Treated Titanium Substrates Research Articles

Promoting osteoblast proliferation and differentiation on functionalized and laser treated titanium substrate using hydroxyapatite/β-tricalcium phosphate/silver nanoparticles

In the present study, a novel composite coating consisting of nano-silver (nAg) with an association of hydroxyapatite (HA)- β-tricalcium phosphate (β-TCP) particles was developed by surface coating onto Ti substrate through two different but aligned steps: first nAg-HP (containing a different ratio of HA and β-TCP particles) composite was coated by sol-gel technique with the association of poly (vinyl alcohol) (PVA) as a binding agent to the substrate, then continuous CO2 laser treatment was carried out to improve the surface properties. The physicochemical properties of fabricated coatings were evaluated by using X-ray diffractometry (XRD), and field emission scanning electron microscopy (FESEM) equipped with energy dispersive X-ray detector (EDX). The biological properties of composite coatings were observed by bioactivity measurement, antibacterial performance, MTT assay, and real-time PCR. The FESEM images and cross-section micrographs showed that the particles were distributed homogenously, and the interface was well-integrated. Mineralization assessment revealed treated surface was a better place for apatite nucleation and growth. The antibacterial measurement showed Ag nanoparticles enhanced significantly antibacterial activity reached up about 90%. The mRNA expression level for COL1A1, ALP, RUNX2, OCT, and GAPDH revealed the positive effect of functionalized and treated Ti substrate on osteoblast cell differentiation. The composite coating illustrated enhanced biological properties suggesting it is a promising candidate for further studies for practical biomedical applications.

Assessment of synergistic effects of LP-MOCVD TiO2 and Ti surface finish for dental implant purposes

Three differently treated titanium substrates to be used in dental implant applications and with different surficial morphology were coated with titanium dioxide (TiO 2 ) films by using Low-Pressure Metal Organic Chemical Vapor Deposition (MOCVD). No literature references were found on the performance evaluation of the TiO 2 MOCVD coatings on substrates with different pristine morphology; in this work the influence of the pristine Ti surface characteristics on TiO 2 crystalline structure, morphology, wettability as well as on ion release, electrochemical behavior, tribocorrosion performance, and nano-mechanical properties were studied and discussed. It was shown that the pristine substrate influenced both the crystalline phases' formation and crystallite size. Scanning electron microscopy analyses and roughness evaluation showed the optimal conformal coverage of all the MOCVD coatings for all substrates, with grain size depending on the substrate morphology and topography. The wettability of the TiO 2 coated Ti substrates highlighted a superhydrophilic behavior and, if stored in air, decreased as a function of the time aging. Ions release tests, nanoindentation measurements, tribocorrosion, and potentiodynamic polarization experiments suggest the enhancement of functional properties of the coated samples. Titania sandblasted/acid etched coated Ti substrates generally showed the best performance of the functional properties for their use in dental implant fabrications. • TiO 2 coated samples allow better wettability in aqueous media. • Titania surface functionalization is a good strategy to reduce ion release. • Tribocorrosion studies indicate better behavior for TiO 2 coated samples. • TiO 2 surface functionalization improves the mechanical properties of bulk titanium.

Enhanced adhesive strength between SU-8 photoresist and titanium substrate by an improved anodic oxidation method for high aspect-ratio microstructures

This paper presents an anodic oxidation treatment method for improving the adhesive strength between SU-8 photoresist and titanium substrate. The adhesion strengths were measured for the treated titanium substrates by different anodic oxidation techniques, which increased with the enhancement of the surface roughness and thorny structures on the treated substrate. It was found that the adhesion was increased by approximately 86% through anodic oxidation treatment in 3.0 mol l−1 NaOH solution compared to Si wafer substrate. Additionally, the influence of UV dosage and hard bake temperature on the adhesion strength was examined for the anodic oxidation treated substrates. The UV dosage effect, with a range from 0.8 to 2.08 J cm−2, was measured and analyzed for a 300 µm thickness SU-8 cylinder, and the adhesion strength corresponding to the optimal dosage (1.52 J cm−2) was 45.82 ± 3.08 MPa. The adhesion was further strengthened by a hard bake at 110 °C for 60 min and its value was up to 71.64 MPa, which almost approaches the breaking strength of the SU-8 polymer. Using the optimized anodic oxidation and UV lithography conditions, high aspect ratio (24) SU-8 micropillar arrays with 600 µm height were fabricated without any distortion, collapse or delamination. Finally, to evaluate the feasibility of the anodic oxidation treated titanium substrate to serve as a seed layer, the electrochemical properties were measured by polarization curves.

Anodic Growth and Characterization of Highly Nitrogen Doped Titanium Dioxide Nanotubes with Ordered Structure on Hot Argon DC Plasma Treated Titanium Substrates

Nitrogen-doped titanium dioxide (N-TiO2) nanotubes were grown via electrochemical anodization on hot argon DC plasma pre-treated titanium substrates. The anodization process was performed in ethylene glycol based electrolyte solution containing NH4F and deionized water at constant potential at room temperature. N-TiO2 nanotubes were synthesized during their electrochemical formation. It was observed that plasma pre-treatment decreased the surface roughness of titanium substrates. The anodic N-TiO2 nanotubes grown on plasma treated titanium substrates were longer with more ordered periodic structure with hexagonal cross-sectional morphology comparing to the anodic N-TiO2 nanotubes grown on non-plasma treated (reference) titanium substrate. EDX analysis revealed that the N-TiO2 nanotubes were grown during the anodization process with in situ chemical doping. Optical measurements revealed that the anodic N-TiO2 nanotubes grown on plasma treated titanium substrates had slightly lower band gap energy (2.35 eV) compared to the N-TiO2 nanotubes grown on non-plasma treated titanium substrate (2.4 eV).

Sand-blasting treatment as a way to improve the adhesion strength of hydroxyapatite coating on titanium implant

In the current study, the effect of corundum particle sizes (50 and 250–320 μm) used for sand–blasting on the structure, roughness, wettability, mechanical properties, and adhesion of radio frequency magnetron hydroxyapatite coating deposited on treated titanium substrate is studied. Morphology analysis revealed that pretreatment uniformly deforms the surface and induces the formation of pits, which size depends linearly on the grit size. The deposited coatings (Ca/P was in a range of 1.75-1.79) are homogeneous and repeat the relief of the substrate (mean roughness Ra is 1.9±0.1 (250–320 μm) and 0.8±0.1 μm (50 μm)). Texture coefficient calculations revealed the predominant (002) growth texture of hydroxyapatite coatings. The resistance of the coating to plastic deformation and the surface hardening were significantly higher for coatings formed on sand blasted with particle size of 50 μm. Scratch test have shown the significant improvement of wear resistance and lower friction coefficient of coatings for smoother samples. Dynamic contact angle measurements revealed the hydrophilic properties of the hydroxyapatite coating. Thus, sand–blasting of titanium with corundum powder having the size of 50 μm prior to the deposition of RF magnetron coating is recommended for the medical applications intended to improve the bonding between the substrate and coating.

Preparation of layered bioceramic hydroxyapatite/sodium titanate coatings on titanium substrates using a hybrid technique of alkali-heat treatment and electrochemical deposition

Bioceramic hydroxyapatite/sodium titanate coating on sandblasted titanium substrate was fabricated by a three-step process. At first, the sandblasted titanium substrate was coated with a flake-like sodium titanate layer by alkali-heat treatment. In the second step, the alkali-heat treated titanium substrate was hydrothermal treated at 180 °C for 4 h with calcium solutions. In the third step, the hydroxyapatite (HA) coating was deposited onto the hydrothermal treated layer via electrochemical deposition method. The surface topography and roughness of the coatings were determined by field emission scanning electron microscope (FESEM) and a mechanical contact profilometer, respectively. The surface compositions were evaluated by X-ray diffraction (XRD), energy-dispersive X-ray spectrum (EDS), and X-ray photoelectron spectroscopy (XPS). The EDS, XPS, and XRD analysis confirm the presence of element Ca, Ca2+, and CaTiO3 on sodium titanate layer after hydrothermal treatment with Ca(NO3)2 solution, respectively. FESEM micrograph shows the rod/needle-shaped crystallites are highly densely packed on the calcium-ion-containing layer with an average size of ~50 nm in diameter. The results indicate that the sodium titanate layer containing Ca2+ ions possesses higher ability to induce HA formation compared with the pure sodium titanate layer. It is revealed that surface composition plays an important role in the electrochemical deposition of HA. The calcium-ion-containing layer probably makes the nucleation of HA easy and effectively promotes orientated growth of HA on flake-like sodium titanate surface. The sodium titanate layer possesses a lower corrosion current density and a higher corrosion potential than sandblasted-Ti substrate. The sodium titanate layer should act as a barrier to the release of metal ions from metallic substrate to physiological solutions and thus reducing the electrochemical reaction rate.

Field Emission of Aluminum Nitride Nanocones Deposited on Titanium Substrate

We report the preparation of quasi-arrays of aluminum nitride nanocones via chemical vapor deposition on nitriding treated titanium substrate at 800 °C through the reaction between AlCl3 vapor and NH3/N2 gas. The field emission measurement exhibits a fine electron emission with the turn-on field of 10.7 V/mm, which is quite smaller than the turn-on field of 41.3 V/μm for aluminum nitride nanocones deposited on silicon wafer in our previous works. The reduction of turn-on field is attributed to the formation of a layer of conductive tiannium nitride on titanium substrate during the nitriding treatment.

Surface engineering of titanium with potassium hydroxide and its effects on the growth behavior of mesenchymal stem cells

To improve the corrosion resistance and biological performance of commercially pure titanium (cp-Ti) substrates, potassium hydroxide was employed to modify the surfaces of titanium substrates, followed by biomimetic deposition of apatite on the substrates in a simulated body fluid. The morphologies of native and treated titanium substrates were characterized by field emission scanning electron microscopy (FE-SEM). Treatment with potassium hydroxide led to the formation of intermediate layers of potassium titanate on the surfaces of titanium substrates, while apatite was subsequently deposited onto the intermediate layer. The formation of potassium titanate and apatite was confirmed by thin-film X-ray diffraction and FE-SEM equipped with energy dispersive spectroscopy, respectively. Electrochemical impedance spectroscopy showed that the formed potassium titanate layer improved the corrosion-resistance properties of titanium substrates. The influence of modified titanium substrates on the biological behavior of mesenchymal stem cells (MSCs), including osteogenic differentiation, was investigated in vitro. Compared with cp-Ti substrates, MSCs cultured onto alkali- and heat-treated titanium substrates and apatite-deposited titanium substrates displayed significantly higher ( P < 0.05 or P < 0.01) proliferation and differentiation levels of alkaline phosphatase and osteocalcin in 7 and 14 day cultures, respectively. More importantly, our results suggest that the modified titanium substrates have great potential for inducing MSCs to differentiate into osteoblasts. The approach presented here may be exploited to fabricate titanium-based implants.

Morphological and chemical characterisation of biomimetic bone like apatite formation on alkali treated Ti6Al4V titanium alloy

The present study is an attempt to enhance the apatite-forming ability of titanium metal induced by the alkaline (NaOH) treatment. A cell free culture medium, acellular DMEM solution was utilised to develop bone-like apatite on alkali-treated titanium alloy surface. The main advantage of this process is the development of bone like apatite with essential trace elements on the metallic substrate by using the DMEM culture medium as a soaking medium. The formed apatite deposits were investigated by scanning electron microscopy (SEM), energy dispersive X-ray spectroscopy (EDXS). The obtained results suggest that the method utilized in this work can be successfully applied to obtain deposition of uniform coatings of crystalline hydroxyapatite on alkali treated titanium substrates.

Improvement of Anselme's adhesion model for evaluating human osteoblast response to peptide-grafted titanium surfaces

Investigations on the relationships between the properties of biomaterial surfaces and cell adhesion/proliferation processes have recently gained increasing interest. To describe the behaviour of cells adhering and proliferating over different types of (and/or differently treated) substrates, some mathematical models have been also suggested in literature; these models consider both the dependence of cell adhesion/proliferation over time, and the influence of substrate morphology in allowing (or even hampering) cell attachment. Major developments in the biochemical functionalization of the materials used for the production of endosseous devices have been achieved; the ability of the so-called “biomimetic” surfaces to promote cell adhesion, thus favoring the osseointegration process, is already well acknowledged. The aim of this study was to formulate a mathematical model for osteoblast adhesion, mediated by an adhesion peptide (sequence 351–359 mapped on the Human Vitronectin Protein) covalently grafted to a titanium-based surface. To assure a highly homogenous orientation of the peptide to cells, the “specific functionalization” strategy was properly designed. Enzymatic detachment assays allowed comparing osteoblast behaviour over three differently treated titanium substrates (i.e., oxidized, silanized, and peptide-grafted), thus determining how and how much the bioactive peptide can improve the strength of cell adhesion. The results confirmed the capacity of the peptide to increase cell adhesion and adhesion strength; moreover, the role of the peptide was described by a mathematical equation characterizing cells behaviour.