title: The fractal structure of polycation-DNA complexes.
abstract: We used static light scattering to obtain new measurements on the internal structure of aggregated non-viral gene-delivery particles in colloidal suspension. The vector particles are prepared by charge neutralization of plasmid DNA either by poly-L-lysine or by a Lipofectin/integrin-targeting peptide. We use established theories of the stability of colloidal particles and fractal concepts to explain the aggregation processes and demonstrate the existence of a new property (fractal dimension) of the aggregated vector particles. Aggregation is shown to produce particles with fractal dimensions in the range between 1.8 and 2.4; the former suggests a loose three-dimensional structure and the latter characterizes an aggregation process that leads to the formation of particles with tightly packed structures. We show that the fractal dimension of the vector particles is sensitive to changes in physicochemical conditions (ionic strength) of the buffer solution and propose that fractal dimension may provide a useful means of monitoring the physical state of non-viral delivery-vector particles during preparation and storage.
authors.affiliation: Department of Biochemical Engineering, University College London, Torrington Place, London WC1E 7JE, U.K.
authors.forename: Supti
authors.initials: S
authors.lastname: Sarkar
authors.forename: Li Kim
authors.initials: LK
authors.lastname: Lee
authors.forename: Stephen L
authors.initials: SL
authors.lastname: Hart
authors.forename: Helen C
authors.initials: HC
authors.lastname: Hailes
authors.forename: Susana M
authors.initials: SM
authors.lastname: Levy
authors.forename: Alethea
authors.initials: A
authors.lastname: Tabor
authors.forename: Parviz Ayazi
authors.initials: PA
authors.lastname: Shamlou
mesh_terms: D002412:Cations / Q000737:chemistry* / Q000378:metabolism; D004247:DNA / Q000737:chemistry* / Q000378:metabolism; D017709:Fractals; D005822:Genetic Vectors / Q000737:chemistry; D006863:Hydrogen-Ion Concentration; D010957:Plasmids / Q000737:chemistry; D011108:Polymers / Q000737:chemistry*; D012996:Solutions / Q000737:chemistry
chemical_list: D002412:Cations; D011108:Polymers; D012996:Solutions; D004247:DNA