title: Preparation and characterization of poly (D,L-lactide-co-glycolide) microspheres for controlled release of poly(L-lysine) complexed plasmid DNA.
abstract: OBJECTIVE
  To produce and characterize controlled release formulations of plasmid DNA (pDNA) loaded in poly (D,L-lactide-co-glycolide) (PLGA) microspheres both in free form and as a complex with poly (L-lysine).
  
  
  METHODS
  Poly (L-lysine) (PLL) was used to form pDNA/PLL complexes with complexation ratio of 1:0.125 and 1:0.333 w/w to enhance the stability of pDNA during microsphere preparation and protect pDNA from nuclease attack. pDNA structure, particle size, zeta potential, drug loading, in vitro release properties, and protection from DNase I were studied.
  
  
  RESULTS
  The microspheres were found to be spherical with average particle size of 3.1-3.5 microm. Drug loading of 0.6% was targeted. Incorporation efficiencies of 35.1% and 29.4-30.6% were obtained for pDNA and pDNA/PLL loaded microspheres respectively. Overall, pDNA release kinetics following the initial burst did not correlate with blank microsphere polymer degradation profile suggesting that pDNA release is convective diffusion controlled. The percentage of supercoiled pDNA in the pDNA and pDNA/PLL loaded microspheres was 16.6 % and 76.7-85.6% respectively. Unencapsulated pDNA and pDNA/PLL degraded completely within 30 minutes upon the addition of DNase I. Encapsulation of DNA/PLL in PLGA microspheres protected pDNA from enzymatic degradation.
  
  
  CONCLUSIONS
  The results show that using a novel process, pDNA can be stabilized and encapsulated in PLGA microspheres to protect pDNA from enzymatic degradation.
authors.affiliation: University of Kentucky, College of Pharmacy, Faculty of Pharmaceutical Sciences, Lexington 40536, USA.
authors.forename: Y
authors.initials: Y
authors.lastname: Capan
authors.forename: B H
authors.initials: BH
authors.lastname: Woo
authors.forename: S
authors.initials: S
authors.lastname: Gebrekidan
authors.forename: S
authors.initials: S
authors.lastname: Ahmed
authors.forename: P P
authors.initials: PP
authors.lastname: DeLuca
mesh_terms: D001672:Biocompatible Materials / Q000008:administration & dosage / Q000138:chemical synthesis*; D004247:DNA / Q000008:administration & dosage / Q000138:chemical synthesis* / Q000378:metabolism; D003692:Delayed-Action Preparations; D003850:Deoxyribonuclease I / Q000378:metabolism / Q000494:pharmacology; D004339:Drug Compounding; D019344:Lactic Acid / Q000008:administration & dosage / Q000138:chemical synthesis*; D008855:Microscopy, Electron, Scanning; D008863:Microspheres; D010316:Particle Size; D010957:Plasmids / Q000008:administration & dosage / Q000138:chemical synthesis* / Q000648:ultrastructure; D011100:Polyglycolic Acid / Q000008:administration & dosage / Q000138:chemical synthesis*; D000077182:Polylactic Acid-Polyglycolic Acid Copolymer; D011107:Polylysine / Q000008:administration & dosage / Q000737:chemistry*; D011108:Polymers / Q000008:administration & dosage / Q000138:chemical synthesis*; D013499:Surface Properties
chemical_list: D001672:Biocompatible Materials; D003692:Delayed-Action Preparations; D011108:Polymers; D000077182:Polylactic Acid-Polyglycolic Acid Copolymer; D011107:Polylysine; D011100:Polyglycolic Acid; D019344:Lactic Acid; D004247:DNA; D003850:Deoxyribonuclease I