Controlling the biodegradation rate of magnesium using biomimetic apatite coating

Abstract

Magnesium is light, biocompatible and has similar mechanical properties to natural bone, so it has the potential to be used as a biodegradable material for orthopedic applications. However, pure magnesium severely corrodes in a physiological environment, which may result in fracture prior to substantial tissue healing. Hydroxyapatite (HA) is the main composition of natural bone. It has excellent bioactivity and osteoconductivity. In this study, HA coating with two different thicknesses was applied onto the surface of pure magnesium substrates using a biomimetic technique. The corrosion rate of the surface-treated substrates was tested. It was found that both types of coatings substantially slowed down the corrosion of the substrate, and the dual coating was more effective than the single coating in hindering the degradation of the substrate. Thus, the corrosion rate of magnesium implants can be closely tailored by adjusting apatite coating thickness and thereby monitoring the release of magnesium ions into the body.

Microstructure of hydroxyapatite- and octacalcium phosphate-coatings formed on magnesium by a hydrothermal treatment at various pH values

“…HAp coatings have been formed on pure magnesium or magnesium-based alloys by ion beam assisted deposition [11], electrodeposition [12,13] and biomimetic deposition [14]. Although the microstructure of the coatings is important for the corrosion resistance, there has been no systematic report on the microstructure of the coatings formed on magnesium or magnesium-based alloy substrates using transmission electron microscopy (TEM) and high resolution (HR) TEM.…”

Control of magnesium corrosion and biocompatibility with biomimetic coatings

“…Calcium phosphate coatings have been deposited on Mg surfaces, for instance, by ion-beam-assisted deposition 5 or various types of electrochemical and chemical treatments. [6][7][8][9][10][11][12][13] In each case, these coatings lead to a reduced corrosion rate but the crystal structure, chemical composition, and morphology of the coatings, and hence, also the measured degradation rates varied greatly. Of particular interest are Ca-P coatings that spontaneously form on Mg and Mg alloys on exposure to simulated biofluids.…”

Corrosion Behavior of Magnesium with Hydroxyapatite Coatings Formed by Hydrothermal Treatment

“…Surface modification is one of the methods to improve the corrosion resistance. [9][10][11][12][13][14][15][16][17][18][19] Especially, coatings with hydroxyapatite (HAp) and its related calcium phosphate compounds attract attention [11][12][13][14][15][16][17][18][19] because HAp is an essential element of bone and the calcium phosphate compounds precipitated from simulated body fluids improved the corrosion resistance of magnesium. 9,[20][21][22] A single-step process using aqueous solutions consisting of non-toxic compounds is desirable for the formation of HAp coating from the viewpoint of biocompatibility, production cost and environmental load.…”

“…Biomimetic process using a concentrated simulated body fluid was employed; however the crystallinity of HAp precipitated was relatively low. 14) To promote the HAp formation, two-step processes with electrodeposition or ion beam deposition methods have been employed. [11][12][13]18) In the two-step processes, either a pre-treatment or a post treatment is necessary.…”