| 摘要 |
A process for the preparation of a controlled release system, comprising forming of an aqueous two-phase system form at least two water soluble polymers which are incompatible in solution, at least one of these polymers being cross-linkable, the cross-linkable polymer phase being emulsified in the other polymer phase; adding at least one relesable compound which is soluble in the cross-linked polymer phase in the aqueous solution, allowing the releasable compound to diffuse in the cross linkable polymer phase; cross-linking the cross-linkable polymer before or after the releasable compound is added, preferably to a degree that the pores in the cross-liked structure are substantially smaller than the particle size of the releasable compound; and separating the cross-linked structures enclosing the release able compound from the other phase. Further, the invention relates to microspheres, at least 80 wt. % thereof having a particle size of between 100 nanometers and 1000 um, which microspheres are comprised of a degradable, cross-linked polymer encapsulating at least one releasable compound, the pore size of the cross-linked polymer being smaller than the particle size of the releasable compound.
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