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Peripheral nerve injuries (PNIs) have a significant impact on the quality of life for patients suffering from trauma or disease. In injuries with critical nerve gaps, PN regeneration requires tissue scaffolds with appropriate physiological properties that promote cell growth and functions. Hydrogel scaffolds represent a promising platform for engineering soft tissue constructs that meet key physiological requirements. Nonetheless, ongoing innovation remains essential, as current designs continue to fall short of replicating the functional performance of autografts in bridging critical-sized nerve defects. In this study, gelatin methacrylate (gelMA)-based hydrogels are evaluated to fully characterize their pore structure, compressive stiffness, viscoelasticity, and 3D bioprintability. Hyaluronic acid (HA) and single-walled carbon nanotubes (SWCNTs) are explored as gelMA additives to modify viscoelastic and electrically conductive properties, respectively. Finally, Schwann cell (SC) and human umbilical vein endothelial cell (HUVEC) growth and functions are quantified to assess the biocompatibility of the hydrogel composites as materials for nerve scaffold fabrication. It was found that the microstructure and mechanical properties of gelMA-based hydrogels can be precisely controlled by modifying the concentrations of each component. The addition of HA led to altered viscoelastic properties of the cured structures and SWCNTs increased electrical conductivity, with both additives maintaining cytocompatibility while influencing the protein expression of both SCs and HUVECs. These composite hydrogels have potential in PNI regeneration applications. 

Effectively translating the promising properties of boron nitride nanotubes (BNNTs) into macroscopic assemblies has vast potential for applications, such as thermal management materials and protective fabrics against hazardous environment. We spun fibers from aqueous dispersions of BNNTs in polyvinyl alcohol (PVA) solutions by a wet spinning method. Our results demonstrate that BNNTs/PVA fibers exhibit enhanced mechanical properties, which are affected by the nanotube and PVA concentrations, and the coagulation solvent utilized. Compared to the neat PVA fibers, we obtained roughly 4.3-, 12.7-, and 1.5-fold increases in the tensile strength, Young's modulus, and toughness, respectively, for the highest performing BNNTs/PVA fibers produced from dispersions containing as low as 0.1 mass% of nanotube concentration. Among the coagulation solvents tested, we found that solvents with higher polarity such as methanol and ethanol generally produced fibers with improved mechanical properties, where the fiber toughness shows a strong correlation with solvent polarity. These findings provide insights into assembling BNNTs-based fibers with improved mechanical properties for developing unique applications.