Cytotoxicity of the Ga-containing coatings on biodegradable magnesium alloys

Abstract

Biodegradable magnesium alloys, Mg-0·8wt%Ca and Mg-10wt%Gd, have been coated with gallium-containing electrolyte using plasma electrolytic oxidation (PEO). Thus, the PEO procedure is used as a synthesis tool, to create an appropriate content in the layers. This is a first article on the examination of such layers. One part of the gallium-coated samples was additionally sealed with biodegradable poly(L-lactide-co-caprolactone) (PLLC). Gallium content, morphology and thickness of the coatings were evaluated. Special focus was set in relation to the cytotoxicity of the coating, on the two different magnesium alloys and the additional sealing with PLLC. Cytotoxicity was tested using live/dead staining of MC3T3-E1 fibroblasts and by WST-1 assay, cell differentiation by alkaline phosphatase measurement. It could be shown that the gallium-ion concentration in the PEO layer was higher for Mg-10wt%Gd than that of Mg-0·8wt%Ca, which caused a significant difference in the cytotoxic effects toward MC3T3-E1 cells. Still in all cytotoxic tests, Mg-10wt%Gd showed no to low cytotoxic levels, whereby Mg-0·8wt%Ca showed moderate results. Furthermore, it could be proved that an additional PLLC sealing benefits the cell adhesion and thus promotes the cytocompatibility of the coating.

Corrosion Resistance and Cytocompatibility of Magnesium–Calcium Alloys Modified with Zinc- or Gallium-Doped Calcium Phosphate Coatings

“…89 Meanwhile, none to low cytotoxic effect and improvement of corrosion resistance for Mg alloys modified with lower concentrations of gallium (Ga) are available in the literature, although Ga is known as one of the bone resorption inhibitors. 41,90 3.2.2. Cell Viability and Cell−Material Interactions.…”

“…39,40 To overcome this problem, calcium phosphate (CaP) coatings are often applied to the surface of Mg-based orthopedic implants using various methods. 41 Alloying with Ca allows tailoring of the degradation behavior of Mg-based implants for specific in vivo applications, as the degradation rate changes with the Ca content of the alloy. 42,43 Introduction of other elements to Mg− Ca binary alloys also improves the in vivo performance of the material.…”

“…For example, improved mechanical strength and degradation properties were reported for Zn-added Mg−Ca binary alloys, 44 while Ga addition enhanced corrosion resistance, bone-implant bonding, and osteoblast regeneration. 41, 45 Bazhenov and colleagues investigated the mechanical strength and corrosion properties of a Mg−Ga−Zn system and the alloy with a 4% (w/w) Zn and Ga content was proposed as a suitable implant material. 46 The aim of this study was to develop surface-modified Mg− Ca binary alloy-based biodegradable metallic implant materials with a controlled corrosion rate and enhanced biocompatibility.…”

“…Hydrogen gas formed during the corrosion may act as an antioxidant; it has preventative and therapeutic effects on many acute oxidative stress-induced diseases, including neonatal cerebral hypoxia, Parkinson’s disease, ischemia, or reperfusion of the spinal cord, heart, lung, liver, kidney, and intestine. , On the other hand, subcutaneous emphysema caused by H 2 gas may cause discomfort in patients, and lead to further complications such as toxicity due to alkalization of the local environment, tissue necrosis as a result of surgical wound reopening, and defects in the regenerating bone tissue. , To overcome this problem, calcium phosphate (CaP) coatings are often applied to the surface of Mg-based orthopedic implants using various methods . Alloying with Ca allows tailoring of the degradation behavior of Mg-based implants for specific in vivo applications, as the degradation rate changes with the Ca content of the alloy. , Introduction of other elements to Mg–Ca binary alloys also improves the in vivo performance of the material.…”

Editorial

“…The authors demonstrate, for the first time, that cytocompatibility of magnesium-based alloys can be significantly improved when these alloys are treated with a gallium-containing electrolyte through a plasma electrolytic oxidation process. 3 Additionally, enhancement in cell attachment was achieved by the authors for alloys that were dip-coated with a biodegradable PLLC polymer. Modification of magnesiumbased alloys and their surfaces is also needed to slow down the implant material degradation rate.…”