title: High loading efficiency and sustained release of siRNA encapsulated in PLGA nanoparticles: quality by design optimization and characterization.
abstract: Poly(DL-lactide-co-glycolide acid) (PLGA) is an attractive polymer for delivery of biopharmaceuticals owing to its biocompatibility, biodegradability and outstanding controlled release characteristics. The purpose of this study was to understand and define optimal parameters for preparation of small interfering RNA (siRNA)-loaded PLGA nanoparticles by the double emulsion solvent evaporation method and characterize their properties. The experiments were performed according to a 2(5-1) fractional factorial design based on five independent variables: The volume ratio between the inner water phase and the oil phase, the PLGA concentration, the sonication time, the siRNA load and the amount of acetylated bovine serum albumin (Ac-BSA) in the inner water phase added to stabilize the primary emulsion. The effects on the siRNA encapsulation efficiency and the particle size were investigated. The most important factors for obtaining an encapsulation efficiency as high as 70% were the PLGA concentration and the volume ratio whereas the size was mainly affected by the PLGA concentration. The viscosity of the oil phase was increased at high PLGA concentration, which explains the improved encapsulation by stabilization of the primary emulsion and reduction of siRNA leakage to the outer water phase. Addition of Ac-BSA increased the encapsulation efficiency at low PLGA concentrations. The PLGA matrix protected siRNA against nuclease degradation, provided a burst release of surface-localized siRNA followed by a triphasic sustained release for two months. These results enable careful understanding and definition of optimal process parameters for preparation of PLGA nanoparticles encapsulating high amounts of siRNA with immediate and long-term sustained release properties.
authors.affiliation: Department of Pharmaceutics and Analytical Chemistry, University of Copenhagen, Copenhagen Ø, Denmark.
authors.forename: Dongmei
authors.initials: D
authors.lastname: Cun
authors.forename: Ditte Krohn
authors.initials: DK
authors.lastname: Jensen
authors.forename: Morten Jonas
authors.initials: MJ
authors.lastname: Maltesen
authors.forename: Matthew
authors.initials: M
authors.lastname: Bunker
authors.forename: Paul
authors.initials: P
authors.lastname: Whiteside
authors.forename: David
authors.initials: D
authors.lastname: Scurr
authors.forename: Camilla
authors.initials: C
authors.lastname: Foged
authors.forename: Hanne Mørck
authors.initials: HM
authors.lastname: Nielsen
mesh_terms: D000107:Acetylation; D002460:Cell Line; D055598:Chemical Phenomena; D003692:Delayed-Action Preparations / Q000008:administration & dosage / Q000737:chemistry / Q000494:pharmacology; D004337:Drug Carriers / Q000008:administration & dosage* / Q000737:chemistry* / Q000494:pharmacology; D004339:Drug Compounding; D004355:Drug Stability; D004655:Emulsions; D005079:Excipients / Q000737:chemistry; D020868:Gene Silencing / Q000187:drug effects; D006801:Humans; D019344:Lactic Acid / Q000737:chemistry*; D053758:Nanoparticles / Q000737:chemistry* / Q000648:ultrastructure; D036103:Nanotechnology; D010316:Particle Size; D011100:Polyglycolic Acid / Q000737:chemistry*; D000077182:Polylactic Acid-Polyglycolic Acid Copolymer; D034741:RNA, Small Interfering / Q000008:administration & dosage* / Q000737:chemistry / Q000494:pharmacology; D012710:Serum Albumin, Bovine / Q000737:chemistry; D012995:Solubility; D013499:Surface Properties; D014783:Viscosity
chemical_list: D003692:Delayed-Action Preparations; D004337:Drug Carriers; D004655:Emulsions; D005079:Excipients; D034741:RNA, Small Interfering; D000077182:Polylactic Acid-Polyglycolic Acid Copolymer; D011100:Polyglycolic Acid; D012710:Serum Albumin, Bovine; D019344:Lactic Acid