Transglutaminase enables highly hydrolytically and proteolytically stable crosslinking of collagen on titanium surfaces and promotes osteogenic differentiation of human mesenchymal stem cells

Collagen with its bioactive ligand motives would be predestined as coating on bone implant surfaces like titanium hip stems to facilitate receptor-mediated cell adhesion and thereby improve early osseointegration. Unfortunately, collagen as coating exhibits very low proteolytic resistance in vivo. To overcome this limitation, different crosslinking methods of collagen (transglutaminase, GTA, EDC/NHS, riboflavin, and lysyl oxidase) with silanized titanium alloy (Ti6Al4V) were investigated in terms of degradation resistance, hydrolysis stability, tensile strength, and metabolic cell activity. The in vitro osteogenic differentiation ability of human mesenchymal stem cells (hMSCs) induced by the surface modification was evaluated by immunofluorescence of early osteogenic markers, Alizarin red staining, and energy dispersive X-ray spectroscopy. The expression of the adhesion-related protein vinculin was analyzed on the different functionalized surfaces. The results revealed that the enzymatic crosslinker transglutaminase offered high degradation resistance, tensile strength, and hydrolysis stability compared to the other crosslinking reagents tested. Remarkably, the adhesion sequences within the collagen were accessible to the hMSCs despite the transglutaminase crosslinking procedure. In conclusion, the organochemical functionalization of Ti6Al4V surfaces with collagen using transglutaminase holds great potential to facilitate an enhanced interaction with attached bone cells and thereby could potentially improve and accelerate osseointegration of a titanium-based bone implant in vivo.

Enhancement of in vitro antibacterial activity and bioactivity of iodine-loaded titanium by micro-scale regulation using mixed-acid treatment

Postoperative infection and subsequent device loss are serious complications in the use of titanium dental implants and plates for jawbone reconstruction. We have previously reported that NaOH-CaCl2 -thermal-ICl3 -treated titanium (NaCaThIo) has a nano-scale surface and exhibits antibacterial activity against Staphylococcus aureus. The present study examined the surface properties of mixed-acid treated and then iodine-treated titanium (MA-NaCaThIo), and evaluated oral antibacterial activity and cytotoxicity compared with the results obtained with NaCaThIo. MA-NaCaThIo formed a surface layer with a nano-scale network structure having microscale irregularities, and both the thickness of the surface layer (1.49 ± 0.16 μm) and the average surface roughness (0.35 ± 0.03 μm) were significantly higher than those of NaCaThIo. Furthermore, MA-NaCaThIo maintained high hydrophilicity with a contact angle of 7.5 ± 1.7° even after 4 weeks, as well as improved apatite formation, iodine ion release, and antibacterial activity against Prevotella intermedia compared to NaCaThIo. Cell culture test revealed that MA-NaCaThIo exhibited no cytotoxicity against MG-63 and Vero cells, while increased cell proliferation, ALP activity and mineralization of MG-63 compared to NaCaThIo. This treated titanium is expected to be useful for the development of next-generation titanium devices having both bone-bonding and antibacterial properties.

"Off-Label Use" of the Siderophore Enterobactin Enables Targeted Imaging of Cancer with Radioactive Ti(IV)

The development of inert, biocompatible chelation methods is required to harness the emerging positron emitting radionuclide 45Ti for radiopharmaceutical applications. Herein, we evaluate the Ti(IV)-coordination chemistry of four catechol-based, hexacoordinate chelators using synthetic, structural, computational, and radiochemical approaches. The siderophore enterobactin (Ent) and its synthetic mimic TREN-CAM readily form mononuclear Ti(IV) species in aqueous solution at neutral pH. Radiolabeling studies reveal that Ent and TREN-CAM form mononuclear complexes with the short-lived, positron-emitting radionuclide 45Ti(IV), and do not transchelate to plasma proteins in vitro and exhibit rapid renal clearance in naïve mice. These features guide efforts to target the 45Ti isotope to prostate cancer tissue through the design, synthesis, and evaluation of Ent-DUPA, a small molecule conjugate composed of a prostate specific membrane antigen (PSMA) targeting peptide and a monofunctionalized Ent scaffold. The [45Ti][Ti(Ent-DUPA)]2- complex forms readily at room temperature. In a tumor xenograft model in mice, selective tumor tissue accumulation (8±5 %, n=5), and low off-target uptake in other organs is observed. Overall, this work demonstrates targeted imaging with 45Ti(IV), provides a foundation for advancing the application of 45Ti in nuclear medicine, and reveals that Ent can be repurposed as a 45Ti-complexing cargo for targeted nuclear imaging applications.

Impact of autologous platelet concentrates on the osseointegration of dental implants

Osseointegration is defined as the direct deposition of bone onto biomaterial devices, most commonly composed from titanium, for the purpose of anchoring dental prostheses. The use of autologous platelet concentrates (APC) has the potential to enhance this process by modifying the interface between the host and the surface of the titanium implant. The rationale is to modify the implant surface and implant-bone interface via "biomimicry," a process whereby the deposition of the host's own proteins and extracellular matrix enhances the biocompatibility of the implant and hence accelerates the osteogenic healing process. This review of the available evidence reporting on the effect of APC on osseointegration explores in vitro laboratory studies of the interaction of APC with different implant surfaces, as well as the in vivo and clinical effects of APC on osseointegration in animal and human studies. The inherent variability associated with using autologous products, namely the unique composition of each individual's blood plasma, as well as the great variety in APC protocols, combination of biomaterials, and clinical/therapeutic application, makes it is difficult to make any firm conclusions about the in vivo and clinical effects of APC on osseointegration. The available evidence suggests that the clinical benefits of adding PRP and the liquid form of L-PRF (liquid fibrinogen) to any implant surface appear to be limited. The application of L-PRF membranes in the osteotomy site, however, may produce positive clinical effects at the early stage of healing (up to 6 weeks), by promoting early implant stability and reducing marginal bone loss, although no positive longer term effects were observed. Careful interpretation and cautious conclusions should be drawn from these findings as there were various limitations in methodology. Future studies should focus on better understanding of the influence of APCs on the biomaterial surface and designing controlled preclinical and clinical studies using standardized APC preparation and application protocols.

Construction of Magnesium Phosphate Chemical Conversion Coatings with Different Microstructures on Titanium to Enhance Osteogenesis and Angiogenesis

Titanium (Ti) and its alloys are widely used as hard tissue substitutes in dentistry and orthopedics, but their low bioactivity leads to undesirable osseointegration defects in the early osteogenic phase. Surface modification is an important approach to overcome these problems. In the present study, novel magnesium phosphate (MgP) coatings with controllable structures were fabricated on the surface of Ti using the phosphate chemical conversion (PCC) method. The effects of the microstructure on the physicochemical and biological properties of the coatings on Ti were researched. The results indicated that accelerators in PCC solution were important factors affecting the microstructure and properties of the MgP coatings. In addition, the coated Ti exhibited excellent hydrophilicity, high bonding strength, and good corrosion resistance. Moreover, the biological results showed that the MgP coatings could improve the spread, proliferation, and osteogenic differentiation of mouse osteoblast cells (MC3T3-E1) and vascular differentiation of human umbilical vein endothelial cells (HUVECs), indicating that the coated Ti samples had a great effect on promoting osteogenesis and angiogenesis. Overall, this study provided a new research idea for the surface modification of conventional Ti to enhance osteogenesis and angiogenesis in different bone types for potential biomedical applications.

Inflammatory tissue response in human soft tissue is caused by a higher particle load near carbon fiber-reinforced PEEK compared to titanium plates

Titanium as the leading implant material in locked plating is challenged by polymers such as carbon fiber-reinforced polyetheretherketone (CFR-PEEK), which became the focus of interest of researchers and manufacturers in recent years. However, data on human tissue response to these new implant materials are rare. Osteosynthesis plates and peri-implant soft tissue samples of 16 healed proximal humerus fractures were examined (n = 8 CFR-PEEK, n = 8 titanium). Soft tissue was analyzed by immunohistochemistry and µCT. The entrapped foreign bodies were further examined for their material composition by FTIR. To gain insight into their origin and formation mechanism, explanted and new plates were evaluated by SEM, EDX, profilometry and HR-CT. In the peri-implant soft tissue of the CFR-PEEK plates, an inflammatory tissue reaction was detected. Tissues contained foreign bodies, which could be identified as tantalum wires, carbon fiber fragments and PEEK particles. Titanium particles were also found in the peri-implant soft tissue of the titanium plates but showed a less intense surrounding tissue inflammation in immunohistochemistry. The surface of explanted CFR-PEEK plates was rougher and showed exposed and broken carbon fibers as well as protruding and deformed tantalum wires, especially in used screw holes, whereas scratches were identified on the titanium plate surfaces. Particles were present in the peri-implant soft tissue neighboring both implant materials and could be clearly assigned to the plate material. Particles from both plate materials caused detectable tissue inflammation, with more inflammatory cells found in soft tissue over CFR-PEEK plates than over titanium plates. Statement of Significance: Osteosynthesis plates are ubiquitously used in various medical specialties for the reconstruction of bone fractures and defects and are therefore indispensable for trauma surgeons, ENT specialists and many others. The leading implant material are metals such as titanium, but recently implants made of polymers such as carbon fiber-reinforced polyetheretherketone (CFR-PEEK) have become increasingly popular. However, little is known about human tissue reaction and particle generation related to these new implant types. To clarify this question, 16 osteosynthesis plates (n=8 titanium and n=8 CFR-PEEK) and the overlying soft tissue were analyzed regarding particle occurrence and tissue inflammation. Tissue inflammation is clinically relevant for the development of scar tissue, which is discussed to cause movement restrictions and thus contributes significantly to patient outcome.

Divalent Titanium via Reductive N-C Coupling of a TiIV Nitrido with π-Acids

The nitrido-ate complex [(PN)2Ti(N){μ2-K(OEt2)}]2 (1) reductively couples CO and isocyanides in the presence of DME or cryptand, to form rare, five-coordinate TiII complexes having a linear cumulene motif, [K(L)][(PN)2Ti(NCE)] (E = O, L = Kryptofix222, (2); E = NAd, L = 3 DME, (3); E = NtBu, L = 3 DME, (4); E = NAd, L = Kryptofix222, (5)). Oxidation of 2-5 with [Fc][OTf] afforded an isostructural TiIII center containing a neutral cumulene [(PN)2Ti(NCE)] (E = O, (6); E = NAd (7), NtBu (8)). Moreover, 1e- reduction of 6 and 7 in the presence of cryptand cleanly reformed corresponding discrete TiII complexes 2 and 5, which were further characterized by solution magnetization measurements and high- frequency and -field EPR (HFEPR) spectroscopy. Furthermore, oxidation of 7 with [Fc*][B(C6F5)4] resulted in a ligand disproportionated TiIV complex having transoid carbodiimides, [(PN)2Ti(NCNAd)2] (9). Comparison of spectroscopic, structural, and computational data for the divalent, trivalent, and tetravalent systems, including their 15N enriched isotopomers demonstrate these cumulenes to decrease in order of backbonding as TiII→TiIII→TiIV and increasing order of p-donation as TiII→TiIII→TiIV, thus displaying more covalency in TiIII species. Lastly, we show a synthetic cycle whereby complex 1 can deliver an N-atom to π-acids.

Influence of Ultrasound on the Characteristics of CaP Coatings Generated Via the Micro-arc Oxidation Process in Relation to Biomedical Engineering

Over the past decade, bone tissue engineering has been at the core of attention because of an increasing number of implant surgeries. The purpose of this study was to obtain coatings on titanium (Ti) implants with improved properties in terms of biomedical applications and to investigate the effect of ultrasound (US) on these properties during the micro-arc oxidation (MAO) process. The influence of various process parameters, such as time and current density, as well as US mode, on the properties of such coatings was evaluated. Novel porous calcium-phosphate-based coatings were obtained on commercially pure Ti. Their microstructure, chemical composition, topography, wettability, nanomechanical properties, thickness, adhesion to the substrate, and corrosion resistance were analyzed. In addition, cytocompatibility evaluation was checked with the human osteoblasts. The properties of the coatings varied significantly, depending on applied process parameters. The US application during the MAO process contributes to the increase of coating thickness, porosity, roughness, and skewness, as well as augmented calcium incorporation. The most advantageous coating was obtained at a current of 136 mA, time 450 s, and unipolar rectangular US, as it exhibits high porosity, adequate wettability, and beneficial skewness, which enabled increased adhesion and proliferation of osteoblasts during in vitro studies. Finally, the conducted research demonstrated the influence of various UMAO process parameters, which allowed for the selection of appropriate Ti implant modification for specific biomedical utilization.

UiO-66/AgNPs Coating for Dental Implants in Preventing Bacterial Infections

Titanium (Ti)-based biomaterials lack inherent antimicrobial activities, and the dental plaque formed on the implant surface is one of the main risk factors for implant infections. Construction of an antibacterial surface can effectively prevent implant infections and enhance implant success. Silver nanoparticles (AgNPs) exhibit broad antibacterial activity and a low tendency to induce drug resistance, but AgNPs easily self-aggregate in the aqueous environment, which significantly impairs their antibacterial activity. In this study, UiO-66/AgNP (U/A) nanocomposite was prepared, where zirconium metal-organic frameworks (UiO-66) were employed as the confinement matrix to control the particle size and prevent aggregation of AgNPs. The bactericidal activity of U/A against methicillin-resistant Staphylococcus aureus and Escherichia coli increased nearly 75.51 and 484.50 times compared with individually synthesized Ag. The antibacterial mechanism can be attributed to the enhanced membrane rupture caused by the ultrafine AgNPs on UiO-66, leading to protein leakage and generation of intracellular reactive oxygen species. Then, U/A was loaded onto Ti substrates (Ti-U/A) by using self-assembly deposition methods to construct an antibacterial surface coating. Ti-U/A exhibited excellent antibacterial activities and desired biocompatibility both in vitro and in vivo. The U/A nanocomposite coating technique is thus expected to be used as a promising surface modification strategy for Ti-based dental implants for preventing dental implant infections.

Biomechanical Fatigue Behavior of a Dental Implant Due to Chewing Forces: A Finite Element Analysis

The use of titanium as a biomaterial for the treatment of dental implants has been successful and has become the most viable and common option. However, in the last three decades, new alternatives have emerged, such as polymers that could replace metallic materials. The aim of this research work is to demonstrate the structural effects caused by the fatigue phenomenon and the comparison with polymeric materials that may be biomechanically viable by reducing the stress shielding effect at the bone-implant interface. A numerical simulation was performed using the finite element method. Variables such as Young's modulus, Poisson's coefficient, density, yield strength, ultimate strength, and the S-N curve were included. Prior to the simulation, a representative digital model of both a dental implant and the bone was developed. A maximum load of 550 N was applied, and the analysis was considered linear, homogeneous, and isotropic. The results obtained allowed us to observe the mechanical behavior of the dental implant by means of displacements and von Mises forces. They also show the critical areas where the implant tends to fail due to fatigue. Finally, this type of non-destructive analysis proves to be versatile, avoids experimentation on people and/or animals, and reduces costs, and the iteration is unlimited in evaluating various structural parameters (geometry, materials, properties, etc.).

Allergic reaction of poly-ether-ether-ketone versus titanium implants: A posttest-only control group design experimental study using a rabbit model

PURPOSE

The aim of this study was to determine clinically and genetically the allergic effects of titanium and poly-ether-ether-ketone (PEEK) implants following loading in rabbit tibias.

MATERIALS AND METHODS

This study included 18 white New Zealand male rabbits (n = 18) divided evenly into three groups: control, titanium (Ti), and PEEK (P). Clinically, the allergenic effect of titanium and PEEK was investigated by detecting the effect on lymph nodes. Furthermore, RT-PCR and ELISA were used to detect the expression of certain genes IL-6, TNF-α, OPG, RANKL, and RUNX-2 through both types of implants.

RESULTS

Our findings demonstrated that titanium implants induced enlarged lymph nodes, which PEEK did not. Overall, RT-PCR and ELISA techniques revealed that Ti implants had higher expression of the inflammatory genes IL-6 and TNF-α. Ti had the highest expression in OPG findings, while PEEK had the lowest. RANKL expression was highest in the control group and lowest in the PEEK group. RUNX-2 is the highest for the control group and the lowest for the titanium group.

CONCLUSION

Although titanium implants elicited greater allergy responses than PEEK implants, titanium has the highest expression of bone formation genes and the lowest expression of bone resorption genes, making it preferable to PEEK.

Mild aseptic lymphocyte-dominated vasculitis-associated lesion (ALVAL)-type reactions also present in patients with failed knee prostheses

Aims

Metal particles detached from metal-on-metal hip prostheses (MoM-THA) have been shown to cause inflammation and destruction of tissues. To further explore this, we investigated the histopathology (aseptic lymphocyte-dominated vasculitis-associated lesions (ALVAL) score) and metal concentrations of the periprosthetic tissues obtained from patients who underwent revision knee arthroplasty. We also aimed to investigate whether accumulated metal debris was associated with ALVAL-type reactions in the synovium.

Methods

Periprosthetic metal concentrations in the synovia and histopathological samples were analyzed from 230 patients from our institution from October 2016 to December 2019. An ordinal regression model was calculated to investigate the effect of the accumulated metals on the histopathological reaction of the synovia.

Results

Median metal concentrations were as follows: cobalt: 0.69 μg/g (interquartile range (IQR) 0.10 to 6.10); chromium: 1.1 μg/g (IQR 0.27 to 4.10); and titanium: 1.6 μg/g (IQR 0.90 to 4.07). Moderate ALVAL scores were found in 30% (n = 39) of the revised knees. There were ten patients with an ALVAL score of 6 or more who were revised for suspected periprosthetic joint infection (PJI), aseptic loosening, or osteolysis. R2 varied between 0.269 and 0.369 for the ordinal regression models. The most important variables were model type, indication for revision, and cobalt and chromium in the ordinal regression models.

Conclusion

We found that metal particles released from the knee prosthesis can accumulate in the periprosthetic tissues. Several patients revised for suspected culture-negative PJI had features of an ALVAL reaction, which is a novel finding. Therefore, ALVAL-type reactions can also be found around knee prostheses, but they are mostly mild and less common than those found around metal-on-metal prostheses.

Influence of Titanium Surface Residual Stresses on Osteoblastic Response and Bacteria Colonization

Grit basting is the most common process applied to titanium dental implants to give them a roughness that favors bone colonization. There are numerous studies on the influence of roughness on osseointegration, but the influence of the compressive residual stress associated with this treatment on biological behavior has not been determined. For this purpose, four types of surfaces have been studied using 60 titanium discs: smooth, smooth with residual stress, rough without stress, and rough with residual stress. Roughness was studied by optic interferometry; wettability and surface energy (polar and dispersive components) by contact angle equipment using three solvents; and residual stresses by Bragg-Bentano X-ray diffraction. The adhesion and alkaline phosphatase (ALP) levels on the different surfaces were studied using Saos-2 osteoblastic cultures. The bacterial strains Streptococcus sanguinis and Lactobacillus salivarius were cultured on different surfaces, determining the adhesion. The results showed that residual stresses lead to increased hydrophilicity on the surfaces, as well as an increase in surface energy, especially on the polar component. From the culture results, higher adhesion and higher ALP levels were observed in the discs with residual stresses when compared between smooth and roughened discs. It was also found that roughness was the property that mostly influenced osteoblasts' response. Bacteria colonize rough surfaces better than smooth surfaces, but no changes are observed due to residual surface tension.

Porous 3D Printed Titanium Cages in Anterior Cervical Discectomy and Fusion are Associated With Less Subsidence, Improved Maintenance of Segmental Lordotic Correction, and Similar Clinical Outcomes as Allograft

STUDY-DESIGN

Retrospective chart review.

OBJECTIVES

Investigate radiographic and clinical outcomes of 3D printed titanium cages (3DTC) vs allograft in patients undergoing Anterior cervical discectomy and fusion (ACDF).

METHODS

Consecutive series of patients undergoing ACDF with 3DTC were compared to patients using corticocancellous allograft. Cage subsidence, fusion status, sagittal alignment, and patient-reported-outcomes. Radiographic evaluation was performed on the closing intraoperative x-ray and compared to films at 6-weeks, 6-months, and 1-year. Cage subsidence was calculated based on the amount of settling into superior and inferior endplates compared to the intraoperative x-ray. Fusion was assessed based on < 1 mm of flexion/extension motion. Sagittal alignment parameters and patient-reported-outcomes were measured.

RESULTS

Seventy six-patients/(120 levels) in 3DTC group and 77-patients/(115 levels) in allograft group were evaluated. No significant differences were noted in patient demographics, level fused or the number of levels fused between the groups. The most common level fused was C5-6. 3DTC had a significantly lower subsidence rate at all-time points as compared to allograft (P < .001). 3DTC maintained segmental lordosis better than allograft at all-time points including 1-year postop (P < .001). No significant differences were noted in fusion rate for 3DTC vs allograft at 6-months (P > .05). There were no significant differences in patient-reported-outcomes.

CONCLUSION

3D printed titanium cages had similar patient-reported outcomes and fusion rates as allograft, but less subsidence at all-time points. 3D printed titanium cages better maintained the segmental lordosis at the operative level at all-time points. Although longer term evaluation is needed, based on these results, 3DTC appear to be viable graft options for ACDF that better maintain disc space height and improve segmental lordotic interbody correction.

A Polished Cobalt-Chrome Baseplate is not Associated With a Lower Revision Rate Than Matt Titanium in a Single Total Knee Arthroplasty Implant System With Identical Baseplate Design

BACKGROUND

Polished baseplates were introduced into total knee arthroplasty (TKA) systems to reduce the incidence of backside wear. In 2004, a fixed-bearing knee arthroplasty system underwent a change in baseplate material from matt titanium to polished cobalt-chrome (CoCr) with the intention to reduce backside wear. Other design aspects were left unchanged. The aim of this study was to compare these implants with each baseplate using data from the Australian Orthopaedic Association National Joint Replacement Registry.

METHODS

Primary TKA procedures performed between January 2010 and December 2021 for osteoarthritis, using a single design with cross-linked polyethylene inserts and matt titanium or polished CoCr baseplates, were analyzed. The primary outcome was all-cause revision, summarized using Kaplan-Meier estimates, with age- and sex-adjusted hazard ratios estimated from Cox proportional hazards models. In total, there were 2,091 procedures with matt titanium and 2,519 procedures with polished CoCr baseplates.

RESULTS

The 9-year cumulative percent revision was 2.5% (95% confidence interval [CI] 1.8 to 3.5%) and 4.2% (95% CI 3.1 to 5.6%) for the matt titanium and CoCr groups, respectively. Compared to matt titanium, the revision rate of CoCr baseplates was not significantly higher (hazard ratio 1.44; 95% CI 0.96 to 2.15; P = .076).

CONCLUSIONS

Polished CoCr baseplates in a single TKA system were not associated with reduced all-cause revision rates compared to matt titanium up to 11 years post-TKA. Our results suggest that the predicted reduction in wear particle debris production from polished CoCr baseplates may not correlate with reduced revision rates in vivo, but further evaluation is required.

Effect of implant type on the stability of cantilever fixed dental prostheses: An in vitro study

OBJECTIVES

To simulate the replacement of a premolar with an implant-supported cantilever fixed dental prosthesis (ICFDP) and how the fracture load is affected by implant type, positioning within the zirconia blank, and aging protocol.

MATERIALS AND METHODS

Seventy-two ICFDPs were designed either within the enamel- or dentin layer of a 4Y-PSZ blank for bone-level and tissue-level titanium-zirconium implants. Fracture load was obtained on the cantilever at baseline (no aging) or after aging in a chewing simulator with the load applied within the implant axis (axial aging) or on the cantilever (12 groups with n = 6). A three-way ANOVA was applied (α = .05).

RESULTS

A three-way ANOVA revealed a significant effect on fracture load values of implant type (p = .006) and aging (p < .001) but not for the position within the zirconia blank (p = .847). Fracture load values significantly increased from baseline bone level (608 ± 118 N) and tissue level (880 ± 293 N) when the implants were aged axially, with higher values for tissue level (1065 ± 182 N) than bone level (797 ± 113 N) (p < .001). However, when the force was applied to the cantilever, fracture load values decreased significantly for tissue-level (493 ± 70 N), while values for bone-level implants remained stable (690 ± 135 N).

CONCLUSIONS

For ICFDPs, the use of bone-level implants is reasonable as catastrophic failures are likely to be restricted to the restoration, whereas with tissue-level implants, the transmucosal portion of the implant is susceptible to deformation, making repair more difficult.

Effects of surface nanomorphology on the senescence of periodontal ligament stem cells

OBJECTIVES

The effect of TiO2 nanotube morphology on the differentiation potency of senescent periodontal ligament stem cells was investigated.

METHODS

Two types of titanium sheets with TiO2 nanotube morphology (20V-NT and 70V-NT) were prepared via anodic oxidation at 20 and 70 V separately, and their surface morphology was observed. Young periodontal ligament stem cells were cultivated in an osteogenic induction medium, and the most effective surface morphology in promoting osteogenic differentiation was selected. RO3306 and Nutlin-3a were used to induce the aging of young periodontal ligament stem cells, and senescent periodontal ligament stem cells were obtained. The osteogenic differentiation of senescent periodontal ligament stem cells was induced, and the effect of surface morphology on osteogenic differentiation was observed.

RESULTS

Nanotube morphology was achieved on the surfaces of titanium sheets through anodic oxidation, and the diameters of the nanotubes increased with voltage. A significant difference in the effect of nanotube morphology was found among nanotubes with different diameters in the young periodontal ligament stem cells. The surface nanotube morphology of 20V-NT had a more significant effect that promoted osteogenic differentiation. Compared with a smooth titanium sheet, the surface nanotube morphology of 20V-NT increased the number of alkaline phosphatase-positive senescent periodontal ligament stem cells and promoted calcium deposition and the expression of osteogenic marker genes Runt-related transcription factor 2, osteopontin, and osteocalcin.

CONCLUSIONS

A special nanotube morphology enhances the differentiation ability of senescent periodontal ligament stem cells, provides an effective method for periodontal regeneration, and further improves the performance of implants.

Cancer-Causing Effects of Orthopaedic Metal Implants in Total Hip Arthroplasty

BACKGROUND

Metal implants have been preferentially used in THA due to its biocompatibility, mechanical stability and durability. Yet concerns have emerged regarding their potential to release metallic ions, leading to long-term adverse effects, including carcinogenicity. This study aimed to investigate the risk of cancer development in patients with orthopaedic metal implants in total hip arthroplasty (THA).

METHODS

Patients with THA conducted at a local tertiary implant centre from 2001-2008 were linked to the local cancer registry and followed up to the end of 2023. Standardized incidence ratios (SIRs) for cancer incidence and its confidence interval by Poisson distribution were calculated. Survival analysis was depicted using the Kaplan-Meier method, and the log-rank test was used to assess the differences across groups.

RESULTS

The study cohort included 388 patients and 53 cancers diagnosed during follow-up, at least 5 years post THA. All-site cancer risks were increased in patients with THA (SIR: 1.97; 95% CI: 1.48-2.46), validated with chi-square analysis (chi-square = 15.2551, N = 100,388, p < 0.01). A statistically significant increase in multiple site-specific cancers including haematological cancers were identified.

CONCLUSIONS

Patients with THA were found to have an increased risk for cancer compared to the general population during a mean follow-up of 16 years.

Investigation of the Effect of Stress on Oxygen Diffusion in Pure Titanium Using a Phase-Field Model

Diffusion plays a vital role during the fabrication of many materials. It is a well-known fact that stress can influence diffusion behavior. In order to optimize material processing techniques, a quantitative evaluation of the effect of stress on diffusion is essentially required. By analyzing the free energy change in a Ti-O system during diffusion, a phase-field model was developed to address this issue. Using this model, the diffusion of oxygen atoms in pure titanium under different stress states was investigated. It was observed that the true equilibrium concentration of oxygen was proportional to its hydrostatic pressure. Tensile stress can increase the oxygen concentration. This raise in concentration decreased with temperature. However, the promotion of diffusion can be attained in deeper regions at a higher temperature. On the contrary, compressive stress inhibited the diffusion of oxygen in pure titanium. Under a certain compressive stress, the decrease in the oxygen concentration at the surface layer was more significant at a lower temperature, while a decrease could be observed at a deeper distance from the surface at a higher temperature. A thermodynamic explanation of the effect of stress on diffusion was given based on the proposed phase-field model.

Bond Analysis of Titanium Rods Embedded in Masonry

Among the techniques utilized for strengthening masonry structures with advanced materials, the adoption of near-surface mounted (NSM) titanium rods stands out as a promising method for increasing the flexural and shear strength of masonry structures. This method is also known as Bed Joint Reinforcement. Ensuring an effective performance of this technique hinges on establishing a strong bond between the NSM reinforcement and the substrate masonry material. The primary objective of this project was to study the mechanics of this bond using NSM threaded and smooth titanium rods while scrutinizing the impact of key parameters on bond performance. Variables under investigation encompassed the rod type (smooth and threaded), bond length, and the material used to fill the groove (type of mortars). It was found that threaded rods outperformed all other types investigated, and pull-out strengths can be significantly improved through careful selection and optimization of the mortar type and bond length.

Nanohydroxyapatite/Peptide Composite Coatings on Pure Titanium Surfaces with Nanonetwork Structures Using Oyster Shells

Titanium and its alloys are extensively applied in artificial tooth roots because of their excellent corrosion resistance, high specific strength, and low elastic modulus. However, because of their biological inertness, their surface needs to be modified to improve the osteointegration of titanium implants. The preparation of biologically active calcium-phosphorus coatings on the surface of an implant is one effective method for enhancing the likelihood of bone integration. In this study, osteoinductive peptides were extracted from oyster shells by using acetic acid. Two peptide-containing hydroxyapatite (HA) composite coatings were then prepared: one coating was prepared by hydrothermally synthesizing an HA coating in the presence of peptides (HA/P/M), and the other coating was prepared by hydrothermally synthesizing HA and then immersing the hydrothermally synthesized HA in a peptide solution (HA/P/S). Characterization results indicated that the composite HA coatings containing oyster shell-based peptides were successfully prepared on the alkali-treated pure titanium surfaces. The HA/P/M and HA/P/S composite coatings were found to exhibit excellent hydrophilicity. Protein adsorption tests confirmed that the HA/P/M and HA/P/S coatings had an approximately 2.3 times higher concentration of adsorbed proteins than the pure HA coating.

Structural, Electrical and Corrosion Properties of Bulk Ti-Cu Alloys Produced by Mechanical Alloying and Powder Metallurgy

Binary Ti100-x-Cux (x = 1.6 and 3.0 wt.%) alloys were produced by the application of mechanical alloying and powder metallurgy processes. The influence of the copper concentration in titanium on the microstructure and properties of bulk alloys was investigated. The synthesized materials were characterized by an X-ray diffraction technique, scanning electron microscopy, and chemical composition determination. The electrochemical and corrosion properties were also investigated. Cold compaction and sintering reduced the content of α-Ti content in Ti98.4-Cu1.6 and Ti97-Cu3 alloys to 92.4% and 83.7%, respectively. Open Circuit Potential measurements showed a positive shift after the addition of copper, suggesting a potential deterioration in the corrosion resistance of the Ti-Cu alloys compared to pure Ti. Electrochemical Impedance Spectroscopy analysis revealed significant improvement in electrical conductivity after the addition of copper. Corrosion testing results demonstrated compromised corrosion resistance of Ti-Cu alloys compared to pure Ti. In summary, the comprehensive investigation of Ti100-x-Cux alloys provides valuable insights for potential applications in biosensing.

Surface-Engineered Titanium with Nanoceria to Enhance Soft Tissue Integration Via Reactive Oxygen Species Modulation and Nanotopographical Sensing

The design of implantable biomaterials involves precise tuning of surface features because the early cellular fate on such engineered surfaces is highly influenced by many physicochemical factors [roughness, hydrophilicity, reactive oxygen species (ROS) responsiveness, etc.]. Herein, to enhance soft tissue integration for successful implantation, Ti substrates decorated with uniform layers of nanoceria (Ce), called Ti@Ce, were optimally developed by a simple and cost-effective in situ immersion coating technique. The characterization of Ti@Ce shows a uniform Ce distribution with enhanced roughness (∼3-fold increase) and hydrophilicity (∼4-fold increase) and adopted ROS-scavenging capacity by nanoceria coating. When human gingival fibroblasts were seeded on Ti@Ce under oxidative stress conditions, Ti@Ce supported cellular adhesion, spreading, and survivability by its cellular ROS-scavenging capacity. Mechanistically, the unique nanocoating resulted in higher expression of amphiphysin (a nanotopology sensor), paxillin (a focal adhesion protein), and cell adhesive proteins (collagen-1 and fibronectin). Ti@Ce also led to global chromatin condensation by decreasing histone 3 acetylation as an early differentiation feature. Transcriptome analysis by RNA sequencing confirmed the chromatin remodeling, antiapoptosis, antioxidant, cell adhesion, and TGF-β signaling-related gene signatures in Ti@Ce. As key fibroblast transcription (co)factors, Ti@Ce promotes serum response factor and MRTF-α nucleus localization. Considering all of this, it is proposed that the surface engineering approach using Ce could improve the biological properties of Ti implants, supporting their functioning at soft tissue interfaces and utilization as a bioactive implant for clinical conditions such as peri-implantitis.

Provision of bone conduction hearing implants in England in adults and children: a review of Hospital Episode Statistics data 2012-2021

OBJECTIVE

Bone conduction hearing implants are a well-established method of hearing rehabilitation in children and adults. This study aimed to review any changes in provision in England.

METHODS

The total number of bone conduction hearing implantations performed was analysed from 2012 to 2021 utilising Hospital Episode Statistics data for England.

RESULTS

The total number of procedures has increased by 58 per cent. One-stage bone conduction hearing implantations in adults accounts for the largest proportion of this increase (93 per cent of the total). The number performed in children has remained stable and accounts for 73 per cent (n = 433) of all two-stage procedures.

CONCLUSION

The data show that bone conduction hearing implant surgery is becoming increasingly popular, particularly in adults. This has correlated with the increase in availability, national recommendations and choice of devices.

Vacuum Plasma Treatment Device for Enhancing Fibroblast Activity on Machined and Rough Titanium Surfaces

This study was conducted to compare the effects of an innovative plasma surface treatment device that does not need a gas supply for titanium disks with two different surface topographies: the prototypical machined surface (MAC) and one of the most diffused roughened ones (SL) obtained through grit blasting and acid etching. A total of 200-MAC and 200-SL titanium disks were used. Each group of disks was divided into four sub-groups of 40 samples each that were subjected to five different tests. Among these, 150-MAC and 150-SL were considered the test group, and they were treated with plasma for 15, 30, and 60 s after being removed from the sterile packaging. On the other hand, 50-MAC and 50-SL were considered the control group, and they were only removed from sterile plastic vials. The samples were analyzed to evaluate the capability of the plasma treatment in influencing protein adsorption, cell adhesion, proliferation, and microbial growth on the test group disks when compared to the untreated disks. Protein adsorption was significantly enhanced after 20 min of plasma treatment for 15 and 30 s on the MAC and SL disks. Plasma treatment for 15 and 30 s significantly increased the level of adhesion in both treated samples after 30 min. Furthermore, the MAC samples showed a significant increase in cell adhesion 4 h after plasma treatment for 15 s. The SEM analysis highlighted that, on the treated samples (especially on the MAC disks), the cells with a polygonal and flat shape prevailed, while the fusiform- and globular-shaped cells were rare. The encouraging results obtained further confirm the effectiveness of plasma treatments on cell adhesion and fibroblast activity.

Growth dynamic of biofilm-associated Naegleria fowleri in freshwater on various materials

In industrial water systems, the occurrence of biofilm-associated pathogenic free-living amoebae (FLA) such as Naegleria fowleri is a potential hygienic problem, and factors associated with its occurrence remain poorly understood. This study aimed to evaluate the impact of four cooling circuit materials on the growth of N. fowleri in a freshwater biofilm formed at 42°C and under a hydrodynamic shear rate of 17 s-1 (laminar flow): polyvinyl chloride, stainless steel, brass, and titanium. Colonization of the freshwater biofilms by N. fowleri was found to be effective on polyvinyl chloride, stainless steel, and titanium. For these three materials, the ratio of (bacterial prey)/(amoeba) was found to control the growth of N. fowleri. All materials taken together, a maximum specific growth rate of 0.18 ± 0.07 h-1 was associated with a generation time of ~4 h. In contrast, no significant colonization of N. fowleri was found on brass. Therefore, the contribution of copper is strongly suspected.

The Influence of the Shielding-Gas Flow Rate on the Mechanical Properties of TIG-Welded Butt Joints of Commercially Pure Grade 1 Titanium

This article proposes as a novelty the differentiation of shielding-gas flow rates from both sides of the tungsten inert gas (TIG)-welded butt joints of commercially pure (CP) grade 1 titanium tubes. Such an approach is aimed at economically reducing the amount of protective gas used in TIG closed butt welding. The effect of the shielding-gas flow rate on the properties of CP grade 1 titanium butt-welded joints made using the tungsten inert gas (TIG)-welding method. Butt-welded joints were made for different values of the shielding-gas flow from the side of the root of the weld. Argon 5.0 was used as the shielding gas in the welding process. As part of the research, the welded joints obtained were analysed using optical and scanning electron microscopy. The microstructural characteristics of the joints were examined using an optical microscope, and the mechanical properties were determined using hardness and tensile tests. It was observed that as the flow of the shielding gas decreases, the hardness of the weld material increases and its brittleness also increases. A similar trend related to the amount of gas flow was also noticeable for the tensile strength of the joints. The increase in the hardness of the weld and the heat-affected zone compared to the base metal is mainly related to the increase in the amount of acicular structure (α' phase). The optimal gas flow rates from the side of the root of weld were found at the values of 12 dm3/min.

Analysis of the effect of reconstructing the ossicular chain under otoendoscopy with and without a stapes superstructure

BACKGROUND

Numerous studies have been conducted on the effect of the stapes superstructure after ossicular chain reconstruction, but the findings are not uniform.

OBJECTIVE

To compare the hearing outcomes of ossicular chain reconstruction with partial ossicular replacement prosthesis (PORP) or total ossicular replacement prosthesis (TORP) under otoendoscopy.

MATERIALS AND METHODS

The records of 111 patients diagnosed with chronic suppurative otitis media were retrospectively analyzed. These patients were divided into PORP group (n = 57) and TORP group (n = 54). They were further subdivided into subgroups PORP-a (with a malleus handle) and PORP-b (without a malleus handle), subgroups TORP-a and TORP-b. Pre- and postoperative audiometric results were analyzed.

RESULTS

The mean postoperative air conduction hearing thresholds improvement, mean air-bone gap improvement, and the success rate of reconstruction were significantly higher in the PORP group than in the TORP group (p < .05). The mean postoperative air conduction hearing thresholds improvement and the success rate of reconstruction were significantly higher in the PORP-a group than in the TORP-a group (p < .05); and similar results were concluded in comparison of the PORP-b group and the TORP-b group.

CONCLUSIONS AND SIGNIFICANCE

The stapes superstructure has an important positive effect on the postoperative outcome of endoscopic ossicular chain reconstruction.

Exploring the effect of chlorhexidine concentration on the biocorrosion behavior of Ti6Al4V for dental implants

Corrosion of dental implants is one of the most critical factors in the failure of implant treatments. Generally, corrosion depends on the type of material used in implants and the chemical composition of the oral environment. Due to the antibacterial activities, mouthwashes and chlorhexidine gels are often used after implant surgery. Ti6Al4V is commonly used in manufacturing dental implants. The present study aims to investigate the corrosion behavior of the Ti6Al4V alloy under different concentrations of chlorhexidine (0.12%, 0.2%,and 2%) during 2- and 24-h immersion. This way corrosion may be minimized while obtaining an antibacterial environment around the implant. In this regard, the electrochemical behavior of the specimens was investigated using polarization and impedance tests, and then their morphology, cross-section and nano-tribological behavior were evaluated using atomic force microscopy, scanning electron microscopy, energy dispersive x-ray spectroscopy, and nano-scratch test. The results show that using chlorhexidine solution with a concentration of 0.12% could yield a lower corrosion rate and material loss after implant surgery. RESEARCH HIGHLIGHTS: Open circuit potential values increase with immersion time, which suggests multistage passivation of the surface during immersion in chlorhexidine. Specimens in 0.12% chlorhexidine show improved thermodynamic corrosion resistance. Nano-scratch testing demonstrates higher scratch resistance for specimens in 0.12% chlorhexidine solution after 2-h immersion. Higher chlorhexidine concentration than 0.12% and longer immersion times decrease the resistance of the formed passive layer.

Evaluation of Corrosive Properties of Hafnium Nitride Coating Over Titanium Screws: An In Vitro Study

Background Varied surface coatings have been studied time and again in medical sciences. Whether general or dental, studying the performance of coatings aims to assess their potential to improve the durability and longevity of titanium implants, thereby advancing implant technology for enhanced patient outcomes. Various analytical techniques are utilized to assess the performance of the coating, providing insights into its effectiveness in preventing corrosion. The findings of this evaluation will contribute to our understanding of corrosion mitigation strategies for titanium implants and pave the way for the development of more durable implant materials. This article aims to evaluate the corrosion resistance of an innovative metal compound coating applied over titanium implants.  Materials and methods In this study, a total of 20 medical-grade, commercially pure titanium screws were collected. The dimensions of the titanium screws were 2mm x 7mm. Around 10 of these commercially pure titanium screw samples were used as the control group. Hafnium nitride (HfN) (0.1 M) was mixed with 100% ethanol and stirred using a glass rod for about 48 hours. Then 10 of the implant screw samples were immersed in the prepared sol and sintered at 400o C for two hours. The HfN-coated samples were then used as the test group. The corrosion resistance of both groups was tested using electrochemical impedance spectroscopy and potentiodynamic polarization studies. The Nyquist, Bode impedance, and Bode phase angle plots were obtained and studied.  Results Using the Stern-Geary equation, the corrosion current density was calculated. On analysis, these values indicated that the higher impedance in HfN-coated titanium screws showed higher mean corrosion potential (Ecorr = -0.452 V) and corrosion current density ( icorr = 0.0354 μA/cm2) than the uncoated titanium screws.  Conclusion It was concluded that the corrosion properties of HfN-coated titanium screws had higher impedance and consequently the highest corrosion resistance. This thereby provides a promising scope for further research of this novel metal coating for use in the biomedical sectors, specifically for dental implants.

The contribution of metal allergy to the failure of metal alloy implants, with special reference to titanium: Current knowledge and controversies

After almost three-quarters of a century during which contact dermatologists have often struggled to comprehend the relationship between metal allergy and failure of metal-alloy containing implant, it is possible to say that a relationship does exist, particularly for cobalt and chromium, but also for nickel. There is still debate as to whether allergy develops as a consequent of failure but thenceforth contributes to it, or whether sensitisation starts first and induces failure secondarily-opinion probably favours the first. Metal-on-polypropylene articulations were associated with few metal allergic problems but now are less favoured by orthopaedists due to plastic wear products causing osteolysis and pseudotumour formation through local inflammation. New metal alloys are regularly being introduced such that interested dermatologists need to stay on top of the situation. The jury is still out as to whether the recent favouring of titanium-containing alloys will confirm them to be more inert allergenically. Case reports do show some clinical reactions to titanium-containing implants and patch test series have inferred sometimes quite a high background rate of allergy, but interpretation must be tempered by the awareness that titanium salts on patch testing have a tendency to cause irritant reactions. Blood monitoring of metal ion values is now recommended in certain situations after joint replacement and increasing levels may be an indication that allergy with joint failure can develop, in which case patch testing is indicated, and suggested series are available. Predictive patch testing, whilst generally not recommended in the past, has been introduced into some protocols often by non-dermatologists, such that it is now needed for temporo-mandibular joint and Nuss bar insertion, and it can be anticipated that this may become more commonplace in the future. One of the major current deficits for patch testers is standardised guidance on which preparation or preparations to use for suspected titanium allergy. One suggestion is 0.5% titanium sulphate in petrolatum, though experience in at least one centre suggests the use of a battery of titanium salts might be desirable.

Influence of titanium nanoscale surface roughness on fibrinogen and albumin protein adsorption kinetics and platelet responses

Biomaterials with nanoscale topography have been increasingly investigated for medical device applications to improve tissue-material interactions. This study assessed the impact of nanoengineered titanium surface domain sizes on early biological responses that can significantly affect tissue interactions. Nanostructured titanium coatings with distinct nanoscale surface roughness were deposited on quartz crystal microbalance with dissipation (QCM-D) sensors by physical vapor deposition. Physico-chemical characterization was conducted to assess nanoscale surface roughness, nano-topographical morphology, wettability, and atomic composition. The results demonstrated increased projected surface area and hydrophilicity with increasing nanoscale surface roughness. The adsorption properties of albumin and fibrinogen, two major plasma proteins that readily encounter implanted surfaces, on the nanostructured surfaces were measured using QCM-D. Significant differences in the amounts and viscoelastic properties of adsorbed proteins were observed, dependent on the surface roughness, protein type, protein concentration, and protein binding affinity. The impact of protein adsorption on subsequent biological responses was also examined using qualitative and quantitative in vitro evaluation of human platelet adhesion, aggregation, and activation. Qualitative platelet morphology assessment indicated increased platelet activation/aggregation on titanium surfaces with increased roughness. These data suggest that nanoscale differences in titanium surface roughness influence biological responses that may affect implant integration.

Virgin Powder for Cold Spray Processing

Gas-atomization is extensively used to produce metallic feedstock powders for additive manufacturing processes, including gas dynamic cold spray processing. This work explores the potential utility of on-demand recycled titanium scrap feedstock powder as a viable substitute for virgin powder sources. Three recycled titanium powders were atomized from different battlefield scrap sources using a mobile foundry developed by MolyWorks Materials Corporation. Recycled titanium alloy powders were compared against virgin Ti-6Al-4V powder to verify there were no significant variations between the recycled and virgin materials. Powder characterization methods included chemical analysis, particle size distribution analysis, scanning electron microscopy (SEM), Karl Fischer (KF) titration moisture content analysis, X-ray diffraction (XRD) phase analysis, microparticle compression testing (MCT), and nanoindentation. Results indicate that recycled titanium powder provides a viable alternative to virgin titanium alloy powders without compromising mechanical capabilities, microstructural features, or ASTM-specified composition and impurity standards. The results of this work will be used to aid future research efforts that will focus on optimizing cold spray parameters to maximize coating density, mechanical strength, and hardness of recycled titanium feedstock powders. "Cold spray" presents opportunities to enhance the sustainability of titanium component production through the utilization of recycled feedstock powder, mitigating issues of long lead times and high waste associated with the use of conventional virgin feedstock.

Effectiveness of strontium/silver-based titanium surface coatings in improving antibacterial and osteogenic implant characteristics: a systematic review of in-vitro studies

Introduction: Due to the high incidence of implant failures, dual functionalization of titanium surfaces with antibacterial and osteogenic agents, like silver (Ag) and strontium (Sr), has gained significant attention in recent years. However, so far, the combined antibacterial and osteoinductive effectiveness of Ag/Sr-based titanium surface coatings has only been analyzed in individual studies. Methods: This systematic review aims to evaluate the existing scientific literature regarding the PICOS question "Does dual incorporation of strontium/silver enhances the osteogenic and anti-bacterial characteristics of Ti surfaces in vitro?". As a result of a web-based search adhering to the PRISMA Guidelines using three electronic databases (PubMed, Scopus, and Web of Science) until March 31, 2023, a total of 69 publications were identified as potentially relevant and 17 of which were considered appropriate for inclusion into this review. Results and Discussion: In all included publications, the use of Sr/Ag combination showed enhanced osteogenic and antibacterial effects, either alone or in combination with other agents. Moreover, the combination of Sr and Ag shows potential to synergistically enhance these effects. Nevertheless, further studies need to validate these findings under clinically more relevant conditions and evaluate the mechanism of antimicrobial and osteogenic activity of Sr/Ag combination.

Titanium-Doped Diamond-like Carbon Layers as a Promising Coating for Joint Replacements Supporting Osteogenic Differentiation of Mesenchymal Stem Cells

Diamond-like carbon (DLC) layers are known for their high corrosion and wear resistance, low friction, and high biocompatibility. However, it is often necessary to dope DLC layers with additional chemical elements to strengthen their adhesion to the substrate. Ti-DLC layers (doped with 0.4, 2.1, 3.7, 6.6, and 12.8 at.% of Ti) were prepared by dual pulsed laser deposition, and pure DLC, glass, and polystyrene (PS) were used as controls. In vitro cell-material interactions were investigated with an emphasis on cell adhesion, proliferation, and osteogenic differentiation. We observed slightly increasing roughness and contact angle and decreasing surface free energy on Ti-DLC layers with increasing Ti content. Three-week biological experiments were performed using adipose tissue-derived stem cells (ADSCs) and bone marrow mesenchymal stem cells (bmMSCs) in vitro. The cell proliferation activity was similar or slightly higher on the Ti-doped materials than on glass and PS. Osteogenic cell differentiation on all materials was proved by collagen and osteocalcin production, ALP activity, and Ca deposition. The bmMSCs exhibited greater initial proliferation potential and an earlier onset of osteogenic differentiation than the ADSCs. The ADSCs showed a slightly higher formation of focal adhesions, higher metabolic activity, and Ca deposition with increasing Ti content.

Investigation into the Three-Stage Formation of Micro-Channels with Ultra-Thin Titanium Sheets Used for Proton-Exchange Membrane Fuel Cell Bipolar Plates

Titanium has a low density and high corrosion resistance. In order to achieve the goal of a lightweight material, and to extend the normal working hour of proton-exchange membrane fuel cells (PEMFCs), ultra-thin titanium plates were chosen to manufacture the key components-bipolar plates (BPs). For the purpose of overcoming the challenges of manufacturing with a large depth to width ratio, a multi-stage formation process was established with characteristics such as high efficiency and a lower price. In this study, the process parameters were examined through an experimental approach. The outcomes show that the channel formed by multistage forming is deeper than that formed by single-stage forming under the same displacement conditions. To achieve greater flow depths, it is recommended to increase the displacements as much as possible during both the first- and second-stage forming processes. The implementation of three-stage forming can effectively reduce the maximum thinning rates within flow channels while improving the overall deformation uniformity. This method deviates from traditional one-stage loading processes by adopting multi-stage loading instead. By employing appropriate mold designs, material deformation and flow can be enhanced throughout gradual loading processes, thereby preventing strain concentration and enhancing the ultimate formation height accuracy within micro-flow channels. Consequently, the proposed three-stage forming process proves highly appropriate for the mass production of BPs utilizing titanium plates.

Advancements in incorporating metal ions onto the surface of biomedical titanium and its alloys via micro-arc oxidation: a research review

The incorporation of biologically active metallic elements into nano/micron-scale coatings through micro-arc oxidation (MAO) shows significant potential in enhancing the biological characteristics and functionality of titanium-based materials. By introducing diverse metal ions onto titanium implant surfaces, not only can their antibacterial, anti-inflammatory and corrosion resistance properties be heightened, but it also promotes vascular growth and facilitates the formation of new bone tissue. This review provides a thorough examination of recent advancements in this field, covering the characteristics of commonly used metal ions and their associated preparation parameters. It also highlights the diverse applications of specific metal ions in enhancing osteogenesis, angiogenesis, antibacterial efficacy, anti-inflammatory and corrosion resistance properties of titanium implants. Furthermore, the review discusses challenges faced and future prospects in this promising area of research. In conclusion, the synergistic approach of micro-arc oxidation and metal ion doping demonstrates substantial promise in advancing the effectiveness of biomedical titanium and its alloys, promising improved outcomes in medical implant applications.

Anticorrosion and Antimicrobial Tannic Acid-Functionalized Ti-Metallic Glass Ribbons for Dental Abutment

In this study, a recently reported Ti-based metallic glass (MG), without any toxic element, but with a significant amount of metalloid (Si-Ge-B, 18 atom %) and minor soft element (Sn, 2 atom %), was produced in ribbon form using conventional single-roller melt-spinning. The produced Ti60Zr20Si8Ge7B3Sn2 ribbons were investigated by differential scanning calorimetry and X-ray diffraction to confirm their amorphous structure, and their corrosion properties were further investigated by open-circuit potential and cyclic polarization tests. The ribbon's surface was functionalized by tannic acid, a natural plant-based polyphenol, to enhance its performance in terms of corrosion prevention and antimicrobial efficacy. These properties can potentially be exploited in the premucosal parts of dental implants (abutments). The Folin and Ciocalteu test was used for the quantification of tannic acid (TA) grafted on the ribbon surface and of its redox activity. Fluorescent microscopy and ζ-potential measurements were used to confirm the presence of TA on the surfaces of the ribbons. The cytocompatibility evaluation (indirect and direct) of TA-functionalized Ti60Zr20Si8Ge7B3Sn2 MG ribbons toward primary human gingival fibroblast demonstrated that no significant differences in cell viability were detected between the functionalized and as-produced (control) MG ribbons. Finally, the antibacterial investigation of TA-functionalized samples against Staphylococcus aureus demonstrated the specimens' antimicrobial properties, shown by scanning electron microscopy images after 24 h, presenting a few single colonies remaining on their surfaces. The thickness of bacterial aggregations (biofilm-like) that were formed on the surface of the as-produced samples reduced from 3.5 to 1.5 μm.

A method for crystallographic mapping of an alpha-beta titanium alloy with nanometre resolution using scanning precession electron diffraction and open-source software libraries

An approach for the crystallographic mapping of two-phase alloys on the nanoscale using a combination of scanned precession electron diffraction and open-source python libraries is introduced in this paper. This method is demonstrated using the example of a two-phase α/β titanium alloy. The data were recorded using a direct electron detector to collect the patterns, and recently developed algorithms to perform automated indexing and analyse the crystallography from the results. Very high-quality mapping is achieved at a 3 nm step size. The results show the expected Burgers orientation relationships between the α laths and β matrix, as well as the expected misorientations between α laths. A minor issue was found that one area was affected by 180° ambiguities in indexing occur due to this area being aligned too close to a zone axis of the α with twofold projection symmetry (not present in 3D) in the zero-order Laue Zone, and this should be avoided in data acquisition in the future. Nevertheless, this study demonstrates a good workflow for the analysis of nanocrystalline two- or multi-phase materials, which will be of widespread use in analysing two-phase titanium and other systems and how they evolve as a function of thermomechanical treatments.

Polymer-Metal Bilayer with Alkoxy Groups for Antibacterial Improvement

Many bio-applicable materials, medical devices, and prosthetics combine both polymer and metal components to benefit from their complementary properties. This goal is normally achieved by their mechanical bonding or casting only. Here, we report an alternative easy method for the chemical grafting of a polymer on the surfaces of a metal or metal alloys using alkoxy amine salt as a coupling agent. The surface morphology of the created composites was studied by various microscopy methods, and their surface area and porosity were determined by adsorption/desorption nitrogen isotherms. The surface chemical composition was also examined by various spectroscopy techniques and electrokinetic analysis. The distribution of elements on the surface was determined, and the successful bonding of the metal/alloys on one side with the polymer on the other by alkoxy amine was confirmed. The composites show significantly increased hydrophilicity, reliable chemical stability of the bonding, even interaction with solvent for thirty cycles, and up to 95% less bacterial adhesion for the modified samples in comparison with pristine samples, i.e., characteristics that are promising for their application in the biomedical field, such as for implants, prosthetics, etc. All this uses universal, two-step procedures with minimal use of energy and the possibility of production on a mass scale.

Concentrations of Cobalt, Chromium and Titanium and Immunological Changes after Primary Total Knee Arthroplasty-A Cohort Study with an 18-Year Follow-Up

Background: Total knee arthroplasty (TKA) generates elevated metal ion concentrations, but long-term changes in the concentrations of cobalt (Co), chromium (Cr) and titanium (Ti) after primary TKA and potential subsequent immune system activation-not limited to the joint but systemically-are not known. Patients and Methods: We conducted a cohort study on 26 patients with TKA (19 women; 16 with metal-backed and 10 with all-polyethylene tibial components) 18.3 years (min. 16.7, max. 20.5) after index TKA. A total of 69% of patients additionally underwent subsequent arthroplasty of the contralateral knee or either hip after the index surgery. Blood samples were analysed by inductively coupled plasma-mass spectrometry, and leukocytes were characterised by flow cytometry. Patients were clinically assessed using the Knee Society score and by plain radiography of the knee. Results: The median metal ion concentrations were 0.7 (0.1-13.0) µg/L for Co, 0.9 (0.4-5.0) µg/L for Cr, and 1.0 (0.2-13.0) µg/L for Ti. There was no relevant difference in systemic metal ion concentrations between patients exposed to single and multiple arthroplasties. The absolute count and proportion of CD3+CD4+CD8+ T cells was inversely correlated with both Co (rho -0.55, p = 0.003) and Cr concentrations (rho -0.59, p = 0.001). Conclusions: Between the first and second decades after primary TKA, in most patients, the concentrations of Co, Cr and Ti in blood samples were below the thresholds that are considered alarming. The negative correlation of Co and Cr concentrations with a subset of lymphocytes that commonly increases during immune activation is reassuring. This represents a worst-case scenario, underscoring that the investigated metal ions remain within reasonable ranges, even after additional hardware exposure.

Corrosion of an Additively Manufactured Ti6Al4V Alloy in Saline and Acidic Media

The present work aims to provide corrosion performance data for an additively manufactured Ti6Al4V alloy in saline and polluted environments. The as-received additively manufactured material underwent heat treatment at 850 °C for 3 h to transform the acicular α' microstructure into a lamellar α microstructure. Comparative corrosion assessments were conducted between the heat-treated substrates, the as-received condition, and a conventionally mill-annealed alloy. Potentiodynamic polarization experiments were carried out in saline (3.5 wt.% NaCl) and acid aqueous media ((NH4)2SO4 containing Harrison's solution). The corrosion performance of additively manufactured substrates matched or surpassed that of the conventional alloy in Harrison's solutions while remaining inferior in saline medium, despite forming a thicker passive film. Overall, the XY plane showed better corrosion performance, particularly after the elimination of the acicular α' martensite by the applied heat treatment. The results also suggested that the presence of the coarse β phase was beneficial in 3.5 wt.% NaCl solution and detrimental in Harrison's solutions, more so in acidified and fluorinated conditions.

Shear bond strength of the ceramic veneer to additively manufactured titanium

OBJECTIVES

The objective of this in vitro study was to evaluate the shear bond strength between the ceramic veneer and additively manufactured titanium with different surface treatments, and to compare with milled titanium. Also, to characterize the surface and the presence of an α-case layer of additively manufactured and milled titanium.

MATERIAL AND METHODS

Sixty additively manufactured titanium grade 23, and 20 milled titanium grade 4 cylindrical specimens were divided into four groups based on surface treatments, air-particle abrasion and grinding. After ceramic veneering half of each group were thermocycled. The bond strength was analyzed using a shear bond strength test. The surfaces were analyzed using interferometry and scanning electron microscopy.

RESULTS

The grinding procedure and air-particle abrading pressure had no significant effect on the shear bond strength (p = .264 and p = .344). Thermocycling showed a tendency towards an effect but not significant (p = .052). The group with the highest air-abrading pressure showed the highest surface roughness. No presence of an α-case layer was detected in any of the groups.

CONCLUSION

Additively manufactured titanium grade 23 may be veneered with ceramics without prior grinding of the surfaces.

Fabrication and evaluation of silver modified micro/nano structured titanium implant

In order to enhance the antibacterial property of titanium implant without inducing obvious cytotoxicity, the combination of Ag nanolayer and micro/nano surface structure was conducted by magnetron sputtering and hot-alkali treatment in this study. A series of specimens (AH-Ti, AH-Ti/Ag0.25, AH-Ti/Ag1, AH-Ti/Ag2, and AH-Ti/Ag5) were prepared with different sputtering durations (0 min, 0.25 min, 1 min, 2 min, 5 min), respectively, all realizing long-term release of Ag+. In vitro experiments indicated that AH-Ti/Ag1 group possessed good cytocompatibility, nice osteogenic ability, and excellent antibacterial efficiency as well. In addition, AH-Ti/Ag0.25 showed good biocompatibility, while the reduction of S.aureus (78.5%) was not enough compared with AH-Ti/Ag1. Although the AH-Ti/Ag2 and AH-Ti/Ag5 group showed superior antibacterial activity, their obvious cytotoxicity caused low ALP and mineralization level. Therefore, the design of suitable Ag nanolayer coating combined with micro/nano surface structure (AH-Ti/Ag1) might be a promising strategy to enhance osteogenic property and maintain excellent antibacterial ability at the same time.

Influence of Addition of Ti Particles and Processing Condition on Microstructure and Properties of Selectively Laser-Melted Invar 36 Alloy

Invar 36 exhibits extremely low thermal expansion coefficients at low temperatures but also low yield strength (YS), which greatly restricts its application as a structural material. In this study, a small fraction of pure titanium powder particles was added into Invar 36 by powder mixing and selective laser melting (SLM) with the aim of further improving tensile strengths of Invar 36. It was found that increased laser power led to increased grain size and to slight decrease in YS in Invar 36. During SLM, amorphous SiO2 nanoparticles were formed and homogeneously distributed in Invar 36. With the addition of 2 at% Ti powder particles, grains became larger and the crystallographic texture along <001> and <111> increased to some extent. Moreover, the bottom of solidified melt pools was segregated with Ti while the matrix was homogeneously decorated by a great number of nano-sized spherical Ti2O3 particles. These particles were found to have effectively impeded dislocation motion during plastic deformation, leading to significant improvement in 0.2% YS and ultimate tensile strength. The above precipitation led to consumption of a small amount of Ni from the matrix, which caused a minor compromise in thermal expansion properties. Nonetheless, the newly synthesized Invar 36-Ti alloy still exhibits low thermal expansion coefficients at low temperatures and remarkably enhanced tensile strengths.

Characterization of aTiO2 surfaces functionalized with CAP-p15 peptide

Functionalization of Titanium implants using adequate organic molecules is a proposed method to accelerate the osteointegration process, which relates to topographical, chemical, mechanical, and physical features. This study aimed to assess the potential of a peptide derived from cementum attachment protein (CAP-p15) adsorbed onto aTiO2 surfaces to promote the deposition of calcium phosphate (CaP) minerals and its impact on the adhesion and viability of human periodontal ligament cells (hPDLCs). aTiO2 surfaces were synthesized by magnetron sputtering technique. The CAP-p15 peptide was physically attached to aTiO2 surfaces and characterized by atomic force microscopy, fluorescence microscopy, and water contact angle measurement. We performed in vitro calcium phosphate nucleation assays using an artificial saliva solution (pH 7.4) to simulate the oral environment. morphological and chemical characterization of the deposits were evaluated by scanning electronic microscopy (SEM) and spectroscopy molecular techniques (Raman Spectroscopy, ATR-FTIR). The aTiO2 surfaces biofunctionalized with CAP-p15 were also analyzed for hPDLCs attachment, proliferation, and in vitro scratch-healing assay. The results let us see that the homogeneous amorphous titanium oxide coating was 70 nanometers thick. The CAP-p15 (1 μg/mL) displayed the ability to adsorb onto the aTiO2 surface, increasing the roughness and maintaining the hydrophilicity of the aTiO2 surfaces. The physical adsorption of CAP-p15 onto the aTiO2 surfaces promoted the precipitation of a uniform layer of crystals with a flake-like morphology and a Ca/P ratio of 1.79. According to spectroscopy molecular analysis, these crystalline deposits correspond to carbonated hydroxyapatite. Regarding cell behavior, the biofunctionalized aTiO2 surfaces improved the adhesion of hPDLCs after 24 h of cell culture, achieving 3.4-fold when compared to pristine surfaces. Moreover, there was an increase in cell proliferation and cell migration processes. Physical adsorption of CAP-p15 onto aTiO2 surfaces enhanced the formation of carbonate hydroxyapatite crystals and promoted the proliferation and migration of human periodontal ligament-derived cells in in vitro studies. This experimental model using the novel bioactive peptide CAP-p15 could be used as an alternative to increasing the osseointegration process of implants.

Nonthermal Plasma Synthesis of Metallic Ti Nanocrystals

Nanoscale metallic titanium (Ti) offers unique energetic and biocompatible characteristics for the aerospace and biomedical industries. A rapid and sustainable method to form purified Ti nanocrystals is still in demand due to their high oxygen affinity. Herein, we report the production of highly purified Ti nanoparticles with a nonequilibrium face center cubic (FCC) structure from titanium tetrachloride (TiCl4) via a capacitively coupled plasma (CCP) route. Furthermore, we demonstrate a secondary H2 treatment plasma as an effective strategy to improve the air stability of a thin layer of nanoparticles by further removal of chlorine from the particle surface. Hexagonal and cubic-shaped Ti nanocrystals of high purity were maintained in the air after the secondary H2 plasma treatment. The FCC phase potentially originates from small-sized grains in the initial stage of nucleation inside the plasma environment, which is revealed by a size evolution study with variations of plasma power input.

10 μm-Level TiNb2 O7 Secondary Particles for Fast-Charging Lithium-Ion Batteries

TiNb2 O7 with Wadsley-Roth phase delivers double theoretical specific capacity and similar working potential in comparison to spinel Li4 Ti5 O12 , the commercial high-rate anode material, and thus can enable much higher energy density of lithium-ion batteries. However, the inter-particle resistance within the high-mass-loading TiNb2 O7 electrode would impede the capacity release for practical application, especially under fast-charging conditions. Herein, 10-20 μm-size carbon-coated TiNb2 O7 secondary particle (SP-TiNb2 O7 ) consisting of initial micro-scale TiNb2 O7 particles (MP-TiNb2 O7 ) was fabricated. The high crystallinity of active material could enable fast-charge diffusion and electrochemical reaction rate within particles, and the small number of stacking layers of SP-TiNb2 O7 could reduce the large inter-particle resistance that regular particle electrode often possess and achieve high compaction density of electrodes with high mass loading. The investigation on materials structure and electrochemical reaction kinetics verified the advances of the as-fabricated SP-TiNb2 O7 in achieving superior electrochemical performance. The SP-TiNb2 O7 exhibited high reversible capacity of 292.7 mAh g-1 in the potential range of 1-3 V (Li+ /Li) at 0.1 C, delivering high-capacity release of 94.3 %, and high capacity retention of 86 % at 0.5 C for 250 cycles in half cell configuration. Particularly, the advances of such an anode were verified in practical 5 Ah-level laminated full pouch cell. The as-assembled LiFePO4 ||TiNb2 O7 full cell exhibited a high capacity of 5.08 Ah at high charging rate of 6 C (77.9 % of that at 0.2 C of 6.52 Ah), as well as an ultralow capacity decay rate of 0.0352 % for 250 cycles at 1 C, suggesting the great potential for practical fast-charging lithium-ion batteries.

On-Chip Modification of Titanium Electrothermal Characteristics by Joule Heating: Application to Terahertz Microbolometer

This study demonstrates the conversion of metallic titanium (Ti) to titanium oxide just by conducting electrical current through Ti thin film in vacuum and increasing the temperature by Joule heating. This led to the improvement of electrical and thermal properties of a microbolometer. A microbolometer with an integrated Ti thermistor and heater width of 2.7 µm and a length of 50 µm was fabricated for the current study. Constant-voltage stresses were applied to the thermistor wire to observe the effect of the Joule heating on its properties. Thermistor resistance ~14 times the initial resistance was observed owing to the heating. A negative large temperature coefficient of resistance (TCR) of -0.32%/K was also observed owing to the treatment, leading to an improved responsivity of ~4.5 times from devices with untreated Ti thermistors. However, this does not improve the noise equivalent power (NEP), due to the increased flicker noise. Microstructural analyses with transmission electron microscopy (TEM), transmission electron diffraction (TED) and energy dispersive X-ray (EDX) confirm the formation of a titanium oxide (TiOx) semiconducting phase on the Ti phase (~85% purity) deposited initially, further to the heating. Formation of TiOx during annealing could minimize the narrow width effect, which we reported previously in thin metal wires, leading to enhancement of responsivity.

Bacterial Surface Appendages Modulate the Antimicrobial Activity Induced by Nanoflake Surfaces on Titanium

Bioinspired nanotopography is a promising approach to generate antimicrobial surfaces to combat implant-associated infection. Despite efforts to develop bactericidal 1D structures, the antibacterial capacity of 2D structures and their mechanism of action remains uncertain. Here, hydrothermal synthesis is utilized to generate two 2D nanoflake surfaces on titanium (Ti) substrates and investigate the physiological effects of nanoflakes on bacteria. The nanoflakes impair the attachment and growth of Escherichia coli and trigger the accumulation of intracellular reactive oxygen species (ROS), potentially contributing to the killing of adherent bacteria. E. coli surface appendages type-1 fimbriae and flagella are not implicated in the nanoflake-mediated modulation of bacterial attachment but do influence the bactericidal effects of nanoflakes. An E. coli ΔfimA mutant lacking type-1 fimbriae is more susceptible to the bactericidal effects of nanoflakes than the parent strain, while E. coli cells lacking flagella (ΔfliC) are more resistant. The results suggest that type-1 fimbriae confer a cushioning effect that protects bacteria upon initial contact with the nanoflake surface, while flagella-mediated motility can lead to elevated membrane abrasion. This finding offers a better understanding of the antibacterial properties of nanoflake structures that can be applied to the design of antimicrobial surfaces for future medical applications.