NIR-induced corrosion regulation strategy for biodegradable Mg-based implants

Currently, biodegradable Mg-based implants used in clinical practice barely degrade after more than ten months of use. To achieve controlled degradation, we prepare a novel surface system on a Mg-Mn-Ag alloy composed of a ceramic layer produced by plasma electrolytic oxidation (PEO) and a polypyrrole (PPy)-loaded poly-caprolactone (PCL) composite coating. The surface system exhibits superior corrosion resistance to prevent premature failure of the Mg alloy. After near-infrared (NIR) irradiation, the photothermal conversion effect of PPy promotes the transformation of PCL from a rubbery state to a viscous state, thereby facilitating the infil-tration of external electrolytes for a dramatically increased degradation rate. As a result, the reduction of icorr and |Z|0.01Hz by 4 orders of magnitude after NIR irradiation could be achieved. Hence, this work provides a new strategy for remotely regulating the degradation rate of Mg-based implants.