What is the impact of plastic deformation on cytocompatibility of biodegradable Zn-Mg alloys?

Research on biodegradable zinc requires thorough in vitro cytotoxicity screening as the developed materials are being proposed for various medical implants, including stents. This study investigates the endothelial cell response to a novel Zn-0.8Mg alloy produced via hydrostatic extrusion (HSE), aiming to showcase the impact of plastic deformation on the cytocompatibility of biodegradable zinc-based materials. In doing so, the MTT test for cell viability studies as well as confocal laser scanning microscopy (CLSM) imaging for cell morphology analysis were used. In addition, a cutting-edge diamond-based quantum sensing technique, i.e., T1 relaxometry, was employed to reveal the nanoscale impact of ions on cells. It was demonstrated that the HSE-produced materials exhibited a 10-fold decrease in grain size, microstructural homogenization, and consequently more uniform degradation compared to hot extruded, coarse-grained materials. Despite these differences, the MTT and CLSM data did not show any drastic discrepancies between the endothelial cell response to any of the investigated materials. However, T1 relaxometry measurements indicated that plastic deformation might influence the cytocompatibility of biodegradable zinc-based materials, as evidenced by significant intracellular free radical production in endothelial cells exposed to ions released from the Zn-0.8Mg HSE alloy surface. Overall, no adverse effects of plastic deformation on the cytocompatibility of zinc-based materials were found as free radical generation may play a beneficial role in endothelial cell function, suggesting a complex interaction between material degradation and cellular response.