Mg ZX10 for peripheral nerve regeneration: comparative corrosion studies under simulated biological conditions

MALVESTITI, L; TANO DE LA HOZ M.F.; USACH V; SETTON P; KATUNAR M.R.; CERE S.

Congreso; XII Latin-American Congress of Artificial Organs and Biomaterials; 2023

Introduction and objective: Peripheral neuropathies are neurodegenerative diseases caused by dysfunction of one or more peripheral nerves. Magnesium (Mg)-based alloys emerge as potential biomaterials for the construction of nerve guide conduits. The primary constraint associated with this element is its high corrosion rate in the physiological environment. Moreover, the sterilization process and its impact are frequently overlooked in material research studies, despite its crucial nature. Sterilized and non-sterilized Mg ZX10 alloy were studied. Its degradation was evaluated in SBF (simulated physiological solution) and in DMEM (Dulbecco´s modified Eagle´s medium) high glucose with 10% fetal bovine serum (S) and its cytocompatibility was analyzed.Methodology: The microstructure of the Mg ZX10 alloy (Magnesium Innovation Center, Germany) was analyzed. The hydrophilic character of unsterilized (control) and sterilized (oven at 180º 1h) alloy was determined by measuring the contact angle and their surface energy was calculated. Subsequently, both groups of samples were immersed in SBF (37ºC) and the sterilized samples were immersed in DMEM+S (37ºC and 5% CO2) for 1 and 7 days. The alloy evolution was evaluated using: Raman spectroscopy, FTIR-ATR, electrochemical assays and scanning electron microscopy (SEM). Additionally, bone marrow mononuclear cells from rats were cultured varying concentrations biomaterial extracts, followed by MTT assay.Results and discussion: The Mg ZX10 microstructure revealed a homogeneous grain distribution. The control and sterilized samples exhibited hydrophilic surfaces with surface energy values in agreement with previous reports [1]. Upon immersion in SBF, Raman spectroscopy detected the presence of magnesium oxides-hydroxides, phosphates and carbonates compounds in both groups of samples without significant differences. FTIR spectra of the sterilized alloys, after immersion in DMEM+S, showed the presence of amide and carbon-carbon bonds, magnesium-oxides, as well as phosphates and carbonates groups. These findings suggested the deposition of organic and inorganic compounds on the alloy surface. Electrochemical tests showed a significant reduction in the oxidation process of the sterilized alloy immersed in DMEM+S compared to that observed in SBF. SEM images showed that the alloy, previously immersed in SBF, exhibited degradation cracks. On the contrary, the sterilized alloy surface immersed in DMEM+S was more homogenous with deposit of structures similar to nanoflowers [2]. After 3-day culture, increasing extract concentration resulted in decreased cell viability. However, after 7 days, there were no significant differences in cell viability between the extract-exposed cells and the control group. Similarly, there were no notable differences in cell viability among different extract concentrations.Conclusions: The sterilization process does not significantly change the surface characteristics of Mg ZX10. After alloy immersion in DMEM+S, deposits of organic-inorganic components with nanoflowers morphology were observed. Contrarily, in SBF the Mg alloy typical degradation was evidenced. This underscores the importance of interpreting the findings within the context of the specific analyzed system. Still, these studies could serve as a foundation for potential surface modifications in order to optimize Mg-alloy properties.References[1] Liu X.L. et al., Effect of sterilization process on surface characteristics and biocompatibility of pure Mg and MgCa alloys. Materials Science and Engineering C 33, 4144-4154, 2013.[2] Hossein J. et al., Organic-inorganic hybrid nanoflowers: The known, the unknown, and the future. Organic-inorganic hybrid nanoflowers: The known, the unknown, and the future 309, 102780, 2022.