title: Atomic Force Microscopy of spermidine-induced DNA condensates on silicon surfaces.
abstract: In the present work, we show that oxidized silicon may be successfully used to image multivalent cation-induced DNA condensates under the Atomic Force Microscope (AFM). The images thus obtained are good enough, allowing us to distinguish between different condensate forms and to perform nanometer-sized measurements. Qualitative results previously obtained using mica as a substrate are recovered here. We additionally show that the interactions between the cation spermidine (the condensing agent) and the DNA molecules are not significantly disturbed by the silicon surface, since the phase behavior of an ensemble of DNA molecules deposited on the silicon substrate as a function of the cation concentration is very similar to that found in solution.
authors.affiliation: Departamento de Física, Universidade Federal de Viçosa, CEP 36570-000, Viçosa, Minas Gerais, Brazil.
authors.forename: I S S
authors.initials: IS
authors.lastname: Carrasco
authors.forename: F M
authors.initials: FM
authors.lastname: Bastos
authors.forename: M L
authors.initials: ML
authors.lastname: Munford
authors.forename: E B
authors.initials: EB
authors.lastname: Ramos
authors.forename: M S
authors.initials: MS
authors.lastname: Rocha
mesh_terms: D004247:DNA / Q000737:chemistry*; D018625:Microscopy, Atomic Force / Q000379:methods*; D010710:Phosphates / Q000737:chemistry; D012825:Silicon / Q000737:chemistry*; D013095:Spermidine / Q000031:analogs & derivatives* / Q000737:chemistry; D013499:Surface Properties
chemical_list: D010710:Phosphates; C007545:DNA-spermidine; D004247:DNA; D013095:Spermidine; D012825:Silicon