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• A multifunctional coating was constructed on ZE21B alloy for biodegradable vascular stents. • MgF 2 layer and hydrophilic polymers in the functional coating could effectively protect ZE21B alloy from overfast degradation. • Anticoagulant ACH 11 peptides and ECs-selective REDV peptides in the functional coating could dramatically enhance the hemocompatibility and pro-endothelialization capacity of ZE21B alloy. • The functional coating systematically improved the corrosion resistance and biocompatibility of ZE21B alloy in vitro and in vivo. Biodegradable magnesium alloy stents (MAS) have great potential in the treatment of cardiovascular diseases. However, too fast degradation and the poor biocompatibility are still two key problems for the clinical utility of MAS. In the present work, a functional coating composed of hydrophilic polymers and bioactive peptides was constructed on magnesium alloy to improve its corrosion resistance and biocompatibility in vitro and in vivo. Mg-Zn-Y-Nd (ZE21B) alloy modified with the functional coating exhibited moderate surface hydrophilicity and enhanced corrosion resistance. The favourable hemocompatibility of ZE21B alloy with the functional coating was confirmed by the in vitro blood experiments. Moreover, the modified ZE21B alloy could selectively promote the adhesion, proliferation, and migration of endothelial cells (ECs), but suppress these behaviors of smooth muscle cells (SMCs). Furthermore, the modified ZE21B alloy wires could alleviate intimal hyperplasia, enhance corrosion resistance and re-endothelialization in vivo transplantation experiment. These results collectively demonstrated that the functional coating improved the corrosion resistance and biocompatibility of ZE21B alloy. This functional coating provides new insight into the design and development of novel biodegradable stents for biomedical engineering. [ABSTRACT FROM AUTHOR]

Magnesium (Mg) alloys are promising materials for cardiovascular stent applications due to their good biocompatibility and biodegradability. However, in vitro and in vivo corrosion tests reveal that Mg alloy stents suffer from a rapid corrosion rate and severe localized corrosion, which is limiting their widespread application. To solve the problem of uneven degradation of stents, a HTHE (long-time and high-temperature heat treatment, large-reduction-ratio hot extrusion) process is used to manufacture Mg-Zn-Y-Nd alloy microtubes in this study. The heat treatment is to dissolve alloying elements and reduce the size of SPPs, and the hot extrusion is to acquire fine-grained and strongly textured microtubes. The microstructural characterization shows that coarse second phases in as-cast alloy are refined and uniformly distributed in matrix of microtubes. After hot extrusion, microtubes show strong texture with basal plain oriented parallel to the longitudinal section (LS). The corrosion testing indicates that severe localized corrosion occurs on the cross section (CS) while localized corrosion is alleviated on the LS. Based on the different corrosion properties of the LS and CS, HTHEed microtubes are promising for solving the problems of rapid corrosion rate and severe localized corrosion of Mg alloy stents. [ABSTRACT FROM AUTHOR]

Tool coatings exhibit different tribological behavior when cutting dissimilar materials, and understanding the differences is crucial for their service life. In this study, CrAlN/TiSiN multilayer coating was deposited by the arc ion plating technique, and its microstructure, load-bearing capacity, and toughness were investigated as well as the tribological behavior of the coating sliding against 7A09 Al alloy and GCr15 bearing steel at different temperatures. The results indicated a high fluctuation in the friction coefficient between the coating and 7A09 Al alloy above 150 °C, and the coating exhibited a negative wear rate. The friction coefficient between the coating and GCr15 bearing steel shows a decreasing trend above 150 °C, and the wear surface of the coating showed a smooth morphology. [ABSTRACT FROM AUTHOR]

The localized corrosion caused by the interphase potential differences and incompleteness of the corrosion product layer results in the premature failure of Mg alloys. In biomedical applications, understanding about the corrosion behavior of Mg alloys in complex environment is still insufficient. In this work, mechanical tests after corrosion were employed to indirectly but generally reflect the localized corrosion of Mg alloy in the protein-containing electrolytes. The results reveal that protein alters the Mg corrosion mode to uniform corrosion and an appropriate amount of protein is beneficial for maintaining its mechanical bearing capacity. This work is helpful for understanding the corrosion behavior of Mg alloys and consummating degradation evaluation systems for Mg alloys. [Display omitted] • Mechanical tests after corrosion is employed to indirectly but generally reflect the localized corrosion of Mg alloy. • The complexation of BSA and Mg2+/Ca2+ leads to the uniform corrosion of Mg alloy. • BSA increases the corrosion rate of Mg alloy but the decline of mechanical properties is less. • Corrosion tests in simple media probably do not accurately reflect the actual service performance of Mg alloy. [ABSTRACT FROM AUTHOR]

Highlights: [•] It’s effective to fabricate a bio-composite coating on Mg alloy by this method. [•] Most HA got involved in the coating and turned into TCP during the MAO process. [•] HA and the sintering-caused phases changed the cross-section into dense structure. [•] The bioactivity and corrosion resistance of the coating were improved. [ABSTRACT FROM AUTHOR]

To build a suitable corrosion environment for testing the degradation behavior of magnesium alloy in vitro, the medium and test environment are constantly optimized. However, the applicability of medium renewal mode is still vague. In this study, based on three representative test protocols, the influence of the specific ratio of media volume to surface area and the disposable medium real-time renewal mode (flow-through) on Mg corrosion were investigated. It is found that in flow-through medium renewal mode, the composition of the medium is maintained quasi-constant which is essential for corrosion tests. The selection suggestion on medium renewal mode was also proposed. This work is beneficial for ultimately establishing the representative in vitro testing protocols for Mg bioabsorbable materials. • The ratio of medium volume to surface area affects Mg corrosion. • The disposable medium real-time renewal mode maintains the medium stability. • Different media and materials have distinct sensitivity to medium renewal modes. • Medium renewal modes of corrosion test should be prudently selected based on actual needs. [ABSTRACT FROM AUTHOR]

• Yttrium-oxygen layer is found under dynamic flow. • Yttrium-oxygen layers decreases the corrosion rate of microtubes under dynamic flow. • A suitable selection of rare earth elements could further improve the corrosion resistance. In the corrosion tests, yttrium (Y) element reacts with oxygen (O) element to form Y-O compound, generating a protective corrosion layer to isolate magnesium (Mg) alloy from further attack of corrosion medium. To better illustrate the protective effects of Y-O compound on corrosion morphology of biodegradable Mg alloys stents, in vitro dynamic corrosion tests were conducted for ZE21B Mg alloy microtubes. Under dynamic flow, Mg-O layer and calcium-phosphate (Ca-P) layer peeled off from microtubes, and the compact and flat Y-O layer started to emerge, protecting ZE21B Mg alloy microtubes against flow induced corrosion. [ABSTRACT FROM AUTHOR]

The development of multifunctional Mg-based active implants with controllable degradation and antibacterial capabilities has become a hotspot in the research field of biodegradable metallic materials. To this end, a BN nanosheets (BNNS) _ vancomycin (Van) @ chitosan (CS) nanocomposite coating containing two antibacterial components (BNNS and Van) was prepared on Mg alloys via a micro-arc oxidation (MAO) pre-treatment combined with following electrodeposition. The related characterizations of the coating show that the composite coating has a high roughness, hydrophobicity and fair corrosion resistance. In vitro antibacterial experiments show that the BNNS_Van@CS/MAO composite coating have obvious inhibitory effect on the growth of both E. coli and S. aureus. The antibacterial effect of the BNNS_Van@CS/MAO composite coating was attributed to the synergistic effect of CS, BNNS and Van. This study provides a valuable surface modification strategy for developing multifunctional Mg-based implants with good corrosion resistance and antibacterial properties. [Display omitted] • BNNS@CS-loaded vancomycin composite coatings were prepared on ZE21C alloy. • BNNS_Van@CS/MAO coating provides an effective protection for the ZE21C alloy. • BNNS_Van@CS/MAO coating has good antibacterial effect against E.coli and S.aureus. • BNNS@CS coating and vancomycin have synergistic antibacterial effects. [ABSTRACT FROM AUTHOR]

Abstract: Biodegradable magnesium alloys are potential for bone implants. In order to improve the corrosion resistance and the surface bioactivity of Mg–Zn–Ca alloy, a composite coating which had high adhesion strength with the substrate was prepared on Mg–Zn–Ca alloy through combined micro-arc oxidation and electrochemical deposition. The composite coating had needle-like structure and consisted of MgO, Mg3(PO4)2, hydroxyapatite and octacalcium phosphate. The thickness of the composite coating was about 12–15μm and the adhesion strength of the optimum composite coating with the substrate was higher than 40MPa. The potentiodynamic polarization and hydrogen evolution tests in simulated body fluid indicated that the composite coating significantly improved the corrosion resistance of the substrate. Deposition of Ca/P salt on the composite coating showed good surface bioactivity of the composite coating in hydrogen evolution tests. The compression tests of the composite coating modified alloy immersed in simulated body fluid for different time revealed that it could meet requirement of bone implant materials in the initial bone reunion period. Thus, the surface modification of the composite coating greatly enhanced the potential of magnesium and its alloy as degradable implants. [Copyright &y& Elsevier]

• Three Schiff bases as new corrosion inhibitors for Mg alloy were synthesized. • The Schiff bases could effectively control the degradation rate of Mg alloy. • The inhibition mechanism is that Schiff bases complex with Mg2+ to form complexes. • Providing a new reference for the controlled degradation of bio-magnesium alloys. In this research, three new Schiff bases were synthesized by paeonol and amino acids and tested as corrosion inhibitors for Mg-Zn-Y-Nd alloy. Weight loss measurements and electrochemical measurements demonstrated that three Schiff bases showed high inhibition efficiency on Mg corrosion. The corrosion products on Mg surface were analyzed by scanning electron microscopy (SEM), Fourier transform infrared spectrum (FTIR) and X-ray photoelectron spectroscopy (XPS). The possible inhibition mechanism was proposed, in which the Schiff bases react with Mg2+ ions to form complexes on Mg surface in inhibitors-containing electrolytes. The theoretical calculation of quantum chemical demonstrated the experimental findings. [ABSTRACT FROM AUTHOR]