Formation, structure, properties of chitosan aspartate and metastable state of its solutions for obtaining nanoparticles

Chitosan (200 kDa) dissolution in an aqueous solution of L-aspartic acid, physicochemical properties and features of the resulting chitosan salt were studied by conductometry, potentiometry, viscometry, turbidimetry, IR and NMR spectroscopy, and X-ray diffractometry. Chitosan aspartate is a water-soluble hydrated polymorph exhibiting properties of a cationic polyelectrolyte with an effective macromolecular coil radius 60-75 nm. The specific conductivity, dielectric constant, viscosity and pH of the chitosan - L-aspartic acid - water system change over time after preparation due to counterion-polycation association to form ion pairs, multiplet structures, and their subsequent aggregation. As a result, nanoparticles (40-90 nm) are formed after -24 h, microparticles (0.6-1.4 mu m) are after -48 h, and precipitation occurs after 72-96 h. The precipitated phase is a water-insoluble chitosan salt with a developed system of H-bonds and high crystallinity degree. Chitosan nanoparticles have high biocompatibility and the ability to accelerate the proliferative activity of epithelial cells. Hypothesis: Ion pairs and multiplets are formed in the chitosan - L-aspartic acid - water system due to counterion association, which leads to phase segregation of the polymer substance at the level of nanoparticles and microparticles.

Automated summary

The dissolution of chitosan and L-aspartic acid in an aqueous solution was studied, along with the resulting chitosan salt properties over time. Changes in conductivity, viscosity, pH, and the formation of nanoparticles and microparticles were observed as ion pairs and multiplets formed in the system.