Reversible Structural Switching of a DNA−DDAB Film

Abstract

We describe the novel structure and behavior of a DNA-DDAB complex film cast from an organic solvent which exhibits a structural switching transition as it is dried or wetted with water. The film can be easily prepared by forming a complex between the negatively charged phosphate groups of DNA and the positively charged headgroup of the surfactant DDAB. This complex is then purified, dried, dissolved in isopropanol and cast onto a glass slide to form a self-standing film by means of slow evaporation. While the structure of the dried film was found to be composed of single-stranded DNA and a monolayer of DDAB, upon hydration of the film the structure switched to double stranded DNA complexed to a bilayer of DDAB. We expect that this phenomenon would serve as a useful model for the design of new responsive materials and programmable self-assembly.

Dispersions based on noble metal nanoparticles-DNA conjugates

“…Highly ordered thin films of DNA-based assemblies have been previously prepared by a variety of methods including spin coating, simple casting, and the Langmuir-Blodgett technique [101]. Furthermore, the hydrophobicity of DNA-surfactant complexes provides a possibility for the construction of heterogeneous functioned surfaces.…”

Surface Engineering Using Peptide Amphiphiles

“…In order for such practical applications to further advance the precise understanding of surface engineering principles, stability of assembled structures, biodistribution, and the cell-material interface created by peptide-based materials and living systems will be very important. Two key aspects of PAs' capabilities to control biological systems will be to control protein and nucleic acid function within and outside the cell 103,166,[189][190][191][192][193][194] and to three-dimensionally mimic the naturally occurring extracellular matrices 7,11,73,115,118,[195][196][197] if these two functions are combined and well defined, then some of the undefined components pertaining to biomedical applications, such as stem cell tissue engineering and targeted drug delivery, can incorporate more quantitative subcomponents. …”

Spontaneous growth of self-relief wrinkles in freely floating lipid-based nanomembranes, formed on a reactive bath of polyoxometalate aqueous solution

“…2D structures of functional organic/inorganic nanocomposite materials and especially, freestanding nanomembranes of these structures have attracted much attention during the recent decade, owing to their potential applications in domains as diverse as medicine, bioengineering, and nanotechnologies [1][2][3][4][5][6][7][8]. For water-insoluble molecules, there are fabrication methods based on the crosslinking of Langmuir films, and the layer-by-layer (LbL) deposition followed by a lifting off step, which have produced free standing membranes of both organic and composite materials [1,[9][10][11][12].…”

“…Of particular interest, these experiments relate to nanomembranes of dimethyl-dioctadecyl-ammonuim bromide (DDAB), a cationic double-chained lipid surfactant, and of silicotungstate, a Keggin polyoxometalate nanosize anions [3][4][5][6][7][23][24][25][26][27][28]. These two components are two basic and potential building units for highly functional structures in materials science and bioengineering [3][4][5][6][7][23][24][25][26][27][28].…”

“…These two components are two basic and potential building units for highly functional structures in materials science and bioengineering [3][4][5][6][7][23][24][25][26][27][28]. Whereas DDAB is recurrently used as model lipid for biomembranes and gene transfection [6,[23][24][25], silicotungstate acid (STA) anions have unique combination of physical and chemical properties that are widely used in photocatalysis and biochemistry, as well as in medicine for their antiviral and antitumoral activity [5][6][7][26][27][28]. The membranes are formed dynamically by the reactive wetting of droplets of (DDAB/chloroform) solutions, which is mediated by STA anions contained in the aqueous sub-phase.…”