Influence of solvent variability on the physico-structural properties of nanoscale chitosan biopolymers

Functionalized biopolymers, especially at the nanoscale, boast a broad spectrum of applications. In this context, our laboratory synthesized chitosan, an example of such biopolymers, through the deacetylation of chitin derived from shrimp. The molecular structure of the prepared chitosan was examined using FTIR, which confirmed its similarity to commercially available chitosan. A significant aspect of chitosan’s functionalization largely hinges on its solubility in major solvents, which in turn affects its potential applications. In this study, the DFT:B3LYP/3-21g* model was employed to investigate the influence of various solvents on the structural and physical properties of chitosan. Key parameters such as the total dipole moment (TDM), HOMO/LUMO energy gap, and molecular electrostatic potential (MESP) were calculated to ascertain the effect of solvation on nanoscale chitosan. The findings suggest that solvation enhances chitosan’s reactivity in terms of the TDM, HOMO/LUMO energy gap, and MESP. Additionally, solvation led to minor alterations in chitosan’s structural parameters. To experimentally validate the theoretical outcomes, chitosan was dissolved in several solvents. The FTIR spectrum of each solution was then recorded and juxtaposed against raw (undissolved) chitosan. The analyses showed no modifications in the molecular structure due to solvation.