Insight into synergetic effects of serum albumin and glucose on the biodegradation behavior of WE43 alloy in simulated body fluid

Abstract

The biodegradation rate of Mg alloy medical devices, such as screws and plates for temporary bone fracture fixation or coronary angioplasty stents, is an increasingly important area of study. In vitro models of the corrosion behavior of these devices use revised simulated body fluid (m-SBF) based on a healthy individual’s blood chemistry. Therefore, model outputs have limited application to patients with altered blood plasma glucose or protein concentrations. This work studies the biodegradation behavior of the Mg alloy, WE43, in m-SBF modified with varying concentrations of glucose and bovine serum albumin (BSA) to 1) mimic a range of disease states and 2) determine the contributions of each biomolecule to corrosion. Measurements include the Mg ion release rate, electrolyte pH, the extent of hydrogen evolution (as a proxy for corrosion rate), surface morphology, and corrosion product composition and effects. BSA (0.1 g L–1) suppresses the rate of hydrogen evolution (about 30%) after 24 h and—to a lesser degree—Mg2+ release in both the presence and absence of glucose. This effect gets more pronounced with time, possibly due to BSA adsorption on the Mg surface. Electrochemical studies confirm that adding glucose (2 g L–1) to the solution containing BSA (0.1 g L–1) caused a decrease in corrosion resistance (by around 40%), and concomitant increase in the hydrogen evolution rate (from 10.32-11.04 mg cm–2 d–1) to levels far beyond the tolerance limits of live tissues.

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

“…The hydrogen evolution rate (HER) serves as a proxy for the corrosion rate as both occur at the same rate. , The HER (Figure b) was consistently fastest in NaCl and lowest in Hanks during the initial 6 h of immersion. After 6 h, the HER rate decreases, suggesting the absence of a fresh surface, likely due to the formation of an adsorption layer alongside a complex corrosion product.…”

“…The Zr-rich phases mostly form at the boundary between the LSP and matrix, and they are only sparsely distributed in α-Mg that are consistent with the reported literature. 15,16,41 As can be seen in the EDXS maps, Y is primarily precipitated in Zr-rich phases and is more evenly distributed around the LSPs than in their bulk region. In a further analysis using AFM/SKPFM, detailed information about the topography and surface potential of different regions in the sample, namely, the α-Mg, LSP, and Zrrich regions, was obtained.…”

“…16 In contrast, the amplitude of the current noise increases slightly in Hanks containing BSA compared to Hanks without BSA due to the formation of an imperfect protective film and the heterogeneous distribution of phosphate and calcium phosphate products. 15,16,48 Figure 3 shows the extracted PSD analysis of the EPN and ECN signals in different physiological solutions. The corresponding slope of each PSD curve is known as the spectral power constant, which is related to the fractional Gaussian noise process and represents the properties of selfsimilarity and persistent stationary processes.…”

“…can reduce or accelerate the rate of deterioration of Mg alloys 2,13,14 depending on a variety of factors that include ion type, protein concentration, alloy microstructure, alloy chemical composition, and exposure time. 15 Depending on their molecular structure, 2 adsorbed proteins, either as single molecules or as nanofilms (e.g., mono-or multilayer), are frequently considered to be electrically conductive soft matter. 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.…”

Effect of unsoluble corrosion products of WE43 alloys in vitro on macrophages

“…As the ionization reaction of HCO 3 − is greater in an alkaline environment than the hydrolysis reaction, the dissolution of CO 2 and the presence of HCO 3 − can act as a buffer for the alkaline environment. This produces MgCO 3 29 with CO 2 , or MgPO 4, and MgSO 4 28,30,31 with phosphate or sulfate in Dulbecco's Modification of Eagle's Medium (DMEM). In this study, culture medium was used as the corrosion liquid since culture medium is closer to the internal environment due to the different components in PBS, NaCl, and Hanks' solutions and the different degradation products.…”