Preparation of HT/PLA Coatings on Zn-Mn-Mg Alloy Surface for Biomaterials in Bone Tissue Engineering

Zinc, as a promising biodegradable metal, has received the attention of many researchers in the medical field. However, zinc-based implants release excessive zinc ions when degraded in the human physiological environment, which in turn leads to high cytotoxicity and low osteogenic capacity. This study aims to further enhance the biocompatibility of zinc alloys while improving their osteogenic properties. For this purpose, calciumcontaining phosphate (Ca-P) interlayer and polylactic acid (PLA) composite layers with different sealing degrees are prepared on Zn-Mn-Mg alloys by hydrothermal (HT) and dip-coating methods. Results show that the PLA layer is tightly bonded to the Ca-P intermediate layer, and it can effectively prevent early damage at the bone implantation site of the Ca-P layer on the surface of the zinc alloy. Electrochemical and immersion tests show that the composite layer improves the corrosion resistance of the zinc alloy and that the HT/PLA (12 w/v) coatings show a large Ca-P deposition on the surface, which suggests that the composite layer obtained from the preparation has good bioactivity. The HT/PLA (12 w/v) composite layer is the most cytocompatible and more suitable for the attachment of MC3T3-E1 cells among all tested samples. This superiority is manifested by increased survival of MC3T3-E1 cells, good attachment morphology, and highest spreading density. This study provides a certain reference value for surface modification of zinc-based materials, which is favorable for future application in degradable orthopedic surgery.