Concentrations Of Organophosphorus Pesticides Research Articles

Universal organophosphate pesticides detection by peptide based fluorescent probes

In practical applications, the rapid and efficient detection of universal organophosphorus pesticides (OPs) can assist inspectors in quickly identifying the presence of OPs in samples. However, this presents a challenge for most well-established methods, typically designed to detect only a specific type of organophosphorus molecule at a time. In this proof-of-concept study, we draw inspiration from the structural similarities among OPs to develop innovative peptide-based fluorescence probes for the first time, which could efficiently detect a broad range of OPs within a mere 3 min. Analysis of fluorescence curve fitting reveals a clear linear correlation between the fluorescent intensity of the peptide probes and the concentration of OPs. Additionally, the selectivity analysis indicates that these peptide fluorescent probes exhibit an excellent response to various OPs while maintaining sufficient selectivity for detecting other pesticide types. Accurate sample analysis has also highlighted the potential of these peptide probes as practical tools for the rapid detection of OPs in actual vegetable samples. In summary, this proof-of-concept study presents an innovative approach to designing and developing ultrafast, universally peptide-based OP probes. These custom-designed peptide probes may facilitate rapid sample screening and offer initial quantification for OPs, potentially saving valuable time and effort in practical OP detection.

Platinum-nickel nanoparticle-based oxidase-like nanozyme for colorimetric/photothermal dual-mode detection of organophosphorus pesticides

In this study, based on the oxidase-like (OXD) activity of platinum-nickel nanoparticles (Pt-Ni NPs) nanozyme and further in collaboration with 3,3′,5,5′-tetramethylbenzidine (TMB), a colorimetric/photothermal dual-mode probe for organophosphorus pesticides (OPs) detection was developed. TMB undergone the catalytic oxidation of Pt-Ni NPs to change from colorless to blue oxidized substance (oxTMB) and exhibited higher temperature under near-infrared irradiation. The hydrolysis product of acid phosphatase (ACP) with L-ascorbic acid 2-phosphate trisodium competed with the OXD-like activity of Pt-Ni NPs to prevent the oxidation of TMB. As the concentration of OPs grew, inhibiting the blocking effect by deactivating ACP, the generated oxTMB caused notable color and temperature changes in the reaction system. The dual-mode probe responded linearly to chlorpyrifos, with the detection limits for colorimetric and photothermal modes of 1.2 ng/mL and 1.66 ng/mL, respectively. This work proposes a simple and reliable colorimetric/photothermal platform for OPs identification, which overcomes the problem that single-mode detection probes are susceptible to external factors, and has broad application potential in the field of food safety.

Evaluation of organophosphorus pesticide tyrosine adducts for postmortem change by human serum albumin with liquid chromatography quadrupole Orbitrap mass spectrometry.

Organophosphorus pesticides (OPPs) having a phosphate ester moiety, such as malathion (MA) and methidathion (DMTP), are widely used and have been detected in many fatal cases of accidental exposure or suicide in Japan. In forensic toxicology, the accurate determination of blood OPP concentration is mandatory to prove death by OPP poisoning. However, fatal pesticide concentration in blood at autopsy varies depending on the circumstances surrounding the dead body. In this study, we found that 16 OPPs were degraded by human serum albumin (HSA) in a temperature-dependent fashion. The mechanism underlying MA, DMTP, azinphos-methyl, etrimfos, fenthion (MPP), pirimiphos-methyl, (E)-dimethylvinphos, (Z)-dimethylvinphos, vamidothion, edifenphos (EDDP), fosthiazate, and pyraclofos degradation involves the formation of adducts with tyrosine residues in HSA. The mass spectra obtained by liquid chromatography quadrupole Orbitrap mass spectrometry revealed that phosphate ester amino acid adducts such as Y-adduct1, Y-adduct2, Y-adduct3, Y-adduct4, and Y-adduct5 were formed in HSA solution incubated with OPPs. These results indicate that the 16 OPPs are postmortem changed by HSA. The detection of phosphate ester amino acid adducts such as Y-adduct1, Y-adduct2, Y-adduct3, Y-adduct4, and Y-adduct5, instead of MA, DMTP, azinphos-methyl, etrimfos, MPP, pirimiphos-methyl, (E)-dimethylvinphos, (Z)-dimethylvinphos, vamidothion, EDDP, fosthiazate, and pyraclofos per se, may be used to determine death by these OPPs poisoning.

Smartphone-assisted colorimetric biosensor for the determination of organophosphorus pesticides on the peel of fruits

Nowadays, the widespread use of organophosphorus pesticides (OPs) in agricultural production leads to varying degrees of residues in crops, which pose a potential threat to human health. Conventional methods used in national standard for the detection of OPs in fruits and vegetables require expensive instruments or cumbersome sample pretreatment steps for the analysis. To address these challenges, in this work, we took advantage of the peroxidase-like activity of PtCu3 alloy nanocrystals (NCs) for a colorimetric and smartphone assisted sensitive detection of OPs. With the assist of a smartphone, the concentration of OPs on the peel of fruits could be obtained by comparing the B/RG value (the brightness value of blue divided by those of red and green) of a test strip with a calibration curve. This work not only provides a facile and cost-effective method to detect pesticides but also makes a positive contribution to food safety warning.

Organophosphorus pesticide contaminants in fruits and vegetables: A meta-analysis

The worldwide demand for organophosphorus pesticides (OPs) in food production has raised concerns about pesticide residues. Meta-analysis, proven effective in assessing contaminants like aflatoxins and organotin compounds, is applied here to comprehensively study OP contamination in fresh fruits and vegetables. Employing Comprehensive Meta-Analysis V3.0 software, we meticulously examined 24 relevant articles encompassing 69,467 data points. Our findings revealed that while the residual concentrations of OPs (such as chlorpyrifos and profenofos) in most fruits and vegetables have typically met international or national safety standards, including Codex Alimentarius Commission, European Union, British, and Chinese standards, there are some instances in which the maximum residue limits have been exceeded, posing safety risks. Therefore, significant efforts are required to maintain residual OP contamination at safe concentrations.

Development of a fluorescent sensor based on TPE-Fc and GSH-AuNCs for the detection of organophosphorus pesticide residues in vegetables

A novel dual-signal fluorescent sensor was developed for detecting organophosphorus pesticides (OPs). It relies on the catalytic activities of acetylcholinesterase (AChE) and choline oxidase (ChOx) to generate hydrogen peroxide (H2O2) through the conversion of acetylcholine (ACh) to choline·H2O2 then oxidizes ferrocene-modified tetraphenylethylene (TPE-Fc) to its oxidized state (TPE-Fc+), resulting in enhanced cyan fluorescence due to aggregation. Simultaneously, ferrocene oxidation generates hydroxyl radicals (•OH), causing a decrease in orange fluorescence of glutathione-synthesized gold nanoclusters (GSH-AuNCs). The presence of OPs restricts AChE activity, reducing H2O2 production. Increasing OPs concentration leads to decreased cyan fluorescence and increased orange fluorescence, enabling visual OPs detection. The sensor has a linear dynamic range of 10–2000 ng/mL with a detection limit of 2.05 ng/mL. Smartphone-based color identification and a WeChat mini program were utilized for rapid OPs analysis with successful outcomes.

Detoxication of organophosphate pesticides in source waters by incorporation of an alkaline hydrolysis procedure in conventional drinking water treatment processes

Organophosphorus pesticides (OPPs) in source waters are a potential threat to drinking water safety. Although these chemicals could be removed upon chlorination in conventional water treatment, the formation of toxic decomposition products, i.e., oxons, can increase the toxicity of finished water. To address this problem, this study proposed a simple and practical treatment method for detoxifying OPPs by incorporating an alkaline hydrolysis procedure after pre-chlorination in the conventional treatment process. The experimental results showed that pre-chlorination with a chlorine dose of 1.5 mg/L could transform 87 %–92 % of OPPs with initial concentrations <50 μg/L into oxons, resulting in a significant increase in toxicity. However, by adjusting solution pH to around 11 through addition of a base fostered hydrolysis reactions of the chlorinated by-products, reducing the toxicity of the treated solution to about 0 % after a 30-minute reaction. Furthermore, the present study demonstrated that, even at a higher OPPs concentration (e.g., 100 μg/L for individual OPPs), a complete detoxification of the treated water could be achieved via adjusting pre-chlorination dose or reaction time, or hydrolysis reaction time. The presence of the common inorganic ions and organic matter in the source water matrix has negligible effects on the degradation and detoxication of OPPs. This study thus demonstrated that a combined pre-chlorination and alkaline hydrolysis process could be an effective and efficient treatment protocol for both degradation and detoxication of OPPs in water treatment.

Comparative evaluation of solid-phase extraction and in-tube liquid-liquid extraction for the determination of Organophosphorus pesticides in the surface water from Medjerda River, Tunisia

In the present work, we develop, validate, and compare two extraction procedures (in-tube liquid-liquid extraction (ITLLE) and solid-phase extraction (SPE)). The parameters that influence extraction efficiency, the nature and volume of the extraction solvent, as well as the pH nature, were improved and a standard solution of Organophosphorus pesticides (OPPs) was used. Results indicated that SPE is clearly more successful than ITLLE extraction under optimum conditions. The validated method showed that this approach had good linearity, with correlation coefficients ranging from 0.991 to 0.998 and low detection and quantification limits of 0.01–0.03 ng L−1 and 0.03–0.9 ng L−1, respectively. Relative standard deviations were in the range of 0.2 and 1.2%, while extraction recoveries varied from 79 to 97%. The SPE was selected and, optimum recoveries for OPPs were obtained at pH 7, with 10 mL of ethyl acetate. The suggested approach was effectively applied to the analysis of water samples collected from the Medjerda River in two seasons. The average OPPs concentrations ranged from not detected (ND) to 17.5 ng L−1 during the dry season and from not detected ND to 13.1 ng L−1 during the wet season. The results demonstrate that none of the OPPs concentrations measured exceeded the regulatory limits.

Distributions of OCPs and CUPs in the Sediment and Surface Water Close to a Drinking Water Reservoir in Northeastern China

In the Chinese city of Wuchang, Heilongjiang Province, a survey was conducted to track the concentrations and distributions of several organic pollutants near drinking water reservoirs, such as conventional organochlorine pesticides (OCPs) and currently in use pesticides (CUPs), including organophosphorus pesticides (OPPs) and neutral herbicides (NHs). From October 2007 to July 2008, a total of 32 pairs of water and sediment samples were gathered and examined. The results showed that the total concentrations of OCPs, OPPs, and NHs in the sediments were 0.42–7.8 ng/dm3 below the detection limit of these pollutants in sediments. The total concentration of OPPs in the water varied from the LoD to 180 ng/dm3 while NHs were 6.3 to 740 ng/dm3. While the CUP concentrations changed significantly throughout the year, the OCP concentrations were less impacted by seasonal fluctuations, indicating no recent introduction of these chemicals. The use of pesticides on crops in the primarily agricultural area was the main factor contributing to higher concentrations of CUPs during the summer.

Co-exposure of organophosphorus pesticides is associated with increased risk of type 2 diabetes mellitus in a Chinese population

ObjectiveThe epidemiological evidence of human exposure to organophosphorus pesticides (OPPs) with type 2 diabetes mellitus (T2DM) and prediabetes (PDM) is scarce. We aimed to examine the association of T2DM/PDM risk with single OPP exposure and multi-OPP co-exposure. MethodsPlasma levels of ten OPPs were measured using the gas chromatography-triple quadrupole mass spectrometry (GC-MS/MS) among 2734 subjects from the Henan Rural Cohort Study. We used generalized linear regression to estimate odds ratios (ORs) or β with 95% confidence intervals (CIs), and constructed quantile g-computation and Bayesian kernel machine regression (BKMR) models to investigate the association of OPPs mixture with the risk of T2DM and PDM. ResultsHigh detection rates ranged from 76.35% (isazophos) to 99.17% (malathion and methidathion) for all OPPs. Several plasma OPPs concentrations were in positive correlation with T2DM and PDM. Additionally, positive associations of several OPPs with fasting plasma glucose (FPG) values and glycosylated hemoglobin (HbA1c) levels were observed. In the quantile g-computation, we identified significantly positive associations between OPPs mixtures and T2DM as well as PDM, and fenthion had the greatest contribution for T2DM, followed by fenitrothion and cadusafos. As for PDM, the increased risk was largely explained by cadusafos, fenthion, and malathion. Furthermore, BKMR models suggested that co-exposure to OPPs was linked to an increased risk of T2DM and PDM. ConclusionOur findings suggested that the individual and mixture of OPPs exposure were associated with an increased risk of T2DM and PDM, implying that OPPs might act an important role in the development of T2DM.

Construction of a ratiometric fluorescent sensing platform based on near-infrared carbon dots for organophosphorus pesticides detection.

In this work, a convenient ratiometric fluorescent platform was designed to measure organophosphorus pesticides (OPs) based on acetylcholinesterase (AChE), acetylthiocholine (ATCh), manganese dioxide nanosheets (MnO2), near-infrared carbon dots (RCDs) and o-phenylenediamine (OPD). In this platform, a direct oxidation of OPD by MnO2 generated the luminescent product 2,3-diaminophenolazine (DAP) through intrinsic oxidase activity, while RCDs served as a fluorescent reference indicator. In the presence of AChE and ATCh, the enzymatic hydrolysate thiocholine (TCh) would reduce MnO2 nanosheets to Mn2+, leading to the quenching of DAP fluorescence. On the other hand, OPs can inhibit the catabolism of ATCh by AChE thus acting as a recognizer of OPs. According to these reactions, OPs were quantitatively analyzed by the intensity ratio of fluorescence emitted from RCDs and DAP (F560/F676). The constructed platform can detect OPs with the range of 0.2-0.6μM with a detection limit of 4.3nM. Figure A ratiometric fluorescent probe based on carbon dots was obtained and using it to determine the concentration of organophosphorus pesticides.

Ultrathin C3N4 nanosheets-based oxidase-like 2D fluorescence nanozyme for dual-mode detection of organophosphorus pesticides

Engineering efficient dual-mode portable sensor with built-in cross reference correction is of great significance for onsite reliable and precise detection of organophosphorus pesticides (OPs) and evading the false-positive outputs, especially in emergency case. Currently, most nanozyme-based sensors for OPs monitoring primarily replied on the peroxidase-like activity, which involved unstable and toxic H2O2. In this scenario, a hybrid oxidase-like 2D fluorescence nanozyme (PtPdNPs@g-C3N4) was yielded by in situ growing PtPdNPs in the ultrathin two-dimensional (2D) graphitic carbon nitride (g-C3N4) nanosheet. When acetylcholinesterase (AChE) hydrolyzed acetylthiocholine (ATCh) to thiocholine (TCh), it ablated O2−• from the dissolved O2 catalyzed by PtPdNPs@g-C3N4’s oxidase-like activity, hampering the oxidation of o-phenylenediamine (OPD) into 2,3-diaminophenothiazine (DAP). Consequently, with the increasing concentration of OPs which inhibited the blocking effect by inactivating AChE, the produced DAP caused an apparent color change and a dual-color ratiometric fluorescence change in the response system. Through integrating into a smartphone, a H2O2-free 2D nanozyme-based onsite colorimetric and fluorescence dual-mode visual imaging sensor for OPs was proposed with acceptable results in real samples, which holds vast promise for further development of commercial point-of-care testing platform in early warning and controlling of OPs pollution for safeguarding environmental health and food safety.

Two birds with one stone: An enzyme-regulated ratiometric fluorescent and photothermal dual-mode probe for organophosphorus pesticide detection

In this study, based on the oxidase activity and photothermal effect of manganese dioxide nanosheets (MnO2 NSs), with thiamine (TH) as the fluorescence response signal and tris (2,2'-bipyridyl) ruthenium (II) hexahydrate as the reference signal, an enzyme-regulated ratiometric fluorescence and photothermal dual-mode probe was constructed for the quantitative detection of organophosphorus pesticide (OPs) residues. OPs reduced the production of the reductive product thiocholine by inhibiting the activity of acetylcholinesterase, thereby regulating the residual amount of MnO2 NSs. With the increase of OPs concentration, the color of the probe solution gradually transitioned from red to blue, and the temperature gradually increased. Using dichlorvos and chlorpyrifos as pesticide models, the developed probes exhibited sensitive responses to OPs in a wide linear range of 0.1–8000 ng/mL. The detection limits of dichlorvos and chlorpyrifos in fluorescence mode were 1.13 × 10−3 ng/mL and 0.86 ng/mL, respectively. The corresponding detection limits in photothermal mode were 1.01 ng/mL and 1.02 ng/mL, respectively. The proposed probe displayed excellent anti-interference and reliability in the analysis of OPs residues in real samples. The dual-mode probe with self-verification function is expected to provide more accurate and robust detection results than the single-mode probe, and has a wider application prospect.

The integrated exposure assessment and potential risks of five organophosphorus pesticides in vegetables in Zhejiang, China (2018-2020).

This research surveyed the concentrations of five organophosphorus pesticides (OPs) in vegetables with the purpose of assessing the potential integrated health risks of residents. From 2018 to 2020, 870 samples of eight kinds of vegetables from Zhejiang Province were collected. Gas chromatography coupled with a flame photometric detector (GC-FPD) analyzed the five OPs. OPs were most frequently detected in celery (18.9% of samples), cowpeas (18.3% of samples), and leeks (16.9% of samples) compared to other vegetables. Among the 11 cities in Zhejiang, the cities with high detection rates of OPs were Ningbo and Hangzhou. The integrated concentrations of OPs in different cities ranged from 71.9 to 376μg/kg. The cumulative risk assessment revealed that the estimated daily intake (EDI) of leek in Wenzhou was the highest, which was 0.0077 (mg/kg bw) and 0.0059 (mg/kg bw) in adults and children respectively. The health risks of residents who consume these vegetables were within a safe range. The data provided demonstrate the distribution and potential health hazards of OPs in commonly consumed vegetables.

Spatial distribution, ecological and health risk assessment of organophosphorus pesticides identified in the water of Naseri artificial wetland, Iran

Agricultural development is inevitable to meet the growing need for food. But along with this development, there are unintended and undesirable consequences for human life and the environment that need, found a solution and corrected. One of the most important adverse consequences of agricultural development is the pollution of surface and groundwater resources, which results from various factors such as soil erosion and improper use of different pesticides. This study aimed to conduct an environmental monitoring program in Naseri wetland to determine the concentrations of organophosphorus pesticides (OPPs) in water samples and also to evaluate the potential risks (ecological and health risk assessment) of these pesticides. The salting-out assisted liquid-liquid extraction method was used to extract pesticides. The residual concentrations of OPPs evaluated by gas chromatography/mass spectrometry (GC/MS). In this study, the ecological risk of OPPs calculated for wetland ecosystem, based on the acute risk quotient (RQi) formula with maximum (RQmax), mean (RQmean), and mixture (RQmix) concentrations of organophosphorus pesticides in the wetland water. Also, to assess the health risk of consuming contaminated fish with organophosphate pesticides, the potential non-carcinogenic and carcinogenic risks were determined by the hazard quotient (Index) (HQ, HI) and incremental lifetime cancer risk (ILCR) indices, respectively. The mean ± SD concentration of OPPs (Chlorpyrifos, Malathion, Ethion, Dichlorvos, Trifluralin and Diazinon) in samples of wetland water ranged from 0.14 ± 0.08 to 0.35 ± 0.12 and 0.054 ± 0.06 to 0.2 ± 0.1 (μg/L) in summer and autumn, respectively. The mean ± SD of OPPs in fish varied from 0.68 ± 0.86 to 3.94 ± 2.7 (μg/kg). Overall, the concentrations of pesticides in all water and fish samples were below the maximum residue limit (30 μg/kg) during the study period, according to the Environmental Protection Agency (EPA) and the World Health Organization (WHO). The results of acute risk quotient were in summer (RQmax = 3.49E-4 to 0.067, RQmean = 5.8E-5 to 0.029, RQmix = 0.139-0.026, 0.018-3.42E-3) and autumn (RQmax = 8E-4 to 0.051, RQmean = 7.74E-6 to 0.018 RQmix = 0.1–0.013, 6E-3- 1.5E-3). The non-carcinogenic and carcinogenic risk indexes due to fish consumption for adults and children were (HQ = 0.026-4.68E-4, HI = 0.041, ILCR = 1.7E-7) and (HQ = 1.85E-3-1.3E-5, HI = 0.041, ILCR = 5.55E-8), respectively. The risk of OPPs was generally low. But cumulative risk (pesticide mixtures), should not be ignored.

Application of Hi-throat/Hi-volume SPE technique in assessing organophosphorus pesticides and their degradation products in surface water from Tai Lake, east China

Organophosphorus pesticides (OPPs) are among the most commonly used pesticides worldwide. However, these compounds pose a serious threat to aquatic environments. Here, thirty-seven pesticides and eight degradation products were determined in surface water samples from Tai Lake, East China, using a high-volume solid phase extraction technique (Hi-throat/Hi-volume SPE). Surface water was pumped in-situ through a portable sampler, and OPPs in the water retained on the Hi-volume SPE adsorption column, finally extracted for analysis. This technique efficiently reduced the detection limits to below 0.3 ng/L. In total, 40 out of 45 OPP congeners were detected, which far exceeded the amount of OPPs in previous studies. The total concentration of OPPs ranged between 101.4 and 1530 ng/L (median: 378.9 ng/L). Parathion exhibited the highest concentration (median: 112.0 ng/L), followed by paraoxon-methyl (median: 90.3 ng/L), as well as carbophenothion, fenthion, and mevinphos. Agricultural areas were more polluted than residential and industrial regions. However, degradation products persisted in residential and industrial waters. The ecological risks of OPPs in these areas were estimated based on the risk quotient index (RQ). Parathion, fenthion, carbophenothion, and tolclofos-methyl occurred at high-risk levels, and the levels of degradation products were also non-trivial. Our findings thus indicated that OPP degradation products pose a potential threat to natural environments and should therefore be closely monitored.

Spatiotemporal distribution and risk assessment of organophosphorus pesticides in surface water and groundwater on the North China Plain, China

90 groundwater samples and 14 surface water samples were collected in wet season (summer) and dry season (winter) in the North China Plain (NCP), and analyzed for 11 organophosphorus pesticides (OPPs). The results showed that the main types of OPPs in surface water and groundwater were dimethoate, dichlorvos, methyl-parathion, malathion in both summer and winter. The OPP concentrations in groundwater and surface water were higher in summer than in winter. In the vertical direction, the distribution characteristics of different four types of groundwater sampling points are different. In the horizontal direction: farmland adjacent to a river (FAR) > central farmland (CF) > nonfarm area adjacent to a river (NFAR) > central nonfarm area (CNF). The OPPs concentrations in surface water adjacent to farmland were higher than that in surface water adjacent to nonfarm area. The main factors influencing the distribution of OPPs in the groundwater and surface water were the interaction process between them, the groundwater flow field and the OPPs used in agricultural activities. The ecological risk of OPPs to surface water was greater in summer than in winter. Water Flea was at medium risk, and malathion had the greatest influence on Water Flea in both summer and winter. The non-carcinogenic and carcinogenic risks of the four main OPPs in surface water were higher than in groundwater, and were higher in summer than in winter, but they would not lead to adverse health effects on local residents.

A fluorescence and localized surface plasmon resonance dual-readout sensing strategy for detection of acetamiprid and organophosphorus pesticides

In this work, a fluorescence/localized surface plasmon resonance (Fluorescence/LSPR) dual-readout sensing system that using DNA functionalized gold nanoparticles (AuNPs) as nanoprobe was designed for acetamiprid (ACE) and organophosphorus pesticides (OPs) detection. The ACE detection was based on the fluorescence resonance energy transfer (FRET) between fluorochrome Cy3-labeled aptamer and AuNPs of nanoprobe. The high specificity of ACE allowed Cy3-labeled aptamer to release from nanoprobe, resulting in a significantly fluorescence recovery related to the concentration of ACE. On the other hand, the strategy for OPs detection relied on the acetylcholinesterase (AChE)-mediated oxidative polymerization blocking of dopamine on AuNPs surface and the inhibition of OPs toward AChE. The degree of polymerization of dopamine depended on the concentration of OPs, which led to a tremendous LSPR spectral shift and scattering color change of nanoprobe. The dual-readout sensing system showed great sensitivity and selectivity for ACE and OPs (used chlorpyrifos as model) with a detection limit of 166.7 pg mL−1 and 0.17fgmL−1, respectively. Moreover, two distinct color changes could be visual recognized to indicate the content of ACE and OPs, which was considered to be a conceivable way for pesticides residues assay. Therefore, this work paved a new avenue for rapid detection of multi-pesticides via a Fluorescence/LSPR dual signal response and visual screening, and hold great potential for noxious substance monitoring.

A novel electrochemiluminescence aptasensor based on copper-gold bimetallic nanoparticles and its applications

In this work, a novel electrochemiluminescence (ECL) aptasensor was structured for the detection of four organophosphorus pesticides (OPs). Firstly, multi-walled carbon nanotubes (MWCNTs) were used to create a favorable loading interface for the fixation of tris (2, 2′-bipyridyl) ruthenium (II) (Ru (bpy)32+). At the same time, copper (core)-gold (shell) bimetallic nanoparticles (Cu@Au NPs) were synthesized in the aqueous phase for the sensor construction. Gold nanoparticles (Au NPs) could promote the electrochemiluminescence intensity of Ru (bpy)32+ with high efficiency by catalyzing the oxidation process of tri-n-propylamine (TPrA). Compared with the Au NPs, Cu@Au NPs increased the solid loading of Au NPs by virtue of the large specific surface area of copper nanoparticles (Cu NPs), which could further improve the sensitivity of aptasensor. When OPs were added, the ECL intensity was significantly reduced, and the concentration of OPs could be detected through the ECL intensity. Under the optimum conditions, the aptasensor had a wider dynamic range and ultra-low detection limit for the detection of four pesticides: profenofos, isocarbophos, phorate, and omethoate, and their detection limits were 3 × 10−4 ng/mL, 3 × 10−4 ng/mL, 3 × 10−3 ng/mL, and 3 × 10−2 ng/mL respectively (S/N = 3). The aptasensor had the merits of good stability, reproducibility, and specificity, and had a favorable recovery rate in detecting OPs residues in vegetables. This work provided an effective method for the construction of a simple, rapid, and sensitive biosensor.

A BCNO QDs-MnO2 nanosheets based fluorescence “off-on-off” and colorimetric sensor with smartphone detector for the detection of organophosphorus pesticides

In this work, boron carbon oxynitride quantum dots (BCNO QDs) were prepared by a one-step hydrothermal process of ethanolamine and boric acid. BCNO QDs exhibited blue fluorescence with the optimal excitation/emission fluorescence peak at 335 and 420 nm, respectively. As an efficient fluorescence quencher, manganese dioxide (MnO2) nanosheets can effectively quench the fluorescence of BCNO QDs via the inner filter effect (IFE). Acetylcholinesterase (AChE) catalyzes the hydrolysis of acetylcholine (ATCh) to produce thiocholine (TCh). TCh can reductively degrade MnO2 nanosheets to generate Mn2+, thereby recovering the fluorescence of BCNO QDs. Organophosphorus pesticides (OPs) can inhibit the activity of AChE enzymes, thereby preventing the production of TCh and the decomposition of MnO2 nanosheets, resulting in the fluorescence “turn-off”. Therefore, the concentration of OPs can be detected by measuring the fluorescence intensity change of AChE-ATCh-MnO2-BCNO-QDs system. Under optimal experimental conditions, the dynamic detection range of paraoxon is 0.1–250 ng mL−1, and the detection limit is 0.03 ng mL−1. Meanwhile, the reaction system also showed concentration-dependent visual color changes from colorless to brownish. Furthermore, we prepared a portable BCNO QDs test paper. By using a smartphone to identify the RGB values of the reaction solution and the corresponding test paper, we carried out the digital image chromaticity analysis, which can shorten the detection time and reduce the detection cost, and provide an effective solution for the rapid detection of OPs on site.