Production and physicochemical characterization of a new amine derivative of gellan gum and rheological study of derived hydrogels.

The production of an amine derivative of gellan gum, named GG-EDA, was here obtained by functionalizing the polysaccharide backbone with pendant ethylenediamine moieties. The obtained derivative was characterized by spectroscopic, colorimetric, chromatographic and rheological analyses to study the effect of the free amino groups on the physicochemical properties of the macromolecule. A titration experiment was conducted to study the acid-base dissociation constants in aqueous media for the carboxylic and amino groups in the GG-EDA and to shed light on the possibility that the derivative shows a polyampholyte structure under physiological conditions. The rheological analysis conducted on both physical and chemical hydrogels based on GG-EDA revealed that the presence of amino groups plays a fundamental role in influencing the viscoelastic properties and stability of the produced samples.