Biodegradable phosphorus-modified Mg2Ge/Mg-Cu composite with good angiogenic, osteogenic, and antibacterial functionalities for bone-fixation applications

• Hot-extruded Mg-10Ge-2Cu-0.5P (HE MGCP) was prepared by P alloying and hot extrusion. • HE MGCP showed significantly improved corrosion resistance than HE Mg-10Ge-2Cu (MGC). • HE MGCP showed enhanced mechanical and biotribological capability in DMEM than HE MGC. • MGCP showed good cytocompatibility, angiogenic, osteogenic and antibacterial ability. • MGCP showed good in vivo antibacterial and antiinflammatory capability in a rat model. Magnesium (Mg)-based composites are expected to be useful for biodegradable bone-implant materials due to their degradability, similar elastic modulus to that of bone, and biofunctionalities. However, their rapid degradation, poor biotribology performance, and lack of vascularization and antibacterial activity are not conducive to bone-fixation applications. In this study, an in situ Mg 2 Ge/Mg-Cu-P composite with a nominal composition of Mg-10Ge-2Cu-0.5P (denoted MGCP) was prepared via phosphorus (P)-modified casting followed by hot extrusion for biodegradable bone-fixation applications. For comparison, an in situ Mg 2 Ge/Mg-Cu composite (Mg-10Ge-2Cu, denoted MGC) was prepared under the same conditions without P-modification. The hot-extruded (HE) MGCP sample showed significantly improved corrosion resistance with corrosion rates of 2.2 mm/y and 2.51 mm/y as measured by potentiodynamic-polarization and hydrogen-release testing in Dulbecco’s Modified Eagle Medium supplemented with fetal bovine serum (denoted DMEM). The HE MGCP also exhibited notably enhanced mechanical properties and biotribological resistance in DMEM, with an σ UTS of ∼304.2 MPa, σ TYS of ∼202.5 MPa, elongation of ∼12.3%, σ UCS of 769.0 MPa, σ CYS of 208.0 MPa, and Brinell hardness of 105.3 HB, along with smaller σ TYS and σ CYS decreases after 3 d of immersion in Hanks’ solution. In comparison to pure titanium and Mg, the HE MGCP demonstrated much greater cytocompatibility, angiogenic capacity, and osteogenic differentiation and mineralization capability. Furthermore, the HE MGCP displayed markedly higher in vitro antibacterial activity, in vivo antibacterial and anti-inflammatory ability, and good biosafety in a rat subcutaneous-implantation model compared to pure titanium and Mg, indicating significant potential for biodegradable bone-fixation applications.