Interfacial Adsorption Mechanisms of Arginine, Glutamic Acid, Aspartic Acid, and Valine on Magnesium and Magnesium Alloy Surfaces: A First-Principles Investigation

Elucidating the interfacial interaction mechanisms between biomolecules and metal surfaces is crucial for designing functionalized biomedical materials. This study employs first-principles calculations based on density functional theory (DFT) to investigate the adsorption behaviors of arginine (Arg), glutamic acid (Glu), aspartic acid (Asp), and valine (Val) on magnesium (Mg) and Mg alloy surfaces. The adsorption behaviors of four kinds of amino acids on Mg and Mg alloy surfaces were analyzed through optimized adsorption configurations, adsorption energies (Eads), bond lengths, projected densities of states (PDOSs), and differential charge densities. The calculated results of Eads followed the order of Arg > Glu > Asp > Val, driven by functional group spatial configurations and electron transfer efficiency. Alloying elements facilitated charge redistribution on the Mg and Mg alloy surfaces, enhancing the interaction between amino acids and the alloy surfaces. Notably, the guanidino group of Arg exhibited exceptional adsorption stability and multi-dentate bonding, increasing electron donation to the Mg(0001) surface, achieving the highest Eads (−1.67 eV). This work provides insights into the structure–activity relationships between amino acids and Mg and Mg alloy surfaces, offering a foundation for designing biomolecule-derived functional coatings and strategies for improving the biocompatibility of Mg and Mg alloy implants.