Polymeric particles having a biodegradable gelatin or aminodextran coating and process for making same

Claim 1

Discrete colloidal particles having a surface coating provided with a plurality of pendent functional groups, said particles consisting: (a) a polymeric, non-gelatin, non-aminodextran core selected from the group consisting of polymeric substances which have surface amine-reactive functional groups and polymeric substances which do not have surface amine-reactive groups; (b) said coating selected from the group consisting of a type A, acid cured gelatin of Bloom in the range of about 60 to 300 and an aminodextran; (i) said gelatin coating being crosslinked by a chemical crosslinking agent, or (ii) said aminodextran coating having a molecular weight in the range of 10,000 to 2 million, and, (1) always being crosslinked by a chemical crosslinking agent when said aminodextran is coating a core substance which does not have surface amine-reactive groups or (2) being either not crosslinked or crosslinked by a chemical crosslinking agent when said aminodextran is coating the surface of a core substance which has surface amine-reactive groups and said coating is by covalent coupling of said aminodextran to said core surface by a reaction between said amine-reactive groups and aminodextran amine groups; and (c) functional groups covalently attached to said gelatin and aminodextran coatings.