title: Fabrication of flocculation-resistant pH/ionic strength/temperature multiresponsive hollow microspheres and their controlled release.
abstract: pH/ionic strength/temperature multiresponsive hollow microspheres were successfully prepared by the Ce(IV) initiated grafting polymerization of N-isopropylacrylamide (NIPAm) onto the multilayered polyelectrolyte shells encapsulating the polystyrene sulfonate (PSS) microsphere templates fabricated by the layer-by-layer assembly of chitosan (CS) and alginate (SAL), after etching the templates by dialysis. The hollow structure of the obtained multiresponsive hollow microspheres was characterized by transmission electron microscopy (TEM), which indicated that the inner diameter of the hollow microspheres was about 200 nm. The environmental responsive properties of the multiresponsive hollow microspheres were characterized with dynamic light scattering (DLS) in an aqueous system. The introduction of poly(N-isopropylacrylamide) (PNIPAm) brushes onto the pH/ionic strength dual-responsive hollow microspheres achieved temperature-responsive characteristics. It also could prevent flocculation among the obtained multiresponsive hollow microspheres in a solution with higher salt concentration. Their controlled release of drug molecules (a model hydrophobic drug, dipyridamole (DIP)) was also investigated.
authors.affiliation: State Key Laboratory of Applied Organic Chemistry and Institute of Polymer Science and Engineering, College of Chemistry and Chemical Engineering, Lanzhou University, Lanzhou 730000, China.
authors.forename: Bin
authors.initials: B
authors.lastname: Mu
authors.forename: Peng
authors.initials: P
authors.lastname: Liu
authors.forename: Xiaorui
authors.initials: X
authors.lastname: Li
authors.forename: Pengcheng
authors.initials: P
authors.lastname: Du
authors.forename: Yun
authors.initials: Y
authors.lastname: Dong
authors.forename: Yunjiao
authors.initials: Y
authors.lastname: Wang
mesh_terms: D000178:Acrylamides / Q000737:chemistry*; D000464:Alginates / Q000737:chemistry* / Q000648:ultrastructure; D048271:Chitosan / Q000737:chemistry*; D003692:Delayed-Action Preparations; D004176:Dipyridamole / Q000008:administration & dosage / Q000737:chemistry*; D004337:Drug Carriers / Q000008:administration & dosage / Q000737:chemistry*; D004339:Drug Compounding; D004355:Drug Stability; D005427:Flocculation; D020723:Glucuronic Acid / Q000737:chemistry; D006603:Hexuronic Acids / Q000737:chemistry; D006863:Hydrogen-Ion Concentration; D057927:Hydrophobic and Hydrophilic Interactions; D008863:Microspheres; D009994:Osmolar Concentration; D010316:Particle Size; D010726:Phosphodiesterase Inhibitors / Q000008:administration & dosage / Q000737:chemistry*; D058105:Polymerization; D011137:Polystyrenes / Q000737:chemistry*; D012995:Solubility; D013499:Surface Properties; D013696:Temperature
chemical_list: D000178:Acrylamides; D000464:Alginates; D003692:Delayed-Action Preparations; D004337:Drug Carriers; D006603:Hexuronic Acids; D010726:Phosphodiesterase Inhibitors; D011137:Polystyrenes; D004176:Dipyridamole; C003321:polystyrene sulfonic acid; D020723:Glucuronic Acid; D048271:Chitosan; C067295:N-isopropylacrylamide