Portable electrochemical sensing methodologies for on-site detection of pesticide residues in fruits and vegetables

Electronic structure engineering of N-doped carbon nanozyme via incorporating Cl and sp3-hybridized defected carbon for organophosphorus pesticides assay

Metal-free carbon-based nanozymes often exhibit superior chemical stability and detection reliability compared to their metal-doped counterparts. However, their catalytic activity remains an area ripe for further enhancement. Herein, we successfully prepared a chlorine (Cl)-modified, metal-free, and porous N-doped carbon nanozyme (Clx-pNC) via NaCl molten etching. The incorporation of Cl induced an increase in the intrinsic defects of sp3-hybridized carbon within Clx-pNC and optimized the electronic structure of the N-connected carbon atoms. Remarkably, the peroxidase (POD)-like activity of Clx-pNC was enhanced twelvefold compared to porous N-doped carbon (pNC). Theoretical simulations highlighted that the introduction of Cl not only promoted H2O2 adsorption but also lowered the energy barrier for its decomposition, facilitating the generation of active intermediates and thus boosting POD-like activity. Based on the POD mimic activity of Clx-pNC, we developed a colorimetric platform for OPs detection utilizing a cascade amplification strategy. This work provides insights into the rational design of carbon-based nanozymes and the development of nanozyme-based colorimetric biosensors.

Portable multimodal platform with carbon nano-onions as colorimetric and fluorescent signal output for trypsin detection

Multimodal biosensors with independent signaling pathways can self-calibrate and improve the reliability of disease biomarker detection. Herein, a colorimetric-fluorescent dual-mode paper-based biosensor with PAN/Fe(III)-CNOs (FPCs) as core components has been developed, which information is recognized by smartphone and naked eye. Using 1-(2-pyridylazo)-2-naphthol (PAN) as a mediator, Fe(III) is enriched on the surface of carbon nano-onions (CNOs), endowing FPCs with excellent mimetic enzyme activity and photothermal conversion ability, which allows it to output amplified colorimetric signals under laser irradiation. In addition, the complexation of PAN with Fe(III) broadens its absorption spectrum, which makes FPCs more suitable to be energy acceptors to quench fluorescence of polymer dots (Pdots), resulting in the changes of output fluorescent signal. Based on the above design, a portable colorimetric-fluorescent dual-mode biosensor is proposed for trypsin detection with Pdots as fluorescence sources and FPCs as fluorescence quenchers and nanoenzymes. This work provides a convenient way for constructing portable visual multimodal biosensors, which is expected to applied in various disease diagnosis.

Single-atom oxide-decorated AuNPs for universal enhancement in SERS detection of pesticide residues

BACKGROUND

In the context of modern agriculture, the proliferation of chemical use calls for enhanced pesticide detection to safeguard food quality and public health. The development of accurate testing methodologies is imperative to mitigate the environmental impact of pesticides and ensure the integrity of ecosystems, thereby reflecting the pressing need for advancements in agricultural safety protocols. Therefore, the development of highly sensitive monitoring technology for detecting pesticide residues in agricultural products is necessary for safeguarding human health, ensuring food safety, and maintaining environmental sustainability.

RESULTS

Herein, a controllable surface charge on single tungsten atom-modified gold nanoparticles was used to create an electrostatic force with positively charged pesticide residues. Moreover, hydrogen bonds formed by single-atom sites can induce analyte-adsorbed nanoparticle aggregation, and the sizes of single-tungsten-atom-decorated AuNPs can maintain a gap between each other, resulting in improved SERS detection sensitivity through analyte enrichment at gold nanoparticle hotspots. In terms of the detection limits for pesticide residue analysis, we can effectively achieve an ultrahigh sensitivity of 0.1 ppb for acetamiprid, paraquat and carbendazim, which is among the best SERS sensitivities at the state of the art. For apple sample analysis, our work demonstrated good reproductivity (RSD<6 %) and a strong linear relationship (R2 ≥ 0.97) for 4 pesticide residues after optimizing the pretreatment process, which proves the enormous potential in quantitative analysis.

SIGNIFICANCE

Single-atom sites hotspot are firstly successfully achieved and uniformly dispersed between Au nanoparticle, which can effectively increase the sensitivity, keep stability of the Raman scattering signals and possess a significant improvement beyond that of undecorated hotspots when applied in pesticide residue detection. This method can be employed as a universal strategy to capture pesticide residues at hotspots for SERS detection.

Synergistic SERS enhancement of NiCo-LDHs microurchins and silver nanoparticles for ultra-sensitive and reusable detection of thiabendazole

Two-dimensional layered semiconductor materials as a distinctive class of materials are comprehensively explored for widespread applications due to narrow bandgap, controllable morphology, and tunable metal cation composition. Herein, we constructed a sensing platform of surface enhanced Raman spectroscopy (SERS) by combination of nickel‑cobalt layered double hydroxide (NiCo-LDH) microurchins and plasmonic silver nanoparticles (Ag NPs) for fungicide detection of thiabendazole (TBZ). The NiCo-LDHs/Ag-NPs microcomposites consist of NiCo-LDHs microurchins having a large number of nanoneedles deposited with photoreduced Ag NPs. The SERS platform with NiCo-LDHs/Ag-NPs shows an excellent SERS performance for TBZ detection, including an ultra-low detection limit of 1.49 × 10-11 M, a sublime enhancement factor of 1.71 × 109, high uniformity, good reproducibility, and long-term storage stability. The ultrahigh SERS activity of NiCo-LDH/Ag-NPs can be attributed to strong electromagnetic enhancement in the nanoscale gaps between Ag NPs, massive charge transfer through large-area NiCo-LDH/Ag-NPs interfaces, and the synergistic action of electromagnetic and charge transfer mechanisms. Besides, the unique morphology of NiCo-LDHs/Ag-NPs microcomposite provides a broad surface area for adsorption of TBZ molecules for further Raman signal enhancement. The practicability of the proposed SERS platform is confirmed by detecting TBZ in the real samples of apple juice and river water. The exceptional self-cleaning capability of the NiCo-LDHs/Ag-NPs microcomposite with an retention rate of 81.97 % even after the fifth degradation cycle underscores its impressive sustainable reusability and cost-effectiveness. The findings in this work lay the foundation for the development of high-performance SERS platforms to ensure food safety and environmental protection.

Emerging trends in functional materials for electrochemical sensors in nicotine determination

In the past year, there has been significant progress in the utilization of electrochemical strategies for the determination of harmful substances. Among those, the electrochemical determination of nicotine (NIC) has continued to be of significant interest ascribed to the global health concern of e-cigarette products, nowadays. Electrochemical sensors have become promising tools for the detection of NIC ascribed to their high sensitivity, selectivity, and ease of use. This review article provides a concise overview of the advanced developments in electrochemical sensors for NIC detection using modified functional materials such as carbon-based materials, metal-organic frameworks (MOF), MXene, polymer, and metallic based modifiers. The sensitivity of electrochemical sensors can be improved by modifying them with these conductive materials ascribed to their physical and chemical properties. The review also addresses the challenges and future perspectives in the field, including sensitivity and selectivity improvements, stability and reproducibility issues, integration with data analysis techniques, and emerging trends. In conclusion, this review article may be of interest to researchers intending to delve into the development of functional electrochemical sensors in future studies.

Dual lateral flow test for simple and rapid simultaneous immunodetection of bisphenol A and dimethyl phthalate, two priority plastic related environmental contaminants

Contamination of the environment by technogenic endocrine disrupting compounds (EDCs) becomes serious threat to public health. To effectively prevent this threat, it is necessary to improve analytical methods for EDCs to ensure mass, fast and productive monitoring. In the given work, a dual lateral flow test (LFT) is developed in the first time for simultaneous immunodetection of bisphenol A and dimethyl phthalate, priority EDCs releasing from plastic and belonging to different chemical classes. It combines integrated detection of two EDCs by one analytical system with rapidity and simplicity of LFTs allowing for off-lab testing without additional reagents and devices. Gold nanoparticles differing in shape and color (red gold nanospheres and blue gold nanoflowers) are applied as markers to simplify interpretation of the obtained results. Under the optimal conditions chosen for efficient control of the both analytes, the detection limits of bisphenol A and dimethyl phthalate are 0.67 ng/mL and 2.22 ng/mL, respectively. Time of the assay is 15 min. The proposed dual LFT has confirmed its practical applicability by analyzing natural water samples with recovery of bisphenol A and dimethyl phthalate in the ranges of 90.4-107.0% and 86.8-118.0%, respectively.

Graphene-based electrochemical sensors for antibiotics: sensing theories, synthetic methods, and on-site monitoring applications

Owing to the extensive use of antibiotics for treating infectious diseases in livestock and humans, the resulting residual antibiotics are a burden to the ecosystem and human health. Hence, for human health and ecological safety, it is critical to determine the residual antibiotics with accuracy and convenience. Graphene-based electrochemical sensors are an effective tool to detect residual antibiotics owing to their advantages, such as, high sensitivity, simplicity, and time efficiency. In this work, we comprehensively summarize the recent advances in graphene-based electrochemical sensors used for detecting antibiotics, including modifiers for electrode fabrication, theoretical elaboration of electrochemical sensing mechanisms, and practical applications of portable electrochemical platforms for the on-site monitoring of antibiotics. It is anticipated that the current review will be a valuable reference for comprehensively comprehending graphene-based electrochemical sensors and further promoting their applications in the fields of healthcare, environmental protection, and food safety.

Portable Miniature Mass Spectrometry for Enhanced On-Site Detection of Analytes in Complex Samples by Integrating Solid-Phase Microextraction and Nano-Electrospray Ionization

On-site mass spectrometry (MS) analysis plays a crucial role in timely understanding chemical compositions of field samples but presents a challenge to miniaturization, portability, and sensitivity. In this work, a portable MS approach was developed by integrating biocompatible solid-phase microextraction (SPME) and a nano-electrospray ionization (nESI) emitter into a kit to couple miniature MS (mMS). The SPME fiber was used for on-site extractive sampling of analytes from complex liquid samples and living organisms and was then inserted into an nESI emitter for on-site MS analysis via the facile kit. The limit of detection was found to be at the pg/mL level for various compounds tested. Acceptable relative standard deviation (RSD) values (5.5-7.6%, n = 6) were obtained for direct measurement of analytes in complex matrixes; acceptable linear responses (0.1-50 ng/mL) and matrix effects (76.0-82.6%) were also found. Enhanced detection of compounds of interest in various real samples, such as food samples, human fluids, environmental water, and living organisms, was unambiguously demonstrated. Our experimental data showed that SPME-nESI-mMS is a promising tool for on-site analysis of various complex samples in significant applications including but not limited to food safety, environmental monitoring, forensic investigation, and bioanalysis.

Bioreceptors' immobilization by hydrogen bonding interactions and differential pulse voltammetry for completely label-free electrochemical biosensors

Label-free electrochemical biosensors show great potential for the development of point-of-care devices (POCDs) for environmental and clinical applications. These sensors operate with shorter analysis times and are more economic than the labelled ones. Here, four completely label-free biosensors without electron transfer mediators were developed for hepatitis B virus (HBV) detection. The approach consisted in (i) the modification of gold surfaces with cysteamine (CT) or cysteine (CS) linkers, (ii) the subsequent antibody (Ab) immobilization, either directly by hydrogen bonding (HB) interactions or by covalent bonds (CB) using additional reagents, and (iii) measuring the biosensor response by electrochemical impedance spectroscopy (EIS) and differential pulse voltammetry (DPV). The electrode surfaces at each stage of the modification process were characterised by X-ray photo-electron spectroscopy (XPS) and atomic force microscopy (AFM). The combination of Ab immobilization by HB with the DPV analysis displayed improved repeatability, lower interference to serum matrix and similar limits of detection and quantification than the traditional biosensors that immobilize the Ab via CB and use EIS as readout technique. The Ab immobilization by HB is shown as a simple, efficient and low-cost alternative to CB ones, while DPV was faster and showed better performance than EIS. The CT-HB biosensor displayed the lowest limits of detection and quantification of 0.14 and 0.46 ng/mL, respectively, a 0.46-12.5 ng/mL linear analytical range, and 100% of recovery for 1/10 human serum media during HBV surface antigen detection by DPV. Even, it preserved the initial sensing capability after 7 days of its fabrication.

Multi-confinement structured carbon dots with long room temperature phosphorescence lifetime and efficiency for sensing thiram residues assisted by copper ions

Room temperature phosphorescent carbon dots (NCCDs@SiO2) were obtained by encapsulating hydrothermally synthesized CDs in a dense Si-O network structure after high-temperature calcination using silica as the matrix. This can avoid the quenching effect of dissolved oxygen in water and has a phosphorescence lifetime of up to 2.41 s. Using the phosphorescence property of NCCDs@SiO2, a phosphorescence quenching sensor was developed for the sensitive and selective detection of thiram with the assistance of Cu2+. Cu2+-thiram complexes led to a rapid phosphorescence quenching of NCCDs@SiO2 within 30 s through the inner filter effect. The linear range of phosphorescence for thiram was 0.5-100 µM with a detection limit of 0.121 µM. The proposed method was able to detect thiram in real samples and was validated by high-performance liquid chromatography (HPLC) confirming the potential of this phosphorescence sensing method for thiram detection. This work opens up a new avenue for the detection of thiram residues in fruits and vegetables and also provides a new idea for the design of a rapid detection platform using other room temperature phosphorescent materials.

A purine fluorescent derived probe assay for glyphosate and mesotrione via Schiff base cleavage

A fluorescent probe derived from purine with Schiff base moiety was developed for the recognization of glyphosate and mesotrione. The detected glyphosate and mesotrione can lead to the dissociation of the Schiff base probe to enhance the fluorescence via a turn-off PET process. Mechanism study revealed that the synergistic effect of the phosphoric acid and the secondary amine moieties in glyphosate results in the bond cleavage of the Schiff base probe. Quantitative measurements of glyphosate and mesotrione were achieved with the detection limits of 17.2 nM and 484.32 nM, respectively. Meanwhile, the detection of glyphosate pesticide in real samples and cells was also conducted, demonstrating the good practicality and cytocompatibility of the probe.

Surface-Initiated Reversible Addition-Fragmentation Chain Transfer Polymerization (SI-RAFT) to Produce Molecularly Imprinted Polymers on Graphene Oxide for Electrochemical Sensing of Methylparathion

A nonenzymatic redox-responsive sensor was put forward for the detection of methylparathion (MP) by designing globular nanostructures of molecularly imprinted polymers on graphene oxide (GO@MIPs) via surface-initiated reversible addition-fragmentation chain transfer polymerization (SI-RAFT). Fourier transform infrared (FTIR) spectroscopy, field emission scanning electron microscopy (FESEM), and small-angle X-ray scattering (SAXS) studies have confirmed the successful formation of receptor layers of MIPs on RAFT agent-functionalized GO sheets. The electrochemical signal with an amplified current response was attained because of the enhanced diffusion rate of ions at the interface provided by widening the pore size of the MIP film. The analytical response of GO@MIPs, validated by recording square-wave anodic stripping voltammetry (SWASV) at varying MP concentrations, followed the linear response between 0.2 and 200 ng/mL. Under optimized conditions, the sensor exhibited a limit of detection of 4.25 ng/mL with high selectivity over other interfering ions or molecules. The anti-interfering ability and good recovery (%) in food samples directed the use of the proposed sensor toward real-time monitoring and also toward future mimicking of surfaces.

Are Aptamer-Based Biosensors the Future of the Detection of the Human Gut Microbiome?-A Systematic Review and Meta-Analysis

The gut microbiome is shaped early in life by dietary and lifestyle factors. Specific compounds in the gut affect the growth of different bacterial species and the production of beneficial or harmful byproducts. Dysbiosis of the gut microbiome has been linked to various diseases resulting from the presence of harmful bacteria and their byproducts. Existing methods for detecting microbial species, such as microscopic observation and molecular biological techniques, are costly, labor-intensive, and require skilled personnel. Biosensors, which integrate a recognition element, transducer, amplifier, signal processor, and display unit, can convert biological events into electronic signals. This review provides a comprehensive and systematic survey of scientific publications from 2018 to June 2024, obtained from ScienceDirect, PubMed, and Scopus databases. The aim was to evaluate the current state-of-the-art and identify knowledge gaps in the application of aptamer biosensors for the determination of gut microbiota. A total of 13 eligible publications were categorized based on the type of study: those using microbial bioreceptors (category 1) and those using aptamer bioreceptors (category 2) for the determination of gut microbiota. Point-of-care biosensors are being developed to monitor changes in metabolites that may lead to disease. They are well-suited for use in the healthcare system and offer an excellent alternative to traditional methods. Aptamers are gaining attention due to their stability, specificity, scalability, reproducibility, low production cost, and low immunogenicity. While there is limited research on using aptamers to detect human gut microbiota, they show promise for providing accurate, robust, and cost-effective diagnostic methods for monitoring the gut microbiome.

Metal-organic framework-based aptasensor utilizing a novel electrochemiluminescence system for detecting acetamiprid residues in vegetables

The work was based on N-(4-Aminobutyl)-N-ethylisoluminol (ABEI)-functionalized Fe-MIL-101 and gold nanoparticles (AuNPs) as sensing materials, and an electrochemiluminescence (ECL) aptasensor was constructed for detecting acetamiprid. As a metal-organic framework (MOF) material, Fe-MIL-101, was renowned for its unique three-dimensional network structure and efficient catalytic capability. ABEI, a common ECL reagent, was widely applied. ABEI was introduced into the Fe-MIL-101 structure as a luminescence functionalization reagent to form Fe-MIL-101@ABEI. This approach avoided limitations on the loading capacity of luminescent reagents imposed by modification and encapsulation methods. With character of excellent catalytic activity and ease of bioconjugation, AuNPs offered significant advantages in biosensing. Leveraging the reductive properties of ABEI, AuNPs were reduced around Fe-MIL-101@ABEI, resulting in the modified luminescent functionalized material denoted as Fe-MIL-101@ABEI@AuNPs. An aptamer was employed as a recognition element and was modified accordingly. The aptamer was immobilized on Fe-MIL-101@ABEI@AuNPs through gold-sulfur (Au-S) bonds. After capturing acetamiprid, the aptamer induced a decrease in the ECL signal intensity within the ABEI-hydrogen peroxide (H2O2) system, enabling the quantitative detection of acetamiprid. The aptasensor displayed remarkable stability and repeatability, featured a detection range of 1×10-3-1×102 nM, and had a limit of detection (LOD) of 0.3 pM (S/N=3), which underscored its substantial practical application potential.

Panoramic view of artificial fruit ripening agents sensing technologies and the exigency of developing smart, rapid, and portable detection devices: A review

Recently, the availability of point-of-care sensor systems has led to the rapid development of smart and portable devices for the detection of hazardous analytes. The rapid flow of artificially ripened fruits into the market is associated with an elevated risk to human life, agriculture, and the ecosystem due to the use of artificial fruit ripening agents (AFRAs). Accordingly, there is a need for the development of "Point-of-care Sensors" to detect AFRAs due to several advantages, such as simple operation, promising detection mechanism, higher selectivity and sensitivity, compact, and portable. Traditional detection approaches are time-consuming and inappropriate for on-the-spot analyses. Presented comprehensive review aimed to reveal how such technology has systematically evolved over time (through conventional, advanced, and portable smart techniques) detection detect AFRA, till date. Moreover, focuses and highlights a framework of initiatives undertaken for technological advancements in the development of smart the portable detection techniques (kits) for the onsite detection of AFRAs in fruits with in-depth discussion over sensing mechanism and analytical performance of the sensing technology. Notably, colorimetric detection methods have the greatest potential for real-time monitoring of AFRA and its residues because they are easy to assemble, have a high level of selectivity and sensitivity, and can be read by the human eye independently. This study sought to differentiate between traditional credible strategies by presenting new prospects, perceptions, and challenges related to portable devices. This review provides systematic framework of advances in portable field recognition strategies for the on-spot AFRA detection in fruits and critical information for development of new paper-based portable sensors for fruit diagnostic sectors.

Recent advances in portable devices for environmental monitoring applications

Environmental pollution remains a major societal problem, leading to serious impacts on living organisms including humans. Human activities such as civilization, urbanization, and industrialization are major causes of pollution. Imposing stricter rules helps control environmental pollutant levels, creating a need for reliable pollutant monitoring in air, water, and soil. The application of traditional analytical techniques is limited in low-resource areas because they are sophisticated, expensive, and bulky. With the development of biosensors and microfluidics technology, environmental monitoring has significantly improved the analysis time, low cost, portability, and ease of use. This review discusses the fundamentals of portable devices, including microfluidics and biosensors, for environmental control. Recently, publications reviewing microfluidics and biosensor device applications have increased more than tenfold, showing the potential of emerging novel approaches for environmental monitoring. Strategies for enzyme-, immunoassay-, and molecular-based analyte sensing are discussed based on their mechanisms and applications. Microfluidic and biosensor platforms for detecting major pollutants, including metal ions, pathogens, pesticides, and antibiotic residues, are reviewed based on their working principles, advantages, and disadvantages. Challenges and future trends for the device design and fabrication process to improve performance are discussed. Miniaturization, low cost, selectivity, sensitivity, high automation, and savings in samples and reagents make the devices ideal alternatives for in-field detection, especially in low-resource areas. However, their operation with complicated environmental samples requires further research to improve the specificity and sensitivity. Although there is a wide range of devices available for environmental applications, their implementation in real-world situations is limited. This study provides insights into existing issues that can be used as references and a comparative analysis for future studies and applications.

Research Progress of Biosensor Based on Organic Photoelectrochemical Transistor

In order to solve the food safety problem better, it is very important to develop a rapid and sensitive technology for detecting food contamination residues. Organic photoelectrochemical transistor (OPECT) biosensor rely on the photovoltage generated by a semiconductor upon excitation by light to regulate the conductivity of the polymer channels and realize biosensor analysis under zero gate bias. This technology integrates the excellent characteristics of photoelectrochemical (PEC) bioanalysis and the high sensitivity and inherent amplification ability of organic electrochemical transistor (OECT). Based on this, OPECT biosensor detection has been proven to be superior to traditional biosensor detection methods. In this review, we summarize the research status of OPECT biosensor in disease markers and food residue analysis, the basic principle, classification, and biosensing mechanism of OPECT biosensor analysis are briefly introduced, and the recent applications of biosensor analysis are discussed according to the signal strategy. We mainly introduced the OPECT biosensor analysis methods applied in different fields, including the detection of disease markers and food hazard residues such as prostate-specific antigen, heart-type fatty acid binding protein, T-2 toxin detection in milk samples, fat mass and objectivity related protein, ciprofloxacin in milk. The OPECT biosensor provides considerable development potential for the construction of safety analysis and detection platforms in many fields, such as agriculture and food, and hopes to provide some reference for the future development of biosensing analysis methods with higher selectivity, faster analysis speed and higher sensitivity.

Electrochemistry as a Powerful Tool for Investigations of Antineoplastic Agents: A Comprehensive Review

Cancer is most frequently treated with antineoplastic agents (ANAs) that are hazardous to patients undergoing chemotherapy and the healthcare workers who handle ANAs in the course of their duties. All aspects related to hazardous oncological drugs illustrate that the monitoring of ANAs is essential to minimize the risks associated with these drugs. Among all analytical techniques used to test ANAs, electrochemistry holds an important position. This review, for the first time, comprehensively describes the progress done in electrochemistry of ANAs by means of a variety of bare or modified (bio)sensors over the last four decades (in the period of 1982-2021). Attention is paid not only to the development of electrochemical sensing protocols of ANAs in various biological, environmental, and pharmaceutical matrices but also to achievements of electrochemical techniques in the examination of the interactions of ANAs with deoxyribonucleic acid (DNA), carcinogenic cells, biomimetic membranes, peptides, and enzymes. Other aspects, including the enantiopurity studies, differentiation between single-stranded and double-stranded DNA without using any label or tag, studies on ANAs degradation, and their pharmacokinetics, by means of electrochemical techniques are also commented. Finally, concluding remarks that underline the existence of a significant niche for the basic electrochemical research that should be filled in the future are presented.

Smartphone-Based Techniques Using Carbon Dot Nanomaterials for Food Safety Analysis

The development of portable and efficient nanoprobes to realize the quantitative/qualitative onsite determination of food pollutants is of immense importance for safeguarding human health and food safety. With the advent of the smartphone, the digital imaging property causes it to be an ideal diagnostic substrate to point-of-care analysis probes. Besides, merging the versatility of carbon dots nanostructures and bioreceptor abilities has opened an innovative assortment of construction blocks to design advanced nanoprobes or improving those existing ones. On this ground, massive endeavors have been made to combine mobile phones with smart nanomaterials to produce portable (bio)sensors in a reliable, low cost, rapid, and even facile-to-implement area with inadequate resources. Herein, this work outlines the latest advancement of carbon dots nanostructures on smartphone for onsite detecting of agri-food pollutants. Particularly, we afford a summary of numerous approaches applied for target molecule diagnosis (pesticides, mycotoxins, pathogens, antibiotics, and metal ions), for instance microscopic imaging, fluorescence, colorimetric, and electrochemical techniques. Authors tried to list those scaffolds that are well-recognized in complex media or those using novel constructions/techniques. Lastly, we also point out some challenges and appealing prospects related to the enhancement of high-efficiency smartphone based carbon dots systems.

A review of smart electrochemical devices for pesticide detection in agricultural food and runoff contaminants

In the evolving field of food and agriculture, pesticide utilization is inevitable for food production and poses an increasing threat to the ecosystem and human health. This review systematically investigates and provides a comprehensive overview of recent developments in smart electrochemical devices for detecting pesticides in agricultural food and runoff contaminants. The focus encompasses recent progress in lab-scale and portable electrochemical sensors, highlighting their significance in agricultural pesticide monitoring. This review compares these sensors comprehensively and provides a scientific guide for future sensor development for infield agricultural pesticide monitoring and food safety. Smart devices address challenges related to power consumption, low cost, wearability, and portability, contributing to the advancement of agricultural sustainability. By elucidating the intricate details of these smart devices, this review offers a comprehensive discussion and roadmap for future research aimed at cost-effective, flexible, and smart handy devices, including novel electrocatalysts, to foster the development of next-generation agricultural sensor technology, opportunity and future direction for food security.

Sensitive fluorescence detection of glyphosate and glufosinate ammonium pesticides by purine-hydrazone-Cu2+ complex

Organophosphorus pesticides play an important role as broad-spectrum inactivating herbicides in agriculture. Developing a method for rapid and efficient organophosphorus pesticides detection is still urgent due to the increasing concern on food safety. An organo-probe (ZDA), synthesized by purine hydrazone derivative and 2,2'-dipyridylamine derivative, was applied in sensitive recognition of Cu2+ with detection limit of 300 nM. Mechanism study via density functional theory (DFT) and job's plot experiment revealed that ZDA and Cu2+ ions form a 1:2 complex quenching the fluorescence emission. Moreover, this fluorescent complex ZDA-Cu2+ was applicable for detecting glyphosate and glufosinate ammonium following fluorescence enhancement mechanism, with detection limits of 11.26 nM and 11.5 nM, respectively. Meanwhile, ZDA-Cu2+ was effective and sensitive when it is used for pesticide detection, reaching the maximum value and stabilizing in 1 min. Finally, the ZDA-Cu2+ probe could also be tolerated in cell assay environment, implying potential bio-application.

An Updated Review on Functionalized Graphene as Sensitive Materials in Sensing of Pesticides

Numerous chemical pesticides were employed for a long time to manage pests, but their uncontrolled application harmed the health and the environment. Accurately quantifying pesticide residues is essential for risk evaluation and regulatory purposes. Numerous analytical methods have been developed and utilized to achieve sensitive and specific detection of pesticides in intricate sampl es like water, soil, food, and air. Electrochemical sensors based on amperometry, potentiometry, or impedance spectroscopy offer portable, rapid, and sensitive detection suitable for on-site analysis. This study examines the potential of electrochemical sensors for the accurate evaluation of various effects of pesticides. Emphasizing the use of Graphene (GR), Graphene Oxide (GO), Reduced Graphene Oxide (rGO), and Graphdiyne composites, the study highlights their enhanced performance in pesticide sensing by stating the account of many actual sensors that have been made for specific pesticides. Computational studies provide valuable insights into the adsorption kinetics, binding energies, and electronic properties of pesticide-graphene complexes, guiding the design and optimization of graphene-based sensors with improved performance. Furthermore, the discussion extends to the emerging field of biopesticides. While the GR/GO/rGO based sensors hold immense future prospects, and their existing limitations have also been discussed, which need to be solved with future research.

Rapid smartphone-based assays for pesticides inspection in foods: current status, limitations, and future directions

Smartphone-based assays to inspect pesticides in foods have attracted much attention as such assays can transform tedious laboratory-based assays into real-time, on-site, or even home-based assay and hence overcoming the limitations of conventional assays. Although an array of smartphone-based assays is available, information on the use of these assays for pesticides inspection is scattered. The purposes of this review are therefore to compile, summarize and discuss state-of-the-art as well as advantages and limitations of the relevant technologies. Suggestions are provided for further development of smartphone-based assays for rapid inspection of pesticides in foods. Smartphone-based assays relying on enzyme inhibitions are noted to be nonselective qualitative, capable of reporting results in a quantitative manner only when a sample contains an individual pesticide. Smartphone-based assays relying on chemical reactions also target only individual pesticides. Smartphone-based visible spectroscopy can, on the other hand, inspect individual and multiple pesticides with the aid of appropriate colorimetry-, luminescence-, or fluorescence-based assay. Smartphone-based visible-near infrared and Raman spectroscopies are suitable for simultaneous multiple pesticides inspection. Raman spectroscopy is of particular interest as it can detect pesticides even at lower concentrations. This spectroscopic technique can also serve as a real-time assay with the aid of cloud network computations.

Seamless integration of Internet of Things, miniaturization, and environmental chemical surveillance

IoT is a game-changer across all fields, including chemistry. Embracing sustainable practices and green chemistry, the miniaturization and automation of systems, and their integration into IoT is key to achieving these principles, as a rising trend with momentum. Particularly, IoT and analytical chemistry are linked in the rapid exchange of analytical data for environmental, industrial, healthcare, and educational applications. Meanwhile, cooperation with other fields of science is evident, and there is a prompt and subjective analysis of information related to analytical systems and methodologies. This paper will review the concepts, requirements, and architecture of IoT and its role in the miniaturization and automation of analytical tools using electronic modules and sensors. The aim is to explore the standards and perspectives of IoT and its interaction with different aspects of analytical chemistry. Additionally, it aimed to explain the basics and applications of IoT for chemists, and its relevance to different subfields of analytical chemistry, particularly in the field of environmental chemical surveillance. The article also covers updating IoT devices and creating DIY-based degradation devices to enhance the educational aspect of chemistry and reduce barriers to lab facilities and equipment. Lastly, it will explore how IoT is really important and how it's going to significantly impact analytical chemistry.

Integrating Wireless Remote Sensing and Sensors for Monitoring Pesticide Pollution in Surface and Groundwater

Water constitutes an indispensable resource crucial for the sustenance of humanity, as it plays an integral role in various sectors such as agriculture, industrial processes, and domestic consumption. Even though water covers 71% of the global land surface, governments have been grappling with the challenge of ensuring the provision of safe water for domestic use. A contributing factor to this situation is the persistent contamination of available water sources rendering them unfit for human consumption. A common contaminant, pesticides are not frequently tested for despite their serious effects on biodiversity. Pesticide determination in water quality assessment is a challenging task because the procedures involved in the extraction and detection are complex. This reduces their popularity in many monitoring campaigns despite their harmful effects. If the existing methods of pesticide analysis are adapted by leveraging new technologies, then information concerning their presence in water ecosystems can be exposed. Furthermore, beyond the advantages conferred by the integration of wireless sensor networks (WSNs), the Internet of Things (IoT), Machine Learning (ML), and big data analytics, a notable outcome is the attainment of a heightened degree of granularity in the information of water ecosystems. This paper discusses methods of pesticide detection in water, emphasizing the possible use of electrochemical sensors, biosensors, and paper-based sensors in wireless sensing. It also explores the application of WSNs in water, the IoT, computing models, ML, and big data analytics, and their potential for integration as technologies useful for pesticide monitoring in water.

Integrated surface-enhanced Raman spectroscopy and convolutional neural network for quantitative and qualitative analysis of pesticide residues on pericarp

Pesticide residue poses a significant global public health concern, necessitating improved detection methods. Here, a novel platform was introduced based on surface-enhanced Raman spectroscopy (SERS) to detect ten distinct types of pesticides. Notably, the sensitivity of this approach is exemplified by detecting trace amounts of 50 pM (10 ppt) thiabendazole. The correlation between the characteristic peak intensity of coexisting pesticides and their concentrations displays an exceptional linear relationship (R2 = 0.9999), underscoring its utility for quantitative mixed pesticide detection. Additionally, qualitative analysis of five mixed pesticides was conducted leveraging distinctive peak labeling. Harnessing machine learning techniques, a model for classifying and predicting pesticides on pericarps was developed. Remarkably, the convolutional neural network achieved classification accuracy of 100 % and prediction accuracy of 99.62 %. This innovative approach accurately identifies and quantifies diverse pesticides, thus offering a feasible scheme for in-situ detection of pesticide residues. Ultimately, this strategy contributes to ensuring food safety and public health.

Portable and Flexible Hydrogel Sensor for On-Site Atrazine Assay on Agricultural Products

There is growing attention focused toward the problems of ecological sustainability and food safety raised from the abuse of herbicides, which underscores the need for the development of a portable and reliable sensor for simple, rapid, and user-friendly on-site analysis of herbicide residues. Herein, a novel multifunctional hydrogel composite is explored to serve as a portable and flexible sensor for the facile and efficient analysis of atrazine (ATZ) residues. The hydrogel electrode is fabricated by doping graphite-phase carbon nitride (g-C3N4) into the aramid nanofiber reinforced poly(vinyl alcohol) hydrogel via a simple solution-casting procedure. Benefiting from the excellent electroactivity and large specific surface area of the solid nanoscale component, the prepared hydrogel sensor is capable of simple, rapid, and sensitive detection of ATZ with a detection limit down to 0.002 ng/mL and per test time less than 1 min. After combination with a smartphone-controlled portable electrochemical analyzer, the flexible sensor exhibited satisfactory analytical performance for the ATZ assay. We further demonstrated the applications of the sensor in the evaluation of the ATZ residues in real water and soil samples as well as the user-friendly on-site point-of-need detection of ATZ residues on various agricultural products. We envision that this flexible and portable sensor will open a new avenue on the development of next-generation analytical tools for herbicide monitoring in the environment and agricultural products.

Molecularly Imprinted Polymer-Based Electrochemical Sensor for the Detection of Azoxystrobin in Aqueous Media

This work presents an electrochemical sensor detecting a fungicide-azoxystrobin (AZO) in aqueous environments. This AZO sensor utilizes a thin-film metal electrode (TFME) combined with an AZO-selective molecularly imprinted polymer (AZO-MIP). The AZO-MIP was directly generated on TFME through electrochemical polymerization from the solution containing two functional monomers: aniline (Ani) and m-phenylenediamine (mPD), and the template: AZO, which was afterwards removed to form AZO-selective cavities in the polymer matrix. The AZO-MIP preparation was characterized by electrochemical and ellipsometry measurements. Optimization of the synthesis parameters, including the charge density applied during electrodeposition, the monomer-to-template ratio, was performed to enhance the sensor's performance. The results demonstrated that the AZO sensor achieved a low limit of detection (LOD) of 3.6 nM and a limit of quantification (LOQ) of 11.8 nM in tap water, indicating its sensitivity in a complex aqueous environment. The sensor also exhibited satisfactory selectivity for AZO in both ultrapure and tap-water samples and achieved a good recovery (94-119%) for the target analyte. This study highlights the potential of MIP-based electrochemical sensors for the rapid and accurate detection of fungicide contaminants in water, contributing to the advancement of analytical tools for water-quality monitoring and risk assessment.

Pesticides impacts on human health and the environment with their mechanisms of action and possible countermeasures

Pesticides are chemical constituents used to prevent or control pests, including insects, rodents, fungi, weeds, and other unwanted organisms. Despite their advantages in crop production and disease management, the use of pesticides poses significant hazards to the environment and public health. Pesticide elements have now perpetually entered our atmosphere and subsequently contaminated water, food, and soil, leading to health threats ranging from acute to chronic toxicities. Pesticides can cause acute toxicity if a high dose is inhaled, ingested, or comes into contact with the skin or eyes, while prolonged or recurrent exposure to pesticides leads to chronic toxicity. Pesticides produce different types of toxicity, for instance, neurotoxicity, mutagenicity, carcinogenicity, teratogenicity, and endocrine disruption. The toxicity of a pesticide formulation may depend on the specific active ingredient and the presence of synergistic or inert compounds that can enhance or modify its toxicity. Safety concerns are the need of the hour to control contemporary pesticide-induced health hazards. The effectiveness and implementation of the current legislature in providing ample protection for human health and the environment are key concerns. This review explored a comprehensive summary of pesticides regarding their updated impacts on human health and advanced safety concerns with legislation. Implementing regulations, proper training, and education can help mitigate the negative impacts of pesticide use and promote safer and more sustainable agricultural practices.

Smart and emerging point of care electrochemical sensors based on nanomaterials for SARS-CoV-2 virus detection: Towards designing a future rapid diagnostic tool

In the recent years, researchers from all over the world have become interested in the fabrication of advanced and innovative electrochemical and/or biosensors for respiratory virus detection with the use of nanotechnology. These fabricated sensors demonstrated a number of benefits, including precision, affordability, accessibility, and miniaturization which makes them a promising test method for point-of-care (PoC) screening for SARS-CoV-2 viral infection. In order to comprehend the principles of electrochemical sensing and the role of various types of sensing interfaces, we comprehensively explored the underlying principles of electroanalytical methods and terminologies related to it in this review. In addition, it is addressed how to fabricate electrochemical sensing devices incorporating nanomaterials as graphene, metal/metal oxides, metal organic frameworks (MOFs), MXenes, quantum dots, and polymers. We took an effort to carefully compile current developments, advantages, drawbacks, possible solutions in nanomaterials based electrochemical sensors.

Inner filter effect-based upconversion nanosensor for rapid detection of thiram pesticides using upconversion nanoparticles and dithizone-cadmium complexes

Herein, we propose a method for detecting thiram based on the fluorescence inner filter effect using upconversion nanoparticles and dithizone-cadmium complexes (DZ-Cd2+). The ultraviolet absorption of DZ-Cd2+ was in the range of 480-600 nm under alkaline conditions, resulting in fluorescence quenching of the nanoparticles at 540 nm. Thiram had a stronger coordination effect with Cd2+ than dithizone; thus, more thiram-cadmium complex (T-Cd2+) formed when thiram was added, leading to fluorescence recovery at 540 nm. The standard thiram curve was found to have a detection limit of 6.75 ng/mL in the linear range of 0.01-1000 µg/mL. In addition, high-performance liquid chromatography results for detecting thiram in apple samples revealed good application performance. The results demonstrate that the developed method has great potential to detect thiram residues in food.

Portable sensors equipped with smartphones for organophosphorus pesticides detection

Organophosphorus pesticides (OPs) play an important role in agricultural production and the accurate detection of OP residues is essential to ensure food safety. Portable sensors are expected to be a potential device due to their high detection efficiency, easy-to-use processes and low cost. Due to the widespread popularity and powerful capabilities of smartphones, smartphone-based sensing systems have rapidly developed into ideal tools for portable detection, however, a systematic review on the detection of OPs is still lacking. Therefore, a comprehensive overview of sensors equipped with smartphones for OP detection in recent year is provided; this overview includes their sensing signals (colorimetric, fluorescent, chemiluminescent and electrochemical signals), detection mechanism, analysis applications, advantages/disadvantages and perspectives. Moreover, the progress of sensors equipped with smartphones for the detection of OPs in food is thoroughly summarized. This review contributes to food safety and the development of efficient and reliable methods for smartphone-based OPs detection.

Detection of Perfluorooctanoic and Perfluorodecanoic Acids on a Graphene-Based Electrochemical Sensor Aided by Computational Simulations

Perfluoroalkyl carboxylic acids (PFCAs) exhibit high chemical and thermal stability, rendering them versatile for various applications. However, their notable toxicity poses environmental and human health concerns. Detecting trace amounts of these chemicals is crucial to mitigate risks. Electrochemical sensors surpass traditional methods in sensitivity, selectivity, and cost-effectiveness. In this study, a graphene nanosheet-based sensor was developed for detecting perfluorooctanoic acid (PFOA) and perfluorodecanoic acid (PFDA). Using the Hummer method, graphene nanosheets were synthesized and characterized in terms of morphology, structural ordering, and surface topology. Ab initio molecular dynamics simulations determined the molecular interaction of per- and poly-fluoroalkyl substances (PFASs) with the sensor material. The sensor exhibited high sensitivity (50.75 μA·μM-1·cm-2 for PFOA and 29.58 μA·μM-1·cm-2 for PFDA) and low detection limits (10.4 nM for PFOA and 16.6 nM for PFDA) within the electrode dynamic linearity range of 0.05-500.0 μM (PFOA) and 0.08-500.0 μM (PFDA). Under optimal conditions, the sensor demonstrated excellent selectivity and recovery in testing for PFOA and PFDA in environmental samples, including spiked soil, water, spoiled vegetables, and fruit samples.

Fabrication of cellulose nanocrystals/carboxymethyl cellulose/zeolite membranes for methylene blue dye removal: understanding factors, adsorption kinetics, and thermodynamic isotherms

This study introduces environmentally-friendly nanocellulose-based membranes for AZO dye (methylene blue, MB) removal from wastewater. These membranes, made of cellulose nanocrystals (CNCs), carboxymethyl cellulose (CMC), zeolite, and citric acid, aim to offer eco-friendly water treatment solutions. CNCs, obtained from sugarcane bagasse, act as the foundational material for the membranes. The study aims to investigate both the composition of the membranes (CMC/CNC/zeolite/citric acid) and the critical adsorption factors (initial MB concentration, contact time, temperature, and pH) that impact the removal of the dye. After systematic experimentation, the optimal membrane composition is identified as 60% CNC, 15% CMC, 20% zeolites, and 5% citric acid. This composition achieved a 79.9% dye removal efficiency and a 38.3 mg/g adsorption capacity at pH 7. The optimized membrane exhibited enhanced MB dye removal under specific conditions, including a 50 mg adsorbent mass, 50 ppm dye concentration, 50 mL solution volume, 120-min contact time, and a temperature of 25°C. Increasing pH from neutral to alkaline enhances MB dye removal efficiency from 79.9% to 94.5%, with the adsorption capacity rising from 38.3 mg/g to 76.5 mg/g. The study extended to study the MB adsorption mechanisms, revealing the chemisorption of MB dye with pseudo-second-order kinetics. Chemical thermodynamic experiments determine the Freundlich isotherm as the apt model for MB dye adsorption on the membrane surface. In conclusion, this study successfully develops nanocellulose-based membranes for efficient AZO dye removal, contributing to sustainable water treatment technologies and environmental preservation efforts.

A comprehensive exploration of tartrazine detection in food products: Leveraging fluorescence nanomaterials and electrochemical sensors: Recent progress and future trends

Azo dyes are widely used as food coloring agents because of their affordability and stability. Examples include brilliant blue, carmoisine, sunset yellow, allura red, and tartrazine (Tar), etc. Notably, Tar is often utilized in hazardous food goods. They are frequently flavoured and combined with food items, raising the likelihood and danger of exposure. Therefore, detecting Tar in food is crucial to prevent health risks. Fluorescence nanomaterials and electrochemical sensors, known for their high sensitivity, affordability, simplicity, and speed, have been widely adopted by researchers for Tar detection. This comprehensive paper delves into the detection of Tar in food products. It extensively covers the utilization of advanced carbon-based nanomaterials, including CDs, doped CDs, and functionalized CDs, for sensitive Tar detection. Additionally, the paper explores the application of electrochemical sensors. The paper concludes by addressing current challenges and prospects, emphasizing efforts to enhance sensitivity, and selectivity for improved food safety.

Investigation of pesticide residues level on commonly consumed leafy vegetables picked from the central market in Jeddah, Saudi Arabia

This study aimed to investigate the presence of pesticide residues in a variety of commonly consumed leafy vegetables, including Grape leaves, Lettuce, Arugula, Spinach, Purslane, Ocimum, Parsley, Jew's mallow, Celery, Coriander, and Mint. A total of 100 samples were collected from the Central Market of Jeddah, Kingdom of Saudi Arabia. Our methodology involved employing the Quick, Easy, Cheap, Effective, Rugged, and Safe (QuEChERS) extraction method in combination with Liquid Chromatography-Tandem Mass Spectrometry (LC-MS/MS) to analyze a comprehensive database of 237 distinct pesticides. The range for limit of detection (LOD) and limit of quantification (LOQ) of the method were 0.0001 to 0.0014 mg. Kg-1 and 0.0010 to 0.0064 mg. Kg-1 for tested pesticides, respectively. The recoveries were in the range of 70-172.9%, with a relative standard deviation (RSD) of less than 19.0% for all tested pesticides. The results revealed that 60% of the analyzed samples were free from pesticide residues, while 40% exhibited contamination with 17 different pesticide residues. Notably, the most prevalent pesticide detected was Triallate in the Ocimum samples, followed by Metalaxyl in Grape leaves, Mint, and Spinach, and Methomyl in Celery. Approximately 45% of the samples contained pesticide residues that fell below or were equal to the European Union Maximum Residue Levels (EU MRLs), while the remaining 55% exceeded these MRLs. Remarkably, high pesticide concentrations were observed in all Ocimum samples (Triallate, Pyridaben, Hexythiazox, Imidacloprid), 67% of Grape leaves (Metalaxyl, Azoxystrobin, Difenoconazole Isomer), and 40% of Celery (Azoxystrobin, Methomyl). In conclusion, this study sheds light on the contamination levels of commonly consumed domestically produced and purchased leafy vegetables in the Central Market of Jeddah. To ensure food safety and the well-being of consumers, we strongly recommend enhanced scientific assessments and continued monitoring of pesticide usage in agricultural practices.

Nanotechnology in precision agriculture: Advancing towards sustainable crop production

Nanotechnology offers many potential solutions for sustainable agroecosystem, including improvement in nutrient use efficiency, efficacy of pest management, and minimizing the adverse environmental effects of agricultural production. Herein, we first highlighted the integrated application of nanotechnology and precision agriculture for sustainable productivity. Application of nanoparticle mediated material and advanced biosensors in precision agriculture is only possible by nanochips or nanosensors. Nanosensors offers the measurement of various stresses, soil quality parameters and detection of heavy metals along with the enhanced data collection, enabling precise decision-making and resource management in agricultural systems. Nanoencapsulation of conventional chemical fertilizers (known as nanofertilizers), and pesticides (known as nanopesticides) helps in sustained and slow release of chemicals to soils and results in precise dosage to plants. Further, nano-based disease detection kits are popular tools for early and speedy detection of viral diseases. Many other innovative approaches including biosynthesized nanoparticles have been evaluated and proposed at various scales, but in fact there are some barriers for practical application of nanotechnology in soil-plant system, including safety and regulatory concerns, efficient delivery at field levels, and consumer acceptance. Finally, we outlined the policy options and actions required for sustainable agricultural productivity, and proposed various research pathways that may help to overcome the upcoming challenges regarding practical implications of nanotechnology.

High sensitivity, low-cost, and disposability: A novel screen-printed electrode developed for direct electrochemical detection of the antibiotic ceftriaxone

This study describes the development of a novel disposable and low-cost electrochemical platform for detecting the antibiotic ceftriaxone. The screen-printed electrode has been modified with a novel hybrid nanostructure containing silicon oxide (SiO2), zirconium oxide (ZrO2), and nitrogen-doped carbon quantum dots (Cdot-N). Different techniques like Fourier-transform infrared spectroscopy, Raman spectroscopy, and transmission electron microscopy characterized the hybrid nanostructure used in the sensor surface modifier material. The hybrid nanostructure showed an excellent synergistic effect that contributed to the oxidation reaction of ceftriaxone. The screen-printed electrode modified with SiO2/ZrO2/Cdot-N nanostructure presented high sensitivity with a detection limit of 0.2 nmol L-1 in the linear range of 0.0078-40.02 μmol L-1. The measurements have been performed by square wave voltammetry technique. Studies on real samples of synthetic urine, urine, and tap water showed 95%-105% recovery without applying any sample pretreatment. The sensor demonstrated excellent selectivity in the antibiotic ceftriaxone determination in the presence of possible interferences cationic, Na+, K+, Ca2+, Mg2+, Cu2+, Pb2+, Mn2+, Zn2+, Co2+, and biological, glucose, caffeine, uric acid, and ascorbic acid. The developed sensor becomes a selective, sensitive, and applicable tool in determining the antibiotic ceftriaxone.

Developments in food neonicotinoids detection: novel recognition strategies, advanced chemical sensing techniques, and recent applications

Neonicotinoid insecticides (NEOs) are a new class of neurotoxic pesticides primarily used for pest control on fruits and vegetables, cereals, and other crops after organophosphorus pesticides (OPPs), carbamate pesticides (CBPs), and pyrethroid pesticides. However, chronic abuse and illegal use have led to the contamination of food and water sources as well as damage to ecological and environmental systems. Long-term exposure to NEOs may pose potential risks to animals (especially bees) and even human health. Consequently, it is necessary to develop effective, robust, and rapid methods for NEOs detection. Specific recognition-based chemical sensing has been regarded as one of the most promising detection tools for NEOs due to their excellent selectivity, sensitivity, and robust interference resistance. In this review, we introduce the novel recognition strategies-enabled chemical sensing in food neonicotinoids detection in the past years (2017-2023). The properties and advantages of molecular imprinting recognition (MIR), host-guest recognition (HGR), electron-catalyzed recognition (ECR), immune recognition (IR), aptamer recognition (AR), and enzyme inhibition recognition (EIR) in the development of NEOs sensing platforms are discussed in detail. Recent applications of chemical sensing platforms in various food products, including fruits and vegetables, cereals, teas, honey, aquatic products, and others are highlighted. In addition, the future trends of applying chemical sensing with specific recognition strategies for NEOs analysis are discussed.

Sensitive determination of 4,6-dinitro-o-cresol based on a glassy carbon electrode modified with Zr-UiO-66 metal-organic framework entrapped FMWCNTs

A DNOC electrochemical sensor has been developed by using a composite of Zr-UiO-66 and FMWCNTs on a glassy carbon electrode (GCE) and using the differential pulse voltammetry technique. The synthesized materials were physico-chemically characterized by BET, PXRD, FTIR, TGA, EDX, and FESEM. Cyclic voltammetry showed that DNOC has three oxidation peaks at 0.03 V (RSD: 0.23%), 0.42 V (RSD: 0.21%), and 1.32 V (RSD: 0.32%) and three reduction peaks at - 0.20 V (RSD: 0.15%), - 0.82 V (RSD: 0.26%), and - 1.14 V (RSD: 0.19%) which follow a diffusion-controlled mechanism. Different parameters were optimized using differential pulse voltammetry and good linear ranges were found for the simultaneous detection of the three reduction peaks. For a specific concentration range of 0.1-50 μM, a limit of detection of 0.119 μM based on 3Sb/m was obtained. The interfering effects of five non-phenolic pesticides and five heavy metals were evaluated to highlight the selectivity of the developed sensor. It is the first report of an electrochemical DNOC sensor in which all three oxidation peaks are prominently visible. Ethion and chloropyriphos were found to inhibit the redox process of DNOC on the developed sensor platform Zr-UiO-66/FMWCNT/GCE. The sensor was successfully applied to DNOC determination in spiked potato samples and the results showed a standard deviation of less than 3%. The proposed method is expected to provide a novel platform for the quantitative determination of DNOC pesticides in vegetables.

Facile Synthesis of Platinum Nanoparticle-Embedded Reduced Graphene Oxide for the Detection of Carbendazim

In recent years, there has been a significant interest in the advancement of electrochemical sensing platforms to detect pesticides with high sensitivity and selectivity. Current research presents a novel approach utilising platinum nanoparticles (NPs) and reduced graphene oxide deposited on a glassy carbon electrode (Pt-rGO/GCE) for direct electrochemical measurement of carbendazim (CBZ). A straightforward one-step electrodeposition process was applied to prepare the Pt-rGO sensing platform. The incorporation of conductive rGO nanosheets along with distinctive structured Pt NPs significantly enhanced the effective electrode surface area and electron transfer of CBZ. Additionally, when exposed to 50 µM CBZ, Pt-rGO/GCE exhibited a higher current response compared to the bare electrode. Further investigations were performed to analyse and optimise the experimental parameters that could influence pesticide detection. Under the optimised conditions of pH 7 and 5 min of accumulation time, the Pt-rGO/GCE sensor showed a linear concentration detection range from 0.1 µM to 50 µM, with a detection limit of 3.46 nM. The fabricated sensor was successfully employed for CBZ detection in milk and tap water with 98.88% and 98.57% recovery, respectively. The fabricated sensor showed higher sensitivity and reproducibility, thus indicating the potential of this technology in the development of reliable sensors for the detection of CBZ or similar pesticides in forthcoming applications.

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.

Fabricating process-electrochemical property correlation of laser-scribed graphene and smartphone-based electrochemical platform for portable and sensitive biosensing

Laser-scribed graphene (LSG), a promising electrode material has attracted special research interest in recent years. Here, the fabricating process-electrochemical property correlation of laser-scribed graphene (LSG) devices was discussed emphatically and a pertinent optimization was performed to achieve better electroanalytical performance. Experiment results indicated that the laser scribing technique possessed great process latitude and reducing laser power and scribing speed facilitated fabricating high-quality graphene electrodes. Benefiting from its binder-free 3D porous network structure and high active/geometric area ratio, the optimized LSG electrode was superior to the screen-printed carbon electrode (SPCE) on electrochemical performance in the [Fe(CN)6]3-/4- redox system. Integrating the LSG electrode with a homemade hand-held detector, a portable electrochemical sensing platform with smartphone readout was developed. It realized a specific detection of H2O2 (linear range: 0.02-3.4 mM, sensitivity: 24.56 μA mM-1 cm-2), glucose (linear range: 0.04-4.0 mM, sensitivity: 16.35 μA mM-1 cm-2) by directly decorating biological enzymes without artificial redox mediator and featured a satisfactory comprehensive performance. The constructed immunosensor for tumor necrosis factor-α exhibited a wide linear range (2-500 pg mL-1) and a 4.3-fold enhancement in sensitivity compared with that of SPCE. With satisfactory selectivity, reproducibility, and sensitivity, the developed smartphone-based electrochemical sensing platform held great promise in accurate detection on the spot. This work also provided a significant reference for tailoring binder-free carbonaceous electrode materials toward the desired application.

Neuron-Inspired Nanofluidic Biosensors for Highly Sensitive and Selective Imidacloprid Detection

Pesticides have caused concerns about food safety due to their residual effects in vegetables and fruits. Imidacloprid, as the frequently used neonicotinoid pesticide, could harm cardiovascular and respiratory function and cause reproductive toxicity in humans. Therefore, reliable methods for portable, selective, and rapid detection are desirable to develop. Herein, we report a neuron-inspired nanofluidic biosensor based on a tyrosine-modified artificial nanochannel for sensitively detecting imidacloprid. The functional tyrosine is modified on the outer surface of porous anodic aluminum oxide to rapidly capture imidacloprid through π-π interactions and hydrogen bonds. The integrated nanofluidic biosensor has a wide concentration range from 10-8 to 10-4 g/mL with an ultralow detection limit of 6.28 × 10-9 g/mL, which outperforms the state-of-the-art sensors. This work provides a new perspective on detecting imidacloprid residues as well as other hazardous pesticide residues in environmental and food samples.

Emerging Insights into the Use of Advanced Nanomaterials for the Electrochemiluminescence Biosensor of Pesticide Residues in Plant-Derived Foodstuff

Pesticides have an important role in rising the overall productivity and yield of agricultural foods by eliminating and controlling insects, pests, fungi, and various plant-related illnesses. However, the overuse of pesticides has caused pesticide pollution of water bodies and food products, along with disruption of environmental and ecological systems. In this regard, developing low-cost, simple, and rapid-detecting approaches for the accurate, rapid, efficient, and on-site screening of pesticide residues is an ongoing challenge. Electrochemiluminescence (ECL) possesses the benefits of great sensitivity, the capability to resolve several analytes using different emission wavelengths or redox potentials, and excellent control over the light radiation in time and space, making it a powerful strategy for sensing various pesticides. Cost-effective and simple ECL systems allow sensitive, selective, and accurate quantification of pesticides in agricultural fields. Particularly, the development and progress of nanomaterials, aptamer/antibody recognition, electric/photo-sensing, and their integration with electrochemiluminescence sensing technology has presented the hopeful potential in reporting the residual amounts of pesticides. Current trends in the application of nanoparticles are debated, with an emphasis on sensor substrates using aptamer, antibodies, enzymes, and molecularly imprinted polymers (MIPs). Different strategies are enclosed in labeled and label-free sensing along with luminescence determination approaches (signal-off, signal-on, and signal-switch modes). Finally, the recent challenges and upcoming prospects in this ground are also put forward.

MXene@Au based electrochemical biosensor with pretreatment by magnetic nanoparticles for determination of MRSA from clinical samples

Pathogenic bacteria are associated with high morbidity rates and present significant diagnostic challenges in terms of rapid detection. This study introduces a magnetic separation-based electrochemical biosensor for the detection of Methicillin-resistant Staphylococcus aureus (MRSA). Vancomycin (Van) was used to modify on the surface of polyethyleneimine (PEI) mediated MBs (MBs-PEI-Van) for separation and enrichment of MRSA. The MBs-PEI-Van shown a satisfactory stability and applicability with capture effective (CE) > 85% in both PBS and cerebrospinal fluid (CSF) samples. MXene@Au with controllable size of AuNPs was synthesized by a self-reduction method and employed to modify the glassy carbon electrode (GCE). Immunoglobulin G (IgG) was loaded onto the modified electrode to immobilize MRSA, and ferroceneboronic acid (Fc-BA) was used as a probe for quantitative determination. The differential pulse voltammetry (DPV) current was plotted against the concentration of MRSA from 3.8 × 101 to 3.8 × 107 CFU/mL with a limit of detection (LOD) of 3.8 × 101 CFU/mL. In addition, MRSA was successfully detected in spiked CSF samples with satisfactory recoveries (94.35-107.81 %) and validation results (RSD < 11 %). Overall, this study presents a promising method for the detection of MRSA, with the potential to be further developed into a universal pathogen detection method.

Proximity-Driven DNA Nanosensors

In proximity-driven sensing, interactions between a probe and an analyte produce a detectable signal by causing a change in distance of two probe components or signaling moieties. By interfacing such systems with DNA-based nanostructures, platforms that are highly sensitive, specific, and programmable can be designed. In this Perspective, we delineate the advantages of using DNA building blocks in proximity-driven nanosensors and provide an overview of recent progress in the field, from sensors that rapidly detect pesticides in food to probes that identify rare cancer cells in blood. We also discuss current challenges and identify key areas that need further development.

Aerosol Jet Printing-Enabled Dual-Function Electrochemical and Colorimetric Biosensor for SARS-CoV-2 Detection

An aerosol jet printing-enabled dual-function biosensor for the sensitive detection of pathogens using SARS-CoV-2 RNA as an example has been developed. A CRISPR-Cas13:guide-RNA complex is activated in the presence of a target RNA, leading to the collateral trans-cleavage of ssRNA probes that contain a horseradish peroxidase (HRP) tag. This, in turn, catalyzes the oxidation of 3,3',5,5'-tetramethylbenzidine (TMB) by HRP, resulting in a color change and electrochemical signal change. The colorimetric and electrochemical sensing protocol does not require complicated target amplification and probe immobilization and exhibits a detection sensitivity in the femtomolar range. Additionally, our biosensor demonstrates a wide dynamic range of 5 orders of magnitude. This low-cost aerosol inkjet printing technique allows for an amplification-free and integrated dual-function biosensor platform, which operates at physiological temperature and is designed for simple, rapid, and accurate point-of-care (POC) diagnostics in either low-resource settings or hospitals.

Development of an electrochemical sensor based on ternary oxide SiO2/Al2O3/SnO2 modified with carbon black for direct determination of clothianidin in environmental and food samples

This study presents the development of an electrochemical sensor, denoted as GCE/CB/SiAlSn, based on the modification of a glassy carbon electrode surface with the ternary oxide SiO2/Al2O3/SnO2 associated with carbon black, for direct determination of the neonicotinoid pesticide clothianidin in different matrices, such as environmental and food samples. Morphological characterization by the scanning electron microscopy technique, electroanalytical analyses using the cyclic voltammetry technique and differential pulse voltammetry are presented which demonstrated that the developed electrochemical platform presents high sensitivity in the electroanalytical clothianidin determination. The linear range studied was from 2.99 × 10-7 to 6.04 × 10-5 mol L-1, with an LOD of 2.47 nmol L-1. This high sensitivity was explained using the synergistic relationship between carbon black and ternary oxide that maximized the electroactive surface area of the GCE/CB/SiAlSn sensor. Interferent studies were performed that showed high selectivity of the sensor to the pesticide in the presence of Ca2+, K+, Na+, and Mg2+ and carbendazim, glyphosate, imidacloprid and thiamethoxam pesticides. The sensor was applied to real samples of tap water and apple juice obtaining recoveries from 91.0% to 103.0%.