Patent ID: 6465226
Filing Date: 2002-10-15
Classification: A61K,B01J

Abstract:
A method for preparing microcapsules containing a core of a biologically active substance comprising cells or tissue and having a maximum diameter of 300 micrometers, comprising the steps of:passing a solution of a soluble gellable encapsulating material containing a dispersed biologically active substance comprising cells or tissue through an inner channel of a two-channel spray nozzle having said inner channel and an outer channel for air flow for forming droplets containing a core of the biologically active substance; causing the droplets to separate from the two-channel spray nozzle by air flow from the outer channel, wherein air pressure in the outer channel, diameter of the inner channel, diameter of the outer channel or flow rate of the solution containing the dispersed biologically active substance through the inner channel is selected for obtaining droplets having a volume of 1.5-4 times the volume of the biologically active substance that forms the core of a microcapsule; passing the droplets to a precipitation bath containing a solution of bivalent barium cations where the soluble gellable encapsulating material is gelled by the bivalent barium cations cross-linking the gellable encapsulating material to form microcapsules containing the biologically active substance and microcapsules not containing the biologically active substance, wherein said microcapsules have a maximum diameter of 300 micrometers; and, supplying the microcapsules to a density centrifugal separator where a medium having a density gradient adjusted to a density higher than the density of microcapsules not containing the biologically active substance and a density lower than the density of the microcapsules containing the biologically active substance separates the microcapsules not containing the biologically active substance for obtaining the microcapsules containing a core of the biologically active substance and having a maximum diameter of 300 micrometers.