Preparation and investigation of Zn foil/poly(lactic acid) composite films for guiding bone regeneration

We prepared Zn/Poly(lactic acid) (PLA) composite films for guiding bone regeneration. The surface of Zn foil was modified by micro-arc oxidation, and the composite films with a sandwich structure were prepared using hot pressing method. The morphology, roughness, porosity, and pore size of Zn foil were investigated with the help of laser microscope and SEM. As a result, the rough and porous surface with the S_a value of 2.764±0.071 μm and porosity of 12.5±3.2 % provided a favorable structural basis for subsequent combination between Zn foil and PLA. While the value of S_a for the MAO-Zn/PLA40 composite film was 4.510±0.080 μm. The main component of the oxide layer was ZnO according to the XRD and XPS results. The tensile strength of MAO-Zn/PLA40 composite film increased by 17.7±0.6 % compared with that of Zn/PLA40 composite film. The interface energy decreased from −7.074 kcal/mol for Zn/PLA to −1433.430 kcal/mol for ZnO/PLA and the total energy level of ZnO/PLA composites shifted towards lower direction according to the density of state results. These results illustrated the enhanced interfacial bonding effect between the micro-arc oxide layer and PLA based on mechanical interlocking and electrostatic attraction. Additionally, micro-arc oxidation accelerated the degradation of Zn foil from initial 0.383±0.029 mm/year to 1.245±0.208 mm/year according to the electrochemical performances. This investigation provided an experimental basis and theoretical guidance for regulating the mechanical properties and degradation rate of this kind of membrane.