Polysaccharides enzymatic modification to control the coacervation or the aggregation behavior: A thermodynamic study

The effect of enzymatic modification of polysaccharides on the formed supramolecular structures was studied. Gum Arabic and chitosan were modified by covalent grafting of ferulic acid oxidation products so that they could establish new interactions such as 7C interactions. The stoichiometry of the interaction was studied by ITC measurements, as well as its strength and related thermodynamic parameters. These experiments were supported by Zeta potential and turbidity measurements and optical macroscopy observations. Grafting of phenolic compounds onto the polymers increased their ability to exhibit 7C -7C stacking and 7C-cation interactions and led to the formation of various supramolecular structures. For native gum Arabic and chitosan assemblies, the stoichiometry value determined by ITC was consistent with optical microscopy, macroscopic observations and Zeta potential (around a molar ratio gum Arabic:chitosan of 3). The structures formed were coacervates. For the modified polymers, the optimal molar ratio determined by Zeta potential measurements (3.27) differed from the one determined by ITC (6.3). This meant the formation aggregates was not only due to electrostatic interactions but also to other type of interactions (new 7C -7C stacking and 7C-cation interactions). It was concluded that by modifying the polymers, it was possible to control the supramolecular structures formed.

Automated summary

The effect of enzymatic modification on polysaccharides in forming supramolecular structures was investigated through covalent grafting of ferulic acid oxidation products onto Gum Arabic and chitosan. These modifications allowed for the establishment of new interactions and the formation of various supramolecular structures. The interactions were found to be not only electrostatic but also involved other types of interactions, leading to the need for different measurement methods for determination and control of the supramolecular structures formed.