Abstract: There is provided a method for producing hydrogel microparticles with spherical shape and having a narrow-disperse or mono-disperse size distribution. At least one temporary crosslinker such as those of formula (I), (Ila)-(Ilf) and at least one permanent crosslinker comprising two or more vinyl groups, such as: divinylbenzene (DVB), ethylene glycol dimethacrylate (EGDMA),diethyleneglycol dimethacrylate (DEGDMA), N,N?-methylenebisacrylamide (MBA), oligo/poly ethyleneglycol dimethyacrylate, 1,4-butanediol dimethacrylate, and 1,6-hexanediol dimethacrylate are combined in an organic solvent having a polarity suitable for a precipitation polymerization to occur. The precipitation polymerization is allowed to take place without the addition of surfactant and/or stabilizer and/or the formed microparticles comprise less than 1% surfactant and/or stabilizer. These microparticles may be further functionalized to obtain amine and carboxylic acid units by functionalizing the monomers of the temporary crosslinkers.

Abstract: A novel charge-shifting copolymer is provided comprising a first charge-shifting monomer that is cationic under physiological conditions and which possesses cationic groups that may be converted into anionic groups under physiological conditions, a second monomer comprising at least one primary amine that is not convertible to an anionic group under physiological conditions, and optionally, one or more monomers which are polar uncharged monomers. A hydrogel system incorporating this copolymer, as well as a capsule system, are also provided.

Abstract: A polymer matrix is provided comprising an amine-containing polyampholyte covalently crosslinked with an electrophilic polymer to yield an immunocompatible polymer matrix. A hydrogel system incorporating the polymer matrix is also provided.

Abstract: A novel charge-shifting copolymer is provided comprising a first charge-shifting monomer that is cationic under physiological conditions and which possesses cationic groups that may be converted into anionic groups under physiological conditions, a second monomer comprising at least one primary amine that is not convertible to an anionic group under physiological conditions, and optionally, one or more monomers which are polar uncharged monomers. A hydrogel system incorporating this copolymer, as well as a capsule system, are also provided.

Abstract: A polymer matrix is provided comprising an amine-containing polyampholyte covalently crosslinked with an electrophilic polymer to yield an immunocompatible polymer matrix. A hydrogel system incorporating the polymer matrix is also provided.

Abstract: An immuno-compatible hydrogel system is provided that is resistant to protein binding. The hydrogel system is prepared by contacting a hydrogel solution with a cross-linking agent to form a gel, exposing the gel to an aqueous solution comprising a first polyelectrolyte to form a polyelectrolyte-coated hydrogel, exposing the polyelectrolyte-coated hydrogel to a second polyelectrolyte to form a crosslinked matrix and exposing the matrix to conditions which eliminates, or at least reduces, protein binding sites on the matrix.

Abstract: An immuno-compatible hydrogel system is provided that is resistant to protein binding. The hydrogel system is prepared by contacting a hydrogel solution with a cross-linking agent to form a gel, exposing the gel to an aqueous solution comprising a first polyelectrolyte to form a polyelectrolyte-coated hydrogel, exposing the polyelectrolyte-coated hydrogel to a second polyelectrolyte to form a crosslinked matrix and exposing the matrix to conditions which eliminates, or at least reduces, protein binding sites on the matrix.

Abstract: A novel hydrogel system is provided. The hydrogel system comprises a biocompatible hydrogel core having dispersed therein a covalently crosslinked polymer matrix. The hydrogel system is useful per se or as an encapsulation system.

Abstract: It is known to encapsulate various materials in polyurea microcapsules, but obtaining satisfactory microcapsules incorporating alcoholic materials has proven difficult. A process has now been found where polyurea microcapsules are formed by interfacial polymerization between an aqueous phase and a water-immiscible phase, and properties, particularly the solubility parameters, of the water immiscible phase are closely matched to corresponding properties of the polyurea. Microcapsules prepared by this process have improved stability, mechanical strength and controlled release properties.