title: Preparation and characterization of negatively charged poly(lactic-co-glycolic acid) microspheres.
abstract: Negatively charged poly(lactic-co-glycolic acid) (PLGA) microspheres encapsulated with hydrophilic drugs have been successfully prepared by a solid-in-oil-in-water (s/o/w) solvent evaporation method in the presence of anionic surfactants, sodium dodecyl sulfate (SDS), and dioctyl sodium sulfosuccinate (DSS), and nonionic surfactant polyvinyl alcohol (PVA). The effects of microencapsulation methods, surfactants types, and surfactant concentrations on the properties of microspheres were studied. Amoxicillin (AMX) was chosen as a hydrophilic model drug, and its encapsulation efficiency (EE) and in vitro release profiles were measured. The s/o/w method achieved higher EE of 40% in PLGA microspheres using surfactant SDS compared with the conventional water-in-oil-in-water (w/o/w) method (about 2%). Triphasic release profiles were observed for all PLGA microspheres (s/o/w) with slight drug burst, a slow diffusion-controlled release within the period of about 7 days and followed by the degradation-controlled sustained release for further 30 days. Smaller particle size and surface charge were achieved for s/o/w method than w/o/w method using the same anionic surfactants, and smooth surface and less porous interior matrix. The s/o/w method effectively encapsulated AMX into anionic PLGA microspheres using anionic surfactants, and these negatively charged PLGA microspheres represented an attractive approach for the controlled release of hydrophilic drugs.
authors.affiliation: Department of Materials, University of Oxford, Parks Road, Oxford OX1 3PH, UK. qingguo.xu@materials.ox.ac.uk
authors.forename: Qingguo
authors.initials: Q
authors.lastname: Xu
authors.forename: Alison
authors.initials: A
authors.lastname: Crossley
authors.forename: Jan
authors.initials: J
authors.lastname: Czernuszka
mesh_terms: D000658:Amoxicillin / Q000737:chemistry*; D000900:Anti-Bacterial Agents / Q000737:chemistry*; D004337:Drug Carriers / Q000737:chemistry*; D004338:Drug Combinations; D004339:Drug Compounding / Q000379:methods*; D007510:Isatin / Q000031:analogs & derivatives / Q000737:chemistry; D019344:Lactic Acid / Q000737:chemistry*; D008855:Microscopy, Electron, Scanning; D008863:Microspheres; D010316:Particle Size; D011100:Polyglycolic Acid / Q000737:chemistry*; D000077182:Polylactic Acid-Polyglycolic Acid Copolymer; D011142:Polyvinyl Alcohol / Q000737:chemistry; D011725:Pyridines / Q000737:chemistry; D012967:Sodium Dodecyl Sulfate / Q000737:chemistry; D013052:Spectrometry, X-Ray Emission; D055672:Static Electricity; D013386:Succinates / Q000737:chemistry; D013501:Surface-Active Agents / Q000737:chemistry; D044366:Transition Temperature
chemical_list: D000900:Anti-Bacterial Agents; D004337:Drug Carriers; D004338:Drug Combinations; D011725:Pyridines; D013386:Succinates; D013501:Surface-Active Agents; C001526:laxagetten 4,4'-diacetoxydiphenylpyridylemethane; D000077182:Polylactic Acid-Polyglycolic Acid Copolymer; D011100:Polyglycolic Acid; D019344:Lactic Acid; D012967:Sodium Dodecyl Sulfate; D000658:Amoxicillin; D007510:Isatin; D011142:Polyvinyl Alcohol