Karine Gorgy

Single Glucose Biofuel Cells Implanted in Rats Power Electronic Devices

We describe the first implanted glucose biofuel cell (GBFC) that is capable of generating sufficient power from a mammals body fluids to act as the sole power source for electronic devices. This GBFC is based on carbon nanotube/enzyme electrodes, which utilize glucose oxidase for glucose oxidation and laccase for dioxygen reduction. The GBFC, implanted in the abdominal cavity of a rat, produces an average open-circuit voltage of 0.57 V. This implanted GBFC delivered a power output of 38.7 μW, which corresponded to a power density of 193.5 μW cm−2 and a volumetric power of 161 μW mL−1. We demonstrate that one single implanted enzymatic GBFC can power a light-emitting diode (LED), or a digital thermometer. In addition, no signs of rejection or inflammation were observed after 110 days implantation in the rat.

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. The aptamer sensor was applied for the detection and quantification of thrombin via impedimetric detection without a labeling step. A linear quantification of thrombin was obtained in the range 4.7×10(-12)-5.0×10(-10) mol L(-1) with a sensitivity of 2838 Ω/log unit (R(2)=0.9984). The impedance modulus at 0.3 Hz as a function of thrombin concentration was used to elaborate a similar linear relationship from 4.7×10(-12) to 5×10(-10) mol L(-1). In addition, aptamer-poly(pyrrole-NTA) electrodes incubated for 40 min in aqueous solutions of bovine serum albumin (BSA), lysozyme and IgG (5×10(-7) mol L(-1)) did not exhibit non-specific adsorption of proteins. Moreover, it has been demonstrated that the selective sensor can be regenerated several times with a good reproducibility.

Electrochemical nitrate biosensor based on poly(pyrrole–viologen) film–nitrate reductase–clay composite

The immobilization of nitrate reductase (NR) was performed by entrapment in a laponite clay gel and cross-linking by glutaraldehyde. In presence of nitrate and methyl viologen, a catalytic current appeared at -0.60 V illustrating the enzymatic reduction of nitrate into nitrite via the reduced form of the freely diffusing methyl viologen. The electropolymerization of a water-soluble pyrrole viologen derivative within the interlamellar spaces and channels of the host clay matrix successfully carried out the electrical wiring of the entrapped NR. Rotating disk measurements led to the determination of kinetic constants, namely k(2)=10.7 s(-1) and K(M)=7 microM. These parameters reflect the efficiency of the electro-enzymatic reduction of nitrate and the substrate affinity for the immobilized enzyme.

Electrocatalytic oxidation of alcohols using substituted N-hydroxyphthalimides as catalysts

The electrocatalytic oxidation of several alcohols was performed using a new series of substituted N-hydroxyphthalimides as catalysts. The substitution in the N-hydroxyphthalimide structure by electron withdrawing or donor substituents has a beneficial effect on the efficiency of the electrocatalytic oxidation of borneol, used as a model, although the progressive degradation of the catalysts during preparative electrolyses is observed. In the case of lowest activated alcohols such as 2-octanol the use of the regular structure allows the best chemical yield in the corresponding carbonyl compounds to be obtained. Moreover, primary alcohol oxidation under anaerobic conditions leads to the corresponding aldehyde exclusively, whereas in the presence of molecular oxygen a mixture of the corresponding aldehyde and carboxylic acid is obtained.

Electrochemical behaviour of (μ-oxo) di-aqua diiron(III) complexes in organic media. Electrogeneration of mononuclear [FeII(L)2(S)2]2+ complexes (L=2,2′-bipyridine and (−)4,5-pinene-2,2′-bipyridine; S=H2O or CH3CN)

Abstract The electrochemical behaviour of the μ-oxo complexes [Fe 2 III,III O(L) 4 (H 2 O) 2 ] 4+ (L=2,2′-bipyridine (bpy, 1 ) and (−)4,5-pinene-2,2′-bipyridine (pb, 2 )) has been investigated in CH 3 CN. Since some aqua substitution by CH 3 CN can occur (although, it is not demonstrated clearly) [Fe 2 III,III O(L) 4 (S) 2 ] 4+ (S=H 2 O and/or CH 3 CN) is a more accurate notation of complexes 1 and 2 species. Complexes 1 and 2 are reduced irreversibly and on the basis of the electrochemical and spectroscopic data, the reduction process implies an ECC mechanism. The controlled-potential reduction yields an equal amount of the corresponding mononuclear complexes [Fe II (L) 3 ] 2+ and an ill-defined ‘Fe(III) oxide’. It is suggested that the primary one-electron reduced species [Fe 2 II,III O(L) 4 (S) 2 ] 3+ (S=H 2 O or CH 3 CN) decomposes into the mononuclear complex [Fe II (L) 2 (S) 2 ] 2+ by cleavage of the dimeric structure. This mononuclear complex is further transformed into [Fe(L) 3 ] 2+ by the substitution of the S ligands by one L released from the second iron center, remaining at the +III oxidation state. The transformation of [Fe II (L) 2 (S) 2 ] 2+ into [Fe(L) 3 ] 2+ is slower for 2 than for 1 due to larger steric hindrance of the pb ligand versus bpy. Addition of 2 H + to solutions of 1 and 2 in CH 3 CN leads to the formation of new dinuclear [Fe 2 III,III O(L) 2 (S) 6 ] 4+ complexes. Under these conditions the reduction process implies two electrons with quasi-quantitative formation of the mononuclear bis-L complexes [Fe II (L) 2 (S) 2 ] 2+ by a controlled-potential reduction. The implication of the redox behaviour of complexes 1 and 2 reported here with regard to their catalytic activity is discussed. It appears that the better stability and efficiency of 2 versus 1 as a catalyst for cyclohexane oxidation with tert -butyl hydroperoxide (TBHP) can be related to the slower rate of conversion of [Fe II (L) 2 (S) 2 ] 2+ into the inactive species [Fe(L) 3 ] 2+ for 2 .

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. This original method to graft biomolecules combines electrochemical and photochemical techniques. The simplicity of this new method allows it to be extended easily to other biological systems.

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) .

Electrogeneration and characterization of a poly(pyrrole–nickel (II) chlorin) electrode

We describe herein, the electrochemical properties of an hydroporphyrin of Ni(II) substituted by two pyrrole groups in organic media (THF and CH2Cl2). In the anodic region it has been shown that the electrochemical behaviour of this complex investigated by cyclic voltammetry and coulometry coupled with UV–visible spectroscopy is strongly dependent on the nature of the solvent. Furthermore, the electrochemical oxidation of the pyrrrole groups has led to the first example of an electrogenerated polypyrrole–metallochlorin film. The resulting modified electrodes exhibit the same electrochemical properties as the monomer free in solution. Preliminary experiments have also demonstrated the possibility to study electrochemically this polymeric film in CH3CN contrary to the Ni(II) chlorin, which is insoluble in this medium.

An easy electrochemical procedure for tailoring thin films containing the [Fe(bpy)2(CH3CN)2]2+ and/or [Fe(bpy)3]2+-like cores (bpy=2,2′-bipyridine). Application to the design of a modified electrode with a supramolecular structure

Abstract A simple electrochemical procedure to tailor thin polymeric films containing the [Fe II (bpy) 2 (CH 3 CN) 2 ] 2+ and/or [Fe II (bpy) 3 ] 2+ -like cores have been described (bpy=2,2 ′ -bipyridine). The procedure is based on the electroreductive precipitation of soluble polymers prepared in situ in CH 3 CN by mixing Fe 3+ ions and a bis bipyridyl ligand, (chiragen: chir). In the resulting [Fe II (chir)(CH 3 CN) 2 ] n 2+ films, the two labile S ligands can be easily replaced by a bidentate ligand. This method has been applied with success to design a modified electrode with a supramolecular structure.