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Biodegradable zinc (Zn) based materials have been regarded as promising candidates for orthopedic applications owing to their suitable biodegradability. However, pure Zn exhibited poor mechanical performance and inadequate biofunctionality, which restricted its biomedical applications. Herein, biodegradable Zn-Mg-Cu alloys were developed to enhance the mechanical strength of the Zn matrix and endow the alloys with antibacterial activity. The effect of Cu addition on corrosion behavior, biocompatibility and antibacterial activity of biodegradable Zn-3Mg-xCu alloys was systematically investigated. In vitro immersion test revealed that Zn-3Mg-1Cu exhibited an increasing corrosion rate of 0.0504 mm y ^−1 . The relative cell availability of MC3T3-E1 cells was over 70% after co-culture with 2-fold diluted extracts of the Zn-3Mg-xCu alloy for 3 d, indicating acceptable cytotoxicity. The Cu addition could enhance the antibacterial activity of the Zn-3Mg matrix, and Zn-3Mg-1Cu alloy exhibited the highest inhibition zone diameter (IZD) values of 10.4 mm and 6.0 mm against S. aureus and E. coli , respectively. Overall, the Zn-3Mg-1Cu could be recognized as a promising biodegradable orthopedic material owing to favorable degradation behavior, satisfying biocompatibility, and substantial antibacterial ability.

BACKGROUND: Biological cage has been widely used in the fields of spinal orthopedics, nanometer materials and bionic biomedicine as the substitutes of new bone repair materials due to its high mechanical properties and biocompatibility. However, its effects remain controversial.OBJECTIVE: To summarize and discuss the current design conception, biomechanical characteristics,degradation properties, basic and clinical research of biological cage, so as to provide basis for clinical application of biological cage.METHODS: CNKI, WanFang and PubMed databases were retrieved with the key words "biological cage,biocompatibility, degradation properties, mechanical properties" in Chinese and English, respectively. The preparation, mechanics, degradation characteristics and experiments of biological cage were summarized.RESULTS AND CONCLUSION: One hundred and thirty-two articles were retrieved and 48 eligible articles were included according to inclusion and exclusion criteria. The combination of biphasic or mutiphase materials has become the mainstream of cage design, and tissue engineering and surface modification have effectively promoted the intervertebral fusion. At present, the main drawbacks are the mechanical instability and aseptic inflammation caused by its own degradability which still needs to be further explored. The biological cage based on polylactic acid and β-tricalcium phosphate can complement each other. This copolymer can simultaneously meet the mechanical properties and biocompatibility during the fusion. What needs attention is that the curvature of cage, place position and matching degree with the upper and lower endplates are important factors affecting the intervertebral bone integration. However, the concrete mechanism of osteointegration remains unclear. The gene expression of the cytokines, the signaling pathway, the effect of the cage on the bone repairing cell proliferation and aseptic cage loosening need further exploration. [ABSTRACT FROM AUTHOR]

Abstract: Biocompatible scaffolds play an important role in modulating tissue growth. A gelatin and sodium alginate scaffold with a unique structure produced by a combination of 3‐D printing, electrospinning, and vacuum freeze‐drying has been developed for tissue engineering. The scaffold is composed of a macrostructure, a honeycomb microporous surface morphology, and nanofibers. This structure meets the design criteria for an ideal tissue engineering scaffold. The scaffold degrades and has low cytotoxicity. The biocompatibility of the scaffold is improved by the favorable cell–matrix interaction; cells attach to the scaffold well and secrete large amounts of extracellular matrix in vitro. Rats with the scaffold implanted survived without signs of complications and the host cells infiltrated the interior of the scaffold. After 2 months in vivo, the scaffold was vascularized and contained collagen fibers. This multiscale regeneration scaffold may be suitable for tissue engineering because of its unique structure, degradation, mechanical properties, and lower cytotoxicity, which support cell infiltration and growth, and promote vascularization and generation of granulation tissue in vivo. © 2017 Wiley Periodicals, Inc. J Biomed Mater Res Part B: Appl Biomater, 106B: 1218–1225, 2018. [ABSTRACT FROM AUTHOR]

Zn and Zn-based alloys as biodegradable material have drawn more and more attention in recent years due to their good mechanical properties, lower degradation rate than Mg and acceptable biocompatibility. However, too low degradation rate is a challenge for future application of Zn-based alloys. In this study, Zn-3Cu-xFe (x = 0, 0.5 and 1 wt%) alloys were proposed as candidate biodegradable materials. The microstructure, mechanical and in vitro biodegradable properties were investigated systematically. The Zn-3Cu alloy was composed of Zn matrix and CuZn 5 phase, while the FeZn 13 phase was newly formed with the addition of Fe. Due to the micro-galvanic effect produced by FeZn 13 as a cathodic phase to the Zn matrix, in vitro degradation rate in simulated body fluid solution (SBF) was greatly increased by about 52.1%, from 45.3 ± 8.22 for Zn-3Cu alloy to 68.9 ± 7.34 μm/year for Zn-3Cu-1Fe alloy. Although the mechanical properties were decreased slightly due to the introduction of hard and brittle FeZn 13 secondary phase to the Zn matrix, Zn-3Cu-0.5Fe alloy still exhibits good combined mechanical properties and the YS, UTS and elongation are 232 MPa, 284 MPa and 33%, respectively. Taken together, the mechanical properties and in vitro degradation behavior of the Zn-3Cu-xFe alloys are more suitable than Zn-3Cu alloy as candidate biodegradable materials. [ABSTRACT FROM AUTHOR]