Synergistic DLP bioprinting of high-fidelity nerve guidance conduits using a chitosan–collagen methacryloyl conductive bioink with neurotrophic factors

Peripheral nerve injuries continue to impose significant clinical challenges, prompting the development of electroactive, biopolymer-based conduits. In this study, we synthesized methacrylated chitosan (ChiMA) and fish-derived collagen methacryloyl (ColMA), confirmed by NMR signals and FTIR peaks, then formulated a bioink enriched with choline bicarbonate ionic liquid (IL) for electrical conductivity (~10−3 S/cm) and vitamin B₆ for neurotrophic support. Rheological characterization revealed shear-thinning behavior, with viscosity decreasing from 1100 mPa·s at low shear to 300 mPa·s at high shear. Using digital light processing (DLP) bioprinting, we produced tubular nerve conduits with feature resolution down to 50 μm and wall thickness of 0.5 mm, achieving high-fidelity structures without compromise to photocrosslinking kinetics. Mechanical characterization demonstrated a compressive modulus of 13.0 ± 1.3 kPa, while in vitro stability studies showed 99.25% mass retention over 35 days under enzymatic conditions. Human mesenchymal stem cells (hMSCs) cultured on the printed constructs exhibited high cytocompatibility (>120% relative cell viability), with enhanced metabolic activity relative to 2D controls and ~ 93% viability based on live–dead staining. Neurogenic responses were assessed at the gene-expression level, where qRT-PCR analysis indicated elevated expression of neural-associated markers (HNK-1, PRPH, and NEFH) compared to undifferentiated controls. Taken together, these findings suggest that the DLP-printed ChiMA–ColMA–IL constructs provide a permissive, neuro-supportive microenvironment that maintains high cell viability and modulates neurogenic marker expression under induction conditions. Overall, this work presents a synergistic chitosan–collagen methacryloyl bioink with high DLP printability, mechanical robustness, and in vitro neuro-supportive characteristics. This platform provides a materials and fabrication foundation for high-fidelity DLP-printed soft-tissue and nerve guidance constructs.

DLP bioprinting; Bioinks; Nerve conduits; Soft tissue engineering; Chitosan; Collagen