Surface Treatment With Cell Culture Medium: A Biomimetic Approach to Enhance the Resistance to Biocorrosion in Mg and Mg-Based Alloys-A Review.

In contemporary orthopedics, the demand for temporary biodegradable bone implants has driven the development of materials capable of supporting bone regeneration while gradually resorbing in the body, thereby eliminating the need for secondary removal surgery. Magnesium (Mg) and its alloys have emerged as promising candidates due to their bioactivity, osteoconductivity, and mechanical properties that closely match those of natural bone. Furthermore, the release of Mg ions during degradation has been shown to stimulate osteoblast activity and enhance bone remodeling. Despite the advantages associated with Mg as a bone implant, there are also constraints on its clinical application. The elevated pH values inherent to the Mg corrosion process may adversely affect biocompatibility, in addition to general concerns about the burst release of H gas that originates from the cathodic reaction of Mg corrosion. To address these challenges, biomimetic surface modifications have emerged as a promising strategy to modulate the degradation behavior of Mg and its alloys. In particular, Dulbecco's Modified Eagle Medium (DMEM) cell culture medium serves as an effective biomimetic environment for forming corrosion-resistant layers on Mg-based implants, maintaining physiological pH and mimicking in vivo degradation behavior by facilitating the formation of a carbonated Ca/Mg-phosphate layer with superior resistance to Cl attack compared to Mg(OH). Immersion in DMEM has been shown to induce the formation of calcium phosphate rich protective layers that mimic the natural bone environment and mitigate the rapid biodegradation of Mg and its alloys. This paper provides a review of recent advancements in DMEM modification of Mg-based alloys, including ex situ and in situ formation of protective layers, and in vitro biocorrosion behavior in cell culture medium. Key findings emphasize that synthetic buffers like Tris/HCl and HEPES accelerate corrosion and hinder calcium phosphate formation, while protein-rich media risk contamination during prolonged use. Additionally, electrostatic interactions in DMEM promote hydroxyapatite crystallization, functionalized intermediate layers enhance calcium phosphate deposition, and fluid dynamics must be carefully controlled to stabilize the protective layer. Despite recent progress, key knowledge gaps remain, including limited understanding of the long-term performance and mechanical stability of biomimetic layers under dynamic physiological conditions, as well as the unclear impact of complex in vivo factors like immune responses and enzymatic activity on their degradation.