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Background: The diagnosis of joint replacement infection is a difficult clinical challenge that often occurs when the implant cannot be salvaged. We hypothesize that the pH value of synovial fluid could be an important indicator of the inflammatory status of the joint. However, in the literature, there is a lack of data on the pH changes in hip and knee joint replacements and their relation to infection and implant failure. In this study, we aimed to measure the pH levels of synovial fluid in patients with hip and knee joint replacements. We also investigated the potential of pH measurement as a diagnostic tool for joint replacement infection. In this study, we recorded the pH values to be 7.55 and 7.46 in patients where Pseudomonas aeruginosa was identified as the cause of the prosthetic joint infection. We attribute this to the different environments created by this specific bacterium. In other cases where the pH was higher, chronic mitigated infections were diagnosed, caused by strains of Staphylococcus aureus , Streptococcus agalactiase , and coagulase negative staphylococcus ., Materials and Methods: In our cohort of 155 patients with implanted hip (THA; n = 85) or knee (TKA; n = 70) joint replacements, we conducted a prospective study with a pH measurement. Out of the whole cohort, 44 patients had confirmed joint replacement infection (28.4%) (44/155). In 111 patients, infection was ruled out (71.6%) (111/155). Joint replacement infection was classified according to the criteria of the Musculoskeletal Infection Society (MSIS) from 2018. Based on the measured values, we determined the cut-off level for the probability of ongoing inflammation. We also determined the sensitivity and specificity of the measurement., Results: The group of patients with infection (n = 44) had a significantly lower synovial fluid pH (pH = 6.98 ± 0.48) than the group of patients with no infection (n = 111, pH = 7.82 ± 0.29, p < 0.001). The corresponding median pH values were 7.08 for the patients with infection and 7.83 for the patients with no infection. When we determined the cut-off level of pH 7.4, the sensitivity level of infected replacements was 88.6%, and the specificity level of the measurement was 95.5%. The predictive value of a positive test was 88.6%, and the predictive value of a negative test was 95.5%., Conclusions: Our results confirm that it is appropriate to include a pH measurement in the diagnostic spectrum of hip and knee replacements. This diagnostic approach has the potential to provide continuous in vivo feedback, facilitated by specialized biosensors. The advantage of this method is the future incorporation of a pH-detecting sensor into intelligent knee and hip replacements that will assess pH levels over time. By integrating these biosensors into intelligent implants, the early detection of joint replacement infections could be achieved, enhancing proactive intervention strategies.

Titanium surface treated with titanium oxide nanotubes was used in many studies to quantify the effect of surface topography on cell fate. However, the predicted optimal diameter of nanotubes considerably differs among studies. We propose a model that explains cell adhesion to a nanostructured surface by considering the deformation energy of cell protrusions into titanium nanotubes and the adhesion to the surface. The optimal surface topology is defined as a geometry that gives the membrane a minimum energy shape. A dimensionless parameter, the cell interaction index, was proposed to describe the interplay between the cell membrane bending, the intrinsic curvature, and the strength of cell adhesion. Model simulation shows that an optimal nanotube diameter ranging from 20 nm to 100 nm (cell interaction index between 0.2 and 1, respectively) is feasible within a certain range of parameters describing cell membrane adhesion and bending. The results indicate a possibility to tune the topology of a nanostructural surface in order to enhance the proliferation and differentiation of cells mechanically compatible with the given surface geometry while suppressing the growth of other mechanically incompatible cells.

Titanium beta alloys represent the new generation of materials for the manufacturing of joint implants. Their Young's modulus is lower and thus closer to the bone tissue compared to commonly used alloys. The surface tribological properties of these materials should be improved by ion implantation. The influence of this surface treatment on corrosion behaviour is unknown. The surface of Ti-36Nb-6Ta, Ti-36Nb-4Zr, and Ti-39Nb titanium β-alloys was modified using nitrogen ion implantation. X-ray photoelectron spectroscopy was used for surface analysis, which showed the presence of titanium, niobium, and tantalum nitrides in the treated samples and the elimination of less stable oxides. Electrochemical methods, electrochemical impedance spectra, polarisation resistance, and Mott-Schottky plot were measured in a physiological saline solution. The results of the measurements showed that ion implantation does not have a significant negative effect on the corrosion behaviour of the material. The best results of the alloys investigated were achieved by the Ti-36Nb-6Ta alloy. The combination of niobium and tantalum nitrides had a positive effect on the corrosion resistance of this alloy. After surface treatment, the polarization resistance of this alloy increased, 2.3 × 10 6 Ω·cm 2 , demonstrating higher corrosion resistance of the alloy. These results were also supported by the results of electrochemical impedance spectroscopy.

This paper evaluates the amount of KMnO 4 in simulated concrete pore solution (pH 12.8) on the corrosion behaviour of hot-dip galvanized steel (HDG). In the range of used MnO 4 - (10 -4 , 10 -3 , 10 -2 mol·L -1 ), corrosion behaviour is examined with regard to hydrogen evolution and composition (protective barrier properties) of forming corrosion products. The corrosion behaviour of HDG samples is evaluated using R p /E corr and EIS. The composition of corrosion products is evaluated using SEM, XRD, XPS and AAS. The effective MnO 4 - ion concentration to prevent the corrosion of coating with hydrogen evolution is 10 -3 mol·L -1 ; lower concentrations only prolong the time to passivation (corrosion with hydrogen evolution). The highest used MnO 4 - concentration ensures corrosion behaviour without hydrogen evolution but also leads to the formation of less-protective amorphous corrosion products rich in Mn II /Mn III phases.

In the field of orthopedic or dental implants, titanium and its alloys are most commonly used because of their excellent mechanical and corrosion properties and good biocompatibility. After implantation into the patient's body, there is a high risk of developing bacterial inflammation, which negatively affects the surrounding tissues and the implant itself. Early detection of inflammation could be done with a pH sensor. In this work, pH-sensitive systems based on TiO 2 -Ru and TiO 2 -RuO 2 combinations were fabricated and investigated. As a base material, Ti-6Al-4V alloy nanostructured by anodic oxidation was used. Ruthenium was successfully deposited on nanotubular TiO 2 using cyclic polarization, galvanostatic and potentiostatic mode. Potentiostatic mode proved to be the most suitable. The selected samples were oxidized by cyclic polarization to form a TiO 2 -RuO 2 system. The success of the oxidation was confirmed by XPS analysis. The electrochemical response of the systems to pH change was measured in saline solution using different techniques. The measurement of open circuit potential showed that unoxidized samples (TiO 2 -Ru) exhibited sub-Nernstian behavior (39.2 and 35.8 mV/pH). The oxidized sample (TiO 2 -RuO 2 ) containing the highest amount of Ru exhibited super-Nernstian behavior (67.3 mV/pH). The Mott-Schottky analysis proved to be the best method. The use of the electrochemical impedance method can also be considered, provided that greater stability of the samples is achieved.

Deep-sea manganese nodules are polymetallic oxidic ores that can be found on a seabed. Aluminothermic reduction is one of the possibilities of manganese nodules processing. This process obtains the polymetallic alloy with a high content of Mn and a varying content of Al, depending on the ratio between aluminum and nodules. The corrosion behaviors of three experimental Mn-based alloys produced by aluminothermic reduction with a content of Mn > 50 wt % were studied. The electrochemical testing in potable water and model seawater was used to explain the corrosion mechanism of Mn-based alloys. The results showed that the corrosion rate of experimental Mn-based alloy decreases with the increase in aluminum content in both potable water and model seawater. It was observed that the uniform corrosion of experimental Mn-based alloys is changed with an increase in aluminum content in alloy to localized corrosion, which was caused by microcells in an environment of model seawater. In contrast, the formation of a semi-protective layer of corrosion products was observed on the surface of Mn-based alloys with a higher content of aluminum in potable water. Moreover, the pitting corrosion of tested Mn-based alloys was observed neither in potable water nor in model seawater.

Zinc (Zn) alloys seem to be promising candidates for application in orthopaedic or cardiovascular medical implants. In this area, high standards are required regarding the biocompatibility as well as excellent mechanical and tailored degradation properties. In the presented study, a novel Zn-0.8Mg-0.2Sr (wt%) alloy has been fabricated by the combination of casting, homogenization annealing and extrusion at 200 °C. As a consequence of its fine-grained homogenous microstructure, the prepared material is characterized by an excellent combination of tensile yield strength, ultimate tensile strength and elongation corresponding to 244 MPa, 324 MPa and 20% respectively. The in vitro corrosion rates of the Zn-0.8Mg-0.2Sr alloy in the physiological solution and the simulated body fluid were 244 μm/a and 69.8 μm/a, respectively. Furthermore, an extract test revealed that Zn-0.8Mg-0.2Sr extracts diluted to 25% had no adverse effects towards L929 fibroblasts, TAg periosteal cells and Saos-2 osteoblasts. Moreover, the Zn-0.8Mg-0.2Sr surface showed effective inhibition of initial Streptococcus gordonii adhesion and biofilm formation. These results indicated the Zn-0.8Mg-0.2Sr alloy, which has superior mechanical properties, might be a promising candidate for materials used for load-bearing applications., (Copyright © 2021. Published by Elsevier B.V.)

The chemical and phase composition of the coating and the coating/substrate interface of an Al-Si-coated 22MnB5 hot stamped steel was investigated by means of SEM-EDS, XRD, micro-XRD and electron diffraction. Moreover, the surface profile was analyzed by XPS and roughness measurements. The XPS measurements showed that the thickness of the Si and Al oxide layers increased from 14 to 76 nm after die-quenching, and that the surface roughness increased as well as a result of volume changes caused by phase transformations. In addition to the FeAl(Si) and Fe 2 Al 5 phases and the interdiffusion layer forming complex structures in the coating, electron diffraction confirmed the presence of an Fe 2 Al 5 phase, and also revealed very thin layers of Fe 3 (Al,Si)C, Fe 2 (Al,Si) 5 and Al-bearing rod-shaped particles in the immediate vicinity of the steel interface. Moreover, the scattered nonuniform layer of the Fe 2 Al 8 Si phase was identified in the outermost layer of the coating. Despite numerous studies devoted to researching the phase composition of the Al-Si coating applied to hot stamped steel, electron diffraction revealed very thin layers and particles on the coating/substrate interface and outermost layer, which have not been analyzed in detail.

Additive manufacturing technologies allow producing a regular three-dimensional mesh of interconnected struts that form an open-cell porous structure. Regular porous structures have been used in the orthopedic industry due to outstanding bone anchoring. The aim of the study was to determine how the postprocessing influences the mechanical properties of porous structures made of titanium alloy CL 41TI ELI. The effect of hot isostatic pressing (HIP) as a method of increasing microstructural integrity was investigated here. The influence of surface etching (SE) technique, which was applied to the porous structure for cleaning unmelted titanium powder particles on the surface of connectors from the inner surfaces of a porous structure, was examined in this study. Mechanical properties were investigated by means of compression tests. The results point out that HIP has a minor effect on the mechanical behavior of considered porous structures. The SE is an effective method to clean the surface of a porous structure, which is very important in the case of biomedical applications when loose powder can cause serious health problems. Another effect of the SE is also the strut thickness reduction. Reducing strut thickness of a porous structure with the surface etching decreases its stiffness to the same extent as predicted by the relative density theoretical model but did not result in structural damage.

The impact of four pre-treatment techniques on the surface morphology and chemistry, residual stress, mechanical properties, corrosion resistance in a physiological saline solution and cell colonization of commercially pure titanium is examined in detail. Mechanical polishing, electrochemical etching, chemical etching in Kroll's reagent, and ion sputter etching with argon ions were applied. Surface morphologies reflect the nature of surface layer removal. Significant roughening of the surface and a characteristic microtopology become apparent as a result of the sensitivity of chemical and ion sputter etching to the grain orientation. The hardness in the near surface region was controlled by the amount of residual stress. Etching of the stressed surface layer led to a reduction in residual stress and surface hardness. A compact passivation layer composed of TiO, TiO 2 and Ti 2 O 3 native oxides imparted high corrosion resistance to the surface after mechanical polishing, chemical and electrochemical etching. The ion sputter etched surface showed substantially reduced corrosion resistance, where the corrosion process was controlled by electron transfer. The specific topology affected the adhesion of the cell to the surface rather than the cell area coverage. The cell area coverage increased with the corrosion stability of the surface., Competing Interests: Declaration of competing interest The authors declare that they have no known competing financial interests or personal relationships that could have appeared to influence the work reported in this paper., (Copyright © 2020 Elsevier B.V. All rights reserved.)

Aim: To evaluate the impact of a nanostructured surface created on β-titanium alloy, Ti-36Nb-6Ta, on the growth and differentiation of human mesenchymal stem cells. Materials & methods: The nanotubes, with average diameters 18, 36 and 46 nm, were prepared by anodic oxidation. Morphology, hydrophilicity and mechanical properties of the nanotube layers were characterized. The biocompatibility and osteogenic potential of the nanostructured surfaces were established using various in vitro assays, scanning electron microscopy and confocal microscopy. Results: The nanotubes lowered elastic modulus close to that of bone, positively influenced cell adhesion, improved ALP activity, synthesis of type I collagen and osteocalcin expression, but diminished early cell proliferation. Conclusion: Nanostructured Ti-36Nb-6Ta with nanotube diameters 36 nm was the most promising material for bone implantation.

External fixators of serious fractures could be an attractive substrate on which microorganisms can accumulate. Therefore, this study aimed to develop a suitable method for enabling the simulation of a real situation when osteosynthetic fixation material is open for the potential threat of bacterial attack. Agar-based media represented human tissue, and the metallic pin characterized the screw in the fixation. Various types of agar, supplements, and contamination strategy by Staphylococcus aureus were tested. The influence of the initial bacterial concentration was also examined. Surfaces were observed by scanning electron microscopy (SEM), and all results were compared. Brain Heart Infusion Agar with the Egg Yolk Tellurite Emulsion was established in a transparent test tube as a suitable system for enabling the good interpretability of bacterial contamination in the pin's surroundings. Pin contamination has been found to be an appropriate approach for testing microbial growth, rather than agar surface contamination, which distorted obtained results. A lower initial colony forming units (CFU) provided better clarity of the test. SEM observation of the pin surface was comparable with the visual evaluations in the test tubes. Results were assembled for positive and negative control samples as well. Screening method for the most common bacteria S. aureus has been standardized and developed. This experimental setup could also be a useful tool for surface modification with antibacterial properties testing.

Titanium and its alloys are widely used for substitution of hard tissues, especially in orthopaedic and dental surgery. Despite the benefit of the use of titanium for such applications, there are still questions which must be sorted out. Surface properties are crucial for cell adhesion, proliferation and differentiation. Mainly, micro/nanostructured surfaces positively influence osteogenic differentiation of human mesenchymal stem cells. Ti 6 Al 4 V is a biocompatible α + β alloy which is widely used in orthopaedics. The aim of this study was to investigate the interaction of the nanostructured and ground Ti 6 Al 4 V titanium alloys with simulated body fluid complemented by the defined precipitation of hydroxyapatite-like coating and to study the cytotoxicity and differentiation capacity of cells with such a modified titanium alloy. Nanostructures were fabricated using electrochemical oxidation. Human mesenchymal stem cells (hMSC) were used to evaluate cell adhesion, metabolic activity and proliferation on the specimens. The differentiation potential of the samples was investigated using PCR and specific staining of osteogenic markers collagen type I and osteocalcin. Our results demonstrate that both pure Ti 6 Al 4 V, nanostructured samples, and hydroxyapatite-like coating supported hMSC growth and metabolic activity. Nanostructured samples improved collagen type I synthesis after 14 days, while both nanostructured and hydroxyapatite-like coated samples enhanced collagen synthesis on day 21. Osteocalcin synthesis was the most enhanced by hydroxyapatite-like coating on the nanostructured surfaces. Our results indicate that hydroxyapatite-like coating is a useful tool guiding hMSC osteogenic differentiation., Competing Interests: There are no conflicts to declare., (This journal is © The Royal Society of Chemistry.)

Titanium biomaterials are widely used in the medical field due to their biocompatibility and excellent corrosion and mechanical resistance. However, these materials have no antibacterial properties. To obtain an antibacterial active surface, a nanostructure of Ti6Al4V alloy was created. This specific nanostructure contained nanotubes and micro-cavities and was used as a substrate for silver anchoring. The electrochemical approach to silver reduction was studied. It is a common approach for silver deposition and in this work, inhomogeneities in the nanostructure were used as a preferential area for silver localisation. The galvanostatic regimen of deposition allowed for a technically quantitative process and the required silver placement. The experimental conditions used enabled testing and silver dissolution rate evaluation within a reasonable time span. Based on the corrosion and analytical results (EDS, XPS and ICP-MS), a two-phase silver release mechanism was confirmed. The openings of the individual nanotubes were filled with silver nanoparticles, whose release was relatively fast. By contrast, the silver anchored inside the cavities allowed the silver to release gradually. Antibacterial efficiency against Staphylococcus aureus and Escherichia coli was successfully demonstrated. Cytotoxicity testing with murine fibroblasts showed cell metabolic activity far above the normative limit of 70%., (Copyright © 2019 Elsevier B.V. All rights reserved.)

The formation of nanostructures on titanium implant surfaces is a promising strategy to modulate cell adhesion and differentiation, which are crucial for future application in bone regeneration. The aim of this study was to investigate how the nanotube diameter and/or nanomechanical properties alter human osteoblast like cell (Saos-2) adhesion, growth and osteogenic differentiation in vitro . Nanotubes, with diameters ranging from 24 to 66 nm, were fabricated on a commercially pure titanium (cpTi) surface using anodic oxidation with selected end potentials of 10 V, 15 V and 20 V. The cell response was studied in vitro on untreated and nanostructured samples using a measurement of metabolic activity, cell proliferation, alkaline phosphatase activity and qRT-PCR, which was used for the evaluation of osteogenic marker expression (collagen type I, osteocalcin, RunX2). Early cell adhesion was investigated using SEM and ELISA. Adhesive molecules (vinculin, talin), collagen and osteocalcin were also visualized using confocal microscopy. Moreover, the reduced elastic modulus and indentation hardness of nanotubes were assessed using a TriboIndenter™. Smooth and nanostructured cpTi both supported cell adhesion, proliferation and bone-specific mRNA expression. The nanotubes enhanced collagen type I and osteocalcin synthesis, compared to untreated cpTi, and the highest synthesis was observed on samples modified with 20 V nanotubes. Significant differences were found in the cell adhesion, where the vinculin and talin showed a dot-like distribution. Both the lowest reduced elastic modulus and indentation hardness were assessed from 20 V samples. The nanotubes of mainly 20 V samples showed a high potential for their use in bone implantation., Competing Interests: There are no conflicts to declare., (This journal is © The Royal Society of Chemistry.)

3D printing seems to be the technology of the future for the preparation of metallic implants. For such applications, corrosion behaviour is pivotal. However, little is published on this topic and with inconsistent results. Therefore, we carried out a complex study in which we compared two techniques of the 3D printing technology - selective laser melting and electron beam melting. The corrosion behaviour was studied in physiological solution by standard electrochemical techniques and susceptibility to localised corrosion was estimated too. All samples showed typical passive behaviour. Localised corrosion was shown to be possible on the original as-printed surfaces. Corrosion experiments were repeated tree times. To reveal possible negative effects of 3D printing on cytocompatibility, direct in vitro tests were performed with U-2 OS cells. The cells showed good viability and proliferation, but their growth was impeded by surface unevenness. Our results suggest that both techniques are suitable for implants production. Statistical evaluation was performed by ANOVA followed by Tukey's test., (Copyright © 2018 Elsevier B.V. All rights reserved.)

Thermal plasma spray is a common, well-established technology used in various application fields. Nevertheless, in our work, this technology was employed in a completely new way; for the preparation of bulk titanium. The aim was to produce titanium with properties similar to human bone to be used for bone augmentations. Titanium rods sprayed on a thin substrate wire exerted a porosity of about 15%, which yielded a significant decrease of Young's modulus to the bone range and provided rugged topography for enhanced biological fixation. For the first verification of the suitability of the selected approach, tests of the mechanical properties in terms of compression, bending, and impact were carried out, the surface was characterized, and its compatibility with bone cells was studied. While preserving a high enough compressive strength of 628 MPa, the elastic modulus reached 11.6 GPa, thus preventing a stress-shielding effect, a generally known problem of implantable metals. U-2 OS and Saos-2 cells derived from bone osteosarcoma grown on the plasma-sprayed surface showed good viability., Competing Interests: The authors declare no conflicts of interest. The founding sponsors had no role in the design of the study; in the collection, analyses, or interpretation of data; in the writing of the manuscript; or in the decision to publish the results.

Porous structures, manufactured of a biocompatible metal, mimicking human bone structure are the future of orthopedic implantology. Fully porous materials, however, suffer from certain drawbacks. To overcome these, gradient in structure can be prepared. With gradient in porosity mechanical properties can be optimized to an appropriate value, implant can be attributed a similar gradient macrostructure as bone, tissue adhesion may be promoted and also various modification with organic or inorganic substances are possible. In this study, additive technology selective laser melting (SLM) was used to produce three types of gradient porosity model specimens of titanium alloy Ti-6Al-4V. As this technology has the potential to prepare complex structures in the near-net form, to control porosity, pore size and shape, it represents a promising option. The first part of the research work was focused on the characterization of the material itself in the as-produced state, only with heat treatment applied. The second part dealt with the influence of porosity on mechanical properties. The study has shown SLM brings significant changes in the surface chemistry. Despite this finding, titanium alloy retained its cytocompatibility, as it was outlined by in vitro tests with U-2 OS cells. With introduced porosity yield strength, ultimate strength and stiffness showed linear decrease, both in tension and compression. With respect to the future use in the form of orthopedic implant, especially reduction in Young's modulus down to the human bone value (30.5±2GPa) is very appreciated as the stress-shielding effect followed by possible implant loosening is limited., (Copyright © 2017 Elsevier Ltd. All rights reserved.)

Recently, porous metallic materials have been extensively studied as candidates for use in the fabrication of scaffolds and augmentations to repair trabecular bone defects, e.g. in surroundings of joint replacements. Fabricating these complex structures by using common approaches (e.g., casting and machining) is very challenging. Therefore, rapid prototyping techniques, such as selective laser melting (SLM), have been investigated for these applications. In this study, we characterized a highly porous (87 vol.%) 316L stainless steel scaffold prepared by SLM. 316L steel was chosen because it presents a biomaterial still widely used for fabrication of joint replacements and, from the practical point of view, use of the same material for fabrication of an augmentation and a joint replacement is beneficial for corrosion prevention. The results are compared to the reported properties of two representative nonporous 316L stainless steels prepared either by SLM or casting and subsequent hot forging. The microstructural and mechanical properties and the surface chemical composition and interaction with the cells were investigated. The studied material exhibited mechanical properties that were similar to those of trabecular bone (compressive modulus of elasticity ~0.15GPa, compressive yield strength ~3MPa) and cytocompatibility after one day that was similar to that of wrought 316L stainless steel, which is a commonly used biomaterial. Based on the obtained results, SLM is a suitable method for the fabrication of porous 316L stainless steel scaffolds with highly porous structures., (Copyright © 2016 Elsevier B.V. All rights reserved.)

Degradable zinc-based alloys with an appropriate corrosion rate are promising materials for the preparation of temporary orthopaedic implants. Previously, we prepared and characterised a novel Zn1.5Mg alloy. This paper is focused on the characterisation of this alloy after a surface pre-treatment, which should mimic processes occurring in vivo. The samples of the Zn1.5Mg alloy were immersed in a simulated body fluid (SBF) at 37°C for 14days in order to form a protective layer of corrosion products. Thereafter, these samples were used for the corrosion rate determination, an indirect in vitro cytotoxicity test, as well as for a direct contact test and were compared with the non-treated samples. The protective layer was characterized by SEM and its chemical composition was determined by EDS and XPS analysis. The corrosion rate was significantly decreased after the pre-incubation. The protective layer of corrosion products was rich in Ca and P. The pre-incubated samples exhibited increased cytocompatibility in the indirect test (metabolic activity of L929 cells was above 70%) and we also observed osteoblast-like cell growth directly on the samples during the contact tests. Thus, the pre-incubation in SBF leading to improved cytocompatibility could represent more appropriate model to in vivo testing., (Copyright © 2015 Elsevier B.V. All rights reserved.)

Nanotubes with diameters ranging from 40 to 60nm were prepared by electrochemical oxidation of the Ti-6Al-4V alloy in electrolyte containing ammonium sulphate and ammonium fluoride. The nanotubes were further modified with calcium and phosphate ions or were heat treated. Polished Ti-6Al-4V alloy served as a reference sample. The spreading of human osteoblast-like cells was similar on all nanotube samples but lower than on polished samples. The number of initially adhered cells was higher on non-modified nanotubes, but the final cell number was the highest on Ca-enriched nanotubes and the lowest on heat-treated nanotubes. However, these differences were relatively small and less pronounced than the differences in the concentration of specific molecular markers of cell adhesion and differentiation, estimated by their intensity of immunofluorescence staining. The concentration of vinculin, i.e. a protein of focal adhesion plaques, was the lowest on nanotubes modified with calcium. Collagen I, an early marker of osteogenic cell differentiation, was also the lowest on samples modified with calcium and was highest on polished samples. Alkaline phosphatase, a middle marker of osteogenic differentiation, was observed in lowest concentration on nanotubes modified with phosphorus and the highest on heat-treated samples. Osteocalcin concentrations, a late marker of osteogenic cell differentiation, were similar on all tested samples, although they tended to be the highest on heat-treated samples. Thus, osteogenic differentiation can be modulated by various additional treatments of nanotube coatings on Ti-6Al-4V implants., (Copyright © 2016 Elsevier B.V. All rights reserved.)

Ti-6Al-4V-based nanotubes were prepared on a Ti-6Al-4V surface by anodic oxidation on 10 V, 20 V, and 30 V samples. The 10 V, 20 V, and 30 V samples and a control smooth Ti-6Al-4V sample were evaluated in terms of their chemical composition, diameter distribution, and cellular response. The surfaces of the 10 V, 20 V, and 30 V samples consisted of nanotubes of a relatively wide range of diameters that increased with the voltage. Saos-2 cells had a similar initial adhesion on all nanotube samples to the control Ti-6Al-4V sample, but it was lower than on glass. On day 3, the highest concentrations of both vinculin and talin measured by enzyme-linked immunosorbent assay and intensity of immunofluorescence staining were on 30 V nanotubes. On the other hand, the highest concentrations of ALP, type I collagen, and osteopontin were found on 10 V and 20 V samples. The final cellular densities on 10 V, 20 V, and 30 V samples were higher than on glass. Therefore, the controlled anodization of Ti-6Al-4V seems to be a useful tool for preparing nanostructured materials with desirable biological properties.

To increase an orthopedic implant's lifetime, researchers are now concerned on the development of new titanium alloys with suitable mechanical properties (low elastic modulus-high fatigue strength), corrosion resistance and good workability. Corrosion resistance of the newly developed titanium alloys should be comparable with that of pure titanium. The effect of medical preparations containing fluoride ions represents a specific problem related to the use of titanium based materials in dentistry. The aim of this study was to determine the corrosion behavior of β titanium alloy Ti-39Nb in physiological saline solution and in physiological solution containing fluoride ions. Corrosion behavior was studied using standard electrochemical techniques and X-ray photoelectron spectroscopy. It was found that corrosion properties of the studied alloy were comparable with the properties of titanium grade 2. The passive layer was based on the oxides of titanium and niobium in several oxidation states. Alloying with niobium, which was the important part of the alloy passive layer, resulted in no significant changes of corrosion behavior. In the presence of fluoride ions, the corrosion resistance was higher than the resistance of titanium., (Copyright © 2015 Elsevier B.V. All rights reserved.)

DLC-type layers offer a good potential for application in medicine, due to their excellent tribological properties, chemical resistance, and bio-inert character. The presented study has verified the possibility of alloying DLC layers with titanium, with coatings containing three levels of titanium concentration prepared. Titanium was present on the surface mainly in the form of oxides. Its increasing concentration led to increased presence of titanium carbide as well. The behavior of the studied systems was stable during exposure in a physiological saline solution. Electrochemical impedance spectra practically did not change with time. Alloying, however, changed the electrochemical behavior of coated systems in a significant way: from inert surface mediating only exchange reactions of the environment in the case of unalloyed DLC layers to a response corresponding rather to a passive surface in the case of alloyed specimens. The effect of DLC layers alloying with titanium was tested by the interaction with a simulated body fluid, during which precipitation of a compound containing calcium and phosphorus--basic components of the bone apatite--occurred on all doped specimens, in contrast to pure DLC. The results of the specimens' surface colonization with cells test proved the positive effect of titanium in the case of specimens with a medium and highest content of this element.

Porous materials allow for easier osseointegration of implants and their firmer connection with the bone. The presence of pores in a material may become a source of both mechanical and corrosion problems. The presented study explored a Ti-39Nb alloy with a porosity of 0-33%. Specimens were exposed in the physiological solution of two pH values. In view of this material's possible use in dental applications, the effect of fluoride ions on its corrosion behaviour was studied. The open circuit potential and polarization resistance were measured. Data concerning susceptibility to crevice corrosion were obtained from potentiostatic measurements based on the ASTM F746 standard. In terms of corrosion behaviour, specimens with a lower porosity were not much different from the non-porous material. Porosity produced its effect at the level of 24 and 33%. It is obvious that porosity affects corrosion behaviour of this type of material. This conclusion was confirmed by measurements of susceptibility to crevice corrosion which grew with the specimens' increasing porosity. Corrosion resistance of the Ti-39Nb alloy was comparable with that of the compact material, but the presence of pores initiated a local attack of the material.

Nowadays, a wide range of materials for human implants is used. To reach the required properties of implants, coatings are applied in some cases. This contribution is focused on the corrosion properties of TiN and ZrN layers on cp-titanium (commercially pure titanium) under environment modelling conditions in an oral cavity. Measurements were done in artificial saliva and a physiological solution unbuffered and buffered to a pH value of 4.2 with the addition of fluoride ions up to 4000 ppm. Standard corrosion electrochemical techniques were applied. Both types of layers were stable in both model saliva and physiological solution with non-adjusted pH. The decrease in pH to 4.2 resulted in a minor decrease of corrosion resistance in all cases, but polarization resistance was still in the order of 10(5) Ω cm². An important change in a specimens' behaviour was noticed in the presence of fluoride ions. TiN was stable in the highest concentration of fluorides used. The ZrN layers were destabilized in an environment containing a few hundred ppm of fluoride ions. As for TiN, the decisive factor is the influence of porosity; the corrosion resistance of ZrN is limited. From the corrosion point of view, the application of the TiN-based barrier layers in dental implantology is more advisable than the use of ZrN, provided that the application of a barrier is inevitable.

The negative effect of fluoride ions on titanium has been known in dentistry for a long time. The presented work was aimed at the interaction between titanium and model saliva following a short-term exposure of a specimen to a model medical preparation rich in fluoride ions. The experimental work was carried out using titanium grade 2 in a physiological solution (pH non-adjusted, 5.8, 4.2; 5000 ppm F-) and in model saliva. Electrochemical measurement techniques were supplemented with XPS analysis. The presence of fluoride ions resulted in partial degradation of the passive layer even in a slightly acidic environment. The decrease of pH to the value of 4.2 and the presence of 5000 ppm F- caused titanium activation followed by a slow repassivation in model saliva. Formation of low soluble compound rich in fluorine explains experimental data. Short medical treatment can result in relatively long period of increased titanium corrosion.