Investigation of oxidized alginate/gelatin/ carboxymethyl cellulose hydrogels as a bioink: Optimization of composition for extrusion-based bioprinting

Skin bioprinting has gained significant attention as a transformative method for treating skin injuries due to its ability to construct complex tissue-engineered structures. This study investigates the effect of varying weight ratios of Oxidized Alginate (OAlg), Gelatin (Gel), and Carboxymethyl Cellulose (CMC) on bioink formulations using extrusion-based bioprinting. Alginate was oxidized with sodium metaperiodate, achieving 10% oxidation. Hydrogels were formulated with OAlg at concentrations of 10%, 15%, and 20% (w/v), while Gel and CMC were held constant at 5% (w/v) and 15% (w/v), respectively. Chemical structure analysis supported the formation of crosslinked interactions within the hydrogels. The optimal formulation, containing 20% (w/v) OAlg, gelled in approximately 30 s and demonstrated good structural stability during printing. Rheological assessments revealed shear-thinning behavior and appropriate viscosity for bioprinting across all formulations. After 28 days, the 20% (w/v) OAlg hydrogel exhibited a 49% degradation rate. Unlike conventional OAlg–Gel systems, the incorporation of CMC provided enhanced viscosity control, improved filament fidelity during extrusion, and improved structural stability during printing without the need for additional ionic crosslinkers. Three-dimensional printing tests demonstrated that this formulation provided superior printing uniformity, and cell viability assays revealed a 93% survival rate for skin fibroblast cells, indicating its potential for further investigation in skin tissue engineering applications.