title: Redox-responsive alginate microsphere containing cystamine.
abstract: Redox-responsive microspheres were prepared by solidifying the alginate- and cystamine-containing water droplets of O/W emulsion using calcium ion. Emulsions were prepared using alginate/cystamine mixture solution whose the carboxylic group/the amino group molar ratio was 1:1, 1:2, and 1:3, and whose the total concentration was kept to 2% (w/v). The microspheres on Scanning electron microscopy photographs were almost spherical and they were less than 1 μm in diameter. According to the energy-dispersive X-ray spectroscopy, the sulfur content of the microspheres was found to be 6.1, 11.4, and 14.8% (w/w), respectively, not markedly different from the calculated content. The release degree of blue dextran loaded in the microspheres was higher as the cystamine content was higher. Microspheres released almost the same amount of dye regardless of dithiothreitol (DTT, a reducing agent) concentration when the cystamine content was relatively low (e.g. 14.5% (w/w)), whereas they released dye in DTT concentration-dependent manner when the cystamine content was relatively high (e.g. 27.0 and 35.1% (w/w)). The light scattering intensity of alginate/cystamine mixture solution was stronger at a larger amount of cystamine, indicating that cystamine could cross-link alginate chains. The light scattering intensity decreased with increasing DTT concentration, possibly because of the breakdown of the disulfide bond of cystamine. The breakdown of the disulfide bond could account for why the DTT concentration-dependent release of dye loaded in the microspheres was observed.
authors.affiliation: a Department of Medical Biomaterials Engineering , College of Biomedical Science and Institute of Bioscience and Biotechnology, Kangwon National University , Chuncheon , Republic of Korea.
authors.forename: Kyeongnan
authors.initials: K
authors.lastname: Kwon
authors.affiliation: a Department of Medical Biomaterials Engineering , College of Biomedical Science and Institute of Bioscience and Biotechnology, Kangwon National University , Chuncheon , Republic of Korea.
authors.forename: Jin-Chul
authors.initials: JC
authors.lastname: Kim
mesh_terms: D000464:Alginates / Q000737:chemistry*; D003538:Cystamine / Q000737:chemistry*; D003911:Dextrans / Q000737:chemistry; D004220:Disulfides / Q000737:chemistry; D004229:Dithiothreitol / Q000737:chemistry; D004337:Drug Carriers / Q000737:chemistry*; D065546:Drug Liberation; D020723:Glucuronic Acid / Q000737:chemistry; D006603:Hexuronic Acids / Q000737:chemistry; D008863:Microspheres; D010084:Oxidation-Reduction; D019163:Reducing Agents / Q000737:chemistry; D014867:Water / Q000737:chemistry
chemical_list: D000464:Alginates; D003911:Dextrans; D004220:Disulfides; D004337:Drug Carriers; D006603:Hexuronic Acids; D019163:Reducing Agents; D014867:Water; D020723:Glucuronic Acid; C017080:blue dextran; D003538:Cystamine; D004229:Dithiothreitol
keywords: Redox; alginate; cystamine; emulsion; microsphere; release