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Magnesium (Mg) and its alloys exhibit great potential in clinical applications owing to the outstanding biological performance and excellent mechanical properties, whereas the quick corrosion rate in the physiological environment has limited their further clinical application. In this work, we designed and developed a multifunctional polypyrrole/zinc oxide (Ppy/ZnO) composite coating by cyclic voltammetry method, aiming to enhance the biocorrosion resistance, biocompatibility and antibacterial property of the Mg alloys. The electrochemical and immersion tests indicated that the corrosion resistance of the Mg alloy was improved significantly by the composite coating. A systematic in vitro investigation of cellular response confirmed that the composite coating significantly promoted the adhesion and proliferation of cells. In addition, the composite coating showed a remarkable antibacterial ability of 96.5 ± 2.6 % against Escherichia coli (E.coli). The enhanced corrosion resistance, cytocompatibility, and antibacterial property of the Ppy/ZnO coated Mg alloy makes it a promising candidate as orthopedic implants material., Competing Interests: Declaration of Competing Interest The authors declare that they have no known competing financial interests or personal relationships that could have appeared to influence the work reported in this paper., (Copyright © 2020 Elsevier B.V. All rights reserved.)

As a degradable metal, zinc (Zn) has attracted an immense amount of interest as the next generation of bioresorbable implants thanks to its modest corrosion rate and its vital role in bone remodeling, yet very few studies have thoroughly investigated its functionality as a porous implant for bone tissue engineering purposes. Zn bone scaffolds with two different pore sizes of 900 μm and 2 mm were fabricated using additive manufacturing-produced templates combined with casting. The compressive properties, corrosion rates, biocompatibility, and antibacterial performance of the bioscaffolds were examined and compared to a non-porous control. The resulting textured and porous Zn scaffolds exhibit a fully interconnected pore structure with precise control over topology. As pore size and porosity increased, mechanical strength decreased, and corrosion rate accelerated. Cell adhesion and growth on scaffolds were enhanced after an ex vivo pretreatment method. In vitro cellular tests confirmed good biocompatibility of the scaffolds. As porosity increased, potent antibacterial rates were also observed. Taken together, these results demonstrate that Zn porous bone scaffolds are promising for orthopedic applications., Competing Interests: Declaration of competing interest The authors declare that they have no known competing financial interests or personal relationships that could have appeared to influence the work reported in this paper., (Copyright © 2020 Elsevier B.V. All rights reserved.)

Zinc (Zn) has recently emerged as a promising biodegradable metal thanks to its critical physiological roles and promising degradation behavior. However, cytocompatibility and antibacterial property of Zn is still suboptimal, in part, due to the excessive Zn ions released during degradation. Inspired by the calcium phosphate-based minerals in natural bone tissue, zinc phosphate (ZnP) coatings were prepared on pure Zn using a chemical conversion method in this study. The coating morphology was then optimized through controlling the pH of coating solution, resulting in a homogeneous micro-/nano-ZnP coating structure. The ZnP coating significantly increased the cell viability, adhesion, and differentiation of pre-osteoblasts and vascular endothelial cells, while significantly reduced the adhesion of the platelets and E. coli. Additionally, ZnP coating significantly reduced the Zn ion release from the bulk material during degradation process, resulting in a much lower Zn 2+ concentration and pH change in the surrounding environment. The improved hemocompatibility, cytocompatibility and antibacterial performance of ZnP coated Zn biomaterials could be mainly attributed to the controlled Zn ion release and micro-/nano-scaled coating structure. Taken together, ZnP coating on Zn-based biomaterial appears to be a viable approach to enhance its biocompatibility and antibacterial property as well as to control its degradation rate. Statement of Significance Zn and its alloys are promising biodegradable implant materials for orthopedic and cardiovascular applications. However, notable cytotoxicity has been reported due to degradation products accumulated in the local environment, largely overdosed Zn 2+ . Thus, controlling burst Zn 2+ release is the key to minimize the toxicity of Zn implants. To achieve this goal, we prepared a homogenous ZnP coating on Zn metals thanks to its easy synthesis, stable chemical property, and good biocompatibility. Results showed that ZnP not only improved the cell viability, adhesion and proliferation, but also significantly reduced the attachment of platelet and bacterial. Therefore, ZnP could be a promising approach to improve the functional performance of Zn-based implants, and potentially be applied to many other medical implants., (Copyright © 2019. Published by Elsevier Ltd.)

Zinc (Zn)-based alloys are considered a new class of biodegradable implant materials due to their superior chemical stability and processability compared to biodegradable magnesium (Mg) alloys. In this study, we report a new biodegradable Zn-5Ge alloy with highly desirable mechanical, corrosion, and biological properties. Microstructural characterization revealed the effective grain-refining effect of germanium (Ge) on the Zn alloy. Tensile test results indicated that the hot-rolled Zn-5Ge alloy showed an ultimate tensile strength of 237.0 MPa, a yield strength of 175.1 MPa, and an elongation of 21.6%; while as-cast pure Zn showed an ultimate tensile strength of 33.6 MPa, a yield strength of 29.3 MPa, and an elongation of 1.2%. The corrosion rates measured by potentiodynamic polarization tests in Hank's solution in ascending order are: as-cast Zn-5Ge (0.1272 mm/y) < as-cast pure Zn (0.1567 mm/y) < hot-rolled Zn-5Ge (0.2255 mm/y) < hot-rolled pure Zn (0.3057 mm/y). Immersion tests revealed that the degradation rate of as-cast Zn-5Ge is 0.042 mm/y, less than half of that of hot-rolled pure Zn and ∼62% of that of as-cast pure Zn. Moreover, the Zn-5Ge alloy showed excellent in vitro hemocompatibility and the addition of 5% Ge effectively enhanced the hemocompatibility of pure Zn. CCK-8 assay using murine preosteoblast MC3T3-E1 cells indicated that the diluted extracts at a concentration <12.5% of both the as-cast Zn-5Ge alloy and pure Zn showed grade 0 cytotoxicity; the diluted extracts at the concentrations of 50% and 25% of Zn-5Ge alloy showed a significantly higher cell viability than those of pure Zn. STATEMENT OF SIGNIFICANCE: Zinc (Zn)-based alloys are currently considered a new class of biodegradable implant materials due to their excellent processability. Here, we report a novel Zn-5Ge alloy with highly desirable mechanical, corrosion and biological properties. The tensile test results indicated that the hot-rolled Zn-5Ge alloy showed an ultimate tensile strength of 237.0 MPa, a yield strength of 175.1 MPa and an elongation of 21.6%; while as-cast pure Zn showed an ultimate tensile strength of 33.6 MPa, a yield strength of 29.3 MPa and an elongation of 1.2%. The corrosion rate measured by potentiodynamic polarization tests in Hank's solution in the ascending order is: as-cast Zn-5Ge (0.1272 mm/y) < as-cast pure Zn (0.1567 mm/y) < hot-rolled Zn-5Ge (0.2255 mm/y) < hot-rolled pure Zn (0.3057 mm/y). Immersion tests revealed that the degradation rate of the as-cast Zn-5Ge is 0.042 mm/y, less than half of that of the hot-rolled pure Zn, ∼62% of that of as-cast pure Zn. Moreover, the Zn-5Ge alloy showed excellent in vitro biocompatibility., (Copyright © 2018 Acta Materialia Inc. Published by Elsevier Ltd. All rights reserved.)

Metallic biomaterials are widely used for clinical applications because of their excellent mechanical properties and good durability. In order to provide essential biofunctionalities, surface functionalization is of particular interest and requirement in the development of high-performance metallic implants. Inspired by the functional surface of natural biological systems, many new designs and conceptions have recently emerged to create multifunctional surfaces with great potential for biomedical applications. This review firstly introduces the metallic biomaterials, important surface properties, and then elaborates some strategies on achieving the bioinspired surface functionalization for metallic biomaterials., (Copyright © 2017 Elsevier Ltd. All rights reserved.)