Electronic properties of single Prussian Blue Analog nanocrystals determined by conductive-AFM.

We report a study of the electron transport (ET) properties at the nanoscale (conductive-AFM denoted as C-AFM hereafter) of individual Prussian Blue Analog (PBA) cubic nanocrystals (NCs) of CsCoFe, with a size between 15 and 50 nm deposited on HOPG. We demonstrate that these PBA NCs feature an almost size-independent electron injection barrier of 0.41 ± 0.

Magnetic Hysteresis in a Monolayer of Oriented 6 nm CsNiCr Prussian Blue Analogue Nanocrystals.

Prussian blue analogue nanocrystals of the CsNi[Cr(CN)] cubic network with 6 nm size were assembled as a single monolayer on highly organized pyrolytic graphite (HOPG). X-ray magnetic circular dichroism (XMCD) studies, at the Ni and Cr L edges, reveal the presence of an easy plane of magnetization evidenced by an opening of the magnetic hysteresis loop (coercive field of ≈200 Oe) when the magnetic field, , is at 60° relative to the normal to the substrate. The angular dependence of the X-ray natural linear dichroism (XNLD) reveals both an orientation of the nanocrystals on the substrate and an anisotropy of the electronic cloud of the Ni and Cr coordination sphere species belonging to the nanocrystals' surface.

Long-range electron transport in Prussian blue analog nanocrystals.

We report electron transport measurements through nano-scale devices consisting of 1 to 3 Prussian blue analog (PBA) nanocrystals connected between two electrodes. We compare two types of cubic nanocrystals, CsCoIIIFeII (15 nm) and CsNiIICrIII (6 nm), deposited on highly oriented pyrolytic graphite and contacted by conducting-AFM. The measured currents show an exponential dependence with the length of the PBA nano-device (up to 45 nm), with low decay factors β, in the range 0.

Photoswitchable 11 nm CsCoFe Prussian Blue Analogue Nanocrystals with High Relaxation Temperature.

Photoswitchable 11 nm nanocrystals with the coordination network Cs{Co[Fe(CN)]} were obtained using a template-free method. The nanocrystals were recovered from the colloidal solutions as solid materials surrounded by cetyltrimethylammonium (CTA) cations or embedded in the organic polymer polyvinylpyrrolidone (PVP). Complementary magnetic, spectroscopic, and structural techniques, including EPR spectroscopy, reveal a majority (∼70%) of the low-spin and photoactive diamagnetic CoFe pairs located in the core of the nanocrystals and a mixture of CoFe and CoFe species present mainly within the shell of the objects.

Rapid and label-free electrochemical DNA biosensor for detecting hepatitis A virus.

Diagnostic systems that can deliver highly specific and sensitive detection of hepatitis A virus (HAV) in food and water are of particular interest in many fields including food safety, biosecurity and control of outbreaks. Our aim was the development of an electrochemical method based on DNA hybridization to detect HAV. A ssDNA probe specific for HAV (capture probe) was designed and tested on DNAs from various viral and bacterial samples using Nested-Reverse Transcription Polymerase Chain Reaction (nRT-PCR).

Surface initiated supplemental activator and reducing agent atom transfer radical polymerization (SI-SARA-ATRP) of 4-vinylpyridine on poly(ethylene terephthalate).

Poly(ethylene terephthalate) (PET) substrates were modified by means of surface-initiated supplemental activator and reducing agent atom transfer radical polymerization (SI-SARA-ATRP) of 4-vinylpyridine (4VP). Substrates were pretreated in order to graft chloromethylbenzene (CMB) units capable of initiating the radical polymerization reaction of 4VP units. Surface characterization techniques, including Water Contact Angle (WCA), Attenuated Total Reflection (ATR), X-ray photoelectron spectroscopy (XPS), Atomic Force Microscopy (AFM) and Time-of-Flight Secondary Ion Mass Spectrometry (ToF-SIMS) showed a successful grafting of a stable, smooth and homogenous layer of p4VP.

Self-assembled monolayer formation of a (N)Fe(ii) complex on gold electrodes: electrochemical properties and coordination chemistry on a surface.

A coordinatively unsaturated Fe complex bearing a pentadentate ligand (N,N',N'-tris(2-pyridyl-methyl)-1,2-diaminoethane) functionalized with a cyclic disulfide group has been prepared in order to graft reactive metal entities as self-assembled monolayers (SAMs) on gold electrodes. Prior to grafting, exogenous ligand exchange has been investigated by cyclic voltammetry (CV) in solution, showing that the nature of the first coordination sphere (N)Fe-X (X = Cl, OTf, MeCN, acetone) can be tuned, thanks to the control of the chemical conditions. The Fe complex has been immobilized on gold electrodes by spontaneous (passive) adsorption as well as by an electro-assisted method.

N-terminal domain of PB1-F2 protein of influenza A virus can fold into amyloid-like oligomers and damage cholesterol and cardiolipid containing membranes.

PB1-F2 protein is a factor of virulence of influenza A viruses which increases the mortality and morbidity associated with infection. Most seasonal H1N1 Influenza A viruses express nowadays a truncated version of PB1-F2. Here we show that truncation of PB1-F2 modified supramolecular organization of the protein in a membrane-mimicking environment.

Amyloid Assemblies of Influenza A Virus PB1-F2 Protein Damage Membrane and Induce Cytotoxicity.

PB1-F2 is a small accessory protein encoded by an alternative open reading frame in PB1 segments of most influenza A virus. PB1-F2 is involved in virulence by inducing mitochondria-mediated immune cells apoptosis, increasing inflammation, and enhancing predisposition to secondary bacterial infections. Using biophysical approaches we characterized membrane disruptive activity of the full-length PB1-F2 (90 amino acids), its N-terminal domain (52 amino acids), expressed by currently circulating H1N1 viruses, and its C-terminal domain (38 amino acids).

Towards bottom-up nanopatterning of Prussian blue analogues.

Ordered nanoperforated TiO2 monolayers fabricated through sol-gel chemistry were used to grow isolated particles of Prussian blue analogues (PBA). The elaboration of the TiO2/CoFe PBA nanocomposites involves five steps. The samples were characterized by scanning electron microscopy (SEM), atomic force microscopy (AFM), infrared spectroscopy and X-ray photoelectron spectroscopy (XPS) all along the synthesis process.

Sequential growth of bistable copper-molybdenum coordination nanolayers on inorganic surfaces.

Sequential growth in solution is a powerful tool to control the growth of coordination networks on surfaces. We used this approach to prepare nanolayers of the bistable copper-molybdenum cyanide-bridged network. The nanolayers were grown on functionalized silicon and on bare platinum surfaces.

Cyanide-bridged NiCr and alternate NiFe-NiCr magnetic ultrathin films on functionalized Si(100) surface.

Sequential growth in solution (SGS) was performed for the magnetic cyanide-bridged network obtained from the reaction of Ni(H(2)O)(2+) and Cr(CN)(6)(3-) (referred to as NiCr) on a Si(100) wafer already functionalized by a Ni(II) complex. The growth process led to isolated dots and a low coverage of the surface. We used the NiFe network as a template to improve the growth of the magnetic network.

Assembly of a magnetic polyoxometalate on SWNTs.

Recently, the organisation of magnetic molecules on carbon nanotubes has raised much interest due to their possible interesting contribution to molecular spintronics. In this paper, we describe the assembly on SWNTs of a magnetic polyoxometalate encompassing a single cobalt ion (CoPOM) and its isostructural diamagnetic zinc analogue (ZnPOM). The simple magnetic behaviour of CoPOM and the availability of its diamagnetic counterpart render these POM@NTs systems interesting model compounds for the study of molecular electronics devices based on carbon nanotubes and magnetic molecules.

Growth and density control of nanometric nickel-iron cyanide-bridged objects on functionalized Si(100) surface.

Isolated nanometric objects of the nickel-iron cyanide-bridged coordination network are obtained by a sequential growth on "molecular seeds" anchored on Si(100) surfaces. Control of the density and the size of the nano-objects is achieved by imposing a growth process without side nucleation.

Magnetic bistability of individual single-molecule magnets grafted on single-wall carbon nanotubes.

A POM to remember: Hexanuclear Fe(III) polyoxometalate (POM) single-molecule magnets (see structure) can be noncovalently assembled on the surface of single-wall carbon nanotubes. Complementary characterization techniques (see TEM image and magnetic hysteresis loops) demonstrate the integrity and bistability of the individual molecules, which could be used to construct single-molecule memory devices.