Search

• Proteins promote the formation of Ca/P-rich products on mg surface in static immersion. • Protein adsorption is largely reduced during mg degradation under flow condition. • Interaction between proteins and released ions/products is enhanced in solution under flow conditions. • Fluid flow leads to protein-accelerated degradation of mg. The interaction between organic molecules and biomaterial surfaces determines the fate of biomaterials during their service life, which is also the research hotspots in the field of biomaterials. To understand the mechanism of protein interaction with magnesium (Mg) degradation, alloying elements, immersion time, protein concentration and surface conditions have been previously considered for the effect of proteins on Mg degradation. However, fluid flow, as one of the critical factors, drew little attention in this case. In the present study, the effect of bovine serum albumin (BSA) and fetal bovine serum (FBS) on Mg degradation was compared under static and dynamic conditions. The results revealed that both BSA and FBS slightly decreased the degradation rate of Mg in Hanks' balanced salt solution (HBSS) under static immersion due to the protein adsorption and the formation of a Ca/P-rich top layer on Mg surface, whereas under dynamic flow condition the degradation of Mg was significantly accelerated in the presence of BSA or FBS. The reasons seemed to stem from the weakened protein adsorption on Mg surface in this case and the dynamically enhanced interaction between proteins and ions/products in solutions, which largely weaken the combination of the top Ca/P-rich layer with the inner corrosion product layer. These results highlight the importance of testing conditions for Mg characterization in vitro and the synergistic effect between different parameters on Mg degradation. [ABSTRACT FROM AUTHOR]

In this study, three new Schiff bases were synthesized from paeonol and amino acids to prepare a compound Schiff base coating on the Mg-Zn-Y-Nd alloy (ZE21B alloy) surface by electrostatic spraying, and these three single Schiff base coatings were prepared on the ZE21B alloy as control. The results of SEM and XPS confirmed the successful preparation of the coating. Immersion tests and electrochemical tests showed that both the single coating and the compound coating significantly improved the corrosion resistance of ZE21B alloy, and the compound coating could play a synergistic corrosion inhibition effect, thus showing the best corrosion resistance. [ABSTRACT FROM AUTHOR]

Considering the excellent biocompatibility of magnesium (Mg) alloys and their better mechanical properties compared to polymer materials, a wrought MgZnCa alloy with low contents of Zn (0.7 wt%) and Ca (0.6 wt%) (ZX11) was developed by twin roll casting (TRC) technology as potential biodegradable bone plates. The degradability and cell response of the ZX11 alloy were evaluated in vitro , as well as the mechanical integrity according to tensile tests after immersion. The results revealed a slightly higher degradation rate for the rolled ZX11, in comparison to that of the annealed one. It was mainly caused by the deformation twins and residual strain stored in the rolled alloy, which also seemed to promote localized degradation, thereby leading to a relatively fast deterioration in mechanical properties, especially the fracture strain/elongation. In contrast, after the annealing treatment, the alloy showed relatively lower strength, yet a lower degradation rate and quite stable elongation during the initial weeks of immersion were observed. More importantly, the ZX11 alloy, regardless of the annealing treatment, showed good in vitro cytocomopatibility regarding human primary osteoblasts. The assessment indicates the rolled alloy as a good choice for implantation sites where relatively high mechanical strength is needed during the early implantation, while the annealed alloy is a potential candidate for the sites which demand stable mechanical integrity during service. The development of magnesium alloys as bone implants demands low degradation rate to gain not only a slow hydrogen evolution, but also a stable mechanical integrity during service. The present study develops a micro-alloyed MgZnCa alloy via twin roll casting (TRC) technology. It exhibited limited cytotoxicity, fairly low degradation rate and comparable strength to the reported Mg-1Zn-5Ca alloy which has been used as bone screws in clinical trials, indicating the great potential application as biodegradable bone implants. Furthermore, it showed good mechanical integrity during immersion to support the defect healing. Our results can aid other researchers to evaluate the mechanical integrity of biodegradable materials and to pay more attention to the effect of degradation behaviour on mechanical integrity of materials. [ABSTRACT FROM AUTHOR]

Zinc (Zn)-based alloys have been investigated as one kind of promising degradable metallic biomaterials. Nevertheless, the mechanical and corrosion properties of Zn alloys still need to be improved to meet the demands of biodegradable implants. In this study, Zn1Mg alloy (1 wt%) was studied as the base alloy with adding varied amounts of zirconium (Zr), and both casting and extrusion were employed to treat the developed alloys. The results revealed that the addition of Zr refined the microstructure of Zn1Mg, which consisted of Zn primary dendrite, eutectic mixtures of Zn and Mg 2 Zn 11 , and a new formed particle precipitation (Zn 22 Zr). The finer microstructure accordingly improved the mechanical properties and the corrosion resistance of the alloys. Although the effect of Zr on the mechanical properties was largely minimized by extrusion process, Zr further enhanced the corrosion resistance and led to more uniform corrosion for the extruded alloys. • Novel ternary Zn1MgZr alloys were developed as potential degradable metallic biomaterials. • The addition of Zr refines the microstructure of as-cast Zn1MgZr alloys. • The anti-corrosion properties of Zn1Mg alloys are enhanced by the addition of Zr. • The addition of Zr leads to more uniform degradation for the extruded alloys. • Extrusion process weakens the influence of Zr due to more homogenous microstructure. [ABSTRACT FROM AUTHOR]

• Bio-based nanocomposite film forming inhibitor for rebar concrete structure. • The corrosion resistance increases with time. • It has self-healing property. • The film forming process is industrial feasible. A mussel adhesive protein based nanocomposite thin film was produced to be applied as surface pre-treatment or primer on rebars of reinforced concrete. The film deposition and drying processes were investigated to enhance the corrosion protection, and facilitate large-scale industrial applications. The morphology, chemical composition and microstructure of the film were characterised with SEM, EDS, Micro-IR and AFM techniques. EIS results suggested the film provides excellent and increased corrosion protection for the carbon steel in mild and extreme concrete pore solutions. In-situ AFM results demonstrated the self-healing ability of the film to the pitting corrosion. [ABSTRACT FROM AUTHOR]

• Surface modification on Zn-1Mg for regulating the degradation and biocompatibility. • Grafting PCCs on Zn-1Mg surface, using a silane (APTEs) modification method. • ZM-Si-PCCs shows 2 order higher film resistance than Zn-1Mg in SBF during 24h. • ZM-Si-PCCs exhibited enhanced hemocompatibility and cyto-compatibility for HUVECs. • The decreased release of Zn2+ is the main reason for improved biocompatibility. With the purpose of regulating corrosion behavior and improving the biocompatibility of Zn-1 Mg alloy, we developed a phosphorylcholine chitosan (PCCs) coating forming a bionic cell membrane surface, using a silane conversion layer (APTEs) as the connection layer. Atomic force microscopy (AFM), contact angle (CA), and nano-scratch tests were conducted to study the surface roughness, the hydrophilicity and the adhesion strength of the PCCs layer. Bonding details were investigated by X-ray photoelectron spectroscopy (XPS) and Fourier Transform infrared spectroscopy (FTIR). Electrochemical impedance spectroscopy (EIS) tests were performed in simulated body fluid (SBF) at 37 °C to understand the degradation behavior in vitro. The experimental results demonstrated that the PCCs coating remarkably increased resistance against corrosion attack, with approximately 2 order higher value of the film resistance (R f) than that of the substrate. Simultaneously, the PCCs-modified surface exhibited improved blood compatibility, anti-platelet adhesion, and significantly enhanced cyto-compatibility for human vascular endothelium cells (HUVECs). These results relates to the decreased release of Zn2+ and the considerably enhanced surface hydrophilicity. PCCs coated Zn alloys presented in this work are indeed showing the promise for future application in biodegradable vascular stent. [ABSTRACT FROM AUTHOR]