Background electrolytes based on natural polymer hydrogels for in vitro electrochemical testing of medical magnesium alloys

Magnesium and its alloys, as typical biodegradable metallic materials for medical applications, are successfully used in bone fixation devices, dental implants, and cardiovascular stents due to their high biocompatibility and controllable degradation characteristics. Accurate quantification of magnesium alloy degradation rates is paramount for establishing their optimal clinical dosage. Excessive implantation risks prolong implant persistence, concomitantly elevating the potential for localized inflammatory reactions. Conversely, insufficient dosage may significantly diminish therapeutic efficacy. Consequently, robust quantitative characterization of magnesium alloy degradation kinetics within the human physiological environment is indispensable for successful clinical translation. Currently, in vitro and in vivo methods are employed to assess their degradation, with in vitro electrochemical testing being the most common quantitative analysis. However, the simulated biological fluids used in modern in vitro systems fail to replicate the complex solid–liquid phase microenvironment of the human body, leading to significant discrepancies between laboratory data and actual in vivo degradation processes.

Given that natural polymer hydrogels derived from autochthonous plant sources exhibit microstructures and chemical compositions similar to human tissues, agar, pectin, and chitosan were selected as alternative approaches for evaluating the corrosion resistance of medical magnesium alloys. Conducted contact corrosion experiments and electrochemical studies demonstrated that the morphology of corrosion products and the degradation kinetics of magnesium alloys in gel electrolytes show significantly higher correlation with in vivo experimental data from mice compared to results obtained in traditional liquid media.

Moreover, due to the tunable properties of gel-based materials, it is possible to design electrolytes tailored to individual patient characteristics and implant localization by modifying the gel's structure and composition. This opens prospects for developing more accurate methods to assess biomaterial degradation under conditions that closely mimic physiological environments.