Simulated Body Fluid Conditions Research Articles

Ti3C2Tx MXene-functionalized Hydroxyapatite/Halloysite nanotube filled poly– (lactic acid) coatings on magnesium: In vitro and antibacterial applications

Magnesium (Mg) stands out in temporary biomaterial applications due to its biocompatibility, biodegradability, and low Young's modulus. However, controlling its corrosion through next-generation polymer-based functional coatings is crucial due to the rapid degradation behavior of Mg. In this study, the function of 2D lamellar Ti3C2Tx (MXene) in Hydroxyapatite (HA) and Halloysite nanotube (HNT) hybrid coatings in biodegradable poly– (lactic acid) (PLA) was investigated. The morphological and structural characterizations of the coatings on Mg were revealed through HRTEM, XPS, SEM-EDX, XRD, FTIR, and contact angle analyses/tests. Electrochemical in vitro corrosion tests (OCP, PDS, and EIS-Nyquist) were conducted for evaluate corrosion resistance under simulated body fluid (SBF) conditions. The bioactivity of the coatings in SBF have been revealed in accordance with the ISO 23,317 standard. Finally, antibacterial disk diffusion tests were conducted to investigate the functional effect of MXene in coatings. It has been determined that the presence of MXene in the coating increased not only surface wettability (131°, 85°, 77°, and 74° for uncoated, pH, PHH, and PHH/MXene coatings, respectively) but also increased corrosion resistance (1857.850, 42.357, 1.593, and 0.085 × 10–6, A/cm2 for uncoated, pH, PHH, and PHH/MXene coatings, respectively). It has been proven that the in vitro bioactivity of PLA-HA coatings is further enhanced by adding HNT and MXene, along with SEM morphologies after SBF. Finally, 2D lamellar MXene-filled coating exhibits antibacterial behavior against both E. coli and S. aureus bacteria.

Synergistic impact of scan strategy and scan angles in laser powder bed fusion process on mechanical, tribological and cell viability properties of porous 316L SS structure

Poor load bearing ability and concentrated stress within cross-linked porous structures was found to be the major cause for the mechanical and wear failure of SS (Stainless Steel) 316L implants. Therefore, the present study introduces a novel scan pattern to enhance the mechanical and wear properties. Importantly, the role of porous structures on the constituents and formation of Tribo-film regimes under the simulated body fluid (SBF) condition were assessed using the X-ray photoelectron spectroscopy (XPS). Furthermore, the impact of the surface roughness of porous structures on the cell adhesion and cytotoxicity were explored. Various cross-linked porous structures are produced at three different scanning rotation angles (0°, 45°, and 90°) using the Laser powder bed fusion (LPBF) process. Morphology analysis reveals balling and stair-case effects at 0°, controlled for structures built at 45° and 90°. Porous-90° structure exhibits negative skewness and a platykurtic surface with low peaks and more valleys. It demonstrates higher strength with low density due to better particle fusion, net-like structure, and uniform element distribution. X-ray photoelectron spectroscopy (XPS) evaluates the impact of porous structures on Tribo-film regimes in simulated body fluid. Surface roughness effects on cell adhesion and cytotoxicity are also investigated. Cross linked porous structures presented two major compression failure modes include wrinkling and diagonal shearing. The densified structure of Porous-45° reduces contamination and cell death, facilitating stable cell growth. Tribo-film formation and load bearing ability of Porous-90° structure was better than the other structures, due to the cross-linked netlike structure and further more detailed in the XPS study.

Tribological behavior and biocompatibility of novel Nickel-Free stainless steel manufactured via laser powder bed fusion for biomedical applications

Due to the risk of releasing carcinogenic nickel ions from conventional 316L stainless steel under a corrosive human body environment, a new variant of steel termed nickel-free stainless steel (NiFSS) has been investigated. The present study investigates the tribological properties and biocompatibility of NiFSS manufactured via laser powder bed fusion (PBF-LB/M). The ferritic NiFSS exhibited significantly lower coefficient of friction (0.08 to 0.28) and wear rate (1.60 × 10-6 mm3/Nm to 6.60 × 10-6 mm3/Nm) compared to reported values for austenitic 316L SS, under both dry and simulated body fluid (SBF) conditions and various sliding geometries. This improvement is attributed to the superior hardness (3.394 ± 0.1340 GPa) and elastic modulus (238 ± 9.0797 GPa) of NiFSS. To assess the biocompatibility, the viability of mouse pre-osteoblastic MC3T3-E1 cells was evaluated with an Alamar Blue assay when the cells were cultured on top of PBF-LB/M built NiFSS and 316L SS samples. The results indicated that even though cell growth was most optimal on regular cell culture plastic, cell viability was better maintained on PBF-LB/M built NiFSS compared to 316L SS. Therefore, the results of the present study propose that PBF-LB/M fabricated NiFSS holds promise for application in biomedical devices for joint arthroplasty.

Tensile strength and immersion corrosion behavior of nano-ZnO, rare earth Gd reinforced Mg nanocomposites developed by novel stir ultrasonication process

This paper presents the tensile and immersion corrosion properties of Mg-Zn-0.2Gd-xZnO (x = 1, 1.5, 2 and 2.5 wt.%) alloy and nanocomposites developed by stir ultrasonication coupled with squeeze casting. The immersion corrosion tests were performed under the simulated body fluid (SBF) conditions. The microscopic measurements indicate that the examined alloys/nanocomposites exhibit a significant decrease in grain size when both alloying elements Gadolinium (Gd) and Zinc Oxide (ZnO) nanoparticles are added. The examination of the phase by XRD indicates the presence of α-Mg and Mg2Zn, Mg7Zn3 secondary phases, which act as barriers against corrosion. The study confirmed that the incorporation of nanoparticles ZnO content ranging from 1 to 2.5 wt. % leads to a notable enhancement in yield strength (140 to 230 MPa). From the immersion corrosion test, the nanocomposites with the inclusion of 2 wt. % ZnO ceramic nanoparticles resulted in the highest level of corrosion resistance with a corrosion rate of 0.049 mm per year. This nanocomposite also shows better wettability with improved hydrophilicity. The developed Mg based advanced nanocomposites have the potential to be used in load bearing implant applications as it exhibited high corrosion resistance characteristics.

Structural Parameters and Behavior in Simulated Body Fluid of High Entropy Alloy Thin Films.

The structure, composition and corrosion properties of thin films synthesized using the Pulsed Laser Deposition (PLD) technique starting from a three high entropy alloy (HEA) AlCoCrFeNix produced by vacuum arc remelting (VAR) method were investigated. The depositions were performed at room temperature on Si and mirror-like polished Ti substrates either under residual vacuum (low 10-7 mbar, films denoted HEA2, HEA6, and HEA10, which were grown from targets with Ni concentration molar ratio, x, equal to 0.4, 1.2, and 2.0, respectively) or under N2 (10-4 mbar, films denoted HEN2, HEN6, and HEN10 for the same Ni concentration molar ratios). The deposited films' structures, investigated using Grazing Incidence X-ray Diffraction, showed the presence of face-centered cubic and body-centered cubic phases, while their surface morphology, investigated using scanning electron microscopy, exhibited a smooth surface with micrometer size droplets. The mass density and thickness were obtained from simulations of acquired X-ray reflectivity curves. The films' elemental composition, estimated using the energy dispersion X-ray spectroscopy, was quite close to that of the targets used. X-ray Photoelectron Spectroscopy investigation showed that films deposited under a N2 atmosphere contained several percentages of N atoms in metallic nitride compounds. The electrochemical behavior of films under simulated body fluid (SBF) conditions was investigated by Open Circuit Potential (OCP) and Electrochemical Impedance Spectroscopy measurements. The measured OCP values increased over time, implying that a passive layer was formed on the surface of the films. It was observed that all films started to passivate in SBF solution, with the HEN6 film exhibiting the highest increase. The highest repassivation potential was exhibited by the same film, implying that it had the highest stability range of all analyzed films. Impedance measurements indicated high corrosion resistance values for HEA2, HEA6, and HEN6 samples. Much lower resistances were found for HEN10 and HEN2. Overall, HEN6 films exhibited the best corrosion behavior among the investigated films. It was noticed that for 24 h of immersion in SBF solution, this film was also a physical barrier to the corrosion process, not only a chemical one.

Low-Temperature Plasmas Improving Chemical and Cellular Properties of Poly (Ether Ether Ketone) Biomaterial for Biomineralization.

Osteoblastic and chemical responses to Poly (ether ether ketone) (PEEK) material have been improved using a variety of low-temperature plasmas (LTPs). Surface chemical properties are modified, and can be used, using low-temperature plasma (LTP) treatments which change surface functional groups. These functional groups increase biomineralization, in simulated body fluid conditions, and cellular viability. PEEK scaffolds were treated, with a variety of LTPs, incubated in simulated body fluids, and then analyzed using multiple techniques. First, scanning electron microscopy (SEM) showed morphological changes in the biomineralization for all samples. Calcein staining, Fourier transform infrared spectroscopy (FTIR), and X-ray photoelectron spectroscopy (XPS) confirmed that all low-temperature plasma-treated groups showed higher levels of biomineralization than the control group. MTT cell viability assays showed LTP-treated groups had increased cell viability in comparison to non-LTP-treated controls. PEEK treated with triethyl phosphate plasma (TEP) showed higher levels of cellular viability at 82.91% ± 5.00 (n = 6) and mineralization. These were significantly different to both the methyl methacrylate (MMA) 77.38% ± 1.27, ethylene diamine (EDA) 64.75% ± 6.43 plasma-treated PEEK groups, and the control, non-plasma-treated group 58.80 ± 2.84. FTIR showed higher levels of carbonate and phosphate formation on the TEP-treated PEEK than the other samples; however, calcein staining fluorescence of MMA and TEP-treated PEEK had the highest levels of biomineralization measured by pixel intensity quantification of 101.17 ± 4.63 and 96.35 ± 3.58, respectively, while EDA and control PEEK samples were 89.53 ± 1.74 and 90.49 ± 2.33, respectively. Comparing different LTPs, we showed that modified surface chemistry has quantitatively measurable effects that are favorable to the cellular, biomineralization, and chemical properties of PEEK.

The Biocompatibility and Self-Healing Effect of a Biopolymer’s Coating on Zn Alloy for Biomedical Applications

The objective of this study was to formulate dip coatings, incorporating casein, NaOH, and nanocrystalline hydroxyapatite (nanoHAp), with self-healing properties for application on ZnMg3.2 wt.% alloy in the field of biomedical applications. This study hypothesizes that the self-healing mechanism within the layer will impede substrate degradation by progressively filling defects where chlorides from simulated body fluids intervene. Furthermore, it aims to mitigate potential damage effects during the implantation process by the layer’s self-healing capabilities. The research focused on the dip-coating process parameters and chemical composition of baths for producing casein coatings on Zn alloy surfaces. This study investigated the impact of casein and NaOH concentration, along with the immersion time of ZnMg3.2 wt.% samples in the coating bath, on the self-healing capability of the coating under simulated human body fluid conditions (Ringer’s solution, temperature: 37 °C). Effective technology was developed by selecting specific chemical compositions and immersion times in the coating bath, enhancing the self-healing progress against coating damage in Ringer’s solution at 37 °C. The most significant self-healing effect was observed when the ZnMg3.2 wt.% substrate underwent a 1 h immersion in a coating bath containing 2 g of casein, 4 g of NaOH, and 0.1 g of nanoHAp powder. Electrochemical tests were instrumental in determining the optimal casein concentration and immersion time of the Zn alloy in the coating bath.

Poly(3-hydroxybutyrate-co-3-hydroxyvalerate) Blends with Poly(caprolactone) and Poly(lactic acid): A Comparative Study.

Poly(hydroxybutyrate-co-hidroxyvalerate) (PHBV) is a biodegradable polymer, which is a potential substitute for plastics made from fossil resources. Due to its practical interest in the field of tissue engineering, packaging, sensors, and electronic devices, the demand for PHBV with specific thermal, electrical, as well as mechanical requirements is growing. In order to improve these properties, we have developed PHBV blends with two thermoplastic biodegradable polyesters, including poly(caprolactone) (PCL) and poly(lactic acid) (PLA). We analysed the effect of these biopolymers on the morphological, wetting, structural, thermal, mechanical, and electrical characteristics of the materials. Further, the biodegradation of the samples in simulated body fluid conditions was evaluated, as well as the antibacterial activity. The results demonstrate that the blending with PCL and PLA leads to films with a dense morphology, increases the hydrophilic character, and induces a reinforcement of the mechanical characteristics with respect to pristine PHBV. In addition, a decrease in dielectric constant and a.c. electrical conductivity was noticed for PHBV/PLA and PHBV/PCL blends compared to neat PHBV polymer. All neat polymers and blends showed antibacterial properties against S. aureus, with more than 40% bacterial reduction, which increased to 72% in the presence of PCL polymer for a blend ratio of 50/50. Thus, it is demonstrated a suitable way to further tailor a variety of functionalities of PHBV for specific applications, by the development of polymer blends with PLA or PCL.

Gold Nanoparticle‐Coated Bioceramics for Plasmonically Enhanced Molecule Detection via Surface‐Enhanced Raman Scattering

Herein, feasibility of plasmonically enhanced molecule detection via surface‐enhanced Raman scattering for ceramics that are commonly used as bone or tooth replacement materials is evaluated. Open cell foams of Bioglass 45S5, the commercial hydroxyapatite‐based product Bio‐Oss, and bioinert zirconia‐toughened‐alumina (ZTA) are coated with Au nanoparticles via colloidal deposition to introduce plasmonic effects. Depending on the pore size, gold‐functionalized plasmonic porous Bioglass shows effective Raman enhancement factor (eEF) up to , while depositing gold nanoparticles on Bio‐Oss and porous ZTA resulted in eEF of and respectively. The performance of the plasmonic porous bioceramics under simulated biological conditions is examined in situ in the biological medium fetal bovine serum (FBS) and during extended incubation in mineralizing simulated body fluid (SBF). Most notably, the plasmonic porous Bioglass still delivered an eEF around after 28 days of incubation in SBF, indicating promising stability in simulated biological conditions without significant difference in SBF bioactivity before and after Au deposition. Accordingly, the plasmonically enhanced porous bioceramics offer the possibility for real‐time and sensitive molecule detection at SBF and FBS conditions and can be further developed for sensing of specific biomarkers, for example, in the context of osseointegration of bone replacement materials.

Designing organic-inorganic hybrid coating from composite and structures for the tribological property and corrosion resistance of Mg alloys

Magnesium alloys are promising materials for the regeneration of bioabsorbable implants, but restricted by its poor tribological property and the rapid corrosion. In this work, a robust organic–inorganic hybrid coating was fabricated on the surface of Mg-Nd-Zn-Zr alloys through a combination of chemical assembly technique of hydroxylated boron nitride (BNO) and plasma-enhanced chemical vapour deposition of vinyltriethoxysilane. The obtained hybrid coating simultaneously enhanced anti-wear and anti-corrosion properties in both the dry friction and simulated body fluid (SBF)-condition friction. The wear rates of the Mg alloy modified by BNO/siloxane hybrid coating were significantly reduced by 97.3% and 96.4% under dry and SBF conditions, respectively. This step-by-step coating modification method is applicable to various shapes of magnesium alloys and hence displays great potential in implant application.

Assessment on the wear failure of additively manufactured stainless steel 316L with different scan pattern in simulated body fluid condition

Because of higher contact area, the additively manufactured SS 316L (AM built 316L) generates a high frictional heat and wear in the lubricated sliding condition. So to counteract this, different scan patterns like stripe, contour and porous-chessboard were developed for AM built 316L to reduce the contact area. Importantly, the variation in scan patterns could induce different wear mechanisms when two surfaces slide against each other. Therefore, it is essential to analyse the wear failures for the different scan patterns in simulated body fluid (SBF) conditions, which was not carried out previously. In the present study, the simulated body fluid (SBF) conditions are designed to mimic the chemical and physical properties of body fluids and also, the article correlates how the tribological behaviour of AM-built 316L varies in the SBF condition. Furthermore, the porosity, elemental composition, surface roughness, density, phase structure, residual stress, hardness, friction, and wear properties of AM built 316L samples has been characterized. X-ray diffractometer (XRD) analysis confirmed the presence of high intensity γ-Fe (111) peaks for the porous-chessboard pattern, because of high dislocation density. Compressive residual stress has been reported for all scan patterns due to the difference in the thermal expansion and contraction between the built layers. Novel cross linked porous-chessboard pattern has a higher wear resistance with low COF compared to the other scan pattern. Furthermore, the exhibition of different wear mechanisms like abrasive and adhesive wear, breaking of lubrication film, patches, and fatigue regions for the different scan patterns were detailed in this study.

Investigation of corrosion and wear performance of TiNbTaZr/Cr-Mo PVD coatings on 316L SS in Hanks's solution for improved biomedical applications

316L stainless steel is popular due to its strength, durability, and especially cost-effectiveness in biomedical implant applications. However, the primary drawback of those materials is damage by corrosion and wear over prolonged exposure to the body's physiological environment. Thus, surface modification or coatings are essential to mitigate the corrosion and wear sensitivity of 316L implant materials. In this study, the corrosion and wear performance of TiNbTaZr/Cr-Mo PVD coatings on 316L stainless steel (SS) for improved biomedical applications have been investigated comprehensively. The coatings were deposited using an RF magnetron sputtering PVD system, and their morphological, structural, and wettability properties were characterized through SEM-EDS, GI-XRD, and contact angle measurements. The coatings' hardness was compared by using the Knoop hardness method and their surface roughness was analyzed by using a profilometer. Electrochemical corrosion tests and wear studies were conducted in both dry and simulated body fluid (SBF) conditions. The results indicated that the coatings exhibited nano-sized grain structures with no instances of delamination or cracking and consisted of a stable β-phase. The hardness of the coatings was significantly higher than that of the uncoated 316L sample. Contact angle measurements showed improved hydrophilicity for both coatings compared to uncoated 316L SS. Furthermore, the TNTZ-Mo coating demonstrated superior corrosion resistance and reduced wear under SBF conditions, making it a promising material for biomedical applications.

Study on the Effect of ELID Grinding on corrosion wear properties of Co-Cr Alloy

Contemporary Co-Cr alloys used in artificial joints can cause health complications in long-term applications. A pin-on-disc friction and wear testing instrument was used to evaluate the corrosion and abrasion of two types of Co-Cr alloys for artificial joints under simulated body fluid conditions after surface electrolytic composite grinding. Co-materials with lower carbon content displayed superior corrosion resistance than those materials with higher carbon content. Moreover, surface processing with electrolytic composite grinding produced a stable surface modification layer, which improved the surface hardness and formed an oxide film that inhibited metal ionization. The formation of precipitates in the corrosive environment is likely to improve the friction and wear properties of the material. As such, a variety of hardness was observed for the artificial joint friction disc and pin, especially when the hardness of the disc was higher than that of the pin, which can improve the friction and wear behavior of joints.

Fabrication of Zr-Ti-Si glassy metallic overlay on 3D printed Ti-6Al4V implant prototypes for enhanced biocompatibility

Implantable materials with enhanced corrosion resistance and bioactivity are highly desired for biomedical application. A 3D metal printed prototype surface was coated with amorphous alloy components of elements Zr, Ti and Si (Zr54Ti35 Si11) as a novel biomedical grade ternary system for the implants. A DC magnetron sputtering technique was used to sputter the films on Ti-6Al-4 V implant prototypes, exhibiting a smooth and denser coating with root means square surface roughness of 1.4 nm. Surface morphology and structural integrity of the thin film metallic glass (TFMG) was studied from electron microscopic techniques and X-ray diffraction analysis. The TFMG is thermally stable with a large supercooled liquid region (∆Tx) of 81.2 °C. Mechanical characteristics of the coatings were studied using the nanoindentation method to correlate the hardness and modulus of the implant materials. Under the simulated body fluid condition, Ti-6Al-4 V implant with 500 nm thickness coatings (Zr54Ti35Si11) exhibited the superior corrosion resistance rate 1 × 10−6 mpy with a charge transfer resistance of 34 kΩ promising for practical application. Electrochemical impedance spectra and Tafel analysis revealed that the corrosion resistance was prominent in the 500 nm thickness TFMG system than the 250 nm and uncoated bare counterparts. The in-vitro biocompatibility and cytotoxicity studies of the as-coated 3D printed implants were studied using the human osteoblast and L929 fibroblast cell lines, respectively. A hemocompatibility study on the implant materials revealed that erythrocytes remain biconcave without aggregation, platelet activation and thrombogenesis, supporting the biocompatibility of the implants. The integration of such unique properties makes these TFMG system ideal candidates for biomedical implants.

Microstructure, mechanical properties and fretting corrosion wear behavior of biomedical ZK60 Mg alloy treated by laser shock peening

ZK60 magnesium alloy was treated with laser shock peening (LSP) technology at different laser energy densities. Fretting corrosion wear tests were conducted on the LSP-treated and untreated magnesium alloy samples in simulated body fluid condition. The microstructure, residual stress, surface hardness, tensile strength, and corrosion resistance were also tested to analyze their relationships with fretting corrosion wear behavior. Results showed that a maximum of 73.4% reduction of the fretting corrosion wear volume can be obtained by LSP treatment. The fine grain strengthening and the strain hardening caused by dislocation and twinning, and the compressive residual stress improve the surface hardness, tensile strength, and corrosion resistance at the same time, thus reducing the fretting corrosion wear.

ZnO@ZIF-8 Nanoparticles as Nanocarrier of Ciprofloxacin for Antimicrobial Activity.

Numerous antimicrobial drugs have been prescribed to kill or inhibit the growth of microbes such as bacteria, fungi, and viruses. Despite the known therapeutic efficacy of these drugs, inefficient delivery could result in an inadequate therapeutic index and several side effects. In order to overcome this adversity, the present study investigated antibiotic drug loading in zeolitic imidazolate frameworks (ZIFs), in association with ZnO nanoparticles with known antimicrobial properties. In an economic synthesis method, the ZnO surface was first converted to ZIF-8 with 2-methylimidazole as a ligand, resulting in a ZnO@ZIF-8 structure. This system enables the high drug-loading efficiency (46%) of an antimicrobial drug, ciprofloxacin, within the pores of the ZIF-8. This association provides a control of the release of the active moieties, in simulated body-fluid conditions, with a maximum of 67% released in 96 h. The antibacterial activities of ZnO@ZIF-8 and CIP-ZnO@ZIF-8 were tested against the Gram-positive Staphylococcus aureus strain and the Gram-negative Pseudomonas aeruginosa strain, showing good growth inhibition. This result was obtained by combining ZnO@ZIF-8 with ciprofloxacin in a minimal inhibitory concentration (MIC) that was 10 times lower than ZnO@ZIF-8 for S. aureus and 200 times lower for P. aeruginosa, suggesting that CIP-ZnO@ZIF-8 may have potential application in prolonged antimicrobial treatment.

Bone-like apatite formation in phosphate-crosslinked sodium alginate-based hydrogels

• Posphate-crosslinked sodium alginate-based hydrogels was developed. • The hydrogels show interconnected porous networks. • The hydrogels show excellent bone-like apatite formation ability. Bioactive materials exhibiting bone-like apatite formation are crucial for inducing the osteogenic potentials of bone cells in the bone tissue engineering field. Herein, we report the design and synthesis of bioactive phosphate-crosslinked sodium alginate-based (PSA) hydrogels for biomineralization using a calcium-free approach. The hydrogels produced contained interconnected porous networks and exhibited improved swelling and biodegradable properties with excellent bone-like apatite formation abilities under simulated body fluid (SBF) conditions, which were attributed to the presence of phosphate groups. The devised functional phosphate-crosslinked sodium alginate hydrogels provided potential scaffolds for bone tissue engineering applications.

Characterization and investigation of properties of copper nanoparticle coated TiO2 nanotube surfaces on Ti6Al4V alloy

In this work, to investigate surface, corrosion and in vitro biological properties of the CuNPs-coated nanotube surfaces, antibacterial, bioactive and biocompatible nanoparticle-coated nanotube surfaces were produced on Ti6Al4V alloys by combined anodic oxidation (AO) and electrodeposition (ED) techniques for implant applications. All surfaces were characterized by SEM, EDX-mapping and -area, XRD, AFM and contact angle measurement techniques. The electrochemical and biological properties such as antibacterial activities, protein adsorption, ALP activity, hemolytic activity and cell viability of the surfaces were investigated in detail. Electrochemical corrosion resistance of CuNPs-coated nanotube surfaces were enhanced respect to uncoated Ti6Al4V alloy under simulated body fluid (SBF) conditions. Antibacterial properties, cell viability and ALP activity of CuNPs-coated nanotube surfaces were improved with compared to uncoated Ti6Al4V alloys. In addition, protein adsorption and hemolytic activity of CuNPs-coated nanotube surfaces were reduced. This work indicates a potential to precisely fabricate an antibacterial, bioactive and biocompatible CuNPs-coated nanotube surfaces on Ti6Al4V to fulfill orthopedic and dental implant needs by using combined AO and ED processes.

Novel low modulus beta-type Ti–Nb alloys by gallium and copper minor additions for antibacterial implant applications

This study aims to develop novel low-modulus, corrosion-resistant Ti-based alloys with enhanced antimicrobial properties for bone-related implant applications. Novel β-type (Ti–45Nb)-based alloys with minor additions of the antibacterial elements Ga and/or Cu (up to 4 wt.%) were produced by a two-step casting process followed by homogenization treatment. Three nominal compositions (Ti–45Nb)96-4 Ga, (Ti–45Nb)96–4Cu and (Ti–45Nb)96-2 Ga–2Cu (wt.%) were prepared based on alloy design approach using [Mo]eq and electron per atom (e/a) ratio. The influence of Ga and/or Cu addition on the phase constitution, mechanical response and corrosion characteristics in simulated body fluids (PBS, 37.5 °C) has been investigated. X-ray diffraction studies displayed a single β phase structure for all alloys, with an observed lattice contraction evidenced by the reduction of lattice parameters during Rietveld analysis. Homogenous equiaxed microstructures with grain sizes ranging from 55 μm up to 323 μm were observed for (Ti–45Nb)96-4 Ga, (Ti–45Nb)96-2 Ga–2Cu and (Ti–45Nb)96–4Cu alloys. The alloys displayed excellent plasticity with no cracking, or fracturing during compression tests. Their tensile strength, Young's modulus, maximum tensile strain and elastic energy were measured in the ranges of 544–681 MPa, 73–78 GPa, 17–28% and 2.5–3.7 MJ/m3, in the order (Ti–45Nb)96-4 Ga > (Ti–45Nb)96-2 Ga–2Cu > (Ti–45Nb)96–4Cu. In addition, it has been observed that micro-alloying Ti–Nb alloy with Ga and/or Cu posed no deleterious effect on the corrosion resistance in simulated body fluid conditions. The improvement in strength of the developed alloys has been discussed based on grain boundary and solid-solution strengthening, whereas the improved plasticity is attributed to work hardening.

MIL-100(Fe) Sub-Micrometric Capsules as a Dual Drug Delivery System.

Nanoparticles of metal–organic frameworks (MOF NPs) are crystalline hybrid micro- or mesoporous nanomaterials that show great promise in biomedicine due to their significant drug loading ability and controlled release. Herein, we develop porous capsules from aggregate of nanoparticles of the iron carboxylate MIL-100(Fe) through a low-temperature spray-drying route. This enables the concomitant one-pot encapsulation of high loading of an antitumor drug, methotrexate, within the pores of the MOF NPs, and the collagenase enzyme (COL), inside the inter-particular mesoporous cavities, upon the formation of the capsule, enhancing tumor treatment. This association provides better control of the release of the active moieties, MTX and collagenase, in simulated body fluid conditions in comparison with the bare MOF NPs. In addition, the loaded MIL-100 capsules present, against the A-375 cancer cell line, selective toxicity nine times higher than for the normal HaCaT cells, suggesting that MTX@COL@MIL-100 capsules may have potential application in the selective treatment of cancer cells. We highlight that an appropriate level of collagenase activity remained after encapsulation using the spray dryer equipment. Therefore, this work describes a novel application of MOF-based capsules as a dual drug delivery system for cancer treatment.