3D/3.5D Extrusion-Printed Electroconductive Carbon-Nanofiber-Embedded Alginate-Gelatin Hydrogel-Based Grafts:...

Area of Science:

• Biomaterials Science
• Tissue Engineering
• Additive Manufacturing

Background:

• Complex soft tissue reconstruction (e.g., urethral, nerve) requires advanced biomaterials with integrated vascularization, mechanical strength, and electroactivity.
• Current tubular tissue-engineered constructs often exhibit insufficient mechanical stability and electroactivity, limiting their clinical success.

Purpose of the Study:

• To investigate the role of carbon nanofibers (CNFs) in enhancing alginate-gelatin hydrogels for 3D extrusion printing of tubular tissue scaffolds.
• To evaluate the impact of CNF incorporation on the structural, mechanical, electrical, and biological properties of the 3D-printed hydrogel constructs for soft tissue regeneration.

Main Methods:

• Alginate-gelatin hydrogel inks were formulated with varying concentrations of carbon nanofibers (CNFs).
• Additive manufacturing (3D extrusion printing) was employed to fabricate tubular constructs using a 3.5D printing approach.
• Characterization included mechanical testing (viscoelasticity, uniaxial tension), electrical conductivity measurements, Micro-CT imaging, surface roughness analysis, cell viability assays (NIH-3T3 fibroblasts), antimicrobial testing, and in vivo studies in Wistar rats.

Main Results:

• Incorporation of 0.75% CNFs significantly improved hydrogel strength, viscoelasticity, printability, and buildability, with enhanced fracture stress and elastic modulus.
• CNF-reinforced hydrogels exhibited improved electrical conductivity (0.5 S/m), interconnected porous structures, and smooth luminal surfaces suitable for tubular grafts.
• In vitro studies showed high fibroblast viability and potent antimicrobial activity against E. coli and S. aureus. In vivo studies demonstrated enhanced vascularization and a favorable immune response without systemic toxicity.

Conclusions:

• Carbon nanofibers (CNFs) are crucial for developing mechanically robust, electroconductive, and biologically responsive alginate-gelatin hydrogels for 3D printing.
• The CNF-reinforced hydrogel system shows significant translational potential for regenerating complex soft tissues, addressing limitations of current tissue-engineered constructs.
• This study highlights a promising strategy for creating advanced biomaterials for clinical applications in soft tissue repair and regeneration.