Carboxymethylated curdlan as a promising candidate for 3D printing bioink: Its structural characterization, printability and biocompatibility

Curdlan (CD), as a typical β-glucan, is becoming popular as a candidate for intelligent functional materials in the food industry and biomedicine. However, the water insolubility of CD limits its widespread application. Carboxymethylated derivatives of CD with different degrees of substitution (DSs) were fabricated. The structures were accurately characterized using Fourier transform infrared (FT-IR) spectroscopy, X-ray diffraction (XRD), nuclear magnetic resonance (NMR), atomic force microscopy (AFM), and solution conformation analysis to explore the rheological properties and printability of carboxymethylated curdlan (CMCD). The cytotoxicity in vitro and biocompatibility in vivo for 3D printing scaffolds were systematically evaluated. This indicated that carboxymethylation significantly altered the crystal structure of CD, the CMCD with the DS greater than 0.49 showed calcium ion crosslinking properties and was in a state suitable for printing, making its rheological behavior more appropriate for specific applications, which may serve as a rapid prototyping of material for hydrogels in 3D printing bioinks. The printability of CMCD was not only related to the DS but also depended on its concentration. CMCD scaffolds exhibited excellent biocompatibility and low immunogenicity. These results provide new insights and approaches for the application of CD-based biomaterials in tissue engineering and related disciplines.