Due to its excellent bone-like mechanical properties and non-toxicity, magnesium (Mg) and its alloys have attracted great interest as biomaterials for orthopaedic applications. However, their fast degradation rate in physiological environments leads to an acute inflammatory response, restricting their use as biodegradable metallic implants. Endowing Mg-based biomaterials with immunomodulatory properties can help trigger a desired immune response capable of supporting a favorable healing process. In this study, electrospun poly(ε-caprolactone) (PCL) fibers loaded with coumarin (CM) and/or zinc oxide nanoparticles (ZnO) were used to coat the commercial AZ31 Mg alloy as single and combined formulas, and their effects on the macrophage inflammatory response and osteoclastogenic process were investigated by indirect contact studies. Likewise, the capacity of the analyzed samples to generate reactive oxygen species (ROS) has been investigated. The data obtained by attenuated total reflection Fourier-transform infrared (FTIR-ATR) and X-ray photoelectron spectroscopy (XPS) analyses indicate that AZ31 alloy was perfectly coated with the PCL fibers loaded with CM and ZnO, which had an important influence on tuning the release of the active ingredient. Furthermore, in terms of degradation in phosphate-buffered saline (PBS) solution, the PCL-ZnO- and secondary PCL-CM-ZnO-coated samples exhibited the best corrosion behaviour. The in vitro results showed the PCL-CM-ZnO and, to a lower extent, PCL-ZnO coated sample exhibited the best behaviour in terms of inflammatory response and receptor activator of nuclear factor kappa-B ligand (RANKL)-mediated differentiation of RAW 264.7 macrophages into osteoclasts. Altogether, the results obtained suggest that the coating of Mg alloys with fibrous PCL containing CM and/or ZnO can constitute a feasible strategy for biomedical applications.
Magnesium alloys are used for degradable orthopaedic and cardiovascular implants due to their favourable mechanical and biological properties, degradation ability in physiological environment and stimulatory effect on the new bone formation. The research challenges are related to the increase of biological and mechanical compatibility. For the present study, a magnesium based alloy design was conducted to the following chemical composition: Mg−2.7Zn−1Ca−0.6Zr (wt.%). A complex thermomechanical processing route was applied: a plastic deformation by extrusion at various temperatures and deformation degrees (400 °C–480 °C, ϵ = 20 %–40 %), followed by various final heat treatments at 200 °C–400 °C for 10 min–60 min. Further, the influence of processing parameters upon the structure, mechanical properties and biological response was studied. Processed specimens were characterized by scanning electron microscopy (secondary electron imaging and energy dispersive spectroscopy) and mechanically by tensile tests. The most representative results were obtained for the samples extruded at 450 °C/ϵ = 20 %, followed by a final heat treatment at 350 °C/15 min, air cooling. Further, for samples which revealed promising results, in‐vitro testing was developed. Biocompatibility testing of the Mg−2.7Zn−1Ca−0.6Zr (wt.%) alloy was realized by indirect contact studies using the Vero (ATCC® CCL‐81™, American Type Culture Collection) cell line. Cells morphologies, cell viability and proliferation were evaluated.
With the rapid advancement of medical technology, it is crucial that a considerable body of biomaterials are taken into consideration and tested for the purpose of bone implant fabrication. Over the last decades degradable metallic materials have attracted increasing interest in the field of hard tissue engineering due to their ability to degrade once they have fulfilled their function, without causing side effects that could potentially be harmful for the human body. In this context, Mg-based biomaterials gained special attention due to their bone-like mechanical properties, good biocompatibility and osteoconductive properties. However, their use in biomedical applications is limited due to their rapid corrosion in physiological environments. Therefore, it is important to reduce the degradation process of these biomaterials for safe biomedical applications. Two main strategies that could potentially lead to a lower corrosion rate are represented by alloying and surface treatment. This review provides a summary of the recent specialized literature concerning Mg-based biomaterials with a special focus on the recent in vitro and in vivo studies regarding Mg-based bone implants.
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