Characterization and antimicrobial activity of 3D-printed scaffolds with high and low molecular weight chitosan

Tissue engineering provides an innovative strategy for regenerating damaged tissues through the use of three-dimensional (3D) scaffolds, which can be fabricated using advanced techniques such as 3D printing. This approach enables the precise and reproducible design of scaffolds with critical architectural features, including interconnected porosity. One of the main challenges in tissue regeneration, particularly in the oral cavity, is bacterial contamination, which can trigger inflammatory responses and hinder healing. Therefore, scaffolds with inherent antimicrobial properties hold great clinical potential. However, the antimicrobial properties of chitosan vary depending on its molecular weight and the bacterial species tested. This study aimed to fabricate and characterize 3D-printed chitosan-based scaffolds and to assess their antimicrobial activity. Bioinks were prepared using high (CH-HMW) and low (CH-LMW) molecular weight chitosan, and their rheological properties were evaluated to confirm pseudoplastic behavior suitable for extrusion-based printing. Chitosan–alginate scaffolds were printed and characterized by scanning electron microscopy (SEM), and their antimicrobial efficacy was tested against ATCC reference strains: Escherichia coli, Streptococcus mutans, Staphylococcus aureus, and Enterococcus faecalis . The results indicated that 3% CH-HMW and 6% CH-LMW formulations exhibited suitable printability. Notably, 3% CH-HMW demonstrated significantly enhanced antimicrobial activity against all tested strains compared to 6% CH-LMW and the positive control. These findings highlight 3% CH-HMW as a promising material for clinical applications in oral bone regeneration, where antimicrobial performance is critical. Future studies should evaluate its biocompatibility and explore synergistic combinations with other materials to further improve scaffold functionality and tissue integration.