Encapsulating particles with coatings that conform to size and shape of the particles

Abstract

Particles such as islet cells are encapsulated by a method that forms a coating of uniform thickness that conforms to the size and shape of the particles. Two substantially immiscible liquids of different densities are provided in a container as upper and lower liquids such that an interface exists between the liquids. The upper liquid is less dense and has a greater viscosity than the lower liquid which is a coating liquid containing particles to be encapsulated. A tube is positioned in the upper liquid such that an orifice of the tube is above the interface. A pump connected to the tube sucks liquid through the tube at a rate sufficient to form a spout containing substantially the lower liquid extending between the interface and the tube orifice. The spout has maximum diameter at the interface and decreases in diameter as the spout approaches the tube orifice. Particles in the lower liquid are drawn up through the spout as liquid is withdrawn, and coated particles are released from the spout at a point where the diameter of the spout is less than the diameter of the particles, and the coated particles flow through the tube. The coating liquid may be a pre-polymer that can be polymerized and crosslinked after coating. The coated particles have therapeutic applications such as administering coated islet cells to treat diabetes.