Morphological and Surface Potential Characterization of Protein Nanobiofilm Formation on Magnesium Alloy Oxide: Their Role in Biodegradation

Abstract

The formation of a protein nanobiofilm on the surface of degradable biomaterials such as magnesium (Mg) and its alloys influences metal ion release, cell adhesion/spreading, and biocompatibility. During the early stage of human body implantation, competition and interaction between inorganic species and protein molecules result in a complex film containing Mg oxide and a protein layer. This film affects the electrochemical properties of the metal surface, the protein conformational arrangement, and the electronic properties of the protein/Mg oxide interface. In this study, we discuss the impact of various simulated body fluids, including sodium chloride (NaCl), phosphate-buffered saline (PBS), and Hanks’ solutions on protein adsorption, electrochemical interactions, and electrical surface potential (ESP) distribution at the adsorbed protein/Mg oxide interface. After 10 min of immersion in NaCl, atomic force microscopy (AFM) and scanning Kelvin probe force microscopy (SKPFM) showed a higher surface roughness related to enhanced degradation and lower ESP distribution on a Mg-based alloy than those in other solutions. Furthermore, adding bovine serum albumin (BSA) to all solutions caused a decline in the total surface roughness and ESP magnitude on the Mg alloy surface, particularly in the NaCl electrolyte. Using SKPFM surface analysis, we detected a protein nanobiofilm (∼10–20 nm) with an aggregated and/or fibrillary morphology only on the Mg surface exposed in Hanks’ and PBS solutions; these surfaces had a lower ESP value than the oxide layer.

Albumin Protein Impact on Early-Stage In Vitro Biodegradation of Magnesium Alloy (WE43)

“…Furthermore, C 1s signals between 289 and 290 eV reveal the presence of CO 3 2– on the surface of the samples as a result of the biodegradation processes that produce MgCO 3 and CaCO 3 . As a result, the increased intensity of C 1s peaks in the corrosion product layer of the WE43 exposed to the albumin protein, as well as the presence of N 1s peaks, are associated with protein adsorption/complex formation . To better visualize the proportion of protein adsorption on the WE43’s surface in the two different environments, a comparison of the relative atomic ratio between N (N 1s) and the oxidized carbon C 1s ([N/(C2+C3)]) peaks was evaluated.…”

“…The presence of BSA in Hanks caused a modest decrease in the corrosion resistance of WE43 by diminishing the Ca/P and P intensity signals and, in particular, fostering metal-protein complex formation. Due to the defective and thin protective barrier, and nonhomogeneous distribution of phosphate products, the self-protecting effect of these species against corrosion was attenuated in BSA protein media …”

“…Consequently, the specific electrical conductivity (EC) of adsorbed protein nanofilms on biomedical surfaces can significantly influence subsequent biological events, particularly electrochemical interactions at oxide/protein/electrolyte interfaces . It is known that protein adsorption on biomaterial surfaces is a complex process that involves electrostatic, hydrophobic, van der Waals, and hydrogen-bonding interactions . Protein molecules are capable of instantly adsorbing onto biomaterial surfaces, which can initiate the formation of a biofilm, followed by rearrangement, biodegradation, displacement (Vroman effect), or detachment, leading to the formation of protein-metal complexes/conjugates. , However, these protein-adsorption-related biodegradation mechanisms are complicated in the case of biodegradable or bioactive surfaces, such as Mg and Mg alloys.…”

“…Previous studies , have shown that protein molecules, including albumin, can significantly influence the corrosion processes and biodegradation rate of Mg alloys. The concentration of BSA was observed to influence the biodegradation rate of Mg alloys. , On the other hand, when investigating the action of BSA, it was found to initially inhibit corrosion processes, followed by an acceleration of metal dissolution after prolonged immersion. , Studying the early stage of Mg degradation in simulated body fluids is crucial for understanding its initial response, biocompatibility, corrosion rate, optimization, safety, and eventual clinical use. , However, the specific role of BSA protein in the early-stage (up to 1 h) biodegradation mechanism of magnesium alloys, particularly WE43 alloy, in simple and complex simulated physiological media, such as 154 mM NaCl and Hanks’ solutions, remains largely unexplored. Therefore, this study aims to fill this research gap by elucidating BSA’s impact on the biodegradation behavior of WE43 using advanced techniques.…”

Advances in Bioresorbable Triboelectric Nanogenerators

“…Galvanic coupling arises from dissimilar metal nobilities, resulting in the formation of anodic and cathodic regions characterized by accelerated metal ion release and reduction reactions, respectively. 270 Uniform corrosion entails the comprehensive release of metal ions from the exposed material surface, driven by its high electrochemical activity, while localized corrosion strongly depends on specific chemical heterogeneity and local surface characteristics. 268 For instance, certain metallic biomaterials may exhibit the preferential dissolution of specific components, leading to pitting corrosion or the creation of electrochemically active sites at distinctive features such as edges, kinks, and grain boundaries.…”