The five Ws (and one H) of super-hydrophobic surfaces in medicine

6Super-hydrophobic surfaces (SHSs) are bio-inspired, artificial microfabricated interfaces, in which a pattern of cylindrical micropillars is modified to incorporate details at the nanoscale. For those systems, the integration of different scales translates into superior properties, including the ability of manipulating biological solutions. The five Ws, five Ws and one H or the six Ws (6W), are questions, whose answers are considered basic in information-gathering. They constitute a formula for getting the complete story on a subject. According to the principle of the six Ws, a report can only be considered complete if it answers these questions starting with an interrogative word: who, why, what, where, when, how. Each question should have a factual answer. In what follows, SHSs and some of the most promising applications thereof are reviewed following the scheme of the 6W. We will show how these surfaces can be integrated into bio-photonic devices for the identification and detection of a single molecule. We will describe how SHSs and nanoporous silicon matrices can be combined to yield devices with the capability of harvesting small molecules, where the cut-off size can be adequately controlled. We will describe how this concept is utilized for obtaining a direct TEM image of a DNA molecule. © 2014 by the authors; licensee MDPI, Basel, Switzerland.openopenGentile F.; Coluccio M.L.; Limongi T.; Perozziello G.; Candeloro P.; Di Fabrizio E.Gentile, F.; Coluccio, M. L.; Limongi, T.; Perozziello, G.; Candeloro, P.; Di Fabrizio, E

Thermal transport in DNA

Thermal transport in DNA is systematically studied to facilitate the development of DNA-based nanoelectronics in thermal management aspect. Synthesis of crystalline DNA-composited microfiber and microfilm, DNA nanofiber and DNA nanofiber array are developed in sequence to enable the thermal transport study in them. Thermo-physical properties, including thermal conductivity, thermal diffusivity, and volumetric heat capacity, for all of the DNA samples are reported. The thermal conductivity of DNA microfiber is evaluated to be 0.33 W/m·K at room temperature. With the formation of crystalline DNA-NaCl complexes, DNA molecules are speculated to be aligned with the crystal structure of NaCl during crystallization, which results in a significant enhancement of thermal transport. The thermal conduction can also be improved by eliminating structural defects in DNA samples based on the newly-established thermal reffusivity theory. Thermal reffusivity is the inverse of thermal diffusivity and is introduced to quantitatively evaluate phonon scattering induced by structural defects. The structural size for defect-induced phonon scattering is determined to be 0.8 nm for DNA microfiber, in the same order of magnitude as the characteristic size of DNA. As the structural size for defect-induced phonon scattering approaches infinity, the thermal transport potential in defect-free material can be reached. By estimation, the thermal conductivity/diffusivity will be promoted by 36~61% without structural defects in DNA microfiber. Compared to microfiber, DNA nanofiber possesses a higher thermal conductivity due to more condensed and oriented structures, as well as less structural defects. The structural size for defect-induced phonon scattering is 1.6 nm in DNA nanofiber, twice of that in DNA microfiber. The thermal conductivity of DNA nanofiber with perfect structure is predicted to reach 2.3 W/m·K. In addition, nanoscale Ir thin film on DNA microfiber shows a similar intrinsic electrical resistivity as bulk Ir, which is proposed to be preserved by coherent quantum tunneling and diffusive thermal hopping for electron transport in DNA

The Five Ws (and one H) of Super-Hydrophobic Surfaces in Medicine

Super-hydrophobic surfaces (SHSs) are bio-inspired, artificial microfabricated interfaces, in which a pattern of cylindrical micropillars is modified to incorporate details at the nanoscale. For those systems, the integration of different scales translates into superior properties, including the ability of manipulating biological solutions. The five Ws, five Ws and one H or the six Ws (6W), are questions, whose answers are considered basic in information-gathering. They constitute a formula for getting the complete story on a subject. According to the principle of the six Ws, a report can only be considered complete if it answers these questions starting with an interrogative word: who, why, what, where, when, how. Each question should have a factual answer. In what follows, SHSs and some of the most promising applications thereof are reviewed following the scheme of the 6W. We will show how these surfaces can be integrated into bio-photonic devices for the identification and detection of a single molecule. We will describe how SHSs and nanoporous silicon matrices can be combined to yield devices with the capability of harvesting small molecules, where the cut-off size can be adequately controlled. We will describe how this concept is utilized for obtaining a direct TEM image of a DNA molecule

Comprendre et optimiser les anodes microbiennes grâce aux technologies microsystèmes

De multiples micro-organismes ont la capacité de catalyser l’oxydation électrochimique de matières organiques en s’organisant en biofilm à la surface d’anodes. Ce processus est à la base de procédés électro-microbiens très innovants tels que les piles à combustible microbiennes ou les électrolyseurs microbiens. L’interface biofilm/électrode a été l’objet de nombreuses étudesdont les conclusions restent difficiles à démêler en partie du fait de la diversité des paramètres interfaciaux mis en jeu. L’objet de ce travail de thèse est d’exploiter les technologies microsystèmes pour focaliser l’impact de la topographie de surface des électrodes sur le développement du biofilm et sur ses performances électro-catalytiques. La formation de biofilmsélectroactifs de Geobacter sulfurreducens a été étudiée sur des électrodes d’or présentant des topographies bien contrôlées, sous la forme de rugosité, porosité, réseau de piliers, à des échellesallant du nanomètre à quelques centaines de micromètres. La présence de microrugosité a permis d’accroitre les densités de courant d’un facteur 8 par rapport à une surface lisse et son effet a étéquantifié à l’aide du paramètre Sa. Nous avons tenté de distinguer les effets des différentes échelles de rugosité sur le développement du biofilm et la vitesse des transferts électroniques.L’intérêt de la microporosité a été discuté. L’accroissement de surface active par la présence de micro-piliers s’est avéré très efficace et une approche théorique a donné des clés de compréhension et d’optimisation. Les connaissances acquises dans les conditions de culture pure ont finalement été confrontées avec la mise en oeuvre de biofilms multi-espèces issus d’un inoculum complexe provenant de sédiments marins