Presence Of Organophosphorus Pesticides Research Articles

A MOF nanozyme-mediated acetylcholinesterase-free colorimetric strategy for direct detection of organophosphorus pesticides.

Although some simple and rapid colorimetric methods have been developed to detect organophosphorus pesticides (OPs), the difficult extraction and easy denaturation of acetylcholinesterase (AChE) are still drawbacks needing to be overcome. Here, we propose a MOF nanozyme-mediated AChE-free colorimetric strategy for the direct detection of OPs. In the presence of OPs (pirimiphos-methyl as a model), the intense blue of oxidized 3,3',5,5'-tetramethylbenzidine (TMB) becomes light due to the quenching effect of OPs towards hydroxyl radicals (˙OH) that are generated by the decomposition of H2O2 catalyzed by the Cu4Co6 ZIF nanozyme with excellent peroxidase (POD)-like activity. The developed colorimetric sensor exhibits assay performance and offers a universal and promising analysis strategy for detecting OPs in practical samples.

Enzyme-mediated Ru@UiO-66@MnO2 NSs/thiamine-based ratiometric fluorescence sensor for visual detection of organophosphorus pesticide residues.

In view of the potential hazards of organophosphorus pesticides (OPs), this paper constructed a ratiometric fluorescent probe utilizing a functionalized metal-organic framework to detect OPs. Ru(bpy)3Cl2 was encapsulated inside UiO-66 as a reference signal, and MnO2 nanosheets (MnO2 NSs) were grown on the surface to obtain Ru@UiO-66@MnO2 NSs. Acetylcholinesterase catalyzed the decomposition of acetylcholine into reductive thiocholine, which consumed MnO2 NSs, thus restoring the Ru@UiO-66 fluorescence. Due to the enzymatic inhibition of OPs and the redox reaction between MnO2 NSs and thiamine, this probe emitted blue fluorescence in the presence of OPs. The probe achieved linear responses to dichlorvos and chlorpyrifos with LODs of 9.99×10-6 μg mL-1 and 9.99×10-5 μg mL-1. The probe exhibited a satisfactory recovery rate for OPs in green tea. Furthermore, a hydrogel detection platform was developed by embedding the probe into sodium alginate. Overall, this work provides a visual approach to detect OPs in agricultural products.

A colorimetric sensing platform with smartphone for organophosphorus pesticides detection based on PANI-MnO2 nanozyme

Organophosphorus pesticides (OPs) are of great concern due to its potential harms on human health and the environment. Herein, a budget-friendly, rapid and convenient colorimetric sensing platform is developed for detection of OPs in the environmental and food samples. The sensing element, PANI-MnO2 nanozyme with excellent oxidase mimetic activity is synthesized at room temperature, which is able to directly oxidize 3,3,5,5-tetramethylbenzidine (TMB) to generate blue colored oxidized TMB (OxTMB) within 2 min. Ascorbic acid (AA) can inhibit the oxidization reaction of TMB, consequently causing the blue color fading. Ascorbic acid 2-phosphate (AAP) could be hydrolyzed to produce AA by alkaline phosphatase (ALP). In the presence of OPs can effectively decrease ALP activity, resulting in the recovery of catalytic activity of PANI-MnO2. Therefore, sensitive and selective OPs detection is achieved. Under the optimal conditions, excellent detection performance in term of glyphosate as a model is achieved with a linear range from 0.50 to 50 μM, the detection limit is 0.39 μM (S/N = 3). The utility of method is further improved by combining a portable smartphone platform with a color picking application. The colorimetric platform achieves instrument-free detection of OPs and overcomes the uneven color distribution of traditional paper-based chip, providing an alternative strategy for the qualitative discernment and semi-quantitative analysis of OPs on-site.

Complementary Homogeneous Electrochemical and Photothermal Dual-Modal Sensor for Highly Sensitive Detection of Organophosphorus Pesticides via Stimuli-Responsive COF/Methylene Blue@MnO2 Composite.

Credible and on-site detection of organophosphorus pesticides (OPs) in complex matrixes is significant for food security and environmental monitoring. Herein, a novel COF/methylene blue@MnO2 (COF/MB@MnO2) composite featured abundant signal loading, a specific recognition unit, and robust oxidase-like activity was successfully prepared through facile assembly processes. The multifunctional composite acted as a homogeneous electrochemical and photothermal dual-mode sensing platform for OPs detection through stimuli-responsive regulation. Without the presence of OPs, the surface MnO2 coating could recognize thiocholine (TCh), originating from acetylcholinesterase (AChE)-catalyzed hydrolysis of acetylthiocholine (ATCh), and exhibited a distinctly amplified diffusion current due to the release of plentiful MB; while the residual MnO2 nanosheets could only catalyze less TMB into oxidized TMB (oxTMB) with a typical near-infrared (NIR) absorption, enabling NIR-driven photothermal assay with a low temperature using a portable thermometer. Based on the inhibitory effect of OPs on AChE activity and OP-regulated generation of TCh, chlorpyrifos as a model target can be accurately detected with a low limit of detection of 0.0632 and 0.108 ng/mL by complementary electrochemical and photothermal measurements, respectively. The present dual-mode sensor was demonstrated to be excellent for application to the reliable detection of OPs in complex environmental and food samples. This work can not only provide a complementary dual-mode method for convenient and on-site detection of OPs in different scenarios but also expand the application scope of the COF-based multifunctional composite in multimodal sensors.

Probing the interaction and aggregation of lysozyme in presence of organophosphate pesticides: a comprehensive spectroscopic, calorimetric, and in-silico investigation

Organophosphorus pesticides (OPs) are widely used in agriculture and may contaminate food or water, leading to potential health risks. However, there are few reports on the effect of OPs on protein conformation and aggregation. Hence, in this paper, we have characterized the impact of two OPs, chlorpyrifos (CPF) and methyl parathion (Para), on the model protein HEWL using biophysical and computational methods. The steady-state and time-resolved spectroscopy, Circular dichroism (CD), molecular dynamics simulation, and isothermal titration calorimetry were employed to investigate the binding interactions between HEWL and OPs. The steady-state and time-resolved fluorescence spectroscopy confirm the presence of both static and dynamic quenching between OPs and proteins. Based on fluorescence, MD, and CD results, it was found that the OPs not only show strong binding but also destabilize the protein structure and alter the secondary and tertiary structure of the protein. The molecular docking results showed that OPs entered the binding pocket of the HEWL molecule and interacted through hydrophobic and hydrogen bond interactions. The thermodynamic studies indicated that the binding was spontaneous and OPs have shown an effect on the aggregation process of HEWL. Finally, the protein aggregation process was studied using fluorescence and SDS-PAGE studies in the presence of both the OPs and found to enhance the aggregation process in the presence of OPs. These results provide insights into the potential health risks associated with OPs and highlight the importance of understanding their interactions with biological macromolecules. Communicated by Ramaswamy H. Sarma

Levels of Contamination by Pesticide Residues, Polycyclic Aromatic Hydrocarbons (PAHs), and 5-Hydroxymethylfurfural (HMF) in Honeys Retailed in Europe

Honey is consumed worldwide because of its nutritional, therapeutic and medicinal properties. Generally, honey should reach the consumer in a pure form, but it is often contaminated in various ways. Thus, this study was designed to check for the presence of pesticide residues, polycyclic aromatic hydrocarbon (PAH) levels, and the content of 5-hydroxymethylfurfural (HMF) in selected European honeys (26 samples) obtained from shops. The most frequently detected organochlorine pesticide (OCPs) was 4,4’-DDD, which was found in fourteen honey samples. Slovakian rapeseed honey was most polluted due to the presence of eight OCPs. The presence of organophosphorus pesticides (OPs) was detected in all the analysed samples, and at least one OP in each tested sample exceeded the acceptable limit. PAHs were detected in most of the analysed samples. As for PAH4s, benzo[a]pyrene was found in forest honey from Slovakia and in Polish lime tree honey, whereas wild flower honey from the UK contained the highest level of PAH4. The investigated honeys from Spain and France met the requirements for HMF content, while honeys of Slovak, Italian and Polish origin in most cases exceeded the established levels (40 mg/kg).

Sensitive detection of organophosphorus pesticides based on the localized surface plasmon resonance and fluorescence dual-signal readout

In this work, a dual-signal visual biosensor was designed for organophosphorus pesticides (OPs) detection using DNA functionalized Ag/Au bimetallic nanoparticles (Ag/Au NPs) as multifunctional nanoprobe. The dual-signal detection strategy was based on the inhibition of enzyme-induced H2O2 generation by OPs in the detection solution containing acetylcholinesterase (AChE), choline oxidase (CHO), acetylcholine (ACh) and nanoprobe. H2O2 produced by enzyme-catalyzed reaction could trigger the etching of Ag and dissociation of carboxyfluorescein (FAM)-labeled aptamer from the nanoprobe, resulting in significant localized surface plasmon resonance (LPRR) and fluorescence (FL) signal responses. In the presence of OPs, AChE activity was inhibited to disrupt the enzymatic generation of H2O2, which allowed to simultaneous quantitative measure OPs through the LSPR peak shifts and FL intensity variations of the nanoprobe. The LSPR/FL dual-signal biosensor showed great selectivity and sensitivity for OPs detection. In addition, two distinct colour changes were visually observed to match the LSPR/FL spectra signal responses, which was a feasible means for visual analysis of OPs. Consequently, the work provided a dual-signal visual biosensor via the combination of multifunctional nanoprobe, and had significant potential to monitor pesticide residue with high anti-interference capability and detection accuracy.

Dilution or enrichment: the effects of flood on pollutants in urban rivers

BackgroundFlood events increase the risk of sediment erosion and hence the release of particle-bound pollutants besides other processes that can be observed during such events like transportation, lateral distribution and other. Macropollutants, such as acids, salts, nutrients, and natural organic matter, are usually diluted by flooding, while the effect of floods on micropollutants is still unclear. To fill this gap, Qingshui Stream, a tributary of the Jialing River in the city of Chongqing that suffered 75,000 m3·s−1 flood in August 2020 was selected in the current study to clarify effects of flood-induced pollution transportation. 14 surface water samples and 14 sediment samples were collected to analyze the occurrence of micropollutants (including 21 organochlorine pesticides (OCPs), 34 organophosphorus pesticides (OPPs) and 3 estrogenic compounds) before, during and after the flood. Finally, the environmental risks were evaluated by risk quotient (RQ).ResultsThe concentrations of total phosphorus (TP), total nitrogen (TN), chemical oxygen demand (COD) in the surface water decreased from upstream to downstream, and the amounts were diluted by flooding from 0.08 to 0.05 mg·L−1 for TP, from 0.06 to 0.02 mg·L−1 for TN and from 132 to 27 mg·L−1 for COD, respectively. The concentration of estrogenic compound was up to 90 ng·g−1, which was reduced to be lower than the limit of detection during flood. Alpha-endosulfan, delta-BHC, mirex, dichlorvos, phosdrin, thionazine, tetraethyl pyrophosphate, diazinon, methyl parathion, malathion, chlorpyrifos, famphur, and EPN were diluted by flooding, i.e., the concentration of delta-BHC reduced from 6.67 to 0.09 ng·g−1; whereas, pp'-DDD, heptachlor epoxide, o,o,o-triethylphosphorothioate, dimethoate, rabon and fensulfothion were enriched after the flood. The environmental risk was observed to be mainly arise from the presence of OPPs, which increased after flooding. The RQ values of OPPs and OCPs increased after the flood, and the potential environmental risk of OPPs accounted for the majority portion of the risk.ConclusionsThe concentrations of macropollutants in surface water and sediments, and 14 micropollutants in sediments were diluted, while pesticides such as pp′-DDD, heptachlor epoxide, o,o,o-triethylphosphorothioate, dimethoate, rabon and fensulfothion were enriched after the flood. These results suggested management on urban river should focus on potential risk of OPPs. The current study therefore could provide scientific evidence and regulatory reference for urban river ecosystem protection.

CRISPR-Cas12a based fluorescence assay for organophosphorus pesticides in agricultural products

Herein, we propose a sensitive fluorescent assay for organophosphorus pesticides (OPs) detection based on a novel strategy of activating the CRISPR-Cas12a system. Specifically, acetylcholinesterase (AChE) hydrolyzes acetylthiocholine into thiocholine (TCh). Subsequently, TCh induces the degradation of MnO2 nanosheets and generates sufficient Mn2+ ions to activate the Mn2+-dependent DNAzyme. Then, as the catalytic product of activated DNAzyme, the short DNA strand activates the CRISPR-Cas12a system to cleave the fluorophore-quencher-labeled DNA reporter (FQ) probe effectively; thus, increasing the fluorescence intensity (FI) in the solution. However, in the presence of OPs, the activity of AChE is suppressed, resulting in a decrease in FI. Under optimized conditions, the limits of detection for paraoxon, dichlorvos, and demeton were 270, 406, and 218 pg/mL, respectively. Benefiting from the outstanding MnO2 nanosheets properties and three rounds of enzymatic signal amplification, the proposed fluorescence assay holds great potential for the detection of OPs in agricultural products.

Screening of lactic acid bacteria for degrading organophosphorus pesticides and their potential protective effects against pesticide toxicity

Organophosphorus pesticides (OPPs) are a group of common residual pollutants in food that cause serious harm to human health. In the present study, the ability of 10 lactic acid bacteria (LAB) to degrade OPPs (dimethoate, parathion methyl, trichlorfon and chlorpyrifos) was explored for their potential application to degrade OPPs in fermented food. The results showed that some LAB can survive in the presence of OPPs and degrade them significantly in a short time. Among these, Lactiplantibacillus plantarum subsp. plantarum CICC20261 (L. plantarum 20261) showed the highest degradation ability. The degradation behavior of OPPs by L. plantarum 20261 followed pseudo-zero-order kinetic model (k = 1.0939–1.5915). Phosphatase produced by the strain played the key role in the degradation of OPPs because its activity was positively related to the degradation of OPPs (r = 0.975–0.995). Phosphatase could degrade OPPs rapidly in vitro, further confirmed that L. plantarum 20261 degraded rather than adsorped the OPPs. In addition, the excellent antioxidant ability of LAB and the tolerance of simulated gastric and intestinal juices showed their potential protective effects against oxidative damage induced by pesticides in vivo.

A dual-signal sensor for the analysis of parathion-methyl using silver nanoparticles modified with graphitic carbon nitride

A highly sensitive and selective method was developed for both UV–vis spectrophotometric and fluorimetric determination of organophosphorus pesticides (OPs). This method used silver nanoparticles (AgNPs) modified with graphitic carbon nitride (g-C3N4). The AgNPs reduced the fluorescence intensity of g-C3N4. Acetylthiocholine (ATCh) could be catalytically hydrolyzed by acetylcholinesterase (AChE) to form thiocholine, which induces aggregation of the AgNPs. This aggregation led to the recovery of the blue fluorescence of g-C3N4, with excitation/emission peaks at 310/460 nm. This fluorescence intensity could be reduced again in the presence of OPs because of the inhibitory effect of OPs on the activity of AChE. The degree of reduction was found to be proportional to the concentration of OPs, and the limit of fluorometric detection was 0.0324 μg/L (S/N = 3). In addition, the absorption of the g-C3N4/AgNPs at 390 nm decreased because of the aggregation of the AgNPs, but was recovered in presence of OPs because of the inhibition of enzyme activity by OPs. This method was successfully applied to the analysis of parathion-methyl in real samples.

Fluorescent peptide probes for organophosphorus pesticides detection

Extensive use of organophosphorus pesticides (OPs) in crop protection has aroused worldwidely great concern about safety and the detection of OPs is of great significance to food safety and human health. In this work, peptides attached with tetraphenylethylene (TPE) molecule were synthesized to from an aggregation-induced emission fluorescent probe (TPE-Peptide) for the determination of OPs. The working mechanism was as follows: in presence of OPs, OPs would react with active site serine in the peptide sequence via covalent bond and adducts were formed between OPs and the peptides; once formed, the adducts accelerated the aggregation of peptides, thus inducing strong emission of TPE-Peptide probe. So the adducts formation and the enhanced emission of the TPE-Peptide probe were the key factors for the OPs' sensing. Herein, the adducts formed between OPs and TPE-Peptide probe, the aggregated peptide fibrils were characterized by fluorescence, mass spectrometry, transmission electron microscopy, dynamic light scattering, atomic force microscopy, circular dichroism spectra and confocal fluorescence microscopy etc. This TPE-Peptide probe displayed highly sensitive fluorescence response where OPs' concentrations ranged from 1 to 100 μM with the limit of detection 0.6 μM and also showed selectivity.

Ratiometric fluorescence sensor for organophosphorus pesticide detection based on opposite responses of two fluorescence reagents to MnO2 nanosheets

The detection of organophosphorus pesticides (OPs) has received considerable attention for their great harm to human beings. Herein, a novel ratiometric fluorescence biosensor was constructed for the determination of OPs by using Scopoletin (SC) and Amplex Red (AR) as probe pairs that have opposite responses to MnO2 nanosheets (MnO2 NS). MnO2 NS possess peroxidase-like catalytic activity, which could quench the fluorescence of SC as well as enhance the fluorescence of the non-fluorescent substance AR by oxidation. In the absence of OPs, acetylcholinesterase (AChE) hydrolyzed acetylcholine chloride (ATCh) into choline (TCh) and acetate. TCh led the decomposition of MnO2 NS to manganese ions (Mn2+), increasing signal of SC and decreasing signal of AR. In the presence of OPs, the activity of AChE was inhibited and the decomposition of MnO2 NS was hindered, therefore the fluorescence intensity of SC was weak and the fluorescence intensity of AR had an obvious increase. Moreover, under the optimal conditions, the ratio of fluorescence intensity response recorded on the AR/SC increases with increasing the concentration of DDVP. The method has wider linear range of 5.0 pg/mL ∼500 ng/mL with a detection limit of 1.6 pg/mL, which is superior to previously reported methods. This strategy has also been applied to a visual observation based on the color change of the solution under UV light.

Modification-free carbon dots as turn-on fluorescence probe for detection of organophosphorus pesticides

It is important to detect pesticides residues due to the concern over food safety. In this work, the burning ash of waste paper was used as carbon source to synthesize carbon dots (C-dots). The fluorescence of obtained C-dots could been turn off by Fe3+ which was from Fe2+ oxidized by H2O2, organophosphorus pesticides could effectively inhibit the production of H2O2 by destroying the acetylcholinesterase activity, so the fluorescence of C-dots hold turning on in the presence of organophosphorus pesticides. Based on above principle that the fluorescence intensity of C-dots was proportional to the pesticides concentration, take chlorpyrifos for example, a universal method for pesticides detection was established. The linear range was 0.01–1.0 μg/mL with detection limit of 3 ng/mL. The method was reliable and sensitive to actual samples. The imaging of chlorpyrifos on cabbages leaves indicated this method could be used for visualization detection of organophosphorus pesticides in vegetables.

Controlled etching of gold nanorods by the Au(III)-CTAB complex, and its application to semi-quantitative visual determination of organophosphorus pesticides

The authors describe a semi-quantitative colorimetric method for visual detection of organophosphorus pesticides (OPs). It is based on the aspect ratio dependent absorbance of gold nanorods (AuNRs) which is due to the localized surface plasmon resonance. The aspect ratio can be tailored by the Au(III) complex formed with cetyltrimethylammonium bromide (CTAB) which is affected by acetylcholinesterase (AChE) based hydrolysis. OPs act as inhibitors of this reaction. In the absence of OPs, the product (thiocholine) of enzymatic hydrolysis consumes almost all the Au(III) species. In this case, the amount of residual Au(III)-CTAB complexes is small, and etching of the AuNRs does not occur. In the presence of OPs, however, the activity of AChE is inhibited. Hence, only small quantities of (or no) thiocholine is produced, and Au(III) is not consumed. Au(III) is capable of etching AuNRs and to change their aspect ratio. This leads to a color change from brownish to gray, cyan, green, blue, purple, red, and colorless that can be easily observed with bare eyes. The AuNRs were incorporated into cellulose paper to obtain a paper stripe for visual detection of OPs. Under optimal conditions, both methods (AuNRs in aqueous solutions and on paper) allowed various OPs to be determined. Applied to parathion, the method had a detection limit as low as 1.2 ppb and a linear range from 0.01 to 1.84 ppm. It was applied to the analysis of cabbage washing solutions and sea water samples, and acceptable accuracy and good resolution were found. In our preconception, the method represents a valuable tool for on-site detection of OPs in agriculture products and food.

Novel Double-Potential Electrochemiluminescence Ratiometric Strategy in Enzyme-Based Inhibition Biosensing for Sensitive Detection of Organophosphorus Pesticides.

Generally, electrochemiluminescence (ECL) ratiometric assays were based on the energy transfer (ET) between an emitter and a metal nanomaterial or between two different emitters. The choice of suitable energy donor-acceptor pair and the distance dependence of ET would greatly limit the practical application of ratiometric assays. This work explored a novel double-potential ECL ratiometry without the ET for organophosphorus pesticides (OPs) analysis, in which, reduced graphene oxide-CdTe quantum dots (RGO-CdTe QDs) and carboxyl-conjugated polymer dots (PFO dots) were chosen as cathodic and anodic ECL emitters, and the reactant (dissolved O2) and the product (H2O2) in enzymatic reactions served as their coreactants, respectively. With the occurrence of the enzymatic reactions induced by the acetylcholinesterase (AChE) and choline oxidase (ChOx), the cathodic ECL signal from RGO-CdTe QDs was at "signal off" state due to the consumption of dissolved O2. Meanwhile, the anodic ECL signal from PFO dots was at "signal on" state due to the in situ generation of H2O2. In the presence of OPs, the cathodic ECL signal would increase while the anodic ECL signal would decline correspondingly due to the inhibition of OPs on the activity of AChE. Using the reactant and the product in enzymatic reactions as the coreactants of two different ECL emitters, we conveniently achieved the opposite change trend in two ECL signals for the ratiometric detection of OPs, which exhibited a greatly improved accuracy, reliability and sensitivity, thus, showing a great attraction for developing ECL ratiometric systems for the bioanalysis.

A novel fluorimetric sensing platform for highly sensitive detection of organophosphorus pesticides by using egg white-encapsulated gold nanoclusters

Assays for organophosphorus pesticides (OPs) with high sensitivity as well as on-site screening have been urgently required to protect ecosystem and prevent disease. Herein, a novel fluorimetric sensing platform was constructed for quantitative detection of OPs via tyrosinase (TYR) enzyme-controlled quenching of gold nanoclusters (AuNCs). One-step green synthetic approach was developed for the synthesis of AuNCs by using chicken egg white (CEW) as template and stabilizer. Initially, TYR can catalyze the oxidation of dopamine to dopaminechrome, which can efficiently quench the fluorescence intensity of AuNCs at 630nm based on dynamic quenching process. However, with the presence of OPs, the activity of TYR was inhibited, resulting in the fluorescence recovery of AuNCs. This proposed fluorescence platform was demonstrated to enable rapid detection for OPs (paraoxon as model) and to provide excellent sensitivity with a detection limit of 0.1ngmL−1. Significantly, the fluorescence probe was used to prepare paper-based test strips for visual detection of OPs, which validated the excellent potential for real-time and on-site application.

New High Throughput Microtiter Plates for Detection of Organophosphorous Pesticides in Environmental Samples

Quenching of lanthanides luminescence of a novel long live Tb(III)- Ethyl 1-allyl-1,2-dihydro-4-hydroxy-2-oxoquinoline-3-carboxylate (EADHOC) as a ligand to form a complex with molar ratio 1:3 in solution has been studiedin ethanol in presence of organophosphorus pesticides both Di-chlorvos (P1) and paraoxon-Ethyl (P2). The intensity ofluminescence of Tb(III) –(EADHOC) decrease as the concentration of pesticides increase. The quenching effect wasobserved with both pesticides. Direct methods of determination of pesticides under investigated have been developed byusing luminescence of Tb(III) –(EADHOC) probe in a solution. The linear range for determination of the selectedpesticides P1(Di-chlorovos) and P2(Paraoxon-Ethyl) is 7 and 1 μM. the detection limits were 1.9 and 9.8 μM for P1(Dichlorovos)and P2 (Paraoxon-Ethyl) respectively. The Thermodynamic parameters and binding constant (K) of OPswith Tb(III) – (EADHOC) were evaluated. Including the value of enthalpy (ΔH ) and entropy( ΔS ) changes for Probeinteraction with pesticides. As the natural water sample in this study don't contain the above mentioned OPs over thelimit detected by the methods, a recovery study was carried out after the addition of the adequate amount oforganophosphorus pesticides under investigation.

Highly sensitive detection of organophosphorus pesticides by acetylcholinesterase-coated thin film bulk acoustic resonator mass-loading sensor

An acetylcholinesterase-coated thin film bulk acoustic resonator has been developed for the detection of organophosphorus pesticides. The thin film bulk acoustic resonator acts as a robust mass-sensitive transducer for bio-sensing. This device works in thickness shear mode with a resonance at 1.97GHz. The detection is based on the inhibitory effects of organophosphorus compounds on the enzymatic activity of the acetylcholinesterase immobilized on one of the faces of the acoustic resonator. The enzyme reaction in the substrate solution and the inhibitory effect is observed are real time by measuring the frequency shift. The presence of organophosphorus pesticides can be detected from the diminution of the frequency shift compared with the levels found in their absence. The device exhibits linear responses, good reproducibility, simple operation, portability and a low detection limit of 5.3×10−11M for paraoxon. The detection results of organophosphorus pesticide residues in practical samples show that the proposed sensor has the feasibility and sensing accuracy comparable to gas chromatography.

Morbidity in newborns exposed to organophosphorus pesticides

Insecticides are toxins by which we destroy harmful insects. The most frequent insecticides which are used today are organophosphorus pesticides. This group of compounds make substances whose activity mechanism is based on the inhibition of acetylcholinesterase in nerve synapsis, thus producing holynergic syndrome, resulting from the accumulation of acetylcholine which developed due to the absence of decomposition under the influence of cholinesterase. In the clinical picture of acute toxication by cholinesterase inhibitors there is a clear difference between muscarinic and nicotine effects. The basic aim of the study was to establish the effects of organophosphorus pesticides present in blood and breast milk of mothers on newborns morbidity. The study group consisted of 18 newborns whose mothers had isolated organophosphorus pesticides in their blood and breast-milk on the third day after delivery, and the control group consisted of 84 newborns whose mothers did not have isolated organophosphorus pesticides in their blood and breastmilk. Morbidity is three times greater, often in combination with some disorders of the central nervous system, and the relative risk for its appearance is eight time greater in newborns exposed to organophosphorus pesticides. Disorders that appear in newborns exposed to pesticides are mutagenic, cancerogenic and neurotoxic and some agenses could disturb the immune system which is reflected in morbidity increase, primarly of the central nervous system. The presence of organophosphorus pesticides in blood and breast milk has negative effects on newborns. In addition to acetylcholinesterase inhibition, organophosphorus pesticides react by means of other mechanisms as well.