Biopolymer-bioglass-antioxidant composite coatings for protection of 316LVM stainless steel sternal wires against inflammation-induced corrosion

316LVM stainless steel sternal wires (SW) are widely used in cardiothoracic surgery for chest closure. However, in the aggressive environment of the human body, SWs are likely to corrode without a protective coating. This can lead to the release of harmful chromium and nickel in the surrounding tissues or, worse, SW rupture with potentially life-threatening complications, such as heart lacerations. SW degradation is caused by several factors, like chloride attack promoted by the creation of confined areas (e.g., at the chest bone/SW interface), plastic deformation due to the placement of SW around the bone, and tensile stress. Moreover, after implantation, the patients immune system unavoidably triggers an acute inflammation episode during which leukocytes generate reactive oxygen species (ROS), such as H2O2 and radicals (notably via the Fenton reactions), that also contribute to the SW deterioration. BioCoatCorr aims to investigate in-depth in vitro degradation of 316LVM SW in phosphate buffer saline involving simultaneously multiple degradation factors (plastic deformation, H2O2, confined areas). For that purpose, electrochemical measurements (corrosion potential monitoring coupled with impedance spectroscopy) will be carried out at various levels of wire deformation. Furthermore, a novel zein-bioglass-cerium protective coating capable of withstanding the harsh SW operative conditions will be prepared using electrophoretic deposition (EPD). The zein biopolymer has been selected for its ductile properties required for matching the significant SW deformation. The cerium will have the functionality of ROS scavenger, limiting the polymer degradation. The anti-corrosion behaviour and mechanical properties of the coatings will be assessed as a function of the synthesis parameters. The results of BioCoatCorr will contribute to developing the next-generation SW with enhanced durability and thus improve patient life quality postoperatively.