Bioabsorbable magnesium alloys (Mg) are advantageous in temporary functional implant applications, as they avoid the risks posed by permanent metallic implants. Nevertheless, the over-fast corrosion of Mg alloys under physiological conditions hinders its wider use as medical implants. Here we introduce a convenient one-step process to introduce a cross-linked 3-amino-propyltrimethoxysilane (APTES) silane physical barrier layer on the surface of Mg-Zn-Y-Nd alloys before coating with drug-eluting poly (glycolide-co-lactide) (PLGA) layer loaded with rapamycin.
Surface microstructure was characterized by scanning electron microscope (SEM), Fourier transform infrared spectroscopy (FT-IR), X-ray photoelectron spectroscopy (XPS). Nano-scratch test verifies the adhesion strength of the PLGA pre-treated with APTES is superior to direct PLGA coating. Electrochemical testing combined with long-term immersion results indicate that the APTES coating results in preferable in vitro anti-corrosion behaviour. Cell morphology and proliferation tests demonstrate that APTES pre-treated Mg-Zn-Y-Nd substrate shows markedly preferable effects for both human umbilical vein endothelial cells (EA. hy926) and vascular smooth muscle cells (VSMC). Furthermore, the in vivo test via implanting APTES pre-treated Mg-Zn-Y-Nd stent to porcine coronary arteries for 6 months confirms benign tissue compatibility with the well re-endothelialized vessel with no sign of obvious thrombogenesis and restenosis.
National Basic Research Program of China (Grant No. 2012CB619102); Shenzhen Science and Technology Funding Projects (CXZZ20140730091722497); Shenzhen Special Funds for Development of Strategic Emerging Industries(Project No. JCYJ20130402172)
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