Three-dimensional (3D) printing provides a promising way to fabricate biodegradable scaffolds with designer architectures for the regeneration of various tissues. However, the existing 3D-printed scaffolds commonly suffer from weak cell-scaffold interactions and insufficient cell organizations due to the limited resolution of the 3D-printed features. Here, composite scaffolds with mechanically-robust frameworks and aligned nanofibrous architectures are presented and hybrid manufactured by combining techniques of 3D printing, electrospinning, and unidirectional freeze-casting. It was found that the composite scaffolds provided volume-stable environments and enabled directed cellular infiltration for tissue regeneration. In particular, the nanofibrous architectures with aligned micropores served as artificial extracellular matrix materials and improved the attachment, proliferation, and infiltration of cells. The proposed scaffolds can also support the adipogenic maturation of adipose-derived stem cells (ADSCs) in vitro. Moreover, the composite scaffolds were found to guide directed tissue infiltration and promote nearby neovascularization when implanted into a subcutaneous model of rats, and the addition of ADSCs further enhanced their adipogenic potential. The presented hybrid manufacturing strategy might provide a promising way to produce additional topological cues within 3D-printed scaffolds for better tissue regeneration.

Electric eel is an excellent example to harness ion-concentration gradients for sustainable power generation. However, current strategies to create electric-eel-inspired power sources commonly involve manual stacking of multiple salinity-gradient power source units, resulting in low efficiency, unstable contact, and poor flexibility. Here we propose a consecutive multimaterial printing strategy to efficiently fabricate biomimetic ionic hydrogel power sources with a maximum stretchability of 137%. The consecutively-printed ionic hydrogel power source filaments showed seamless bonding interface and can maintain stable voltage outputs for 1000 stretching cycles at 100% strain. With arrayed multi-channel printhead, power sources with a maximum voltage of 208 V can be automatically printed and assembled in parallel within 30 min. The as-printed flexible power source filaments can be woven into a wristband to power a digital wristwatch. The presented strategy provides a tool to efficiently produce electric-eel-inspired ionic hydrogel power sources with great stretchability for various flexible power source applications.

Highlights: 3D printing offers unprecedented on-demand and rapid manufacturing capabilities in space. Space 3D printing has demonstrated potential in applications such as tool manufacturing, biomedicine, electronics repair, food production, and resource utilization. 3D printing of polymers, metals, and cell-laden substances has been achieved in space. Challenges of 3D printing in extreme space environments include microgravity, high levels of vacuum, significant temperature differentials, and the impact of cosmic and solar radiation.