Preparation and some physicochemical properties of cross-linked poloxamer hydrogel spheres

The principal purpose of this paper is to report the preparation of cross-linked poloxamer hydrogel spheres in an aqueous two-phase system without the use of organic solvent and additional emulsifier and physicochemical properties related to drug release. Poloxamer 188 was modified with methacryloyl chloride to obtain the polymerizable derivative (macromer). The aqueous solution of the macromer was mixed with dextran/magnesium sulfate aqueous solution to form a water-in-water emulsion system. After polymerizing the macromer in the dispersion phase, nonporous particles with a mean diameter of micron level were prepared. Both the mean diameter and swelling ratio of spheres can be tailored by varying the starting composition of the preparations. The drug release experiments indicate that the release of vitamin B12 entrapped in the spheres follows first-order kinetics.