Electrodeposition of hydroxyapatite coating on Mg alloy modified with organic acid self-assembled monolayers

Abstract

Calcium phosphate coatings are used in orthopedics due to their excellent bioactivity, which improves the bonding between the metal implant and the bone. The use of self-assembling monolayers of long-chain organic acids can induce calcium phosphate growth. In this article, the self-assembling monolayers of stearic acid and octadecylphosphonic acid formed on the Mg alloy surface were additionally modified with electrodeposited hydroxyapatite coating to increase the bioactivity and biocompatibility of the Mg alloy in a physiological solution. Hydroxyapatite coating was prepared by a two-step reaction: hydrogen phosphate formed by electrodeposition at constant potential was converted into hydroxyapatite coating through an acid–base reaction. The results obtained by voltammetry and electrochemical impedance spectroscopy have shown a beneficial effect of organic acid self-assembling monolayer and especially of organic acid self-assembling monolayer modification by hydroxyapatite electrodeposition on the corrosion properties of Mg alloy in physiological solution. Fourier transform infrared spectroscopy and scanning electron microscopy were used to verify the existence of the organic acid SAM|HAp film on the Mg alloy surface and their morphology.

Potential bioactive coating system for high-performance absorbable magnesium bone implants

“…To improve the adhesion of the layer to the substrate it is possible to apply it after the MAO process which can seal surface porosities and decreases the localized corrosion [ 176 ]. A pretreatment of Mg surface with a long-chain organic acid such as stearic acid was shown to modify the surface and make nucleation sites for CaP deposition by electrodeposition [ 177 ]. Recently, Rahman et al (2021), prepared a bioactive hybrid coating on WE43 Mg alloy that consists of Mg(OH) 2 inner layer by an anodization process, HA middle layer by electrodeposition process, and a silk fibroin outer layer by a spin coating process.…”

Znanstveno-istraživačka djelatnost Zavoda za opću i anorgansku kemiju u razdoblju 2010. – 2020.

“…Barijerna svojstva Mg legure znatno može povećati SAM organske kiseline formiran na površini legure, koji je dodatno modificiran elektrodeponiranom biokeramičkom hidroksiapatitnom prevlakom. 18…”

A polyphenol‐induced hydroxyapatite coating modulates corrosion resistance and biocompatibility of magnesium alloys

“…The introduction of functional groups on the surface of the substrate can facilitate the nucleation of biomimetic hydroxyapatite [15][16][17][18][19]. Ivana et al [20] constructed selfassembling monolayers of stearic acid and octadecyl phosphonic acid on the surface of Mg alloy, and then a hydroxyapatite coating was further formed on its surface through electrodeposition. The obtained coating exhibits good corrosion resistance, greatly improves adhesion to the substrate and can increase the bioactivity and biocompatibility of the Mg alloy in a physiological solution.…”