Abstract
Magnesium alloy has become a research hotspot of the degradable vascular stent materials due to its biodegradability and excellent mechanical properties. However, its rapid degradation rate after implantation and the limited biocompatibility restrict its application in clinic. Constructing a multifunctional bioactive polymer coating on the magnesium alloys represents one of the popular and effective approaches to simultaneously improve the corrosion resistance and biocompatibility. In the present study, the copolymer of 6-arm polyethylene glycol and heparin (PEG-Hep) was successfully synthesized and then immobilized on the surface of chitosan (Chi)-modified magnesium alloy surface through electrostatic interaction to improve the corrosion resistance and biocompatibility. The results of attenuated total reflection Fourier transform infrared spectroscopy (ATR-FTIR), X-ray photoelectron spectroscopy (XPS) and scanning electron microscopy showed that a dense and compact coating was created on the magnesium alloy surface. The coating displayed excellent hydrophilicity. At the same time, the as-prepared coating can significantly not only improve the corrosion potential, reduce the corrosion current and the pH changes of the immersion solution, but also keep a relatively intact surface morphology after immersing in simulated body fluid solution for 14 days, demonstrating that the coating can significantly improve the corrosion resistance of the magnesium alloy. Moreover, the magnesium alloy with PEG-Hep coating exhibited excellent hemocompatibility according to the results of the hemolysis rate and platelet adhesion and activation. In addition, the modified magnesium alloy had a good ability to promote the endothelial cell adhesion and proliferation. Therefore, the PEG-Hep multifunctional coating can be applied in the surface modification of the biodegradable magnesium alloy stent to simultaneously improve the corrosion resistance and biocompatibility.
Highlights
Vascular disease caused by the cardiovascular stenosis has become one of the highest incidences and mortality rates in the world (Lv et al, 2017; He et al, 2019)
The chemical structure of the synthesized polyethylene glycol and heparin (PEG-Hep) was characterized by ATR-FTIR and hydrogen nuclear magnetic resonance spectroscopy (1H-NMR)
In 1H-NMR spectra, the integral intensity ratio from low field to high field is 2:3, combined with the results of ATR-FTIR, it can be known that the substance has the chemical structure of CH2-CH3, and the OH peak appeared at 3.42 ppm
Summary
Vascular disease caused by the cardiovascular stenosis has become one of the highest incidences and mortality rates in the world (Lv et al, 2017; He et al, 2019). The stent insertion has significantly reduced the mortality rate (Sigwart et al, 1987; Qi et al, 2013), the inferior biocompatibility of the current non-biodegradable stent and the complications of the late thrombosis and the delayed endothelium healing caused by the released drug from the polymer coating on stent often lead to the implantation failure (Torii et al, 2020). The degradation products of the polymer stents often lead to inflammation, resulting in the occurrence of complications such as late thrombosis and delayed endothelial healing and leading to in-stent restenosis. The biodegradable metal stents have received more and more attention Due to it good mechanical and biodegradable properties, the magnesium alloy has become the research hotspot of the biodegradable cardiovascular stents (Zhang et al, 2021a; Yang et al, 2021). The rapid degradation in vivo and the limited biocompatibility are still great challenges for its clinical application
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