Red-blood-cell-shaped chitosan microparticles prepared by electrospraying

•Red-blood-cell-shaped (RBC) chitosan microparticles were fabricated by electrospraying.•A novel strategy was developed to control solvent diffusion via solvent evaporation.•Control of solvent diffusion was crucial to form RBC-shaped chitosan microparticles.

Red-blood-cell-shaped chitosan microparticles with acid-triggered dissolution and auto-fluorescence were successfully fabricated by a simple strategy combining electrospraying with a solvent diffusion process controlled by solvent evaporation. The sizes of the prepared chitosan microparticles were relatively uniform. Control of the solvent diffusion process was crucial for the formation of microparticles with concave morphology. A chitosan aqueous solution containing 20 vol% ethanol as the evaporable solvent and 30 vol% dimethyl sulfoxide as the diffusible solvent was optimal for preparation of chitosan microparticles with the desired red-blood-cell-like size and shape. These chitosan microparticles will be highly attractive for many biological and biomedical applications.

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