Interfacial Mechanism of Biological Property Enhancement in Irradiated MAO Coatings by HIPIB

Magnesium alloy micro-arc oxidation (MAO) coatings are limited in biomedical applications due to their poor corrosion resistance. High-intensity pulsed ion beam (HIPIB) treatment enhances corrosion resistance as well as biocompatibility, but the underlying mechanisms are not well understood. In this study, CCK-8 assays, flow cytometry, and ALP activity tests were employed to investigate the bioactivity of the MAO coatings, and the surface properties of the coatings were characterized by SEM observation. Compared with pristine coating, the porosity of the MAO coating decreased by 9.44%, calcium content increased by 0.23%, and surface roughness and hydrophobicity increased to 7.57 and 102.11, respectively, with HIPIB irradiation. CCK-8 assays showed that the HIPIB-modified coating significantly improved cell proliferation, with a growth rate increase to 61.29% on Day 3. Flow cytometry analysis revealed accelerated cell cycle progression, especially a faster transition from the G1 to S and G2 phases, indicative of enhanced proliferation. Increased ALP activity further indicated that the irradiated coatings promoted osteogenic differentiation. The formed remelted dense layer with an increase in Ca content and high roughness induced by HIPIB irradiation not only acts as a corrosion barrier but also promotes the adhesion and differentiation of osteoblasts, which is mainly responsible for the enhancement of biological properties.