Wood-inspired metamaterial catalyst for robust and high-throughput water purification.

Continuous industrialization and other human activities have led to severe water quality deterioration by harmful pollutants. Achieving robust and high-throughput water purification is challenging due to the coupling between mechanical strength, mass transportation and catalytic efficiency. Here, a structure-function integrated system is developed by Douglas fir wood-inspired metamaterial catalysts featuring overlapping microlattices with bimodal pores to decouple the mechanical, transport and catalytic performances. The metamaterial catalyst is prepared by metal 3D printing (316 L stainless steel, mainly Fe) and electrochemically decorated with Co to further boost catalytic functionality. Combining the flexibility of 3D printing and theoretical simulation, the metamaterial catalyst demonstrates a wide range of mechanical-transport-catalysis capabilities while a 70% overlap rate has 3X more strength and surface area per unit volume, and 4X normalized reaction kinetics than those of traditional microlattices. This work demonstrates the rational and harmonious integration of structural and functional design in robust and high throughput water purification, and can inspire the development of various flow catalysts, flow batteries, and functional 3D-printed materials.

Corrosion fatigue behavior and anti-fatigue mechanisms of an additively manufactured biodegradable zinc-magnesium gyroid scaffold.

Additively manufactured biodegradable zinc (Zn) alloy scaffolds constitute an important branch in orthopedic implants because of their moderate degradation behavior and bone-mimicking mechanical properties. This work investigated the corrosion fatigue response of a zinc-magnesium (Zn-Mg) alloy gyroid scaffold fabricated via laser-powder-bed-fusion additive manufacturing at the first time. The high-cycle compression-compression fatigue testing of the printed Zn-Mg scaffold was conducted in simulated body fluid, showing its favorable fatigue strength, structural reliability, and anti-fatigue capability. The printed Zn-Mg scaffold obtained a 227% higher fatigue strength than that of the printed Zn scaffold but 17% lower strain accumulation at 106 cycles. The accumulative strain of the Zn-Mg scaffold at its fatigue strength was dominant by fatigue ratcheting, since the fatigue damage strain of the scaffold was approximately zero. The corrosion products (ZnO and Zn(OH)2) were conducive to the inhibition of fatigue ratcheting and fatigue damage. Dislocation pile-up and solid solution phases at the grain boundaries of the Zn-Mg scaffold could retard the spreading of the crack tip and impede excessive grain coarsening, improving its fatigue endurance limit. Notably, the printed Zn-Mg scaffold could dissipate the fatigue energy through moderate grain boundary migration, thus reducing its plastic deformation. These findings illuminated the anti-fatigue mechanisms related to microstructural features and corrosive environments and highlighted the promising prospects of additively manufactured Zn-Mg scaffolds in orthopedic applications. STATEMENT OF SIGNIFICANCE: Additive manufacturing (AM) of biodegradable metals shows unprecedented prospects for bone tissue regeneration medicine. The corrosion fatigue property is one of the key determinants in the performance of AM biodegradable scaffolds. In this study, a Zn-Mg gyroid scaffold was additively manufactured with admirable fatigue endurance limit and anti-fatigue capability. We reported that the corrosion fatigue performance was highly relevant to the microstructural features, validating that the grain boundary engineering strategy improved fatigue strength and inhibited crack penetration. Notably, moderate grain boundary migration could dissipate fatigue energy and reduce plastic deformation. Furthermore, corrosion products were conducive to impeding fatigue ratcheting and fatigue damage, indicating the promising potential of AM Zn-Mg scaffolds in treating load-bearing bone defects.

Anisotropic mechanical and mass-transport performance of Ti6Al4V plate-lattice scaffolds prepared by laser powder bed fusion.

In bone scaffolds, the mechanical performance provides the load-bearing capability, and the mass-transport performance presented as permeability dominates the nutrients/oxygen transportation efficiency. Body-centered-cubic and face-centered-cubic plate lattice scaffolds with mechanical and mass-transport performance close to human bones are proposed in the present study. The regular periodic architecture and plane-stress state of the plate lattice scaffolds not only provide them with advanced mechanical properties but avoid stress concentration that ubiquitously exists in traditional truss lattice scaffolds. By investigating the anisotropic mechanical and mass-transport performance of plate lattice scaffolds, a valid regulation strategy is put forward to modulate their performance without changing the volume fraction and architecture, providing an alternative scheme for biomedical scaffold design. Both computational and experimental results demonstrate that body-centered-cubic and face-centered-cubic plate lattice scaffolds possess appropriate mechanical and mass-transport performance close to human bones. In addition, tuning ranges of the mechanical and mass-transport performance of plate lattice scaffolds for different orientations are up to 40% and 45%, respectively. These findings could provide valuable references for the extensive applications of plate lattice scaffolds in bone tissue engineering. STATEMENT OF SIGNIFICANCE: In bone tissue engineering, scaffolds with low density, high strength, and proper permeability are of constant request. The present study proposes body-centered-cubic and face-centered-cubic plate lattice scaffolds with mechanical and mass-transport performance close to human bones. The deformation mechanisms and mass-transport characteristics of plate lattice scaffolds for different orientations are revealed. In addition, a valid regulation strategy is put forward to modulate the mechanical and mass-transport performance of plate lattice scaffolds without changing their volume fraction and architecture, providing an alternative scheme for biomedical scaffold design. We believe that these findings could provide significant guidance for the simultaneous improvements of advanced scaffold designing.