title: Evaluation of different buffers on plasmid DNA encapsulation into PLGA microparticles.
abstract: Double emulsion solvent evaporation is a widely used method to prepare poly(dl-lactide-co-glycolide) (PLGA) microparticles encapsulating plasmid DNA. There are inherent problems associated with preparing plasmid DNA in this form, in particular the DNA is liable to degrade during manufacture and the resulting powder has low encapsulation efficiencies. This study compares the use of two buffers, 0.1M NaHCO(3) and 0.07M Na(2)HPO(4) and the effect these have on the encapsulation efficiency and other critical parameters associated with these encapsulated DNA materials. Both buffers preserved the conformation of the original plasmid DNA during the homogenization process, but those made with 0.07M Na(2)HPO(4) had higher encapsulation efficiencies, as well as smaller diameters, compared with those made with 0.1M NaHCO(3) (encapsulation efficiencies of 40.72-45.65%, and mean volume diameters of 2.96-4.45microm). Buffers with a range of pH from 5 to 12 were investigated, and it was demonstrated that pH 9 was the point at which the highest amount of supercoiled DNA was balanced with the highest encapsulation efficiency. To simulate in vitro release, it was shown that microparticles made with 0.07M Na(2)HPO(4) had lower DNA release rates than those made with 0.1M NaHCO(3). These results demonstrate that the use of different buffers can aid in retaining the conformation of plasmid DNA, and can also modulate the amount of DNA encapsulated and the release profiles of microparticles.
authors.affiliation: Centre for Drug Delivery Research, The School of Pharmacy, University of London, 29/39 Brunswick Square, London WC1N 1AX, United Kingdom.
authors.forename: Man Tsuey
authors.initials: MT
authors.lastname: Tse
authors.forename: Chris
authors.initials: C
authors.lastname: Blatchford
authors.forename: H
authors.initials: H
authors.lastname: Oya Alpar
mesh_terms: D002021:Buffers; D002626:Chemistry, Pharmaceutical; D004247:DNA / Q000008:administration & dosage / Q000737:chemistry*; D004337:Drug Carriers / Q000737:chemistry*; D004339:Drug Compounding; D006863:Hydrogen-Ion Concentration; D019344:Lactic Acid / Q000008:administration & dosage / Q000737:chemistry*; D008855:Microscopy, Electron, Scanning; D009690:Nucleic Acid Conformation; D010316:Particle Size; D010710:Phosphates / Q000737:chemistry; D010957:Plasmids; D011100:Polyglycolic Acid / Q000008:administration & dosage / Q000737:chemistry*; D000077182:Polylactic Acid-Polyglycolic Acid Copolymer; D017693:Sodium Bicarbonate / Q000737:chemistry
chemical_list: D002021:Buffers; D004337:Drug Carriers; D010710:Phosphates; D000077182:Polylactic Acid-Polyglycolic Acid Copolymer; D011100:Polyglycolic Acid; D019344:Lactic Acid; D017693:Sodium Bicarbonate; D004247:DNA; C018279:sodium phosphate