Abstracts

Abstract

BIOSENSORS—42 YEARS AND COUNTING by George G. Guilbault, M. Pravda, and M. Kreuzer, Chemistry Department, Sensors Development Research Group, University College Cork, Cork, Ireland and C. K. O'Sullivan, Department of Chemical Engineering, Nanobiotechnology and Bioanalysis Group, Universitat Rovira i Virgili, Tarragona, Spain

ABSTRACT: In this presentation, the entire field of biosensor research and commercial applications will be covered, starting with the beginnings of developments in the 1960s, through 42 years to the present. Especially stressed is the fields of immunosensors, a technique dating back to 1964 and one that forms the most active field if research today. Finally, some of the newer biological sensors are mentioned‐antibody fragments and non‐immunoglobulin ligands.

Analytical Letters, 37(8), 1481–1496, 2004

Abstract

DEVELOPMENT OF A LACCASE‐MODIFIED ELECTRODE FOR AMPEROMETRIC DETECTION OF MONO‐ AND DIPHENOLS. THE INFLUENCE OF ENZYME STORAGE METHOD by Anna Jarosz‐Wilkołazka, Grzegorz Janusz, Elzbieta Malarczyk, and Andrzej Leonowicz, Department of Biochemistry, Maria Curie‐Skłodowska University, Lublin, Poland and Tautgirdas Ruzgas and Lo Gorton, Department of Analytical Chemistry, University of Lund, P.O. Box 124, Lund S‐221 00, Sweden

ABSTRACT: Results are reported for biosensors based on two different preparations of the same enzyme, laccase from Cerrena unicolor, one lyophilized and one stored frozen at −18°C, for monitoring phenolic compounds. The enzyme was adsorbed on graphite electrodes and these were used in a flow through wall jet cell connected to a flow injection set‐up. The electrodes were used at −50 mV vs. Ag|AgCl. The effect of pH, flow rate of the carrier buffer was investigated as well as the operational and storage stability. Biosensors based on the frozen enzyme preparation were shown to be superior for biosensor construction.

Analytical Letters, 37(8), 1497–1513, 2004

Abstract

FLOW INJECTION ANALYSIS OF BENZENE USING AN AMPEROMETRIC BACTERIAL BIOSENSOR by Yvonne H. Lanyon and Ibtisam E. Tothill, Cranfield Biotechnology Centre, Cranfield University, Silsoe, Bedfordshire MK45 4DT, UK and Yvonne H. Lanyon, Giovanna Marrazza, and Marco Mascini, Department of Chemistry, Florence University, Sesto Fiorentino FI, Italy

ABSTRACT: A bacterial biosensor integrated within a flow injection analysis (FIA) system has been developed for the detection of benzene, based on its aerobic catabolism by Pseudomonas putida ML2. P. putida ML2 cells were immobilised between two cellulose acetate membranes and fixed onto a Clark dissolved oxygen electrode. Biosensor responses were investigated with the FIA system, resulting in a linear detection range between 0.01–0.1 mM benzene. A response and baseline recovery time of 6 and 10–15 min, respectively, was obtained. A stable and reproducible sensor response has been found up to 28 days of use based on the same bacterial membrane, and the sensor has shown a high specificity to benzene, with a negligible response to other benzene‐related compounds. Its ease of operation, rapid and sensitive response, and cost‐effective production, demonstrate that the P. putida ML2 biosensor has potential applications for the analysis of samples containing benzene. The optimisation of the biosensor‐flow injection system is described.

Analytical Letters, 37(8), 1515–1528, 2004

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COMBINATION OF GOLD‐MODIFIED ELECTRODE AND α‐AMYLOGLUCOSIDASE FOR SIMULTANEOUS DETERMINATION OF STARCH AND GLUCOSE by Ilhame Bourais and Aziz Amine, Laboratoire des Analyses Chimiques et Biocapteurs, Faculté des Sciences et Techniques, B.P.146, Mohammedia, Morocco and Christopher M. A. Brett, Departamento de Quimica, Universidade de Coimbra, Coimbra, Portugal

ABSTRACT: The electrocatalytic activity of copper‐modified gold electrodes has been investigated for the simultaneous detection of glucose and starch using α‐amyloglucosidase in solution. The amperometric response of glucose at the modified gold electrode was monitored for different copper loadings (0.04, 0.1, 0.2, and 0.3 mg cm⁻²), that of 0.2 mg cm⁻² deposited on the electrode surface being chosen for further investigation. The surface characteristics were confirmed by the electrochemical impedance spectra. The oxidation of glucose and starch was studied by linear sweep voltammetry (LSV) in order to determine the best applied potential for measuring glucose in the presence of starch, a value of +0.4 V vs. SCE being selected. The glucose detection limit at +0.4 V is equal to 0.64 mg L⁻¹ in the absence of starch. The same detection limit was found after adding 200 mg L⁻¹ starch to the cell. The properties of the copper‐deposited films were investigated in 0.15 M NaOH solution for the determination of α‐amyloglucosidase enzyme activity. The enzymatic reaction conditions were optimized. Conversion of starch into glucose was found to be around 89% by using α‐amyloglucosidase (2970 mUI) at 55°C for 30 min.

Analytical Letters, 37(8), 1529–1543, 2004

Abstract

DEVELOPMENT OF AN ELECTROCHEMICAL IMMUNOSENSOR FOR OCHRATOXIN A by Sergio Hugo Alarcón, Laura Micheli, and Giuseppe Palleschi, Dipartimento di Scienze e Tecnologie Chimiche, Università di Roma Tor Vergata, Roma, Italia; Sergio Hugo Alarcón, Departamento de Química Analítica, Facultad de Ciencias Bioquímicas y Farmacéuticas, Universidad Nacional de Rosario, Rosario, Argentina; and Dario Compagnone, Dipartimento di Scienze degli Alimenti, Università di Teramo, Via Spagna, 164023, Mosciano S. Angelo, Teramo, Italia

ABSTRACT: A direct, competitive electrochemical enzyme‐linked immunosorbent assay (ELISA) has been developed for the quantitative determination of ochratoxin A (OTA) using polyclonal antibodies. The assay is carried out on carbon‐based screen printed electrodes (SPE). Optimisation of the ELISA competitive conditions allowed us to realise an assay with improved analytical behaviour compared to the classical spectrophotometric ELISA based assay. The performance was comparable to a published monoclonal based assay. The assay gave a detection limit of 180 pg mL⁻¹ and sensitivity of 6.1 ± 0.1 ng mL⁻¹. The immunosensor was challenged with wine to assess a matrix effect. Recoveries obtained were in the 70–118% range. The method appears to be suitable for OTA contamination screening in food samples.

Analytical Letters, 37(8), 1545–1558, 2004

Abstract

THERMAL INKJET TECHNOLOGY FOR THE MICRODEPOSITION OF BIOLOGICAL MOLECULES AS A VIABLE ROUTE FOR THE REALIZATION OF BIOSENSORS by L. Setti, C. Piana, S. Bonazzi, and D. Frascaro, Department of Industrial and Materials Chemistry, University of Bologna, Viale del Risorgimento 4, 40136 Bologna, Italy; B. Ballarin, Department of Physical and Inorganic Chemistry, University of Bologna, Bologna, Italy; A. Fraleoni-Morgera, Spinner Consortium, c/o Department of Industrial and Materials Chemistry, V. Risorgimento 4, I-40136, Bologna, Italy; and S. Giuliani, Lesepidado Srl, V. G. Dozza 5, I-40139, Bologna, Italy

ABSTRACT: Recent progresses in inkjet printing of parts of biosensors are highlighted, with particular reference to the printing of biologically active molecules. We describe a system constituted by a thermal inkjet printer, adapted to layering a bidimensional array of dots [701 × 701 dots per inch] on solid supports. The printer was used to depose a β‐galactosidase (GAL)‐containing ink on a polyester sheet, with dots obtained from 10 pL drops, each drop containing in turn 6 pg of enzyme. The activity of GAL after the preparation was determined using a colorimetric probe (Brilliant Blue FCF). The activity loss of the microdeposed enzymes was found to be around 15%, showing that the 2 µsec‐lasting thermal shock experienced by the biomolecule into the printhead nozzle affects to a lesser extent the activity of the thermal inkjet deposited enzyme. In conclusion, the most recent findings of our group in this line are depicted, and a view of possible future developments of the “biopolytronics” field is outlined.

Analytical Letters, 37(8), 1559–1570, 2004

Abstract

AFFINITY METHODS TO IMMOBILIZE ACETYLCHOLINESTERASES FOR MANUFACTURING BIOSENSORS by Bogdan Bucur, Silvana Andreescu, and Jean‐Louis Marty, Centre of Phytopharmacy, University of Perpignan, URA 5054, 52 Av. de Villeneuve 66860, Perpignan Cedex, France and Bogdan Bucur and Silvana Andreescu, Faculty of Chemistry, University of Bucharest, Bucharest, Romania

ABSTRACT: Two new affinity methods to immobilise acetylcholinesterase (AChE) onto screen‐printed electrodes (SPE) are described and compared for the fabrication of SPE: one based on metal chelate affinity (MCA) and one based on the Concanavalin A (Con A), a sugar residue binding lectine. The manufacturing and the optimisation procedure for each type of biosensor are discussed with respect to no‐specific binding, functionalisation of the SPE surface and the amount of enzyme used. A linear response range to acetylthiocholine substrate between 10 and 100 µmol L⁻¹ was obtained for Con A sensors and between 1 and 60 µmol L⁻¹ with the MCA sensors. The possibilities to reuse the sensors fabricated using both affinity immobilisation chemistries were also discussed. The optimised sensors were used to study the inhibitory effects of organophosphorus pesticides on immobilised AChE activity. A detection limit of 5 × 10⁻⁷ mol L⁻¹ chlorpyrifos methyl‐oxon (ee AChE sensor) and 2 × 10⁻⁹ mol L⁻¹ paraoxon (dm AChE sensor) was achieved for the sensors with the enzyme attached via Con A and NTA–Ni, respectively.

Analytical Letters, 37(8), 1571–1588, 2004

Abstract

A BI‐ENZYMATIC WHOLE‐CELL ALGAL BIOSENSOR FOR MONITORING WASTE WATER POLLUTANTS by Claude Durrieu, Céline Chouteau, and Lucile Barthet, Ecole Nationale des Travaux Publics de l'Etat, Laboratoire des Sciences de l'Environnement, Rue Maurice Audin, Vaulx‐en‐Velin, France; Céline Chouteau and Jean‐Marc Chovelon, Université Claude Bernard Lyon 1, LACE, CNRS UMR, Villeurbanne, France; and Canh Tran‐Minh, Ecole Nationale Supérieure des Mines de Saint Etienne, SPIN, PC2M, Génie Enzymatique, 158 Cours Faurie, 142023, Saint Etienne Cédex, France

ABSTRACT: Two algal whole cells biosensors are developed to measure specific toxicity of freshwater pollutants. Both optical and conductometric biosensors are based on inhibition of algal alkaline phosphatase (AP) and esterase activities. Chlorella vulgaris cells are immobilised on a membrane placed in front of an optical fiber bundle for optical sensing or deposited on the surface of an electrode for conductometric sensing. Phosphatase activity of the biosensor is strongly inhibited by heavy metal ions (60% loss of activity is obtained after 10 ppb Cd²⁺ and Zn²⁺ with 20 min exposure time), as equally observed with a microplate reader. Inhibition of esterase activity (EA) is actually achieved with organophosphorous pesticides such as methyl paraoxon. The biosensors exhibit a response time of about 5 min. These pollutants can be detected down to 10 ppb after being in contact with the biosensor for 30 min. The biosensor can be used up to 20 days with 90% remaining activity.

Analytical Letters, 37(8), 1589–1599, 2004

Abstract

A SCREEN‐PRINTED, AMPEROMETRIC, BIOSENSOR ARRAY FOR THE DETECTION OF ORGANOPHOSPHATE PESTICIDES BASED ON INHIBITION OF WILD TYPE, AND MUTANT ACETYLCHOLINESTERASES, FROM DROSOPHILA MELANOGASTER by A. Crew, J. P. Hart, and R. Wedge, CRAMSS, Faculty of Applied Sciences, University of the West of England, Coldharbour Lane, Frenchay, Bristol, BS16 1QY, UK; J. L.Marty, Centre de Phytopharmacie, Université de Perpignan, Perpignan Cedex, France; and D. Fournier, Laboratoire de Synthèse et Phytochimie des Molécules d'Intérêt Biologique, Université Paul Sabatier, Toulouse, France

ABSTRACT: Screen‐printed carbon electrodes (SPCEs) modified with cobalt phthalocyanine (CoPC) have been used as base transducers in the construction of amperometric pesticide biosensors. Six individual biosensors were fabricated by depositing wildtype (WT) acetylcholinesterase (AChE) from Drosophila melanogaster or one of five mutant forms (B02, B03, B04, B421, and B65) of this enzyme, onto the surfaces of CoPC‐SPCEs; these constituted the amperometric biosensor array. The enzyme converts acetylthiocholine into its electroactive product thiocholine, which is detected at only 0 V vs. Ag/AgCl at the CoPC‐SPCEs. The measurement step is performed using chronoamperometry. In the presence of an organophosphate (OP) pesticide, the enzyme is inhibited, which leads to a decrease in thiocholine production and a corresponding decrease in anodic current. This decrease is proportional to the logarithm of the pesticide concentration. Calibration studies were performed with the biosensor array using five OPs of interest to the food industry, namely omethoate, malaoxon, dichlorvos, chlorpyrifos‐methyl‐oxon, and pirimiphos‐methyl‐oxon. It was found that different inhibition patterns occurred for the five OPs indicating the possibility of identifying and quantifying these compounds in food samples. It should be added that there was no detrimental affect on the biosensor response from wheat or apple extracts.

Analytical Letters, 37(8), 1601–1610, 2004

Abstract

ENZYME BIOSENSOR FOR TOMATINE DETECTION IN TOMATOES by Sergei V. Dzyadevych, Valentyna N. Arkhypova, Alexey P. Soldatkin, and Anna V. El'skaya, Laboratory of Biomolecular Electronics, Institute of Molecular Biology and Genetics, National Academy of Science of Ukraine, 150 Zabolotnogo St., Kiev 03143, Ukraine and Sergei V. Dzyadevych, Claude Martelet, and Nicole Jaffrezic‐Renault, Ecole Centrale de Lyon, CEGELY UMR CNRS 5005, Ecully Cedex, France

ABSTRACT: A biosensor for detection of tomatine in tomatoes has been developed using pH‐sensitive field effect transistor as transducer and immobilised enzyme butyryl cholinesterase (BuChE) as a biorecognition element. The main analytical characteristics of the biosensor developed were studied for different conditions. The possibility to optimise these working parameters was investigated. By using this biosensor and enzyme inhibition effect, the tomatine can be measured in the concentration range of 0.5–50 µM with a detection limit of 0.2 µM. Tomatine concentrations in different tomato juice samples were determined by such a biosensor, and a good correlation with the known real content was revealed. A high reproducibility and operational stability of the biosensor developed were shown.

Analytical Letters, 37(8), 1611–1624, 2004

Abstract

VOLTAMMETRIC BEHAVIOUR OF CHLOROPHYLL a AT A SCREEN‐PRINTED CARBON ELECTRODE AND ITS POTENTIAL ROLE AS A BIOMARKER FOR MONITORING FAECAL CONTAMINATION by R. M. Pemberton and J. P. Hart, Centre for Research in Analytical, Materials and Sensors Science, Faculty of Applied Sciences, University of the West of England, Coldharbour Lane, Bristol BS16 1QY, UK; and A. Amine, Faculte des Sciences et Techniques, Universite Hassan II, Mohammadia, Morocco

ABSTRACT: Direct cyclic voltammetric determination of Chlorophyll a (Chl a) at a screen‐printed carbon electrode (SPCE) resulted in a single, irreversible anodic oxidation peak at E _p = + 400 mV vs. Ag/AgCl. Electrochemical investigations revealed that Chl a was adsorbing onto the SPCE surface. This adsorption phenomenon allowed the development of a method for Chl a determination, based on medium exchange followed by adsorptive stripping voltammetry (AdSV). The final protocol was optimised with respect to pH of accumulation/measurement buffer, accumulation time, and acetone content of accumulation buffer. Using this protocol, it was possible to determine Chl a in aqueous phosphate buffer over the concentration range 0.014–2.24 µM. This optimised protocol was applied to the determination of Chl a in faeces from dairy cows. The endogenous content of Chl a was calculated to be 15 mg g⁻¹ of dried faecal matter. The mean recovery for the method was 104%, with an overall coefficient of variation of 18.4%. Based on these data, the detection limit for dried faecal matter was 300 µg in 10 mL of simulated teat wash water. This approach demonstrates that the electrochemical detection of Chl a is a potential means of monitoring faecal contamination in the dairy industry.

Analytical Letters, 37(8), 1625–1643, 2004

Abstract

MONOLAYERS OF NATURAL AND RECOMBINANT PHOTOSYSTEM II ON GOLD ELECTRODES—POTENTIALS FOR USE AS BIOSENSORS FOR DETECTION OF HERBICIDES by J. Maly, Department of Biology, University of J.E. Purkyne, Usti nad Labem, Czech Republic; A. Masci and R. Pilloton, ENEA, SP061, Via Anguillarese, 301, 00060 Santa Maria di Galeria, Roma; J. Masojidek, Institute of Microbiology, Academy of Sciences, Trebon, Czech Republic; and M. Sugiura, Department of Biological Chemistry, Osaka Prefecture University, Osaka, Japan

ABSTRACT: Two methods for monolayer immobilisation of photosystem II (PSII) isolated from thermophilic cyanobacteria Synechococcus elongatus and prospects for its use as a biosensor for detection of herbicides are reported: (i) Immobilisation based on recombinant (His)₆‐tagged PSII coupled with nickel‐nitrilotriacetic acid (Ni‐NTA) chelator monolayer on Au electrode. (ii) Immobilisation based on the natural PSII coupled with the protein A‐anti‐D1 antibody modified Au electrode. Here, Cysteamine (CYS)‐self‐assembled monolayer (SAM)‐(NTA)‐PSII monolayers were compared with traditional bovine serum albumin (BSA)‐glutaraldehyde (GA)‐PSII crosslinked gel matrix and better performances of the derived electrochemical biosensors were pointed out. Better diffusion of inhibitors and mediators resulted in improved sensitivity, velocity of the response, and lower I ₅₀ for herbicides.

Analytical Letters, 37(8), 1645–1656, 2004

Abstract

AMPEROMETRIC MEDIATED CARBON NANOTUBE PASTE BIOSENSOR FOR FRUCTOSE DETERMINATION by Riccarda Antiochia, Irma Lavagnini, and Franco Magno, Dipartimento di Chimica Inorganica, Metallorganica ed Analitica, Università di Padova, Via Marzolo 1, I‐35131 Padova, Italy

ABSTRACT: A new mediated carbon nanotube paste (CNTP) amperometric biosensor for fructose is described. The biosensor is formed by a CNTP electrode modified with an electropolymerized film of 3,4‐dihydroxybenzaldehyde (3,4‐DHB) and is based on the activity of a commercial available D‐fructose dehydrogenase (FDH) immobilized on an immobilon membrane placed on the top of the electrode surface. Analytical parameters such as enzyme immobilization, pH, temperature, and probe lifetime were studied and optimized. The biosensor response current was directly proportional to D‐fructose concentration from 5 × 10⁻⁶ to 2 × 10⁻³ mol/L with a detection limit of 1 × 10⁻⁶ mol/L and a good reproducibility (RSD = 1.8%, n = 5). The biosensor was used for the determination of fructose content in three honey samples and validated with a commercial spectrophotometric enzymatic kit.

Analytical Letters, 37(8), 1657–1669, 2004

Abstract

A SIMPLE CONDUCTING POLYMER‐BASED BIOSENSOR FOR THE DETECTION OF ATRAZINE by Mohamed El Kaoutit, Dounia Bouchta, Hanane Zejli, Nisrine Izaoumen, and Khalid R. Temsamani, Chemistry Department, Faculté des Sciences de Tétouan, Unité de Recherche de Bioélectrochimie, Université Abdelmalek Essaâdi, B.P. 2121, M'Hannech II, Tétouan, 93002, Morocco

ABSTRACT: In this paper, we present preliminary results for the preparation and application of a biosensor intended to detect photosynthetic inhibiting herbicides such as atrazine. Our approach is based on the preparation of a glassy carbon electrodes operating at open‐circuit and serving for the immobilization of the enzyme polyphenol oxidase (PPO) during the anodic electropolymerization of polypyrrole (PPy). The enzyme is trapped at the electrode surface during the electrochemical synthesis process. A biological reactor can then be realized. Once the biological reactor (the film at the electrode surface) is prepared, another electrode is used as a redox product detector of PPO catalytic activity. The concentration of atrazine in aqueous solution can be determined, thanks to its inhibitory power toward the catalytic activity of PPO represented by the produced quinone concentration. A long electrode lifetime is achieved, thanks to the well‐known high mechanical stability of the conducting polymer PPy and to the absence of polarization of the first electrode (open‐circuit conditions). The interesting analytical performances and simplicity of fabrication of our biosensor suggests its possible application for photosynthetic inhibiting herbicide monitoring.

Analytical Letters, 37(8), 1671–1681, 2004

Abstract

OPTIMISED BIOSENSORS BASED ON PURIFIED ENZYMES AND ENGINEERED YEASTS: DETECTION OF INHIBITORS OF CHOLINESTERASES ON GRAPES by A. Boni, C. Cremisini, E. Magarò, M. Tosi, W. Vastarella, and R. Pilloton, ENEA, Centro Ricerche Casaccia, SP061, Via Anguillarese 301, I‐00060, Santa Maria di Galeria, Rome, Italy

ABSTRACT: Purified acetyl cholinesterase (AChE) from electric eel or engineered yeasts (Kluyveromyces lactis) expressing cholinesterase activity from rat, were immobilised on a nylon membrane for the measurement of residual cholinesterase activity after inhibition by the organophosphorous insecticide Paraoxon (diethyl p‐nitrophenyl phosphate). Measurement was separately operated after the incubation (inhibition) step. The measurement of the residual enzyme activity was therefore performed in a standardised solution with a choline electrochemical biosensor, without any interference, avoiding the use of protecting selective membranes. Both commercial amperometric sensor and screen‐printed electrodes, produced and optimised in the laboratory, were used. The time consuming incubation step was simultaneously performed on several samples, thus lowering the analysis time per sample. Good limit of detection (LOD) (0.1 µg/L) and reproducibility were obtained for the analysis of paraoxon. A simple procedure for the detection of cholinesterase inhibitors on grapes was then developed. The procedure itself could be further extended to several fruits and vegetables, giving a simple but effective tool to verify the absence of residues of anticholinesterasic insecticides.

Analytical Letters, 37(8), 1683–1699, 2004

Abstract

BIOSENSOR FOR SEVEN SULPHONAMIDES IN DRINKING, GROUND, AND SURFACE WATER WITH DIFFICULT MATRICES by Jens Tschmelak, Michael Kumpf, Guenther Proll, and Guenter Gauglitz, Institute of Physical and Theoretical Chemistry (IPTC), Eberhard‐Karls‐University of Tuebingen, Auf der Morgenstelle 8, D‐72076 Tuebingen, Germany

ABSTRACT: Environmental monitoring of antibiotics and other pharmaceuticals in real water samples with difficult matrices places high demands on chemical analysis. Biosensors have suitable characteristics like their efficiency in a fast, sensitive, and cost‐effective detection of pollutants. In this article, we present a recently developed immunoassay for seven sulphonamides (sulphadiazine, sulphamethoxazole, sulphadimidine, sulphamethizole, sulphadimethoxine, sulphathiazole, and sulphamethoxypyridazine) which can only be detected separately. For the simultaneous determination of multiple sulphonamides in the future we performed measurements with different combinations of binary mixtures. The results of the immunosensor were compared to a mathematical model which was developed in our group. Using an automated biosensor system it was possible for the first time to achieve limits of detection (LOD) below 10 ng L⁻¹ and limits of quantification (LOQ) below 100 ng L⁻¹ without sample pre‐concentration for these sulphonamides. Sulphonamide calibrations with different immobilised analyte derivatives were made in Milli‐Q water. Unstrained spiked and un‐spiked real water samples with complex matrices (drinking, ground, and surface water) were measured. In compliance with the Association of Analytical Communities (AOAC) International most recovery rates obtained were between 70% and 120%. The reproducibility was checked by measuring replica of each sample within independent repetitions. Robustness could be demonstrated by long‐term stability tests of the biosensor surface. These studies show that the biosensor used offers the necessary reproducibility, precision, and robustness required for an analytical method. The measuring data of the binary mixtures show a systematic error compared to the mathematical model at high concentrations of both sulphonamides, because the approximation uses only the standard calibration curves (data of the logistic fit function) as input data. It is also hard to adequately describe the cross‐reactivity and the behaviour of a mixture of polyclonal antibodies.

Analytical Letters, 37(8), 1701–1718, 2004

Abstract

A BIOSENSOR‐BASED METHOD FOR NON‐INVASIVELY MONITORING WILDLIFE REPRODUCTION—THE FIELD VOLE (MICROTUS AGRESTIS) AS A POTENTIAL BIOMARKER OF ENVIRONMENTAL DISRUPTION by G. Caplen and T. T. Mottram, Sensing Group, Silsoe Research Institute Wrest Park, Silsoe, Bedfordshire MK45 4HS, UK; G. Caplen and A. R. Pickard, Zoological Society of London, Reproductive Biology Unit, Regent's Park, London, UK; G. Caplen and S. R. Milligan, Centre for Reproduction, Endocrinology and Diabetes, Kings College London, New Hunts House, Guy's Campus, London Bridge, London, UK; and A. R. Pickard, Medical Research Council, Harwell, Didcot, Oxfordshire, UK

ABSTRACT: Environmental disturbance arising from human activity is known to adversely impact upon biodiversity in many different ways. The use of biomarkers offers an indirect means of detecting and monitoring broad non‐specific exposure to one or more chemical pollutants; however, no biomarker for monitoring the effect of such disruption on terrestrial mammals has yet been validated. In response to the need for a cheap, simple, effective means for detecting environmental disturbance, we propose that monitoring fecundity within a small mammalian (short‐tailed field vole, Microtus agrestis) population via non‐invasive faecal steroid analysis may provide such a biomarker. In this paper, we present the validation of an enzyme‐linked immunosorbent assay (ELISA) and biosensor system currently employed to monitor progesterone levels in bovine milk, for use with faecal extracts. Biosensor technology was found to offer a comparable (P < 0.01), novel and alternative means to traditional ELISA methodology for the measurement of progestagen levels in pregnant vole faecal samples, and as such it provides the potential for future use within the field as an aid to wildlife monitoring programmes.

Analytical Letters, 37(8), 1719–1735, 2004

Abstract

ELECTROCHEMICALLY AIDED SOLID PHASE MICRO‐EXTRACTION OF MERCURY(II) AT A POLY(3‐METHYLTHIOPHENE) MODIFIED GOLD ELECTRODE by H. Zejli, N. Izaoumen, D. Bouchta, M. El Kaoutit, and K. R. Temsamani, Laboratoire de Bioélectrochimie, Département de Chimie, M'Hannech II, Faculté des Sciences de Tétouan, Université Abdelmalek Essaâdi, B.P. 2121, 93002 Tétouan, Morocco

ABSTRACT: A simple approach for increasing the sensitivity and selectivity for the detection of mercury(II) species in water is presented. The technique is based on two steps: (1) micro‐extraction (uptake step) of mercury(II) by simply incubating an electropolymerized poly(3‐methylthiophene) (P3MT) modified gold electrode, at open‐circuit potential conditions, into a solution containing the heavy metal for 30 min and (2) the electrode is transferred from the analyte solution to an electrochemical cell (release step) for successive voltammetric determinations. Surprisingly, cyclic voltammetric measurements showed a first large anodic peak characteristic of oxidation of metallic mercury to form mercury(II) at 0.53 V. The reversed scan, showed a smaller cathodic peak at 0.4 V, suggesting a possible electroless reduction from Hg(II) to metallic mercury during the extraction step probably caused by the heteroatom of P3MT. Under these conditions, differential pulse voltammetry (DPV) measurements performed on the P3MT electrode showed that the anodic peak current exhibit a good linear concentration dependence in the range 10⁻⁸–4 × 10⁻⁶ mol/L. The detection limit was estimated for S/N > 3 to be 10⁻¹⁰ mol/L. The analytical performances of the extraction method has been explored by optimizing the electropolymerization time, pH, and effect of interferences due to other ions. On the other hand, scanning election microscopy–energy dispersive analysis of x‐ray (SEM–EDAX) and electrochemical impedance spectroscopy (EIS) measurements performed on P3MT films confirmed the adsorption of the heavy metal on the polymeric film due to the extraction process.

Analytical Letters, 37(8), 1737–1754, 2004