Natural potential difference induced functional optimization mechanism for Zn-based multimetal bone implants

• Published in: Bioactive materials Vol. 44; pp. 572 - 588
• Main Authors: Xu, Jing, Zhang, Zhenbao, Wang, Jianhui, Qi, Yuhan, Qi, Xiaohong, Liang, Yijie, Li, Manxi, Li, Haixia, Zhao, Yantao, Liu, Zhuangzhuang, Li, Yanfeng
• Format: Journal Article
• Language: English
• Published: China Elsevier B.V 01.02.2025; KeAi Publishing Communications Ltd; KeAi Publishing; KeAi Communications Co., Ltd
• Subjects: 1-Phosphatidylinositol 3-kinase; Additive manufacturing; Advanced materials; AKT protein; Alloys; Biocompatibility; Biodegradable metal; Biodegradation; Biomedical materials; Bone biomaterials; Bone growth; Bone implants; Bone repair; Corrosion; Corrosion potential; Degradation; Differentiation (biology); Functionally gradient materials; Interfacial bonding; Investigations; Mechanical properties; Metals; Morphology; Multi-material additive manufacturing; Optimization; Overdose; Potential difference; Regeneration; Regeneration (physiology); Signal transduction; Skin & tissue grafts; Structural design; Surgical implants; Titanium; Toxicity; Yield stress; Zinc; Zn/Ti; Beijing China; China; Bone repair; Potential difference; Biodegradable metal; Zn/Ti; Multi-material additive manufacturing
• ISSN: 2452-199X; 2097-1192; 2452-199X
• DOI: 10.1016/j.bioactmat.2024.10.030

Zn-based biodegradable metals (BMs) are regarded as revolutionary biomaterials for bone implants. However, their clinical application is limited by insufficient mechanical properties, delayed in vivo degradation, and overdose-induced Zn2+ toxicity. Herein, innovative multi-material additive manufacturing (MMAM) is deployed to construct a Zn/titanium (Ti) hetero-structured composite. The biodegradation and biofunction of Zn exhibited intriguing characteristics in composites. A potential difference of about 300 mV naturally existed between Zn and Ti. This natural potential difference triggered galvanic coupling corrosion, resulting in 2.7 times accelerated degradation of Zn. The excess release of Zn2+ induced by accelerated degradation enhanced the antibacterial function. A voltage signal generated by the natural potential difference also promoted in vitro osteogenic differentiation through activating the PI3K-Akt signaling pathway, and inhibited the toxicity of overdose Zn2+in vivo, significantly improving bone regeneration. Furthermore, MMAM technology allows for the specific region deployment of components. In the future, Ti and Zn could be respectively deployed in the primary and non-load-bearing regions of bone implants by structural designs, thereby achieving a functionally graded application to overcome the insufficient mechanical properties of Zn-based BMs. This work clarifies the functional optimization mechanism for multimetal bone implants, which possibly breaks the application dilemma of Zn-based BMs. [Display omitted] •A novel Zn/Ti multimetal bone implant was successfully fabricated by MMAM technology for the first time.•The natural potential difference between Zn and Ti triggered galvanic coupling corrosion, accelerating the degradation of Zn.•The antibacterial performance was significantly enhanced due to the substantial release of Zn2+.•The natural potential difference between Zn and Ti generated voltage signals, enhancing osteogenic activity.