WITHDRAWN: Static High-Gradient Magnetic Fields Activate Transient Receptor Potential Vanilloid 4 (TRPV4) Ion Channels Enabling Remote Control of Cell Function.

This manuscript has been withdrawn by the Author's request.

Holographic photopolymerization combined to microfluidics for the fabrication of lab-in-lab microdevices and complex 3D micro-objects.

We show here brand-new possibilities of lab-in-lab fabrication while combining holographic photopolymerization and microfluidics. One shot real-time 3D-printing can produce 3D architectured microchannels, or free-standing complex micro-objects eventually in flow. The methodology is very versatile and can be applied to e.g., acrylate resins or hydrogels.

Electrical and Optical Properties of CaTi1-yFeyO3-δ Perovskite Films as Interlayers for Optoelectronic Applications.

CaTi1-yFey O3-δ perovskite oxide films are promising candidate materials for p-type interlayers of third generation solar cells or light-emitting devices. The impact of atomic Ti substitutions by Fe on electrical and optical properties of CaTi0.5Fe0.5O3-δ perovskite films have been studied. The best compromise between a high transmission coefficient and the suitable electrical conductivity is obtained for a specific atomic composition of Ca (1) Ti (0.5) Fe (0.5) O (3-δ) perovskite films. This paper shows that CaTi1-yFeyO3-δ perovskite oxides can be integrated as p-type interfacial layers of optoelectronic devices through their work functions, electrical, and optical properties.

Thermophysical characterisation of VO2 thin films hysteresis and its application in thermal rectification.

Hysteresis loops exhibited by the thermophysical properties of VO2 thin films deposited on either a sapphire or silicon substrate have been experimentally measured using a high frequency photothermal radiometry technique. This is achieved by directly measuring the thermal diffusivity and thermal effusivity of the VO2 films during their heating and cooling across their phase transitions, along with the film-substrate interface thermal boundary resistance. These thermal properties are then used to determine the thermal conductivity and volumetric heat capacity of the VO2 films. A 2.5 enhancement of the VO2 thermal conductivity is observed during the heating process, while its volumetric heat capacity does not show major changes. This sizeable thermal conductivity variation is used to model the operation of a conductive thermal diode, which exhibits a rectification factor about 30% for small temperature differences (≈70 °C) on its terminals. The obtained results grasp thus new insights on the control of heat currents.

Mechanotransductive cascade of Myo-II-dependent mesoderm and endoderm invaginations in embryo gastrulation.

Animal development consists of a cascade of tissue differentiation and shape change. Associated mechanical signals regulate tissue differentiation. Here we demonstrate that endogenous mechanical cues also trigger biochemical pathways, generating the active morphogenetic movements shaping animal development through a mechanotransductive cascade of Myo-II medio-apical stabilization. To mimic physiological tissue deformation with a cell scale resolution, liposomes containing magnetic nanoparticles are injected into embryonic epithelia and submitted to time-variable forces generated by a linear array of micrometric soft magnets. Periodic magnetically induced deformations quantitatively phenocopy the soft mechanical endogenous snail-dependent apex pulsations, rescue the medio-apical accumulation of Rok, Myo-II and subsequent mesoderm invagination lacking in sna mutants, in a Fog-dependent mechanotransductive process. Mesoderm invagination then activates Myo-II apical accumulation, in a similar Fog-dependent mechanotransductive process, which in turn initiates endoderm invagination. This reveals the existence of a highly dynamic self-inductive cascade of mesoderm and endoderm invaginations, regulated by mechano-induced medio-apical stabilization of Myo-II.

Magnetic nanoparticle DNA labeling for individual bacterial cell detection and recovery.

A culture independent approach was developed for recovering individual bacterial cells out of communities from complex environments including soils and sediments where autofluorescent contaminants hinder the use of fluorescence based techniques. For that purpose fifty nanometer sized streptavidin-coated superparamagnetic nanoparticles were used to chemically bond biotin-functionalized plasmid DNA molecules. We show that micromagnets can efficiently trap magnetically labeled transformed Escherichia coli cells after these bacteria were subjected to electro-transformation by these nanoparticle-labeled plasmids. Among other applications, this method could extend the range of approaches developed to study DNA dissemination among environmental bacteria without requiring cultivability of recombinant strains or expression of heterologous genes in the new hosts.

Life on magnets: stem cell networking on micro-magnet arrays.

Interactions between a micro-magnet array and living cells may guide the establishment of cell networks due to the cellular response to a magnetic field. To manipulate mesenchymal stem cells free of magnetic nanoparticles by a high magnetic field gradient, we used high quality micro-patterned NdFeB films around which the stray field's value and direction drastically change across the cell body. Such micro-magnet arrays coated with parylene produce high magnetic field gradients that affect the cells in two main ways: i) causing cell migration and adherence to a covered magnetic surface and ii) elongating the cells in the directions parallel to the edges of the micro-magnet. To explain these effects, three putative mechanisms that incorporate both physical and biological factors influencing the cells are suggested. It is shown that the static high magnetic field gradient generated by the micro-magnet arrays are capable of assisting cell migration to those areas with the strongest magnetic field gradient, thereby allowing the build up of tunable interconnected stem cell networks, which is an elegant route for tissue engineering and regenerative medicine.

Evolutionary conservation of early mesoderm specification by mechanotransduction in Bilateria.

The modulation of developmental biochemical pathways by mechanical cues is an emerging feature of animal development, but its evolutionary origins have not been explored. Here we show that a common mechanosensitive pathway involving ß-catenin specifies early mesodermal identity at gastrulation in zebrafish and Drosophila. Mechanical strains developed by zebrafish epiboly and Drosophila mesoderm invagination trigger the phosphorylation of ß-catenin-tyrosine-667. This leads to the release of ß-catenin into the cytoplasm and nucleus, where it triggers and maintains, respectively, the expression of zebrafish brachyury orthologue notail and of Drosophila Twist, both crucial transcription factors for early mesoderm identity. The role of the ß-catenin mechanosensitive pathway in mesoderm identity has been conserved over the large evolutionary distance separating zebrafish and Drosophila. This suggests mesoderm mechanical induction dating back to at least the last bilaterian common ancestor more than 570 million years ago, the period during which mesoderm is thought to have emerged.