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“We present experimental data on the electrical and optical behavior of circular and linear plasmid DNA molecules click here embedded in an aqueous matrix. From the electrical point of view, the results indicate that the presence of water is essential when the

DNA concentration is not sufficient to ensure conduction patterns, consistent with the conduction mechanisms proposed for DNA molecules. In fact, as droplets are layered on the substrate, a nonlinear behavior of the current-voltage curves is observed; when water evaporates, the conductivity decreases to a very low value that resembles the high resistivity of the substrate. As more droplets are added, the current increases giving higher conductivity, as expected, since more molecules participate into the conduction process. The conduction behavior of DNA could be due to a tunneling transport of charges inside the molecule, the tunneling barrier being the adenine-thymine bridge between

consecutive guanine-cytosine base pairs. A hopping channel, activated by the water surrounding the molecules, could act as an additional mechanism between different molecules. Optical reflectance measurements, performed in the wavelength range 230-450 nm on dried samples, obtained by complete evaporation of the aqueous matrix containing plasmid DNA under UV-VIS light, reveal absorption in the wavelength range 230-300 nm, typical ON-01910 supplier of DNA-based materials. Moreover, in correspondence of the absorption region, the higher the DNA concentration, the higher the reflectance reduction. This suggests that the DNA concentration strongly influences the spectral behavior of biological layers. Finally, we present preliminary results exploiting the possibility GSK2118436 supplier to control the

morphological and optical features of DNA layers by means of proper lighting procedures. Both electrical and optical measurements indicate that the DNA concentration is a crucial parameter for technical applications. The results reported here provide a contribution for the possible use of DNA molecules in the field of electro-optical biosensors. (C) 2011 American Institute of Physics. [doi:10.1063/1.3563064]“
“Burkholderia cepacia complex bacteria are opportunistic pathogens that cause respiratory tract infections in susceptible patients, mainly people with cystic fibrosis. There is convincing evidence that B. cepacia complex bacteria can form biofilms, not only on abiotic surfaces (e.g., glass and plastics), but also on biotic surfaces such as epithelial cells, leading to the suggestion that biofilm formation plays a key role in persistent infection of cystic fibrosis lungs. This article presents an overview of the molecular mechanisms involved in B. cepacla complex biofilm formation, the increased resistance of sessile B. cepacia complex cells and the role of quorum sensing in B. cepacia complex biofilm formation.