Body Fluid Environment Research Articles

Corrosion resistance and biodegradability of micro-arc oxidation coatings with the variable sodium fluoride concentration on ZM21 magnesium alloys

As a biodegradable metal implant material with mechanical properties closest to those of natural bone, the degradation rate of magnesium (Mg) alloy is so fast in body fluid environment. Therefore, the preparation of a coating on Mg alloy surface to improve its corrosion resistance has become a research focus. In the study, Mg-2Zn-Mn (ZM21) alloys and micro-arc oxidation (MAO) are used as the substrate and surface modification method, respectively. Then, the influence of sodium fluoride (NaF) concentration in silicate basic electrolyte on the corrosion resistance and biodegradability of MAO coatings are investigated. The results show that (1) When NaF concentration increases to 1.0 g/L, the thickening and hydrophilic effect of MAO coating are more obvious. (2) Adding 1.0 g/L NaF makes excellent corrosion resistance and great adhesion, because F- can enhance discharge and refine sparks to enhance the interface adhesion and form a more uniform surface. (3) Excessive NaF concentration (＞ 1.0 g/L) can decrease the breakdown voltage, produce the abundant discharge channels, and degrade the coating quality. (4) The remarkable reduced weight loss rate and pH value of MAO samples after immersion shows the certain biological safety. (5) Cytotoxicity and cell adhesion test proves the available biocompatibility.

Filtered cathodic vacuum arc deposition of tetrahedral amorphous carbon thin films on surgical blades and its corrosion resistance in phosphate buffer solution (PBS) at pH 7.4

Surgical blades are prone to corrosion in a body fluid environment, increasing the risk of surgical infection and inflammation. In this paper, the ta-C thin films was deposited on surgical blades by filtered cathode vacuum arc (FCVA) method. Modern analytical methods such as SEM, Raman, surface profiler and electrochemical corrosion were used for the test and analysis. The results show that the corrosion potential and corrosion current density of uncoated surgical blades are −507 mV and 2.43 μA/cm2 during surgery operation in a simulated human environment (pH 7.4 PBS solution), and the corrosion potential of the ta-C thin films surgical blades immersed in 0.25 h, 0.5 h and 1 h are −395 mV, −431 mV, −445 mV, and the corrosion current density are 1.11 μA/cm2, 1.46 μA/cm2, 1.58 μA/ cm2. The results show that the ta-C thin films surgical blades are excellent corrosion resistance during surgery operation in a simulated human environment. SEM shows that the ta-C thin films surgical blades have a smooth surface with a compact and uniform films structure, and the thicknesses of the ta-C thin films and Ti transition layer are 2.2 µm and 2.4 µm respectively. The surface profiler shows that the average roughness of the surgical blades and the ta-C thin films surgical blades are 295.979 nm and 477.417 nm. Raman shows that ta-C thin films is of high purity, without any impurity phase, and does not cause other adverse reactions during surgery operation.

Plasma Sputtering of Nano-CaTiO3 Thin Film Applied for Surface Modification of Co–Cr Alloy

A biocompatible and corrosion-resistant coating was progressed by depositing a thin film of calcium titanate (CaTi[Formula: see text] on CoCr-based alloy substrate using a radiofrequency magnetron plasma sputtering process to improve the characteristics of the interface between the thin-film coating and the CoCr alloy substrate. In this technique, the best power was previously observed at 225 W to get good coating film deposition properties. This power was applied to a deposited thin film of CaTiO3 on a heated CoCr-based alloy at [Formula: see text]C using an argon gas atmosphere with purity (99.8%) under vacuum 1.00E-02 Torr. Different deposition rates and times were used to observe nanofilm, the thicknesses of (50 nm, 80 nm, 110 nm and 140 nm). Field-emission scanning electron microscopy (FESEM) was applied to study surface morphologies. X-ray diffraction (XRD) was used to study the crystalline structure of thin films deposited. The Vickers Micro-Hardness tests were implemented on each specimen. Vitro electrochemical corrosion tests (open circuit potential, Tafel polarization curve and cyclic polarization) of the coated and uncoated specimens were done, to find the optimal state that gives excellent resistance to corrosion in a simulated body fluid environment. The results of the experiments showed that as the thickness of the thin films increased, so did the hardness measurements. An enhancement in corrosion resistance also was clearly observed at a thickness of 140 nm CaTiO3 thin-film compared with uncoated and coated specimens at other nanothicknesses.

Surface modification of titanium implant for repairing/improving microenvironment of bone injury and promoting osseointegration

• A coating consist of MnO 2 nanoenzyme and Sr ions was fabricated on Ti implant. • MnO 2 nanoenzyme alleviated OA and O 2 deficiency at the injury site. • Sr ions released from the surface of implant promoted the growth of MSCs. • The modified Ti implant significantly accelerate bone regeneration in vivo . Bone injury and implantation operation are often accompanied by microenvironment damage of bone tissue, which seriously affects the process of osseointegration of implants, especially for titanium (Ti)-based bioinert materials. Thus, repairing or improving the microenvironment of damaged bone tissue is of great significance for bone rescue, reconstruction, and regeneration still a major medical challenge. Oxidative stress (OS) and oxygen (O 2 ) deficiency are considered to be specific physiological signals of the bone-injury microenvironment. From the above background, a coating consisting of manganese dioxide (MnO 2 ) nanoenzyme and strontium (Sr) ions was fabricated on the surface of the Ti implant via a one-step hydrothermal treatment. MnO 2 nanoenzyme presented in the coating alleviated OS and O 2 deficiency at the injury site by catalyzing the decomposition of abundant endogenous H 2 O 2 around the modified Ti implants into O 2 . In addition, Sr ions were released from the surface of the implant at a certain rate in a body-fluid environment, further promoting the adhesion, growth, and osteogenic differentiation of mesenchymal stem cells. More importantly, a Sprague Dawley rat femur model demonstrated that the modified Ti implant showed significant potential to accelerate bone tissue reconstruction in vivo . In summary, the present system provides a new idea for the treatment of bone injury and the development of new orthopedic implants.

Influence of Hafnium Addition on the Microstructure, Microhardness and Corrosion Resistance of Ti20Ta20Nb20(ZrMo)20-xHfx (where x = 0, 5, 10, 15 and 20 at.%) High Entropy Alloys.

The presented work aimed to investigate the influence of the hafnium/(zirconium and molybdenum) ratio on the microstructure, microhardness and corrosion resistance of Ti20Ta20Nb20(ZrMo)20-xHfx (where x = 0, 5, 10, 15 and 20 at.%) high entropy alloys in an as-cast state produced from elemental powder and obtained via the vacuum arc melting technique. All studied alloys contained only biocompatible elements and were chosen based on the thermodynamical calculations of phase formation predictions after solidification. Thermodynamical calculations predicted the presence of multi-phase, body-centered cubic phases, which were confirmed using X-ray diffraction and scanning electron microscopy. Segregation of alloying elements was recorded using elemental distribution maps. A decrease in microhardness with an increase in hafnium content in the studied alloys was revealed (512-482 HV1). The electrochemical measurements showed that the studied alloys exhibited a high corrosion resistance in a simulated body fluid environment (breakdown potential 4.60-5.50 V vs. SCE).

Record Ultralarge-Pores, Low Density Three-Dimensional Covalent Organic Framework for Controlled Drug Delivery.

The unique structural characteristics of three-dimensional (3D) covalent organic frameworks (COFs) like high surface areas, interconnected pore system and readily accessible active sites render them promising platforms for a wide set of functional applications. Albeit promising, the reticular construction of 3D COFs with large pores is a very demanding task owing to the formation of interpenetrated frameworks. Herein we report the designed synthesis of a 3D non-interpenetrated stp net COF, namely TUS-64, with the largest pore size of all 3D COFs (47 Å) and record-low density (0.106 g cm-3 ) by reticulating a 6-connected triptycene-based linker with a 4-connected porphyrin-based linker. Characterized with a highly interconnected mesoporous scaffold and good stability, TUS-64 shows efficient drug loading and controlled release for five different drugs in simulated body fluid environment, demonstrating the competency of TUS-64 as drug nanocarriers.

Record Ultralarge‐Pores, Low Density Three‐Dimensional Covalent Organic Framework for Controlled Drug Delivery**

AbstractThe unique structural characteristics of three‐dimensional (3D) covalent organic frameworks (COFs) like high surface areas, interconnected pore system and readily accessible active sites render them promising platforms for a wide set of functional applications. Albeit promising, the reticular construction of 3D COFs with large pores is a very demanding task owing to the formation of interpenetrated frameworks. Herein we report the designed synthesis of a 3D non‐interpenetrated stp net COF, namely TUS‐64, with the largest pore size of all 3D COFs (47 Å) and record‐low density (0.106 g cm−3) by reticulating a 6‐connected triptycene‐based linker with a 4‐connected porphyrin‐based linker. Characterized with a highly interconnected mesoporous scaffold and good stability, TUS‐64 shows efficient drug loading and controlled release for five different drugs in simulated body fluid environment, demonstrating the competency of TUS‐64 as drug nanocarriers.

Cytotoxic and osteogenic property of trilaurin assisted hydroxyapatite nanorods in simulated body fluid environment

In this research work, the cytogenic and osteogenic properties of biomimetically synthesised nanohydroxyapatite (nanoHAP) powders using Trilaurin (TL), as a surfactant was attempted. Microwave (MW) and ultrasound (US) technologies were also employed to enhance the efficacy of the method. Different HAP samples were prepared using 1.5 times concentrated Simulated Body Fluid (SBF) with 1, 5 and 15 days immersion inorder to achieve pure nanohydroxyapatite powders. The formation of HAP was well supported by FTIR and Raman spectroscopy, which shows no impurity peaks. By increasing the time of soaking in SBF, growth, size and crystallinity of HAP were found to decrease as evidenced by XRD data. HRSEM studies reveal that nano-plates and rod shaped nano HAP could be obtained by this method. So the obtained TL assisted HAP exhibits high thermal stability as confirmed by TGA analysis. The invitro cytotoxicity was evaluated by 3-(4, 5-dimethyl-2-thiazolyl)-2, 5-diphenyl-tetrazolium bromide (MTT) assay using human osteoblastic cell line (MG-63) and Michigan Cancer Foundation-7 (MCF-7) breast cancer cell line. The obtained result supports the osteoblast property and less toxicity. Inorder to further prove the osteoblast property, trypan blue exclusion test (live dead assay) were carried out using MG-63 cell line and the obtained results favours the bone forming ability.

Comparative Study on Wear Behaviors of Monolayer and Heterogeneous Multilayer Ta Coatings in Atmospheric and SBF Environments

Monolayer Ta and multilayer Ti/Zr/Ta and Zr/Ti/Ta coatings were prepared by magnetron sputtering on TC4 substrates to improve the surface friction and wear properties in a simulated body fluid (SBF) environment and an atmospheric environment. Optical microscopy, scanning electron microscopy, laser scanning confocal microscopy and nano scratch testing were employed to establish the structure-property-environment relationships. By controlling the preparation parameters, the outermost layer of all three samples was Ta coating, and the total coating thickness of each sample was about 3 μm. Friction and wear testing revealed that, compared to bare TC4 substrate, and multilayer Ti/Zr/Ta and Zr/Ti/Ta coatings, the monolayer Ta possessed the lowest friction coefficient as well as the minimum wear rate (i.e., calculation result of the wear track width and wear depth). This was mainly attributed to excellent adhesion strength, a particular structure and solid lubrication of the monolayer coating. The same coating sample exhibited a stronger wear resistance in the SBF environment than in the atmospheric environment. Furthermore, the wear behaviors and mechanisms of various coatings under different experimental environments are also discussed.

A CD326 monoclonal antibody modified core cross-linked curcumin-polyphosphoester prodrug for targeted delivery and cancer treatment.

Stimuli-responsive cross-linked micelles (SCMs) are ideal nanocarriers for anti-cancer drugs. Compared with non-cross-linked micelles, SCMs exhibit superior structural stability. At the same time, the introduction of an environmentally sensitive crosslinker into a drug delivery system allows SCMs to respond to single or multiple stimuli in the tumor microenvironment, which can minimize drug leakage during the blood circulation process. In this study, curcumin (CUR) was modified as the hydrophobic core crosslinker by utilizing the bisphenol structure, and redox sensitive disulfide bonds were introduced to prepare the glutathione (GSH) stimulated responsive core crosslinker (abbreviated as N3-ss-CUR-ss-N3). In addition, amphiphilic polymer APEG-b-PBYP was prepared through the ring opening reaction, and reacted with the crosslinker through the "click" reaction. After being dispersed in the aqueous phase, core cross-linked nanoparticles (CCL NPs) were obtained. Finally, monoclonal antibody CD326 (mAb-CD326) was reduced and coupled to the hydrophilic chain ends to obtain the nanoparticles with surface modified antibodies (R-mAb-CD326@CCL NPs) for further enhancing targeted drug delivery. The structures of the polymer and crosslinker were characterized by 1H NMR, UV-Vis, FT-IR, and GPC. The morphology, size and stability of CCL NPs and R-mAb-CD326@CCL NPs were investigated by DLS and TEM. The in vitro drug release behavior of CCL NPs was also studied. The results showed that the CCL NPs exhibited reduction-responsiveness and were able to release the original drug CUR under 10 mM GSH conditions. Additionally, the CCL NPs exhibited excellent stability in both the simulated body fluid environment and organic solvents. Especially, R-mAb-CD326@CCL NPs can actively target tumor cells and showed better therapeutic efficacy in in vivo experiments with a tumor suppression rate of 78.7%. This work provides a new idea for the design of nano-drugs targeting breast cancer.

Friction and Wear Properties of Multilayer Films Designed on Tantalum Substrate

In this paper, a titanium nitride film (TiN) monolayer film was deposited on a pure Tantalum (Ta) substrate with Ti as an intermediate layer by magnetron sputtering technique, and a Ta/Ti/DLC (diamond-like carbon)/Ti/TiN/DLC multilayer film was designed. Raman spectroscopy and scanning electron microscopy were used to observe the film structure and morphology. Friction and wear properties of Ta/Ti/TiN monolayer film and Ta/Ti/DLC/Ti/TiN/DLC multilayer film were analyzed by UMT-3 tester. The results show that the surface of multilayer film is denser and better bonded than TiN monolayer film. Under dry friction conditions, the friction coefficient of TiN monolayer film is stable at about 0.45. In contrast, the friction coefficient of DLC multilayer film remains around 0.15 with very small fluctuation during the whole friction process. This is determined by the inherent characteristics of DLC film, which is composed of sp2-C graphite structure and sp3-C diamond structure. From the analysis of the wear mechanism, the Ta substrate mainly undergoes adhesive wear and abrasive wear, however, the TiN monolayer film and Ta/Ti/DLC/Ti/TiN/DLC multilayer films mainly undergo abrasive wear mechanism. The friction coefficient of TiN monolayer fluctuates more than that of dry friction conditions in the body-liquid environment, and finally stabilize at about 0.5. The friction coefficient of DLC multilayer films does not differ much from those of dry friction conditions. This is because the TiN monolayer film generates a large amount of abrasive chips to fill the scratches in the body fluid environment, accompanied by the peeling and flaking of the compacted abrasive chips, thus the friction coefficient fluctuates greatly. The DLC multilayer films also undergoes graphitization transfer. In addition, the free hanging bonds of DLC film are passivated, which reduces the degree of adhesive wear. In summary, the DLC multilayer film has better biocompatibility, wear resistance, and stronger bonding.

Reduction of the in vitro toxicity of elevated concentrations of SPIONLA by its administration through PHBV/curcumin composite microspheres

Superparamagnetic iron oxide nanoparticles have been developed for various biomedical applications for decades. In this work, lauric acid-coated SPION (SPIONLA) were incorporated into poly (3-hydroxybutyrate-co-3-hydroxyvalerate) (PHBV) at different ratios to produce composite microspheres, which were evaluated for their properties, including potential cytotoxicity. Additionally, a phytotherapeutic extract, curcumin, was loaded into the resulting microspheres to develop magnetic drug delivery capsules. The results show a significant improvement in the cytocompatibility after 7 days of SPIONLA administrated in cells through the composite microspheres compared to pristine SPIONLA. The composite also exhibited prolonged cumulative release of curcumin in a simulated body fluid environment. The results confirmed the efficacy of the mixture of PHBV and curcumin in attenuating potential side effects due to direct administration of high initial amounts of SPIONLA while maintaining magnetic properties in the resulting composite. The results add evidence to the potential of these composite devices for targeted drug delivery applications.

Corrosion of NiTi stents induced by galvanic interaction with radiopaque materials

Nickel titanium (NiTi) alloys are used as a base material for biomedical devices and implants, such as stents. One limitation associated with NiTi stents is the low radiopacity. Thus, radiopaque markers, made of noble materials, are usually attached to NiTi stents to increase the stent radiopacity, raising concerns regarding galvanic corrosion in body fluid environments. This research aims to assess the galvanic interactions of NiTi alloys and NiTi stent when coupled to radiopaque markers materials in simulated body fluid solution (NaCl 0.9%). Electrochemical measurements, using flat specimens and NiTi stents were carried out. After the tests, scanning electron microscopy (SEM) surface analysis was performed. The results from polarization curves indicate that the NiTi/Platinum (NiTi/Pt) couple is more susceptible to galvanic corrosion than the pairs of NiTi/Palladium (NiTi/Pd) and NiTi/Gold (NiTi/Au). The potential difference of 628 mV presented by the NiTi/Pt couple was the highest among the galvanic couples investigated. Higher values of galvanic potential and galvanic current were also obtained by the pair NiTi/Pt. In direct galvanic short-term measurements with NiTi stent/Pt, no increase in the current density or presence of pits on the NiTi stent surface was observed. However, long-term potentiostatic test, applying 280 mV, which corresponds to the galvanic potential of the NiTi/Pt couple, resulted in current peaks of 1.500 µA and led to severe localized corrosion of NiTi stents, revealing a risk of corrosion induced by coupling Pt markers to NiTi stent.

Development of Hydroxyapatite Coating on Titanium Alloy for Orthopedic Applications

Titanium and its alloys have long been employed in biomedical applications due to its remarkable features, such as good bio-compatibility, resistance to bodily fluid effects, tremendous tensile strength, flexibility, and high corrosion resistance. If these materials are used as bio-implant, it releases toxic ions like aluminium and vanadium in the body fluid environment after implantation to overcome the problem Ti-6Al-4V alloy was coated with hydroxyapatite (HAp) which provides better bioactivity, osteocompatibility, and antibacterial activity. The present work is to synthesize HAp from snail shells using a simple wet precipitation method. The prepared SHAp was coated on the Ti-6Al-4V alloy using electro-deposition method. The coated alloy was characterized by various techniques such as FTIR, XRD, FESEM, EDAX, AFM and antibacterial activity. The spherical like structures was observed on the coated metal surface using FESEM. The potentiodynamic polarization study indicate that the breakdown potential (Eb) and repassivation potential (Ep) of uncoated sample was found to be 175.5 mV and −105.1 mV and for the coated sample was noticed at 357.2 mV and −50.2 mV respectively. The potential shift was moving towards the noble direction and it controls the rate of corrosion on coated Ti-6Al-4V. The zone of inhibition values were found to be 11.0 ± 0.45 mm for gram negative bacteria and 8.2 ± 0.28 mm for gram positive bacteria which was confirmed by the antibacterial activity study. The anti-bacterial activity of SHAp coated Ti-6Al-4V was superior to E. coli than Staphylococcus aureus. It is concluded that SHAp coated Ti-6Al-4V alloy may be considered a better material for orthopedic applications.

Unraveling the role of micro-arc oxidation process factors on the corrosion resistance of magnesium alloy microtubes

This study employed Micro Arc Oxidation (MAO) to coat ceramic-based coating on fabricated microtubes for biological applications. Although there is information on the MAO coating of sheets and plates, there is relatively little technical information on applying the MAO method to tubes. The impact of crucial MAO process parameters such as current density, inter-work distance, and coating time on the microstructure, porosity, and corrosion resistance of MAO coating deposit on friction stir back extrusion magnesium alloy microtube was studied. The central composite rotatable design was used to conduct experimental runs involving three parameters, modified at three distinct levels. According to the design matrix, cross-sectional images of MAO-coated magnesium microtube were used to quantify interface microstructure . The porosity and corrosion resistance of coated microtubes were tested in a simulated body fluid environment, and the results were connected with process variables using an empirical connection. The usage of MAO coating has been found to have promising outcomes in extending life, lowering corrosion degradation rates, and improving mechanical integrity.

Fretting wear properties and microstructure evolution in micro-arc oxidation bioceramic coating pretreated using laser remelting

To improve fretting wear resistance, bio-ceramic coatings were successfully fabricated on TC6 alloy substrates using a combination of laser remelting (LRM) and micro-arc oxidation (MAO). The surface morphology, composition, and residual stress distribution of the coatings were characterized using scanning electron microscopy, energy-dispersive spectroscopy, X-ray diffraction, ultra-deep field three-dimensional microscopy, and X-ray stress analysis. The influence of LRM pretreatment on the fretting wear behaviour of MAO bioceramic coatings was investigated. The LRM pre-treatment did not change the phase composition of the MAO coatings, which were all composed of Al2TiO5, rutile TiO2, and anatase TiO2 phases. However, increasing the content of the rutile TiO2 phase from 68 to 89% improved the uniformity and density of the coatings and decreased the porosity by 2.8%. The fretting wear test results showed that the LRM pretreated MAO coating exhibited the best performance against fretting wear in a simulated body fluid environment. In this case, the fretting wear mechanism was attributed to slight delamination and fatigue wear.

Effects of Different Concentrations of BSA on In Vitro Corrosion Behavior of Pure Zinc in Artificial Plasma

When medical metallic materials are implanted in the body and come into contact with the body fluid environment, proteins will be rapidly adsorbed on the surface and affect the corrosion process of the material. Currently, there is no uniform understanding of the effect of protein adsorption on the corrosion behavior of materials due to the limitations of the nature of metal materials, protein concentrations, and different media environments. The effect of various bovine serum albumin (BSA) concentrations in artificial plasma (AP) on the corrosion behavior of pure Zn during 14 days of immersion was investigated in this research. The corrosion rate of pure Zn was slowed down by the addition of BSA, and the decelerating effect of lower protein concentration on the corrosion rate of Zn was more significant in the initial stage of immersion. With prolonging the immersion time, the corrosion rate of pure Zn in different media slowed down and stabilized, and the corrosion rates of pure Zn showed a decreasing trend with an increase of BSA concentration. Furthermore, the Langmuir adsorption isotherm model was utilized to study the relationship between the BSA concentration and corrosion behavior of pure Zn and to analyze the role of proteins in the degradation mechanism of pure Zn. This work could be useful for further exploration of potential clinical applications of zinc alloys.

Insights of Microstructural Features and Their Effect on Degradation and the In Vitro Bioactivity Response of as-Cast Mg-Sn Alloys for Orthopedic Implant Applications.

The present work focuses on a deep understanding of microstructural evolution and phase formation in a binary Mg-Sn alloy system. Mg-xSn (x = 1, 5, 10 wt.%) alloys were cast using a squeeze casting technique. Phase identification and microstructural analysis were done using XRD (X-ray Diffraction) and FESEM with EDS (Field Emission Scanning Electron Microscopy with Energy Dispersive X-ray Spectroscopy), respectively. The mechanical behavior of the alloys under study was evaluated by conducting a compression test. The corrosion behavior of all the alloys were intricately studied using electrochemical corrosion tests and an immersion test in the simulated body fluid (SBF) environment for different immersion periods. The bioactivity response of Mg-Sn alloys systems under this study was investigated by immersing the samples in SBF for 14 days. From the analysis of the results, it was understood that the amount of Sn addition has a large influence on the metallurgical, corrosion, and bioactivity properties. Interesting facts about the intermetallic phase formation and segregation of Sn were observed when the wt.% of Sn was varied in the alloy and the evolution of the microstructure was described clearly. Mechanical properties of Mg-Sn alloys were improved, as the Sn content increased up to 5 wt.% and declined in the case of a 10 wt.% Sn addition. A similar trend was observed even in the case of corrosion resistance and bioactivity properties. Among the alloy compositions studied, Mg with a 5 wt.% addition has proved to be a promising candidate material for orthopedic implant applications with an acceptable elastic modulus, higher corrosion resistance, and an excellent bioactive response.

Compositional design and in vitro investigation on novel Zr–Co–Cu–Ti metallic glass for biomedical applications

Zr–Co–Cu–Al based metallic glasses (MGs) are potential material for making surgical equipment due to their ultra-high strength. However, presence of elemental Al in these alloys is not desirable due to biotoxicity. To counter this problem the present study is undertaken to design metallic glass forming composition by replacing Al with Ti. Design strategy adopted is based on thermodynamic modelling by rationalizing the effect of chemical enthalpy and atomic mismatch entropy along with statistically controlled atomic arrangement through configurational entropy. The rapid solidification technique was used to synthesize MG in melt spun ribbon form. The structural nature and glass stability of the ribbon are confirmed by X-Ray diffraction, transmission electron microscopy and differential scanning calorimetry. Corrosion response of the MG is thoroughly investigated using potentiodynamic polarization and electrochemical impedance spectroscopy in a simulated body fluid (SBF) environment. The mechanical property of MG is evaluated using microindentation technique. Improvement in corrosion resistance is observed in all the SBF solutions along with in vitro biocompatibility study using MG-63 cell viability experiment.

Effect of Al content on the selective leaching property of AlxCoCrFeNi high-entropy alloys

This study investigates the selective leaching behavior of Al0.2CoCrFeNi, Al0.6CoCrFeNi, and Al1CoCrFeNi high-entropy alloys (HEAs) in a simulated body fluid environment to assess their potential long-term orthopedic implant applications. The concentrations of Al, Cr, and Fe ions released from the AlxCoCrFeNi HEA were relatively lower than those of the Co and Ni ions because Al, Cr, and Fe atoms are primarily in their oxidation states near the surface of the alloys. The selective leaching property of the Al0.2CoCrFeNi HEA was slightly worse than that of the CoCrFeNi medium-entropy alloy because the porous and poorly protective Al2O3 films formed on the surface of the Al0.2CoCrFeNi HEA deplete the protection of the Cr2O3 and Fe2O3 passive films. Furthermore, the concentrations of the metal ions released from the Al0.6CoCrFeNi and Al1CoCrFeNi HEAs were much higher than those released from the Al0.2CoCrFeNi HEA because their complicated BCC + FCC dual-phase structure facilitates the selective leaching rates of the ions. AlxCoCrFeNi HEAs with a fully single-phase structure were found to be suitable for biomaterials, whereas those with a dual-phase structure exhibited poor selective leaching properties and were found to be inadequate for long-term implant applications.