Encapsulation of labile biological material

A process for encapsulating a chemically active core material in a porous capsule membrane from which the active core material cannot diffuse, said membrane comprising a polymer selected from the group consisting of polyamides, polyesters, polyureas, polycarbonates, and polysulfonamides, said process comprising the steps of:

• 1. preparing a solution of a first monomer and said core material in a first solvent selected from the group consisting of water and hydrophilic solvents, said first monomer being selected from the group consisting of polyols and diamines;
• 2. emulsifying said solution in a hydrophobic solvent in which the first monomer is slightly soluble to produce a hydrophilic discontinuous phase;
• 3. adding a second monomer selected from the group consisting of diacids, diacid halides, diisocyanates, and multifunctional sulfonyl halides to said emulsion to cause an interfacial polymerization reaction between the first and second monomers at the interface of the phases of the emulsion to form macroporous polymeric capsule membranes about the members of the discontinuous phase;
• 4. separating the capsules produced in step 3 from the hydrophobic solvent to terminate the polymerization reaction;
• 5. resuspending the capsules in a liquid, said liquid being selected to be less soluble with said first monomer than said hydrophobic solvent;
• 6. adding a second portion of said second monomer to the resuspension to cause further polymerization at said capsule membranes to strengthen said membranes and to render them microporous yet impermeable to said core material;
• and
• 7. quenching the polymerization reaction in the resuspension.