title: SANS study of the interactions among DNA, a cationic surfactant, and polystyrene latex particles.
abstract: The compaction of DNA by a cationic surfactant both in the bulk and adsorbed on the surface of latex particles was followed for the first time by SANS. In the bulk, a decrease in the overall size of the DNA coil in the presence of the cationic surfactant was observed at a negative-to-positive charge ratio far below the phase separation region, at a negative-to-positive charge ratio of 18. Additionally, large surfactant aggregates seem to form within the DNA-surfactant complex. On the other hand, DNA adsorbs onto the surface of latex particles, forming a thick layer, as evidenced by the fitting of the SANS data to a core-shell form factor. Addition of a cationic surfactant to the DNA-coated latex particles at a negative-to-positive charge ratio of 38 induces a slight decrease in the size of the particle layer, where the cationic surfactant is evenly distributed within the adsorbed layer. A further decrease of the negative-to-positive charge ratio to 18 induces a dramatic change in the SANS data that suggests significant compaction of the adsorbed layer and the formation of large surfactant aggregates, similar to those detected in the bulk.
authors.affiliation: Center for Chemistry and Chemical Engineering, Physical Chemistry 1, University of Lund, P.O. Box 124, SE-221 00 Lund, Sweden. Marite.Cardenas@fkem1.le.se
authors.forename: Marité
authors.initials: M
authors.lastname: Cárdenas
authors.forename: Cécile A
authors.initials: CA
authors.lastname: Dreiss
authors.forename: Tommy
authors.initials: T
authors.lastname: Nylander
authors.forename: Chau P
authors.initials: CP
authors.lastname: Chan
authors.forename: Terence
authors.initials: T
authors.lastname: Cosgrove
authors.forename: Björn
authors.initials: B
authors.lastname: Lindman
mesh_terms: D000327:Adsorption; D002412:Cations; D004247:DNA / Q000737:chemistry*; D057927:Hydrophobic and Hydrophilic Interactions; D007840:Latex / Q000737:chemistry*; D008863:Microspheres; D033363:Neutron Diffraction / Q000379:methods*; D009690:Nucleic Acid Conformation; D010316:Particle Size; D011137:Polystyrenes / Q000737:chemistry*; D012542:Scattering, Radiation; D013499:Surface Properties; D013501:Surface-Active Agents / Q000737:chemistry*
chemical_list: D002412:Cations; D007840:Latex; D011137:Polystyrenes; D013501:Surface-Active Agents; D004247:DNA