Reactivity of chitosan derivatives and their interaction with guanine: A computational study

The present study delves into the reactivity of a few chitosan derivatives (CSDs) and their interaction with guanine in vacuum and in different phases. Increase in the polarity of the solvent lowers reactivity of the chosen derivatives (evaluated by using reactivity descriptors). Interaction between the CSDs and guanine (measured by interaction energy) weakens in solvent media and CSD-guanine interaction is weaker than the interaction between guanine and unmodified chitosan (CS). Chemical stability of CSD-guanine adducts remains similar to that of CS-guanine adduct in both polar and non-polar media. Moreover, CSD-guanine adducts exhibit comparable thermodynamic stability (quantified by free energy of solvation, Delta G (sol)) to that of unmodified CS-guanine adduct in non-polar solvent but in polar medium they are immensely destabilized in comparison to CS-guanine adduct. Observed theoretical results are expected to provide guidance for future relevant experimental research on gene delivery by CS derivatives.