In Vitro Corrosion and Cytocompatibility of a Microarc Oxidation Coating and Poly(l-lactic acid) Composite Coating on Mg–1Li–1Ca Alloy for Orthopedic Implants

Abstract

Manipulating the degradation rate of biomedical magnesium alloys poses a challenge. The characteristics of a microarc oxidation (MAO), prepared in phytic acid, and poly(L-lactic acid) (PLLA) composite coating, fabricated on a novel Mg-1Li-1Ca alloy, were studied through field emission scanning electron microscopy (FE-SEM), electron probe X-ray microanalysis (EPMA), energy dispersive X-ray spectroscopy (EDS) and X-ray diffraction (XRD). The corrosion behaviors of the samples were evaluated via hydrogen evolution, potentiodynamic polarization and electrochemical impedance spectroscopy in Hanks' solution. The results indicated that the MAO/PLLA composite coatings significantly enhanced the corrosion resistance of the Mg-1Li-1Ca alloy. MTT and ALP assays using MC3T3 osteoblasts indicated that the MAO/PLLA coatings greatly improved the cytocompatibility, and the morphology of the cells cultured on different samples exhibited good adhesion. Hemolysis tests showed that the composite coatings endowed the Mg-1Li-1Ca alloys with a low hemolysis ratio. The increased solution pH resulting from the corrosion of magnesium could be tailored by the degradation of PLLA. The degradation mechanism of the composite coatings was discussed. The MAO/PLLA composite coating may be appropriate for applications on degradable Mg-based orthopedic implants.

In vitro degradation and biocompatibility of Mg-Li-Ca alloys—the influence of Li content

“…Our previous studies [6,10,11,22] and others [23] indicate that Mg-LiCa alloys may be one of the candidate materials. Ca is one of the major elements in bones, the second large amount of cations in human body, and has the potential to further reduce the density of Mg-Li alloys, refine the microstructure and improve the mechanical strength by forming the intermetallic compound Mg 2 Ca [24].…”

“…The detailed process was recorded in our previous study [6,11,28,29]. The samples were immersed in HBSS at 37.0±0.5°C for three weeks.…”

“…Mg alloys are considered as appropriate candidates for biodegradable cardiovascular stents and bone replacement metallic implants due to their excellent biocompatibility and osteoconductivity [1][2][3][4][5][6]. While the existing commercial Mg alloys cannot meet the needs for mechanical properties, corrosion resistance and biocompatibility of the degradable implants [7][8][9].…”

“…Furthermore, our previous investigation [26] discloses that the Mg-1Li-1Ca alloy is non-cytotoxic to osteoblasts, and the cytotoxicity of the Mg-1Li-1Ca alloy is lower than that of pure Mg and AZ31B alloy. The Mg-1Li-1Ca alloy has no impact on osteoblast proliferation and shows good biocompatibility [6]. Unfortunately, little information is available in the literature with regard to the corrosion, mechanical property and biocompatibility of the ternary Mg-Li-Ca alloys [27].…”

In vitro and in vivo studies on as-extruded Mg- 5.25wt.%Zn-0.6wt.%Ca alloy as biodegradable metal

“…Magnesium alloys are promising candidates for temporary implants [5][6][7][8][9]. Magnesium alloys can corrode gradually in physiological environment.…”