducing ability. Thus, the introduced CPED-HT treatment provides a new and effective route for the surface modification of NiTi alloys for use as biomedical materials.

Preparation of Ca doping ZrO2 coating on NiTi shape memory alloy by cathodic plasma electrolytic deposition and its structure, in-vitro bioactivity and biocompatibility analysis

The Ca doping ZrO2 coatings were fabricated on NiTi alloys by cathodic plasma electrolytic deposition (CPED) technology. The CPED coatings exhibit a rough morphology filled with porous craters. The coating thickness is increased with the treatment time increasing. The X-ray diffraction (XRD) analysis shows that the coating is mainly composed of tetragonal phase ZrO2 (t-ZrO2). The X-ray photoelectron spectroscopy (XPS) indicates that the coating is composed by Zr, O, and Ca. The curves of potentiodynamic polarization suggest that the corrosion resistance of the NiTi alloy is significantly improved by the fabricated ZrO2 coating. Ni ions release test shows that CPED coating could mitigate the Ni ions release effectively. The SBF soaking test shows that the ZrO2 coatings exhibited excellent apatite-inducing ability, indicating the bioactivity of NiTi alloys is surely improved. The result of the osteoblast-like cells culture test shows that the adhesion, viability and proliferation of osteoblast-like cells on the ZrO2 coatings are enhanced. It indicated that the obtained ZrO2 coatings have good biocompatibility.

Effects of calcium salts on microstructure and corrosion behavior of micro-arc oxidation coatings on Mg-2Zn-1Ca-0.8 Mn alloy

Micro-arc oxidation (MAO) in an alkaline disodium hydrogen phosphate electrolyte containing different calcium salts has been used to produce oxide coatings on self-designed Mg-2Zn-1Ca-0.8 Mn alloy as a potential biodegradable bone implant material. SEM with EDS, XRD and FT-IR were used to characterize microstructures, elemental distribution and compositions of the MAO coatings. Potentiodynamic polarization curves and corrosion morphologies of the coating in the SBF solution are also presented. The results show that the coatings formed in (CH3COO)2Ca-containing electrolyte exhibit better apatite-inducing ability. However, the coatings formed in Ca(C6H11O7)2·H2O-containging electrolyte show lower corrosion resistance than those formed in (CH3COO)2Ca and (C6H5O7)2Ca3·4H2O containing electrolyte.

Effect of heat treatment atmosphere on the structure and apatite-inducing ability of Ca, P, Si and Na incorporated microarc oxidation coating on titanium

Amorphous microarc oxidation (MAO) coating containing Ca, P, Si and Na elements on Ti substrate has been heat treated in different atmospheres (air or argon) to adjust the phase composition, surface structure and bioactivity. After heat treatment in air at 800°C for 1h, the coating consists of anatase, rutile and CaTi4(PO4)6, with almost unchanged microporous surface structure. As for the one treated in argon at 800°C for 1h, anatase and rutile are formed on the coating, and the coating surface is covered by flower-like rutile particles. The formation of rutile particles could be attributed to the prior growth of the oxidized β-Ti along the discharge channel caused by the diffusion of incorporated elements. Thanks to the crystallization of TiO2 and the rise of surface roughness, which provides good sites for apatite nucleation, the MAO coated Ti after heat treatment in argon at 800°C exhibits good apatite-inducing ability.

Hierarchical Micropore/Nanorod Apatite Hybrids In-Situ Grown from 3-D Printed Macroporous Ti6Al4V Implants with Improved Bioactivity and Osseointegration

The advent of three-dimensional (3-D) printed technique provides great possibility in the fabrication of customized porous titanium (Ti) implant. However, the bioinert property of the printed Ti poses an outstanding problem. Hybrid micro-arc oxidation and hydrothermal (MAO–HT) treatment on porous metals is able to produce multi-scaled hierarchical orthopedic implant, showing great potential for surface modification of 3-D printed implant. In this study, cylindrical porous Ti6Al4V (Ti64) scaffolds with pore size of 640 µm, porosity of 73% were 3-D printed by electron beam melting process, and their surfaces were left untreated or treated by a combined MAO–HT procedure. In vitro bioactivity was tested by immersion in simulated body fluid for different time points. Then, 12 scaffolds in each group were implanted into the femoral condyles of New Zealand rabbit for 8 weeks. Osseointegration was evaluated by qualitative and quantitative histological analysis, and the bone ingrowth features were probed by sequential fluorescent labeling at 3 and 6 weeks post-surgery. Following the MAO–HT treatment, the porous Ti64 scaffold was endowed with multi-scaled micro/nano-topographies and high amounts of CaP on its surface. The treated scaffold exhibited drastically enhanced apatite forming ability compared with the untreated one. In vivo test revealed significantly that a higher amount of bone ingrowth and bone implant contact at the treated scaffold. The 2 types of scaffolds had different patterns of bone ingrowth: the treated scaffold exhibited a pattern of contact osteogenesis, by which bone formed directly on the treated implant surface, whereas bone formed distal to the implant surface of the untreated scaffold. MAO–HT treatment can significantly enhance the in vitro apatite-inducing ability and in vivo osseointegration capacity of 3-D porous Ti64 scaffold and may provide as a viable approach for the fabrication of bioactive 3-D printed porous implant for orthopedic applications.

Bioactive surface modification of Ti–29Nb–13Ta–4.6Zr alloy through alkali solution treatments

Bioactive surface modification of Ti–29Nb–13Ta–4.6Zr alloy (TNTZ) was performed through three different alkali solution treatments, including the electrochemical (E), hydrothermal (H), and hydrothermal-electrochemical (HE) processes; all of the processes lead to the formation of sodium-contained amorphous titanium oxide layers on TNTZ samples. The TNTZ samples subjected to the E, H, and HE processes exhibit a flat surface, smooth and fine mesh-like structure surface, and rough mesh-like structure surface, respectively. In the bioactive test, namely, simulated body fluid test, apatite inductivity increases as the surface morphology becomes rough. The order of inductivity for the three processes was HE>H>E. The surface chemical composition also affects the apatite induction ability. The surface with fewer niobium species exhibits better apatite inductivity.

Preparation and characterization of TiO2/silicate hierarchical coating on titanium surface for biomedical applications

In the current work, TiO2/silicate hierarchical coatings with various nanostructure morphologies were successfully prepared on titanium substrates through micro-arc oxidation (MAO) and subsequent hydrothermal treatment (HT). Moreover, the nucleation mechanism and growth behavior of the nanostructures, hydrophilicity, protein adsorption and apatite-inducing ability of various coatings were also explored. The novel TiO2/silicate hierarchical coatings comprised calcium silicate hydrate (CSH) as an outer-layer and TiO2 matrix as an inner-layer. According to the morphological features, the nanostructures were classified as nanorod, nanoplate and nanoleaf. The morphology, degree of crystallinity and crystalline phases of CSH nanostructures could be controlled by optimizing the HT conditions. The nucleation of CSH nanostructures is caused by release and re-precipitation mechanism. The TiO2/CSH hierarchical coatings exhibited some enhanced physical and biological performances compared to MAO-fabricated coating. The improvement of the hydrophilicity, fibronectin adsorption and apatite-inducing ability was found to be morphological dependent according to the following trend: nanoleaf coating>nanoplate coating>nanorod coating>MAO coating. The results indicate that the tuning of physical and morphological properties of nanostructures coated on biomaterial surface could significantly influence the hydrophilicity, protein adsorption and in vitro bioactivity of biomaterial.

The structure, bond strength and apatite-inducing ability of micro-arc oxidized tantalum and their response to annealing

In this study, the tantalum oxide coatings were formed on pure tantalum (Ta) by micro-arc oxidation (MAO) in electrolytic solutions of calcium acetate and β-glycerophosphate disodium, and the effect of the applied voltage on the microstructure and bond strength of the MAO coatings was systematically investigated. The effect of annealing treatment on the microstructure, bond strength and apatite-inducing ability of the MAO coatings formed at 350 and 450V was also studied. The study revealed that during the preparation of tantalum oxide coatings on Ta substrate by MAO, the applied voltage considerably affected the phase components, morphologies and bond strength of the coatings, but had little effect on surface chemical species. After annealing treatment, newly formed CaTa4O11 phase mainly contributed to the much more stronger apatite-inducing ability of the annealed tantalum oxide coatings than those that were not annealed. The better apatite-inducing ability of the MAO coatings formed at 450V compared to those formed at 350V was attributed to the less amorphous phase and more crystalline phase as well as more Ca and P contained in the MAO coatings with increasing the applied voltage.