Surface characteristics of Ti‐10Ta‐10Nb alloy modified by hydrogen peroxide treatment for dental implants

The use of titanium‐based alloys as biomaterials is becoming more common because they have a reduced elastic modulus, superior biocompatibility, specific strength, good corrosion resistance, superior strain control, and fatigue resistance compared to conventional stainless steel and Co? Cr alloys. However, when implanted into the human body these metals are problematic because they do not directly bond with living bone. Surface treatments play an important role in nucleating calcium phosphate deposition on a surgical titanium alloy implant. The purpose of this study is to examine whether the precipitation of apatite on Ti? 10Ta? 10Nb alloy is affected by surface modification in H₂O₂ solution. Specimens were chemically treated with a solution containing 30 wt% H₂O₂ at 80 °C for 1 h, and subsequently heat treated at 400 °C for 1 h. All specimens were immersed in SBF (Simulated Body Fluid) with a pH of 7.4 at 36.5 °C for seven days, and the surfaces were examined with XRD, SEM, EDX and in vitro testing. The microstructure analysis of the Ti? 10Ta? 10Nb alloy after etching with Keller's etchant showed a Widmanstatten pattern. The micro‐Vickers hardness number was 236.44 ± 4.99, and surface roughness was increased by the surface treatment. The wettability after surface treatment was better than on the nontreated surface. Resistance to cytotoxicity was decreased by the chemical surface treatment (P < 0.05). Copyright © 2011 John Wiley & Sons, Ltd.     

Characterization and corrosion properties of Ti‐O/HA composite coatings on Mg‐Zn alloy

Biodegradable magnesium alloys have been widely investigated in the field of biomaterials because they can be gradually dissolved and absorbed by the human body without long‐term existence. However, it was found that bare magnesium implants suffered from rapid corrosion. Surface modification is applied to improve the corrosion resistance and biocompatibility of magnesium implants. In this study, Ti‐O/HA composite coatings including typical flakes and nanofibers were fabricated on the Mg‐Zn alloy. The Ti‐O films were deposited on the magnesium alloy by direct current magnetron sputtering, and subsequently coated with HA flakes and nanofibers by electrochemical deposition, respectively. The obtained coatings were investigated by X‐ray diffraction, Fourier Transform Infrared spectroscopy and scanning electron microscopy. The corrosion resistance was evaluated by potentiodynamic polarization and hydrogen evolution tests in simulated body fluid at 37 °C. The results show that the compact Ti‐O films are composed of particles within the size of 100 nm, the outermost HA coatings are predominantly composed of HA and doped with Na⁺, Mg²⁺ ions and functional groups. The stronger diffraction and broader peak in nanofibers than typical flakes around 25.8° are ascribed to the preferential growth in orientation (002). The morphology of HA coatings changed from typical flakes into nanofibers with the addition of NaF, the mechanism to explain the difference is also discussed. The corrosion resistance was improved significantly by the coatings, the corrosion rates in the 10 days were 4.13, 1.77, 0.96 and 0.85 mm/y, respectively. Copyright © 2011 John Wiley & Sons, Ltd.     

Hydrophilic dual‐responsive magnetite/PMAA core/shell microspheres with high magnetic susceptibility and ph sensitivity via distillation‐precipitation polymerization

A facile and effective approach to preparation of dual‐responsive magnetic core/shell composite microspheres is reported. The magnetite(Fe₃O₄)/poly(methacrylic acid) (PMAA) composite microspheres were synthesized through encapsulating γ‐methacryloxypropyltrimethoxysilane (MPS)‐modified magnetite colloid nanocrystal clusters (MCNCs) with crosslinked PMAA shell. First, the 200‐nm‐sized MCNCs were fabricated through solvothermal reaction, and then the MCNCs were modified with MPS to form active vinyl groups on the surface of MCNCs, and finally, a pH‐responsive shell of PMAA was coated onto the surface of MCNCs by distillation‐precipitation polymerization. The transmission electron microscopy (TEM) and vibrating sample magnetometer characterization showed that the obtained composite microspheres had well‐defined core/shell structure and high saturation magnetization value (35 emu/g). The experimental results indicated that the thickness and degree of crosslinking of PMAA shell could be well‐controlled. The pH‐induced change in size exhibited by the core/shell microspheres reflected the PMAA shell contained large amount of carboxyl groups. The carboxyl groups and high saturation magnetization make these microspheres have a great potential in biomolecule separation and drug carriers. Moreover, we also demonstrated that other magnetic polymeric microspheres, such as Fe₃O₄/PAA, Fe₃O₄/PAM, and Fe₃O₄/PNIPAM, could be synthesized by this approach. © 2011 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem, 2011.     

Catalytic Au Electrodes Based on SAMs of per(6‐deoxy‐6‐thio‐2,3‐di‐O‐methyl)‐β‐cyclodextrin

A three‐step sequential self‐assembly procedure was applied in preparing gold electrodes modified in a stable and controlled way by a monolayer of thiolated β‐cyclodextrin (β‐CD), with methylene blue (MB) included in its cavity as the active component of the monolayer, and octanethiol as the nonelectroactive spacer blocking the electrode surface not occupied by β‐CD. MB acted as a mediator of electrons with respect to a solution soluble analyte, H₂O₂, and provided electrical contact between the electrode and solution resident enzyme, laccase, catalyzing reduction of oxygen to water.     

Functionalization of graphene oxide towards thermo‐sensitive nanocomposites via moderate in situ SET‐LRP

A mild and efficient strategy is presented for growing thermo‐sensitive polymers directly from the surface of exfoliated graphene oxide (GO). This method involves the covalent attachment of Br‐containing initiating groups onto the surface of GO sheets followed by in situ growing poly[poly(ethylene glycol) ethyl ether methacrylate] (PPEGEEMA) via single‐electron‐transfer living radical polymerization (SET‐LRP). Considering the lack of reactive functional groups on the surface of GO, exfoliated GO sheets were subjected to an epoxide ring opening reaction with tris(hydroxymethyl) aminomethane (TRIS) at room temperature. The initiating groups were grafted onto TRIS‐GO sheets by treating hydroxyls with 2‐bromo‐2‐methylpropionyl bromide at room temperature. PPEGEEMA chains were synthesized by in situ SET‐LRP using CuBr/Me₆TREN as catalytic system at 40 °C in H₂O/THF. The resulting materials were characterized using a range of testing techniques and it was proved that polymer chains were successfully introduced to the surface of GO sheets. After grafting with PPEGEEMA, the modified GO sheets still maintained the separated single layers and the dispersibility was significantly improved. This TRIS‐GO‐PPEGEEMA hybrid material shows reversible self‐assembly and deassembly in water by switching temperature at about 34 °C. Such smart graphene‐based materials promise important potential applications in thermally responsive nanodevices and microfluidic switches. © 2011 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem, 2011     

Synthesis,characterization and catalytic performance of core‐shell structure magnetic Fe3O4/P(GMA‐EGDMA)‐NH2/HPG‐COOH‐Pd catalyst

A strategy has been developed for the synthesis, characterization and catalysis of magnetic Fe₃O₄/P(GMA‐EGDMA)‐NH₂/HPG‐COOH‐Pd core‐shell structure supported catalyst. The P(GMA‐EGDMA) polymer layer was coated on the surface of hollow magnetic Fe₃O₄ microspheres through the effect of KH570. The core‐shell magnetic Fe₃O₄/P(GMA‐EGDMA) modified by ‐NH₂ could be grafted with HPG. Then, the hyperbranched glycidyl (HPG) with terminal ‐OH were modified by ‐COOH and adsorbed Pd nanoparticles. The hyperbranched polymer layer not only protected the Fe₃O₄ magnetic core from acid–base substrate corrosion, but also provided a number of functional groups as binding sites for Pd nanoparticles. The prepared catalyst was characterized by UV–vis, TEM, SEM, FTIR, TGA, ICP‐OES, BET, XRD, DLS and VSM. The catalytic tests showed that the magnetic Fe₃O₄/P(GMA‐EGDMA)‐NH₂/HPG‐COOH‐Pd catalyst had excellent catalytic performance and retained 86% catalytic efficiency after 8 consecutive cycles.     

Corrosion,wear, and cell culture studies of oxygen ion implanted Ni–Ti alloy

To increase the biocompatibility of nickel–titanium (Ni–Ti) alloy substrates, oxygen ions have been implanted by the plasma immersion ion implantation (PIII–O) technique at low temperature without affecting the substrate properties. The implanted Ni–Ti surface is characterized for microhardness and composition. Energy‐dispersive spectroscopy and X‐ray photoelectron spectroscopy investigations show the replacement of native oxide on the alloy by a compact oxide during the implantation process. The corrosion behaviors of untreated substrate and PIII–O samples are investigated using potentiodynamic polarization and electrochemical impedance spectroscopy in simulated body fluid (Hanks' solution). Polarization and electrochemical impedance spectroscopy studies reveal nearly ideal capacitor behavior with better passivation characteristics for the oxygen‐implanted substrate. Sliding wear studies reveal lower friction of coefficient for the implanted layers as compared with the substrate. The bare and surface modified Ni–Ti alloy samples are evaluated for biocompatibility using osteoblast‐like cells (MG‐63). Cellular behavior in terms of cell morphology along with the viability and proliferations is evaluated by using scanning electron microscopy and in vitro cell culture assay, respectively. The results clearly show that oxygen implantation by PIII–O provides a better compatible surface for cell attachment and growth. The modified surface exhibits a higher percentage of cell viability demonstrating the enhanced biocompatibility of the oxygen‐implanted surface compared with bare Ni–Ti alloy. Copyright © 2017 John Wiley & Sons, Ltd.     

Preparation and characterization of novel PES‐(SiO2‐g‐PMAA) membranes with antifouling and hydrophilic properties for separation of oil‐in‐water emulsions

In the present study, modification of nanoparticles (NPs) was investigated to mitigate aggregation of SiO₂ nanoparticles and improve the polymeric membrane's performance. For this purpose, the surface of SiO₂ nanoparticles was activated with amine groups, and polymethacrylic acid (PMAA) was grafted on the surface of NPs by atom transfer radical polymerization. Modified NPs were characterized by Fourier transform infrared spectroscopy (FTIR) and thermogravimetric analysis (TGA) tests. Polyethersulfone (PES) membranes were fabricated with both SiO₂ and SiO₂‐g‐PMAA NPs via nonsolvent‐induced phase separation method. The fabricated membranes were characterized regarding their permeability, hydrophilicity, and porosity properties, and their separation efficiency was tested using the synthetic oil‐in‐water emulsion. The surface and cross‐sectional morphologies of membranes were observed by field emission scanning electron microscopy (FESEM). The experimental trials showed that modified NPs dispersed more uniformly in the structure of membranes and hydroxyl groups on the surface of NPs acted more effectively. Modification of NPs enhance the membrane performance in terms of permeate flux, hydrophilicity, and porosity. NPs modification improved the permeate flux about 46%. Oil rejection for all tested membranes was more than 98%, and modification of NPs did not reduce the rejection of membranes. The optimum concentration was obtained as 1 wt.% and 1.5 wt.% for SiO₂ and SiO₂‐g‐PMAA, respectively. Aggregation effect dominated at concentrations beyond the optimum values that decreased the permeate flux, consequently.     

Metal Organic Polyhedra: A Click‐and‐Clack Approach Toward Targeted Delivery

Mixed self‐assembly of ligands 1 and 2 , PXDA ( 3 ), and Pd(NO₃)₂ afforded metal organic polyhedra ( MOP 1  –  MOP 3 ) which bear 24 covalently attached CB[7] and cyclooctyne moieties. Post assembly modification (PAM) of MOP 3 by covalent strain promoted alkyne azide click reaction provided MOP 4 ^R bearing covalently attached functionality (PEG, sulfonate, biotin, c‐RGD, fluorescein, and cyanine). Orthogonal CB[7]·guest mediated non‐covalent PAM of MOP 4 ^R with Ad‐ FITC afforded MOP 5 ^RGD • Ad‐ FITC and MOP 5 ^biotin • Ad‐ FITC . Flow cytometry analysis of the uptake of MOP 5 ^RGD • Ad‐ FITC toward U87 cells demonstrated improved uptake relative to control MOP lacking c‐RGD ligands. These results suggest a broad applicability of orthogonally functionalizable (covalent and non‐covalent) MOPs in targeted drug delivery and imaging applications.     

Water adsorption on the surface of Ni‐ and Co‐based layer‐structured cathode materials for lithium‐ion batteries

Ni‐based layer‐structured cathode materials are more vulnerable to moisture than conventional LiCoO₂ cathodes, adsorbing more water and easily forming LiOH on the surface. This study investigated the moisture adsorption mechanism on the surface of layer‐structured cathodes. The behavior of water molecules on LiCoO₂ and LiNiO₂ surfaces were simulated and the structural and chemical changes during the adsorption process were analyzed by first‐principles methods. It was found that the adsorption occurs via two types of mechanism: one involving ionic interactions between Li on the crystal surface and O in the adsorbate, and the other involving covalent bonding between the transition metal (TM) on the surface and O in the adsorbate, which restores the coordination of the TM by recovering its broken bonds. The difference between the water adsorption behaviors of Ni‐based and Co‐based layer‐structured cathodes was found to be mainly due to the ionic‐interaction‐driven adsorption on the (003) surface.     

Single‐Walled Carbon Nanotubes Modified Gold Electrodes as an Impedimetric DNA Sensor

A gold surface modified with a self‐assembled monolayer of 11‐amino‐1‐undecanethiol (AUT) was used for the covalent immobilization of oxidized single‐walled carbon nanotubes (SWNTs). The as‐described SWNTs‐modified substrate was subsequently used to attach single‐stranded deoxyribonucleic acid (ssDNA) used as a substrate for DNA hybridization. Electrochemical impedance spectroscopy measurements were performed to follow the DNA hybridization process by using the redox couple [Fe(CN)₆]^3−/4− as a marker ion. Specifically, changes in charge transfer resistance obtained from the Nyquist plots were used as the sensing parameter of DNA hybridization. The substrate sensitivity towards changes in target DNA concentration, its selectivity toward different DNA sequences and its reusability are successfully demonstrated in this report.     

The Signal‐Enhanced Label‐Free Immunosensor Based on Assembly of Prussian Blue‐SiO2 Nanocomposite for Amperometric Measurement of Neuron‐Specific Enolase

A signal‐enhanced label‐free electrochemical immunosensor was constructed by the employment of Prussian blue doped silica dioxide (PB‐SiO₂) nanocomposite. At first, PB‐SiO₂ nanocomposite which was produced by using a microemulsion method was used to obtain a nanostructural monolayer on a glassy carbon electrode (GCE) surface. Next amino‐functionalized interface were prepared by self‐assembling 3‐aminopropyltriethoxy silane (APTES) on the PB‐SiO₂ nanoparticle surface. Then chitosan stabled gold nanoparticle (CS‐nanoAu) was subsequently attached, while the entire surface was finally loaded with neuron‐specific enolase antibody (anti‐NSE) via the adsorption of gold nanoparticle. The sensitivity of the proposed immunosensor has greatly improved as the PB‐SiO₂ nanostructural sensing film provides plenty of active sites which might catalyze the reduction of H₂O₂. The immunosensor exhibited good linear behavior in the concentration range from 0.25–5.0 and 5.0–75 ng/mL for the quantitative analysis of neuron‐specific enolase (NSE), a putative serum marker of small‐cell lung carcinoma (SCLC), with a limit of detection of 0.08 ng/mL. The resulting NSE immunosensor showed high sensitivity and long‐term lifetime which can be attributed to the extremely high catalytic activity and biocompatibility of CS‐nanoAu/APTES/PB‐SiO₂ nanostructural multilayers.     

Covalent polymeric modification of graphene nanosheets via surface‐initiated single‐electron‐transfer living radical polymerization

Graphene nanosheets offer intriguing electronic, thermal, and mechanical properties and are expected to find a variety of applications in high‐performance nanocomposite materials. Dispersal of graphene nanosheets in polymer hosts and precise interface control are challenging due to their strong interlayer cohesive energy and surface inertia. Here, an efficient strategy is presented for growing polymers directly from the surface of reduced graphene oxide (GO). This method involves the covalent attachment of Br‐containing initiating groups onto the surface of hydrazine hydrate reduced GO via a diazonium addition and the succeeding linking of poly(tert‐butyl methacrylate) (PtBMA) chains (71.7 wt % grafting efficiency) via surface‐initiated single‐electron‐transfer living radical polymerization (SET‐LRP) to graphene nanosheets. The resulting materials were characterized by using a range of testing techniques and it was proved that polymer chains were successfully introduced to the surface of exfoliated graphene sheets. After grafting with PtBMA, the modified graphene sheets still maintained the separated single layers, and the dispersibility was improved significantly. The method is believed to offer possibilities for optimizing the processing properties and interface structure of graphene–polymer nanocomposites. © 2011 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem, 2011.     

Facile Fabrication of Solid‐state Electrochemiluminescence Sensor via Non‐covalent π‐π Stacking and Covalent Bonding on Graphite Electrode

Herein, a facile and efficient method was developed for fabrication of solid‐state electrochemiluminescence (ECL) sensor via non‐covalent π‐π stacking and covalent bonding on the graphite electrode (GE) surface. The electrode was firstly modified with 1‐aminopyrene via π‐π stacking between GE surface and the pyrene moiety. Thereafter a stable and efficient solid‐state ECL sensor was fabricated by covalent immobilization of ruthenium(II) onto the GE surface via amidation reaction between the 1‐aminopyrene and bis(2,2′‐bipyridyl)(4‐methyl‐4′‐carboxypropyl‐2,2′‐bipyridyl) ruthenium(II) bishexafluorophosphate. The sensor has been investigated using tripropylamine and tetracycline as representative analytes, and low detection limits of 0.7 nM and 3.5 nM (S/N=3) were reached, respectively.     

The Modification of Screen‐Printed Carbon Electrodes with Amino Group and Its Application to Construct a H2O2 Biosensor

Electrooxidation of thionine on screen‐printed carbon electrode gives rise to the modification of the surface with amino groups for the covalent immobilization of enzymes such as horseradish peroxidase (HRP). The biosensor was constructed using multilayer enzymes which covalently immobilized onto the surface of amino groups modified screen‐printed carbon electrode using glutaraldehyde as a bifunctional reagent. The multilayer assemble of HRP has been characterized with the cyclic voltammetry and the faradaic impedance spectroscopy. The H₂O₂ biosensor exhibited a fast response (2 s) and low detection limit (0.5 μM).     

Plane‐wave density functional theory investigation of adsorption of 2,4,6‐trinitrotoluene on al‐hydroxylated (0001) surface of (4 × 4) α‐alumina

This article reports the results of the theoretical investigation of adsorption of 2,4,6‐trinitrotoluene (TNT) on Al‐hydroxylated (0001) surface of (4 × 4) α‐alumina (α‐Al₂O₃) using plane‐wave Density Functional Theory. Sixteen water molecules were used to hydroxylate the alumina surface. The Perdew–Burke–Ernzerhof functional and the recently developed van der Waals functional (vdW‐DF2) were used. The interaction of electron with core was accounted using the Vanderbilt ultrasoft pseudopotentials. It was found that hydroxylation has significant influence on the geometry of alumina and such changes are prominent up to few layers from the surface. Particularly, due to the Al‐hydroxylation the oxygen layers are decomposed into sublayers and such partitioning becomes progressively weaker for interior layers. Moreover, the nature of TNT adsorption interaction is changed from covalent type on the pristine alumina surface to hydrogen‐bonding interaction on the Al‐hydroxylated alumina surface. TNT in parallel orientation forms several hydrogen bonds compared to that in the perpendicular orientation with hydroxyl groups of the Al‐hydroxylated alumina surface. Therefore, the parallel orientation will be present in the adsorption of TNT on Al‐hydroxylated (0001) surface of α‐alumina. Further, the vdW‐DF2 van der Waals functional was found to be most suitable and should be used for such surface adsorption investigation. © 2014 Wiley Periodicals, Inc.     

Characterization,optical, and nanoscale free volume properties of Na‐CMC/PAM/CNT nanocomposites

Polyblend and nanocomposite films of sodium salt of carboxymethylcellulose (Na‐CMC)/polyacrylamide (PAM) and Na‐CMC/PAM modified with carbon nanotubes (CNT) were synthesized by the solution casting technique. The effect of PAM and CNT loading on the structural, optical, and nanoscale free volume properties of Na‐CMC was studied. X‐ray diffraction (XRD) and Fourier transform infrared (FTIR) spectroscopy exhibited the existence of strong interactions between Na‐CMC and PAM and the non‐destructive effect of CNT on Na‐CMC/PAM structure. The HR‐TEM revealed the multi‐walled structure of CNT with a 7.06‐nm wall thickness and a 6.92‐nm wall inner diameter. Positron annihilation lifetime spectroscopy (PALS) was done, in a vacuum and at 30°C to 200°C, to investigate the nanoscale free volume properties by using a conventional fast‐fast coincidence spectrometer. It was found that the o‐Ps lifetime (τ₃ ) and free volume (V_h) increase with increasing CNT percentage in the Na‐CMC/PAM blend. The distribution of the o‐Ps lifetime was broadened with increasing CNT ratios. Furthermore, the glass transition temperature (T_g) increases with increasing loads of CNT. For the first time, a correlation was done between Urbach energy (E_U) and V_h. Finally, the results were represented and discussed in the frame of free volume properties. Optical measurements showed that the transmittance T% of Na‐CMC/PAM was 91.12% and decreased to 68.42% and 36.45% after loading with 1.0 and 2.0 wt % CNT. In addition, the blend shows higher insulating properties compared with the individual polymers. The CNT incorporation reduces the band gap significantly and increases the E_U in the films.     

PVC‐Based Ion‐Selective Electrodes with Enhanced Biocompatibility by Surface Modification with “Click” Chemistry

We report here on plasticized ion‐selective poly(vinyl chloride) membranes with increased biocompatibility by means of a copper(I)‐catalyzed azide‐alkyne cycloaddition (‘click chemistry’) on the surface of finished membranes. We aimed for increasing the hydrophilicity of the surface and the application of NO releasing molecules. Employing the first principle, sodium selective membranes based on azide‐substituted PVC were modified with different length poly(ethylene glycol) (PEG) chains. For the second, cysteine groups were used as a nitrous oxide releasing substance. Surface modification was confirmed by Electrochemical Impedance Spectroscopy (EIS). Potentiometric measurements in undiluted whole blood showed an increased sensor stability in comparison to unmodified PVC. Membrane surfaces after 18 h contact with blood were analyzed with Scanning Electron Microscopy (SEM) and revealed a reduced level of blood cell adsorption on membranes modified with tetraethylene glycol (TEG) and PEGs. In contrast, cysteine modified membranes did not exhibit improved fouling resistance, suggesting that nitric oxide release by itself is not a sufficiently efficient mechanism.     

Asymmetrically Functionalized,Four‐Armed,Poly(ethylene glycol) Compounds for Construction of Chemically Functionalizable Non‐Biofouling Surfaces

Asymmetrically functionalized, four‐armed, Tween 20 derivatives that formed stable monomolecular films on solid substrates were designed and synthesized. Thiol‐modified Tween 20 was used for forming self‐assembled monolayers (SAMs) on gold, and maleimide‐modified Tween 20 was introduced onto SiO₂ surfaces with SAMs of (3‐mercaptopropyl)trimethoxysilane through Michael addition. These structurally modified Tween 20 compounds gave the original characteristics of Tween 20, non‐biofouling (from ethylene glycol groups) and functionalizable (from OH groups) properties, to each substrate. The non‐biofouling properties of the Tween 20‐coated gold and SiO₂ surfaces were investigated by surface plasmon resonance spectroscopy and ellipsometry, and these surfaces showed strong resistance against nonspecific adsorption of proteins. In addition, the biospecific binding of streptavidin was achieved after coupling of (+)‐biotinyl‐3,6,9‐trioxaundecanediamine onto the non‐biofouling surfaces through amide‐bond formation.     

Biomimetic apatite formation and biocompatibility on chemically treated Ti‐6Al‐7Nb alloy

Alkali treatment of the Ti‐6Al‐7Nb alloys with subsequent heat treatment has been adopted as an important surface treatment procedure for apatite formation in dental implants. This study examined the effects of alkali treatment on the precipitation of apatite on a Ti‐6Al‐7Nb alloy. All samples were immersed in a Hanks' Balanced Salts Solution [simulated body fluid (SBF)] at pH 7.4 and 36.5 °C for 15 days. The surface structural changes of samples due to the alkali treatment and immersing in SBF were analyzed by XRD, SEM and XPS. The cell toxicity was evaluated based on the optical density of the surviving cells. The samples were implanted into the abdominal connective tissue of mice for 4 weeks. A sodium titanate hydrogel layer was formed after immersion in an NaOH solution. A dense and uniform bone‐like apatite layer precipitated on the alkali and heat‐treated Ti‐6Al‐7Nb alloy in the SBF. There was a significant difference in cell toxicity between the treated and untreated Ti‐6Al‐7Nb (P < 0.05). The thickness of the fibrous capsule formed around the implant body was decreased significantly by the alkali and heat treatment (P < 0.05). The alkali treatment samples showed a better biocompatibility than the commercial metal samples. Copyright © 2008 John Wiley & Sons, Ltd.