Electrochemistry of ferrocenylphosphines FcCH₂PR₂ (Fc=(η⁵-C₅H₅)Fe(η⁵-C₅H₄); R=Ph, CH₂OH and CH₂CH₂CN), and some phosphine oxide, phosphine sulfide, phosphonium and metal complex derivatives

Electrochemical studies of the free ferrocenylphosphine ligands FcCH₂PR₂ (Fc=(η⁵-C₅H₅)Fe(η⁵-C₅H₄); R=Ph, CH₂OH and CH₂CH₂CN) and some phosphine oxide, phosphine sulfide, phosphonium and metal derivatives are described. The free ligands exhibit complex voltammetric responses due to participation of the phosphorus lone pair in the redox reactions. Uncomplicated ferrocene-based redox chemistry is observed for PV derivatives and when the ligands are coordinated in complexes cis-PtCl₂[FcCH₂P(CH₂OH)₂], PdCl₂[FcCH₂P(CH₂OH)₂], [Au{FcCH₂P(CH₂OH)₂}₂]Cl, RuCl₂(η⁶-C₁₀H₁₄)[FcCH₂P(CH₂OH)₂] and RuCl₂(η⁶-C₁₀H₁₄)(FcCH₂PPh₂). The reaction pathways of the free ligands after one-electron oxidation have been examined in detail using voltammetry, NMR spectroscopy and electrospray mass spectrometry. Direct evidence for formation of a P---P bonded product is presented

Electrowetting on conductors: Anatomy of the phenomenon

We have recently reported that reversible electrowetting can be observed on the basal plane of graphite, without the presence of a dielectric layer, in both liquid/air and liquid/liquid configurations. The influence of carbon structure on the wetting phenomenon is investigated in more detail here. Specifically, it is shown that the adsorption of adventitious impurities on the graphite surface markedly suppresses the electrowetting response. Similarly, the use of pyrolysed carbon films, although exhibiting a roughness below the threshold previously identified as the barrier to wetting on basal plane graphite, does not give a noticeable electrowetting response, which leads us to conclude that specific interactions at the water–graphite interface as well as graphite crystallinity are responsible for the reversible response seen in the latter case. Preliminary experiments on mechanically exfoliated and chemical vapour deposition grown graphene are also reported.</p

New Perspectives on Iron Uptake in Eukaryotes

All eukaryotic organisms require iron to function. Malfunctions within iron homeostasis have a range of physiological consequences, and can lead to the development of pathological conditions that can result in an excess of non-transferrin bound iron (NTBI). Despite extensive understanding of iron homeostasis, the links between the “macroscopic” transport of iron across biological barriers (cellular membranes) and the chemistry of redox changes that drive these processes still needs elucidating. This review draws conclusions from the current literature, and describes some of the underlying biophysical and biochemical processes that occur in iron homeostasis. By first taking a broad view of iron uptake within the gut and subsequent delivery to tissues, in addition to describing the transferrin and non-transferrin mediated components of these processes, we provide a base of knowledge from which we further explore NTBI uptake. We provide concise up-to-date information of the transplasma electron transport systems (tPMETSs) involved within NTBI uptake, and highlight how these systems are not only involved within NTBI uptake for detoxification but also may play a role within the reduction of metabolic stress through regeneration of intracellular NAD(P)H/NAD(P)+ levels. Furthermore, we illuminate the thermodynamics that governs iron transport, namely the redox potential cascade and electrochemical behavior of key components of the electron transport systems that facilitate the movement of electrons across the plasma membrane to the extracellular compartment. We also take account of kinetic changes that occur to transport iron into the cell, namely membrane dipole change and their consequent effects within membrane structure that act to facilitate transport of ions

Fast, ultrasensitive detection of reactive oxygen species using a carbon nanotube based-electrocatalytic intracellular sensor

Herein, we report a highly sensitive electrocatalytic sensor-cell construct that can electrochemically communicate with the internal environment of immune cells (e.g., macrophages) via the selective monitoring of a particular reactive oxygen species (ROS), hydrogen peroxide. The sensor, which is based on vertically aligned single-walled carbon nanotubes functionalized with an osmium electrocatalyst, enabled the unprecedented detection of a local intracellular “pulse” of ROS on a short second time scale in response to bacterial endotoxin (lipopolysaccharide-LPS) stimulation. Our studies have shown that this initial pulse of ROS is dependent on NADPH oxidase (NOX) and toll like receptor 4 (TLR4). The results suggest that bacteria can induce a rapid intracellular pulse of ROS in macrophages that initiates the classical innate immune response of these cells to infection

Boron-doped diamond dual-plate deep-microtrench device for generator-collector sulfide sensing

International audienceA BDD-BDD dual-plate microtrench electrode with 6 μm inter-electrode spacing is investigated using generator-collector electrochemistry and shown to give microtrench depth-dependent sulfide detection down to the μM levels. The effect of the microtrench depth is compared for a “shallow” 44 μm and a “deep” 180 μm microtrench and linked to the reduction of oxygen to hydrogen peroxide which interferes with sulfide redox cycling. With a deeper microtrench and a fixed collector potential at −1.4 V vs. SCE, two distinct redox cycling potential domains are observed at 0.0 V vs. SCE (2-electron) and at 1.1 V vs. SCE (6-electron)