Porous Titanium Surface Research Articles

Porous Titanium Surfaces to Control Bacteria Growth: Mechanical Properties and Sulfonated Polyetheretherketone Coatings as Antibiofouling Approaches

Here, titanium porous substrates were fabricated by a space holder technique. The relationship between microstructural characteristics (pore equivalent diameter, mean free-path between pores, roughness and contact surface), mechanical properties (Young’s modulus, yield strength and dynamic micro-hardness) and bacterial behavior are discussed. The bacterial strains evaluated are often found on dental implants: Methicillin-resistant Staphylococcus aureus (MRSA) and Pseudomonas aeruginosa. The colony-forming units increased with the size of the spacer for both types of studied strains. An antibiofouling synthetic coating based on a sulfonated polyetheretherketone polymer revealed an effective chemical surface modification for inhibiting MRSA adhesion and growth. These findings collectively suggest that porous titanium implants designed with a pore size of 100–200 µm can be considered most suitable, assuring the best biomechanical and bifunctional anti-bacterial properties.

Fabrication and biological evaluation of the coating co‐doped strontium and zinc nanoparticles on porous pure titanium surface by hydrothermal method

Background For dental implants, early infection and peri-implantitis after implant restoration are major reasons for implant failure. Plaque biofilm formation is the initiator for implant-related infection. Therefore, it is urgent to develop a new antibacterial implant materials or treatment methods. Aim/Hypothesis In this study, Sr- and Zn- incorporated micro nano-structured titanium surface with nanorods (MNT-Sr Zn) was fabricated by a two-step hydrothermal process, aiming to improve osseointegration and reduce implant failure caused by implant-related infection and broaden new ideas for the future research Material and Methods The Mod Ti surfaces were used as a control. The characterization of different surfaces was detected by a field emission scanning electron microscope (FE-SEM) equipped with energy dispersive spectra (EDS) detector, x-ray diffractometer (XRD) and inductively coupled plasma mass spectroscopy (ICP-MS). Meanwhile, Staphylococcus aureus (S. aureus) was selected to evaluate antibacterial properties through Live Dead Staining and watching the adhesive bacterial morphology under FE-SEM. What's more, rat bone marrow-derived mesenchymal stem cells (rBMSCs) were cultured on the surfaces to detect their early osteogenic properties, like the alkaline phosphatase(ALP) activity and the expressions of osteogenesis related genes. Results The results confirmed that nanorod-like particles with a diameter of about 30-50 nm of MNT-Sr Zn composed of well-crystallized ZnO and SrTiO3 phases. In the EDS spectra, the elements of Zn and Sr were evenly distributed, and approximately 1.49 ± 0.16 wt% and 21.69 ± 2.74 wt% respectively. Besides, the release of Sr2+ and Zn2+ was a controlled and long-term process. More importantly, Zn-containing nanorod-like particles and the morphology could work together, slightly decreasing adhesion of S. aureus but increasing the proportion of dead cells, thus inhibiting subsequent biofilm formation, compared with the controlled group. In addition to this, MNT-Sr Zn could enhance the osteogenic differentiation via the upregulation of the transcription of osteogenic related genes and the expression of ALP in vitro. Conclusion and Clinical Implications This research provides a new surface modification method on titanium substrate for multi-functional implant material development. Due to the co-doping of Sr and Zn in the coating, biomechanical stability, antibacterial capability and early osteogenic inductive effect are enhanced, which has the potential to be applied in dental implantation in the future.

Fabrication and biological evaluation of titanium surfaces with multistage storage space for potential biomedical application

Bacterial infections are the main cause of failure in orthopedic implants, while drug delivery through a localized drug delivery platform is an effective solution. A novel hierarchical structure with multistage storage space was constructed in this study. Hole structures were firstly obtained by etching with a mixture of hydrogen peroxide and aqueous ammonia, and then the nanotube spaces were further constructed on this porous titanium surface by anodization. Results showed that holes of about 30 μm in diameter were formed on the etched surface when the volume concentration of ammonia water was 7%. These holes were homogeneously distributed and the inner walls were smooth. Importantly, titania nanotube arrays on the porous surface were still grown in order without defects. In addition, the modified surface possessed excellent hydrophilicity, and cell experiments have also shown that the platform exhibited enhancing cell proliferation, vitality and osteogenic differentiation, indicating better osseointegration. Finally, the application prospects of the constructed surfaces in the localized drug delivery platform for medical implants were discussed.

Application of Solution Plasma Surface Modification Technology to the Formation of Thin Hydroxyapatite Film on Titanium Implants

Hydroxyapatite (HA) coatings on titanium implants enhance rapid bone formation around the implant due to their osteoconductive property. The present study aimed to achieve a thin and uniform HA film coating on titanium implants by solution plasma treatment (SPT). Commercially pure titanium and porous titanium disks were employed. A pulse plasma generator was used on the disks for 30 min. Morphologic and crystallographic features of the deposited films were examined by scanning electron microscopy (SEM) and X-ray diffractometry (XRD). To evaluate the wettability of the disks, water droplet (20 µL) surfaces were measured using a contact angle analyzer. The initial attachment of osteoblast-like cells (MC3T3E1) on the titanium substrates before and after solution plasma treatment was evaluated by counting the number of attached cells after incubation for 4 h. After immersion in the mineralizing solution for up to seven days, no crystals were observed on the polished-Ti surface. A more uniform and dense precipitation of round and grown crystals with diameters of approximately 1–5 µm was observed on Ti-SPT. XRD clearly showed that the precipitated crystals on titanium disks were HA. The contact angle of the polished-Ti increased with time (θ = 37°–51°). The surface of the Ti-SPT remained hydrophilic (θ ˂ 5°) after up to 30 days of aging. The number of attached cells on the Ti-SPT after aging for 30 days remained above 85% of that on the Ti-SPT without aging. SPT in a mineralizing solution can be used to acquire a homogenous precipitation of HA on porous-surfaced titanium implants.

Effects of acid-alkali treatment on bioactivity and osteoinduction of porous titanium: An in vitro study

BackgroundTo elucidate the bioactivity and bone regeneration of porous titanium surfaces treated using acid-alkali combination, and to define the optimal alkali reaction time. MethodsTen groups of porous Ti with at least 3 per group undergoing different acid-alkali treated time were prepared. The surface was characterized by scanning electron microscopy (SEM), energy dispersive X-ray spectroscopy (EDS), bicinchoninic acid method (BCA), optical contact angle measurement and Raman spectrometry. Compression testing was performed with a universal testing machine. The bioactivity and osteoinduction were evaluated by a series of biological tests using a simulated body fluid (SBF) test, cell proliferation test, vinculin, ALP and OCN expression, and cell mineralization. ResultsThe acid-alkali treatment formed micro- and nano-scale structures on the sample surfaces. The alkali treatment for 12 h achieved the sharpest nano-scale surface relief and the most protein absorption. The treated porous surface was coated with a NaHTiO3 layer. The acid-alkali etching did not compromise the elastic modulus and compressive strength of the porous Ti samples. In addition to hydroxyapatite, a perovskite phase was also formed on the treated porous samples in SBF. Non-treated dense Ti showed more cell adhesion and proliferation (P < 0.05), while osteoinduction and mineralization were more pronounced on the treated porous sample (P < 0.05). ConclusionAcid-alkali treatment is an effective means of generating nano-scale relief on porous Ti surface, and is beneficial for bioactivity and bone regeneration. The 15 min acid and 12 h alkali etching is the optimal combination. The osteoinductive efficacy may be attributable to the surface physical chemistry and the formation of hydroxyapatite and perovskite layers, rather than direct cell adhesion and proliferation.

Bone loss management: A potpourri of options

Bone loss encountered during revision TKA can make proper alignment and fixation a challenge. Causes for bone loss in revision TKA include implant loosening, osteolysis, and iatrogenic from implant removal. Reproducible clinical success can be achieved if metaphyseal fixation is achieved [1]. In the absence of cancellous bone for cement fixation, metaphyseal augments placed without cement have shown promise in achieving fixation. First generation augments were modular solid titanium sleeves attached to a taper at the base of the core implant. The introduction of tantalum with its favorable mechanical qualities markedly increased the utility and utilization of metaphyseal augments, with several encouraging reports. These are either large augments where the bone is prepared with a burr, or later, small cones placed with a cannulated broaching technique. Both have addressed practical challenges, the first being limited by the reproducibility of bone preparation, and the second with excellent reproducibility of bone preparation but limited inner diameters. More recent highly porous titanium surfaces have further broadened the choices by allowing larger inner diameters to the cones, which allow the use of offset stems.This article aims to review the senior author's experience in managing bone loss in the revision TKA setting.

Friday, September 28, 2018 10:30 AM–12:00 PM abstracts: innovation, surface technology and biomechanics: 174. Surface topography and chemistry effects on PEEK and titanium osseointegration

BACKGROUND CONTEXT Nearly 500,000 spinal fusion surgeries are performed each year in the U.S. Interbody fusion devices have been used for decades to facilitate fusion across the disc space, yet debate continues over the optimal material and structure used for these devices. Current cages are primarily made from PEEK due to its radiolucency and bone-like stiffness. However, current smooth PEEK cages are often associated with fibrous encapsulation and implant migration. This poor response is often attributed to inherent material properties of PEEK. However, the smooth surface of conventional PEEK surfaces may equally impede osseointegration, particularly when considering that rough and porous surfaces of various non-PEEK materials elicit more favorable osseointegration compared to smooth surfaces. PURPOSE The current study aimed to assess the relative influence of surface topography and chemistry on PEEK osseointegration by investigating the osseous response to smooth, rough, and porous surface topographies possessing a PEEK or titanium surface chemistry. STUDY DESIGN/SETTING Preclinical implant osseointegration model in the proximal tibial metaphysis of the rat. OUTCOME MEASURES Osseointegration was assessed by calculating bone ingrowth percentage, histological tissue evaluation, and biomechanical pullout testing. METHODS Porous PEEK implants were created as described previously. Rough surfaces were created by soda-blasting PEEK surfaces and smooth surfaces maintained an as-machined surface finish. Half of each group was coated with a ∼30nm thick layer of TiO2 using atomic layer deposition (ALD) while the other half maintained their native PEEK chemistry. Sterile implants were implanted into the proximal tibial metaphyses of skeletally mature male Sprague Dawley rats. At 8 weeks, animals were euthanized and bone-implant interfaces were subjected to µCT analysis (n=12), histology (n=4), and biomechanical pullout testing (n=8). All data were reported as mean±SE. Comparisons between groups were calculated using a 2-way ANOVA followed by a Tukey multiple comparisons test. RESULTS Quantitative µCT analysis demonstrated that mineralized tissue ingrowth was 38.9±2.8% for porous PEEK and 30.7±3.3% for porous titanium (p=0.07). µCT tomograms and matching histological sections showed bone ingrowth in porous titanium surfaces primarily consisted of thin bone shells that conformed to the pore walls, leaving the center of pores devoid of bone. In contrast, bone ingrowth within porous PEEK was greater in the center of pores with periodic contact with pore walls. Greater bone-implant contact was observed for titanium compared to PEEK surfaces. Histological and µCT observations were corroborated by biomechanics outcomes. Across all groups both surface chemistry and topography had a significant overall effect on pullout force (p CONCLUSIONS The poor osseointegration of conventional PEEK implants may be linked more to their smooth surface topography rather than their material composition. The effect of surface topography (specifically porosity) dominated the effect of surface chemistry in this study and could lead to further improvements in orthopaedic device design.

Comparison of the Primary Stability of a Porous Coated Acetabular Revision Cup With a Standard Cup

BackgroundThe number of revision hip arthroplasty procedures has been increasing substantially, with the acetabular component requiring component revision in over half of the cases. New porous implant designs attempt to improve outcomes due to improved osseointegration; however, sufficient primary stability is paramount for good osseointegration. MethodsWe compared 2 revision cups of the same geometry, yet different surface properties in an in vitro scenario: a porous titanium surface and a conventional sintered-bead titanium surface. These were tested in 10 cadaveric pelvises under a physiologic cyclic partial weight-bearing scenario. Each side was randomly implanted with one of the implants. Relative motion between the bone and cup was measured using an optical measuring device. Statistical evaluation was carried out descriptively using a covariance analysis with repeated measures and a test of fixed effects, with significance determined as P < .05. ResultsThe conventional cup displayed an average relative motion of 28.02 μm; and the porous implant displayed an average relative motion of 33.42 μm. There was no statistically significant difference between the two with regard to the resultant relative motion (P = .2649). The bone mineral density does have a significant influence on resultant relative motion (P = .0406), with higher bone mineral density correlating with less relative motion in both implants. ConclusionThe porous implant provides similar primary stability to the conventional implant in the tested scenario; the motion of both implants relative to the bone was within safe limits for osseointegration. Bone stock must be considered when choosing implant type and postoperative care.

Adhesion of bone marrow mesenchymal stem cells on porous titanium surfaces with strontium-doped hydroxyapatite coating

ObjectiveTo determine the adhesion behavior of bone marrow mesenchymal stem cells (MSCs) on a titanium surface with a nanostructured strontium-doped hydroxyapatite (Sr-HA) coating.MethodsSr-HA coatings were applied on roughened titanium surfaces using an electrochemical deposition method. Primary cultured rat MSCs were seeded onto Sr-HA-, HA-coated titanium, and roughened titanium surfaces, and they were then cultured for 1, 6, and 24 h. 3-(4,5-Dimethylthiazol-2-yl)-2,5-diphenyltetrazolium bromide (MTT) assay was used to determine the metabolic condition of the cells. Scanning electron microscopy (SEM) was used to observe the cell morphology. The cytoskeletal structure was analyzed using fluorescence actin staining to characterize cell adherence. Quantitative real-time reverse transcription polymerase chain reaction (RT-qPCR) was used to analyze the gene expression levels of FAK (focal adhesion kinase), vinculin, integrin β1, and integrin β3 after culturing for 24, 48, and 72 h.ResultsMSCs cultured on the Sr-HA surface showed better cell proliferation and viability. Improvement of cell adhesion and structural rearrangement of the cytoskeleton were observed on the Sr-HA surface. The gene expression of FAK, vinculin, integrin β1, and integrin β3 was also elevated on the Sr-HA surface.ConclusionsCell viability, adhesion, cell morphology, and the cytoskeletal structure were all upregulated considerably by the titanium surface modified with a Sr-HA coating.

Production and Characterization of Porous Titanium Applied in Biomaterial

The development of materials with a porous titanium surface has been widely studied in the field of biomaterials due to the excellent biocompatibility, high corrosion resistance and combination of high strength with low density. Another relevant fact is that porosity allows bone tissue growth. However, the high reactivity in liquid state ends up hindering titanium fusion, so an alternative is the powder metallurgy (PM).The aim of this work was to produce porous titanium samples by conventional PM. Porous samples was characterized by porosity and microstructure (optical microscopy - OP and scanning electron microscopy SEM), crystaline phase (X-ray diffraction –XRD), mechanical properties (three point bending test) and cytotoxic test. The results showed the presence of alpha phase, a decrease in the elasticity modulus, increase in average pore size and samples exhibited no toxic effects.

Preparation and properties of low cost porous titanium by using rice husk as hold space

The present study demonstrates an effective low cost effective process for the production of porous titanium with 50–60vol% porosity using 20wt% rice husk (RH) with the hold spaces in the size ranges of 100–180, 180–250, 250–380, and 380–550µm. The analysis of the samples revealed an interconnected pore microstructure consisting of a mixture of coarse channel pores, created during burnout of RH. The compressive strength of the developed samples was in the range of 17–70MPa and depended strongly on their porosity and pore size. Large amounts of cleavage steps appeared on the brittle fracture surface after compression of the samples. The 3D morphology of porous titanium surface with rice husk sizes of 100–180µm and 380–550μm can be characterized by the micro-hole surface of pore size, and the size of the hole diameter and husk. The developed porous titanium is considered potentially useful in future medical or industrial application of biomass.

Multiscale porous titanium surfaces via a two-step etching process for improved mechanical and biological performance

Titanium (Ti)-based dental implants with multiscale surface topography have attracted great attention as a promising approach to enhance fixation and long-term stability of the implants, through the synergistic effect of nano- and microscale surface roughness, for accelerated bone regeneration and improved mechanical interlocking. However, structural integrity and mechanical stability of the multiscale roughened Ti surface under deformation need to be considered because significant deformation of dental implants is often induced during the surgical operation. Therefore, in this study, a well-defined nanoporous structure was directly introduced onto micro-roughened Ti surfaces through target-ion induced plasma sputtering (TIPS) with a tantalum (Ta) target, following sand-blasted, large-grit and acid-etching (SLA). This two-step etching process successfully created multiscale surface roughness on Ti with a minimal change of the pre-formed microscale roughness. Moreover, TIPS allowed the Ti surface to possess good mechanical stability under deformation and improved hydrophilicity, through altering the surface chemistry of brittle and hydrophobic SLA-treated Ti without formation of the interface between nanoporous and microporous structures. The in vitro and in vivo tests confirmed that multiscale roughened Ti significantly enhanced osteoblast attachment, proliferation and differentiation, which eventually led to improved bone regeneration and osseointegration, compared to smooth and micro-roughened Ti.

The fabrication of Ag-containing hierarchical micro/nano-structure on titanium and its antibacterial activity

Bacterial infections and insufficient osseointegration are two frequent problems for biomedical titanium implants. To improve the antibacterial activity and bioactivity, many strategies have recently focused on the modification of the surface composition and topography of titanium. However, relatively few efforts have been made to further enhance the antibacterial activity of a hierarchical micro/nano-structure. In this work, Ag-containing hierarchical hybrid micro/nano-structure was formed on titanium surface by magnetron sputtering, micro-arc oxidation and hydrothermal treatment for the first time. The unique nanoscale petal-shaped structure was formed on the micro-structured TiO2 coating surface after hydrothermal treatment and uniformly distributed on the porous titanium surface. The resulting surface displays good antibacterial property against Escherichia coli (E. coli). The synthesis method is a viable approach for improving the surface property of titanium-based biomedical devices.

Fortifying the Bone-Implant Interface Part 1: An In Vitro Evaluation of 3D-Printed and TPS Porous Surfaces.

An aging society and concomitant rise in the incidence of impaired bone health have led to the need for advanced osteoconductive spinal implant surfaces that promote greater biological fixation (e.g. for interbody fusion cages, sacroiliac joint fusion implants, and artificial disc replacements). Additive manufacturing, i.e. 3D-printing, may improve bone integration by generating biomimetic spinal implant surfaces that mimic bone morphology. Such surfaces may foster an enhanced cellular response compared to traditional implant surfacing processes. This study investigated the response of human osteoblasts to additive manufactured (AM) trabecular-like titanium implant surfaces compared to traditionally machined base material with titanium plasma spray (TPS) coated surfaces, with and without a nanocrystalline hydroxyapatite (HA) coating. For TPS-coated discs, wrought Ti6Al4V ELI was machined and TPS-coating was applied. For AM discs, Ti6Al4V ELI powder was 3D-printed to form a solid base and trabecular-like porous surface. The HA-coating was applied via a precipitation dip-spin method. Surface porosity, pore size, thickness, and hydrophilicity were characterized. Initial cell attachment, proliferation, alkaline phosphatase (ALP) activity, and calcium production of hFOB cells (n=5 per group) were measured. Cells on AM discs exhibited expedited proliferative activity. While there were no differences in mean ALP expression and calcium production between TPS and AM discs, calcium production on the AM discs trended 48% higher than on TPS discs (p=0.07). Overall, HA-coating did not further enhance results compared to uncoated TPS and AM discs. Results demonstrate that additive manufacturing allows for controlled trabecular-like surfaces that promote earlier cell proliferation and trends toward higher calcium production than TPS coating. Results further showed that nanocrystalline HA may not provide an advantage on porous titanium surfaces. Additive manufactured porous titanium surfaces may induce a more osteogenic environment compared to traditional TPS, and thus present as an attractive alternative to TPS-coating for orthopedic spinal implants.

Osteogenic activity and antibacterial effect of porous titanium modified with metal-organic framework films.

As a new class of crystalline nanoporous materials, metal-organic frameworks (MOFs) have recently been used for biomedical applications due to their large surface area, high porosity, and theoretically infinite structures. To improve the biological performance of titanium, MOF films were applied to surface modification of titanium. Zn-based MOF films composed of zeolitic imidazolate framework-8 (ZIF-8) crystals with nanoscale and microscale sizes (nanoZIF-8 and microZIF-8) were prepared on porous titanium surfaces by hydrothermal and solvothermal methods, respectively. The ZIF-8 films were characterized by powder X-ray diffraction (PXRD), Fourier transform infrared spectroscopy (FTIR), and scanning electron microscopy (SEM). The nanoZIF-8 film exhibited good biocompatibility, whereas the microZIF-8 film showed obvious cytotoxicity to MG63 cells. Compared to pure titanium and alkali- and heat-treated porous titanium, the nanoZIF-8 film not only enhanced alkaline phosphatase (ALP) activity, extracellular matrix mineralization, and expression of osteogenic genes (ALP, Runx2) in MG63 cells but also inhibited the growth of Streptococcus mutans. These results indicate that MOF films or coatings may be promising candidates for bone tissue engineering. © 2016 Wiley Periodicals, Inc. J Biomed Mater Res Part A: 105A: 834-846, 2017.

Combining 3D human in vitro methods for a 3Rs evaluation of novel titanium surfaces in orthopaedic applications.

ABSTRACTIn this study, we report on a group of complementary human osteoblast in vitro test methods for the preclinical evaluation of 3D porous titanium surfaces. The surfaces were prepared by additive manufacturing (electron beam melting [EBM]) and plasma spraying, allowing the creation of complex lattice surface geometries. Physical properties of the surfaces were characterized by SEM and profilometry and 3D in vitro cell culture using human osteoblasts. Primary human osteoblast cells were found to elicit greater differences between titanium sample surfaces than an MG63 osteoblast‐like cell line, particularly in terms of cell survival. Surface morphology was associated with higher osteoblast metabolic activity and mineralization on rougher titanium plasma spray coated surfaces than smoother surfaces. Differences in osteoblast survival and metabolic activity on titanium lattice structures were also found, despite analogous surface morphology at the cellular level. 3D confocal microscopy identified osteoblast organization within complex titanium surface geometries, adhesion, spreading, and alignment to the biomaterial strut geometries. Mineralized nodule formation throughout the lattice structures was also observed, and indicative of early markers of bone in‐growth on such materials. Testing methods such as those presented are not traditionally considered by medical device manufacturers, but we suggest have value as an increasingly vital tool in efficiently translating pre‐clinical studies, especially in balance with current regulatory practice, commercial demands, the 3Rs, and the relative merits of in vitro and in vivo studies. Biotechnol. Bioeng. 2016;113: 1586–1599. © 2015 The Authors. Biotechnology and Bioengineering Published by Wiley Periodicals, Inc.

Mussel-inspired silver-nanoparticle coating on porous titanium surfaces to promote mineralization

Porous titanium surfaces modified with mussel-inspired silver-nanoparticles for inhibiting bacterial adhesion and promoting mineralization and then improving osteoblast-biocompatibility.

Effect of pore size on bone ingrowth into porous titanium implants fabricated by additive manufacturing: An in vivo experiment

Selective laser melting (SLM) is an additive manufacturing technique with the ability to produce metallic scaffolds with accurately controlled pore size, porosity, and interconnectivity for orthopedic applications. However, the optimal pore structure of porous titanium manufactured by SLM remains unclear. In this study, we evaluated the effect of pore size with constant porosity on in vivo bone ingrowth in rabbits into porous titanium implants manufactured by SLM. Three porous titanium implants (with an intended porosity of 65% and pore sizes of 300, 600, and 900μm, designated the P300, P600, and P900 implants, respectively) were manufactured by SLM. A diamond lattice was adapted as the basic structure. Their porous structures were evaluated and verified using microfocus X-ray computed tomography. Their bone–implant fixation ability was evaluated by their implantation as porous-surfaced titanium plates into the cortical bone of the rabbit tibia. Bone ingrowth was evaluated by their implantation as cylindrical porous titanium implants into the cancellous bone of the rabbit femur for 2, 4, and 8weeks. The average pore sizes of the P300, P600, and P900 implants were 309, 632, and 956μm, respectively. The P600 implant demonstrated a significantly higher fixation ability at 2weeks than the other implants. After 4weeks, all models had sufficiently high fixation ability in a detaching test. Bone ingrowth into the P300 implant was lower than into the other implants at 4weeks. Because of its appropriate mechanical strength, high fixation ability, and rapid bone ingrowth, our results indicate that the pore structure of the P600 implant is a suitable porous structure for orthopedic implants manufactured by SLM.

Effect of Alkali-Acid-Heat Chemical Surface Treatment on Electron Beam Melted Porous Titanium and Its Apatite Forming Ability.

Advanced additive manufacturing techniques such as electron beam melting (EBM), can produce highly porous structures that resemble the mechanical properties and structure of native bone. However, for orthopaedic applications, such as joint prostheses or bone substitution, the surface must also be bio-functionalized to promote bone growth. In the current work, EBM porous Ti6Al4V alloy was exposed to an alkali acid heat (AlAcH) treatment to bio-functionalize the surface of the porous structure. Various molar concentrations (3, 5, 10M) and immersion times (6, 24 h) of the alkali treatment were used to determine optimal parameters. The apatite forming ability of the samples was evaluated using simulated body fluid (SBF) immersion testing. The micro-topography and surface chemistry of AlAcH treated samples were evaluated before and after SBF testing using scanning electron microscopy and energy dispersive X-ray spectroscopy. The AlAcH treatment successfully modified the topographical and chemical characteristics of EBM porous titanium surface creating nano-topographical features ranging from 200–300 nm in size with a titania layer ideal for apatite formation. After 1 and 3 week immersion in SBF, there was no Ca or P present on the surface of as manufactured porous titanium while both elements were present on all AlAcH treated samples except those exposed to 3M, 6 h alkali treatment. An increase in molar concentration and/or immersion time of alkali treatment resulted in an increase in the number of nano-topographical features per unit area as well as the amount of titania on the surface.

Osteoblast response to porous titanium and biomimetic surface: In vitro analysis.

This study analyzed the behavior of human osteoblasts cultured on porous titanium specimens, with and without biomimetic treatment, compared to dense titanium. The experiment had seven groups: Group 1: cells cultured on polystyrene of culture plate wells; Group 2: cells cultured on dense titanium specimen; Group 3: specimen with 33.79% of pores; Group 4: 41.79% of pores; Groups 5, 6 and 7: specimens similar to groups 2, 3 and 4, yet with biomimetic treatment. Real time-polymerase chain reaction with reverse transcription of the following genes was performed: prostaglandin E2 synthase, integrin β1, osterix, Runx2, Interleukin 6, macrophage colony stimulating factor, apolipoprotein E and others. The study achieved data on cell adhesion, growth and viability, total protein content, alkaline phosphatase activity and quantity of mineralized nodule formations. Data were statistically evaluated. Adherent cells and alkaline phosphatase activity were similar in titanium specimens, regardless of the groups. Biomimetic treatment reduced the total protein activity and the viability of tested cells. Most tested genes had statistically similar expression in all groups. The tested porosities did not cause alterations in osteoblast behavior and the biomimetic treatment impaired the biocompatibility of titanium causing cytotoxicity.