Influence of Boron Nitride Nanosheets on the Properties of Gelatin-Chitosan Bioinks for Extrusion-Based 3D...

In recent years, there has been increasing interest in developing functional bioink systems that better replicate biological and biochemical microenvironments while maintaining high print fidelity and cell viability. This study reports the development and characterization of gelatin-chitosan-based bioinks reinforced with hexagonal boron nitride nanosheets (BNNSs) for extrusion-based 3D bioprinting. Structural, chemical, and morphological analyses demonstrated the successful incorporation of BNNSs without the formation of new chemical bonds, while minor shifts in amide bands indicated enhanced hydrogen bonding and physical interactions. Rheological studies revealed that gelatin concentration was the primary factor governing viscosity, whereas BNNSs provided a composition-dependent reinforcing effect. Notably, at a low shear rate (0.001 s^-1), viscosity increased from 2865 Pa·s for low concentration gelatin bioinks to 9322 Pa·s for BNNS-containing high concentration formulations, representing more than a threefold increase. In contrast all formulations exhibited low viscosities below 3 Pa·s at 100 s^-1, confirming favorable extrusion behavior. Viscoelastic analysis further showed lower tan δ values for high gelatin content formulations, indicating elastic-dominant behavior and improved shape retention at printing temperatures. BNNS incorporation slightly reduced the glass transition temperature by approximately 10°C while preserving blend compatibility, contributing to enhanced thermal responsiveness and more uniform temperature distribution during printing. Printability analysis demonstrated that BNNSs improved shape fidelity in high-viscosity formulations, yielding printability index (Pr) values close to unity (Pr ≈ 0.94) and stable filament formation. Swelling and degradation studies showed that BNNS-containing 7.5% gelatin scaffolds exhibited reduced swelling and retained approximately 70% structural integrity after 14 days, whereas low-polymer formulations underwent rapid degradation. Cell viability assessments confirmed improved fibroblast adhesion and proliferation on BNNS-containing scaffolds. The incorporation of BNNSs improves the rheological and thermal characteristics of the gelatin-chitosan bioinks and positively influences cell response. These findings suggest that BNNS-containing formulations provide a more stable and thermally responsive printing platform.