Assessing rheological properties of oxidized Moringa oleifera gum and carboxymethyl chitosan‐based self‐healing hydrogel for additive manufacturing applications

Rheology plays a vital role in pneumatic three-dimensional (3D) printing of hydrogels. This study investigates the rheological behavior of a novel self- healing hydrogel (O-MOG/CMCh) formed by a Schiff base crosslinking reaction between oxidized Moringa oleifera gum (O-MOG), a biodegradable antimicrobial polysaccharide, and carboxymethyl chitosan (CMCh), a water-soluble biocompatible cliitosan derivative. Three hydrogel formulations were designed using 5% w/v of CMCh with varied concentrations of O-MOG (3% w/v, 4% w/v, and 5% w/v) and evaluated through rheology analyses, including frequency sweeps, amplitude sweeps, oscillatory thixotropy, and gelation kinetics. These tests revealed that the material has shear thinning, self-healing properties, a high linear viscoelastic region (LVE), and gel formation times ([t.sub.gel]) of 3.23-4.57 min. The hydrogel synthesized with 5% w/v of O-MOG composition exhibited the best characteristics for printability based on rheological assessments, and this composition was used for further printing assessment, where bi-layered 4x4 and 2x2 grids were successfully printed using 22 G (0.41 mm) and 23 G (0.34 mm) syringes. All the constructs had a printability index value of 1 [+ or -] 0.13 and spreading ratios