Polysaccharide-based networks from homogeneous chitosan-tripolyphosphate hydrogels: synthesis and characterization

Polysaccharide networks, in the form of hydrogels and dried membranes based on chitosan and on the cross-linker tripolyphosphate (TPP), were developed using a novel approach. TPP was incorporated into chitosan by slow diffusion to favor a controlled gelation. By varying chitosan, TPP, and NaCl concentration, transition from inhomogeneous to homogeneous systems was achieved. Rheology and uniaxial compression tests enabled to identify the best performing hydrogel composition with respect to mechanical properties. FTIR, (31)P NMR, and spectrophotometric methods were used to investigate the interaction chitosan-TPP, the kinetics of phosphates diffusion during the dialysis and the amount of TPP in the hydrogel. A freeze-drying procedure enabled the preparation of soft pliable membranes. The lactate dehydrogenase assay demonstrated the biocompatibility of the membranes toward fibroblasts. Overall, we devised a novel approach to prepare homogeneous macroscopic chitosan/TPP-based biomaterials with tunable mechanical properties and good biocompatibility that show good potential as novel polysaccharide derivatives.