Precipitation parameters and the cytotoxicity of chitosan hydrochloride microparticles production by supercritical assisted atomization

Sub-micrometric chitosan hydrochloride (CH) particles were produced using a supercritical assisted atomization (SAA) process with supercritical carbon dioxide as the spraying medium and 50% (v/v) ethanol aqueous solution as the solvent. Adding ethanol to the aqueous solution increased the solubility of CO2, enhanced the second atomization in SAA, and reduced CH particles size. The results revealed that low concentrations of the CH solution, high saturator temperatures, and an optimized CO2-to-CH solution flow ratio effectively minimized the mean particle size. A marked decrease in the transepithelial electrical resistance of Caco-2 cell monolayers incubated with CH suspensions demonstrated that the interaction between the fine CH particles and Caco-2 cells produced an efficient tight junction opening effect. Cytotoxicity experiments showed that a low concentration of the CH suspension and large CH particle size caused high Caco-2 cell viability. The biological properties of the CH particles were investigated and could be used in drug delivery system.