Zn content mediated fibrinogen adsorption on biodegradable Mg-Zn alloys surfaces

The protein adsorption has an immense influence on the biocompatibility of biodegradable Mg alloy. In this work, the effect of Zn content on the fibrinogen (Fg) adsorption behavior in Mg-Zn binary alloy was systematically investigated. Experimental results showed that the Fg adsorption amount increased at first and then decreased with the increase of Zn content. The adsorption mechanism was investigated by molecular dynamic and density functional theory simulations. The simulations results showed that Zn with low content existed in the inner layer of Mg alloys due to the lower system energy, which promoted Fg adsorption and the promotion effect was more obvious with the increase of Zn content. When Zn content increased to a higher concentration, parts of Zn atoms started to precipitate in the surface, and the Fg-surface interaction energy started to increase. Moreover, the Zn sites favored the formation of ordered water molecules layers, which inhibit the stable adsorptions of Fg. The inhibition effects of Fg adsorption was enhanced with the Zn content increase. In short, the simulation results explain the experimental phenomena and reveal the microscopic mechanism. This study would provide a significant guidance on the design of biodegradable Mg-Zn alloys.