Gilbert Reverdy

A biosensor as warning device for the detection of cyanide, chlorophenols, atrazine and carbamate pesticides

Abstract The determination of cyanide, chlorophenols, atrazine, dithiocarbamate and carbamate pesticides is described, utilizing an amperometric biosensor constructed by the electropolymerization of a pyrrole amphiphilic monomer-tyrosinase coating. Measurements were carried out with catechol, dopamine, l -DOPA or epinephrine as an enzyme substrate; the enzymatically generated quinoid products being electroreduced at -200 mV vs. SCE. The detection of these water pollutants was performed via their inhibiting action on the tyrosinase electrode. The characterization of the inhibition processes (competitive /non-competitive) and their reversibility were examined. The detection limits are 0.4, 2, 2, 4 and 0.02 μM for 3,4-dichlorophenol, chloroisopropylphenylcarbamate, 3-chloroaniline, atrazine and cyanide, respectively.

Improvement of the analytical characteristics of an enzyme electrode for free and total cholesterol via laponite clay additives

Abstract The electropolymerization of a laponite nanoparticle-amphiphilic pyrrole derivative-enzyme mixture preadsorbed on the electrode surface provides simultaneously the immobilization of the enzyme and the laponite particles in the polypyrrolic matrix. These incorporated laponite nanoparticles greatly enhance the sensitivity and stability of a cholesterol oxidase-based biosensor. Compared to a similar biosensor without laponite, the biosensor sensitivity increased from 5.1 to 13.2 mA M −1 cm −2 . Furthermore, the presence of hydrophilic laponite additive in the polymeric matrix containing cholesterol oxidase and cholesterol esterase is essential for the successful determination of total cholesterol.

Determination of phenol and chlorinated phenolic compounds based on a PPO-bioelectrode and its inhibition

Abstract A polyphenol oxidase (PPO) enzyme electrode constructed by the electropolymerization of a pyrrole amphiphilic monomer-PPO mixture, previously adsorbed on a glassy carbon electrode, is applied for the direct amperometric response of phenol, 3-chlorophenol and 4-chlorophenol. Furthermore, the detection of 2-chlorophenol, several polychlorophenols and pentachlorophenol is carried out by an inhibition process of the bioelectrode functioning. The mechanism of the bioelectrode inhibition is investigated in terms of enzymatic inhibition and polymer fouling. The capacities of this system for the resolution of mixtures of phenolic pollutants are also explored on the basis of the kinetic behavior of the bioelectrode response.

Possible analytical application of laponite clay modified electrodes

Abstract Laponite clay modified electrodes (LCME) have been used to detect trace amounts of neutral or cationic organometallic substances, including ferrocene (Fc) and cobaltocenium (Cc+), two molecules covalently attached to cobaltocenium, and a molecule labelled by ferrocene (N-amphetaminecarbonylferrocene) as an electroactive organic test species. During an ion-exchange preconcentration step, the cationic species (cobaltocenium derivatives) are collected in the laponite film from their dilute solutions under open-circuit conditions whereas the procationic species (ferrocene derivatives) are collected in their cationic form by applying a positive potential. Quantification of the surface bound cations is then carried out by applying a negative scan using voltammetry or square wave voltammetry. In the case of the two molecules labelled by Cc+, a detection limit of 4 × 10−8 mol l−1 and a linear calibration range from 1 × 10−7 to 2 × 10−5 mol l−1 are obtained reproducibly by using a new LCME for each measurement. Conversely with small redox molecules such as ferrocene and cobaltocenium, the same LCME can be used repeatedly because applying a negative potential leads to the exclusion of the resulting neutral molecule which can be rinsed efficiently from the film.

Immobilization of redox anions in poly(amphiphilic pyrrolylalkylammonium) using a simple and monomer-saving one-step procedure in pure water electrolyte

The pyrrolylalkylammonium tetrafluoroborate monomer 1 can be electropolymerised in aqueous electrolytes when adsorbed on an electrode surface and electroactive bulky anions can be incorporated either in polymer films of 1, or by electropolymerisation of a coating containing the anion along with 1; cyclic voltammetry peak splittings suggest a regular surface arrangement.