Alginate Microspheres Loaded with Animal Cells and Coated by a Siliceous Layer

Animal cells or cell aggregates are suspended in Na-alginate solution and extruded under a flow of air saturated with silicon alcoxides. The immediate formation of a sol-gel siliceous membrane on the microdrop surface allows the reaction with Ca²⁺⁺, leading to solid Ca-alginate, and yields homogeneous, stable microcapsules 200 m in diameter. The cell function of the encapsulated biomass were tested in specific protein production, which is not affected by the siliceous membrane protection of Ca-alginate microcapsules. This fact, and the observed increase in mechanical stability and chemical durability, indicate that valuable features of silica encapsulation are added to those proper to Ca-alginate.