cpTi Surfaces Research Articles

Anti-bacterium influenced corrosion effect of antibacterial Ti-3Cu alloy in Staphylococcus aureus suspension for biomedical application

Titanium and titanium alloys have been widely used as dental and orthopedic materials. The infection and the bacterium influenced corrosion both are concerned problems. Ti-3Cu alloy exhibits strong antibacterial properties against E. coli and S. aureus. The strong antibacterial properties of Ti-3Cu provides with a potential new method to reduce the bacterium influenced corrosion. S. aureus suspension was selected to simulate a serious bacterial condition. The corrosion behavior of Ti-3Cu alloy in S. aureus suspension was investigated by an electrochemical testing and an immersion test in comparison with pure titanium. Electrochemical results showed that Ti-3Cu exhibited a much better anti-corrosion property than cp-Ti in S. aureus suspension. Surface observation demonstrated that no corrosion pit was observed on Ti-3Cu alloy after 30 days immersion in the suspension while lots of corrosion pits were found on cp-Ti. The biofilm formation on the surface was observed by scanning electronic microscopy (SEM) in different periods. It has been revealed that S. aureus could grow and gather on the surface of cp-Ti to form biofilm after 18 h immersion, but only several bacteria were found on Ti-3Cu alloy even after 24 h immersion, displaying that Ti-3Cu alloy exhibits very strong anti-adhesion properties against S. aureus. It was concluded that Ti-3Cu performs a super anti-corrosion property due to the strong anti-adhesion property, in which Ti2Cu precipitate plays a critical role.

Effects of titanium oxide surface properties on bone-forming and soft tissue-forming cells.

Previous studies have concluded that certain titanium oxide (TiO2 ) surface properties promote bone-forming cell attachment. However, no comprehensive studies have investigated the effects of TiO2 surface and film morphology on hard and soft tissues. The aim of this study is to understand the effects of TiO2 morphology on the proliferation and differentiation of murine preosteoblasts (MC3T3-E1) and proliferation of human gingival fibroblasts (HGF-1) using in vitro experiments. Samples were fabricated with several TiO2 thickness and crystalline structure to mimic various dental implant surfaces. in vitro analysis was performed for 1, 3, and 7 days on these samples to assess the viability of MC3T3-E1 and HGF-1 cells in contact with the modified oxide surfaces. Results showed that HGF-1 cells exhibited no significant difference in viability on modified oxide surfaces versus a titanium control across experiments. MC3T3-E1 cells exhibited a significantly higher viability for the modified oxide surface in 1 day experiments, but not in 3 or 7 day experiments. Alkaline phosphatase expression in MC3T3-E1 was not significantly different on modified oxide surfaces versus the control across all experiments. A slight positive trend in viability was observed for cells in contact with rougher modified oxide surfaces versus a titanium control in both cell types. These observations suggest that crystallinity and thickness do not affect the long-term viability of hard or soft tissue cells when compared to a cpTi surface. Therefore, treatments like anodization on implant components may not directly affect the attachment of hard or soft tissue cells in vivo.

Distinguishing the influence of aluminium and vanadium additions on microstructural evolution and densification behaviour during the sintering of ti6Al, ti4V and ti6al4v

ABSTRACTIn this work, the influence of pure Al (Ti6Al) and V (Ti4 V) powder additions on the sintering behaviour of a coarse CP-Ti powder compact was investigated. Pure Al melts and spreads to form intermetallic layers at the CP-Ti surface, causing swelling and prevention of sintering and shrinkage below 1050°C. Ti4 V compacts do not swell and begin to sinter at 990°C. The sinter rate for both Ti4 V and Ti6Al are similar at 1200°C and higher than the CP-Ti compact alone. Aluminium melting distributes this element better than the dispersed V particles, leading to more rapid homogenisation. When both pure Al and V are present (Ti6Al4 V), the sintering rate at 1200°C is similar to that of Ti6Al and Ti4 V. However, swelling is increased and homogenisation is slower, resulting in a reduced sintering aid effect compared to Ti6Al and Ti4 V.

In vitro cell response on CP-Ti surfaces functionalized with TGF-β1 inhibitory peptides.

Osseointegration of implants is conversely related to the generation of a fibrous tissue capsule around the implant by the host environment. Although TGF-β1 plays many roles in regeneration processes, it is the cytokine to be mostly associated to the production of fibrotic tissue and thus, its inhibition has demonstrated to be beneficial to prevent several fibrotic reactions. Surface biofunctionalization enables the immobilization of biologically active molecules on an implant surface to tailor the biological response of the host. Here, we studied in vitro biological effects of biofunctionalized CP-Ti surfaces with a TGF-β1 inhibitor peptide, P144. A reliable biofunctionalization process that tethers P144 peptides to commercially pure titanium was developed. Differentiation of human mesenchymal stem cells, osteoblasts and fibroblasts on P144-functionalized and control surfaces was assessed at the gene expression and protein production levels. Results showed that P144-functionalized surfaces reduced expression and production of fibrotic differentiation markers and increased osteoblastic differentiation markers. Therefore, biofunctionalization of surfaces with TGF-β1 inhibitor peptides are an alternative promising strategy for inducing osseointegration around medical devices and implants.

Dual nanofibrous bioactive coating and antimicrobial surface treatment for infection resistant titanium implants

Failures of biomedical implants due to implant-related infections and implant loosening remains a major concern in orthopaedic fixations. The current work aims to address the issues by examining the effect of dual interaction i.e surface modification and surface coatings on orthopaedic implant materials, i.e. commercially pure titanium (cpTi). The cpTi surface was initially modified with piranha solution (H2SO4 + H2O2) to create an antibacterial surface. Further, the biological properties similar to bone tissue were improved by electrospun coating on the piranha treated substrate with poly(ε-caprolactone)(PCL)/hydroxyapatite (HA) composite nanofibers. The PCL/HA composite nanofibers have been characterized using SEM, XRD, EDS contact angle measurements, and FTIR spectroscopy. The coating adhesion of PCL/HA on cpTi was evaluated by cross-cut tape test (ASTM D3359-09). The newly fabricated substrates showed favourable properties and higher wettability. The antibacterial tests on piranha treated nanostructured substrates also confirmed a substantial reduction in bacterial growth over large areas. Cellular interactive responses such as adhesive and proliferation of osteosarcoma MG-63 cell lines has also demonstrated that presence of PCL/HA electrospun coating on the modified surface have improved the biological properties. The currently developed piranha treated and PCL/HA nanocomposite coated cpTi substrates seems to be a promising method to obtain both antibacterial and bioactive titanium surfaces.

Antibacterial photocatalytic activity of different crystalline TiO2 phases in oral multispecies biofilm

ObjectiveTitanium dioxide (TiO2) incorporation in biomaterials is a promising technology due to its photocatalytic and antibacterial activities. However, the antibacterial potential of different TiO2 crystalline structures on a multispecies oral biofilm remains unknown. We hypothesized that the different crystalline TiO2 phases present different photocatalytic and antibacterial activities. MethodsThree crystalline TiO2 films were deposited by magnetron sputtering on commercially pure titanium (cpTi), in order to obtain four groups: (1) machined cpTi (control); (2) A-TiO2 (anatase); (3) M-TiO2 (mixture of anatase and rutile); (4) R-TiO2 (rutile). The morphology, crystalline phase, chemical composition, hardness, elastic modulus and surface free energy of the surfaces were evaluated. The photocatalytic potential was assessed by methylene blue degradation assay. The antibacterial activity was evaluated on relevant oral bacteria, by using a multispecies biofilm (Streptococcus sanguinis, Actinomyces naeslundii and Fusobacterium nucleatum) formed on the treated titanium surfaces (16.5h) followed by UV-A light exposure (1h) to generate reactive oxygen species production. ResultsAll TiO2 films presented around 300nm thickness and improved the hardness and elastic modulus of cpTi surfaces (p<0.05). A-TiO2 and M-TiO2 films presented superior photocatalytic activity than R-TiO2 (p<0.05). M-TiO2 revealed the greatest antibacterial activity followed by A-TiO2 (≈99.9% and 99% of bacterial reduction, respectively) (p<0.001 vs. control). R-TiO2 had no antibacterial activity (p>0.05 vs. control). SignificanceThis study brings new insights on the development of extra oral protocols for the photocatalytic activity of TiO2 in oral biofilm-associated disease. Anatase and mixture-TiO2 showed antibacterial activity on this oral bacterial biofilm, being promising surface coatings for dental implant components.

Electrochemical behavior of titanium exposed to a biofilm supplemented with different sucrose concentrations

Statement of problemBiofilms can reduce the corrosion resistance of titanium because of the bacterial metabolism of fermentable carbohydrates, including sucrose. However, studies evaluating whether biofilms exposed to higher sucrose concentrations can affect the electrochemical behavior of titanium are lacking. PurposeThe purpose of this in vitro study was to test the electrochemical behavior of titanium previously exposed to biofilm supplemented with different sucrose concentrations. Material and methodsStreptococcus mutans UA159 biofilms were formed on commercially pure titanium (cpTi) surfaces and supplemented constantly with different sucrose concentrations (0%, 1%, 10%, and 40%) for 7 days (experimental groups) (n=12 per group). CpTi disks without biofilm were used as a control (n=12). The standard electrochemical tests open-circuit potential, electrochemical impedance spectroscopy, and potentiodynamic curve were performed. Data were submitted to ANOVA and the Tukey honestly significant difference (HSD) tests (α=.05). ResultsThe biofilm exposed to sucrose had an increased biofilm dry weight (P<.05). The polysaccharide amount and the pH drop were higher in the groups exposed to sucrose (P<.05). No difference was noted between the control and experimental groups for the electrochemical properties of cpTi (P>.05). ConclusionsBiofilms exposed to greater carbohydrate concentration did not alter the corrosive behavior of titanium.

Effect of a hybrid micro/nano-integrated titanium surface on behavior of rat osteoblasts

The objective of this study was to investigate the effect of a new combined micro/nanoscale implant surface feature on osteoblasts’ behaviors including cell morphology, adhesion, proliferation, differentiation, and mineralization in vitro. A new micro/nano-hybrid topography surface was fabricated on commercial pure titanium (Cp Ti) by a two-step sandblasted acid-etching and subsequent alkali- and heattreatment (SA-AH). The conventional sandblasted/acid-etching (SA) treatment and alkali and heat (AH) treatment were also carried out on the Cp Ti as controls. Surface microstructures of the Ti disc samples were assessed by scanning electron microscopy (SEM). The neonatal rat calvaria-derived osteoblasts were seeded on these discs and the initial cell morphology was evaluated by SEM and immunofluorescence. Initial adhesion of the cells was then assayed by DAPI staining at 1, 2, and 4 h after seeding. The Cell Counting Kit-8 (CCact K8) assay, gene expression of osteoblastic markers (ALP, Col 1, OCN, BSP, OSX, Cbfα1) and Alizarin Red S staining assays were monitored respectively for cell proliferations, differentiation and mineralization. The results show significant differences in osteoblast’s behaviors on the four kinds of Ti surfaces. Compared with Cp Ti surface, the SA and AH treatment can significantly promote cell adhesion, differentiation and mineralization of osteoblasts. In particular, the combined SA and AH treatments exhibit synergistic effects in comparison with the treatment of SA and AH individually, and are more favorable for stimulating a series of osteogenous responses from cell adhesion to mineralization of osteoblasts. In summary, this study provides some new evidence that the integrated micro/nanostructure on the Cp Ti surface may promote bone osseointegration between the Ti implantbone interfaces in vitro.

Optimization of Oxidation Temperature for Commercially Pure Titanium to Achieve Improved Corrosion Resistance

Thermal oxidation of commercially pure titanium (cp-Ti) was carried out at different temperatures, ranging from 200 to 900 °C to achieve optimum corrosion resistance of the thermally treated surface in simulated body fluid. Scanning electron microscopy, x-ray diffraction, Raman spectroscopy and electrochemical impedance spectroscopy techniques were used to characterize the oxides and assess their protective properties exposed in the test electrolyte. Maximum resistance toward corrosion was observed for samples oxidized at 500 °C. This was attributed to the formation of a composite layer of oxides at this temperature comprising Ti2O3 (titanium sesquioxide), anatase and rutile phases of TiO2 on the surface of cp-Ti. Formation of an intact and pore-free oxide-substrate interface also improved its corrosion resistance.

Three-species biofilm model onto plasma-treated titanium implant surface

In this study, titanium (Ti) was modified with biofunctional and novel surface by micro-arc oxidation (MAO) and glow discharge plasma (GDP) and we tested the development of a three-species periodontopatogenic biofilm onto the treated commercially-pure titanium (cpTi) surfaces. Machined and sandblasted surfaces were used as control group. Several techniques for surface characterizations and monoculture on bone tissue cells were performed. A multispecies biofilm composed of Streptococcus sanguinis, Actinomyces naeslundii and Fusobacterium nucleatum was developed onto cpTi discs for 16.5h (early biofilm) and 64.5h (mature biofilm). The number of viable microorganisms and the composition of the extracellular matrix (proteins and carbohydrates) were determined. The biofilm organization was analyzed by scanning electron microscopy (SEM) and Confocal laser scanning microscopy (CLSM). In addition, MC3T3-E1 cells were cultured on the Ti surfaces and cell proliferation (MTT) and morphology (SEM) were assessed. MAO treatment produced oxide films rich in calcium and phosphorus with a volcano appearance while GDP treatment produced silicon-based smooth thin-film. Plasma treatments were able to increase the wettability of cpTi (p<0.05). An increase of surface roughness (p<0.05) and formation of anatase and rutile structures was noted after MAO treatment. GDP had the greatest surface free energy (p<0.05) while maintaining the surface roughness compared to the machined control (p>0.05). Plasma treatment did not affect the viable microorganisms counts, but the counts of F. nucleatum was lower for MAO treatment at early biofilm phase. Biofilm extracellular matrix was similar among the groups, excepted for GDP that presented the lowest protein content. Moreover, cell proliferation was not significantly affected by the experimental, except for MAO at 6days that resulted in an increased cell proliferative. Together, these findings indicate that plasma treatments are a viable and promising technology to treat bone-integrated dental implants as the new surfaces displayed improved mechanical and biological properties with no increase in biofilm proliferation.

Biofunctionalization of commercially pure titanium with chitosan/hydroxyapatite biocomposite via silanization: evaluation of biological performances

Chitosan (CS) and hydroxyapatite (HA) bioactive molecules have been grafted onto commercially pure titanium surfaces (cpTi) to promote osteoblast adhesion and bone growth. The major challenge of this type of grafting is the attachment of the CS/HA biocomposite to the cpTi surface. In this study cpTi is biofunctionalized with CS/HA biocomposite material via silanization and the coated specimens were characterized using X-ray diffraction (XRD), scanning electron microscopy (SEM), water contact angle measurement and attenuated total reflectance-Fourier transform infrared (ATR-FTIR). The cpTi specimens were further evaluated for their in vitro bioactivity, hemocompatibility, protein adsorption and cell viability. The SEM micrographs showed uniform coatings adhered on cpTi specimens. The XRD and ATR-FTIR confirmed the presence of CS and HA on the cpTi specimens. The coated specimens showed improved in vitro bioactivity and hemocompatibilty along with enhanced adsorption of specific proteins. The cell viability studies showed non-cytotoxic nature of all the specimens and exhibited greater cell viability in the titanium CS/HA specimens. Hence, the studies showed that functionalized cpTi with covalent coating of CS/HA has significant potential in biomedical device implantation with improved bioactive properties.

A novel method of surface modification by electrochemical deoxidation: Effect on surface characteristics and initial bioactivity of zirconia.

The aim of this study was to investigate and compare the surface characteristics and initial bioactivity of ceria-stabilized zirconia/alumina nanocomposite (NANOZR) with those of yttria-stabilized zirconia (3Y-TZP) and pure titanium (CpTi) following the use of three surface modification methods; polishing, sandblasting/acid-etching (SB-E) and electrochemical deoxidation (ECD). Physical properties including surface morphology, chemical composition, X-ray diffraction, surface wettability, surface roughness, and hardness were measured. Osteoblast-like MC3T3-E1 cells were used to examine cell morphology and attachment to the surfaces of the materials. ECD treated NANOZR (NANOZR-E) showed a well-arranged, self-organized microporous surface structure with significantly low contact angles when compared with the other specimens (p < 0.05). NANOZR-E also demonstrated a slight decrease in monoclinic phase content (-4.4 wt %). The morphology and attachment of MC3T3-E1 cells on NANOZR-E were similar to those on polished and SBE-treated CpTi surfaces. Higher cell affinity was observed on NANOZR-E when compared with ECD treated 3Y-TZP. The findings of this study indicate the effectiveness of the novel technique, ECD, in the formation of a microporous surface on NANOZR when compared with both CpTi and 3Y-TZP. Moreover, this method also appears to improve the biological activity of NANOZR during the initial stage. © 2016 Wiley Periodicals, Inc. J Biomed Mater Res Part B: Appl Biomater, 105B: 2641-2652, 2017.

Formation of mixed and patterned self-assembled films of alkylphosphonates on commercially pure titanium surfaces

Titanium is extensively employed in biomedical devices, in particular as implant. The self-assembly of alkylphosphonates on titanium surfaces enable the specific adsorption of biomolecules to adapt the implant response against external stimuli. In this work, chemically-tailored cpTi surfaces were prepared by self-assembly of alkylphosphonate molecules. By bringing together attributes of two grafting molecules, aqueous mixtures of two alkylphosphonates were used to obtain mixed self-assembled films. Single self-assembled films were also altered by laser abrasion to produce chemically patterned cpTi surfaces. Both mixed and patterned self-assembled films were confirmed by AFM, ESEM and X-ray photoelectron spectroscopy. Water contact angle measurements also revealed the composition of the self-assembly films. Chemical functionalization with two grafting phosphonate molecules and laser surface engineering may be combined to guide the bone-like formation on cpTi, and the future biological response in the host.

Synthesis of porous Ce-doped titania coating containing CaTiO3 by MAO and its apatite inducing ability

Abstract Bioactive porous CaTiO 3 -contained titania coatings doped with cerium were prepared on CP-Ti surfaces by micro arc oxidation (MAO) process. The surface morphologies, chemical composition, wettability and the phase compositions of coatings were investigated by scanning electron microscopy (SEM), energy dispersion X-ray spectrometry (EDS), contact angle goniometer and X-ray diffraction (XRD), respectively. The results showed the surface phase compositions of the as-synthesized coatings are anatase, rutile TiO 2 and perovskite CaTiO 3 phases, as well as a few amorphous phases. The participation of Ce in the electrolyte during MAO is evidenced to benefit in crystallizing CaTiO 3 phase and enhancing the coating surface hydrophilicity. The results of simulated body fluid (SBF) immersion experiments indicate that the hydrolysis of CaTiO 3 during immersion could enhance the nucleation and growth of apatite. In comparison, the porous Ce-doped titania coating containing CaTiO 3 exhibits better bioactivity as more apatites were observed at the same immersion duration.

Peel strength and interfacial characterization of maxillofacial silicone elastomers bonded to titanium

ObjectivesTo investigate the effect of three adhesive primers on the morphology, chemistry and peel bond strength of two maxillofacial silicone elastomers with commercially pure titanium (cpTi). MethodsThe effect of three primers (PR2:A-304 Primer/A-320 Bonding Enhancer, PR3:Super Bond, and PR4:Super Glue) on cpTi morphology and chemistry were studied by reflected light polarized microscopy (RPOLM) and reflection Fourier-transform infrared microspectroscopy (RFTIRM). For testing the bond strength between two elastomers (EL1:MDX4-4210, EL2:A-2006) and primed cpTi surfaces, a 90° T peel test was performed (PBS), using as reference EL1, EL2 specimens bonded to heat-cured poly(methyl methacrylate) resin (PMMA) primed with A-330G primer (PR1). Failure modes were analyzed under a stereomicroscope, and the percentage of remaining silicone (RS%) on cpTi and PMMA were calculated by image analysis. Scanning electron microscopy/energy dispersive X-ray spectrometry (SEM/EDX) was used to investigate representative failure patterns on cpTi. Data were analyzed with Weibull analysis, ANOVA plus post hoc tests, and Pearson correlation coefficient (a=0.05). ResultsThick-irregular (PR2), thin-smooth (PR3), and uniform-porous (PR4) films were identified on cpTi by RPOLM. RFTIRM revealed: a strong peak of Si–O–Si with a distribution following the outline of the image (PR2); COO-M groups developed, but unevenly distributed (PR3); and reduction in CC groups due to in situ polymerization (PR4). Following PBS, the ranking of the statistical significant differences in Weibull scale parameter (σ0) of the EL1 group was PMMA_PR1>cpTi_PR2,cpTi_PR3>cpTi_PR4, whereas for the EL2 group cpTi_PR2>PMMA_PR1>cpTi_PR4,cpTi_PR3. For RS%, the ranking in the EL1 group was: PMMA_PR1>cpTi_PR2>cpTi_PR3>cpTi_PR4, and in the EL2 cpTi_PR2>cpTi_PR3>cpTi_PR4,PMMA_PR1. There was no statistically significant correlation between PBS and RS%, with the exception of EL1_PMMA_PR1. In all groups mixed failure modes were found by SEM/EDX. SignificanceAlthough there is evidence of bonding with cpTi, there are important differences among the primer/elastomer combination that may affect the clinical performance of these materials.

Surface-treated commercially pure titanium for biomedical applications: Electrochemical, structural, mechanical and chemical characterizations

Modified surfaces have improved the biological performance and biomechanical fixation of dental implants compared to machined (polished) surfaces. However, there is a lack of knowledge about the surface properties of titanium (Ti) as a function of different surface treatment. This study investigated the role of surface treatments on the electrochemical, structural, mechanical and chemical properties of commercial pure titanium (cp-Ti) under different electrolytes. Cp-Ti discs were divided into 6 groups (n=5): machined (M—control); etched with HCl+H2O2 (Cl), H2SO4+H2O2 (S); sandblasted with Al2O3 (Sb), Al2O3 followed by HCl+H2O2 (SbCl), and Al2O3 followed by H2SO4+H2O2 (SbS). Electrochemical tests were conducted in artificial saliva (pHs 3; 6.5 and 9) and simulated body fluid (SBF—pH7.4). All surfaces were characterized before and after corrosion tests using atomic force microscopy, scanning electron microscopy, energy dispersive microscopy, X-ray diffraction, surface roughness, Vickers microhardness and surface free energy. The results indicated that Cl group exhibited the highest polarization resistance (Rp) and the lowest capacitance (Q) and corrosion current density (Icorr) values. Reduced corrosion stability was noted for the sandblasted groups. Acidic artificial saliva decreased the Rp values of cp-Ti surfaces and produced the highest Icorr values. Also, the surface treatment and corrosion process influenced the surface roughness, Vickers microhardness and surface free energy. Based on these results, it can be concluded that acid-etching treatment improved the electrochemical stability of cp-Ti and all treated surfaces behaved negatively in acidic artificial saliva.

The effect of simulated inflammatory conditions on the surface properties of titanium and stainless steel and their importance as biomaterials

This work compares the surface modifications induced by the immersion in solutions that simulate inflammatory conditions of pure titanium (cpTi) and medical grade stainless steel (SS). The inflammatory conditions were simulated using a mixture of Hartman solution and 50mM of hydrogen peroxide (H2O2) at pH=5.2. The samples were immersed by 7days refreshing the solution every day to keep the reactivity of the H2O2. The surface characteristics that were investigated were: elemental composition by X-ray photoelectron spectroscopy (XPS); topography by atomic force microscopy (AFM) and profilometry; wettability and surface energy by sessile drop contact angle and point of zero charge by titration. Moreover, the variations in the electrochemical response were evaluated by open circuit potential (OCP), electrochemical impedance spectroscopy (EIS) and potentiodynamic polarization (PP) performed before and after the treatment using the Hartman solution as the electrolyte. The XPS results indicated that for both metallic samples, oxidation of the surface was promoted and/or the oxide layer was thicker after the immersion. The roughness and the solid-liquid surface energy were increased; the samples showed a more hydrophilic character after the treatment. However, the surface energy of the solid estimated using the Van Oss–Chaudhury–Good approach showed different trends between the cpTi and the SS surfaces; the polar component decreased for cpTi, while it increased for SS. Finally, the electrochemical results indicated that the corrosion resistance (Rcor) and the pore resistance (Rpo) significantly decreased for cpTi, while both resistances were not significantly different for the SS. This is indicative of a higher dissolution of the cpTi compared to SS and the lower Rpo means that the species are easily transported through the surface layer, which can be explained in terms of the formation of a porous TiOx layer, not observed on the SS. The cpTi surface suffered from a dissolution/oxidation process that allows its integration with the surrounding media, while the SS remained completely passive and this different response might be related to their distinguished clinical outcome.

Understanding compressive deformation behavior of porous Ti using finite element analysis

In the present study, porous commercially pure (CP) Ti samples with different volume fraction of porosities were fabricated using a commercial additive manufacturing technique namely laser engineered net shaping (LENS™). Mechanical behavior of solid and porous samples was evaluated at room temperature under quasi-static compressive loading. Fracture surfaces of the failed samples were analyzed to determine the failure modes. Finite Element (FE) analysis using representative volume element (RVE) model and micro-computed tomography (CT) based model have been performed to understand the deformation behavior of laser deposited solid and porous CP-Ti samples. In vitro cell culture on laser processed porous CP-Ti surfaces showed normal cell proliferation with time, and confirmed non-toxic nature of these samples.

Engineered protein coatings to improve the osseointegration of dental and orthopaedic implants

Here we present the design of an engineered, elastin-like protein (ELP) that is chemically modified to enable stable coatings on the surfaces of titanium-based dental and orthopaedic implants by novel photocrosslinking and solution processing steps. The ELP includes an extended RGD sequence to confer bio-signaling and an elastin-like sequence for mechanical stability. ELP thin films were fabricated on cp-Ti and Ti6Al4V surfaces using scalable spin and dip coating processes with photoactive covalent crosslinking through a carbene insertion mechanism. The coatings withstood procedures mimicking dental screw and hip replacement stem implantations, a key metric for clinical translation. They promoted rapid adhesion of MG63 osteoblast-like cells, with over 80% adhesion after 24 h, compared to 38% adhesion on uncoated Ti6Al4V. MG63 cells produced significantly more mineralization on ELP coatings compared to uncoated Ti6Al4V. Human bone marrow mesenchymal stem cells (hMSCs) had an earlier increase in alkaline phosphatase activity, indicating more rapid osteogenic differentiation and mineral deposition on adhesive ELP coatings. Rat tibia and femur in vivo studies demonstrated that cell-adhesive ELP-coated implants increased bone-implant contact area and interfacial strength after one week. These results suggest that ELP coatings withstand surgical implantation and promote rapid osseointegration, enabling earlier implant loading and potentially preventing micromotion that leads to aseptic loosening and premature implant failure.

Effect of the terminal group of phosphonate self-assembled films formed on Ti surfaces on the biomimetic layer formation and cell adhesion

ObjectivesTo evaluate the effect of different Self-Assembled Films (SAFs) on the development of calcium-phosphate (Ca/P) biomimetic layers on commercially pure titanium (cpTi) and the final cell adhesion on these coatings. Materials and methodsA total of five different surfaces were evaluated. Alkyl phosphonate Self-Assembled Films (SAFs) with three different ending groups (methyl [–CH3], carboxyl [–COOH], and phosphonate [–PO(OH)2]) were used to cover ultra-polished cpTi surfaces. These functionalized surfaces were compared with a hydroxylated ultra-polished cpTi surface. A biomimetic Ca/P layer was deposited on each surface by precipitation. A control cpTi sample with no precipitates was introduced in the study. Topography (AFM), morphology (ESEM), chemistry (XPS, EDX), crystallography (XRD), wettability (dynamic contact angle), layer thickness (WLCM), percolation (fluid retention) and cell response analysis were used for surface characterization. ResultsXRD showed the formation of hydroxyapatite (HA) in the four biomimetic coatings. The Ca/P ratios obtained by XPS in the four biomimetic coatings showed similar values (≈1.40) corresponding to amorphous hydroxyapatite. The water wettability of the biomimetic coatings was similar but the surface morphology was different. The thickest biomimetic coating with lower percolation threshold and greater cell adhesion was obtained on the carboxyl-terminated SAF. The biomimetic coatings improved the cell adhesion but it was further improved by the presence of underlying SAFs that bond the coating to cpTi surface. ConclusionsThe use of SAFs chemically stabilizes the biomimetic precipitates and guarantees higher cell adhesion than in absence of SAFs. The apatite nucleation and growth depended on the underlying SAF. Biomimetic coatings on hydroxylated surface increases cell adhesion but on SAFs functionalized surfaces achieve higher cell response. The SAFs with carboxyl ending group promoted the formation of thick and interconnected biomimetic coatings, with low fluid retention and a very significant cell response.