title: DNA-poly(diallyldimethylammonium chloride) complexation and transfection efficiency.
abstract: The present work assesses the influence of the cationic charge density (CD) and the cationic valence of poly(diallyldimethylammonium chloride) (pDADMAC) on the DNA compaction and subsequent transfection. Four homopolymers (CD = 1, with different valences) and one copolymer, poly(acrylamide-co-diallyldimethylammonium chloride) (coDADMAC) (CD < 1, equivalent in valence to one of the homopolymers), were studied. The characterization of the DNA-pDADMAC complexes (polyplexes) as a function of the polycation nitrogen to DNA phosphate molar ratios, N/P, was done by means of conductometry, electrophoretic mobility (zeta-potential), dynamic light scattering (DLS), isothermal titration calorimetry (ITC), atomic force microscopy (AFM), and beta-galactosidase (ONPG) and luciferase expression assays at 25 degrees C and physiological pH. In general, all polyplexes rendered compact and stable structures (R(H) approximately 100 nm) with positive surface charges ( approximately 11 mV) but low transfection efficiencies. As revealed by ITC, the DNA-pDADMAC complexation was characterized by a high binding affinity, the process being entropically driven. In particular, two characteristic ratios ((N/P)c and (N/P)*) were detected. Conductometry and ITC data demonstrated that the DNA compaction ratio, (N/P)c, was mainly governed by CD. Meanwhile the ratio from which the polyplex size remained constant, (N/P)*, was found to be valence-dependent as revealed by DLS. On the other hand, the low transfer rate of the polyplexes appeared to be correlated with the high binding affinity observed throughout the complexation process and with a core-shell structure the complexes presumably adopt.
authors.affiliation: Grupo de Nanomateriales y Materia Blanda, Departamento de Física de la Materia Condensada, Facultad de Física, Universidad de Santiago de Compostela, E-15782 Santiago de Compostela, Spain. manuel_alatorre@yahoo.com.mx
authors.forename: Manuel
authors.initials: M
authors.lastname: Alatorre-Meda
authors.forename: Pablo
authors.initials: P
authors.lastname: Taboada
authors.forename: Barbara
authors.initials: B
authors.lastname: Krajewska
authors.forename: Markus
authors.initials: M
authors.lastname: Willemeit
authors.forename: Alexander
authors.initials: A
authors.lastname: Deml
authors.forename: Roland
authors.initials: R
authors.lastname: Klösel
authors.forename: Julio R
authors.initials: JR
authors.lastname: Rodríguez
mesh_terms: D002151:Calorimetry; D004247:DNA / Q000737:chemistry*; D008156:Luciferases / Q000235:genetics / Q000378:metabolism; D018625:Microscopy, Atomic Force; D011095:Polyethylenes / Q000737:chemistry*; D000644:Quaternary Ammonium Compounds / Q000737:chemistry*; D013816:Thermodynamics; D014162:Transfection; D001616:beta-Galactosidase / Q000235:genetics / Q000378:metabolism
chemical_list: D011095:Polyethylenes; D000644:Quaternary Ammonium Compounds; C041004:poly-N,N-dimethyl-N,N-diallylammonium chloride; D004247:DNA; D008156:Luciferases; D001616:beta-Galactosidase