(14a) Monodisperse Erythrocyte-Sized and Acid-Soluble Chitosan Microspheres Prepared Via Electrospraying

Monodisperse erythrocyte-sized and acid-soluble chitosan microspheres are successfully prepared by electrospraying method for the first time.  Effects of the physical properties of polymer solution and the condition parameters of electrospraying process on the size and size distribution of the chitosan microspheres are systematically studied, to optimize the conditions for preparation of chitosan microspheres with our specific requirements.  The microsphere size is mainly controlled by the viscosity of spray liquid, and the microsphere monodispersity mainly depends on electric conductivity of spray liquid, the flow rate and the needle size.  Under the optimized condition, monodisperse chitosan microspheres with average diameter of 6.4 µm, which is just similar to the erythrocyte size, are prepared with narrow size distribution (CV < 3%).  Due to the use of terephthalaldehyde as cross-linker via formation of Schiff base bonds, the prepared chitosan microspheres can maintain structural integrity and show green fluorescence in neutral medium, but display rapid acid-triggered decomposition.  The prepared erythrocyte-sized and acid-soluble chitosan microspheres are highly attractive as the promising substitutes of blood samples for calibration of hematology analyzers and flow cytometers.