The fractal structure of polycation-DNA complexes.
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.
Sarkar
Supti
S
Department of Biochemical Engineering, University College London, Torrington Place, London WC1E 7JE, U.K.
Lee
Li Kim
LK
Hart
Stephen L
SL
Hailes
Helen C
HC
Levy
Susana M
SM
Tabor
Alethea
A
Shamlou
Parviz Ayazi
PA
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
D002412:Cations; D011108:Polymers; D012996:Solutions; D004247:DNA