Horseradish Peroxidase Nanopatterned Electrodes by Click Chemistry: Application to the Electrochemical Detection of Paracetamol

We propose the fabrication of nanostructured glassy carbon (GC) electrodes modified with horseradish peroxidase (HRP) for the detection of paracetamol. This was accomplished by inducing the nanostructuration of GC via the adsorption of polystyrene nanospheres (900 nm diameter) followed by electropolymerization of N‐(10‐azidodecyl)pyrrole. The nanospheres were then removed and nanostructured polypyrrole‐GC was submitted to click reaction in presence of ethynyl‐biotin that was further coupled to HRP‐avidin. The electrode was then used to sense the electrochemical reduction of the enzymatically generated electroactive oxidized species of acetaminophen (NAPQI) in the presence of hydrogen peroxide. The nanostructured electrode with HRP exhibits a fast response towards NAPQI reduction and improved performances in terms of sensitivity and limit of detection compared to non structured electrode.     

Preparation and Characterization of Electrodes Modified with Pyrrole Surfactant,Multiwalled Carbon Nanotubes and Metallophthalocyanines for the Electrochemical Detection of Thiols

Our aim was to prepare hybrid electrodes active towards the electrooxidation of thiols by the co‐immobilization of native carbon nanotubes (CNTs) and cobalt phthalocyanine (CoPc) from aqueous solutions. This strategy was adopted to avoid the oxidation of CNTs that can induce a modification of their exceptional properties. To do so, a hydrosoluble pyrrole surfactant was used to get homogeneous aqueous dispersions of CNTs and CoPc and to trap both materials on the electrode via the electropolymerization of the pyrrole surfactant. The hybrid electrodes exhibit a good electrocatalytic activity towards the oxidation of L ‐cysteine and glutathione. Their performances in terms of limit of detection (0.01 mM) are compatible with the detection of these thiols in biological samples.     

The neuroblast and angioblast chemotaxic factor SDF-1 (CXCL12) expression is briefly up regulated by reactive astrocytes in brain following neonatal hypoxic-ischemic injury

Background  

Stromal cell-derived factor 1 (SDF-1 or CXCL12) is chemotaxic for CXCR4 expressing bone marrow-derived cells. It functions in brain embryonic development and in response to ischemic injury in helping guide neuroblast migration and vasculogenesis. In experimental adult stroke models SDF-1 is expressed perivascularly in the injured region up to 30 days after the injury, suggesting it could be a therapeutic target for tissue repair strategies. We hypothesized that SDF-1 would be expressed in similar temporal and spatial patterns following hypoxic-ischemic (HI) injury in neonatal brain.     

An alternating direction scheme on a nonuniform mesh for reaction-diffusion parabolic problems

In this paper we develop a numerical method for two-dimensionaltime-dependent reaction-diffusion problems. This method, whichcan immediately be generalized to higher dimensions, is shownto be uniformly convergent with respect to the diffusion problems.This method, which can immediately be generalized to higherdimensions, is shown to be uniformly convergent with respectto the diffusion parameter.     

Electrolytic Cell Design to Simulate the Electrochemical Skin Response

Small fiber peripheral neuropathy is an early complication of diabetes. Electric skin response to some stimulus, as electrochemical skin conductance ECS, is a promising route in the early follow‐up of such diseases. It is related to sweat gland innervations and their permeability to chlorides and protons; it is non‐invasive, quantitative and reproducible. In routine clinical use, it could allow to better adapt the treatments and improve the adhesion for preventing pathological progress, thus reducing colossal healthcare costs. To optimize the measurements and understand the electrochemical behavior of electrodes, an original electrolytic cell was designed in lab scale. Thereby, an electrolyte is chosen to mimic sweat composition. For achieving currents range of ESC in vivo measurements, the original idea was to play on electrolyte viscosity by adding sucrose. In this paper, the novel electrolytic lab cell is presented with its limiting kinetics processes. A model of chloride migration to the anode and global electric model dedicated to the cell are proposed. Cell parameters are thoroughly studied, e. g. the resistance, which is equivalent to the inverse of ESC, by exploiting the models and through in vitro experiments, with protocols focusing on reproducibility. This original approach establishes, inter alia, an important result: the resistance is accurately retrieved using linear voltammetry, whereas single voltage measurement fails notably and is, therefore, unsatisfactory.