Conductivity Sensor for Real‐time Monitoring of Magnesium Corrosion under Cell Culture Conditions

Due to its ability to biodegrade in an aqueous, chloride-containing environment, magnesium (Mg) metal, pure or as an alloy, has attracted significant interest in biomaterials research for use in biodegradable implants for bone repair and other applications. However, the interactions between Mg metal and surrounding cells and tissues as the metal resorbs need to be studied extensively to ensure adequate biocompatibility for each intended application. Cell death can result from high local concentrations of the soluble resorption products, which include Mg ions (Mg2+), alloying products, increased pH and hydrogen. Because these products are primarily ionic, we tested whether a conductivity sensor could be used to monitor Mg degradation by detecting changes in ionic strength in real time, in three physiologically appropriate fluids (a sodium chloride solution, phosphate buffered saline and a cell culture medium maintained under the standard conditions used for mammalian cell culture). Here we demonstrate that an electrochemical conductivity sensor, in combination with a pH sensor, recorded very different patterns of real-time changes in the ionic environment created by Mg immersion and degradation in the three model electrolyte solutions, over a 48-hour time period.