title: Biophysical characterization of an integrin-targeted lipopolyplex gene delivery vector.
abstract: Nonviral gene delivery vectors now show good therapeutic potential: however, detailed characterization of the composition and macromolecular organization of such particles remains a challenge. This paper describes experiments to elucidate the structure of a ternary, targeted, lipopolyplex synthetic vector, the LID complex. This consists of a lipid component, Lipofectin (L) (1:1 DOTMA:DOPE), plasmid DNA (D), and a dual-function, cationic peptide component (I) containing DNA condensation and integrin-targeting sequences. Fluorophore-labeled lipid, peptide, and DNA components were used to formulate the vector, and the stoichiometry of the particles was established by fluorescence correlation spectroscopy (FCS). The size of the complex was measured by FCS, and the sizes of LID, L, LD, and ID complexes were measured by dynamic light scattering (DLS). Fluorescence quenching experiments and freeze-fracture electron microscopy were then used to demonstrate the arrangement of the lipid, peptide, and DNA components within the complex. These experiments showed that the cationic portion of the peptide, I, interacts with the plasmid DNA, resulting in a tightly condensed DNA-peptide inner core; this is surrounded by a disordered lipid layer, from which the integrin-targeting sequence of the peptide partially protrudes.
authors.affiliation: Department of Chemistry, Christopher Ingold Laboratories, University College London, United Kingdom.
authors.forename: M Firouz Mohd
authors.initials: MF
authors.lastname: Mustapa
authors.forename: Paul C
authors.initials: PC
authors.lastname: Bell
authors.forename: Christopher A
authors.initials: CA
authors.lastname: Hurley
authors.forename: Alastair
authors.initials: A
authors.lastname: Nicol
authors.forename: Erwann
authors.initials: E
authors.lastname: Guénin
authors.forename: Supti
authors.initials: S
authors.lastname: Sarkar
authors.forename: Michele J
authors.initials: MJ
authors.lastname: Writer
authors.forename: Susie E
authors.initials: SE
authors.lastname: Barker
authors.forename: John B
authors.initials: JB
authors.lastname: Wong
authors.forename: Michael A
authors.initials: MA
authors.lastname: Pilkington-Miksa
authors.forename: Brigitte
authors.initials: B
authors.lastname: Papahadjopoulos-Sternberg
authors.forename: Parviz Ayazi
authors.initials: PA
authors.lastname: Shamlou
authors.forename: Helen C
authors.initials: HC
authors.lastname: Hailes
authors.forename: Stephen L
authors.initials: SL
authors.lastname: Hart
authors.forename: Daniel
authors.initials: D
authors.lastname: Zicha
authors.forename: Alethea B
authors.initials: AB
authors.lastname: Tabor
mesh_terms: D055592:Biophysical Phenomena; D001703:Biophysics; D004247:DNA / Q000737:chemistry; D004058:Diffusion; D005614:Freeze Fracturing; D005822:Genetic Vectors; D016023:Integrins; D008027:Light; D008081:Liposomes / Q000138:chemical synthesis; D008854:Microscopy, Electron; D010714:Phosphatidylethanolamines / Q000737:chemistry; D000644:Quaternary Ammonium Compounds / Q000737:chemistry; D012542:Scattering, Radiation; D013050:Spectrometry, Fluorescence
chemical_list: D016023:Integrins; D008081:Liposomes; D010714:Phosphatidylethanolamines; D000644:Quaternary Ammonium Compounds; C054005:N-(1-(2,3-dioleyloxy)propyl)-N,N,N-trimethylammonium; C094877:dioleoyl phosphatidylethanolamine; C020888:1,2-dielaidoylphosphatidylethanolamine; D004247:DNA