51ÁÔÆæÈë¿Ú

Abstract:

Future lipid membrane-associated DNA nanostructures are expected to find applications ranging from synthetic biology to nanomedicine. Here we have designed and synthesized DNA tiles and modified them by amphiphilic covalent moieties. dod-DEG groups, which consist of a hydrophilic diethylene glycol (DEG) and a hydrophobic dodecyl group, are introduced at the phosphate backbone to create amphiphilic DNA strands which are subsequently introduced into one face of DNA tiles. In this way the tile becomes able to stably bind to lipid membranes by insertion of the hydrophobic groups inside the bilayer core. The functionalized tiles do not aggregate in solution. Our results show that these amphiphilic DNA tiles can bind and assemble into 2D lattices on both gel and fluid lipid bilayers. The binding of the DNA structures to membranes is dependent on the lipid phase of the membrane, the concentration of Mg2+ cation, the length of the amphiphilic modifications to the DNA as well as on the density of the modifications within the tile. Atomic force microscopy–based force spectroscopy is used to investigate the effect of the inserted DNA tiles on the mechanical properties of the lipid membranes. The results indicate that the insertion of DNA tiles produces an approx. 20% increase of the bilayer breakthrough force.

Abstract:

We demonstrate, for the first time, confinement of the orientation of graphitic micro-flakes to a well-defined plane in solution by applying two perpendicular fields: a vertical static magnetic field and a horizontal time-varying electric field.

Abstract:

Quantification of DNA damage is an important technique for medical physics, for example to assess damage caused by the quinolone antibiotics, or to examine the effects of novel cancer treatments such as low-temperature plasma therapy on healthy or tumorous cells. Existing damage quantification techniques such as the alkaline comet assay [1] are often subjective in their results, especially at higher damage levels. Methods using immunofluorescence [2] often lose information due to the three dimensional nature of the cell.