The relative influence of the topography and chemistry of TiAl6V4 surfaces on osteoblastic cell behaviour

Evaluation of Osteoconductive and Antimicrobial Properties of Novel Graphene on Dental Implants: An In Vitro Study

Introduction Graphene oxide (GO) has emerged as a promising material in dentistry, leveraging its exceptional properties. This study evaluates the physicochemical attributes of GO and elucidates its derived biological properties. These encompass biocompatibility, antibacterial efficacy, as well as its influence on osteogenic and odontogenic differentiation processes. Understanding the intricate interplay between the physicochemical and biological aspects of GO provides valuable insights into its potential applications in various dental contexts. Materials and methods The study group (so; titanium discs surface coated with GO) and the control group (co; plain/uncoated machined titanium discs) were divided based on cell attachment and cell proliferation assays (n=60). These groups were further divided into subgroups (n=30) based on the tested time intervals, specifically 24 hours, 48 hours, and 72 hours. The study and controlgroups were further subdivided into three subgroups (n=10) based on the microorganisms tested i.e Porphyromonas gingivalis, Prevotella intermedia and Fusobacteria nucleatum. Results The results of this in vitro study suggest that GO-coated titanium dental implants have both increased osteogenic potential and antimicrobial efficacy. Graphene has good potential as a promising alternative to traditional surface treatments, and a graphene-coated implant can be used for enhanced osseointegration.  Conclusion The osteogenic potential and the cell attachment were higher on titanium surfaces coated with GO nanoparticles when compared to plain titanium discs at 24, 48 and 72 hours respectively.

Genome-wide transcriptional responses of osteoblasts to different titanium surface topographies

This is the first genome-wide transcriptional profiling study using RNA-sequencing to investigate osteoblast responses to different titanium surface topographies, specifically between machined, smooth and acid-etched, microrough surfaces. Rat femoral osteoblasts were cultured on machine-smooth and acid-etched microrough titanium disks. The culture system was validated through a series of assays confirming reduced osteoblast attachment, slower proliferation, and faster differentiation on microrough surfaces. RNA-sequencing analysis of osteoblasts at an early stage of culture revealed that gene expression was highly correlated (r = 0.975) between the two topographies, but 1.38 % genes were upregulated and 0.37 % were downregulated on microrough surfaces. Upregulated transcripts were enriched for immune system, plasma membrane, response to external stimulus, and positive regulation to stimulus processes. Structural mapping confirmed microrough surface-promoted gene sharing and networking in signaling pathways and immune system/responses. Target-specific pathway analysis revealed that Rho family G-protein signaling pathways and actin genes, responsible for the formation of stress fibers, cytoplasmic projections, and focal adhesion, were upregulated on microrough surfaces without upregulation of core genes triggered by cell-to-cell interactions. Furthermore, disulfide-linked or -targeted extracellular matrix (ECM) or membranous glycoproteins such as laminin, fibronectin, CD36, and thrombospondin were highly expressed on microrough surfaces. Finally, proliferating cell nuclear antigen (PCNA) and cyclin D1, whose co-expression reduces cell proliferation, were upregulated on microrough surfaces. Thus, osteoblasts on microrough surfaces were characterized by upregulation of genes related to a wide range of functions associated with the immune system, stress/stimulus responses, proliferation control, skeletal and cytoplasmic signaling, ECM-integrin receptor interactions, and ECM-membranous glycoprotein interactions, furthering our knowledge of the surface-dependent expression of osteoblastic biomarkers on titanium.

Response of preosteoblasts on micromachined Ti-6Al-4V surface to microstructure dimension

The cell incubation depends on the cultured surface, but various machining methods produce different surface topographies, but it has not been clear how it is related to the topographic feature until now. Hence, the machined Ti-6Al-4V surface is characterized for preosteoblasts incubation via different mechanical fabrication. The relationship between surface topography created by various machining methods and cell incubation behaviour was explored. The objective is to control the surface preosteoblasts growth in machining of biological titanium alloy. According to the cell growth kinetic, the cell incubation behaviour was first proposed and modelled in relation to microstructural dimension and culture duration. Then, the topological cultured microstructure surface was fabricated via mechanical fabrication. Finally, the cell initial adhesion and incubation behaviour on microstructured surface was investigated. It is shown that the surface undulation on machined microstructure is conducive to controlling the direction and distribution of cell incubation from cell growth kinetic model. The cell culture can be controlled on the peak with a small undulation, while it is concentred on the sidewall with a high aspect ratio. Increasing the aspect ratio extends cell growth, while low aspect ratio promotes initial cell adhesion and growth rate. Within the optimal cultured duration, the microstructured surface is more favourable for cell survival, and the cell growth keep positive beyond critical aspect ratio. As a result, the cell adhesion ability is topologically controlled to 5.4 times higher and the growth rate can be improved by 101.7% on milled microgrooved surface. It may be applied to the rapid production of biomedical Ti-6Al-4V implant.

3D porous bioceramic based boron-doped hydroxyapatite/baghdadite composite scaffolds for bone tissue engineering

Making composite scaffolds is one of the well-known methods to improve the properties of scaffolds used in bone tissue engineering. In this study, novel ceramic-based 3D porous composite scaffolds were successfully prepared using boron-doped hydroxyapatite, as the primary component, and baghdadite, as the secondary component. The effects of making composites on the properties of boron-doped hydroxyapatite-based scaffolds were investigated in terms of physicochemical, mechanical, and biological properties. The incorporation of baghdadite contributed to making more porous scaffolds (over 40%) with larger surface area and micropore volumes. The produced composite scaffolds almost solved the low degradation problem of boron-doped hydroxyapatite through the exhibition of higher biodegradation rates, which matched the degradation rate appropriate for the gradual transfer of loads from implants to newly formed bone tissues. Besides higher bioactivity, enhanced cell proliferation, as well as higher osteogenic differentiation (in scaffolds with baghdadite weight greater than 10%), were observed in composite scaffolds due to both physical and chemical modifications that occurred in composite scaffolds. Although our composite scaffolds were slightly weaker than boron-doped hydroxyapatite, their compressive strengths were higher than almost all composite scaffolds made by baghdadite incorporation in the literature. In fact, boron-doped hydroxyapatite provided a base for baghdadite to show mechanical strength suitable for cancellous bone defect treatments. Eventually, our novel composite scaffolds converged the advantages of both components to satisfy the various requirements needed for bone tissue engineering applications and take us one step forward on the road to fabricating an ideal scaffold.

Nanoscale Chemical Surface Analyses of Recycled Powder for Direct Metal Powder Bed Fusion Ti-6Al-4V Root Analog Dental Implant: An X-ray Photoelectron Spectroscopy Study

Over the past couple of decades, additive manufacturing and the use of root-analogue-printed titanium dental implants have been developed. Not all powder particles are sintered into the final product during the additive manufacturing process. Reuse of the remaining powder could reduce the overall implant manufacturing cost. However, Ti-6Al-4V powder particles are affected by heat, mechanical factors, and oxidization during the powder bed fusion manufacturing process. Degradation of the powder may harm the final surface composition and decrease the biocompatibility and survival of the implant. The uncertainty of the recycled powder properties prevents implant fabrication facilities from reusing the powder. This study investigates the chemical composition of controlled, clean, and recycled titanium alloy powder and root-analogue implants (RAI) manufactured from these powders at three different depths. The change in titanium's quantity, oxidization state, and chemical composition in powder and RAI implants have been demonstrated and analyzed. While not identical, the surface chemical composition of the recycled powder implant and the implant manufactured from unused powder are similar. The results also indicate the presence of TiO₂ on all surfaces. Many studies confirmed that titanium dioxide on the implant's surface correlates with better osteointegration, reduced bacterial infection, and increased corrosion resistance. Considering economic and environmental aspects, surface chemical composition comparison of clean and reused powder is crucial for the future manufacturing of cost-effective and biocompatible implants.

Biocompatibility of a Zr-Based Metallic Glass Enabled by Additive Manufacturing

The present work explored the use of the selective laser melting (SLM) technique to develop a Zr-based bulk metallic glass (BMG) and investigate the influence of the process parameters on obtaining different levels of surface roughness. Moreover, the potential of the additively manufactured BMG Zr_59.3Cu_28.8Al_10.4Nb_1.5 (trade name AMLOY-ZR01) as an implant material was studied by evaluating the osteoblastic cell response to the alloy and its stability under simulated biological environments. The materials were characterized in terms of degree of crystallinity, surface roughness, and morphology, followed by a systematic investigation of the response of the MC3T3-E1 preosteoblastic cell line to the as-printed samples. The materials supported cell proliferation and differentiation of the preosteoblastic cells, with results comparable to the reference material Ti-6Al-4V. The surface microroughness and surface morphology (porous or groove-type laser tracks) investigated in this study did not have a significant effect on modulating the cell response. Ion release experiments showed a large increase in ion release under inflammatory conditions as compared to regular physiological conditions, which could be attributed to the increased local corrosion under inflammatory conditions. The findings in this work showed that the surface roughness of the additively manufactured BMG AMLOY-ZR01 can be tailored by controlling the laser power applied during the SLM process. The favorable cell response to the as-printed AMLOY-ZR01 represents of a significant advancement of the investigation of additively manufactured BMGs for orthopedic applications, while the results of the ion release study highlights the effect that inflammatory conditions could have on the degradation of the alloy.

Electrostatic Analysis of Bioactivity of Ti-6Al-4V Hydrophilic Surface with Laser Textured Micro-Square Convexes

At solid-liquid interfaces, charged particles within the electric double layer (EDL) are acted on by the electrostatic force, which may affect cell absorption and surface wettability. In this study, a model of the electrostatic force and surface tension of textured surfaces was presented. Then, the growth and adhesion of Murine osteoblasts (MC3T3-E1) cells on laser-ablated micro-square-textured Ti-6Al-4V surfaces were studied to demonstrate the use of a laser-processed texture to effectively improve bioactivity. Three different micro-square-textured hydrophilic surfaces, presenting lower contact angles of 19°, 22.5°, and 31.75° compared with that of a smooth surface (56.5°), were fabricated using a fiber-optic laser. Cellular morphology and initial cell attachment were analyzed by field emission scanning electron microscopy (SEM) and fluorescence microscopy, respectively. The results show that the electrostatic force not only made the textured surface more hydrophilic but also made the cells tend to adhere to the edges and corners of the protruding convexes. Cell morphology analysis also showed that cells would prefer to grow at the edges and corners of each micro-square convex protrusion. The laser-treated surfaces were more conducive to rapid cell growth and adhesion, and cells were preferentially attached on the hydrophilic-textured surfaces. Electrostatic force may be an important factor in effectively improving the bioactivity of Ti-6Al-4V surfaces, and the presence of more surface grooves would be more conducive to improving the bioactivity of cells.

The Influence of rhBMP-7 Associated with Nanometric Hydroxyapatite Coatings Titanium Implant on the Osseointegration: A Pre-Clinical Study

Background: Bioceramic nanometer coatings have been regarded as potential substitutes for plasma-sprayed hydroxyapatite coatings, and the association with bone morphogenetic protein (BMP) is an attempt to achieve faster osseointegration to hasten oral rehabilitation. Objective: This study aimed to investigate the effect of recombinant human bone morphogenetic protein-7 (rhBMP-7) on the osseointegration of titanium implants coated with a thin film surface of hydroxyapatite (HA). Methods: Two implants (n = 24) were placed in each white New Zealand rabbits’ femur (n = 6). Implants were placed in the right femur after standard instrumentation (A and B) and in the left femur after an over-instrumentation (C and D), preventing bone-implant contact. The distal implants were installed associated with rhBMP-7 (groups B [regular instrumentation] and D [over-instrumentation]) and, also, in the absence of without BMP (control groups A [regular instrumentation] and C [over-instrumentation]). After 4 weeks, the animals were euthanized. The bone blocks containing the implants were embedded in methyl methacrylate and sectioned parallel to the long axis of the implant, which were analyzed by image segmentation. The data were analyzed using a nonparametric statistical method. Results: We observed that Group A had a mean bone formation of 35.6% compared to Group B, which had 48.6% (p > 0.05). Moreover, this group showed 28.3% of connective tissue compared to Group A, with 39.3%. In the over-instrumented groups, rhBMP-7 (Group D) showed an enhanced and significant increase in bone formation when compared with the group without rhBMP-7 (Group C). Conclusion: We concluded that the association of rhBMP-7 to thin nanostructure HA-coated implants promoted greater new bone area than the same implants in the absence of rhBMP-7, mainly in cases of over-instrumented implant sites.

In-silico design and experimental validation of TiNbTaZrMoSn to assess accuracy of mechanical and biocompatibility predictive models

Numerical design of TiNbTaZrMoSn alloy preceded its manufacture and mechanical, physico-chemical and in vitro characterisation. The specifications of the alloy required a multi-objective optimisation including lower modulus of elasticity than c.p.Ti, high strength, stabilised β crystal structure with a low martensitic start temperature, a narrow solidification range and high biocompatibility. The results reveal that there was a good match between the bulk mechanical properties exhibited by the alloy experimentally and those predicted. Regarding surface properties, independent of roughness effects, the oxide thickness and surface zeta-potential, measured in biologically relevant electrolytes and at physiological pH, arose as important factors in osteoblastic activity (i.e., cell proliferation, measured via DNA, protein and metabolite content, and differentiation, via ALP levels), but not in cell adhesion and viability. The thinner oxide layer and lower absolute value of surface zeta-potential on the TiNbTaZrMoSn alloy explain its lesser osteogenic properties (i.e., inhibition of ALP activity) compared to the c.p. Ti. This study demonstrates that the numerical models to predict microstructure and bulk mechanical properties of β-Ti alloys are robust, but that the prediction of cellular bioactivity lags behind and still requires parameterisation to account for features such as oxide layer composition and thickness, electro-chemical properties and surface charge, and topography to optimise cell response in silico before committing to the costly manufacture and deployment of these alloys in regenerative medicine.

Preparation and In Vitro Analysis of Craniofacial Titanium Implants Surfaces Produced by Additive 3D Printing and Conventional Manufacturing

Study Design

Surface finish of titanium patient-specific craniofacial implants is known to affect their acceptability and durability and relevant literature still inconclusive on the best surface finishing protocol.

Objectives

This study investigated surface topography of three-dimensionally (3D) printed and conventionally manufactured craniofacial titanium implants following non-contact 3D laser profile-meter analysis.

Methods

Seven groups of titanium specimens (n = 10) were prepared and their surfaces were treated differently and included sole or combined treatment of mechanical polishing, gritting with 50 micron AL₂O₃, cold acid treatment using nitric acid for 20 hours (70% w/w), etching using acidic solution (69% nitric and 48% hydrofluoric acids) for 10 minutes and then electro-chemically anodized in another acidic solution (85% orthophosphoric and 98%sulphuric acid). Eighth group included specimens that were 3D printed. 3D micro-roughness parameters Sa, Sp, Sv, and Sz were determined (μm) for each specimen. Data was analyzed using one way ANOVA and Dunett T3 post-hoc tests (p < 0.05).

Results

There were statistically significant effects of surface finishing protocols (p < 0.05). Sa values were 2.72-13.75 and specimens which were electroplated or mechanically polished and acid treated were the smoothest (p < 0.05). Sp was in the range 9.07-43.56 as sandblasting significantly roughened surfaces (p < 0.05). The same inferior effect was evident for the Sv (p < 0.05). The Sz values were 19.46-107.05 and was the highest for sandblasted surfaces (p < 0.05) and the lowest for surfaces of electro-chemical treatment (p < 0.05).

Conclusion

Titanium surfaces are affected by the finishing procedure and electro-chemical treatment or mechanical polishing combined with acid treatment produced clinically-favorable smooth surfaces.

The Materiobiology of Silk: Exploring the Biophysical Influence of Silk Biomaterials on Directing Cellular Behaviors

Biophysical properties of the extracellular environment dynamically regulate cellular fates. In this review, we highlight silk, an indispensable polymeric biomaterial, owing to its unique mechanical properties, bioactive component sequestration, degradability, well-defined architectures, and biocompatibility that can regulate temporospatial biochemical and biophysical responses. We explore how the materiobiology of silks, both mulberry and non-mulberry based, affect cell behaviors including cell adhesion, cell proliferation, cell migration, and cell differentiation. Keeping in mind the novel biophysical properties of silk in film, fiber, or sponge forms, coupled with facile chemical decoration, and its ability to match functional requirements for specific tissues, we survey the influence of composition, mechanical properties, topography, and 3D geometry in unlocking the body's inherent regenerative potential.

Surface Modifications of Titanium Aluminium Vanadium Improve Biocompatibility and Osteogenic Differentiation Potential

Osteogenic cells are strongly influenced in their behaviour by the surface properties of orthopaedic implant materials. Mesenchymal stem and progenitor cells (MSPCs) migrate to the bone–implant interface, adhere to the material surface, proliferate and subsequently differentiate into osteoblasts, which are responsible for the formation of the bone matrix. Five surface topographies on titanium aluminium vanadium (TiAl₆V₄) were engineered to investigate biocompatibility and adhesion potential of human osteoblasts and the changes in osteogenic differentiation of MSPCs. Elemental analysis of TiAl₆V₄ discs coated with titanium nitride (TiN), silver (Ag), roughened surface, and pure titanium (cpTi) surface was analysed using energy-dispersive X-ray spectroscopy and scanning electron microscopy. In vitro cell viability, cytotoxicity, adhesion behaviour, and osteogenic differentiation potential were measured via CellTiter-Glo, CytoTox, ELISA, Luminex^® technology, and RT-PCR respectively. The Ag coating reduced the growth of osteoblasts, whereas the viability of MSPCs increased significantly. The roughened and the cpTi surface improved the viability of all cell types. The additive coatings of the TiAl₆V₄ alloy improved the adhesion of osteoblasts and MSPCs. With regard to the osteogenic differentiation potential, an enhanced effect has been demonstrated, especially in the case of roughened and cpTi coatings.

In vitro investigation of the cell compatibility and antibacterial properties of titanium treated with calcium and ozone

The purpose of this study was to evaluate the surface modification of calcium ions on roughened titanium as a surface treatment of dental implants for cell attachment, growth, and initial bacterial adhesion. When a surface-roughened, pure titanium disk was immersed in a calcium chloride solution (100 mM) containing 20 ppm ozone for 24 h at 25ºC, calcium was detected on the surface by X-ray photoelectron spectroscopy. The calcium-modified, roughened titanium disk had a significantly greater concentration of the initially adhered cells as well as cells cultured over 7 days compared with titanium disks without surface modification. Furthermore, the initial bacterial adhesion on the calcium-ozone treated titanium disk was statistically less than on a pure titanium disk or titanium disk treated without ozone. Dissolved ozone was useful for modifying the surface of roughened titanium with calcium ions and the surface modification may be applicable for dental implants.

Development of tantalum with highly hydrophilic surface and antimicrobial properties obtained by micro-arc oxidation process

Tantalum (Ta) and its application in biomaterials has been attracting more and more attention recently. It can be considered as a material for hard tissue implants. This study focuses on antimicrobial and surface characterization of micro-arc oxidized (MAO) nanocrystalline Ta compared with its microcrystalline equivalent. For the purposes of the investigation, x-ray diffractometry (XRD), scanning electron microscopy (SEM), atomic force microscopy (AFM), wetting analysis, optical profilometry, corrosion resistance measurement, and antimicrobial tests were performed. Nanocrystalline Ta was fabricated using high-energy ball milling (HEBM) and pulse plasma sintering (PPS). The MAO process done at 250 V results in the formation of a porous oxide surface. An XRD analysis confirmed the presence of a Ta₂ O₅ oxide layer. Based on the SEM pictures, the obtained oxide layer was approximately 3-4 μm thick for nanocrystalline Ta substrate. For microcrystalline Ta, the oxide layer was thinner, in the range of 0.3-0.6 μm. The analysis of polarization curves showed a significant improvement of corrosion resistance for MAO nanocrystalline Ta (2.62 × 10^-8 A/cm² ) versus not oxidized nanocrystalline Ta (1.20 × 10^-5 A/cm² ). The surface roughness of MAO nanocrystalline Ta proved to be several times higher than that of unoxidized Ta. Wetting analysis showed that the oxide layer on the nanocrystalline substrate is hydrophilic. This research provides detailed information about MAO microcrystalline and MAO nanocrystalline Ta antimicrobial activity against Staphylococcus aureus and Pseudomonas aeruginosa. A significant decrease of S. aureus for MAO nanocrystalline Ta (control 10,435 ± 981 vs. sample 3,453 ± 130) was noticed. No significant difference was noticed for MAO microcrystalline and nanocrystalline Ta tested for P. aeruginosa.

Cobalt Chromium Molybdenum Surface Modifications Alter the Osteogenic Differentiation Potential of Human Mesenchymal Stem Cells

Surface roughness on orthopedic implant materials has been shown to be highly influential on the behavior of osteogenic cells. Mesenchymal stem and progenitor cells (MSPCs) migrate to the interface, adhere, proliferate, and differentiate into osteoblasts, which subsequently form bone matrix. Modifications of the implant surfaces should accelerate this process and improve biocompatibility. In this study, five surface topographies on cobalt chromium molybdenum (CoCrMo) were engineered to examine the influence on MSPCs. Scanning electron microscopy revealed significant differences in the morphology of untreated CoCrMo discs in comparison with CoCrMo with a titanium nitride (TiN) coating, polished and porous coated CoCrMo surfaces, and CoCrMo with a pure titanium (cpTi) coating. Elemental analysis was performed using energy-dispersive X-ray spectroscopy (EDX). Human primary MSPCs were expanded from tissue samples of spongiosa bone and characterized according to the criteria of the International Society for Cellular Therapy. The characteristic phenotype of MSPC was confirmed by flow cytometry and multilineage differentiation. Alcaline phosphatase and osteopontin expression increased significantly in all groups about 5-fold and 10-fold, respectively, in comparison to the undifferentiated controls. The porous coated surface showed a reduced expression of osteogenic markers. Due to the osteogenic differentiation, the expression of integrin α5β1, which is particularly important for cell-material contact, increased 4–7-fold. In the dynamic process of bone biology, MSPCs cultured and differentiated on cpTi, showed significant upregulation of IL6 and leptin.

Surface roughness of titanium disks influences the adhesion, proliferation and differentiation of osteogenic properties derived from human

PURPOSE

The aim of this study was to investigate the response of osteogenic cell lineage and gingival fibroblastic cells to different surface treatments of grade IV commercially pure Titanium (cpTi) disks.

MATERIAL AND METHODS

Grade IV cpTi disks with different surfaces were produced: machined (M), sandblasting (B), sandblasting and acid subtraction (NP), and hydrophilic treatment (ACQ). Surface microtopography characteristics and chemical composition were investigated by scanning electron microscopy (SEM) and energy dispersive x-ray spectrometry (EDS). Adhesion and proliferation of SC-EHAD (human surgically-created early healing alveolar defects) and HGF-1 (human gingival fibroblasts) on Ti disks were investigated at 24 and 48 h, and osteogenic differentiation and mineralization were evaluated by assessing alkaline phosphatase (ALP) activity and alizarin red staining, respectively.

RESULTS

No significant differences were found among the various surface treatments for all surface roughness parameters, except for skewness of the assessed profile (Rsk) favoring M (p = 0.035 ANOVA). M disks showed a slightly higher (p > 0.05; Kruskal-Wallis/Dunn) adhesion of HGF-1 (89.43 ± 9.13%) than SC-EHAD cells (57.11 ± 17.72%). ACQ showed a significantly higher percentage of SC-EHAD (100%) than HGF-1 (69.67 ± 13.97%) cells adhered at 24 h. SC-EHAD cells expressed increased ALP activity in osteogenic medium at M (213%) and NP (235.04%) surfaces, but higher mineralization activity on ACQ (54.94 ± 4.80%) at 14 days.

CONCLUSION

These findings suggest that surface treatment influences the chemical composition and the adhesion and differentiation of osteogenic cells in vitro.

CLINICAL RELEVANCE

Hydrophilic surface treatment of grade IV cpTi disks influences osteogenic cell adhesion and differentiation, which might enhance osseointegration.

Osseointegration around dental implants biofunctionalized with TGFβ-1 inhibitor peptides: an in vivo study in beagle dogs

The aim of this study was to evaluate the effect of biofunctionalization with two TGF-β1 inhibitor peptides, P17 and P144, on osseointegration of CP-Ti dental implants. A total of 36 implants (VEGA, Klockner®) with 3.5 × 8 mm internal connection were used in this study, divided in three groups: (1) control group (n = 12), (2) implants which surfaces were biofunctionalized with P17 peptide inhibitor (n = 12), (3) implants with surfaces biofunctionalized by P144 peptide (n = 12). Three implants, one from each group, were inserted in both hemimandibles of 6 beagle dogs, 2 months after tooth extraction. Two animals were sacrificed at 2, 4 and 8 weeks post implant insertion, respectively. The samples were analyzed by Backscattering Scanning Electron Microscopy (BS-SEM) and histological analysis. Histomorphometric analysis of bone to implant contact (BIC), peri-implant bone fraction (BF) and interthread bone (IB) were carried out. Bone formation around implants measured by quantitative analysis, BS-SEM, was significantly higher in the P17-biofunctionalized implants, 4 and 8 weeks after the implantation. Histomorphometric analysis of BIC, BF and IB showed higher values in the P17-biofunctionalized group at initial stages of healing (2 weeks) and early osseointegration both at 4 and 8 weeks. For P144 biofunctionalized implants, the histomorphometric values obtained are also higher than control group. Accordingly, better results in the experimental groups were proven both by the quantitative and the qualitative analysis. Surface biofunctionalization with TGF-β1 inhibitor peptides, P17 and P144, resulted in better quantitative and qualitative parameters relative to implant osseointegration.

Addition of Sn to TiNb alloys to improve mechanical performance and surface properties conducive to enhanced cell activity

Titanium (Ti) alloys with Niobium (Nb) and Tin (Sn) were prepared in order to conduct a systematic study on the bulk and surface properties of as-cast c.p.Ti, binary Ti-40Nb and Ti-10Sn, and ternary Ti-10Nb-5Sn (at.%) to ascertain whether Sn content can be used as an enhancer for cell activity. From a metallurgy viewpoint, a range of binary and ternary alloys displaying distinctive Ti phases (i.e. β, α', α") were achieved at room temperature. Their surface (oxide thickness and composition, roughness, contact angle) and bulk (compressive stiffness, strength, elongation, microhardness, electrical resistance) features were characterised. The same surface roughness was imparted on all the alloys, therefore substrate-cell interactions were evaluated independently from this variable. The physico-mechanical properties of the ternary alloy presented the highest strength to stiffness ratio and thereby proved the most suitable for load-bearing orthopaedic applications. From a cellular response viewpoint, their cytotoxicity, ability to adsorb proteins, to support cell growth and to promote proliferation were studied. Metabolic activity using a mouse model was monitored for a period of 12 days to elucidate the mechanism behind an enhanced proliferation rate observed in the Sn-containing alloys. It was hypothesised that the complex passivating surface oxide layer and the bulk inhomogeneity with two dominant Ti phases were responsible for this phenomenon.

Multi-Scale Surface Treatments of Titanium Implants for Rapid Osseointegration: A Review

The propose of this review was to summarize the advances in multi-scale surface technology of titanium implants to accelerate the osseointegration process. The several multi-scaled methods used for improving wettability, roughness, and bioactivity of implant surfaces are reviewed. In addition, macro-scale methods (e.g., 3D printing (3DP) and laser surface texturing (LST)), micro-scale (e.g., grit-blasting, acid-etching, and Sand-blasted, Large-grit, and Acid-etching (SLA)) and nano-scale methods (e.g., plasma-spraying and anodization) are also discussed, and these surfaces are known to have favorable properties in clinical applications. Functionalized coatings with organic and non-organic loadings suggest good prospects for the future of modern biotechnology. Nevertheless, because of high cost and low clinical validation, these partial coatings have not been commercially available so far. A large number of in vitro and in vivo investigations are necessary in order to obtain in-depth exploration about the efficiency of functional implant surfaces. The prospective titanium implants should possess the optimum chemistry, bionic characteristics, and standardized modern topographies to achieve rapid osseointegration.

The Impact of EBM-Manufactured Ti6Al4V ELI Alloy Surface Modifications on Cytotoxicity toward Eukaryotic Cells and Microbial Biofilm Formation

Electron beam melting (EBM) is an additive manufacturing technique, which allows forming customized implants that perfectly fit the loss of the anatomical structure of bone. Implantation efficiency depends not only on the implant's functional or mechanical properties but also on its surface properties, which are of great importance with regard to such biological processes as bone regeneration or microbial contamination. This work presents the impact of surface modifications (mechanical polishing, sandblasting, and acid-polishing) of EBM-produced Ti6Al4V ELI implants on essential biological parameters. These include wettability, cytotoxicity toward fibroblast and osteoblast cell line, and ability to form biofilm by Staphylococcus aureus, Pseudomonas aeruginosa, and Candida albicans. Obtained results indicated that all prepared surfaces exhibited hydrophilic character and the highest changes of wettability were obtained by chemical modification. All implants displayed no cytotoxicity against osteoblast and fibroblast cell lines regardless of the modification type. In turn, the quantitative microbiological tests and visualization of microbial biofilm by means of electron microscopy showed that type of implant's modification correlated with the species-specific ability of microbes to form biofilm on it. Thus, the results of the presented study confirm the relationship between such technological aspects as surface modification and biological properties. The provided data are useful with regard to applications of the EBM technology and present a significant step towards personalized, customized implantology practice.

Effect of ultrasonic micro-arc oxidation on the antibacterial properties and cell biocompatibility of Ti-Cu alloy for biomedical application

In order to improve antibacterial properties and cell biocompatibility of Ti-Cu alloy, an ultrasonic micro-arc oxidation (UMAO) has been applied to Ti-Cu alloy. The corrosion resistance, antibacterial activity and cell compatibility of Ti-Cu alloy before and after UMAO were studied in detail by means of electrochemical test, plate count method and CCK-8 test scanning electron microscopy (SEM) technology to evaluate the application possibilities of UMAO as a surface bio-modification method for Ti-Cu alloy. The surface microstructure characterisation showed that a typical porous coating with a pore diameter of 3-8 μm and a thickness of 5-15 μm was formed on the surface of the Ti-Cu alloy, which significantly improved the surface roughness and hydrophilicity. The plate count method demonstrated that UMAO coatings on Ti-Cu alloy showed strong antibacterial activity (≥99%) against Staphylococcus aureus (S. aureus) even after being immersed in a physiological saline for up to 20 days, indicating that UMAO-treated Ti-Cu alloy had very strong long-term antibacterial properties. It is believed that the strong long-term antimicrobial properties of Ti-Cu-UMAO samples were mainly due to the formation of Cu₂O and CuO in UMAO coatings. The results of cell compatibility evaluation showed that UMAO treatment did not bring about cytotoxicity but improved the early adhesion of MC3T3 cell.

CoCrMo surface modifications affect biocompatibility, adhesion, and inflammation in human osteoblasts

In this study, different surface modifications were performed on a Cobalt-Chrome-Molybdenum (CoCrMo) alloy and the effects on cell viability and cytotoxicity as well as the adhesion potential of human osteoblasts (hFOB) and their inflammation reaction were investigated in vitro. CoCrMo discs were coated with TiN, with polished and porous coated surfaces, or with pure titanum (cpTi) surfaces and examined by Scanning Electron Microscopy to evaluate surface modifications. In vitro cell viability, adhesion behaviour, and expression of inflammation markers of hFOB human osteoblasts were measured via CellTiter-Glo, CytoTox, ELISA, and RT-PCR respectively. All results were compared to CoCrMo without surface modifications. The biocompatibility data showed high compatibility for the TiN hard coatings. Likewise, the porous surface coating increased cell viability significantly, compared to an untreated CoCrMo alloy. None of the investigated materials influenced cytotoxicity. Different surface modifications did not influence expression of fibronectin, although TiN, porous surface coatings and polished surfaces showed highly significant reductions in integrin subunit expression. In addition to the regulation of adhesion potential these three surfaces stimulated an anti-inflammatory response by osteocytes. Improved biocompatibility and adhesion properties may contribute to better osteointegration of prosthetics.

Aligned multi-walled carbon nanotubes with nanohydroxyapatite in a 3D printed polycaprolactone scaffold stimulates osteogenic differentiation

The development of highly biomimetic scaffolds in terms of composition and structures, to repair or replace damaged bone tissues, is particularly relevant for tissue engineering. This paper investigates a 3D printed porous scaffold containing aligned multi-walled carbon nanotubes (MWCNTs) and nano-hydroxyapatite (nHA), mimicking the natural bone tissue from the nanoscale to macroscale level. MWCNTs with similar dimensions as collagen fibres are coupled with nHA and mixed within a polycaprolactone (PCL) matrix to produce scaffolds using a screw-assisted extrusion-based additive manufacturing system. Scaffolds with different material compositions were extensively characterised from morphological, mechanical and biological points of views. Transmission electron microscopy and polarised Raman spectroscopy confirm the presence of aligned MWCNTs within the printed filaments. The PCL/HA/MWCNTs scaffold are similar to the nanostructure of native bone and shows overall increased mechanical properties, cell proliferation, osteogenic differentiation and scaffold mineralisation, indicating a promising approach for bone tissue regeneration.

Enhanced Osseointegration of Titanium Alloy Implants with Laser Microgrooved Surfaces and Graphene Oxide Coating

Rapid and effective osseointegration, as a critical factor in affecting the success rate of titanium (Ti) implants in orthopedic applications, is significantly affected by their surface microstructure and chemical composition. In this work, surface microgrooved Ti-6Al-4V alloys with graphene oxide coating (Ti-G-GO) were fabricated by a combination of laser processing and chemical assembly techniques. The osteogenic capability in vitro and new bone formation in vivo of the implants were systematically investigated, and biomechanical pull-out tests of the screws were also performed. First, in vitro studies indicated that the optimal microgroove width of the titanium alloy surface was 45 μm (Ti-G), and the optimum GO concentration was 1 mg/mL. Furthermore, the effects of the surface microstructure and GO coating on the in vitro bioactivity were investigated through culturing bone marrow mesenchymal stem cells (BMSCs) on the surface of titanium alloy plates. The results showed that the BMSCs cultured on the Ti-G-GO group exhibited the best adhesion, proliferation, and differentiation, compared with that on the Ti-G and Ti groups. Micro-computed tomography evaluation, histological analysis, and pull-out testing demonstrated that both Ti-G and Ti-G-GO implants had the higher osseointegration than the untreated Ti implant. Moreover, the osteogenic capability of the Ti-G-GO group appeared to be superior to that of the Ti-G group, which could be attributed to the improvement of surface wettability and apatite formation by the GO coatings. These results suggest that the combination of the microgroove structure and GO coatings exhibits considerable potential for enhancing the surface bioactivation of materials, and the combination modification is expected to be used on engineered titanium alloy surfaces to enhance osseointegration for orthopedic applications.

Corrosion behavior, in vitro and in vivo biocompatibility of a newly developed Ti-16Nb-3Mo-1Sn superelastic alloy

The biocompatibility of a recently developed Ni-free Ti-16Nb-3Mo-1Sn (at.%) superelastic alloy was investigated both in vitro and in vivo. In addition, static water contact angle (WCA) and electrochemical tests were carried out. Commercial purity Ti (cp-Ti), which is already being used as a clinical material, was used as the control material. The alloy showed a stable corrosion behavior similar to that of the cp-Ti. The WCA measurements showed that the alloy exhibited hydrophilic properties that contributed to cell attachment to implants, as evident by the cytocompatibility tests. According to the in vivo implantation tests conducted on 30 adult BALB/c rats for periods up to 12 weeks, the tissue reaction around the implants was similar for both the cp-Ti and the alloy, and no significant difference was found in almost all parameters analyzed. Due to its stable superelastic properties accompanied with excellent biocompatibility and high corrosion resistance, we believe that this alloy is considered as a promising substitute for the biomedical materials containing Ni or other toxic elements.

Accelerated discovery and mechanical property characterization of bioresorbable amorphous alloys in the Mg-Zn-Ca and the Fe-Mg-Zn systems using high-throughput methods

Ternary amorphous alloys in the magnesium (Mg)-zinc (Zn)-calcium (Ca) and the iron (Fe)-Mg-Zn systems are promising candidates for use in bioresorbable implants and devices. The optimal alloy compositions for biomedical applications should be chosen from a large variety of available alloys with best combination of mechanical properties (modulus, strength, hardness) and biological response (in situ degradation rates, cell adhesion and proliferation). As a first step towards establishing a database designed to enable such targeted material selection, amorphous alloy composition libraries were fabricated employing a combinatorial magnetron sputtering approach where Mg, Zn, and Ca/Fe are co-deposited from separate sources onto a silicon wafer substrate. Composition analysis using energy dispersive X-ray spectroscopy documented a composition range of ∼15-85 at% Mg, ∼6-55 at% Zn, and ∼5-60 at% Ca for the Mg-Zn-Ca library and ∼26-84 at% Mg, ∼10-61 at% Zn, and ∼7-55 at% Fe for the Fe-Mg-Zn library. X-ray diffraction measurements established that amorphous alloys (i.e., glasses) form in almost the entire range of composition at the high cooling rates during sputtering for both alloy libraries. Finally, the effective material modulus, the Oliver-Pharr hardness, and the yield strength values obtained using nanoindentation reveal a wide range of mechanical properties within both systems.

In vitro bioactivity of laser surface-treated Ti6Al4V alloy

The effects of lasing parameters on the precipitation of hydroxyapatite (HA) on the commercial Ti6Al4V alloy in simulated body fluid (SBF) were investigated. Ti6Al4V plates were polished and ultrasonically cleaned in acetone and ethyl alcohol, respectively. The specimen surfaces were treated with Er:YAG laser using super short pulse (SSP, 50 μs) and very short pulse (VSP, 100 μs) modes. Surface roughness was measured before and after laser treatment. The specimens were immersed in simulated body fluid (SBF) for 1, 3, and 7 days and, then the amount of Ca and P precipitation on specimens was determined using SEM/EDS analysis. An average roughness varying between 0.19 and 0.81 μm in surface roughness was detected in all laser-treated specimens depending on the lasing parameters. The highest surface roughness and Ca precipitation were found in VSP group (20 Hz and 5 W). Laser treatment of specimen surfaces has dramatically increased the HA precipitation due to the increasing surface roughness. It is also concluded that the immersion time was effective on the HA precipitation as well.

Multilayer fabrication of unobtrusive poly(dimethylsiloxane) nanobrush for tunable cell adhesion

Precise modulation of polymer brush in its thickness and grafting density can cause unexpected cell behaviors and regulated bioactivities. Herein, a nanoscale poly(dimethylsiloxane) (PDMS) brush was employed to use as a controllable material for cell adhesion. Facile fabrication of ultrathin monolayer PDMS nanobrush on an underlying substrate facilitated regaining cell adhesion through long-range cell attractive forces such as the van der Waals forces. We showed that cell adhesion is diminished by increasing the number of nanobrush layers, causing a gradual decrease of the effectiveness of the long-range force. The result demonstrates that ultrathin PDMS nanobrush can either promote or inhibit cell adhesion, which is required for various biomedical fields such as tissue-engineering, anti-fouling coating, and implantable biomaterials and sensors.

Oxide thin films as bioactive coatings

Growth and survival of biological cells (eukaryotes and prokaryotes) on artificial environments often depend on their interactions with the specific surface. Various organic materials can be coated on substrates to assist cells' adhesion and other subsequent cellular processes. However, these coatings are expensive, degrade over short time period, and may even interfere with the cells' signaling processes. Therefore, the use of inorganic surfaces in order to control cellular interactions is of scientific importance from fundamental and application perspectives. Among inorganic materials, oxide thin films have received considerable attention. Thin films of oxides have the advantage of tailoring the surfaces for cellular interactions while using a negligible amount of the oxide material. Here, we review the lesser known application of inorganic oxide coatings as biocompatible and implantable platforms for different purposes, such as biofilm inhibition, cell culture and implant enhancements.

A Novel Image Probing System for Precise Quantification of Angiogenesis

The rapid development of clinical diagnostic imaging technology, in tandem with medical and angiogenesis research, has led to some major advances in healthcare. The chorioallantoic membrane assay is commonly used for studying normal angiogenesis as well as putative angiogenic and antiangiogenic substances. Despite the progress, it is generally recognized that a major problem is the lack of a suitable quantitative bioassay for angiogenesis. Image probing is a novel solution to this problem, which, together with its associated discipline of evaluating angiogenesis, is showing great potential not only for accurate measurement of even very small blood vessels but also for detailed three-dimensional quantification of blood vessels and surface characterization. This technique could be a helpful tool for quantification in angiogenesis research.

Effect of employing ultrasonic waves during pulse electrochemical deposition on the characteristics and biocompatibility of calcium phosphate coatings

In the present work, we investigated the effect of employing ultrasonic waves during pulse electrochemical deposition on surface topography, chemical composition and biocompatibility of calcium phosphate (Ca-P) coatings. The SEM and 3D AFM images showed that the anodized titanium surface was covered with the uniform and refined size of plate-like Ca-P crystals, when the ultrasonic treatment of the electrolyte with power of 60 W was carried out during deposition. In contrast, for the Ca-P; 0 W coating applied under only the magnetic stirring of the electrolyte, the microstructure was non-uniform and some Ca-P crystals with the larger size were randomly observed in different regions, causing a rougher surface. The FTIR results also revealed that employing the ultrasound increases the deposition of a coating involved in only the most stable Ca-P phase of carbonated hydroxyapatite (CHA). However, in the absence of ultrasound, besides the prominent phase of CHA, some less stable Ca-P phases like octa calcium phosphate (OCP) and brushite were also formed in the Ca-P; 0 W coating. The Ca-P; 60 W coating showed the higher ability for apatite biomineralization after a 7-day immersion in the simulated body fluid (SBF). This coating also provided a better surface for the cellular activity, as compared to the Ca-P; 0 W coating.

Effect of the Heat-Treated Ti6Al4V Alloy on the Fibroblastic Cell Response

Two heat treatments were carried out below (Ti6Al4V₈₀₀) and above (Ti6Al4V₁₀₅₀) Ti6Al4V beta-phase transformation temperature (980 °C), with the purpose of studying the effect of microstructure on the adhesion and proliferation of fibroblast cells, as well as their electrochemical behavior. These alloys were seeded with 10,000 L929 fibroblast cells and immersed for 7 days in the cell culture at 37 °C, pH 7.40, 5% CO₂ and 100% relative humidity. Cell adhesion was characterized by Scanning Electron Microscopy (SEM) and Electrochemical Impedance Spectroscopy (EIS) techniques. Polygonal and elongated cell morphology was observed independent of Ti6Al4V microstructure. Besides, C, O, P, S, Na and Cl signals were detected by Energy Dispersive X-Ray Spectroscopy (EDX), associated with the synthesis of organic compounds excreted by the cells, including protein adsorption from the medium. In certain areas on Ti6Al4V and Ti6Al4V₈₀₀ alloys, cells were agglomerated (island type), likely related to the globular microstructure; meanwhile, larger cellular coverage is shown for Ti6Al4V₁₀₅₀ alloy, forming more than one layer on the surface, where only Ca was recorded. Impedance diagrams showed a similar passive behavior for the different Ti6Al4V alloys, mainly due to TiO₂ overlaying the contribution of the organic compounds excreted by fibroblast cells.

Surface Mechanoengineering of a Zr-Based Bulk Metallic Glass via Ar-Nanobubble Doping To Probe Cell Sensitivity to Rigid Materials

In this study, a new materials platform, utilizing the amorphous microstructure of bulk metallic glasses (BMGs) and the versatility of ion implantation, was developed for the fundamental investigation of cell responses to substrate-rigidity variations in the gigapascal modulus range, which was previously unattainable with polymeric materials. The surface rigidity of a Zr-Al-Ni-Cu-Y BMG was modulated with low-energy Ar-ion implantation because of the impartment of Ar nanobubbles into the amorphous matrix. Surface softening was achieved due to the formation of nanobubble-doped transitional zones in the Zr-based BMG substrate. Bone-forming cell studies on this newly designed platform demonstrated that mechanical cues, accompanied by the potential effects of other surface properties (i.e., roughness, morphology, and chemistry), contributed to modulating cell behaviors. Cell adhesion and actin filaments were found to be less established on less stiff surfaces, especially on the surface with an elastic modulus of 51 GPa. Cell growth appeared to be affected by surface-mechanical properties. A lower stiffness was generally related to a higher growth rate. Findings in this study broadened our fundamental understanding concerning the mechanosensing of bone cells on stiff substrates. It also suggests that surface mechanoengineering of metallic materials could be a potential strategy to promote osseointegration of such materials for bone-implant applications. Further investigations are proposed to fine-tune the ion implantation variables in order to further distinguish the surface-mechanical effect on bone-forming cell activities from the contributions of other surface properties.

Osteoblastic cell behaviour on modified titanium surfaces

INTRODUCTION

The surfaces of endoosseous dental implants have been subjected to numerous modifications in order to create a surface which can provide rapid bone healing and fast implant loading. Each modification has involved changes to the chemical composition and topography of the surfaces which have resulted in various biological reactions to the implanted material.

AIM

The aim of this study was to evaluate the surface topography and chemistry of various modified titanium surfaces: (1) machined surface (MA), (2) alumina-blasted (Al2O3), (3) alumina-blasted and acid-etched (Al2O3 DE), (4) hydroxyapatite/tricalcium phosphate grit-blasted (HA/TCP) and (5) hydroxyapatite/tricalcium phosphate grit-blasted and acid-etched (HA/TCP DE) and to analyse the effects of surface roughness, and chemical composition on human osteoblast vitality, differentiation, morphology and orientation.

MATERIALS AND METHODS

The modified surfaces were subjected to topographic analysis using Scanning Electron Microscopy (SEM), optical profilometry, roughness analysis and chemical composition evaluation using Energy Dispersion Spectroscopy (EDS) analysis. The biological effects of the titanium modifications was analysed using human osteoblasts cell culture where the cell morphology, vitality (MTS assay) and differentiation (ALP activity) was analysed.

RESULTS

The machined surfaces were classified as anisotropic, smooth and composed of titanium and oxygen. The blasted surface samples along with the blasted and etched samples were found to be isotropic and rough. The grit-blasting procedure resulted in the incorporation of components from the blasting material. In the case of the blasted and etched samples, etching decreased the surface development as indicated by the Sdr and also reduced the amount of chemical compounds incorporated into the surfaces during the blasting procedure. The attached NHOst cells, proliferated the surfaces. With regard to the MA samples, the cells spread close to the titanium surface, with expanded cytoplasmic extensions and lamelipodia and were oriented in line with the groves left after machining. On the rough substrates, cells were less dispersed and exhibited numerous cytoplasmic extensions, filopodia and interconnections, they were not oriented with respect to the surfaces features. The cell viability of all samples except for Al2O3 decreased after the first day of culture. For all Al2O3, Al2O3 DE and HA samples the viability increased with culture time after an initial reduction. At the end of the culture period the ALP activity was slightly greater on Al2O3 and HA samples compared to the control with the HA DE sample having the same activity as the control. The Al2O3, HA and HA DE ALP samples showed comparable activity and were statistically different from MA and Al2O3 DE samples.

CONCLUSIONS

In this study, variously treated titanium surfaces were correlated with osteoblastic cell viability, morphology and differentiation in comparison with the plastic and smooth titanium. All examined surfaces were found to be biocompatible. Favourable cell reactions were observed for Al2O3 and HA blasted surfaces. The surface roughness patterns influenced the growth orientation while the surface topography influenced osteoblast morphology. Further animal studies are necessary to compare the in-vivo effect on osseointegration of these modified titanium surfaces.

Modification of titanium alloys surface properties by plasma electrolytic oxidation (PEO) and influence on biological response

Surface characteristics can mediate biological interaction improving or affecting the tissue integration after implantation of a biomaterial. Features such as topography, wettability, surface energy and chemistry can be key determinants for interactions between cells and materials. Plasma electrolytic oxidation (PEO) is a technique used to control this kind of parameters by the addition of chemical species and the production of different morphologies on the surfaces of titanium and its alloys. With the purpose to improve the biological response, surfaces of c.p titanium and Ti6Al4V were modified by using PEO. Different electrolytes, voltages, current densities and anodizing times were tested in order to obtain surfaces with different characteristics. The obtained materials were characterized by different techniques such as X-ray diffraction (XRD), scanning electron microscopy (SEM) and glow discharge optical emission spectroscopy (GDOES). Wettability of the obtained surfaces were measured and the corresponding surface energies were calculated. Superhydrophilic surfaces with contact angles of about 0 degrees were obtained without any other treatment but PEO and this condition in some cases remains stable after several weeks of anodizing; crystal phase composition (anatase-rutile) of the anodic surface appears to be critical for obtaining this property. Finally, in order to verify the biological effect of these surfaces, osteoblast were seeded on the samples. It was found that cell behavior improves as SFE (surface free energy) and coating porosity increases whereas it is affected negatively by roughness. Techniques for surface modification allow changes in the coatings such as surface energy, roughness and porosity. As a consequence of this, biological response can be altered. In this paper, surfaces of c.p Ti and Ti6Al4V were modified by using plasma electrolytic oxidation (PEO) in order to accelerate the cell adhesion process.

Bio-functionalizing heterogeneous phase activated titanium by multiphoton ionization energy mechanism to harmonize cell proliferative behavior

Cellular interactions are regulated by various mechanical, physical and chemical factors that are either introduced to or are pre-existing in their local microenvironments. These factors include geometric confinement, cell-substrate interactions and cell-cell contacts. The systematic elucidation of these dictating mechanisms is crucial for fundamental understanding of regenerative medicine and for designing biomedical devices. Here, we have developed an elegant multi-photon ionization based mechanism, which accomplishes selective surface bio-functionalization of native titanium substrates, to achieve stable cellular confinements. In particular, we applied selective titanium phase activation for cellular confinement of mouse fibroblasts and osteoblast cells in an effort to examine their directionality and proliferative behavior under confinement. The experimental results suggest, both mouse fibroblasts and osteoblasts can be manipulated, guided and aligned along an induced orientation by selective hongquiite phase activation. The cell viability of both fibroblast and osteoblast cells were observed through fluorescent assays and SEM techniques. The phase activated surface fabricated influenced both nuclei and actin cytoskeletal re-arrangement of cell structures.

Copper as an alternative antimicrobial coating for implants - An in vitro study

AIM

To investigate osteoconductive and antimicrobial properties of a titanium-copper-nitride (TiCuN) film and an additional BONIT^® coating on titanium substrates.

METHODS

For micro-structuring, the surface of titanium test samples was modified by titanium plasma spray (TPS). On the TPS-coated samples, the TiCuN layer was deposited by physical vapor deposition. The BONIT^® layer was coated electrochemically. The concentration of copper ions released from TiCuN films was measured by atomic absorption spectrometry. MG-63 osteoblasts on TiCuN and BONIT^® were analyzed for cell adhesion, viability and spreading. In parallel, Staphylococcus epidermidis (S. epidermidis) were cultivated on the samples and planktonic and biofilm-bound bacteria were quantified by counting of the colony-forming units.

RESULTS

Field emission scanning electron microscopy (FESEM) revealed rough surfaces for TPS and TiCuN and a special crystalline surface structure on TiCuN + BONIT^®. TiCuN released high amounts of copper quickly within 24 h. These release dynamics were accompanied by complete growth inhibition of bacteria and after 2 d, no planktonic or adherent S. epidermidis were found on these samples. On the other hand viability of MG-63 cells was impaired during direct cultivation on the samples within 24 h. However, high cell colonization could be found after a 24 h pre-incubation step in cell culture medium simulating the in vivo dynamics closer. On pre-incubated TiCuN, the osteoblasts span the ridges and demonstrate a flattened, well-spread phenotype. The additional BONIT^®coating reduced the copper release of the TiCuN layer significantly and showed a positive effect on the initial cell adhesion.

CONCLUSION

The TiCuNcoating inhibits the formation of bacterial biofilms on orthopedic implants by influencing the “race for the surface” to the advantage of osteoblasts.

Corrosion and surface modification on biocompatible metals: A review

Corrosion prevention in biomaterials has become crucial particularly to overcome inflammation and allergic reactions caused by the biomaterials' implants towards the human body. When these metal implants contacted with fluidic environments such as bloodstream and tissue of the body, most of them became mutually highly antagonistic and subsequently promotes corrosion. Biocompatible implants are typically made up of metallic, ceramic, composite and polymers. The present paper specifically focuses on biocompatible metals which favorably used as implants such as 316L stainless steel, cobalt-chromium-molybdenum, pure titanium and titanium-based alloys. This article also takes a close look at the effect of corrosion towards the implant and human body and the mechanism to improve it. Due to this corrosion delinquent, several surface modification techniques have been used to improve the corrosion behavior of biocompatible metals such as deposition of the coating, development of passivation oxide layer and ion beam surface modification. Apart from that, surface texturing methods such as plasma spraying, chemical etching, blasting, electropolishing, and laser treatment which used to improve corrosion behavior are also discussed in detail. Introduction of surface modifications to biocompatible metals is considered as a "best solution" so far to enhanced corrosion resistance performance; besides achieving superior biocompatibility and promoting osseointegration of biocompatible metals and alloys.

Inkjet printed periodical micropatterns made of inert alumina ceramics induce contact guidance and stimulate osteogenic differentiation of mesenchymal stromal cells

Bioinert high performance ceramics exhibit detrimental features for implant components with direct bone contact because of their low osseointegrating capability. We hypothesized that periodical microstructures made of inert alumina ceramics can influence the osteogenic differentiation of human mesenchymal stromal cells (hMSC). In this study, we manufactured pillared arrays made of alumina ceramics with periodicities as low as 100μm and pillar heights of 40μm employing direct inkjet printing (DIP) technique. The response of hMSC to the microstructured surfaces was monitored by measuring cell morphology, viability and formation of focal adhesion complexes. Osteogenic differentiation of hMSCs was investigated by alkaline phosphatase activity, mineralization assays and expression analysis of respective markers. We demonstrated that MSCs react to the pillars with contact guidance. Subsequently, cells grow onto and form connections between the microstructures, and at the same time are directly attached to the pillars as shown by focal adhesion stainings. Cells build up tissue-like constructs with heights up to the micropillars resulting in increased cell viability and osteogenic differentiating properties. We conclude that periodical micropatterns on the micrometer scale made of inert alumina ceramics can mediate focal adhesion dependent cell adhesion and stimulate osteogenic differentiation of hMSCs.