Inkjet-assisted layer-by-layer printing of quantum dot/enzyme microarrays for highly sensitive detection of organophosphorous pesticides

A novel honeycomb-like 3D-printed device for rotating-disk sorptive extraction of organochlorine and organophosphorus pesticides from environmental water samples

In this study, 3D-printing based on fused-deposition modeling (FDM) was employed as simple and cost-effective strategy to fabricate a novel format of rotating-disk sorptive devices. As proof-of-concept, twenty organochlorine and organophosphorus pesticides were determined in water samples through rotating-disk sorptive extraction (RDSE) using honeycomb-like 3D-printed disks followed by gas chromatography coupled to mass spectrometry (GC-MS). The devices that exhibited the best performance were comprised of polyamide + 15 % carbon fiber (PA + 15 % C) with the morphology being evaluated through X-ray microtomography. The optimized extraction conditions consisted of 120 min of extraction using 20 mL of sample at stirring speed of 1100 rpm. Additionally, liquid desorption using 800 µL of acetonitrile for 25 min at stirring speed of 1100 rpm provided the best response. Importantly, the methodology also exhibited high throughput since an extraction/desorption platform that permitted up to fifteen simultaneous extractions was employed. The method was validated, providing coefficients of determination higher than 0.9706 for all analytes; limits of detection (LODs) and limits of quantification (LOQs) ranged from 0.15 to 3.03 μg L-1 and from 0.5 to 10.0 μg L-1, respectively. Intraday precision ranged from 4.01 to 18.73 %, and interday precision varied from 4.83 to 20.00 %. Accuracy was examined through relative recoveries and ranged from 73.29 to 121.51 %. This method was successfully applied to analyze nine groundwater samples from monitoring wells of gas stations in São Paulo. Moreover, the greenness was assessed through AGREEprep metrics, and an overall score of 0.69 was obtained indicating that the method proposed can be considered sustainable.

A highly efficient metal oxide incorporated metal organic framework [Nd2O3-MIL(Fe)-88A] for the electrochemical detection of dichlorvos

In this study, a Nd₂O₃@MIL(Fe)-88A composite was prepared through a hydrothermal method and used to detect dichlorvos. The XRD result demonstrated that the prepared sensor is highly crystalline in nature. The affinity of metal oxide and MIL(Fe)-88A could be utilised to overcome low stability and sensitivity owing to their synergistic and electronic effects. Differential pulse voltammetry (DPV) exhibits the electrocatalytic behaviour of Nd₂O₃@MIL(Fe)-88A; it functions at a lower potential at -0.5 to 0.8 V and has a wide linear range of 1-250 nM. It shows a very low detection limit of 0.92 nM with good sensitivity (4.42 mA nM^-1) and selectivity. The developed Nd₂O₃@MIL(Fe)-88A sensor was successfully applied to detect dichlorvos in real analysis. The recovery range calculated for cabbage and orange extracts was 96-97% and 99.5-103.4%, respectively, and RSD% calculated for cabbage and orange extracts was from 1.40 to 3.39% and from 0.64 to 2.26%, respectively.

Advances in organophosphorus pesticides pollution: Current status and challenges in ecotoxicological, sustainable agriculture, and degradation strategies

Organophosphorus pesticides (OPPs) are one of the most widely used types of pesticide that play an important role in the production process due to their effects on preventing pathogen infection and increasing yield. However, in the early development and application of OPPs, their toxicological effects and the issue of environmental pollution were not considered. With the long-term overuse of OPPs, their hazards to the ecological environment (including soil and water) and animal health have attracted increasing attention. Therefore, this review first clarified the classification, characteristics, applications of various OPPs, and the government's restriction requirements on various OPPs. Second, the toxicological effects and metabolic mechanisms of OPPs and their metabolites were introduced in organisms. Finally, the existing methods of degrading OPPs were summarized, and the challenges and further addressing strategy of OPPs in the sustainable development of agriculture, the environment, and ecology were prospected. However, methods to solve the environmental and ecological problems caused by OPPs from the three aspects of use source, use process, and degradation methods were proposed, which provided a theoretical basis for addressing the stability of the ecological environment and improving the structure of the pesticide industry in the future.

Recent Advances on Detection of Insecticides Using Optical Sensors

Insecticides are enormously important to industry requirements and market demands in agriculture. Despite their usefulness, these insecticides can pose a dangerous risk to the safety of food, environment and all living things through various mechanisms of action. Concern about the environmental impact of repeated use of insecticides has prompted many researchers to develop rapid, economical, uncomplicated and user-friendly analytical method for the detection of insecticides. In this regards, optical sensors are considered as favorable methods for insecticides analysis because of their special features including rapid detection time, low cost, easy to use and high selectivity and sensitivity. In this review, current progresses of incorporation between recognition elements and optical sensors for insecticide detection are discussed and evaluated well, by categorizing it based on insecticide chemical classes, including the range of detection and limit of detection. Additionally, this review aims to provide powerful insights to researchers for the future development of optical sensors in the detection of insecticides.

An Overview on the Mechanisms and Applications of Enzyme Inhibition-Based Methods for Determination of Organophosphate and Carbamate Pesticides

Acetylcholinesterase inactivating compounds, such as organophosphate (OP) and carbamate (CM) pesticides, are widely used in agriculture to ensure sustainable production of food and feed. As a consequence of their applications, they would result in neurotoxicity, even death. In this essence, the development of enzyme inhibition methods still shows great significance as rapid detection techniques for on-site large-scale screening of OPs and CMs. Initially, mechanisms and applications of various enzyme-inhibition-based methods and devices, including optical colorimetric assay, fluorometric assays, electrochemical biosensors, rapid test card, and microfluidic device, are highlighted in the present overview. Further, to enhance the enzyme sensitivity for detection; alternative enzyme sources or high yield enrichment methods (such as abzyme, artificial enzyme, and recombinant enzyme), as well as enzyme reactivation and identification, are also addressed in this comprehensive overview.

Easy-to-use and reliable absorbance-based MPH-GST biosensor for the detection of methyl parathion pesticide

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Simple, inexpensive, high-efficiency absorbance-based OP biosensor was fabricated.

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Covalently immobilized methyl parathion hydrolase was used as a biomolecule.

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The biosensor can be used at room temperature for 100 rounds repetitively.

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The biosensor could detect MP with the detection limit of 0.1 μM.

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The biosensor showed high reliability for detecting MP in real samples.

Due to high contamination of organophosphate (OP) insecticides in agricultural products and the environment, efficient and convenient devices for their monitoring are necessary. Here, a simple, inexpensive, efficient, and easy-to-use absorbance-based biosensor was fabricated utilizing recombinant methyl parathion hydrolase fused with glutathione-S-transferase (MPH-GST), covalently immobilized onto a chitosan film-coated polystyrene microplate, for the detection of methyl parathion (MP) as a representative of OPs. Having been connected to the transducer system designed to work through an Arduino microcontroller, the biosensor could detect MP as efficiently as the conventional methods, with the detection limit of 0.1 μM, the lowest value ever reported for this method. It was stable at 25 °C for 30 days, could function 100 rounds repetitively, and yielded high recovery with real samples. Hence, this simply designed MPH-GST biosensor could be an easy and inexpensive alternative for efficient OP screening at site to help control its contamination.

Microfluidics for Environmental Applications

Microfluidic and lab-on-a-chip systems have become increasingly important tools across many research fields in recent years. As a result of their small size and precise flow control, as well as their ability to enable in situ process visualization, microfluidic systems are increasingly finding applications in environmental science and engineering. Broadly speaking, their main present applications within these fields include use as sensors for water contaminant analysis (e.g., heavy metals and organic pollutants), as tools for microorganism detection (e.g., virus and bacteria), and as platforms for the investigation of environment-related problems (e.g., bacteria electron transfer and biofilm formation). This chapter aims to review the applications of microfluidics in environmental science and engineering - with a particular focus on the foregoing topics. The advantages and limitations of microfluidics when compared to traditional methods are also surveyed, and several perspectives on the future of research and development into microfluidics for environmental applications are offered.

Enzyme-based optical biosensors for organophosphate class of pesticide detection

A systematic review of enzyme based optical detection schemes for the detection and analysis of organophosphate pesticides has been presented.

Amphiphilic Polymer-Mediated Aggregation-Induced Emission Nanoparticles for Highly Sensitive Organophosphorus Pesticide Biosensing

Biosensing applications require signal reporters to be sufficiently stable and biosafe as well as highly efficient. Aggregation-induced emission (AIE) nanoparticles have proven to be capable of cell-imaging and cancer therapy; however, realizing sensitive detection of biomolecules remains a great challenge because of their instability, biotoxicity, and lack of modifiable functional groups. Herein, we report a self-assembling strategy to fabricate AIE nanoparticles (PTDNPs) through the dispersion of amphiphilic polymers (PTDs) in phosphate-buffered saline. The PTDs were prepared through radical copolymerization of N-(1,2,2-triphenylvinyl)-4-acetylaniline and dimethyl diallyl ammonium chloride. We found that the particle size, morphology, functional groups, and fluorescence property of PTDNPs can be fine-tuned. Further, PTDNPs-0.10 were chosen as signal reporters to detect organophosphorus pesticides (OPs) with the aid of gold nanoparticles. Their sensing performance on OPs is superior to that using C-dot/quantum dot/rhodamine B as the signal reporter. This study not only provides new possibilities to fabricate novel AIE nanoparticles with exceptional properties, but also facilitates the AIE nanoparticle's application for target analyte biosensing.

Visual detection of mixed organophosphorous pesticide using QD-AChE aerogel based microfluidic arrays sensor

In this paper, we present a simple strategy to fabricate a sensitive fluorescence microfluidic sensor based on quantum dots (QDs) aerogel and acetylcholinesterase enzyme (AChE) for organophosphate pesticides (OPs) detection The detection is based on the change of fluorescence intensity of QDs aerogel, which will be partly quenched as a consequence of the hydrolytic reaction of acetylthiocholine (ATCh) catalyzed by the AChE, and then the fluorescence of QDs aerogel is recovered due to decreasing of the enzymatic activity in the presence of OPs. The QDs-AChE aerogel based microfluidic arrays sensor provided good sensitivity for rapid detection of OPs with a detection limit of 0.38 pM, while the detection range is from 10^-5 to 10^-12 M. Due to the result of random orientations of AChE in the 3D porous aerogel nano-structure, the sensor presents similar calibration curves to difference pesticides, which promises the ability of the sensor to monitor total OPs of mixture. This determination sensor shows a low detection limit, wide linear range, and highly accurate determination of total OPs and carbamate content. Finally, we show the proposed sensor can be used to monitor of simple OPs and mixture in spiked fruit samples. This novel QDs-AChE aerogel sensor has an extremely high sensitivity and large detection range, it is a promising tool for accurate, rapid and cost-effective detection of various OP residues on agricultural products.

Highly sensitive and selective determination of malathion in vegetable extracts by an electrochemical sensor based on Cu-metal organic framework

This article demonstrates the first application of a copper-based porous coordination polymer (BTCA-P-Cu-CP) as a carbon paste electrode (CPE) modifier for the detection of malathion. The electrochemical behavior of BTCA-P-Cu-CP/CPE was explored using cyclic voltammetry (CV) while chrono-amperometry methods were applied for the analytical evaluation of the sensor performance. Under optimized conditions, the developed sensor exhibited high reproducibility, stability, and wide dynamic range (0.6-24 nM) with the limits of detection and sensitivity equal to 0.17 nM and 5.7 µAnMcm^-1, respectively, based on inhibition signal measurement. Furthermore, the presence of common coexisting interfering species showed a minor change in signals (<4.4%). The developed sensor has been applied in the determination of malathion in spiked vegetable extracts. It exhibited promising results in term of fast and sensitive determination of malathion in real samples at trace level with recoveries of 91.0 to 104.4%. (RSDs < 5%, n = 3). A comparison of the two studied techniques showed that the HPLC technique is unable to detect malathion when the concentration is lower than 1.8 µM while 0.006 µM is detected with appropriate RSDs 0.2-5.2% (n = 3) by amperometric method. Due to the high sensitivity and selectivity, this new electrochemical sensor will be useful for monitoring trace malathion in real samples.

Quantum Dots Applied to Methodology on Detection of Pesticide and Veterinary Drug Residues

The pesticide and veterinary drug residues brought by large-scale agricultural production have become one of the issues in the fields of food safety and environmental ecological security. It is necessary to develop the rapid, sensitive, qualitative and quantitative methodology for the detection of pesticide and veterinary drug residues. As one of the achievements of nanoscience, quantum dots (QDs) have been widely used in the detection of pesticide and veterinary drug residues. In these methodology studies, the used QD-signal styles include fluorescence, chemiluminescence, electrochemical luminescence, photoelectrochemistry, etc. QDs can also be assembled into sensors with different materials, such as QD-enzyme, QD-antibody, QD-aptamer, and QD-molecularly imprinted polymer sensors, etc. Plenty of study achievements in the field of detection of pesticide and veterinary drug residues have been obtained from the different combinations among these signals and sensors. They are summarized in this paper to provide a reference for the QD application in the detection of pesticide and veterinary drug residues.

Development and Applications of Quantum Dot-based Molecularly Imprinted Polymer Composites for Optosensing of Carbofuran in Water

In this paper, quantum dot (QD)-based molecularly imprinted polymer (MIP) was fabricated and successfully utilized as a fluorescent probe for highly selective and sensitive detection of carbofuran in water samples. The MIPs were synthesized followed by a multi-step swelling and polymerization method, and then labeled with CdSe/ZnS QDs via gradual solvent evaporation. Then the prepared QDs-MIP microspheres were introduced to flow cytometry by virtue of their good dispersibility in water, and fast adsorption and desorption. Under optimized conditions, the fluorescence intensity of QDs-MIP decreased linearly with the increasing of carbofuran in the concentration range of 1 - 20 μg L^-1 (R² > 0.99) and it can detect down to 0.2 μg L^-1 of carbofuran. This method was simple, selective and applied successfully to the optosensing of trace carbofuran in water samples with good recoveries ranging from 94.1 ± 3.7 to 98.4 ± 4.5%.

Inkjet-Printing Enzyme Inhibitory Assay Based on Determination of Ejection Volume

An accurate, rapid, and cost-effective methodology for enzyme inhibitor assays is highly needed for large-scale screening to evaluate the efficacy of drugs at the molecular level. For the first time, we have developed an inkjet printing-based enzyme inhibition assay for the assessment of drug activity using a conventional inkjet printer composed of four cartridges. The methodology is based on the determination of the number of moles of the drug on the printed surface. The number of moles was quantified through the volume of substance ejected onto the printed surface. The volume ejected on the reaction spot was determined from the density of reagent ink solution and its weight loss after printing. A xanthine oxidase (XOD) inhibition assay was executed to quantitatively evaluate antioxidant activities of the drug based on the determination of the number of moles of the drug ejected by inkjet printing. The assay components of xanthine, nitro blue tetrazolium (NBT), superoxide dismutase (SOD)/drug, and XOD were printed systematically on A4 paper. A gradient range of the number of moles of SOD/drug printed on A4 paper could be successfully obtained. Because of the effect of enzyme activity inhibition, incrementally reduced NBT formazan colors appeared on the paper in a number-of-moles-dependent manner. The observed inhibitory mole (IM₅₀) values of tested compounds exhibited a similar tendency in their activity order, compared to the IC₅₀ values observed through absorption assay in well plates. Inkjet printing-based IM50 assessment consumed a significantly smaller reaction volume (by 2-3 orders of magnitude) and more rapid reaction time, compared to the well-plate-based absorption assay.

New biorecognition molecules in biosensors for the detection of toxins

Biological and synthetic recognition elements are at the heart of the majority of modern bioreceptor assays. Traditionally, enzymes and antibodies have been integrated in the biosensor designs as a popular choice for the detection of toxin molecules. But since 1970s, alternative biological and synthetic binders have been emerged as a promising alternative to conventional biorecognition elements in detection systems for laboratory and field-based applications. Recent research has witnessed immense interest in the use of recombinant enzymatic methodologies and nanozymes to circumvent the drawbacks associated with natural enzymes. In the area of antibody production, technologies based on the modification of in vivo synthesized materials and in vitro approaches with development of "display "systems have been introduced in the recent years. Subsequently, molecularly-imprinted polymers and Peptide nucleic acid (PNAs) were developed as an attractive receptor with applications in the area of sample preparation and detection systems. In this article, we discuss all alternatives to conventional biomolecules employed in the detection of various toxin molecules We review recent developments in modified enzymes, nanozymes, nanobodies, aptamers, peptides, protein scaffolds and DNazymes. With the advent of nanostructures and new interface materials, these recognition elements will be major players in future biosensor development.