Another approach for crosslinking polysaccharide-based hydrogels involves formation of disulfide bonds and Schiff bases. In the latter strategy, aldehyde groups are easily introduced in the backbone of several polymers (e.g., ALG, HA, Dex, ) through oxidation with sodium periodate (NaIO4) and they subsequently react with primary amine-containing macromolecules. (e.g., carboxymethyl chitosan (CMCS), glycol chitosan (gCS), Gel, and PAMAM dendrimers ). The reaction occurs under mild conditions (i.e., neutral pH, 25-37 °C) compatible with biological applications. In