Constructing a functional hybrid coating appears to be a promising strategy for addressing the poor corrosion resistance and insufficient endothelialization of Mg-based stents. Nevertheless, the steps for preparing composite coatings are usually complicated and time-consuming. Herein, a novel composite coating, composed of bioactive magnesium thioctic acid (MTA) layer formed by deposition and corrosion-resistant magnesium hydroxide (Mg(OH)₂) layer grown in situ, is simply fabricated on ZE21B alloys via one-step electrodeposition. Scanning electron microscopy (SEM) shows that the electrodeposited coating has a compact and uniform structure. And the high adhesion of the MTA/Mg(OH)₂ hybrid coating is also confirmed by the micro-scratch test. Electrochemical test, scanning kelvin probe (SKP), and hydrogen evolution measurement indicate that the hybrid coating effectively reduces the degradation rate of Mg substrates. Haemocompatibility experiment and cell culture trial detect that the composite coating is of fine biocompatibility. Finally, the preparation mechanism of MTA/Mg(OH)₂ hybrid coatings is discussed and proposed. This coating shows a great potential application for cardiovascular stents.

Protein adsorption preferentially occurs and significantly affects the physicochemical reactions once the biodegradable magnesium alloys as bone replacements have been implanted. To date, interactions mechanisms between Mg implants and proteins remain unclear at a molecular level. Thereby, a combination of molecular dynamic (MD) simulations and experimental exploration is used to investigate the adsorption behavior and conformational change of bovine serum albumin (BSA), a representative protein of blood plasma, upon the surface of micro-arc oxidation (MAO) coated Mg alloy AZ31. The influences of absorbed proteins on the cytocompatibility of MAO coating are evaluated by virtue of cytotoxicity assay. Results indicate that the negatively charged O atoms (BSA) exhibit strong interaction with Mg²⁺ ions of Mg(OH)₂, revealing that BSA molecules are ionically adsorbed on the AZ31 surface. Interestingly, MD simulation reveals that MAO coating demonstrates superior ability to capture BSA molecules during the process of adsorption owing to strong electric attraction between the negatively charged O atoms in BSA molecules with Mg atoms of MgO in MAO coating. Moreover, the α-helix part of absorbed BSA molecules on AZ31 substrate and MAO coating markedly decreases with an increase in β-sheet, β-turn and unordered contents, which is attributed to the reduction in the number of hydrogen bonds in BSA molecules. Furthermore, the adsorbed BSA molecules improve the cytocompatibility of MAO coating since the positively charged -NH₃⁺ group and β-sheet content of absorbed BSA molecules mediate the cell adhesion by interacting with the negatively charged cell membrane.