FEATURES OF THE INTERACTION AND FORMATION OF NANOSTRUCTURED CHITOSAN SYSTEMS DURING IONOTROPIC GELATION

Bombyx mori chitosan nanoparticles (ChS NPs) were obtained and the kinetic aspects of their size distribution depending on the degree of nonequilibrium of the synthesis by ionotropic gelation using sodium tripolyphosphate (TPP) were studied. The size of ChS NPs was greatly influenced by the ChS concentration, which varied from 0.5 to 10 mg/ml. The size of the NPs increased from 100 to 300 nm when the ChS concentration increased from 0.5 to 10 mg/ml and while maintaining all other parameters of the reaction. An increase in the ChS to-TPP ratio corresponded to a lower cross-linking density and thus ensured slower kinetics for NP formation alongside the formation of large chitosan/TPP aggregates. There was an almost threefold increase in the particle size when the pH of the medium increased from 3.8 to 4.7; thus, the size of ChS NPs depends on the pH of the solution. There was a slight agglomeration of NPs from 363 to 642 nm with an increase in the NP synthesis time from 4 to 24 h. According to calculations, the maximum interaction energy is 50.4 and 69.4 kcal/mol for deprotonated TPP (P3O105-); after adiabatic transfer of the proton, the value decreases to 32.9–33.5 kcal/mol. The maximum interaction energy is –12.8 kcal/mol for the initially protonated TPP (H4P3O10-).