title: Novel biodegradable and pH-sensitive poly(ester amide) microspheres for oral insulin delivery.
abstract: Biodegradable and pH-sensitive PEAs based on dual amino acids are designed, synthesized, and characterized. Insulin can be loaded into the PEA microspheres by a solid-in-oil-in-oil technique with high encapsulation efficiency. The feasibility of PEA microspheres as oral insulin delivery carriers is evaluated in vitro and in vivo. The hydrophobic leucine groups on PEA seem to play an important role in the pH-dependent release mechanism and cytotoxicity of PEA microspheres. Oral administration of insulin-loaded PEA microspheres to streptozotocin-induced diabetic rats at 60 IU kg(-1)  is able to reduce fasting plasma glucose levels to 49.4%. These results indicate that PEA microspheres are potential new vehicles for insulin oral delivery.
authors.affiliation: Key Laboratory of Polymer Ecomaterials, Changchun Institute of Applied Chemistry, Chinese Academy of Sciences, Changchun 130022, China.
authors.forename: Pan
authors.initials: P
authors.lastname: He
authors.forename: Zhaohui
authors.initials: Z
authors.lastname: Tang
authors.forename: Lin
authors.initials: L
authors.lastname: Lin
authors.forename: Mingxiao
authors.initials: M
authors.lastname: Deng
authors.forename: Xuan
authors.initials: X
authors.lastname: Pang
authors.forename: Xiuli
authors.initials: X
authors.lastname: Zhuang
authors.forename: Xuesi
authors.initials: X
authors.lastname: Chen
mesh_terms: D000284:Administration, Oral; D000818:Animals; D001672:Biocompatible Materials; D001786:Blood Glucose / Q000032:analysis; D002460:Cell Line; D002470:Cell Survival / Q000187:drug effects; D003921:Diabetes Mellitus, Experimental / Q000097:blood / Q000188:drug therapy*; D004337:Drug Carriers; D004339:Drug Compounding; D006863:Hydrogen-Ion Concentration; D057927:Hydrophobic and Hydrophilic Interactions; D007004:Hypoglycemic Agents / Q000008:administration & dosage* / Q000737:chemistry / Q000493:pharmacokinetics; D007328:Insulin / Q000008:administration & dosage* / Q000737:chemistry / Q000493:pharmacokinetics; D009682:Magnetic Resonance Spectroscopy; D008297:Male; D008855:Microscopy, Electron, Scanning; D008863:Microspheres; D010316:Particle Size; D011091:Polyesters / Q000138:chemical synthesis* / Q000737:chemistry; D051381:Rats; D017208:Rats, Wistar
chemical_list: D001672:Biocompatible Materials; D001786:Blood Glucose; D004337:Drug Carriers; D007004:Hypoglycemic Agents; D007328:Insulin; D011091:Polyesters