Disposable potentiometric sensors for monitoring cholinesterase activity (original) (raw)
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Analytical and Bioanalytical Chemistry, 2003
Cholinesterase sensors based on screen-printed electrodes modified with polyaniline, 7,7′,8,8′-tetracyanoquinodimethane (TCNQ), and Prussian blue have been developed and tested for detection of anticholinesterase pesticides in aqueous solution and in spiked grape juice. The influence of enzyme source and detection mode on biosensor performance was explored. It was shown that modification of the electrodes results in significant improvement of their analytical characteristics for pesticide determination. Thus, the slopes of the calibration curves obtained with modified electrodes were increased twofold and the detection limits of the pesticides were reduced by factors of 1.6 to 1.8 in comparison with the use of unmodified transducers. The biosensors developed make it possible to detect down to 2×10−8 mol L−1 chloropyrifos-methyl, 5×10−8 mol L−1 coumaphos, and 8×10−9 mol L−1 carbofuran in aqueous solution and grape juice. The optimal conditions for grape juice pretreatment were determined to diminish interference from the sample matrix.
Mikrochimica Acta, 1995
Plastic disposable choline biosensors based on ruthenized-carbon screen-printed electrodes were prepared and their use for monitoring organophosphorus pesticides and carbamates is described. The presence of 0.5% ruthenium on activated carbon mixed to form a simple graphite-based ink for the working electrode surface increased the sensitivity towards hydrogen peroxide. The choline biosensor is based on such an electrode coupled with choline oxidase immobilized by adsorption and was used to detect the inhibition effect of carbamates and organophosphorus pesticides on acetylcholinesterase. With the optimized procedure described (pH, buffer composition, incubation time, substrate concentration), concentrations of pesticides (Carbofuran) as low as 1 nM could be detected.
Comparative investigation of electrochemical cholinesterase biosensors for pesticide determination
Analytica Chimica Acta, 2000
A number of potentiometric biosensors based on cholinesterases from various sources have been developed and examined for the determination of Co-Ral and Trichlorfon to establish factors affecting the analytical performance of biosensors. Acetylcholinesterase (AChE) from electric eel and butyrylcholinesterase (BChE) from horse serum were immobilised on the surface of antimony electrode and on the commercial membranes (nylon and cellulose nitrate) by treatment with glutaraldehyde in vapours and aqueous solution. The biosensors developed make it possible to determine Trichlorfon and Co-Ral with detection limits 0.01 and 0.02 mg l −1 , respectively.
The use of polyethyleneimine for fabrication of potentiometric cholinesterase biosensors
Talanta, 2002
Potentiometric biosensors based on butyrylcholinesterase are developed by co-reticulation of the enzyme with glutaraldehyde on an electropolymerized polyethyleneimine film at the electrode surface. The BuChE-electrode was tested as biochemical sensor for detection of an organophosphorus pesticide, trichlorfon in liquid, the detection being based on the enzyme inhibition. The enzyme electrode showed a detection limit for trichlorfon below 10 − 7 M.
Talanta, 2000
Screen-printed electrodes coated with the nafion layer have been investigated for cholinesterase biosensor design. The butyrylcholinesterase (ChE) from horse serum was immobilised onto the nafion layer by cross-linking with glutaraldehyde vapours. The biosensors obtained showed better long-term stability and lower working potential in comparison to those obtained with no nafion coating. The sensitivity of a biosensor toward organophosphate pesticides is not affected by the nafion coating. The detection limits were found to be 3.5×10 − 7 M for trichlorfon and 1.5× 10 − 7 M for coumaphos.
Comprehensive Analytical Chemistry, 2007
This review is focussed towards the development of acetylcholinesterase enzymatic based biosensors for the quantification of trace concentrations of highly toxic pesticides via their inhibitory effect on the enzyme. Initial results were obtained using wild-type enzymes which have a broad spectrum of susceptibility to a variety of pesticides. The sensitivity and selectivity of the enzyme activity was improved by development and screening of a wide range of mutant enzymes. Optimal enzymes were then exploited within a range of sensor formats. A range of immobilisation techniques including adsorption based approaches, binding via proteins and entrapment within conducting polymers were all studied. The incorporation of stabilisers and co-factors were utilised to optimise electrode performance and stability-with both planar and microelectrode geometries being developed. Reproducible quantification of pesticides could be obtained at concentrations down to 10-17 M, representing a detection limit hitherto unavailable.
Microchimica Acta, 2010
The present review reports the research carried out during last 9 years on biosensors based on cholinesterase inhibition for nerve agents, organophosphorus and carbammic insecticides, and aflatoxin B 1 detection. Relative applications in environmental and food areas are also reported. Special attention is paid to the optimization of parameters such as enzyme immobilization, substrate concentration, and incubation time in the case of reversible inhibition by aflatoxin B 1 or irreversible inhibition by organophosphorus and carbamic insecticides, and nerve agents in order to optimize and improve the analytical performances of the biosensor. Evaluation of selectivity of the system is also discussed.
Journal of Advanced Science, 2000
A disposable cholinesterase biosensor based on screen-printed electrodes (SPE) was assembled and used to assess the effect of miscible organic solvents on the acetylcholinesterase activity and on the inhibitory effect of organophosphorus pesticides on acetylcholinesterase activity. Acetonitrile, ethanol and DMSO were tested in a range of 0 to 30% mixed with phosphate buffer (0.1M, pH7). With 5% acetonitrile and 10% ethanol, an increase of the recorded current was observed. The addition of 0.2% polyethylenimine to the enzyme preparation, before immobilization, allowed the utilization of 15% acetonitrile without negative effect on the enzyme activity. An inhibition calibration curve was obtained using chlorpyrifosethyl-oxon, a compound widely used for agricultural purposes. The lowest detectable amount was 1 ppb following an incubation time of 10min. The use of 5% acetonitrile and 0.2% polyethylenimine did not interfere with the enzyme-inhibitors interactions. The second part is focused on the evaluation of the activity of several genetically modified acetylcholinesterases obtained from Drosophila melanogaster and their inhibition constant face to the methamediphos. The selection of one of them and its immobilization on a SPE allowed a detection of 1.4 ppb methamediphos.
Analytica Chimica Acta, 2006
In the present paper, a comparative study using Co-phthalocyanine and Prussian Blue-modified screen-printed electrodes, has been performed. Both the electrodes have demonstrated an easiness of preparation together with high sensitivity towards thicoholine (LOD = 5 × 10 −7 and 5 × 10 −6 M for Co-phthalocyanine and Prussian Blue, respectively) with high potentialities for pesticide measurement. Prussian Blue-modified screen-printed electrodes were then selected for successive enzyme immobilization due to their higher operative stability demonstrated in previous works. AChE and BChE enzymes were used and inhibition effect of different pesticides was studied with both the enzymes. AChE-based biosensors have demonstrated a higher sensitivity towards aldicarb (50% inhibition with 50 ppb) and carbaryl (50% inhibition with 85 ppb) while BChE biosensors have shown a higher affinity towards paraoxon (50% inhibition with 4 ppb) and chlorpyrifos-methyl oxon (50% inhibition with 1 ppb). Real samples were also tested in order to evaluate the matrix effect and recovery values comprised between 79 and 123% were obtained.
Biosensors and Bioelectronics, 2005
The dry and wet stability of Drosophila acetylcholinesterase non-covalently immobilized onto polyethyleneimine modified screen-printed carbon electrodes was improved when compared to non-immobilized acetylcholinesterase, and acetylcholinesterase covalently immobilized onto dialdehyde and polyethyleneimine modified electrodes. Stabilizer mixtures were characterized for additional stabilization of acetylcholinesterase during storage in the dry state, with dextran-sulphate/sucrose and polygalacturonic acid/sucrose mixtures proving highly effective for long-term storage of biosensor electrodes.