RESUMEN
In the presented study, an efficient and fast analytical method was developed for the determination of parathion ethyl as sarin simulant by gas chromatography-mass spectrometry (GC-MS). Dispersive solid phase extraction (DSPE) was performed to concentrate parathion ethyl from soil, plant and water samples. Reduced graphene oxide-iron (II, III) oxide (rGO-Fe3O4) nanocomposite was used as an adsorbent to collect the target analyte from the aqueous sample solutions. After the optimization of extraction/preconcentration parameters, optimum conditions for adsorbent amount, eluent type, mixing type/period, eluent volume and initial sample volume were determined as 15 mg, acetonitrile, vortex/30 s, 100 µL and 10 mL, respectively. Under the optimum conditions, analytical performance of the developed DSPE-GC-MS method was evaluated in terms of limit of detection (LOD), limit of quantitation (LOQ) and dynamic range. Dynamic range, LOD and LOQ values were figured out to be 0.94-235.15 µg/kg, 0.41 µg/kg and 1.36 µg/kg (mass based), respectively. Satisfactory percent recovery results (90.3-125% for soil, 93.5-108.7% for plant, 88.5-112.9% for tap water) were achieved for soil, plant and tap water samples which proved the accuracy and applicability of the developed method. It is predicted that the DSPE-GC-MS method can be accurately used for the detection of sarin in soil, plant and water samples taken from war territories.
Asunto(s)
Cromatografía de Gases y Espectrometría de Masas , Sarín , Contaminantes del Suelo , Suelo , Extracción en Fase Sólida , Contaminantes Químicos del Agua , Extracción en Fase Sólida/métodos , Cromatografía de Gases y Espectrometría de Masas/métodos , Sarín/análisis , Contaminantes del Suelo/análisis , Suelo/química , Contaminantes Químicos del Agua/análisis , Monitoreo del Ambiente/métodos , Paratión/análisis , Agentes Nerviosos/análisis , Plantas/química , Límite de Detección , Grafito/químicaRESUMEN
Parathion is one of organophosphorus pesticide, which has been prohibited in agricultural products due to its high toxicity to human beings. However, there are still abuse cases for profit in agricultural production. Hence, we established nanobodies-based colloidal gold immunochromatographic assay (GICA) in which nanobodies (Nbs) as an excellent recognition element, greatly improving the stability and sensitivity of ICA. Under the optimal conditions, the developed Nbs-based GICA showed a cut-off value of 50 ng/mL for visual judgment and a half-inhibitory concentration (IC50) of 2.39 ng/mL for quantitative detection. The limit of detection (LOD) was as low as 0.15 ng/mL which was significantly 50-fold higher sensitivity than the commercial mAb-ICA. Additionally, this method exhibited good recoveries for the detection of cabbage, cucumber, and orange samples and excellent correlation with the UPLC-MS/MS method. The results showed that this method developed in this work based on nanobody can be used in practical detection of parathion in foods and nanobody is novel prospective antibody resource for immunoassays of chemical contaminants.
Asunto(s)
Cromatografía de Afinidad , Oro Coloide , Paratión , Anticuerpos de Dominio Único , Anticuerpos de Dominio Único/inmunología , Anticuerpos de Dominio Único/química , Oro Coloide/química , Paratión/análisis , Cromatografía de Afinidad/métodos , Inmunoensayo/métodos , Límite de Detección , Contaminación de Alimentos/análisisRESUMEN
Herein, we developed a method coupling TLC and enzyme inhibition principles to rapidly detect OPs (dichlorvos, paraoxon and parathion). After the removal of the organic solvent from the samples using TLC and paper-based chips, the enzyme was added to the detection system. The results showed that the current method effectively reduced the effects of solvents on enzyme behavior. Moreover, the pigments could be successfully retained on TLC with 40% ddH2O/ACN solution (v/v) as a developing solvent. Additionally, the detection limits (LODs) were 0.002 µg/mL for dichlorvos, 0.006 µg/mL for paraoxon, and 0.003 µg/mL for parathion. Finally, the method was applied to spiked cabbage, cucumber, and spinach and showed good average recoveries ranging between 70.22% and 119.79%. These results showed that this paper-based chip had high sensitivity, precleaning, and elimination of organic solvent properties. Furthermore, it provides a valuable idea for sample pretreatment and rapid determination of pesticide residues in food.
Asunto(s)
Paratión , Residuos de Plaguicidas , Plaguicidas , Plaguicidas/análisis , Diclorvos/análisis , Cromatografía en Capa Delgada , Paraoxon/análisis , Residuos de Plaguicidas/análisis , Paratión/análisis , SolventesRESUMEN
Pesticide residues in radishes can induce serious health hazards, especially in children and toddlers. In order to assess potential health risk from pesticide residues in radishes, a total of 26 pesticides were evaluated by gas chromatography with mass spectrometry in 1690 samples, which were collected from the year 2016 to 2019 in Shandong Province of China. All the 26 pesticide residues were detected in 752 radish samples (44.50%), but only 221 samples (13.08%) contained detectable pesticide residues, which are above the maximum residue limits (MRLs). Multiple residues with two to nine pesticides were present in 5.09% (86 out of 1690) of samples. Hazard quotient (HQ) and the cumulative risk index were far below 100, while percentage value of acute reference dose (%ARfD) of triazophos exceeded 100 for adults, children, and toddlers. The %ARfD value for carbofuran, aldicarb, monocrotophos, and parathion was over 100 for toddlers. From the perspective of public health, the occurrence of pesticide residues in radishes could not pose a serious health risk problem, but the acute health risk should be paid more attention, especially to toddlers. It is recommended to make strict regulations on the management of pesticide residues and human health risk assessment about pesticide residues.
Asunto(s)
Carbofurano , Monocrotofos , Paratión , Residuos de Plaguicidas , Plaguicidas , Raphanus , Adulto , Humanos , Residuos de Plaguicidas/análisis , Carbofurano/análisis , Contaminación de Alimentos/análisis , Aldicarb/análisis , Monocrotofos/análisis , Cromatografía de Gases y Espectrometría de Masas , Medición de Riesgo , Plaguicidas/análisis , Paratión/análisisRESUMEN
Organophosphate pesticides (OPs) are often used as insecticides and acaricides in agriculture, thus improving yields. OP residues may pose a serious threat, duetoinhibitionof the enzymeacetylcholinesterase(AChE). Therefore, a competitive bio-barcode immunoassay was designed for simultaneous quantification of organophosphate pesticide residues using AuNP signal amplification technology and Au@Pt catalysis. The AuNP probes were labelled with antibodies and corresponding bio-barcodes (ssDNAs), MNP probes coated with ovalbumin pesticide haptens and Au@Pt probes functionalized with the complementary ssDNAs were then prepared. Subsequently, pesticides competed with MNP probes to bind the AuNP probes. The recoveries of the developed assay were ranged from 71.26 to 117.47% with RSDs from 2.52 to 14.52%. The LODs were 9.88, 3.91, and 1.47 ng·kg-1, for parathion, triazophos, and chlorpyrifos, respectively. The assay was closely correlated with the data obtained from LC-MS/MS. Therefore, the developed method has the potential to be used as an alternative approach for detection of multiple pesticides.
Asunto(s)
Contaminación de Alimentos/análisis , Inmunoensayo/métodos , Nanopartículas del Metal/química , Residuos de Plaguicidas/análisis , Catálisis , Cloropirifos/análisis , Cromatografía Liquida , Análisis de los Alimentos/métodos , Oro/química , Inmunoensayo/instrumentación , Límite de Detección , Compuestos Organofosforados/análisis , Organotiofosfatos/análisis , Oxazinas/química , Paratión/análisis , Platino (Metal)/química , Espectrometría de Masas en Tándem , Triazoles/análisisRESUMEN
Herein, we developed a multi-analyte fluorescence immunoassay for detection of three organophosphate pesticides (triazophos, parathion, and chlorpyrifos) in various agro-products (rice, wheat, cucumber, cabbage, and apple) using fluorescently labeled oligonucleotide and gold nanoparticle (AuNP) signal amplification technology. The AuNP probes for the three analytes were constructed by simultaneously modifying the corresponding antibodies and fluorescently labeled oligonucleotides on the probe surface. Three fluorophores (6-FAM, Cy3, and Texas red) with high fluorescence intensity and little overlap of excitation/emission wavelengths were selected. The method showed satisfactory linearity for triazophos, parathion, and chlorpyrifos in the ranges of 0.01-20, 0.05-50, and 0.5-1000 µg/L, respectively. For the 3 analytes, the limits of detection (LODs) were 0.007, 0.009, and 0.087 µg/L, respectively. The average recoveries were 77.7-113.6%, with relative standard deviations (RSDs) of 7.1-17.1% in various food matrices. The proposed method offers great potential in food safety surveillance, and could be used as well as a reference for multi-residue analysis of other small-molecule contaminants.
Asunto(s)
Oro/química , Insecticidas/análisis , Nanopartículas del Metal/química , Oligonucleótidos/química , Cloropirifos/análisis , Fluorescencia , Análisis de los Alimentos , Inmunoensayo/métodos , Límite de Detección , Organotiofosfatos/análisis , Paratión/análisis , Plaguicidas/análisis , Triazoles/análisisRESUMEN
A competitive sensitive bio-barcode immunoassay based on bimetallic nanozyme (Au@Pt: gold@platinum) catalysis has been designed for the detection of the pesticide parathion. Gold nanoparticles (AuNPs) were modified with single-stranded thiol oligonucleotides (ssDNAs) and monoclonal antibodies (mAbs) to form AuNP probes; magnetic nanoparticles (MNPs) were coated with ovalbumin (OVA)-parathion haptens as MNP probes, and bimetallic nanozyme (Au@Pt) nanoparticles functionalized with the complementary thiolated ssDNA were used as Au@Pt probes. The Au@Pt probes reacted with the AuNP probes through complementary base pairing. Further, parathion competed with MNP probes to bind the mAbs on the AuNP probes. Finally, the complex system was separated by a magnetic field. The released Au@Pt probes catalyzed a chromogenic system consisting of teramethylbenzidine (TMB). The bimetallic nanozyme-based bio-barcode immunoassay was performed on rice, pear, apple, and cabbage samples to verify the feasibility of the method. The immunoassay exhibited a linear response from 0.01 to 40 µg·kg-1, and the limit of detection (LOD) was 2.13 × 10-3 µg·kg-1. The recoveries and relative standard deviations (RSDs) ranged from 73.12 to 116.29% and 5.59 to 10.87%, respectively. The method was found to correlate well with data obtained by liquid chromatography-tandem mass spectrometry (LC-MS/MS). In conclusion, this method exhibits potential as a sensitive alternative method for the detection of a variety of pesticides, ensuring the safety of fruits and vegetables in agriculture.
Asunto(s)
Inmunoensayo/métodos , Paratión/análisis , Plaguicidas/análisis , Catálisis , Contaminación de Alimentos/análisis , Frutas/química , Oro/química , Inmunoensayo/instrumentación , Límite de Detección , Nanopartículas del Metal/química , Platino (Metal)/química , Verduras/químicaRESUMEN
A competitive bio-barcode immunoassay is described for the trace detection of parathion in water, pear, cabbage, and rice samples. It is based on amplification by platinum nanoparticle acting as a nanozyme. Gold nanoparticles (AuNPs) were modified with (a) monoclonal antibodies (mAbs) against parathion, and (b) thiolated single-stranded DNA (ssDNA) oligonucleotides. Magnetic nanoparticles (MNPs) were functionalized with ovalbumin coupled with parathion hapten. Parathion and its hapten compete with mAbs on the surface of the AuNPs. Subsequently, the platinum nanoparticles (PtNPs) probe, which was functionalized with the complementary thiolated ssDNA (C-ssDNA), was added to the reaction mixture for the detection of parathion. The signal was catalytically amplified by coupling with platinum nanozyme using teramethylbenzidine and H2O2 as the chromogenic system. The immunoassay has a linear range that extends from 0.01-50 µg·L-1, and the limit of detection is 2.0 × 10-3 µg·L-1. The recoveries and relative standard deviations (RSDs) ranged from 91.1-114.4% and 3.6-15.8%, respectively. The method correlates well with data obtained by gas chromatography-tandem mass spectrometry (GC-MS/MS). Graphical abstract The parathion and the magnetic nanoparticles (MNPs) labelled with hapten-OVA competitively reacted to AuNPs modified with mAbs and thiolated DNA for the detection of parathion. The signal was catalyzed by platinum nanozyme. The limit of detection for parathion is 2.0 ng·L-1.
Asunto(s)
Inmunoensayo/métodos , Nanopartículas del Metal/química , Paratión/análisis , Anticuerpos Monoclonales/inmunología , Bencidinas/química , Brassica/química , Catálisis , Colorimetría/métodos , Oro/química , Peróxido de Hidrógeno/química , Límite de Detección , Oryza/química , Paratión/inmunología , Residuos de Plaguicidas/análisis , Residuos de Plaguicidas/inmunología , Platino (Metal)/química , Pyrus/química , Agua/análisis , Contaminantes Químicos del Agua/análisis , Contaminantes Químicos del Agua/inmunologíaRESUMEN
A heavy chain variable fragment of heavy chain only antibodies derived from camelids termed VHH shows beneficial characteristics for immunoassay in terms of high sensitivity, outstanding stability and ease in expression. In the present study, we isolated six VHHs from phage display library against parathion, which is a widely used organophosphorus pesticide with high toxicity and persistence. One of six selected VHHs named VHH9, showed highest specificity and superior thermo-stability. A VHH9-alkaline phosphatase (AP) fusion was constructed and used to establish a one-step direct competitive fluorescence enzyme immunoassay (dc-FEIA) with a half maximal inhibitory concentration (IC50) of 1.6 ng/mL and a limit of detection of 0.2 ng/mL which was 4-fold or 3-fold higher sensitivity than direct competitive enzyme-linked immunoassay (dc-ELISA) and indirect competitive enzyme-linked immunoassay (ic-ELISA) for parathion. Furthermore, our assay indicated a 50% reduction on operation time compared with the ic-ELISA method. The presented immunoassay was validated with spiked Chinese cabbage, cucumber, and lettuce samples, and confirmed by UPLC-MS/MS. The results indicated that the VHH-AP-based dc-FEIA is a reproducible detection assay for parathion residues in vegetable samples.
Asunto(s)
Paratión/análisis , Residuos de Plaguicidas/análisis , Proteínas Recombinantes de Fusión/inmunología , Anticuerpos de Dominio Único/inmunología , Fosfatasa Alcalina/genética , Animales , Secuencia de Bases , Benzotiazoles/química , Brassica/química , Camelus , Cucumis sativus/química , Fluorescencia , Colorantes Fluorescentes/química , Técnicas para Inmunoenzimas/métodos , Lactuca/química , Límite de Detección , Masculino , Paratión/inmunología , Residuos de Plaguicidas/inmunología , Proteínas Recombinantes de Fusión/genética , Sensibilidad y Especificidad , Anticuerpos de Dominio Único/genéticaRESUMEN
The applicability of compound-specific isotope analysis (CSIA) for assessing in situ hydrolysis of parathion was investigated in a contaminated aquifer at a former pesticide wastes landfill site. Stable isotope analysis of parathion extracted from groundwater taken from different monitoring wells revealed a maximum enrichment in carbon isotope ratio of +4.9 compared to the source of parathion, providing evidence that in situ hydrolysis took place. Calculations based on the Rayleigh-equation approach indicated that the natural attenuation of parathion was up to 8.6% by hydrolysis under neutral and acidic conditions. In degradation experiments with aerobic and anaerobic parathion-degrading microbes, no carbon and hydrogen isotope fractionation of parathion were observed. For the first time, CSIA has been applied for the exclusive assessment of the hydrolysis of phosphorothioate-containing organophosphorus pesticides at a contaminated field site.
Asunto(s)
Isótopos de Carbono/análisis , Agua Subterránea/análisis , Paratión/análisis , Plaguicidas/análisis , Contaminantes Químicos del Agua/análisis , Biodegradación Ambiental , Dinamarca , Agua Subterránea/química , Hidrógeno/análisis , Concentración de Iones de Hidrógeno , Hidrólisis , Paratión/química , Paratión/metabolismo , Plaguicidas/química , Plaguicidas/metabolismo , Contaminantes Químicos del Agua/química , Contaminantes Químicos del Agua/metabolismoRESUMEN
Nanozyme-based electrochemical sensors have attracted much attention because of their low cost, sensitivity and remarkable stability under extensive environmental and industrial conditions. Interestingly, the physical characteristics of the nanomaterials in terms of size, shape, composition, surface area and porosity dominate the electrochemical processes at electrode surfaces. Herein, we explore nickel oxide nanoplatelets (NPs) modified screen-printed electrode-based nanozyme sensors that displays high electrochemical activity including stability, sensitivity, selectivity and applicability for organophosphate pesticide (Parathion) determination. Differential pulse voltammogram of NiO-SPE in presence of parathion showed a characteristic peak current at -1.0â¯V (vs. Ag/AgCl). The NiO-SPE platform allows determination of parathion over the concentration range of 0.1-30⯵M with a limit of detection (LOD) of 0.024⯵M. The sensing platform is found to detect parathion of interferences without compromising the sensitivity of the sensor. Such interesting features offer a sensitive determination of parathion in water, urine and vegetable samples.
Asunto(s)
Técnicas Electroquímicas/métodos , Electrodos , Insecticidas/análisis , Paratión/análisis , Técnicas Biosensibles , Técnicas Electroquímicas/instrumentación , Contaminación de Alimentos/análisis , Humanos , Insecticidas/orina , Límite de Detección , Nanoestructuras/química , Níquel/química , Paratión/orina , Verduras , Contaminantes Químicos del Agua/análisisRESUMEN
The chemiluminescence enzyme immunoassay (CLEIA) method responds differently to various sample matrices because of the matrix effect. In this work, the CLEIA method was coupled with molecularly imprinted polymers (MIPs) synthesized by precipitation polymerization to study the matrix effect. The sample recoveries ranged from 72.62% to 121.89%, with a relative standard deviation (RSD) of 3.74-18.14%.The ratio of the sample matrix-matched standard curve slope rate to the solvent standard curve slope was 1.21, 1.12, 1.17, and 0.85 for apple, rice, orange and cabbage in samples pretreated with the mixture of PSA and C18. However, the ratio of sample (apple, rice, orange, and cabbage) matrix-matched standard-MIPs curve slope rate to the solvent standard curve was 1.05, 0.92, 1.09, and 1.05 in samples pretreated with MIPs, respectively. The results demonstrated that the matrices of the samples greatly interfered with the detection of parathion residues by CLEIA. The MIPs bound specifically to the parathion in the samples and eliminated the matrix interference effect. Therefore, the CLEIA method have successfully applied MIPs in sample pretreatment to eliminate matrix interference effects and provided a new sensitive assay for agro-products.
Asunto(s)
Técnicas para Inmunoenzimas/métodos , Mediciones Luminiscentes/métodos , Impresión Molecular/métodos , Paratión/análisis , Paratión/aislamiento & purificación , Polímeros/química , Extracción en Fase Sólida/métodos , Brassica/química , Citrus sinensis/química , Malus/química , Oryza/química , Paratión/químicaRESUMEN
BACKGROUND: Biosensor-based detection provides a rapid and low-cost alternative to conventional analytical methods for revealing the presence of the contaminants in water as well as solid matrices. Although important to be detected, small analytes (few hundreds of Daltons) are an issue in biosensing since the signal they induce in the transducer, and specifically in a Quartz-Crystal Microbalance, is undetectable. A pesticide like parathion (M = 292 Da) is a typical example of contaminant for which a signal amplification procedure is desirable. METHODS/FINDINGS: The ballasting of the analyte by gold nanoparticles has been already applied to heavy target as proteins or bacteria to improve the limit of detection. In this paper, we extend the application of such a method to small analytes by showing that once the working surface of a Quartz-Crystal Microbalance (QCM) has been properly functionalized, a limit of detection lower than 1 ppb is reached for parathion. The effective surface functionalization is achieved by immobilizing antibodies upright oriented on the QCM gold surface by a simple photochemical technique (Photonic Immobilization Technique, PIT) based on the UV irradiation of the antibodies, whereas a simple protocol provided by the manufacturer is applied to functionalize the gold nanoparticles. Thus, in a non-competitive approach, the small analyte is made detectable by weighing it down through a "sandwich protocol" with a second antibody tethered to heavy gold nanoparticles. The immunosensor has been proved to be effective against the parathion while showing no cross reaction when a mixture of compounds very similar to parathion is analyzed. CONCLUSION/SIGNIFICANCE: The immunosensor described in this paper can be easily applied to any small molecule for which polyclonal antibodies are available since both the functionalization procedure of the QCM probe surface and gold nanoparticle can be applied to any IgG, thereby making our device of general application in terms of target analyte.
Asunto(s)
Anticuerpos Inmovilizados , Técnicas Biosensibles , Nanopartículas del Metal/química , Paratión/análisis , Plaguicidas/análisis , Tecnicas de Microbalanza del Cristal de Cuarzo , Adsorción , Anticuerpos Inmovilizados/metabolismo , Anticuerpos Inmovilizados/farmacología , Especificidad de Anticuerpos , Técnicas Biosensibles/instrumentación , Técnicas Biosensibles/métodos , Oro/química , Límite de Detección , Paratión/aislamiento & purificación , Plaguicidas/aislamiento & purificación , Cuarzo/química , Tecnicas de Microbalanza del Cristal de Cuarzo/instrumentación , Tecnicas de Microbalanza del Cristal de Cuarzo/métodosRESUMEN
The widespread use of pesticides has immense effect on increased crop productions. However, they are also responsible for posing detrimental health hazards and/or for contaminating the environment with chemical residues. A routine and an on-field detection of pesticide residues in different food, water, and soil samples has become a need of the hour for which biosensors can offer a viable alternative. The present work reports a functionalized graphene quantum dot (GQD) based screen printed electrochemical immunosensor for the detection of parathion. The application of GQDs has permitted the realization of a sensitive, robust, and reproducible sensor unlike those carried out earlier for the similar purposes. This immunosensor exhibited a dynamic linear response for parathion within the range of 0.01-106 ng/L with a very low detection limit of 46 pg/L. According to the analysis of potential interferences, the proposed sensor was specifically detecting parathion even in the presence of its metabolite, paraoxon. The investigations of the proposed sensing approach with respect to stability, response reproducibility, and regeneration have fully supported its potential practical applicability.
Asunto(s)
Anticuerpos Inmovilizados/química , Técnicas Biosensibles , Técnicas Electroquímicas/métodos , Grafito/química , Insecticidas/análisis , Paratión/análisis , Impresión/métodos , Puntos Cuánticos , Humanos , Límite de Detección , Impresión/instrumentaciónRESUMEN
A novel biosensor for rapid, sensitive and selective monitoring of p-nitrophenyl substituted organophosphate pesticides (OPs) in aqueous system was developed using a functional nanocomposite which consists of elastin-like-polypeptide-organophosphate hydrolase (ELP-OPH), bovine serum albumin (BSA), titanium dioxide nanofibers (TiO2NFs) and carboxylic acid functionalized multi-walled carbon nanotubes (c-MWCNTs). ELP-OPH was simply purified from genetically engineered Escherichia coli based on the unique phase transition of ELP and thus served as biocatalyst for OPs, while BSA was used to stabilize OPH activity in the nanocomposite. TiO2NFs was employed to enrich organophosphates in the nanocomposite due to its strong affinity with phosphoric group in OPs, while c-MWCNTs was used to enhance the electron transfer in the amperometric detection as well as for covalent immobilization of ELP-OPH. ELP-OPH/BSA/TiO2NFs/c-MWCNTs nanocomposite were systematically characterized using field emission scanning electron microscopy (SEM), Raman spectra, Fourier Transform infrared spectroscopy (FTIR) and X-ray Diffraction (XRD). Under the optimized operating conditions, the ELP-OPH/BSA/TiO2NFs/c-MWCNTs based biosensor for OPs shows a wide linear range, a fast response (less than 5s) and limits of detection (S/N=3) as low as 12nM and 10nM for methyl parathion and parathion, respectively. Such excellent sensing performance can be attributed to the synergistic effects of the individual components in the nanocomposite. Its further application for selectively monitoring OPs compounds spiked in lake water samples was also demonstrated with good accuracy. These features indicate that the developed nanocomposite offers an excellent biosensing platform for rapid, sensitive and selective detection of organophosphates compounds.
Asunto(s)
Técnicas Biosensibles/métodos , Nanofibras/química , Nanotubos de Carbono/química , Organofosfatos/análisis , Plaguicidas/análisis , Titanio/química , Contaminantes Químicos del Agua/análisis , Animales , Bovinos , Elastina/química , Elastina/genética , Técnicas Electroquímicas/métodos , Escherichia coli/genética , Expresión Génica , Ingeniería Genética , Lagos/análisis , Metil Paratión/análisis , Nanofibras/ultraestructura , Nanotubos de Carbono/ultraestructura , Paratión/análisis , Péptidos/química , Péptidos/genética , Monoéster Fosfórico Hidrolasas/química , Monoéster Fosfórico Hidrolasas/genética , Albúmina Sérica Bovina/químicaRESUMEN
Due to indiscriminate use of pesticides, there is a growing need to develop sensors that can sensitively detect the trace amount of pesticides in food and water samples. Parathion, identified as an acetylcholinesterase inhibitor, had been one of the most widely used pesticides throughout the world. Symptoms of its poisoning are found to be diverse enough to include nausea, vomiting, diarrhea, muscle cramping/twitching, and shortness of breath. In this work, a graphene based impedimetric immunosensor has been fabricated and employed for highly sensitive and specific detection of parathion. The fabrication proceeded through the modification of the screen-printed carbon electrodes (SPE) with graphene sheets, followed by their functionalization with 2-aminobenzyl amine (2-ABA) via an electrochemical reaction. These amine functionalized graphene electrodes were then bio-interfaced with the anti-parathion antibodies. In the impedimetric mode, this biosensor detected parathion in a broad linear range, i.e. 0.1-1000ng/L with a very low limit of detection (52pg/L). It also showed high selectivity towards parathion in the presence of malathion, paraoxon, and fenitrothion. The viability of this biosensor was demonstrated by detecting parathion in real samples (e.g., tomato and carrot) and through cross-calibration against HPLC.
Asunto(s)
Técnicas Electroquímicas/instrumentación , Análisis de los Alimentos/instrumentación , Contaminación de Alimentos/análisis , Grafito/química , Paratión/análisis , Plaguicidas/análisis , Inhibidores de la Colinesterasa/análisis , Impedancia Eléctrica , Electrodos , Inmunoensayo/instrumentación , Límite de DetecciónRESUMEN
Halloysite nanotubes-titanium dioxide (HNTs-TiO2) as a biocompatible environmentally friendly solid-phase microextraction (SPME) fiber coating was prepared. HNTs-TiO2 was chemically coated on the surface of a fused-silica fiber using a sol-gel process. Parathion as an organophosphorus pesticide was selected as a model compound to investigate the extraction efficiency of the fiber. The extracted analyte was detected by negative corona discharge-ion mobility spectrometer (NCD-IMS). The effective parameters on the extraction efficiency, such as salt effect, extraction temperature and extraction time were investigated and optimized. The extraction efficiency of HNTs-TiO2 fiber was compared with bare-silica (sol-gel based coating without HNTs-TiO2), HNTs, carbon nanotubes and commercial SPME fibers (PA, PDMS, and PDMS-DVB). The HNTs-TiO2 fiber showed highest extraction efficiency among the studied fibers. The intra- and inter-day relative standard deviations were found to be 4.3 and 6.3%, respectively. The limit of detection and limit of quantification values were 0.03 and 0.1 µg L(-1), respectively. The dynamic range of the method was in the range of 0.1-25 µg L(-1). The spiking recoveries were between 85 (±9) and 97 (±6). The SPME-HNTs-TiO2 combined with NCD-IMS was successfully applied for the determination of parathion in apple, strawberry, celery and water samples.
Asunto(s)
Silicatos de Aluminio/química , Insecticidas/análisis , Nanotubos/química , Paratión/análisis , Microextracción en Fase Sólida/métodos , Titanio/química , Arcilla , Límite de Detección , Microscopía Electrónica de RastreoRESUMEN
Genetically-encoded biosensors offer a wide range of opportunities to develop advanced synthetic biology applications. Circuits with the ability of detecting and quantifying intracellular amounts of a compound of interest are central to whole-cell biosensors design for medical and environmental applications, and they also constitute essential parts for the selection and regulation of high-producer strains in metabolic engineering. However, the number of compounds that can be detected through natural mechanisms, like allosteric transcription factors, is limited; expanding the set of detectable compounds is therefore highly desirable. Here, we present the SensiPath web server, accessible at http://sensipath.micalis.fr SensiPath implements a strategy to enlarge the set of detectable compounds by screening for multi-step enzymatic transformations converting non-detectable compounds into detectable ones. The SensiPath approach is based on the encoding of reactions through signature descriptors to explore sensing-enabling metabolic pathways, which are putative biochemical transformations of the target compound leading to known effectors of transcription factors. In that way, SensiPath enlarges the design space by broadening the potential use of biosensors in synthetic biology applications.
Asunto(s)
Algoritmos , Técnicas Biosensibles , Ingeniería Metabólica , Redes y Vías Metabólicas , Programas Informáticos , Ácido Benzoico/análisis , Ácido Benzoico/metabolismo , Cocaína/análisis , Cocaína/metabolismo , Gráficos por Computador , Simulación por Computador , Diseño Asistido por Computadora , Bases de Datos Factuales , Bases de Datos Genéticas , Escherichia coli/genética , Escherichia coli/metabolismo , Internet , Modelos Químicos , Paratión/análisis , Paratión/metabolismo , Pseudomonas putida/genética , Pseudomonas putida/metabolismo , Biología Sintética/métodos , Factores de Transcripción/genética , Factores de Transcripción/metabolismoRESUMEN
Detection of chemical signals is critical for cells in nature as well as in synthetic biology, where they serve as inputs for designer circuits. Important progress has been made in the design of signal processing circuits triggering complex biological behaviors, but the range of small molecules recognized by sensors as inputs is limited. The ability to detect new molecules will increase the number of synthetic biology applications, but direct engineering of tailor-made sensors takes time. Here we describe a way to immediately expand the range of biologically detectable molecules by systematically designing metabolic pathways that transform nondetectable molecules into molecules for which sensors already exist. We leveraged computer-aided design to predict such sensing-enabling metabolic pathways, and we built several new whole-cell biosensors for molecules such as cocaine, parathion, hippuric acid, and nitroglycerin.
Asunto(s)
Técnicas Biosensibles , Diseño Asistido por Computadora , Redes y Vías Metabólicas , Biología Sintética/métodos , Cocaína/análisis , Simulación por Computador , Enzimas/metabolismo , Escherichia coli/metabolismo , Hipuratos/análisis , Ingeniería Metabólica , Nitroglicerina/análisis , Nitrofenoles/análisis , Paratión/análisis , Programas InformáticosRESUMEN
This paper reports the electroanalytical determination of pendimethalin and ethyl parathion by square-wave adsorptive stripping voltammetry using a material comprised of chitosan-stabilized silver nanoparticles to modify a glassy carbon electrode. Under optimized experimental conditions, the peak current was found to vary linearly with the concentration of pendimethalin in the range of 70 to 2000 nmol L(-1) and with concentration of ethyl parathion in the range of 40 to 8000 nmol L(-1). Detection limits of 36 and 40 nmol L(-1) were obtained for pendimethalin and ethyl parathion, respectively. The silver - nanoparticle-modified electrode was successfully employed for the analysis of pesticides in tap and mineral water (pendimethalin) and in lettuce and honey (ethyl parathion) samples. Pendimethalin recovery was between 94 and 100 %, and ethyl parathion recovery was between 97 and 101 %, indicating no significant matrix interference effects on the analytical results. The accuracy of the electroanalytical methodology using the proposed modified electrode was also compared to that of the UV-vis spectrophotometric method.