Short term exposure to titanium, aluminum and vanadium (Ti 6Al 4V) alloy powder drastically affects behavior and antioxidant metabolites in vital organs of male albino mice

Harnessing 3D printed highly porous Ti-6Al-4V scaffolds coated with graphene oxide to promote osteogenesis

Bone tissue engineering (BTE) strategies have been developed to address challenges in orthopedic and dental therapy by expediting osseointegration and new bone formation. In this study, we developed irregular porous Ti-6Al-4V scaffolds coated with reduced graphene oxide (rGO), specifically rGO-pTi, and investigated their ability to stimulate osseointegration in vivo. The rGO-pTi scaffolds exhibited unique irregular micropores and high hydrophilicity, facilitating protein adsorption and cell growth. In vitro assays revealed that the rGO-pTi scaffolds increased alkaline phosphatase (ALP) activity, mineralization nodule formation, and osteogenic gene upregulation in MC3T3-E1 preosteoblasts. Moreover, in vivo transplantation of rGO-pTi scaffolds in rabbit calvarial bone defects showed improved bone matrix formation and osseointegration without hemorrhage. These findings highlight the potential of combining rGO with irregular micropores as a promising BTE scaffold for bone regeneration.

Advances in Multifunctional Bioactive Coatings for Metallic Bone Implants

To fix the bone in orthopedics, it is almost always necessary to use implants. Metals provide the needed physical and mechanical properties for load-bearing applications. Although widely used as biomedical materials for the replacement of hard tissue, metallic implants still confront challenges, among which the foremost is their low biocompatibility. Some of them also suffer from excessive wear, low corrosion resistance, infections and shielding stress. To address these issues, various coatings have been applied to enhance their in vitro and in vivo performance. When merged with the beneficial properties of various bio-ceramic or polymer coatings remarkable bioactive, osteogenic, antibacterial, or biodegradable composite implants can be created. In this review, bioactive and high-performance coatings for metallic bone implants are systematically reviewed and their biocompatibility is discussed. Updates in coating materials and formulations for metallic implants, as well as their production routes, have been provided. The ways of improving the bioactive coating performance by incorporating bioactive moieties such as growth factors, osteogenic factors, immunomodulatory factors, antibiotics, or other drugs that are locally released in a controlled manner have also been addressed.

Varying Doses of Rare-Earth-Metal-Based Neodymium Zirconate Zinc Sulfide Nanocomposite Disrupt Blood and Serum Parameters, as well as Markers of Oxidative Stress in the Selected Organs of Albino Mice

Despite extensive industrial use, the biocompatibility of nanocomposites has not been extensively explored. The present study was designed to report the effect of variable doses of a newly synthesized nanocomposite, Neodymium Zirconate Zinc Sulfide, on selective serum and complete blood count parameters and on the oxidative stress markers from the vital organs of albino mice. Albino mice (C57BL/6 strain, 5 weeks old) of both sexes were orally treated for 11 days, either with 10 mg (low dose) or 20 mg/mL saline/kg body weight (high dose) of Neodymium Zirconate Zinc Sulfide nanocomposite. A control group that was not treated with the nanocomposite but with saline solution was also maintained. Data analysis revealed that high-dose nanocomposite-treated male mice had significantly reduced hemoglobin concentration as compared to the control males. Female mice treated with both doses of nanocomposite had higher serum triglyceride levels than controls. High-dose-treated female mice had elevated serum cholesterol concentration compared to their saline-treated controls. Oxidative stress marker analysis from selected organs indicated that concentrations of malonaldehyde (MDA) in the kidney and liver, Superoxide dismutase (SOD) levels in the brain and catalase in the kidney of male mice treated with the nanocomposite were significantly higher than in the control group, whereas SOD in the heart, MDA in the heart and kidney and catalase levels in the kidney were significantly disrupted in female mice compared to their respective controls.

Recent Advancements in Materials and Coatings for Biomedical Implants

Metallic materials such as stainless steel (SS), titanium (Ti), magnesium (Mg) alloys, and cobalt-chromium (Co-Cr) alloys are widely used as biomaterials for implant applications. Metallic implants sometimes fail in surgeries due to inadequate biocompatibility, faster degradation rate (Mg-based alloys), inflammatory response, infections, inertness (SS, Ti, and Co-Cr alloys), lower corrosion resistance, elastic modulus mismatch, excessive wear, and shielding stress. Therefore, to address this problem, it is necessary to develop a method to improve the biofunctionalization of metallic implant surfaces by changing the materials' surface and morphology without altering the mechanical properties of metallic implants. Among various methods, surface modification on metallic surfaces by applying coatings is an effective way to improve implant material performance. In this review, we discuss the recent developments in ceramics, polymers, and metallic materials used for implant applications. Their biocompatibility is also discussed. The recent trends in coatings for biomedical implants, applications, and their future directions were also discussed in detail.

Metallic Implants Used in Lumbar Interbody Fusion

Over the last decade, pedicle fixation systems have evolved and modifications in spinal fusion techniques have been developed to increase fusion rates and improve clinical outcomes after lumbar interbody fusion (LIF). Regarding materials used for screw and rod manufacturing, metals, especially titanium alloys, are the most popular resources. In the case of pedicle screws, that biomaterial can be also doped with hydroxyapatite, CaP, ECM, or tantalum. Other materials used for rod fabrication include cobalt-chromium alloys and nitinol (nickel-titanium alloy). In terms of mechanical properties, the ideal implant used in LIF should have high tensile and fatigue strength, Young's modulus similar to that of the bone, and should be 100% resistant to corrosion to avoid mechanical failures. On the other hand, a comprehensive understanding of cellular and molecular pathways is essential to identify preferable characteristics of implanted biomaterial to obtain fusion and avoid implant loosening. Implanted material elicits a biological response driven by immune cells at the site of insertion. These reactions are subdivided into innate (primary cellular response with no previous exposure) and adaptive (a specific type of reaction induced after earlier exposure to the antigen) and are responsible for wound healing, fusion, and also adverse reactions, i.e., hypersensitivity. The main purposes of this literature review are to summarize the physical and mechanical properties of metal alloys used for spinal instrumentation in LIF which include fatigue strength, Young's modulus, and corrosion resistance. Moreover, we also focused on describing biological response after their implantation into the human body. Our review paper is mainly focused on titanium, cobalt-chromium, nickel-titanium (nitinol), and stainless steel alloys.

Effect of Surface Tooling Techniques of Medical Titanium Implants on Bacterial Biofilm Formation In Vitro

The aim of this study was to assess the biofilm formation of Streptococcus mutans, Staphylococcus aureus, Enterococcus faecalis, and Escherichia coli on titanium implants with CAD-CAM tooling techniques. Twenty specimens of titanium were studied: Titanium grade 2 tooled with a Planmeca CAD-CAM milling device (TiGrade 2), Ti6Al4V grade 5 as it comes from CAD-DMLS device (computer aided design-direct metal laser sintering device) (TiGrade 5), Ti6Al4V grade 23 as it comes from a CAD-CAM milling device (TiGrade 23), and CAD-DMLS TiGrade 5 polished with an abrasive disc (TiGrade 5 polished). Bacterial adhesion on the implants was completed with and without saliva treatment to mimic both extraoral and intraoral surgical methods of implant placement. Five specimens/implant types were used in the bacterial adhesion experiments. Autoclaved implant specimens were placed in petri plates and immersed in saliva solution for 30 min at room temperature and then washed 3×with 1 ×PBS. Bacterial suspensions of each strain were made and added to the specimens after saliva treatment. Biofilm was allowed to form for 24 h at 37 °C and the adhered bacteria was calculated. Tooling techniques had an insignificant effect on the bacterial adhesion by all the bacterial strains studied. However, there was a significant difference in biofilm formation between the saliva-treated and non-saliva-treated implants. Saliva contamination enhanced S. mutans, S. aureus, and E. faecalis adhesion in all material types studied. S. aureus was found to be the most adherent strain in the saliva-treated group, whereas E. coli was the most adherent strain in the non-saliva-treated group. In conclusion, CAD-CAM tooling techniques have little effect on bacterial adhesion. Saliva coating enhances the biofilm formation; therefore, saliva contamination of the implant must be minimized during implant placement. Further extensive studies are needed to evaluate the effects of surface treatments of the titanium implant on soft tissue response and to prevent the factors causing implant infection and failure.

Toxicological assessment of nanocrystalline metal alloys with potential applications in the aeronautical field

The development of new candidate alloys with outstanding characteristics for their use in the aeronautical field is one of the main priorities for the sector. In this context, nanocrystaline (nc) alloys are considered relevant materials due to their special features, such as their exceptional physical and mechanical properties. However, another important point that needs to be considered with newly developed alloys is the potential toxicological impact that these materials may have in humans and other living organisms. The aim of this work was to perform a preliminary toxicological evaluation of three nc metal alloys (WCu, WAl and TiAl) in powder form produced by mechanical alloying, applying different in vitro assays, including a mix of W-Cu powders with standard grain size in the experiments to stablish comparisons. The effects of the direct exposure to powder suspensions and/or to their derived leachates were analysed in three model organisms representative of human and environmental exposures (the adenocarcinomic human alveolar basal epithelial cell line A549, the yeast Saccharomyces cerevisiae and the Gram negative bacterium Vibrio fischeri). Altogether, the results obtained provide new insights about the potential harmful effects of the selected nc alloys, showing that, from a toxicological perspective, nc TiAl is the safest candidate in the model organisms and conditions tested.

EIS Characterization of Ti Alloys in Relation to Alloying Additions of Ta

The increased popularity of Ti and its alloys as important biomaterials is driven by their low modulus, greater biocompatibility, and better corrosion resistance in comparison to traditional biomaterials, such as stainless steel and Co-Cr alloys. Ti alloys are successfully used in severe stress situations, such as Ti-6Al-4V, but this alloy is related to long-term health problems and, in response, different Ti alloys composed of non-toxic and non-allergic elements such as Nb, Zr, Mo, and Ta have been developed for biomedical applications. In this context, binary alloys of titanium and tantalum have been developed and are predicted to be potential products for medical purposes. More than this, today, novel biocompatible alloys such as high entropy alloys with Ti and Ta are considered for biomedical applications and therefore it is necessary to clarify the influence of tantalum on the behavior of the alloy. In this study, various Ti-xTa alloys (with x = 5, 15, 25, and 30) were characterized using different techniques. High-resolution maps of the materials' surfaces were generated by scanning tunneling microscopy (STM), and atom distribution maps were obtained by energy dispersive X-ray spectroscopy (EDS). A thorough output of chemical composition, and hence the crystallographic structure of the alloys, was identified by X-ray diffraction (XRD). Additionally, the electrochemical behavior of these Ti-Ta alloys was investigated by EIS in simulated body fluid at different potentials. The passive layer resistance increases with the potential due to the formation of the passive layer of TiO₂ and Ta₂O₅ and then decreases due to the dissolution processes through the passive film. Within the Ti-xTa alloys, Ti-25Ta demonstrates excellent passive layer and corrosion resistance properties, so it seems to be a promising product for metallic medical devices.

Silver-Releasing Micro-/Nanoporous Coating on Additively Manufactured Macroporous Ti-Ta-Nb-Zr Scaffolds with High Osseointegration and Antibacterial Properties

The two major problems of titanium alloy surface of bone/dental implants were the lack of native tissue integration and associated infection. To solve these problems, the development of self-defending implants with intrinsic osteogenic properties has been highlighted, in which titanium alloy surfaces of bone/dental implants are endowed with antibacterial property by silver (Ag) incorporated in biomaterials. In this study, we biofunctionalized the surface of selective laser melting (SLM) manufactured volume-porous Ti-Ta-Nb-Zr scaffolds by using plasma electrolytic oxidation (PEO) as a way to eliminate the peri-operative bacterial load and promote osseointegration. In the experiment, the PEO process operated with three different concentration (1, 1, and 2 g/L) of a AgNO3 solution. As a result, a titanium oxide coating embedded with calcium and phosphorous and Ag was formed by one-step PEO treatment, and a presence of HAp was detected by X-ray diffraction (XRD) and XPS. In addition, Ag ions were found to be released from the scaffolds for at least 28 days, resulting in an effective prevention of bacterial adhesion and a decrease of the number of planktonic bacteria, with no sign of cytotoxicity shown simultaneously. Highly porosity micropores were formed on the surface of scaffolds after oxidation, and the mechanical properties did not show any signs of change. Besides, a strong calcium deposition and osteoconductive effect were found on the surface of PEO-treated Ag scaffolds. To sum up, this study reveals the potential of PEO coatings to biofunctionalize SLM Ti-Ta-Nb-Zr scaffolds with antibacterial agents. The biomaterials developed here, therefore, exploit the biofunctionalized behavior of Ag to offer strong antibacterial behavior and osteogenic promotion without cytotoxicity of Ag against mammalian cells.

Exposure to variable doses of nickel oxide nanoparticles disturbs serum biochemical parameters and oxidative stress biomarkers from vital organs of albino mice in a sex-specific manner

INTRODUCTION

This study was designed to report the biological effect of nickel oxide nanoparticles (NiO NPs) in albino mice.

MATERIAL AND METHODS

Five weeks old albino mice of both sex were intraperitoneally injected either with 20 mg (low dose) or 50 mg/mL saline/kg body weight (high dose) of NiO NPs for 14 days. Saline-treated controls were maintained in parallel. Complete blood count, selected serum biochemical parameters and oxidative stress biomarkers from vital organs were determined in all subjects.

RESULTS

Male mice treated with NiO NPS had increased blood urea nitrogen, elevated superoxide dismutase (SOD) in liver elevated MDA in liver, kidney and heart and reduced catalase activity in heart and kidney. Female mice treated with NiO NPs had significantly reduced serum albumin and total proteins, SOD in lungs and elevated MDA in liver.

DISCUSSION

We are reporting that intraperitoneal injections of NiO NPs for 14 days drastically affect blood serum parameters and oxidative stress biomarkers from vital organs of albino mice.

CONCLUSION

Toxic effects of NiO NPs were dose and sex dependent and they were more pronounced at higher dose and in male mice.

Are Titania Photocatalysts and Titanium Implants Safe? Review on the Toxicity of Titanium Compounds

Titanium and its compounds are broadly used in both industrial and domestic products, including jet engines, missiles, prostheses, implants, pigments, cosmetics, food, and photocatalysts for environmental purification and solar energy conversion. Although titanium/titania-containing materials are usually safe for human, animals and environment, increasing concerns on their negative impacts have been postulated. Accordingly, this review covers current knowledge on the toxicity of titania and titanium, in which the behaviour, bioavailability, mechanisms of action, and environmental impacts have been discussed in detail, considering both light and dark conditions. Consequently, the following conclusions have been drawn: (i) titania photocatalysts rarely cause health and environmental problems; (ii) despite the lack of proof, the possible carcinogenicity of titania powders to humans is considered by some authorities; (iii) titanium alloys, commonly applied as implant materials, possess a relatively low health risk; (iv) titania microparticles are less toxic than nanoparticles, independent of the means of exposure; (v) excessive accumulation of titanium in the environment cannot be ignored; (vi) titanium/titania-containing products should be clearly marked with health warning labels, especially for pregnant women and young children; (vi) a key knowledge gap is the lack of comprehensive data about the environmental content and the influence of titania/titanium on biodiversity and the ecological functioning of terrestrial and aquatic ecosystems.

Physiochemical and biological evaluation of SLM-manufactured Ti-10Ta-2Nb-2Zr alloy for biomedical implant applications

Titanium alloys, such as Ti-10Ta-2Nb-2Zr (TTNZ), are promising biomaterials due to their excellent biocompatibility and low Young's modulus. The TTNZ samples herein were manufactured by selective laser melting and the novel material was evaluated as a dental implant in vitro and in vivo. The microstructure, mechanical properties, electrochemical behaviour, cytotoxicity, haemocompatibility and osteogenic differentiation were systematically investigated. Based on the tensile test results, the as-printed TTNZ samples had an elongation of 20.23% ± 1.95%, an ultimate tensile strength of 646.61 ± 24.96 MPa and a Young's modulus of 23.72 ± 1.18 GPa. According to the biocompatible value, the as-printed TTNZ sample exhibited no cell cytotoxicity and it showed even better cell adhesion ability than that of the as-printed Ti-6Al-4 V and wrought Ti-6Al-4 V samples. The haemolysis percentage of the as-printed TTNZ sample was 0.629% ± 0.363%. Moreover, the as-printed TTNZ sample facilitated protein adsorption and osteogenic differentiation of human osteoblast-like (MG-63) cells in vitro. The in vivo data also demonstrated the histocompatibility of the as-printed TTNZ. In summary, the as-printed TTNZ developed in this study demonstrated good biocompatibility, low stress shielding, excellent ductility and great osteogenic differentiation. These results indicated that as-printed TTNZ alloys can be promising for end-use human biomedical applications.

Intraperitoneal injections of copper ferrite nanoparticles disturb blood, plasma, and antioxidant parameters of Wistar rats in a sex-specific manner

The present study was designed to report the synthesis and characterization of copper ferrite nanoparticles (CF NPs) and their biocompatibility in Wistar rats. Coprecipitation method was used to generate CF NPs having average diameter of 14.06 nm. NPs were characterized by scanning electron microscopy and X-ray diffraction. Six-week-old Wistar rats of both sexes intraperitoneally received 10 mg/ml saline/Kg body weight of CF NPs for 14 days. Control groups were maintained in parallel that received saline solution for 14 days through same route. Open field and novel object recognition tests, complete blood count, selected plasma parameters, antioxidants, and copper concentration in vital organs were determined in all treatments. Female rats treated with CF NPs had significantly higher platelet count (P = 0.05) and platelet crit (P = 0.05) and decreased plasma triglyceride concentration levels (P = 0.02) than control group. Female rats had significantly increased levels of superoxide dismutase (P = 0.01), catalase (P = 0.05), and malonaldehyde (P = 0.05) in the kidney, while male rats had significantly elevated levels of superoxide dismutase in the lungs (P = 0.01) as compared with respective control groups. Copper concentrations in the liver were significantly higher in both female (P = 0.04) and male (P = 0.05) rats exposed to CF NPs than control group. All other studied parameters of behavioral tests, blood biochemistry, antioxidant, and copper concentrations in the brain varied nonsignificantly (P > 0.05) when compared between CF NPs treated and untreated rats of both sexes. Intraperitoneal supplementation of CF NPs for 14 days disturbed the platelet count, plasma triglyceride concentration, copper levels in the liver, and antioxidant concentrations in the kidney of female Wistar rats. These parameters remained unaffected in male subjects.

Materials for Orthopedic Bioimplants: Modulating Degradation and Surface Modification Using Integrated Nanomaterials

Significant research and development in the field of biomedical implants has evoked the scope to treat a broad range of orthopedic ailments that include fracture fixation, total bone replacement, joint arthrodesis, dental screws, and others. Importantly, the success of a bioimplant depends not only upon its bulk properties, but also on its surface properties that influence its interaction with the host tissue. Various approaches of surface modification such as coating of nanomaterial have been employed to enhance antibacterial activities of a bioimplant. The modified surface facilitates directed modulation of the host cellular behavior and grafting of cell-binding peptides, extracellular matrix (ECM) proteins, and growth factors to further improve host acceptance of a bioimplant. These strategies showed promising results in orthopedics, e.g., improved bone repair and regeneration. However, the choice of materials, especially considering their degradation behavior and surface properties, plays a key role in long-term reliability and performance of bioimplants. Metallic biomaterials have evolved largely in terms of their bulk and surface properties including nano-structuring with nanomaterials to meet the requirements of new generation orthopedic bioimplants. In this review, we have discussed metals and metal alloys commonly used for manufacturing different orthopedic bioimplants and the biotic as well as abiotic factors affecting the failure and degradation of those bioimplants. The review also highlights the currently available nanomaterial-based surface modification technologies to augment the function and performance of these metallic bioimplants in a clinical setting.

Synthesis, characterization, and biocompatibility of lanthanum titanate nanoparticles in albino mice in a sex-specific manner

The aim of this study is to report the synthesis, characterization, and biocompatibility of lanthanum titanate nanoparticles (LT NPs) in albino mice. Microemulsion method was used to generate LT NPs. Seven-week-old albino mice of both sexes orally received 50 mg/ml saline/kg body weight of nanoparticles for 15 days (group 1) and 29 days (group 2). Control groups were maintained in parallel. Selected behavioral (rotarod, light and dark box, open-field and Morris water maze) tests were conducted, blood biochemical analysis was done, and antioxidants were determined in vital organs of all treatments. Male mice treated with LT NPs for 15 days spent significantly more time in light and less time in dark during light dark box test. While they had made significantly more platform entries and platform maximum visits during acquisition phase of Morris water maze test, they remained unaffected in probe trail performance when compared with control. These male mice had significantly reduced white blood cells, lymphocyte, and monocyte count and significantly increased triglyceride levels in serum than the control group. They had higher level of superoxide dismutase (SOD) in heart and reduced level of malonaldehyde (MDA) in kidney while 15-day LT NP-treated females had significantly higher level of SOD in liver and kidney. Male mice treated with NPs for 29 days had increased anticlockwise rotations during open field, reduced level of triglycerides in serum, and significantly higher level of SOD in kidney and MDA in lungs. In contrast, female mice treated with NPs for 29 days had higher SOD level in liver, kidney, and heart than their control group. Oral supplementation of LT NPs for variable duration improved the exploratory behavior in male but disturbed blood chemistry and antioxidants from vital organs under both experimental conditions.

Short-term exposure to titanium, aluminum and niobium (Ti-6Al-4Nb) alloy powder can disturb the serum low-density lipoprotein concentrations and antioxidant profile in vital organs but not the behavior of male albino mice

A group of seven-week-old albino mice of both genders were orally administered with a suspension of 25 mg Ti-6Al-4Nb/ml of saline/kg body weight and evaluated in comparison with a control group of animals treated with saline. Evaluation of both the groups was conducted through behavioral tests (Rota rod, open field, novel object and light dark box test), blood biochemical tests [complete blood count and selected serum parameters ([cholesterol, high-density lipoproteins, low-density lipoproteins, creatinine and triglycerides)] and on the basis of measured concentration of antioxidant metabolites (superoxide dismutase, catalase and lipid peroxidation) in vital organs (brain, heart, liver, kidney and lungs). Based upon the results of these tests, it has been found that the applied dose of Ti-6Al-4Nb alloy powder has not effect on physical and neurological outcome of these animals. However, it can increase low-density lipoprotein concentrations as well as disturb the H₂O₂ and lipid peroxidation associated metabolic pathways, especially in male albino mice. Whereas all other hematological indices and antioxidative stress parameters were unaffected.