The application of medical magnesium (Mg) alloys in implantable medical devices is promising due to the similar modulus of elasticity and biodegradability to human bone, which facilitates osseointegration. However, rapid degradation and loss of mechanical strength remain critical issues. To tackle these challenges, in this study, liquid metal gallium (Ga), which possesses non-toxicity, excellent biocompatibility, moderate chemical reactivity, and superior alloying capability, was used to develop a novel Mg alloy coating that can simultaneously enhance mechanical strength, reduce the degradation rate, and provide antibacterial and osteogenic properties. A unique, simplified coating process applied liquid Ga to the surface of ZK60 Mg alloy, and coatings of varying thicknesses were successfully fabricated. The phase composition of the Mg-Ga alloy layers was identified mainly consisting of Ga₅Mg₂ and Ga₂Mg. Vitro corrosion tests demonstrated that surface alloying of Ga with ZK60 effectively suppressed the degradation rate of the Mg alloy. Prolonged Mg-Ga alloying time improved human bone marrow mesenchymal stem cells (hBMSCs) adhesion, spreading, proliferation, and differentiation. The Mg-Ga alloy layer positively affected the early differentiation of osteoblasts and extracellular matrix mineralization, upregulating the expression of osteogenic-related genes and inhibiting osteoclast activity. Additionally, the Mg-Ga alloy exhibited excellent antibacterial properties through a combined effect of ion release and the formation of an alkaline environment. In short, the Ga-coated ZK60 Mg alloy demonstrated superior corrosion resistance, structural stability, cellular compatibility, osteogenic performance, and antibacterial capability, providing strong support for applying Mg alloys in medical implants.

Magnesium (Mg) alloys with biodegradability and excellent mechanical properties are in high demand for applications in guided bone regeneration (GBR). However, the clinical application of Mg alloys is hindered by infection risks and limited osteogenesis. Herein, a structure-functional integrated Mg-Ca/Mg-Cu bilayer membrane was rolled at 150 ℃ through various single-pass reductions by using online heating rolling. The Mg-Cu layer was specifically engineered to exhibit antibacterial properties tailored for gingival tissue, while the Mg-Ca layer was designed to support bone regeneration within the defect cavity. The bilayer membrane demonstrated a flexural yield strength of 421.0 MPa and a modulus of 58.6 GPa, indicating exceptional deformation resistance. Furthermore, it maintained notable structural stability by retaining 86.4% of its volume after 21 days in Hanks’ solution. In vitro results revealed that the bilayer membrane exhibited favorable biocompatibility and promoted osteogenesis via the synergetic effect of released Mg²⁺ and Ca²⁺ ions. The rapid release of Cu²⁺ ions and the creation of an alkaline environment further improved antibacterial properties, potentially preventing postoperative infections. Additionally, in an in vivo rat calvarial defect model, the membrane demonstrated its capability to stimulate new bone formation. In summary, the Mg-Ca/Mg-Cu bilayer membrane exhibited outstanding mechanical stability, favorable corrosion rates, extraordinary osteogenic and antibacterial activity simultaneously. Consequently, it holds promise as a robust barrier membrane in GBR applications.

In bone tissue engineering, scaffolds with excellent mechanical and bioactive properties play prominent roles in space maintaining and bone regeneration, attracting increasingly interests in clinical practice. In this study, strontium-incorporated β-tricalcium phosphate (β-TCP), named Sr-TCP, bioceramic triply periodic minimal surface (TPMS) structured scaffolds were successfully fabricated by digital light processing (DLP)-based 3D printing technique, achieving high porosity, enhanced strength, and excellent bioactivity. The Sr-TCP scaffolds were first characterized by element distribution, macrostructure and microstructure, and mechanical properties. Notably, the compressive strength of the scaffolds reached 1.44 MPa with porosity of 80%, bringing a great mechanical breakthrough to porous scaffolds. Furthermore, the Sr-TCP scaffolds also facilitated osteogenic differentiation of mouse osteoblastic cell line (MC3T3-E1) cells in both gene and protein aspects, verified by alkaline phosphatase (ALP) activity and polymerase chain reaction (PCR) assays. Overall, the 3D-printed Sr-TCP bioceramic TPMS structured scaffolds obtained high porosity, boosted strength, and superior bioactivity at the same time, serving as a promising approach for bone regeneration.