One-step synthesis of chitosan-silica hybrid microspheres in a microfluidic device

This article describes a simple microfluidic method to fabricate chitosan-silica hybrid microspheres in one step. We dissolved tetraethoxysilane (TEOS) into a chitosan/acetic acid aqueous solution to form a chitosan-silica sol, and then emulsified it in an organic phase mainly containing n-octanol and an organic base triotylamine (TOA) via a co-axial microfluidic device. The formed aqueous droplets were solidified because of the extraction of acetic acid and water to the organic phase. The simple method presented has the advantages of controllable sphere diameter, narrow size distribution and good sphericity. The porous structures of the microspheres were displayed by SEM images. It is found that the inner and surface structures can be controlled by adjusting the solidification reagent component. Furthermore, we chemically grafted bovine serum albumin (BSA) on the microspheres. The existence of silica in the chitosan spheres can enhance both of mechanical intensity and protein loading capacity of the microspheres.