The Impact of the Functional Layer Composition of Glucose Test-Strips on the Stability of Electrochemical Response

Herein, the impact of the chemical stability of RedOx mediator ferricyanide, K3 [Fe(CN)6 ] (FC), a type of buffer solution used for bioreceptor preparation, gel composition (carboxymethylcellulose, CMC, Aerosile, AS, and alginate, ALG) on the long term stability of glucose test-strips and their analytical performance was examined. By simple addition of ALG to the functional gel aiming to improve its viscosity, we managed to enhance the sensitivity of conventional CMC-containing amperometric glucose test-strips from 3.3 µA/mM to 3.9 µA/mM and extend their shelf life from 8 months to 1.7 years. Moreover, during the course of investigations, it was revealed that the activity of enzyme in dependence with the used buffer did not linearly correlate with its activity in a dried functional layer, and the entire long-term electrochemical signal of glucose test-strips was determined by RedOx mediator FC chemical stability. The most stable and sensitive test-strips were obtained by the screen-printing approach from a gel containing 24 mg/mL GOx prepared in citrate buffer with pH 6, 200 mg/mL of FC and 10 mg/mL of CMC supplemented with 25 mg/mL of ALG

One-Pot Synthesis of Copper Iodide-Polypyrrole Nanocomposites

A novel one-pot chemical synthesis of functional copper iodide-polypyrrole composites, CuI-PPy, has been proposed. The fabrication process allows the formation of nanodimensional metal salt/polymer hybrid structures in a fully controlled time- and concentration-dependent manner. The impact of certain experimental conditions, viz., duration of synthesis, sequence of component addition and concentrations of the intact reagents on the structure, dimensionality and yield of the end-product was evaluated in detail. More specifically, the amount of marshite CuI within the hybrid composite can be ranged from 60 to 90 wt.%, depending on synthetic conditions (type and concentration of components, process duration). In addition, the conditions allowing the synthesis of nano-sized CuI distributed inside the polypyrrole matrix were found. A high morphological stability and reproducibility of the synthesized nanodimensional metal-polymer hybrid materials were approved. Finally, the electrochemical activity of the formed composites was verified by cyclic voltammetry studies. The stability of CuI-PPy composite deposited on the electrodes was strongly affected by the applied anodic limit. The proposed one-pot synthesis of the hybrid nanodimensional copper iodide-polypyrrole composites is highly innovative, meets the requirements of Green Chemistry and is potentially useful for future biosensor development. In addition, this study is expected to generally contribute to the knowledge on the hybrid nano-based composites with tailored properties

Electrochromic properties of Prussian blue–polypyrrole composite films in dependence on parameters of synthetic procedure

International audienceComposite materials of Prussian blue-polypyrrole (PB/PPy) on the surface of indium tin oxide (ITO)-coated glasses were obtained via one-step chemical (redox) and one-stage electrochemical procedures in mixed solution of iron (III), hexacyanoferrate (III), and pyrrole with various concentration ratios of components in nitrate supporting electrolyte. Electrochemical stability of composite films depends on the amount of Py in synthetic solution, whereas color contrast coefficient values depend on the type of synthetic procedure. PB/PPy film electrochromic response (tested by spectroelectrochemical potentiodynamic measurements) was compared with response of both pure PB and pure PPy films. It was shown that degradation of composite films occurs due to PB component instability in Prussian white form. The highest value of color contrast coefficient and great electrochemical stability were revealed for composite films obtained via redox-synthesis procedure from solution with 0.1 mM [Fe3+ + Fe(CN)(6) (3-)] and 1.0 mM D N integral (PB/PPy-Ch-1:1:10 system)

Nanostructured Prussian Blue–polypyrrole composite coatings with electrochromic properties

International audienceThe Prussian Blue-polypyrrole (PB/PPy) composite materials were obtained by a chemical redox process in a mixed solution of iron(III), hexacyanoferrate(III) and pyrrole with a nitrate supporting electrolyte. The morphology of the composites (as a sedimented powder or a film on the ITO-glass electrode surface) varied depending on the composition of synthetic solution

Pd–PPy nanocomposite on the surface of carbon nanotubes: synthesis and catalytic activity

International audienceIn the presence of carbon nanotubes (CNTs), palladium (Pd)-polypyrrole (PPy)@CNT nanocomposites have been synthesized by way of one-pot and one-step colloidal synthesis from a solution of a palladium inorganic salt and organic pyrrole as monomeric precursor to PPy. This efficient method leads to the growth of nanoparticles of the palladium inorganic component distributed inside a polymer matrix supported on CNTs. After characterization, palladium-PPy@CNT nanocomposites have been employed as efficient heterogeneous catalysts for direct C-H bond functionalization toward C-C bond coupling formation. The notable catalytic activity of the palladium-PPy@CNT nanocomposite decreased with successive catalytic cycles when using the same portion of the composite. This was attributed to palladium redistribution inside the PPy matrix, which occurs by way of a specific mechanism involving the reaction solvent and the composite during C-C coupling reaction. This mechanism is recrystallization of palladium nanoparticles in conductive PPy matrix. Nevertheless, the use of palladium-PPy@CNT nanocomposite in first cycle of investigated catalytic reaction facilitates C-C bond coupling formation: reaction occurs at lower temperature in comparison with homogeneous catalysts

Neuropsychological diagnostics of neurosarcoidosis

This article presents the results of neuropsychological studies of the patients with neurosarcoidosis. The obtained results show that typical manifestations of neurosarcoidosis are disorders of motor functions. They appear in the speed reduction of actions and their accuracy, which prove peripheral neuropathy and myopathy at the functional level as clinical signs of neurosarcoidosis. Specific manifestations of neurosarcoidosisare determinedby topographical localization of granulomatoma

Polypyrrole-palladium nanoparticles composite as efficient catalyst for Suzuki-Miyaura coupling

International audienceSynthesis of a new hybrid material (Pd/PPy) composed of polypyrrole globules with uniformly incorporated Pd nanoparticles via direct redox reaction between pyrrole and Pd(NH3)(4)Cl-2 in water has been recently reported (V.A. Zinovyeva, M.A.Vorotyntsev, I. Bezverkhyy, D. Chaumont, J.-C. Hierso, Adv. Funct. Mater. 21 (2011) 1064-1075). In the actual study, this procedure has been extended to synthesize a series of Pd/PPy powders with variable palladium content and morphological parameters. Depending on the monomer-to-oxidant ratio in reaction mixture, average diameters of Pd and PPy particles may change in the ranges of 1.25-1.45 and 27-62 nm, respectively, the Pd concentration being within 33.5-42.0 wt.%. In general terms, decrease of the monomer-to-oxidant ratio led to formation of the Pd/PPy hybrid material with smaller diameters of both components and a higher Pd loading. The Pd/PPy composites have been studied in Suzuki-Miyaura coupling and showed high catalytic efficiency. Aryl iodides, bromides and chlorides are active. The reaction can be performed using arylboronic acids or tetraarylborates, both in organic solvents and in water, thus making the process ecologically friendly. The recycling of the catalyst is possible if its particles are immobilized on the graphite support. The comparison of two samples revealed that Pd/PPy nanocomposite with the diameter of PPy spheres of about 30 nm is more efficient in catalysis, as compared to the sample with bigger PPy spheres (about 60 nm), due to transport limitations for reagents inside the polypyrrole sphere in the latter case. For palladium/polypyrrole nanocomposites with the small diameter of PPy sphere, which are easily penetrable for the reagents and in which all Pd nanoparticles are active. Pd content in polypyrrole spheres does not influence the yield of biaryls: the more is the Pd content in polypyrrole spheres, the less amount of catalyst is necessary to obtain the same yield of biaryl

Genome instability in MCF-7 cells exposed to gDNA^OX at final concentration 50 ng/mL for 24 hours.

<div><p>A – multiple micronuclei [<a href="http://www.plosone.org/article/info:doi/10.1371/journal.pone.0077469#B1" target="_blank">1</a>], chromatin bridges [<a href="http://www.plosone.org/article/info:doi/10.1371/journal.pone.0077469#B2" target="_blank">2</a>], M-phase chromatin decondensation [<a href="http://www.plosone.org/article/info:doi/10.1371/journal.pone.0077469#B3" target="_blank">3</a>], non-treated control cells [<a href="http://www.plosone.org/article/info:doi/10.1371/journal.pone.0077469#B4" target="_blank">4</a>] (x100). </p> <p>B – proportions of cells with micronuclei in non-treated control cells, cells exposed to gDNA, cells exposed to gDNA<b>^OX</b>. Grey columns: non-confluent, actively proliferating MCF-7 culture. Black columns: MCF-7 cells at high confluency. *p < 0.05 against control group of cells, non-parametric U-test.</p> <p>С - Exposure to gDNA<b>^OX</b> (50 ng/mL, 2 hours) induces formation of 8-oxodG-containing micronuclei (x100). </p></div

The analysis of 8-oxodG content in cells exposed to either gDNA or gDNA^OX (50 ng/mL).

<p>A - Cells stained with PE-labeled anti-8-oxodG antibodies and DAPI (x20). B - Three types of anti-8-oxodG stain distribution observed in cells treated with gDNA<b>^OX</b> (x100). Cell were incubated with DNA samples for 1 hour, fixed with 3% formaldehyde, permeated with 0,1 % triton X100 and stained with anti-8-oxodG (PE-conjugated secondary antibodies). C – colocalization of 8-oxodG with mitochondria. Cells were incubated with <b>gDNA^OX</b> for 0.5 hour, обработаны Mito-tracker (30 nM, 15 min), photographed, then fixed with 3% formaldehyde, permeated with 0,1 % triton X100, stained with anti-8-oxodG antibodies (FITC-conjugated secondary antibodies) and photographed again. D - 8-oxodG content in DNA exposed cells pre-treated with NAC (FACS analysis). Cells were incubated with NAC (0.15 mM) for 30 min, then exposed to gDNA^OX for 1 hour and analyzed using anti-8-oxodG antibodies (PE-conjugated secondary antibodies). Background fluorescence was quantified using PE-conjugated secondary antibodies. E - Relative proportions of nuclei stained for 8-oxodG in non-treated control cells, cells exposed to gDNA, cells exposed to gDNA^OX (grey columns). Light grey column reflects cells pre-treated with NAC and exposed to gDNA^OX. *p < 0.05 against control group of cells, non-parametric U-test.</p