Diffusion-assisted spherical microgel fabrication using in situ gelable chitosan and dextran

We demonstrated themicrofluidic fabrication ofinsitu gelable chitosan-dextran microgels.In the gelation process, the amine groups of N-carboxyethyl chitosanand the aldehyde groups of oxidized dextran undergo a cross-linking process via imine formation.In order to produce spherical microgels, a water-in-oil emulsion was employed in a microfluidic flow-focusing device for microdroplet generation.N-carboxyethyl chitosan(3wt%) and oxidized dextran(3wt%) in microdropletswere homogenously mixedby diffusion, resulting in insitucross-linking oftwo hydrogels without the use of additional chemicals.The average value of the Young's modulus of the cross-linked microgel was 1.34±0.21 kPa. For cell applications, the viability of 3T3 cells encapsulated in the microgels was evaluated after0, 3, and 4 days using a live/dead assay. The results demonstrated that the viability was well maintained at around 80% in the culture afterfour days. This demonstrates the biocompatibility of the microgels and fabrication process, which is very promising for applications in injectable tissue constructs.