A Label-Free Electrochemical Aptasensor Based on Zn/Fe Bimetallic MOF Derived Nanoporous Carbon for Ultra-Sensitive and Selective Determination of Paraquat in Vegetables

Portable label-free electrochemical aptasensor for sensitive detection of paraquat herbicide mediated by oxygen reduction reaction

Paraquat (PQ) is a highly toxic herbicide that has been prohibited in almost 70 countries, but remains in use worldwide. Thus, routine on-site PQ monitoring is a key mechanism to ensure safety and efficiently enforce regulations. Herein, a label-free portable electrochemical aptasensor for the detection of PQ was developed by utilizing aptamer designed to specifically recognize PQ. The aptasensor employs square-wave voltammetry (SWV) to quantify PQ binding on the aptamer-functionalized electrode surface by tracking the downstream oxygen reduction reaction. It provided a detection range spanning from 0.01 to 100.0 μg mL-1 PQ with a limit of detection (LOD) of 8.9 ng mL-1. Validation against spiked tap water, pomegranate juice, and orange juice revealed recovery rate performances of 75 %-130 %. The aptasensor demonstrates promising feasibility for PQ detection in real-world applications, offering remarkable portability and operational simplicity. Notably, it can operate without supplementary redox agents, requiring only sample incubation and subsequent washing steps.

Paraquat-Induced Toxicities: Epidemiological Insights and Advances in Colorimetric and Fluorimetric Detection Methods

Paraquat (PQ) is a potent and widely utilized herbicide known for its effectiveness in controlling a broad spectrum of weeds. Its chemical properties make it an invaluable tool in agriculture, where it helps maintain crop yields and manage invasive plant species. However, despite its benefits in weed management, PQ poses significant risks due to its severe toxicity, which affects multiple organ systems in both humans and animals. The dual nature of PQ, as both a valuable agricultural chemical and a hazardous toxicant, necessitates a comprehensive understanding of its toxicological impacts and the development of effective detection and development strategies. This review aims to provide a comprehensive overview of PQ-induced toxicities, including neurotoxicity, lung toxicity, liver toxicity, kidney toxicity, and immunotoxicity. By synthesizing current knowledge on PQ health impacts, highlighting epidemiological trends, and exploring recent advancements in colorimetric and fluorimetric detection methods, this review seeks to contribute to the development of strategies for improving public health outcomes and enhancing our ability to manage the risks associated with PQ exposure. Addressing PQ toxicity through a multidisciplinary approach, incorporating toxicological, epidemiological, and technological perspectives, is essential for safeguarding health and promoting effective interventions.

Simultaneous Determination of Aflatoxin B1 and Ochratoxin A in Cereals by a Novel Electrochemical Aptasensor Using Metal-Organic Framework as Signal Carrier

A novel electrochemical aptasensor was prepared for the simultaneous determination of aflatoxin B1 (AFB1) and ochratoxin A (OTA). Composites of Au nanoparticles and polyethyleneimine-reduced graphene oxide (AuNPs/PEI-RGO) with good electrical conductivity and high specific surface area were employed as the supporting substrate, demonstrating the ability to provide more binding sites for aptamers and accelerate the electron transfer. Aptamers were immobilized on a AuNPs/PEI-RGO surface to specifically recognize AFB1 and OTA. A metal-organic framework of UiO-66-NH2 served as the signal carrier to load metal ions of Cu2+ and Pb2+, which facilitated the generation of independent current peaks and effectively improved the electrochemical signals. The prepared aptasensor exhibited sensitive current responses for AFB1 and OTA with a linear range of 0.01 to 1000 ng/mL, with detection limits of 6.2 ng/L for AFB1 and 3.7 ng/L for OTA, respectively. The aptasensor was applied to detect AFB1 and OTA in cereal samples, achieving results comparable with HPLC-MS, with recovery results from 92.5% to 104.1%. With these merits of high sensitivity and good selectivity and stability, the prepared aptasensor proved to be a powerful tool for evaluating contaminated cereals.

Fluorescent chemosensors facilitate the visualization of plant health and their living environment in sustainable agriculture

Globally, 91% of plant production encounters diverse environmental stresses that adversely affect their growth, leading to severe yield losses of 50-60%. In this case, monitoring the connection between the environment and plant health can balance population demands with environmental protection and resource distribution. Fluorescent chemosensors have shown great progress in monitoring the health and environment of plants due to their high sensitivity and biocompatibility. However, to date, no comprehensive analysis and systematic summary of fluorescent chemosensors used in monitoring the correlation between plant health and their environment have been reported. Thus, herein, we summarize the current fluorescent chemosensors ranging from their design strategies to applications in monitoring plant-environment interaction processes. First, we highlight the types of fluorescent chemosensors with design strategies to resolve the bottlenecks encountered in monitoring the health and living environment of plants. In addition, the applications of fluorescent small-molecule, nano and supramolecular chemosensors in the visualization of the health and living environment of plants are discussed. Finally, the major challenges and perspectives in this field are presented. This work will provide guidance for the design of efficient fluorescent chemosensors to monitor plant health, and then promote sustainable agricultural development.

3D nanocake-like Au-MXene/Au pallet structure-based label-free electrochemical aptasensor for paraquat determination

3D nanocake-like Au-MXene and Au pallet (Au-MXene/AuP) nanocomposite-modified screen-printed carbon electrodes (SPCEs) were utilized to construct an ultrasensitive label-free electrochemical aptasensor through a self-assembly procedure for trace paraquat (PQ) residue detection. Benefiting from the excellent electrochemical (EC) performances (e.g., high conductivity and large surface area) of Au-MXene nanocomposites and AuP substrate, the developed Apt/Au-MXene/AuP/SPCE-based EC aptasensor displayed excellent specificity and anti-interference ability, good repeatability, and stability. A linear relationship between the log value of the change in current intensity [lg (ΔI)] and the log value of the concentration of PQ [lg (CPQ)] was obtained in the range 0.05-1000 ng/mL. The limit of detection was 0.028 ng/mL, and the sensitivity was 255.5 μA/(μM·cm2). Practical applications in malt and mint samples confirmed the accuracy of the EC aptasensor in complex matrices for PQ detection, providing a universal analytical tool for other trace pesticides in different food samples by simply replacing the corresponding aptamers.

Recent Advances in Electrochemical Biosensors for Food Control

The rapid and sensitive detection of food contaminants is becoming increasingly important for timely prevention and treatment of foodborne disease. In this review, we discuss recent developments of electrochemical biosensors as facile, rapid, sensitive, and user-friendly analytical devices and their applications in food safety analysis, owing to the analytical characteristics of electrochemical detection and to advances in the design and production of bioreceptors (antibodies, DNA, aptamers, peptides, molecular imprinted polymers, enzymes, bacteriophages, etc.). They can offer a low limit of detection required for food contaminants such as allergens, pesticides, antibiotic traces, toxins, bacteria, etc. We provide an overview of a broad range of electrochemical biosensing designs and consider future opportunities for this technology in food control.

Integration of Metallic Nanomaterials and Recognition Elements for the Specifically Monitoring of Pesticides in Electrochemical Sensing

Although all countries have been controlling the excessive use of pesticides, incidents of pesticide residues still existed. Electrochemical biosensors are extensively applied detection techniques to monitor pesticides with the help of different types of biorecognition components mainly including, antibodies, aptamers, enzymes (i.e., acetylcholinesterase, organophosphorus hydrolase, etc.), and synthetic molecularly imprinted polymers. Besides, the electrode materials mainly affected the sensitivity of electrochemical biosensors. Metallic nanomaterials with various structures and excellent electrical conductivity were desirable choice to construct electrochemical platforms to achieve the detection with high sensitivity and good specificity toward the target. This work reviewed the developed metallic materials including monometallic nanoparticles, bimetallic nanomaterials, metal atoms, metal oxides, metal molybdates, metal-organic frameworks, MXene, etc. Integration of recognition elements endowed the electrode materials with higher specificity toward the target pesticide. Besides, future challenges of metallic nanomaterials-based electrochemical biosensors for the detection of pesticides are also discussed and described.