Nanostructured electrodes based on multiwalled carbon nanotube/glyconanoparticles for the specific immobilization of bilirubin oxidase: Application to the electrocatalytic O reduction.

Here we describe the design and the characterization of novel electrode materials consisting of multi-walled carbon nanotubes coated with glyconanoparticles (GNPs) functionalized with anthraquinone sulfonate. The resulting modified electrodes were characterized by scanning electron microscopy and cyclic voltammetry. Their electrochemical behavior reveals a stable pH-dependent redox signal characteristic of anthraquinone sulfonate.

Trialkoxyheptazine-Based Glyconanoparticles for Fluorescence in Aqueous Solutions and on Surfaces via Controlled Binding in Space.

The fluorescent organic 2,5,8-tris((adamantan-1-yl)-methoxy)-heptazine (HTZ-Ad) was solubilized in water by inclusion of adamantane groups into free β-cyclodextrins or a cyclodextrin shell of glyconanoparticles. These glyconanoparticles with average diameters between 40 and 60 nm result from the self-assembly of polystyrene--β-cyclodextrin copolymers. Under UV irradiation at 365 nm, the modified nanoparticles exhibit fluorescence emission in aqueous media as well as in their adsorbed state.

Organic β-cyclodextrin Nanoparticle: An Efficient Building Block Between Functionalized Poly(pyrrole) Electrodes and Enzymes.

Glyconanoparticles (GNPs) made by self-assembly of carbohydrate-based polystyrene-block-β-cyclodextrin copolymer are used as a building block for the design of nanostructured biomaterials of electrode. The firm immobilization of GNPs is carried out on electrochemically generated polymer, poly(pyrrole-adamantane), and copolymer, poly(pyrrole-adamantane)/poly(pyrrole-lactobionamide) via host-guest interactions between adamantane and β-cyclodextrin. The ability of GNPs for the specific anchoring of biological macromolecules is investigated using glucose oxidase enzyme modified by adamantane groups as a protein model (GOx-Ad).

Functionalizable Glyconanoparticles for a Versatile Redox Platform.

A series of new glyconanoparticles (GNPs) was obtained by self-assembly by direct nanoprecipitation of a mixture of two carbohydrate amphiphilic copolymers consisting of polystyrene-block-β-cyclodextrin and polystyrene-block-maltoheptaose with different mass ratios, respectively 0-100, 10-90, 50-50 and 0-100%. Characterizations for all these GNPs were achieved using dynamic light scattering, scanning and transmission electron microscopy techniques, highlighting their spherical morphology and their nanometric size (diameter range 20-40 nm). In addition, by using the inclusion properties of cyclodextrin, these glyconanoparticles were successfully post-functionalized using a water-soluble redox compound, such as anthraquinone sulfonate (AQS) and characterized by cyclic voltammetry.

Microcapsule-based biosensor containing catechol for the reagent-free inhibitive detection of benzoic acid by tyrosinase.

A biosensor based on the release of the enzyme substrate from its structure was developed for the inhibitive detection of benzoic acid. A polyurethane support comprising two perforated microcapsules (800 μm in diameter) filled with methylene blue as a model compound and covered with a conductive deposit of multiwalled carbon nanotubes, continuously released this stored dye for 24 h. An increase in methylene blue concentration of 0.

Photoelectrochemically-assisted biofuel cell constructed by redox complex and g-CN coated MWCNT bioanode.

Herein, we report a membraneless glucose and air photoelectrochemical biofuel cell (PBFC) with a visible light assisted photobioanode. Flavin adenine dinucleotide dependent glucose dehydrogenase (FADGDH) was immobilized on the combined photobioanode for the visible light assisted glucose oxidation (GCE|MWCNT|g-CN|Ru-complex|FADGDH) with a quinone mediated electron transfer. Bilirubine oxidase (BOx) immobilized on MWCNT coated GCE (GCE|BOx) was used as the cathode with direct electron transfer (DET).

Highly Sensitive Bisphenol-A Electrochemical Aptasensor Based on Poly(Pyrrole-Nitrilotriacetic Acid)-Aptamer Film.

An electrochemical highly sensitive aptasensor was developed based on electropolymerized poly(pyrrole-nitrilotriacetic) acid film and a new aptamer functionalized by a pentahistidine peptide for the quantification of bisphenol A. A surface coverage of antibisphenol A aptamer of 1.84 × 10(-10) mol cm(-2) was estimated from the electrochemical signal of the [Ru(III)(NH3)6](3+) complex bound by electrostatic interactions onto the aptamer-modified electrode.

First Occurrence of Tetrazines in Aqueous Solution: Electrochemistry and Fluorescence.

The photophysical and electrochemical properties of tetrazines substituted by linear 2,3-naphtalimide antennas and/or adamantane groups specifically dedicated to host-guest interactions with cyclodextrins are studied both in organic and aqueous media. In acetonitrile solvent, the reduction potential of tetrazine leading to the anion radical is shifted, depending on the electron-withdrawing power of the substituent of the tetrazines. Due to the hydrophobic character of these compounds, their solubilization in aqueous solution is achieved successively in presence of either β-cyclodextrins or gold nanoparticules modified by β-cyclodextrins.

Label-free photoelectrochemical detection of double-stranded HIV DNA by means of a metallointercalator-functionalized electrogenerated polymer.

The design of photoactive functionalized electrodes for the sensitive transduction of double-stranded DNA hybridization is reported. Multifunctional complex [Ru(bpy-pyrrole)2 (dppn)](2+) (bpy-pyrrole=4-methyl-4'-butylpyrrole-2,2'-bipyridine, dppn=benzo[i]dipyrido[3,2-a:2',3'-c]phenazine) exhibiting photosensitive, DNA-intercalating, and electropolymerizable properties was synthesized and characterized. The pyrrole groups undergo oxidative electropolymerization on planar electrodes forming a metallopolymer layer on the electrode.

Biofunctionalization of multiwalled carbon nanotubes by electropolymerized poly(pyrrole-concanavalin A) films.

The synthesis and electropolymerization of a pyrrolic concanavalin A derivative (pyrrole-Con A) onto a multiwalled carbon nanotube (MWCNT) deposit is reported. Glucose oxidase was then immobilized onto the MWCNT-poly(pyrrole-Con A) coating by affinity carbohydrate interactions with the polymerized Con A protein. The resulting enzyme electrode was applied to the amperometric detection of glucose exhibiting a high sensitivity of 36 mA cm(-2) mol(-1) L and a maximum current density of 350 μA cm(-2) .

Permeability improvements of electropolymerized polypyrrole films using dissolvable nano-CaCO3 particle templates.

The electropolymerisation of N-substituted pyrroles on a dissolvable calcium carbonate nanoparticle template was investigated in order to improve the film permeabilities in aqueous solution. After deposition of CaCO3 nanoparticles on the electrode surface, poly(pyrrole-ammonium) or poly(pyrrole-NTA) (NTA: nitrilotriacetic acid) were electrogenerated around the template structures of the electrodes using potentiostatic methods. The dissolution of nanoparticles in acidic medium leads to the formation of nano-porous structures increasing, therefore, the polypyrrole permeability in aqueous solutions.

Biofunctionalization of multiwalled carbon nanotubes by irradiation of electropolymerized poly(pyrrole-diazirine) films.

A photoactivatable poly(pyrrole-diazirine) film was synthesized and electropolymerized as a versatile tool for covalent binding of laccase and glucose oxidase on multiwalled carbon nanotube coatings and Pt, respectively. Irradiation of the functionalized nanotubes allowed photochemical grafting of laccase and its subsequent direct electrical wiring, as illustrated by the electrocatalytic reduction of oxygen. Moreover, covalent binding of glucose oxidase as model enzyme, achieved by UV activation of electropolymerized pyrrole-diazirine, allowed a glucose biosensor to be realized.

Label-free impedimetric thrombin sensor based on poly(pyrrole-nitrilotriacetic acid)-aptamer film.

A label-free and highly sensitive impedimetric aptasensor was developed based on electropolymerized film for the determination of thrombin. The first step is the electrogeneration of a poly(pyrrole-nitrilotriacetic acid) (poly(pyrrole-NTA)) film onto the surface of electrodes followed by complexation of Cu(2+) ions. Then, the histidine labeled thrombin aptamer was immobilized onto the electrode through coordination of the histidine groups on the NTA-Cu(2+) complex.

In situ synthesis of stable mixed ligand Fe2+ complexes on bipyridinyl functionalized electrodes and nanotube supports.

A simple method is presented to synthesize asymmetric mixed ligand iron(II) diimine complexes using bipyridinyl functionalized carbon nanotubes. The synthesis of these complexes was realized using subsequent dip coating processes. The in situ formed mixed ligand complexes were used in aqueous media to act as building blocks in biosensor devices.

A glucose biofuel cell implanted in rats.

Powering future generations of implanted medical devices will require cumbersome transcutaneous energy transfer or harvesting energy from the human body. No functional solution that harvests power from the body is currently available, despite attempts to use the Seebeck thermoelectric effect, vibrations or body movements. Glucose fuel cells appear more promising, since they produce electrical energy from glucose and dioxygen, two substrates present in physiological fluids.

Impedimetric immunosensor based on a polypyrrole-antibiotic model film for the label-free picomolar detection of ciprofloxacin.

This paper describes the construction of an impedimetric immunosensor for the label-free detection of ciprofloxacin, an antibiotic belonging to synthetic fluoroquinolones. A poly(pyrrole-N-hydroxysuccinimide) film was electrogenerated onto electrodes and then used for the reagentless covalent binding of a fluoroquinolone model bearing an amino group. The resulting electrodes were utilized to immobilize a layer of anticiprofloxacin antibody onto the polymer surface by immunoreaction.

Influence of the presence of a gel in the water phase on the electrochemical transfer of ionic forms of beta-blockers across a large water 1,2-dichloroethane interface.

The transfer of ionic species of three beta-blockers (propranolol, sotalol and timolol) has been studied by cyclic voltammetry at a macroscopic water 1,2-dichloroethane (1,2-DCE) interface. The aqueous solution has been gellified in order to study the effect of the gel on the transport properties of the drugs. The gelling agent also stabilizes the interface overcoming mechanical instability.

Sulfide oxidation by hydrogen peroxide catalyzed by iron complexes: two metal centers are better than one.

Peroxoiron species have been proposed to be involved in catalytic cycles of iron-dependent oxygenases and in some cases as the active intermediates during oxygen-transfer reactions. The catalytic properties of a mononuclear iron complex, [Fe(II)(pb)(2)(CH(3)CN)(2)] (pb=(-)4,5-pinene-2,2'-bipyridine), have been compared to those of its related dinuclear analogue. Each system generates specific peroxo adducts, which are responsible for the oxidation of sulfides to sulfoxides.