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Vanderlinden W.,Laboratory of Photochemistry and Spectroscopy | De Feyter S.,Laboratory of Photochemistry and Spectroscopy
Nanoscale | Year: 2013

We have used scanning force microscopy (SFM) to elucidate the dynamic behavior of open (torsionally unconstrained) circular and long linear DNA molecules during the relaxation process following adsorption onto mica. We find that bending stress and excluded volume effects drive the conformational equilibration via segmental out-of-plane dynamics. © 2013 The Royal Society of Chemistry. Source

Vanderlinden W.,Laboratory of Photochemistry and Spectroscopy | Blunt M.,Laboratory of Photochemistry and Spectroscopy | David C.C.,Laboratory of Photochemistry and Spectroscopy | Moucheron C.,Organic Avenue | And 2 more authors.
Journal of the American Chemical Society | Year: 2012

We used scanning force microscopy (SFM) to study the binding and excited state reactions of the intercalating photoreagent Ru[(TAP) 2PHEHAT] 2+ (TAP = 1,4,5,8-tetraazaphenanthrene; PHEHAT = 1,10- phenanthrolino[5,6-b]1,4,5,8,9,12-hexaazatriphenylene) with DNA. In the ground state, this ruthenium complex combines a strong intercalative binding mode via the PHEHAT ligand, with TAP-mediated hydrogen bonding capabilities. After visible irradiation, SFM imaging of the photoproducts revealed both the structural implications of photocleavages and photoadduct formation. It is found that the rate of photocleaving is strongly increased when the complex can interact with DNA via hydrogen bonding. We demonstrated that the photoadduct increases DNA rigidity, and that the photo-biadduct can crosslink two separate DNA segments in supercoiled DNA. These mechanical and topological effects might have important implications in future therapeutic applications of this type of compounds. © 2012 American Chemical Society. Source

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