Screening on binary Zr-1X (X = Ti, Nb, Mo, Cu, Au, Pd, Ag, Ru, Hf and Bi) alloys with good in vitro cytocompatibility and magnetic resonance imaging compatibility

Elastin-like recombinamer-mediated hierarchical mineralization coatings on Zr-16Nb-xTi (x = 4,16 wt%) alloy surfaces improve biocompatibility

The biocompatibility of biomedical materials is vital to their applicability and functionality. However, modifying surfaces for enhanced biocompatibility using traditional surface treatment techniques is challenging. We employed a mineralizing elastin-like recombinamer (ELR) self-assembling platform to mediate mineralization on Zr-16Nb-xTi (x = 4,16 wt%) alloy surfaces, resulting in the modification of surface morphology and bioactivity while improving the biocompatibility of the material. We modulated the level of nanocrystal organization by adjusting the cross-linker ratio. Nanoindentation tests revealed that the mineralized configuration had nonuniformity with respect to Young's modulus and hardness, with the center areas having higher values (5.626 ± 0.109 GPa and 0.264 ± 0.022 GPa) compared to the edges (4.282 ± 0.327 GPa and 0.143 ± 0.023 GPa). The Scratch test results indicated high bonding strength (2.668 ± 0.117 N) between the mineralized coating and the substrate. Mineralized Zr-16Nb-xTi (x = 4,16 wt%) alloys had higher viability compared to untreated alloys, which exhibited high cell viability (>100 %) after 5 days and high alkaline phosphatase activity after 7 days. Cell proliferation assays indicated that MG 63 cells grew faster on mineralized surfaces than on untreated surfaces. Scanning electron microscopy imaging confirmed that the cells adhered and spread well on mineralized surfaces. Furthermore, hemocompatibility test results revealed that all mineralized samples were non-hemolytic. Our results demonstrate the viability of employing the ELR mineralizing platform to improve alloy biocompatibility.

Osteogenesis and angiogenesis of a bulk metallic glass for biomedical implants

Implantation is an essential issue in orthopedic surgery. Bulk metallic glasses (BMGs), as a kind of novel materials, attract lots of attentions in biological field owing to their comprehensive excellent properties. Here, we show that a Zr61Ti2Cu25Al12 (at. %) BMG (Zr-based BMG) displays the best cytocompatibility, pronounced positive effects on cellular migration, and tube formation from in-vitro tests as compared to those of commercial-pure titanium and poly-ether-ether-ketone. The in-vivo micro-CT and histological evaluation demonstrate the Zr-based BMG can significantly promote a bone formation. Immunofluorescence tests and digital reconstructed radiographs manifest a stimulated effect on early blood vessel formation from the Zr-based BMG. Accordingly, the intimate connection and coupling effect between angiogenesis and osteogenesis must be effective during bone regeneration after implanting Zr-based BMG. Dynamic gait analysis in rats after implanting Zr-based BMG demonstrates a tendency to decrease the pain level during recovery, simultaneously, without abnormal ionic accumulation and inflammatory reactions. Considering suitable mechanical properties, we provide a realistic candidate of the Zr61Ti2Cu25Al12 BMG for biomedical applications.

Enhancement of mechanical properties and shape memory effect of Ti-Cr-based alloys via Au and Cu modifications

The requirements for biomedical materials have been raised greatly due to the rapidly aging global population. Shape memory alloys (SMAs) are indeed promising materials for biomedical applications due to their controllable shape deformation via the manipulation of temperature and/or stress. This study investigated the enhancement of the fundamental mechanical properties and the shape memory effect (SME) in the Ti-Cr-based alloys via the modification of Au and Cu. The quaternary Ti-Cr-Au-Cu alloys were successfully manufactured by physical metallurgy methods and their phase constitutions, mechanical properties, SME, and superelastic (SE) behaviors have been investigated in this study. Cold-workability, which was enhanced by the introduction of the Au element, was elaborated by the phase constitutions of the alloys. The β-parent phase was stabilized to around body temperature by the introduction of the β-stabilizers of Cr, Au, and Cu, and the functionalities of the specimens were revealed at the operating temperature. Perfect SME at the shape recovery rate of 100% was practiced by the substitution of Au by Cu and the mechanical properties, such as strength and ductility, were also enhanced. Functional mappings of the fundamental mechanical properties, which could be a helpful tool for the investigations of the quaternary Ti-Cr-Au-Cu alloys, were constructed in this work.

Manganese porphyrin-based metal-organic framework for synergistic sonodynamic therapy and ferroptosis in hypoxic tumors

Development of efficient therapeutic strategy to incorporate ultrasound (US)-triggered sonodynamic therapy (SDT) and ferroptosis is highly promising in cancer therapy. However, the SDT efficacy is severely limited by the hypoxia and high glutathione (GSH) in the tumor microenvironment, and ferroptosis is highly associated with reactive oxygen species (ROS) and GSH depletion.

Methods: A manganese porphyrin-based metal-organic framework (Mn-MOF) was constructed as a nanosensitizer to self-supply oxygen (O₂) and decrease GSH for enhanced SDT and ferroptosis. In vitro and in vivo analysis, including characterization, O₂ generation, GSH depletion, ROS generation, lipid peroxidation, antitumor efficacy and tumor immune microenvironment were systematically evaluated.

Results: Mn-MOF exhibited catalase-like and GSH decreasing activity in vitro. After efficient internalization into cancer cells, Mn-MOF persistently catalyzed tumor-overexpressed H₂O₂ to in-situ produce O₂ to relieve tumor hypoxia and decrease GSH and GPX4, which facilitated the formation of ROS and ferroptosis to kill cancer cells upon US irradiation in hypoxic tumors. Thus, strong anticancer and anti-metastatic activity was found in H22 and 4T1 tumor-bearing mice after a single administration of Mn-MOF upon a single US irradiation. In addition, Mn-MOF showed strong antitumor immunity and improved immunosuppressive microenvironment upon US irradiation by increasing the numbers of activated CD8⁺ T cells and matured dendritic cells and decreaing the numbers of myeloid-derived suppressor cells in tumor tissues.

Conclusions: Mn-MOF holds great potential for hypoxic cancer therapy.

Novel Biocompatible Zr-Based Alloy with Low Young's Modulus and Magnetic Susceptibility for Biomedical Implants

The microstructure, mechanical properties, magnetic susceptibility, electrochemical corrosion performance, in vitro cell compatibility and blood consistency of Zr-16Nb-xTi (x = 0, 4, 8, 12 and 16 wt.%) materials were investigated as potential materials for biomedical implants. X-ray diffraction (XRD) and Transmission electron microscopy (TEM) analyses revealed the secondary phase martensite α' formed during the quenching process. The phase composition contained metastable β and martensite α', resulting from Ti addition. These phase constitutions were the main causes of a low Young's modulus and magnetic susceptibility. The in vitro cytocompatibility analysis illustrated that the MG63 cells maintained high activity (from 91% to 97%) after culturing in Zr-16Nb-xTi extraction media for 12 days due to the high internal biocompatibility of Zr, Nb and Ti elements, as well as the optimal corrosion resistance of Zr-16Nb-xTi. On the basis of Inductively coupled plasma optical emission spectrometry (ICP-OES) ion release studies, the concentration of Zr, Nb and Ti was noted to reach the equipment detective limit of 0.001 mg/L, which was much lower than pure Ti. With respect to the corrosion behavior in Hank's solution, Zr-16Nb-16Ti displayed superior properties, possessing the lowest corrosion current density and widest passivation region, attributed to the addition of Ti. The blood compatibility test illustrated that the Zr-16Nb-xTi materials were nonhemolytic, and the platelets maintained a spherical shape, with no aggregation or activation on Zr-16Nb-xTi. Overall, Ti addition has obvious effects on the developed Zr-16Nb-xTi alloys, and Zr-16Nb-4Ti exhibited low magnetic susceptibility, low modulus, good biocompatibility and proper corrosion properties, demonstrating the potential of use as implant biomaterials.

Biocompatibility and degradation of gold-covered magneto-elastic biosensors exposed to cell culture

Magneto-elastic materials (ME) have important advantages when applied as biosensors due to the possibility of wireless monitoring. Commercial Metglas 2826MB3™ (FeNiMoB) is widely used, however sensor stabilization is an important factor for biosensor performance. This study compared the effects of biocompatibility and degradation of the Metglas 2826MB3™ alloy, covered or not with a gold layer, when in contact with cell culture medium. Strips of amorphous Metglas 2826MB3™ were cut and coated with thin layers of Cr and Au, as verified by Rutherford Backscattering Spectroscopy (RBS). Using Inductively Coupled Plasma-Optical Emission Spectrometry (ICP-OES), the presence of metals in the culture medium was quantitatively determined for up to seven days after alloy exposure. Biocompatibility of fibroblast Chinese Hamster Ovary (CHO) cultures was tested and cytotoxicity parameters were investigated by indirect means of reduction of MTT (3-(4,5-dimethylthiazol-2-yl)-2,5-diphenyltetrazolium bromide) at 1, 2 and 7 days. Cell death was further evaluated through in situ analysis using Acridine Orange/Ethidium Bromide (AO/EB) staining and images were processed with ImageJ software. Ions from Metglas(®) 2826MB3™ induced a degradation process in living organisms. The cytotoxicity assay showed a decrease in the percentage of live cells compared to control for the ME strip not coated with gold. AO/EB in situ staining revealed that most of the cells grown on top of the gold-covered sensor presented a normal morphology (85.46%). Covering ME sensors with a gold coating improved their effectiveness by generating protection of the transducer by reducing the release of ions and promoting a significant cell survival.

Design and development of novel MRI compatible zirconium- ruthenium alloys with ultralow magnetic susceptibility

In the present study, novel MRI compatible zirconium-ruthenium alloys with ultralow magnetic susceptibility were developed for biomedical and therapeutic devices under MRI diagnostics environments. The results demonstrated that alloying with ruthenium into pure zirconium would significantly increase the strength and hardness properties. The corrosion resistance of zirconium-ruthenium alloys increased significantly. High cell viability could be found and healthy cell morphology observed when culturing MG 63 osteoblast-like cells and L-929 fibroblast cells with zirconium-ruthenium alloys, whereas the hemolysis rates of zirconium-ruthenium alloys are <1%, much lower than 5%, the safe value for biomaterials according to ISO 10993-4 standard. Compared with conventional biomedical 316L stainless steel, Co–Cr alloys and Ti-based alloys, the magnetic susceptibilities of the zirconium-ruthenium alloys (1.25 × 10⁻⁶ cm³·g⁻¹–1.29 × 10⁻⁶ cm³·g⁻¹ for zirconium-ruthenium alloys) are ultralow, about one-third that of Ti-based alloys (Ti–6Al–4V, ~3.5 × 10⁻⁶ cm³·g⁻¹, CP Ti and Ti–6Al–7Nb, ~3.0 × 10⁻⁶ cm³·g⁻¹), and one-sixth that of Co–Cr alloys (Co–Cr–Mo, ~7.7 × 10⁻⁶ cm³·g⁻¹). Among the Zr–Ru alloy series, Zr–1Ru demonstrates enhanced mechanical properties, excellent corrosion resistance and cell viability with lowest magnetic susceptibility, and thus is the optimal Zr–Ru alloy system as therapeutic devices under MRI diagnostics environments.

Intraocular foreign bodies: A review

Intraocular foreign body injuries may result in a wide range of intraocular pathology and visual outcomes based on the mechanism of injury, type of foreign body, and subsequent complications. We have reviewed the literature to describe the epidemiology and mechanisms of such injuries; types of foreign bodies; imaging tools for diagnosis; current trends in management, presurgical, and surgical interventions; as well as visual prognosis and potential complications. The purpose of this review is to familiarize clinicians with the recent advances in diagnosis and management of such injuries.

Microstructure, mechanical properties, castability and in vitro biocompatibility of Ti-Bi alloys developed for dental applications

In this study, the microstructure, mechanical properties, castability, electrochemical behaviors, cytotoxicity and hemocompatibility of Ti-Bi alloys with pure Ti as control were systematically investigated to assess their potential applications in the dental field. The experimental results showed that, except for the Ti-20Bi alloy, the microstructure of all other Ti-Bi alloys exhibit single α-Ti phase, while Ti-20Bi alloy is consisted of mainly α-Ti phase and a small amount of BiTi2 and BiTi3 phases. The tensile strength, hardness and wear resistance of Ti-Bi alloys were demonstrated to be improved monotonically with the increase of Bi content. The castability test showed that Ti-2Bi alloy increased the castability of pure Ti by 11.7%. The studied Ti-Bi alloys showed better corrosion resistance than pure Ti in both AS (artificial saliva) and ASFL (AS containing 0.2% NaF and 0.3% lactic acid) solutions. The concentrations of both Ti ion and Bi ion released from Ti-Bi alloys are extremely low in AS, ASF (AS containing 0.2% NaF) and ASL (AS containing 0.3% lactic acid) solutions. However, in ASFL solution, a large number of Ti and Bi ions are released. In addition, Ti-Bi alloys produced no significant deleterious effect to L929 cells and MG63 cells, similar to pure Ti, indicating a good in vitro biocompatibility. Besides, both L929 and MG63 cells perform excellent cell adhesion ability on Ti-Bi alloys. The hemolysis test exhibited that Ti-Bi alloys have an ultra-low hemolysis percentage below 1% and are considered nonhemolytic. To sum up, the Ti-2Bi alloy exhibits the optimal comprehensive performance and has great potential for dental applications.