Manufacturing protein microspheres

Abstract

Processes for producing biocompatible and biodegradable protein microspheres with controlled porosity and microsphere sizes are disclosed. Generally, the processes are accomplished as follows: (a) dissolving a source of protein in a mildly acidic or basic aqueous medium, in the presence or absence of a biomodifying agent, (b) adding a cross-linking reagent to the dissolved protein molecules in an amount effective subsequently to cross-link the protein molecules without gelation; (c) adding a water soluble surfactant to modify the surface of the partially cross-linked protein molecules, (d) adding a water soluble organic desolubilizer to desolubilize the protein molecules to allow cross-linkage of nearby protein molecules into water-insoluble microspheres. Alternatively, the cross-linking step of (b) is employed after desolvation of the microspheres. Incorporation of the biomodifying agent, if any, can be achieved by prior bonding to the protein molecules, addition during the formation of microspheres, or addition after the formation of the irreversible and stable microspheres. The microspheres produced by said processes are also disclosed.