A microfluidic system simulating physiological fluid environment for studying the degradation behaviors of magnesium-based materials

Magnesium (Mg) -based materials have excellent potential for applying in biodegradable vascular stents. In recent years, many Mg-based materials are developed for stent preparation. Before application, all these materials need to be screened and optimized, especially the screening of corrosion resistance, which is one of the key indicators for stent material screening. Based on the characteristics of the structure of the stent, we focus on the study of the corrosion and degradation behavior of the micron-scale stent struts in the simulated in vivo environment. The struts are simplified into Mg-based wires, and a microfluidic system is established to provide near physiological conditions. A flow-induced shear stress (FISS) of approximately 0.68 Pa close to the wall shear stress of the human coronary artery is applied to the sample surface relying on the microfluidic system. The degradation behaviors of Mg-based wire samples close to the size of struts are studied simultaneously in parallel under FISS condition using this microfluidic system. The immersion test and in vivo experiments demonstrated the feasibility of this microfluidic system for studies of the degradation behavior of Mg-based materials under simulated physiological conditions. In addition, it was also investigated that the effect of degradation products produced under dynamic conditions on vascular cell behavior. The results show that the degradation rate is significantly accelerated under the effect of FISS in the in vitro study, the degradation rate is obviously higher than that in vivo, and AZ31 has the fastest degradation rate compared with pure magnesium and Mg-Zn-Y-Nd alloys. Taken together, this microfluidic system can be used to evaluate and screen the corrosion resistance of Mg-based materials, providing a basis for the design and optimization of Mg-based cardiovascular stent materials.