Microfluidic Fabrication of Monodisperse Hyaluronic Acid Microspheres with Excellent Biocompatibility and Tunable Physicochemical Properties

A simple and efficient method based on droplet microfluidics is developed for controllably fabricating monodisperse hyaluronic acid (HA) microspheres with excellent biocompatibility and tunable physicochemical properties. By using adipic dihydrazide (ADH) as the cross-linking agent in the HA dispersed phase and 1-ethyl-3-(3-(dimethylamino)propyl)carbodiimide (EDC) as the activator in the receiving solution, chemically cross-linked HA microspheres with uniform sizes and excellent biocompatibility can be efficiently obtained in one step with the microfluidic emulsion droplets as templates. By adjusting the dimensions of the microfluidic devices as well as the flow rates of the dispersed and continuous phases, the sizes of the droplet templates and the resultant cross-linked HA microspheres can be precisely controlled. The swelling property, elasticity property, and stability of the HA microspheres can be regulated by adjusting the EDC concentrations in the receiving solutions and the mass ratios of ADH to HA in the dispersed phases. The in vitro blood compatibility and cell experiments demonstrate that the fabricated HA microspheres have excellent biocompatibility. The proposed strategy and the results in this study provide valuable guidance for the simple and efficient preparation of monodisperse HA microspheres with excellent biocompatibility and tunable physicochemical properties, which are highly desired for various applications.