Determination of α-methylenecyclopropylglycine in Shahi and China litchi cultivars at three different maturity stages: A quantitative study using liquid chromatography tandem mass spectrometry.

This study presents the contents of α-methylenecyclopropylglycine, a potentially toxic amino acid, in the peel, pulp and seed fractions of two well-known litchi varieties, namely Shahi and China, over a span of three harvest-seasons. For analysing α-methylenecyclopropylglycine, an LC-MS/MS-based method was validated. The method-accuracies fell within 75-110 % (RSD, <15 %) at 0.1 mg/kg (LOQ) and higher levels. A comparative evaluation of the results in peel, pulp and seed at 30 days before harvest (DBH), 15-DBH, and edible-ripe stage revealed that α-methylenecyclopropylglycine content increased as the litchi seeds grew towards maturity, regardless of the cultivar. In arils, at maturity, the concentration of α-methylenecyclopropylglycine ranged from not-detected to 11.7 µg/g dry weight. The Shahi cultivar showed slightly higher α-methylenecyclopropylglycine content in comparison to China litchi. This paper presents the first known analysis of combined seasonal data on different fruit components at various growth stages for the two chosen litchi cultivars grown in India.

Hydrogen isotope labeling unravels origin of soil-bound organic contaminant residues in biodegradability testing.

Biodegradability testing in soil helps to identify safe synthetic organic chemicals but is still obscured by the formation of soil-bound 'non-extractable' residues (NERs). Present-day methodologies using radiocarbon or stable (13C, 15N) isotope labeling cannot easily differentiate soil-bound parent chemicals or transformation products (xenoNERs) from harmless soil-bound biomolecules of microbial degraders (bioNERs). Hypothesizing a minimal retention of hydrogen in biomolecules, we here apply stable hydrogen isotope - deuterium (D) - labeling to unravel the origin of NERs. Soil biodegradation tests with D- and 13C-labeled 2,4-D, glyphosate and sulfamethoxazole reveal consistently lower proportions of applied D than 13C in total NERs and in amino acids, a quantitative biomarker for bioNERs. Soil-bound D thus mostly represents xenoNERs and not bioNERs, enabling an efficient quantification of xenoNERs by just measuring the total bound D. D or tritium (T) labeling could thus improve the value of biodegradability testing results for diverse organic chemicals forming soil-bound residues.

Validation of a global method for the simultaneous analysis of polar and non-polar pesticides by online extraction and LC-MS/MS.

BACKGROUND: Multi-residue methods for pesticide analysis in food are available for many compounds, but polar pesticides are not generally included due to their specific properties, which include high polarity and low molecular weight. Single residue methods are therefore needed for sample preparation, while chromatographic separation often requires derivatization, ion paring, or dedicated methods suitable for polar compounds, mostly ion chromatography and hydrophilic interaction liquid chromatography (HILIC). These challenges affect the important pesticide glyphosate and the related compounds aminomethylphosphonic acid (AMPA) and glufosinate. There are only a few methods including these compounds in large-scale analysis, mostly complex methods based on multidimensional chromatography. RESULTS: A new method, for the global online extraction and analysis of pesticides in beer was developed and validated. The method exploited an online trapping device, with reversed-phase (RP) and anion exchange properties, that can trap small molecules from liquid samples. The ion exchange mechanism was used to retain the very polar pesticides glyphosate, AMPA, and glufosinate. The hydrophobic properties of the trapping column were also exploited to trap pesticides suitable for multi-residue investigations. The chromatographic separation was optimized by comparison of HILIC and RP C30, which could separate pesticides, including the polar ones, with modulation by the trapping column after proper selection of the mobile phase composition and basic modifier. The validation for beer provided recoveries in the range 71-112 %, with <15 % RSD, and LOD and LOQ values of 0.02-1 and 0.3-3 µg L-1, respectively. The result was competitive with previous methods on polar pesticide analysis in beer. SIGNIFICANCE: The method was validated for 15 pesticides, over the log Kow range from -4.4 to 4.5, using a methodology with single and fast chromatographic separation under conditions compatible with multi-residue analysis by RP-LC-MS/MS. In the case of beer, for which the method was validated, the sample preparation was also performed online, after simple degassing, and sample dilution.

Ratiometric fluorescence probe based on boric acid-modified carbon dots and alizarin red for sensitive and rapid detection of glyphosate.

By combining boric acid-modified carbon dots (p-CDs) and alizarin red (ARS), a double emission probe p-CDs@ARS with fluorescence at 410 nm and 600 nm is designed for the detection of glyphosate. When Cu2+ is added, it binds with ARS to cause ARS release from p-CDs@ARS, which decreases the fluorescence at 600 nm. However, in the presence of glyphosate, glyphosate competes to the binding of Cu2+, releasing ARS to bind with p-CDs again. Therefore, the fluorescence of 600 nm recovers. Based on this, the fluorescence of 410 nm and 600 nm act as the reference and response signal, respectively, achieving the ratiometric fluorescence detection of glyphosate. The linear range of glyphosate detection is 0.5-50 µM with a limit of detection at 0.37 µM which is well below the maximum residue limit for glyphosate in food. When the probe is used to detect the glyphosate residue in Pearl River water and cucumber, the detection results are well consistent with those detected by HPLC. The established method based on p-CDs@ARS has the advantages that the assembly of ratiometric fluorescence probe is simple, and the detection speed is fast. Additionally, a typical INHIBIT logical system has been successfully constructed based on glyphosate, Cu2+, and the fluorescence signal of p-CDs@ARS.

Dual colorimetric platforms for direct detection of glyphosate based on Os-Rh nanozyme with peroxidase-like activity.

BACKGROUND: To minimize the impact of pesticide residues in food on human health, it is necessary to enhance their detection. Recently, many nanozyme-based colorimetric methods for pesticides detection have been developed, however, they often required the assistance of natural enzymes, which made the process and result of methods susceptible to the stability and activity of natural enzymes. To overcome these drawbacks, methods for direct detection of pesticides using nanozymes have been developed, and there are few studies in this field currently. Thus, it is of great research and practical significance to develop more nanozymes-based colorimetric methods for direct detection of pesticides. RESULTS: Dual colorimetric platforms based on Os-Rh nanozyme with excellent peroxidase-like activity were constructed for directly detection of glyphosate in this work. Results showed that glyphosate was able to sensitively and selectively inhibit the peroxidase-like activity of Os-Rh nanozyme through hindering the decomposition of H2O2 by Os-Rh nanozyme to produce HO∙. Based on this, the dual colorimetric platforms achieved highly sensitive detection for glyphosate over a wide linear concentration range (50-1000 µg L-1 in solution platform and 200-1000 µg L-1 in paper platform), with the detection limits of 28.37 µg L-1 in solution platform and 400 µg L-1 (naked-eye detection limit)/123.25 µg L-1 (gray scale detection limit) in paper platform, respectively. Moreover, the dual colorimetric platforms possessed satisfactory reliability and accuracy for practical applications, and has been successfully applied to the detection of real samples with the spiked recoveries of 92.78-102.75 % and RSD of 1.17-3.88 %. SIGNIFICANCE: The dual colorimetric platforms for glyphosate direct detection based on Os-Rh nanozyme developed in this work not only owned considerable practical application potential, but also could provide more inspirations and ideas for the rational design and development of colorimetric sensing methods for the rapid detection of pesticides based on nanozymes.

Widespread occurrence of glyphosate and aminomethylphosphonic acid in indoor dust from urban homes across the United States and its contribution to human exposure.

Glyphosate is the most widely used herbicide worldwide, with concerns over human exposure and potential health risks. Nevertheless, little is known about the sources of human exposure to glyphosate and its degradation product, aminomethylphosphonic acid (AMPA). In this study, we measured glyphosate and AMPA in 99 indoor dust samples collected from urban homes in sixteen states in the USA. Glyphosate and AMPA were detected in all samples at geometric mean (GM) concentrations of 193 and 30.8 ng/g, respectively. We found a strong and significant positive correlation between glyphosate and AMPA concentrations (r = 0.70, p < 0.01), indicating that the latter mainly originated from glyphosate. The concentrations of glyphosate (r = 0.40, p < 0.01) and AMPA (r = 0.33, p < 0.01) in indoor dust were significantly correlated with the county-wide agricultural usage of this herbicide. Human exposure to glyphosate and AMPA through dust ingestion were in the ranges of 0.05-0.85 and 0.01-0.14 ng/kg body weight (BW)/day, respectively, for various age groups, which were more than two orders of magnitude below the acceptable daily intake for glyphosate (500 µg/kg BW/day). Further studies are needed to identify the sources and health outcomes of human exposure to glyphosate.

A lateral strip assay for ultrasensitive detection of glyphosate in soybeans and corn.

Glyphosate (GLY) is widely applied in agriculture and horticulture as a herbicide. The development of genetically modified plants has caused abuse of GLY, with excessive residues potentially causing harm to human health. Consequently, a novel method needs to be built to detect GLY in soybeans and corn. Computer simulation was used to design an excellent hapten which was used to produce an anti-GLY monoclonal antibody (mAb) with outstanding sensitivity and affinity, and its 50%-inhibitory concentration (IC50) was 128.59 ng mL-1. Afterwards, an immunochromatographic assay strip was developed based on the mAb. In soybeans and corn, the visual detection limits were 1 mg kg-1 and 0.2 mg kg-1, while the cut-off values were 50 mg kg-1 and 5 mg kg-1, respectively. The reliability of the strips was proved by the existing methods. Thus, a rapid method to detect GLY residues on-site in soybeans and corn was established.

Soil degradation and herbicide pollution by repeated cassava monoculture within Thailand's conservation region.

In a national park in Northeast Thailand, agricultural land has been converted from natural forest by small-scale farmers for cassava agriculture. We hypothesise that long-termed cassava monoculture leads to the degradation of soil properties. To test the hypothesis, we conducted a five-year (2016-2020) study on the physical and chemical properties of soil in cassava farmland, and also examined the soil properties of its adjacent natural forests, as a control. The examined cassava farmland was converted from the natural forest during the five years from 2011 to 2015. The significant decrease in organic carbon and the increases in exchangeable potassium and bulk density were found in 2016, indicating that these soil properties varied quickly following the farmland conversion. On the other hand, the significant increase in soil nitrogen and the decrease in pH were found later in 2020, indicating that these soil properties were gradually altered by repeated agricultural activities, such as fertilizer application and trampling. In contrast, there were no significant differences in available phosphate, electrical conductivity, cation exchange capacity, and the soil texture (the fractions of sand, silt, and clay) among the forest and farmland soils. The cation exchange capacity was positively correlated to the fraction of clay, the organic carbon, and pH. The use of glyphosate and paraquat herbicides is prohibited within national parks in Thailand. However, in 2020, glyphosate was detected in farmland soil (up to 5.0 mg kg-1) during both the rainy and dry seasons, and glyphosate (up to 2.5 mg l-1) was detected in stream water from the farmland during the dry season at least in 2020. Soil degradation and herbicide pollution may carry a high risk of causing irreversible changes in terrestrial ecosystems. We discuss the root causes of this issue from perspectives of agricultural production, economy, and the environmental impact, and propose effective policy measures.

Glyphosate contamination in European rivers not from herbicide application?

The most widely used herbicide glyphosate contaminates surface waters around the globe. Both agriculture and urban applications are discussed as sources for glyphosate. To better delineate these sources, we investigated long-term time series of concentrations of glyphosate and its main transformation product aminomethylphosphonic acid (AMPA) in a large meta-analysis of about 100 sites in the USA and Europe. The U.S. data reveal pulses of glyphosate and AMPA when the discharge of the river is high, likely indicating mobilization by rain after herbicide application. In contrast, European concentration patterns of glyphosate and AMPA show a typical cyclic-seasonal component in their concentration patterns, correlating with patterns of wastewater markers such as pharmaceuticals, which is consistent with the frequent detection of these compounds in wastewater treatment plants. Our large meta-analysis clearly shows that for more than a decade, municipal wastewater was a very important source of glyphosate. In addition, European river water data show rather high and constant base mass fluxes of glyphosate all over the year, not expected from herbicide application. From our meta-analysis, we define criteria for a source of glyphosate, which was hidden so far. AMPA is known to be a transformation product not only of glyphosate but also of aminopolyphosphonates used as antiscalants in many applications. As they are used in laundry detergents in Europe but not in the USA, we hypothesize that glyphosate may also be a transformation product of aminopolyphosphonates.

First investigation of the temporal distribution of neurotoxin ß-N-methylamino-L-alanine (BMAA) and the candidate causative microalgae along the South Sea Coast of Korea.

The neurotoxin ß-N-methylamino-L-alanine (BMAA), produced by cyanobacteria and diatoms, has been implicated as an environmental risk factor for neurodegenerative diseases. This study first investigated the occurrence and monthly distributions of BMAA and its isomers, 2,4-diaminobutyric acid (DAB) and N-2-aminoethylglycine (AEG), in phytoplankton and mussels from 11 sites along the South Sea Coast of Korea throughout 2021. These toxins were quantified using LC-MS/MS, revealing elevated BMAA concentrations from late autumn to spring, with phase lags observed between phytoplankton and mussels. The highest concentration of BMAA in phytoplankton was detected in November (mean: 1490 ng g-1 dry weight (dw)), while in mussels, it peaked in December (mean: 1240 ng g-1 dw). DAB was detected in phytoplankton but was absent in mussels, indicating limited bioaccumulation potential. In February, the peak mean DAB concentration in phytoplankton was 89 ng g-1 dw. AEG was not detected in any samples. Chlorophyll-a concentrations consistently showed an inverse correlation with BMAA concentrations in mussels throughout the year. Through correlation analysis, four diatom genera, Bacillaria, Hemiaulus, Odontella, and Pleurosigma, were identified as potential causative microalgae of BMAA. This study offers insights into identifying the causative microalgae for BMAA and informs future regulatory efforts regarding unmanaged biotoxins.

Nanomolar level electrochemical detection of glycine on a miniaturized modified screen-printed carbon-based electrode: a comparison of performance with glassy carbon electrode system.

In this work, we demonstrate the electrochemical (EC) sensing of glycine (GLY) on a gold-copper nanocluster on nitrogen-doped graphene quantum dot-modified (indigenously fabricated) screen-printed electrode (AuCuNC@N-GQD/SPE). SPE was fabricated by step-by-step printing of reference, working, and counter electrodes to develop an all-printed SPE. A comparison strategy between SPE and the glassy carbon electrode (GCE) towards the EC sensing of GLY was carried out. The sensing performance was enhanced while replacing GCE with SPE. The limit of detection (LOD) for GLY obtained by EC sensing with AuCuNC@N-GQD/GCE was 10 nM and that with AuCuNC@N-GQD/SPE was 10 times lower, 1 nM, and is the lowest LOD value reported hitherto. Compared with AuCuNC@N-GQD/GCE, the current response of AuCuNC@N-GQD/SPE exhibited a ∼2.6-times enhancement with a sensitivity of 0.206 µA µM-1 cm-2. Thus, the successful shift from GCE to SPE not only miniaturizes the sensor device but also enhances the electrochemical detection performance.

Dual-recognition "turn-off-on" fluorescent Biosensor triphenylamine-based continuous detection of copper ion and glyphosate applicated in environment and living system.

Heavy metal Cu2+ emitted in industry and residues of glyphosate pesticides are pervasive in ecosystems, accumulated in water bodies and organisms' overtime, constituting hazard to human and ecological balance. The development of rapid, highly selective, reversibility and sensitive biosensor in vivo detection for Cu2+ and glyphosate was imminent. A novel dual-recognition fluorescence biosensor MPH was successfully synthesized based on triphenylamine, which demonstrated remarkable ratiometric fluorescence quenching toward Cu2+, while MPH-Cu2+ (1:1) ensemble exhibited ratiometric fluorescence restoration for glyphosate, both with observable color changes in daylight and UV lamp. The biosensor exhibited rapid, outstanding selectivity, anti-interference, and multiple cycles reversibility through "turn-off-on" fluorescence towards Cu2+ and glyphosate, respectively. Surprisingly, the clearly binding mechanisms of MPH to Cu2+ and MPH-Cu2+ ensemble to glyphosate were determined, respectively, based on the Job's plot, FT-IR, ESI-HRMS, 1H NMR titration and theoretical calculations of dynamics and thermodynamics. In addition, biosensor MPH demonstrated successful detection of Cu2+ and glyphosate across diverse environmental samples including tap water, extraction solutions of traditional Chinese medicine honeysuckle and soil samples. In the meantime, fluorescence imaging of Cu2+ and glyphosate at both micro and macro scales in various living organisms, such as rice roots, MCF-7 cells, zebrafish, and mice, were successfully achieved. Overall, this work was expected to become a promising and versatile fluorescence biosensor for rapid and reversible detection of Cu2+ and glyphosate both in vitro and vivo.

Glyphosate and other plant protection products in size-segregated urban aerosol: Occurrence and dimensional trend.

Plant protection products (PPPs) play a fundamental role in the maintenance of agricultural fields and private/public green areas, however they can contaminate zones nearby the application point due to wind drift, resuspension, and evaporation. Several studied have deepened the relationship between PPPs and living beings' health, suggesting that these products might have a negative influence. Some PPPs belong to the class of Emergent Contaminants, which are compounds whose knowledge on the environmental distribution and influence is limited. These issues are even more stressed in urban aerosol, due to the high residential density that characterizes this area. Therefore, this study assessed the contamination caused by polar PPPs, such as herbicides (i.e., Glyphosate), fungicides (i.e., Fosetyl Aluminium), and growth regulators (i.e. Maleic Hydrazide), in size-segregated urban aerosol and evaluated their concentration variability with respect to atmospheric parameters (humidity, temperature, rain). Moreover, hypotheses on possible sources were formulated, exploiting also back-trajectories of air masses. A total of six PPPs were found in the samples: glyphosate was more present in the coarse fraction (2.5-10 µm), Fosetyl Aluminium, chlorate and perchlorate were more present in the coarse/fine fractions (10-1 µm), while cyanuric acid and phosphonic acid were mostly concentrated in the fine/ultrafine fractions (<1 µm). While for the first four we suspect of local sources, such as private gardening, the two latter might derive from the entire Po Valley, a highly polluted area in the North of Italy, and from degradation of other substances.

How do glyphosate and AMPA alter the microbial community structure and phosphorus cycle in rice-crayfish systems?

Glyphosate, a commonly used organophosphorus herbicide in rice-crayfish cropping regions, may alter regional phosphorus cycle processes while affecting the structure of microbial communities. However, the effects of glyphosate residues on rice-crayfish systems remain unclear. In this study, we assessed the spatial and temporal distribution characteristics of glyphosate and its primary degradation products, as well as the impact mechanisms of glyphosate on microbial communities and the phosphorus cycle in rice-crayfish systems such as paddy fields, breeding ditches and recharge rivers. The detection rates of glyphosate and aminomethylphosphonic acid (AMPA) were 100% in rice-crayfish systems. Concentrations of glyphosate in the water phase and soil/sediment were as high as 0.012 µg/L and 7.480 µg/kg, respectively, and concentrations of AMPA were as high as 17.435 µg/L and 13.200 µg/kg, respectively. Glyphosate concentrations were not affected by rainfall or sampling site, but concentrations of AMPA in the water phase of recharge rivers were affected by rainfall. The glyphosate concentration was significantly and positively correlated with RBG-16-58-14 abundance, and the AMPA concentration was significantly and positively correlated with Actinobacteria and Lysobacter abundance, and negatively correlated with Cyanobacteria abundance (P < 0.05). The highest abundances of phoD, phnK, and ppx genes were found in all soils/sediments. Glyphosate concentration in soil/sediment was significantly and positively correlated with the abundance of phoD gene encoding an organophosphorus-degrading enzyme and ppx gene encoding poly inorganic phosphate (Pi) hydrolase (P < 0.05). In addition, the glyphosate concentration was significantly and positively correlated with the Ca-bonded Pi content (P < 0.05). This implies that glyphosate may promote the production of stable Pi in rice-crayfish systems by increasing the abundance of phoD and ppx genes. The results of this study reveal the impact mechanism of glyphosate on the phosphorus cycle in rice-crayfish systems and provide a basis for the risk assessment of glyphosate.

Soil hydro-physical variables and crop residues determinate runoff, soil loss, and glyphosate and AMPA concentration in the aqueous phase under simulated rainfall events.

Soil structural degradation and water erosion processes were observed even in no-tillage schemes in the Pampas region. Within these conservation systems, agrochemical application per hectare is one of the highest globally. Thus, this entails a serious risk of water contamination. The objectives of this study were to (1) test the hypothesis that the hydrological dynamics and sediment concentration related to surface runoff were conditioned by soil structure regardless of the presence of maize (Zea mays L.) crop residue and (2) assess the incidence of maize crop residue on glyphosate and aminomethylphosphonic acid (AMPA) concentration in runoff. The soil under study corresponded to Arroyo Dulce Series (Typic Argiudoll silty loam soil). Rain simulations were performed in the laboratory on undisturbed soil samples. Total runoff and infiltration rate were similar between treatments with C(+) and without C(-) maize crop residues (C(+) 1381.40 mL and 14.27 mm h-1, C(-): 1529.70 mL and 21.67 mm h-1). The C(-) treatments showed a higher sediment concentration than C(+) (1.58 and 0.42 g 100 mL-1, respectively). Glyphosate and AMPA average values in runoff were 15.9 and 33.9 µg L-1. High variability of the hydro-physical properties and occurrence of soil structure, particularly platy ones, were detected. The hydrological variables were conditioned mainly by the occurrence of platy structures regardless of crop residue presence. Glyphosate concentration was increased in the first runoff event by the presence of corn residues, while AMPA concentrations were higher in the second runoff event in both residue treatments. In this study, maize residue on the soil surface protected the soil from sediment detachment but did not change runoff or infiltration. Thus, the implementation of agricultural management practices that promote vegetative residue cover has shown positive results to erosion.

Confined within a sugarcane monoculture: A participatory assessment of water pollution and potential health risks in the community of El Tiple, Colombia.

Communities neighboring monoculture plantations are vulnerable to different forms of pollution associated with agro-industrial operations. Herein, we examine the case of El Tiple, a rural Afro descendant community embedded within one of the largest sugarcane plantations in the Americas. We implemented a participatory approach to assess water pollution, exposure via water ingestion, and non-carcinogenic health risks associated with the use of local water sources available to the community. We conducted household surveys to unveil demographic characteristics and family dynamics linked to water consumption. Additionally, we measured water quality parameters and assessed the concentration glyphosate, its major metabolite (aminomethylphosphonic acid) and metals and metalloids. Drinking water El Tiple households is sourced from three primary sources: the local aqueduct system, water delivery trucks, and private deep wells. Tests on water samples from both the local aqueduct and delivery trucks showed no traces of pesticides, metals, or metalloids surpassing regulatory limits set by Colombian or EPA standards. However, we found concentration of contaminants of primary concern, including mercury (up to 0.0052 ppm) and lead (up to 0.0375 ppm) that exceed the permissible regulatory thresholds in water from groundwater wells. Residents of the peripheric subdivisions of El Tiple are four times more reliant on well water extraction than residents of the central area of the town due to lack of access to public drinking water and sanitation infrastructure. Finally, adult women and school-age children have a higher health risk associated with exposure to local pollutants than adult men due to their constant presence in the town. We conclude that expanding the coverage of clean water and sanitation infrastructure to include all households of the community would be the most recommended measure to minimize exposure and risk via ingestion of water pollutants.

A global assessment of glyphosate and AMPA inputs into rivers: Over half of the pollutants are from corn and soybean production.

Glyphosate is widely used in agriculture for weed control; however, it may pollute water systems with its by-product, aminomethylphosphonic acid (AMPA). Therefore, a better understanding of the flows of glyphosate and AMPA from soils into rivers is required. We developed the spatially explicit MARINA-Pesticides model to estimate the annual inputs of glyphosate and AMPA into rivers, considering 10 crops in 10,226 sub-basins globally for 2020. Our model results show that, globally, 880 tonnes of glyphosate and 4,090 tonnes of AMPA entered rivers. This implies that 82 % of the river inputs were from AMPA, with glyphosate accounting for the remainder. Over half of AMPA and glyphosate in rivers globally originated from corn and soybean production; however, there were differences among sub-basins. Asian sub-basins accounted for over half of glyphosate in rivers globally, with the contribution from corn production being dominant. South American sub-basins accounted for approximately two-thirds of AMPA in rivers globally, originating largely from soybean production. Our findings constitute a reference for implementing and supporting effective control strategies to achieve Sustainable Development Goals 2 and 6 (food production and clean water, respectively) simultaneously in the future.

Exploring the Use of a Lipopeptide in Dipalmitoylphosphatidylcholine Monolayers for Enhanced Detection of Glyphosate in Aqueous Environments.

The growing reliance on pesticides for pest management in agriculture highlights the need for new analytical methods to detect these substances in food and water. Our research introduces a SPRWG-(C18H37) lipopeptide (LP) as a functional analog of acetylcholinesterase (AChE) for glyphosate detection in environmental samples using phosphatidylcholine (PC) monolayers. This LP, containing hydrophilic amino acids linked to an 18-carbon aliphatic chain, alters lipid assembly properties, leading to a more flexible system. Changes included reduced molecular area and peak pressure in Langmuir adsorption isotherms. Small angle X-ray scattering (SAXS) and atomic force microscopy (AFM) analyses provided insights into the LP's structural organization within the membrane and its interaction with glyphosate (PNG). Structural and geometric parameters, as derived from in silico molecular dynamics simulations (MD), substantiated the impact of LP on the monolayer structure and the interaction with PNG. Notably, the presence of the LP and glyphosate increased charge transfer resistance, indicating strong adherence of the monolayer to the indium tin oxide (ITO) surface and effective pesticide interaction. A calibration curve for glyphosate concentration adjustment revealed a detection limit (LOD) of 24 nmol L-1, showcasing the high sensitivity of this electrochemical biosensor. This LOD is significantly lower than that of a similar colorimetric biosensor in aqueous media with a detection limit of approximately 0.3 µmol L-1. Such an improvement in sensitivity likely stems from adding a polar residue to the amino acid chain of the LP.

A ratiometric fluorescence and colorimetry dual-signal sensing strategy based on o-phenylenediamine and AuNCs for determination of Cu2+ and glyphosate.

A ratiometric fluorescence sensing strategy has been developed for the determination of Cu2+ and glyphosate with high sensitivity and specificity based on OPD (o-phenylenediamine) and glutathione-stabilized gold nanoclusters (GSH-AuNCs). Water-soluble 1.75-nm size GSH-AuNCs with strong red fluorescence and maximum emission wavelength at 682 nm were synthesized using GSH as the template. OPD was oxidized by Cu2+, which produced the bright yellow fluorescence oxidation product 2,3-diaminophenazine (DAP) with a maximum fluorescence emission peak at 570 nm. When glyphosate existed in the system, the chelation between glyphosate and Cu2+ hindered the formation of DAP and reduced the fluorescence intensity of the system at the wavelength of 570 nm. Meanwhile, the fluorescence intensity at the wavelength of 682 nm remained basically stable. It exhibited a good linear relationship towards Cu2+ and glyphosate in water in the range 1.0-10 µM and 0.050-3.0 µg/mL with a detection limit of 0.547 µM and 0.0028 µg/mL, respectively. The method was also used for the semi-quantitative determination of Cu2+ and glyphosate in water by fluorescence color changes visually detected by the naked eyes in the range 1.0-10 µM and 0.30-3.0 µg/mL, respectively. The sensing strategy showed higher sensitivity, more obvious color changes, and better disturbance performance, satisfying with the detection demands of Cu2+ and glyphosate in environmental water samples. The study provides a reliable detection strategy in the environment safety fields.

A dual-signals fluorometric and colorimetric peptide-based probe for Cu(II) and glyphosate detection and its application for bioimaging and water testing.

A novel dual-signal fluorometric and colorimetric probe FMDH (5-FAM-Met-Asp-His-NH2), incorporating a tripeptide (Met-Asp-His-NH2) linked to 5-carboxyfluorescein (5-FAM), was firstly synthesised. FMDH demonstrated exceptional selectivity and sensitivity, rapid response, wide pH response range and robust anti-interference capabilities for monitoring Cu2+. This was achieved through a distinctive naked-eye colorimetric and fluorescent quenching behaviour. A good linearity within the range of 0-3 µM (R2 = 0.9914) was attained, and the limit of detection (LOD) for Cu2+ was 47.4 nM. Furthermore, the FMDH-Cu2+ ensemble responded to glyphosate with notable selectivity and sensitivity. A good linear correlation (R2 = 0.9926) was observed at the lower concentration range (2.4-7.8 µM) and achieving a detection limit as low as 29.9 nM. The response time of FMDH with Cu2+ and glyphosate were less than 20 s, and the pH range of 7-11 that was suitable for practical application under physiological pH conditions. MTT assays confirmed that FMDH offers good permeability and low toxicity, facilitating successful application in imaging analysis of Cu2+ and glyphosate in living cells and zebrafish. In addition, FMDH was employed in the detection of these analytes in real water samples. Cost-effective, highly sensitive and easily prepared FMDH-impregnated test strips were developed for the efficient visual detection of Cu2+ and glyphosate under 365 nm UV light. Increasing concentrations of Cu2+ and glyphosate resulted in notable colour changes under 365 nm UV light, enabling visual semi-quantitative analysis via a smartphone colour-analysis App.