Fully bio-based supramolecular gel based on cellulose nanowhisker gallate by cyclodextrin host-guest chemistry

Nowadays, supramolecular hydrogels have gained special importance and development of versatile approaches for their preparation as well as their new facile characterization strategies has elicited tremendous scientific interest. Herein, we demonstrate that modified cellulose nanowhisker with gallic acid pendant groups (CNW-GA) could effectively bind with CNW grafted with β-Cyclodextrin (CNW-g-β-CD) through HG interaction to form fully biocompatible and low-cost supramolecular hydrogel. Also, we reported an easy and efficient colorimetric characterization method for confirming HG complexation using naked eye. The possibility of this characterization strategy evaluated both experimentally and theoretically using DFT method. Also, phenolphthalein (PP) was used for visual detection of HG complexation. Interestingly, PP undergoes a rearrangement in its structure in presence of CNW-g-β-CD because of HG complexation that turns the purple molecule into a colorless compound in alkaline condition. Addition of CNW-GA to the resulting colorless solution turned the color to purple again which easily confirmed HG formation.