Incorporation of thermally activated zeolite into carbon paste electrodes for voltammetric detection of carbendazim traces in milk samples

Electroanalytical overview: the sensing of carbendazim

Carbendazim is a broad-spectrum systemic fungicide that is used to control various fungal diseases in agriculture, horticulture, and forestry. Carbendazim is also used in post-harvest applications to prevent fungal growth on fruits and vegetables during storage and transportation. Carbendazim is regulated in many countries and banned in others, thus, there is a need for the sensing of carbendazim to ensure that high levels are avoided which can result in potential health risks. One approach is the use of electroanalytical sensors which present a rapid, but highly selective and sensitive output, whilst being economical and providing portable sensing platforms to support on-site analysis. In this minireview, we report on the electroanalytical sensing of carbendazim overviewing recent advances, helping to elucidate the electrochemical mechanism and provide conclusions and future perspectives of this field.

Improving the functionality of biodegradable food packaging materials via porous nanomaterials

Non-biodegradability and disposal problems are the major challenges associated with synthetic plastic packaging. This review article discusses a new generation of biodegradable active and smart packaging based on porous nanomaterials (PNMs), which maintains the quality and freshness of food products while meeting biodegradability requirements. PNMs have recently gained significant attention in the field of food packaging due to their large surface area, peculiar structures, functional flexibility, and thermal stability. We present for the first time the recently published literature on the incorporation of various PNMs into renewable materials to develop advanced, environmentally friendly, and high-quality packaging technology. Various emerging packaging technologies are discussed in this review, along with their advantages and disadvantages. Moreover, it provides general information about PNMs, their characterization, and fabrication methods. It also briefly describes the effects of different PNMs on the functionality of biopolymeric films. Furthermore, we examined how smart packaging loaded with PNMs can improve food shelf life and reduce food waste. The results indicate that PNMs play a critical role in improving the antimicrobial, thermal, physicochemical, and mechanical properties of natural packaging materials. These tailor-made materials can simultaneously extend the shelf life of food while reducing plastic usage and food waste.

Photoinduced Electron Transfer-Triggered g-C3N4\Rhodamine B Sensing System for the Ratiometric Fluorescence Quantitation of Carbendazim

Assays for carbendazim (Car) with high sensitivity and on-site screening have been urgently required to protect the ecosystem and prevent disease. In this work, a simple, sensitive, and reliable sensing system based on photoinduced electron transfer was established to detect carbendazim utilizing ultrathin graphitic carbon nitride (g-C₃N₄) nanosheets and rhodamine B (RB). Carbendazim reacts with g-C₃N₄ by electrostatic interactions to form π-π stacking, and the quenching of the blue fluorescence is caused by electron transfer. While RB works as a reference fluorescence sensor without any fluorescence change, leading to obvious ratiometric fluorescence variation from blue to purple. Under optimal conditions, a favorable linear range from 20 to 180 nM was obtained, with a low detection limit of 5.89 nM. In addition, a portable smartphone sensing platform was successfully used for carbendazim detection in real samples with excellent anti-interference capability, demonstrating the potential applications of carbendazim monitoring.

Electrochemical Methods for the Analysis of Milk

The milk and dairy industries are some of the most profitable sectors in many countries. This business requires close control of product quality and continuous testing to ensure the safety of the consumers. The potential risk of contaminants or degradation products and undesirable chemicals necessitates the use of fast, reliable detection tools to make immediate production decisions. This review covers studies on the application of electrochemical methods to milk (i.e., voltammetric and amperometric) to quantify different analytes, as reported over the last 10 to 15 years. The review covers a wide range of analytes, including allergens, antioxidants, organic compounds, nitrogen- and aldehyde containing compounds, biochemicals, heavy metals, hydrogen peroxide, nitrite, and endocrine disruptors. The review also examines pretreatment procedures applied to milk samples and the use of novel sensor materials. Final perspectives are provided on the future of cost-effective and easy-to-use electrochemical sensors and their advantages over conventional methods.

A novel electrochemical sensor based on β-cyclodextrin functionalized carbon nanosheets@carbon nanotubes for sensitive detection of bactericide carbendazim in apple juice

Carbendazim (CBZ) abuse always causes the over-standard of pesticide residues in agricultural products, which has adverse effects on human health. Herein, a novel electrochemical sensor was firstly fabricated based on the β-cyclodextrin (β-CD) functionalized carbon nanosheets@carbon nanotubes (CNS@CNT) for the CBZ determination. CNS@CNT combined large surface area of CNS and excellent electrical conductivity of CNT, which significantly enhanced the electrocatalytic performance. Moreover, β-CD possessed excellent host-gest supramolecular recognition ability, which could improve the selective recognition and enrichment capability of CBZ. Thanks to the synergistic interaction of CNS@CNT and β-CD, the β-CD/CNS@CNT/GCE sensor exhibited a low limit of detection of 9.4 nM in the linear CBZ concentration range of 0.03-30 μM. The fabricated sensor presented favorable stability, high sensitivity (30.86 μA μM^-1 cm^-2), and reliable reproducibility (RSD = 3.6%). Especially, the β-CD/CNS@CNT/GCE sensor could show pretty practical feasibility for the detection of CBZ in apple juice with recoveries of 97.1%-99.4%.

Electro-Oxidation of Ammonia over Copper Oxide Impregnated γ-Al2O3 Nanocatalysts

Ammonia electro-oxidation (AEO) is a zero carbon-emitting sustainable means for the generation of hydrogen fuel, but its commercialization is deterred due to sluggish reaction kinetics and the poisoning of expensive metal electrocatalysts. With this perspective, CuO impregnated γ-Al2O3 (CuO/γ-Al2O3) hybrid materials were synthesized as effective and affordable electrocatalysts and investigated for AEO in alkaline media. Structural investigations were performed via different characterization techniques, i.e., X-ray diffraction (XRD), Fourier transformed infrared spectroscopy (FTIR), scanning electron microscopy (SEM), transmission electron microscopy (TEM), and electrochemical impedance spectroscopy (EIS). The morphology of γ-Al2O3 support as interconnected porous structures rendered the CuO/γ-Al2O3 nanocatalysts with robust activity. The additional CuO impregnation resulted in the enhanced electrochemical active surface area (ECSAs) and diffusion coefficient and spiked the electrocatalytic performance for NH3 electrolysis. Owing to good values of diffusion coefficient for AEO, low bandgap, and availability of ample ECSA at higher CuO to γ-Al2O3 ratio, these proposed electrocatalysts were proved to be effective in AEO. Due to good reproducibility, electrochemical stability, and higher activity for ammonia electro-oxidation, CuO/γ-Al2O3 nanomaterials are proposed as efficient promoters, electrode materials, or catalysts in ammonia electrocatalysis.

Study of the interaction Cu(II) - Carbendazim in natural waters by electrochemical techniques

In order to obtain higher agricultural yields, the use of chemical substances has been increased to prevent the proliferation of pests, as well as ensuring durability in the storage of the food produced. Such substances are known as pesticides that may well present risks to human health and the environment. In the presence of metal ions, these substances can interact forming new species with different characteristics. Carbendazim (MBC) is an example of a harmful pesticide, which has atoms of nitrogen and oxygen in its structure that can form complexes with metal ions. Thus, in this work has studied the interaction between the copper (II) metal ion and carbendazim and its formation in natural water. The Cu-MBC complex showed a reduction peak of 0.007 V and an oxidation peak of 0.500 V, with characteristics of a quasi-reversible process under a glassy carbon electrode. By anodic stripping voltammetry, a different behavior was observed in the interaction of copper and carbendazim in ultrapure water and Billings dam water; however, it was possible to observe the complex in both samples. Carbendazim in the presence of the metal shows lower oxidation potential value, indicating the influence of the metal on the electrochemical response of the pesticide.

Synthesizing of a nanocomposite based on the formation of silver nanoparticles on fumed silica to develop an electrochemical sensor for carbendazim detection

In this study, a nanocomposite was synthesized via the formation of silver nanoparticles on fumed silica (FS@Ag) to prepare an electrochemical sensor for the determination of carbendazim (CBZ), a common pesticide. The electrochemical sensor was designed by the combination of the carbon paste electrode (CPE) with the FS@Ag nanocomposite. Based on the electrochemical sensor prepared here, a voltammetric method was developed for the determination of CBZ in water and food samples. Characterization of the nanocomposite was conducted by X-ray diffraction, scanning electron microscopy, and energy-dispersive X-ray analyses. Modified electrodes were also electrochemically characterized via cyclic voltammetry and electrochemical impedance spectroscopy analyses. The FS@Ag showed electrocatalytic activity on the electrochemical oxidation of CBZ via increasing the peak currents tremendously. With the proposed method, a very low limit of detection (9.4 × 10^-10 M) and a wide linear range (5.0 × 10^-8 M - 3.0 × 10^-6 M) were obtained for CBZ. The slope of the calibration line obtained with CPE/15FS@Ag was 194-times higher than that of bare CPE, indicating the high sensitivity of the electrochemical sensor. The performance of the electrochemical sensor has been investigated in real samples such as river water, tomato juice, orange juice, and apple juice samples. The results reveal that the electrochemical sensor prepared here can be used as an alternative to current analytical methods used for the quantification of CBZ.

Synthesis of Au nanorod-embedded and graphene oxide-wrapped microporous ZIF-8 with high electrocatalytic activity for the sensing of pesticides

Multifunctional metal-organic framework-based composites display great potentials as electrode materials. Herein, highly dispersed Au nanorods were successfully encapsulated inside the zeolitic imidazolate framework ZIF-8 (AuNRs@ZIF-8) by epitaxial growth or nucleus coalescence. The microporous ZIF-8 shell functions as a protective coating to effectively prevent AuNRs from dissolution, aggregation, and migration during the electrochemical testing, while it provides numerous channels for the mass transfer of reactants to the AuNR surface. The as-synthesized AuNRs@ZIF-8 was then encapsulated in graphene oxide (GO) nanosheets to enhance the chemical resistance of the multicore-shell support, which possesses permanent porosity as well as high specific surface area and hydrophilicity. The excellent electrocatalytic performance of the resulting ternary AuNRs@ZIF-8@GO was demonstrated by the highly sensitive sensing of niclosamide, dichlorophen, carbendazim, and diuron, which outperformed the reported electrocatalysts for these four pesticides. This nanocomposite thus holds great promise as a catalyst for electrochemical sensor fabrication due to its abundant multiple active sites, enhanced catalytic activity, and remarkable stability.

Selection and Characterization of DNA Aptamers for Electrochemical Biosensing of Carbendazim

This article reports a novel aptamer-based impedimetric detection of carbendazim, a commonly used benzimidazole fungicide in agriculture. High affinity and specificity DNA aptamers against carbendazim were successfully selected using systematic evolution of ligand by exponential enrichment (SELEX). The dissociation constants (K_ds) of the selected DNA aptamers after 10 in vitro selection cycles were characterized using fluorescence-based assays showing values in the nanomolar range. The aptamer which showed the highest degree of affinity and conformation change was used to fabricate an electrochemical aptasensor via self-assembly of thiol-modified aptamer on gold electrodes. The aptasensor exploits the specific recognition of carbendazim by the aptamer immobilized on the gold surface which leads to conformational changes in the aptamer structure. This conformational change alters the access of a ferrocyanide/ferricyanide redox couple to the aptasensor surface. The aptasensor response is thus measured by following the increase in the electron transfer resistance of the redox couple using Faradaic electrochemical impedance spectroscopy. This method allowed a selective and sensitive label-free detection of carbendazim within a range of 10 pg/mL-10 ng/mL with a limit of detection of 8.2 pg/mL. The aptasensor did not show cross reactivity with other commonly used pesticides such as fenamiphos, isoproturon, atrazine, linuron, thiamethoxam, trifluralin, carbaryl, and methyl parathion. Moreover, the aptasensor has been applied in different spiked food matrixes showing high recovery percentages. We believe that the proposed aptasensor is a promising alternative to the currently used methods for carbendazim monitoring.