Production of uniform size cell-enclosing silk derivative vehicles through coaxial microfluidic device and horseradish crosslinking reaction

Silk fibroin (SF) as a natural biopolymer holds great potential in biomedical research because of its biocompatibility, easy processability and high strength properties. However, slow gelation time has narrowed its applications, specifically in cell-laden microparticle production due to insufficient crosslinkable moieties. This study aimed to develop cell-laden silk fibroin-phenol (SF-Ph) microparticle through co-flow microfluidic system using SF conjugated Ph moieties whereas covalent crosslinking is mediated with horseradish peroxidase (HRP) in the presence of hydrogen peroxide (H2O2). For this, the SF-Ph was synthesized through carbodiimide condensation crosslinking reaction. Aqueous SF-Ph solution was flowed within the inner channel of the coaxial microfluidic device while liquid paraffin saturated with H2O2 flowed from the outer channel. The monodisperse microparticles in shape and size were formed in various diameters from 80 to 300 µm by altering oil phase velocity. High cell survival rate (>90% cell viability) and 4 times upregulation of mitochondrial activity of enclosed cells in microparticle revealed that the SF-Ph vehicle is the suitable alternative for cell encapsulation and tissue fabrication. It was noticed that encapsulated cells filled the microparticle region until day 21 post-encapsulation. Moreover, the spherical micro-tissue formation resulting from cellular proliferation endorsed by existing cell–cell and cell-matrix interactions which offers an excellent prospect for synthesized SF-Ph and developed method in tissue engineering and regenerative medicine applications.