Electrochemical analysis of trifluralin using a nanostructuring electrode with multi-walled carbon nanotubes

Revisiting the Role of Sensors for Shaping Plant Research: Applications and Future Perspectives

Plant health monitoring is essential for understanding the impact of environmental stressors (biotic and abiotic) on crop production, and for tailoring plant developmental and adaptive responses accordingly. Plants are constantly exposed to different stressors like pathogens and soil pollutants (heavy metals and pesticides) which pose a serious threat to their survival and to human health. Plants have the ability to respond to environmental stressors by undergoing rapid transcriptional, translational, and metabolic reprogramming at different cellular compartments in order to balance growth and adaptive responses. However, plants' exceptional responsiveness to environmental cues is highly complex, which is driven by diverse signaling molecules such as calcium Ca2+, reactive oxygen species (ROS), hormones, small peptides and metabolites. Additionally, other factors like pH also influence these responses. The regulation and occurrence of these plant signaling molecules are often undetectable, necessitating nondestructive, live research approaches to understand their molecular complexity and functional traits during growth and stress conditions. With the advent of sensors, in vivo and in vitro understanding of some of these processes associated with plant physiology, signaling, metabolism, and development has provided a novel platform not only for decoding the biochemical complexity of signaling pathways but also for targeted engineering to improve diverse plant traits. The application of sensors in detecting pathogens and soil pollutants like heavy metal and pesticides plays a key role in protecting plant and human health. In this review, we provide an update on sensors used in plant biology for the detection of diverse signaling molecules and their functional attributes. We also discuss different types of sensors (biosensors and nanosensors) used in agriculture for detecting pesticides, pathogens and pollutants.

Recent Advances in Nanoparticle-Based Optical Sensors for Detection of Pesticide Residues in Soil

The excessive and unreasonable use of pesticides has adversely affected the environment and human health. The soil, one of the most critical natural resources supporting human survival and development, accumulates large amounts of pesticide residues. Compared to traditional spectrophotometry analytical methods, nanoparticle-based sensors stand out for their simplicity of operation as well as their high sensitivity and low detection limits. In this review, we focus primarily on the functions that various nanoparticles have and how they can be used to detect various pesticide residues in soil. A detailed discussion was conducted on the properties of nanoparticles, including their color changeability, Raman enhancement, fluorescence enhancement and quenching, and catalysis. We have also systematically reviewed the methodology for detecting insecticides, herbicides, and fungicides in soil by using nanoparticles.

Lab-on-fruit skin and lab-on-leaf towards recognition of trifluralin using Ag-citrate/GQDs nanocomposite stabilized on the flexible substrate: A new platform for the electroanalysis of herbicides using direct writing of nano-inks and pen-on paper technology

Trifluralin is herbicide of the dinitroanilines group in which NO₂ molecules are attached to the benzene ring at diverse positions. Trifluralin affects endocrine function and is listed as an endocrine disrupter in the European Union list. Therefore, its determination is so important in health science. In this study, an easy, sensitive and environmentally friendly method has been developed for determination of trifluralin based on its electrochemical oxidation on a three-electrode system designed on the surface of agricultural products using Ag-citrate/GQDs (graphene quantum dots) nano-ink. The sensor was prepared by direct writing on the surface of the samples. The designed electrodes were dried after 24 h at room temperature and used for trifluralin detection. Under optimized experimental conditions, the Ag-citrate/GQDs nano-ink based sensor was exhibited good sensitivity and specificity for trifluralin detection. The obtained linear range using the cyclic voltammetric (CV) technique is between 0.008 to 1 mM and low limit of quantification (LLOQ) was 0.008 mM. Also, the obtained linear range using differential pulse voltammetric (DPV) and square wave voltammetric (SWV) techniques is 0.005–0.04 mM with LLOQ of 0.005 mM. For further validation of the applicability of the proposed method, it was also used for detection of trifluralin on the surface of apple skin.

Voltammetric detection of trifluralin in tap water, fruit juice, and vegetable extracts in the presence of surfactants

This study describes a novel electrochemical method to determine the herbicide trifluralin in samples of water, fruit juice, and vegetable extracts in the presence of surfactants, using a glassy carbon electrode (GCE). In acidic media, trifluralin was irreversible on the glassy carbon electrode surface at -0.5 V vs. Ag/AgCl. Surfactant presence on the electrode-solution interface modified current intensities and shifted the reduction peak potential of trifluralin. Different types of surfactant and their concentrations were investigated. The anionic surfactant significantly enhanced the peak current intensity of trifluralin. Under optimal analytical conditions, an analytical curve was obtained in the concentration range of 0.48-32.20 µM. The limits of detection and quantification were estimated at 0.031 and 0.104 µM, respectively. The method was successfully applied to quantify trifluralin in samples of water, orange and tomato juice, and green pepper, carrot, and onion extracts, with recovery rates of 97.9-102.1%. The results were in good agreement with those obtained using high-performance liquid chromatography, indicating that the proposed electrochemical method can be employed to quantify trifluralin in various types foods, with sensitivity, specificity, selectivity and reproducibility.

A simple and sensitive method for the determination of 4-n-octylphenol based on multi-walled carbon nanotubes modified glassy carbon electrode

A simple and sensitive electroanalytical method was presented for the determination of 4-n-octylphenol (OP) based on multi-walled carbon nanotubes (MWCNTs) modified glassy carbon electrode (GCE). OP was directly oxidized on the MWCNTs/GCE, and the electrochemical oxidation mechanism was demonstrated by a one-electron and one-proton process in the reaction. The oxidation peak current of OP was significantly enhanced by the use of MWCNTs/GCE compared with those of bare glassy carbon electrode, suggesting that the modified electrode can remarkably improve the performance for OP determination. Factors influencing the detection processes were optimized. Under these optimal conditions, a linear relationship between concentration of OP and current response was obtained in the range of 5 x 10(-8) to 1 x 10(-5) mol/L with a detection limit of 1.5 x 10(-8) mol/L and correlation coefficient 0.9986. The modified electrode showed good selectivity, sensitivity, reproducibility and high stability.