Abstract
A strategy of suppressing the fast degradation behaviour of Mg-based biomaterials by the introduction of one of Mg degradation products Mg(OH)2 was proposed according to the following degradation mechanism, Mg + 2H2O ⇋ Mg(OH)2 + H2↑. Specifically, Mg(OH)2 submicron particles were mixed into poly (L-lactic acid) (PLLA) to synthesize a composite coating onto hydrofluoric acid-pretreated Mg-Nd-Zn-Zr alloy. The in vitro degradation investigations showed that the addition of Mg(OH)2 particles not only slowed down the corrosion of Mg matrix, but also retarded the formation of gas pockets underneath the polymer coating. Correspondingly, cytocompatibility results exhibited significant improvement of proliferation of endothelial cells, and further insights was gained into the mechanisms how the introduction of Mg(OH)2 particles into PLLA coating affected the magnesium alloy degradation and cytocompatibility. The present study provided a promising surface modification strategy to tailor the degradation behaviour of Mg-based biomaterials.
Highlights
Among the varieties of surface modification techniques[7,8,9,10,11,12,13,14,15,16], polymer coating presents as a facile and effective method for protecting magnesium alloy from rapid corrosion
Compared with Poly(L-lactic acid) (PLLA) coating, the introduction of Mg(OH)[2] particles increased the resistance of the polymer Rf as well as the value of Rct, implying the charge transfer process was impeded and the corrosion reaction occurred at the interface of MgF2/Mg was slower than that of the PLLA-coated substrate
A composite PLLA coating with Mg(OH)[2] particles was prepared on Mg alloy substrate, with the Mg(OH)[2] particles uniformly distributing in the polymer coating
Summary
Among the varieties of surface modification techniques[7,8,9,10,11,12,13,14,15,16], polymer coating presents as a facile and effective method for protecting magnesium alloy from rapid corrosion. An ideal polymer coating for biodegradable magnesium alloy implants is considered to own suitable mechanical properties, excellent biocompatibility and controlled degradation rate, apart from preventing magnesium substrate from too rapid corrosion, prolonging its life expectancy. A composite PLLA coating mixed with Mg(OH)[2] submicron particles was prepared on JDBM covered with a conversion layer generated by the pre-treatment with hydrofluoric acid (noted as HF) to provide short-term protection. To our knowledge, this is the first time reported to prepare a composite coating consisting of PLLA and Mg(OH)[2] on magnesium alloy-based implant materials and to achieve a significant protective effect and good biocompatibility with this coating. The effect on the cytocompatibility of the composite coating was quantitatively evaluated with endothelial cell line model
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