A preliminary study on electrochemical biosensors for the determination of total cholinesterase inhibitors in strawberries (original) (raw)
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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.
Twenty years research in cholinesterase biosensors: From basic research to practical applications
Biomolecular Engineering, 2006
Over the last decades, cholinesterase (ChE) biosensors have emerged as an ultra sensitive and rapid technique for toxicity analysis in environmental monitoring, food and quality control. These systems have the potential to complement or replace the classical analytical methods by simplifying or eliminating sample preparation protocols and making field testing easier and faster with significant decrease in costs per analysis. Over the years, engineering of more sensitive ChE enzymes, development of more reliable immobilization protocols and progress in the area of microelectronics could allow ChE biosensors to be competitive for field analysis and extend their applications to multianalyte screening, development of small, portable instrumentations for rapid toxicity testing, and detectors in chromatographic systems. In this paper, we will review the research efforts over the last 20 years in fabricating AChE biosensors and the recent trends and challenges encounter once the sensor is used outside research laboratory for in situ real sample applications. The review will discuss the generations of cholinesterase sensors with their advantages and limitations, the existing electrode configurations and fabrication techniques and their applications for toxicity monitoring. We will focus on low-cost electrochemical sensors and the approaches used for enzyme immobilization. Recent works for achieving high sensitivity and selectivity are also discussed. #
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.
Biosensors and Bioelectronics, 2014
The work presented here describes a novel, easy and low-cost method of fabrication of a highly sensitive acetylcholinesterase biosensor and its application to detect organophosphate and organocarbamate pesticides. Acetylcholinesterase was electro-immobilized into a thick conducting layer of polypyrrole. Porcine skin gelatin and gluteraldehyde mixture was used for stabilizing the system. Acetylthiocholine chloride was used as the substrate. Polypyrrole catalyzed the electrochemical oxidation of thiocholine and promoted the electron transfer, thus lowering the oxidation potential and increasing the detection sensitivity. Electro oxidation of thiocholine in polypyrrole matrix occurred at 0.1 V under low potential scan rate. The thiocholine sensitivity of the electrode was found to be 143 mA/M. The sensor was applied to detect the sample organophosphate pesticide ethylparaoxon and organocarbamate pesticide carbofuran. The detection limit for paraoxon was found to be 1.1 ppb and that for carbofuran is 0.12 ppb. The sensor showed good intra and inter state precision with relative standard deviation (RSD) 0.742% and 6.56% respectively. Both dry and wet storage stability were studied. The sensor stored at 0 1C in dry condition had a good storage stability retaining 70% of its original activity for 4 months. During wet storage, the activity decrease followed the same trend, however, the operational stability at the end of the storage period was found to be less compared to the dry storage case. The developed biosensor is as a promising new tool for analysis of cholinesterase inhibitors.
Amperometric flow-through biosensor for the determination of cholinesterase inhibitors
Analytica Chimica Acta, 1999
An amperometric flow-through biosensor for the determination of pesticides is proposed. It is based on the inhibition of the acetyl cholinesterase-catalysed hydrolysis of 4-aminophenylacetate. The calibration graphs were linear from 5.0 X lo-' to 1.0 x lop5 M and 5.0 X lo-' to 5.0 X lo-' M for paroxon and carbaryl, respectively. The detection limit (5% of inhibition) was 1.0 X lo-' M pesticide. The relative standard deviations (R.S.D.) (n = 5) were 3.7% for 4.0 X lop5 M and 4.0% for 8.0 X 10ph M for either carbaryl or paroxon. Electroactive species such as uric and ascorbic acid and benzafdehyde that could be oxidized at the same potential as 4-aminophenol, do not interfere. However, compounds which strongly absorb onto the electrode surface, such as bovine serum albumin (BSA) and surfactants capable of denaturing the enzyme activity, cause an interference. The stability of the sensor was high and even after repetitive use for one month the electrode retained 90% of its original activity. The determination of carbaryl and paroxon was carried out in lagoon water and kiwi fruits. The lowest concentration of pesticide determined in lagoon water was 1.0 X lo-' M for paroxon and 4.0 X lo-' M for carbaryl. K~ywor~st Biosensors; Flow system; Ampcrometry; Pesticides 0003-2670/95/$09.50 0 1995 Elscvier Science B.V. All rights reserved SSDI 0003-2670(94)00529-X
Chemico-Biological Interactions, 2010
The method for automatic continual monitoring of acetylcholinesterase (AChE) activity in biological material is described. It is based on flexible system of plastic pipes mixing samples of biological material with reagents for enzyme determination; reaction product penetrates through the semipermeable membrane and it is spectrophotometrically determined (Ellman's method). It consists of sampling (either in vitro or in vivo), adding the substrate and flowing to dialyzer; reaction product (thiocholine) is dialyzed and mixed with 5,5 -dithio-bis-2-nitrobenzoic acid (DTNB) transported to flow spectrophotometer. Flowing of all materials is realised using peristaltic pump. The method was validated: time for optimal hydratation of the cellophane membrane; type of the membrane; type of dialyzer; conditions for optimal permeation of reaction components; optimization of substrate and DTNB concentrations (linear dependence); efficacy of peristaltic pump; calibration of analytes after permeation through the membrane; excluding of the blood permeation through the membrane. Some examples of the evaluation of the effects of AChE inhibitors are described. It was demonstrated very good uniformity of peaks representing the enzyme activity (good reproducibility); time dependence of AChE inhibition caused by VX in vitro in the rat blood allowing to determine the half life of inhibition and thus, bimolecular rate constants of inhibition; reactivation of inhibited AChE by some reactivators, and continual monitoring of the activity in the whole blood in vivo in intact and VX-intoxicated rats. The method is simple and not expensive, allowing automatic determination of AChE activity in discrete or continual samples in vitro or in vivo. It will be evaluated for further research of cholinesterase inhibitors.
Biosensors and Bioelectronics, 1990
Acetylcholine esterase electrodes, based on glass, Pd/pdO and Ir/IrOz electrodes as pH sensor, using the immobilized acetylcholine esterase in acrylamide-methacrylamide hydrazides prepolymer are reported and compared. New data on the analysis of nicotine, fluoride ion, and some otganophosphorus compounds are reported using the present AChE sensor based on the inhibition of the immobilized acetylcholine estemse. Reactivation of immobilized AChE afrer inhibition with reversible inhibitor, i.e. nicotine and fluoride ion is carried out using a mixture of working bu#er and acetylcholine, whereas reactivation afrer inhibition with inwersible inhibitor, i.e. organophosphorus compounds is carried out using a mixture of acetylcholine and pyridine-2-aldoxime methiodide (PAM). The detection limits for the nicotine and fluoride ion are found to be IO-'M whereas for paraoxon, methyl parathion and malathion are found to be 10m9~ and 10-'"M.
Determination of binary pesticide mixtures by an acetylcholinesterase–choline oxidase biosensor
Biosensors and Bioelectronics, 2004
In this study, acetylcholinesterase (AChE) and choline oxidase (ChO) were co-immobilized on poly(2-hydroxyethyl methacrylate) (pHEMA) membranes to construct a biosensor for the detection of anti-cholinesterase compounds. pHEMA membranes were prepared with the addition of SnCl 4 to achieve the desired porosity. Immobilization of the enzymes was done by surface attachment via epichlorohydrin (Epi) and Cibacron Blue F3G-A (CB) activation. Enzyme immobilized membrane was used in the detection of anti-cholinesterase activity of aldicarb (AS), carbofuran (CF) and carbaryl (CL), as well as two mixtures, (AS + CF) and (AS + CL). The total anti-cholinesterase activity of binary pesticide mixtures was found to be lower than the sum of the individual inhibition values.
Disposable potentiometric sensors for monitoring cholinesterase activity
Talanta, 2010
A highly sensitive disposable screen-printed butyrylcholine (BuCh) potentiometric sensor, based on heptakis (2,3,6-tri-o-methyl)--cyclodextrin (-CD) as ionophore, was developed for butyrylcholinesterase (BuChE) activity monitoring. The proposed sensors have been characterized and optimized according to the constituents of homemade printing carbon ink including -CD, anionic sites, and plasticizer. The fabricated sensor showed Nernstian responses from 10 −6 to 10 −2 mol L −1 with detection limit of 8 × 10 −7 mol L −1 , fast response time (1.6 s) and adequate shelf-life (6 months). Improved selectivity towards BuCh with minimal interference from choline (Ch) was achieved and the sensor was used for determination of 0.06-1.25 U mL −1 BuChE. The developed disposable sensors have been successfully applied for real-time intoxication monitoring through assaying cholinesterases (ChEs) activity in human serum. Determination of organophosphate pesticide was conducted by measuring their inhibition of BuChE with successful assaying of malathion in insecticide samples with high accuracy and precision.