1. The technical principle is the control of microstructure in relation to biological function.
Metal 3D printing creates detailed 3D structures by melting metal powder one layer at a time with either electron beam melting (EBM) or selective laser melting (SLM) using a powerful beam. Its main benefits stem from:
Using CAD software to build gradient pores (pore size range of 200–800 μ μm, porosity of 60–85%) precisely imitating natural extracellular matrix;
Micro-nano-level rough surface (Ra 1.6 μm) is built by interacting with laser and powder to improve cell adhesion;
Multi-material composite: Using a titanium alloy core with a bioceramic coating in the same structure will create better strength and biological performance.
2. Material innovation: groundbreaking in functionalization and biocompatibility.
While conventional titanium alloy (Ti6Al4V) has excellent corrosion resistance, its 110 GPa elastic modulus is far higher than that of soft tissues (like skin 50 kPa and muscle 100 kPa). A new generation of material systems is transcending this bottleneck:
Ti Ta (75 GPa) and Ti Nb (45 GPa) control lattice distortion by means of tantalum/niobium elements, thereby lowering stiffness in the soft tissue matching range.
When the repair is complete, the temporary supports gradually absorb the magnesium alloy (which degrades at a rate of 0.5–2 mm/year) and zinc alloy (which has antibacterial properties).
Intelligent materials: Under the action of body temperature and dynamically adapting to the tissue healing process, shape memory alloys (like NiTi) regain their preset shape.
From Imitation to Functional Bionics: Structural Design
Metal scaffold design now transcends anatomical form reproduction and moves into the domain of functional biomimetics:
Angiogenesis channel: Design spiral microchannels (300–500 μm wide) to help endothelial cells move in a specific direction and form blood vessel networks.
Making tiny grooves on the scaffold's surface helps to release growth factors like BMP-2 in a controlled way; the design has different levels, from large pores that help cells move in to nanofibers that guide how cells develop.
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