Self-assembling nano- and microparticles of chitosan L- and D-aspartate: preparation, structure, and biological activity

Our comprehensive study of solutions of chitosan (CS) D-aminoglucan in L- and D-aspartic acid (AspA) revealed the effects of counterionic association (self-organization) with the transition of macromolecules to the ionomeric state and phase segregation of the polymer substance into chiral nano- and microparticles. Optimal conditions for stabilizing particle dispersions by functionalizing their surface with a polysiloxane shell have been developed (pharmacologically active silicon tetraglycerolate was used for the first time as a sol-gel precursor). The effect of the L- and D-enantiomer of AspA on the structure, size, shape, and zeta potential of nano(micro)particles was studied by IR spectroscopy, dynamic light scattering, and electron and optical microscopy. It was found that chiral particles of CS·L-AspА and CS·D-AspА are non-toxic, hemo- and biocompatible, and also exhibit high growth-stimulating activity for test plants with the best effect for homochiral D-glucan·D-AspА particles. Experiments in vitro and in vivo revealed that chiral CS·L-(D-)AspA nano(micro)particles are biomimetic of rhizospheric bacteria Pseudomonas aureofaciens and could function as an immunizing elicitor, a curing fungicide, and a protective pesticide.

The research was supported by Russian Science Foundation Grant No. 22-23-00320, https://rscf.ru/project/22-23-00320/