title: A novel pulsed drug-delivery system: polyelectrolyte layer-by-layer coating of chitosan-alginate microgels.
abstract: OBJECTIVE
  The aim of this report was to introduce a novel "core-membrane" microgel drug-delivery device for spontaneously pulsed release without any external trigger.
  
  
  METHODS
  The microgel core was prepared with alginate and chitosan. The semipermeable membrane outside the microgel was made of polyelectrolytes including polycation poly(allylamine hydrochloride) and sodium polystyrene sulfonate. The drug release of this novel system was governed by the swelling pressure of the core and the rupture of the outer membrane.
  
  
  RESULTS
  The size of the core-membrane microgel drug-delivery device was 452.90 ± 2.71 μm. The surface charge depended on the layer-by-layer coating of polyelectrolytes, with zeta potential of 38.6 ± 1.4 mV. The confocal microscope exhibited the layer-by-layer outer membrane and inner core. The in vitro release profile showed that the content release remained low during the first 2.67 hours. After this lag time, the cumulative release increased to 80% in the next 0.95 hours, which suggested a pulsed drug release. The in vivo drug release in mice showed that the outer membrane was ruptured at approximately 3 to 4 hours, as drug was explosively released.
  
  
  CONCLUSIONS
  These data suggest that the encapsulated substance in the core-membrane microgel delivery device can achieve a massive drug release after outer membrane rupture. This device was an effective system for pulsed drug delivery.
authors.affiliation: Department of Pharmaceutical Science, Second Military Medical University, Shanghai, People's Republic of China.
authors.forename: Guichen
authors.initials: G
authors.lastname: Zhou
authors.forename: Ying
authors.initials: Y
authors.lastname: Lu
authors.forename: He
authors.initials: H
authors.lastname: Zhang
authors.forename: Yan
authors.initials: Y
authors.lastname: Chen
authors.forename: Yuan
authors.initials: Y
authors.lastname: Yu
authors.forename: Jing
authors.initials: J
authors.lastname: Gao
authors.forename: Duxin
authors.initials: D
authors.lastname: Sun
authors.forename: Guoqing
authors.initials: G
authors.lastname: Zhang
authors.forename: Hao
authors.initials: H
authors.lastname: Zou
authors.forename: Yanqiang
authors.initials: Y
authors.lastname: Zhong
mesh_terms: D000464:Alginates / Q000008:administration & dosage / Q000737:chemistry*; D000818:Animals; D048271:Chitosan / Q000008:administration & dosage / Q000737:chemistry*; D003692:Delayed-Action Preparations; D003911:Dextrans / Q000008:administration & dosage / Q000737:chemistry / Q000493:pharmacokinetics; D016503:Drug Delivery Systems / Q000379:methods*; D016650:Fluorescein-5-isothiocyanate / Q000008:administration & dosage / Q000031:analogs & derivatives / Q000737:chemistry / Q000493:pharmacokinetics; D005782:Gels / Q000008:administration & dosage / Q000737:chemistry*; D020723:Glucuronic Acid / Q000008:administration & dosage / Q000737:chemistry; D006603:Hexuronic Acids / Q000008:administration & dosage / Q000737:chemistry; D008297:Male; D051379:Mice; D055616:Microtechnology; D011073:Polyamines / Q000008:administration & dosage / Q000737:chemistry; D011137:Polystyrenes / Q000008:administration & dosage / Q000737:chemistry; D011312:Pressure; D013678:Technology, Pharmaceutical
chemical_list: D000464:Alginates; D003692:Delayed-Action Preparations; D003911:Dextrans; D005782:Gels; D006603:Hexuronic Acids; D011073:Polyamines; D011137:Polystyrenes; C015219:fluorescein isothiocyanate dextran; C063994:polyallylamine; C003321:polystyrene sulfonic acid; D020723:Glucuronic Acid; D048271:Chitosan; D016650:Fluorescein-5-isothiocyanate
keywords: chitosan-alginate; layer-by-layer; microgels; polyelectrolyte; pulsed drug delivery