pH-sensitive microspheres obtained by derivatized dextran

In this paper we describe the starting materials and the experimental conditions used to prepare hydrogels, based on dextran, by radical copolymerization, which are appropriated for pharmaceutical and biomedical applications. pH-sensitive hydrogel microspheres composed of glycidyl methacrylate dextran (GMD) and methacrylic acid (MA) were prepared by radical copolymerisation for drug delivery. GMD was synthesized by coupling of glycidyl methacrylate to dextran. A water solution of GMD, MA and N,N′ ethylene bis acrylamide (EBA) was added to an organic phase (n-hexane and carbon tetrachloride); the mixture was treated with Span85, Tween85, N,N,N′,N′ tetramethylethylendiamine and ammonium peroxydisulfate (radical initiator). The microspheres obtained showed narrow dimensional distribution, spherical shape, high swelling ratio and a pH dependent swelling behavior that increased in basic medium.