title: Molecular Combing of λ-DNA using Self-Propelled Water Droplets on Wettability Gradient Surfaces.
abstract: Surface wettability gradients were used to elongate and align double stranded λ-DNA. Gradients were prepared by vapor phase deposition of octyltrichlorosilane (C8-silane) and fluorinated octyltrichlorosilane (F-silane) precursors. Gradient formation was confirmed by water contact angle and ellipsometric film thickness measurements. Placement of a droplet of aqueous DNA solution on the hydrophobic end of each gradient led to spontaneous motion of the droplet toward the hydrophilic end and deposition of the DNA. Fluorescence imaging of surface-adsorbed YOYO-1 labeled DNA molecules revealed that they are elongated and aligned perpendicular to the droplet-surface contact line at all positions along the gradient, consistent with a dominant role played by surface tension forces in elongating the DNA. The density of adsorbed DNA was found to be greatest on the C8-silane gradient at its hydrophobic end. DNA density decreased toward the hydrophilic end, while the length of the elongated DNA was less dependent on position. The elongation of DNA molecules by spontaneous droplet motion on chemical gradient surfaces has possible applications in DNA barcoding and studies of DNA-protein interactions.
authors.affiliation: Department of Chemistry, Kansas State University , Manhattan, Kansas 66506-0401, United States.
authors.forename: Dipak
authors.initials: D
authors.lastname: Giri
authors.affiliation: Department of Chemistry, Kansas State University , Manhattan, Kansas 66506-0401, United States.
authors.forename: Zi
authors.initials: Z
authors.lastname: Li
authors.affiliation: Department of Chemistry, Virginia Commonwealth University , Richmond, Virginia 23284-2006, United States.
authors.forename: Kayesh M
authors.initials: KM
authors.lastname: Ashraf
authors.affiliation: Department of Chemistry, Virginia Commonwealth University , Richmond, Virginia 23284-2006, United States.
authors.forename: Maryanne M
authors.initials: MM
authors.lastname: Collinson
authors.affiliation: Department of Chemistry, Kansas State University , Manhattan, Kansas 66506-0401, United States.
authors.forename: Daniel A
authors.initials: DA
authors.lastname: Higgins
mesh_terms: D004247:DNA; D057927:Hydrophobic and Hydrophilic Interactions; D013500:Surface Tension; D014867:Water; D017155:Wettability
chemical_list: D014867:Water; D004247:DNA
keywords: fluorescence imaging; liquid transport on gradients; organosilanes; surface immobilization of biomolecules; vapor phase deposition; water contact angles