Fabrication of thulium metal–organic frameworks based smartphone sensor towards arsenical feed additive drug detection: Applicable in food safety analysis

Electrochemical sensor for detecting roxarsone in animal-derived foods using MXene and silver telluride

Detecting harmful feed additives in animal-derived foods is essential due to potential health and environmental risks. Given its toxicity, Roxarsone, a common organoarsenic compound, requires sensitive detection methods. This study introduces an electrochemical sensor using a glassy carbon electrode modified with 2D MXene (Ti3C2Tₓ) layered with silver telluride (Ag2Te). Characterization through XRD, FT-IR, and XPS confirmed the sensor's composition. Electrochemical assessments using cyclic voltammetry and differential pulse voltammetry showed notable electron transfer and catalytic efficiency improvements. The sensor exhibited a broad detection range for roxarsone (0.03-2310 μM) with an ultra-low detection limit (0.32 nM) and demonstrated excellent reproducibility (RSD < 3 %), stability, and selectivity. Real sample analysis in meat products confirmed its practical application, achieving high recovery rates. This work offers a robust approach for roxarsone detection, employing MXene and Ag2Te's synergistic properties to enhance food safety and environmental monitoring.

Immunomagnetic metal-organic frameworks based coupling-free and extraction-free sensitive detection of aflatoxin B1 in peanut oils

Conventional AFB1 detection methods are hindered by cumbersome pretreatment procedures, primarily due to the lack of new sample pretreatment materials and technologies. This work developed a novel coupling-free synthesis strategy for the immunomagnetic metal-organic frameworks (IMMOFs), focusing on its effective and promising application in the extraction-free detection of AFB1. By coupling with UPLC-FLD, a sensitive quantification detection method for AFB1 was developed, exhibiting a linear range of 0.5 to 20 μg/kg and a detection limit of 0.1 μg/kg. The spiked recoveries at three concentrations ranged from 90.3 % to 97.9 %, with RSDs of less than 6 %. Moreover, the established method was successfully employed for analyzing AFB1 in naturally contaminated peanut oil samples, with results further confirmed by the traditional immunoaffinity column (IAC) method. This study provides an effective extraction-free detection technique for AFB1 that addresses the limitations of the traditional methods.

Synergistic innovation: MOF@GCN hybrid for electrochemical detection of flutamide-bridging experimental, computational, and real-world applications

Electrochemical sensors are at the forefront of analytical technology, offering remarkable sensitivity and rapid response for detecting a wide range of chemical and biological compounds. Herein, a bimetallic metal-organic framework (MOF) is engineered and combined with graphitic carbon nitride (GCN) to demonstrate exceptional electrochemical performance toward the anti-cancer drug flutamide. A simple solvothermal method is used to synthesize MOF and GCN. These materials are then used as precursors to synthesize the MOF@GCN nanocomposite via a sonication method. The formation of the nanocomposite is confirmed using various characterization techniques like UV-Vis spectroscopy, FTIR spectroscopy, XRD, XPS, TGA, SEM, and TEM. The electrochemical characterization is performed using EIS, and the electrochemical measurements are conducted using CV and LSV. The results obtained from the electrochemical parameters indicate good operational stability, high sensitivity, reliability, and excellent electrochemical conductivity. The LSV curves show linearity over a wide range of flutamide concentration levels (10 to 180 nM), a limit of detection of 17.56 nM, a limit of quantification of 53.23 nM, and an optimal sensitivity of 22.89 µA µM-1 cm-2. This electrical response of the sensor is attributed to the abundance of active sites, accelerated diffusion, and low rate of recombination. The real sample analysis conducted in biofluids and environmental samples also demonstrate good recovery for the flutamide analyte. The theoretical results obtained from the computational DFT analysis on the analyte are also in good agreement with the experimental results. In a wider perspective, the development of this electrochemical sensor promises significant advancements in health monitoring and environmental protection.

Terbium Vanadate Nanowires-Based Electrochemical Sensors for Mercury Ions

Terbium vanadate nanowires were synthesized via a facile chemical approach using sodium vanadate and terbium chloride. Morphology, structure, composition, and electrochemical characteristics of the terbium vanadate nanowires were investigated by different techniques. Terbium vanadate nanowires with single crystalline tetragonal TbVO4 phase possess smooth surface and flat tips. The length of the nanowires is longer than 5 μm, and diameter is 40-100 nm. Terbium vanadate nanowires modified electrode was used for trace-level mercury ions (Hg2+) detection. One well-defined stripping peak exists at - 0.34 V at the terbium vanadate nanowires modified electrode in 0.1 mM Hg2+ solution. Buffer solution pH value, deposition time, deposition potential, and standing time are pH = 1, 150 s, - 1.5 V, and 60 s, respectively. Detection limit for Hg2+ detection is 0.18 nM, and linear range is 0.01-100 μM. The proposed terbium vanadate nanowires modified electrode exhibits significant selectivity, stability, and reproducibility toward Hg2+. The usefulness of the developed sensor based on the terbium vanadate nanowires modified electrode was verified by Hg2+ detection in real samples.

Recent advancements in modifications of metal-organic frameworks-based materials for enhanced water purification and contaminant detection

Metal-organic frameworks (MOFs) have emerged as a key focus in water treatment and monitoring due to their unique structural features, including extensive surface area, customizable porosity, reversible adsorption, and high catalytic efficiency. While numerous reviews have discussed MOFs in environmental remediation, this review specifically addresses recent advancements in modifying MOFs to enhance their effectiveness in water purification and monitoring. It underscores their roles as adsorbents, photocatalysts, and in luminescent and electrochemical sensing. Advancements such as pore modification, defect engineering, and functionalization, combined synergistically with advanced materials, have led to the development of recyclable MOF-based nano-adsorbents, Z-scheme photocatalytic systems, nanocomposites, and hybrid materials. These innovations have broadened the spectrum of removable contaminants and improved material recyclability. Additionally, this review delves into the creation of multifunctional MOF materials, the development of robust MOF variants, and the simplification of synthesis methods, marking significant progress in MOF sensor technology. Furthermore, the review addresses current challenges in this field and proposes potential future research directions and practical applications. The growing research interest in MOFs underscores the need for an updated synthesis of knowledge in this area, focusing on both current challenges and future opportunities in water remediation.

Multifunctional Eu(III)-modified HOFs: roxarsone and aristolochic acid carcinogen monitoring and latent fingerprint identification based on artificial intelligence

The exploration of multifunctional materials and intelligent technologies used for fluorescence sensing and latent fingerprint (LFP) identification is a research hotspot of material science. In this study, an emerging crystalline luminescent material, Eu3+-functionalized hydrogen-bonded organic framework (Eu@HOF-BTB, Eu@1), is fabricated successfully. Eu@1 can emit purple red fluorescence with a high photoluminescence quantum yield of 36.82%. Combined with artificial intelligence (AI) algorithms including support vector machine, principal component analysis, and hierarchical clustering analysis, Eu@1 as a sensor can concurrently distinguish two carcinogens, roxarsone and aristolochic acid, based on different mechanisms. The sensing process exhibits high selectivity, high efficiency, and excellent anti-interference. Meanwhile, Eu@1 is also an excellent eikonogen for LFP identification with high-resolution and high-contrast. Based on an automatic fingerprint identification system, the simultaneous differentiation of two fingerprint images is achieved. Moreover, a simulation experiment of criminal arrest is conducted. By virtue of the Alexnet-based fingerprint analysis platform of AI, unknown LFPs can be compared with a database to identify the criminal within one second with over 90% recognition accuracy. With AI technology, HOFs are applied for the first time in the LFP identification field, which provides a new material and solution for investigators to track criminal clues and handle cases efficiently.

Voltammetric determination of doxycycline in feedstock using modified carbon screen-printed electrode

In this work, we describe the development of an electrochemical sensing platform that employs electrochemically reduced graphene oxide (ErGO) and gold (Au) deposited on a screen-printed carbon electrode (SPCE) to synthesize Au/ErGO/SPCE for the determination of the antibiotic drug doxycycline (DC). A modified Hummer's approach was adopted to initially prepare graphene oxide, which was then characterized by using powder XRD, FTIR, and UV spectroscopy before being utilized for modification on SPCE. Cyclic voltammetry was performed to form ErGO on SPCE to give ErGO/SPCE followed by electrodeposition of gold to get a final modified electrode Au/ErGO/SPCE. The effect of experimental conditions, like scan rate and pH on the electrochemical behavior of DC for Au/ErGO/SPCE, was evaluated. Square wave voltammetry (SWV) and cyclic voltammetry (CV) measurements were used to assess the electro-oxidation of DC on Au/ErGO/SPCE, and the electrochemical reaction conditions were also optimized. Furthermore, Au/ErGO/SPCE-based electrochemical sensors showed good recovery and high accuracy for DC determination in the complex food matrix and blood serum. The limit of detection (LOD), the limit of quantification (LOQ), and the linear calibration range of DC on Au/ErGO/SPCE under optimum experimental conditions were 0.124 µm, 0.415 µm, and 1-100 µm respectively, with high sensitivity of 0.194 μA μM-1 cm-2. Finally, the proposed electrochemical sensing platform was effectively used to determine low DC concentrations in real samples such as chicken flesh and blood serum, indicating its wide range of applications in quality control.

Current advances in the detection and removal of organic arsenic by metal-organic frameworks

Arsenic (As) is a highly toxic heavy metal and has been widely concerned for its hazardous environmental impact. Aromatic organic arsenic (AOCs) has been frequently used as an animal supplement to enhance feed utilization and prevent dysentery. The majority of organic arsenic could be discharged from the body and evolve as highly toxic inorganic arsenic that is hazardous to the environment and human health via biological conversion, photodegradation, and photo-oxidation. Current environmental issues necessitate the development and application of multifunctional porous materials in environmental remediation. Compared to the conventional adsorbent, such as activated carbon and zeolite, metal-organic frameworks (MOFs) exhibit a number of advantages, including simple synthesis, wide variety, simple modulation of pore size, large specific surface area, excellent chemical stability, and easy modification. In recent years, numerous scientists have investigated MOFs related materials involved with organic arsenic. These studies can be divided into three categories: detection of organic arsenic by MOFs, adsorption to remove organic arsenic by MOFs, and catalytic removal of organic arsenic by MOFs. Here, we conduct a critical analysis of current research findings and knowledge pertaining to the structural characteristics, application methods, removal properties, interaction mechanisms, and spectral analysis of MOFs. We summarized the application of MOFs in organic arsenic detection, adsorption, and catalytic degradation. Other arsenic removal technologies and conventional substances are also being investigated. This review will provide relevant scientific researchers with references.

Sensitive detection of Escherichia coli in diverse foodstuffs by electrochemical aptasensor based on 2D porphyrin-based COF

The two-dimensional porphyrin-based covalent organic framework (denoted by Tph-TDC-COF) was used as the sensitive layerto build an aptamer-based electrochemical sensor for the detection of Escherichia coli (E.coli). Tph-TDC-COF produced with 5,10,15,20-tetrakis(4-aminophenyl)-21H, 23H-porphine (Tph) and [2,2'-bithiophene]-2,5'-dicarbaldehyde (TDC) as building blocks exhibited a highly conjugated structure, outstanding conductivity, large specific surface area, and strong bioaffinity towards aptamers. The adoption of Tph-TDC-COF-modified electrode resulted in improved sensing performance and increased anchoring affinity toward the E.coli-targeted aptamer. Under optimal conditions, the Tph-TDC-COF-based electrochemical aptasensor demonstrated an extremely low detection limit of 0.17 CFU mL-1 for E.coli detection within a linear range of 10 to 1 × 108 CFU mL-1, accompanied by good stability, excellent reproducibility and regeneration ability, and wide practical applications. The current electrochemical aptasensing technique has the potential to be extended to detect different foodborne bacteria using specific aptamer, therefore widening the application of COFs in biosensing and food safety fields.

Diclofenac-Impregnated Mesoporous Carbon-Based Electrode Material for the Analysis of the Arsenic Drug Roxarsone

This paper describes a novel electrode material, diclofenac-impregnated mesoporous carbon modified with a cationic surfactant, cetyltrimethylammonium bromide (DF-CMK-3/CTAB), for ultratrace analysis of the arsenic drug roxarsone (ROX). DF-CMK-3 amorphous carbon is a material with a high specific surface area and well-defined, hexagonally ordered, thin mesopores. The functional groups attached to the carbonaceous surface, such as chromene and pyron-like oxygen groups, lactam, and aromatic carbon rings, have the basic character and they can donate electrons. Modification of DF-CMK-3 with a CTAB layer significantly increases the analytical signal due to electrostatic interactions between the cationic surfactant and the anion form of ROX in the acidic medium. The voltammetric procedure at the glassy carbon sensor modified with DF-CMK-3/CTAB exhibited excellent sensitivity (limit of detection of 9.6 × 10-11 M) with a wide range of linearity from 5.0 × 10-10 to 1.0 × 10-4 M. Analysis of real samples (treated municipal wastewater and river water) showed recoveries from 96 to 102% without applying the complicated sample pretreatment step. The sensor demonstrated excellent sensitivity in the analysis of the arsenic drug ROX in the presence of interferences in environmental water samples.

Covalent organic frameworks (COFs) and metal-organic frameworks (MOFs) as electrochemical sensors for the efficient detection of pharmaceutical residues

Pharmaceutical residues are the undecomposed remains from drugs used in the medical and food industries. Due to their potential adverse effects on human health and natural ecosystems, they are of increasing worldwide concern. The acute detection of pharmaceutical residues can give a rapid examination of their quantity and then prevent them from further contamination. Herein, this study summarizes and discusses the most recent porous covalent-organic frameworks (COFs) and metal-organic frameworks (MOFs) for the electrochemical detection of various pharmaceutical residues. The review first introduces a brief overview of drug toxicity and its effects on living organisms. Subsequently, different porous materials and drug detection techniques are discussed with materials' properties and applications. Then the development of COFs and MOFs has been addressed with their structural properties and sensing applications. Further, the stability, reusability, and sustainability of MOFs/COFs are reviewed and discussed. Besides, COFs and MOFs' detection limits, linear ranges, the role of functionalities, and immobilized nanoparticles are analyzed and discussed. Lastly, this review summarized and discussed the MOF@COF composite as sensors, the fabrication strategies to enhance detection potential, and the current challenges in this area.

A Portable Wireless Intelligent Nanosensor for 6,7-Dihydroxycoumarin Analysis with A Black Phosphorene and Nano-Diamond Nanocomposite-Modified Electrode

In this work, a novel portable and wireless intelligent electrochemical nanosensor was developed for the detection of 6,7-dihydroxycoumarin (6,7-DHC) using a modified screen-printed electrode (SPE). Black phosphorene (BP) nanosheets were prepared via exfoliation of black phosphorus nanoplates. The BP nanosheets were then mixed with nano-diamond (ND) to prepare ND@BP nanocomposites using the self-assembly method, achieving high environmental stability. The nanocomposite was characterized by SEM, TEM, Raman, XPS and XRD. The nanocomposite was used for the modification of SPE to improve its electrochemical performances. The nanosensor displayed a wide linear range of 0.01-450.0 μmol/L with a low detection limit of 0.003 μmol/L for 6,7-DHC analysis. The portable and wireless intelligent electrochemical nanosensor was applied to detect 6,7-DHC in real drug samples by the standard addition method with satisfactory recoveries, which extends the application of BP-based nanocomposite for electroanalysis.

Metal-organic frameworks for food contaminant adsorption and detection

Metal-organic framework materials (MOFs) have been widely used in food contamination adsorption and detection due to their large specific surface area, specific pore structure and flexible post-modification. MOFs with specific pore size can be targeted for selective adsorption of some contaminants and can be used as pretreatment and pre-concentration steps to purify samples and enrich target analytes for food contamination detection to improve the detection efficiency. In addition, MOFs, as a new functional material, play an important role in developing new rapid detection methods that are simple, portable, inexpensive and with high sensitivity and accuracy. The aim of this paper is to summarize the latest and insightful research results on MOFs for the adsorption and detection of food contaminants. By summarizing Zn-based, Cu-based and Zr-based MOFs with low cost, easily available raw materials and convenient synthesis conditions, we describe their principles and discuss their applications in chemical and biological contaminant adsorption and sensing detection in terms of stability, adsorption capacity and sensitivity. Finally, we present the limitations and challenges of MOFs in food detection, hoping to provide some ideas for future development.

Sonochemical construction of hierarchical strontium doped lanthanum trisulfide electrocatalyst: An efficient electrode for highly sensitive detection of ecological pollutant in food and water

Herbicides are used constantly in agriculture to enhance productivity across the globe. This herbicide monitoring requires utmost importance since its high dose leads to ecological imbalance and a negative impact on the environment. Moreover, a quantification of toxic herbicide is one of the important problems in the food analysis. In this work, deals with the development of a simple, and facile one-pot sonochemical synthesis of strontium doped La2S3 (Sr@La2S3). Morphological and structural characterization confirms the doping of Sr@La2S3 to generate a hierarchical layered structure. The electrochemical performance of modified with rotating disk electrode (RDE) using Sr@La2S3 composite is high, compared to La2S3 and bare electrodes towards the quantitative detection of mesotrione (MTO) in phosphate buffer. Sr@La2S3/RDE showed good sensitivity for MTO detection and it exhibit a range of 0.01-307.01 μM and limit of detection of 2.4 nM. Besides, the selectivity of fabricated electrode is high as it can electrochemically reduce MTO particularly, even in the presence of other chemicals, biological molecules and inorganic ions. The repeatability of MTO detection is high even after 30 days with a lower RSD values. Hence, simple fabrication of Sr@La2S3/RDE could be a novel electrode for the sensitive, selective, and reproducible determination of herbicides in real-time applications.

Glassy Carbon Modified with Cationic Surfactant (GCE/CTAB) as Electrode Material for Fast and Simple Analysis of the Arsenic Drug Roxarsone

For the fast and simple sensing of the arsenic drug roxarsone (ROX), the development of a glassy carbon electrode (GCE) modified with cationic surfactant (cetyltrimethylammonium bromide, CTAB) material is critical. The CTAB-modified glassy carbon electrode, in contrast to the unmodified one, showed excellent behavior for electrochemical reduction of ROX using cyclic voltammetry (CV) and square-wave adsorptive stripping voltammetry (SWAdSV) techniques. CV studies reveal an irreversible reduction process of NO₂ to NH-OH in the ROX molecule in NaAc-HAc buffer (pH = 5.6). The electrode material was characterized using CV and electrochemical impedance spectroscopy. The experiments show that the surfactant-modified material has faster electron transfer and a higher active surface area, and permits a diffusion-adsorption-controlled process. After optimization, the SWAdSV procedure with GCE/CTAB has linear ranges of 0.001-0.02 and 0.02-20 µM, and a detection limit of 0.13 nM. Furthermore, the procedure successfully determined roxarsone in river water samples.

Recent Advances in Nanomaterial-Based Sensing for Food Safety Analysis

The increasing public attention on unceasing food safety incidents prompts the requirements of analytical techniques with high sensitivity, reliability, and reproducibility to timely prevent food safety incidents occurring. Food analysis is critically important for the health of both animals and human beings. Due to their unique physical and chemical properties, nanomaterials provide more opportunities for food quality and safety control. To date, nanomaterials have been widely used in the construction of sensors and biosensors to achieve more accurate, fast, and selective food safety detection. Here, various nanomaterial-based sensors for food analysis are outlined, including optical and electrochemical sensors. The discussion mainly involves the basic sensing principles, current strategies, and novel designs. Additionally, given the trend towards portable devices, various smartphone sensor-based point-of-care (POC) devices for home care testing are discussed.

A Highly Selective and Sensitive Fluorescent Sensor Based on Molecularly Imprinted Polymer-Functionalized Mn-Doped ZnS Quantum Dots for Detection of Roxarsone in Feeds

Roxarsone (ROX) as an organoarsenic feed additive has been widely used in livestock breeding and poultry industry, but ROX can degrade into highly toxic inorganic arsenic species in natural environments to threaten to the environment and human health. Therefore, there is a considerable interest in developing convenient, selective and sensitive methods for the detection of ROX in livestock breeding and poultry industry. In this work, a fluorescent molecularly imprinted polymer (MIPs) probe based on amino-modified Mn-ZnS quantum dots (QDs) has been developed by sol-gel polymerization for specific recognition of ROX. The synthesized MIPs-coated Mn-ZnS QDs (MIPs@Mn-ZnS QDs) have highly selective recognition sites to ROX because there are multi-interactions among the template ROX, functional monomer phenyltrimethoxysilane and the amino-functionalized QDs such as the π-π conjugating effect, hydrogen bonds. Under the optimal conditions, an obvious fluorescence quenching was observed when ROX was added to the solution, and the quenching mechanism could be explained as the photo-induced electron transfer. The MIPs@Mn-ZnS QDs sensor exhibited sensitive response to ROX in the linear range from 3.75 × 10^-8 M to 6.25 × 10^-7 M (R² = 0.9985) and the limit of detection down to 4.34 nM. Moreover, the fluorescence probe has been applied to the quantitative detection of ROX in feed samples, and the recovery was in the range of 91.9% to 108.0%. The work demonstrated that the prepared MIPs@Mn-ZnS QDs probe has a good potential for rapid and sensitive determination of ROX in complicated samples.

Ultrasensitive detection of four organic arsenic compounds at the same time using a five-link cardboard-based assay

In order to effectively control the excessive use of organic arsenic reagents in livestock and poultry products, there is an urgent need to develop a method for rapid detection of multiple organic arsenic reagents. In this study, two haptens were designed and derivatized around the structural formula of roxarsone, and a highly-sensitive group-selective mAb 3F2 was prepared, which can simultaneously detect roxarsone, 4-aminophenylarsonic acid, 2-aminophenylarsonic acid and phenylarsonic acid. We further developed a colloidal gold immunochromatographic test strip (ICS) and prepared a five-link card that can simultaneously detect four organic arsenics in chicken and pork samples. Its quantitative detection limits (LOQ) for the four compounds in chicken and pork samples were 0.06 and 0.32 ng/mL, 0.11 and 0.29 ng/mL, 0.34 and 0.99 ng/mL, and 0.88 and 1.5 ng/mL, respectively. This multi-ICS detection provides a powerful tool for the on-site detection and rapid screening of organic arsenic reagents in actual samples.

Colloidal synthesis of perovskite-type lanthanum aluminate incorporated graphene oxide composites: Electrochemical detection of nitrite in meat extract and drinking water

A novel electrochemical method has been developed for determination of nitrite using La-based perovskite-type lanthanum aluminate nanorod-incorporated graphene oxide nanosheets (LaAlO₃@GO). Morphological and structural analyses of the prepared perovskite-type electrocatalyst, with and without a glassy carbon electrode (GCE) surface, were performed using various techniques, including transmission electron microscopy, energy-dispersive X-ray spectroscopy, X-ray diffractometry, Raman spectroscopy, and electrochemical impedance spectroscopy. Under optimal conditions, the LaAlO₃@GO composite-modified GCE (LaAlO₃@GO/GCE) exhibited excellent electrocatalytic performance toward the electrooxidation of nitrite (pH = 7.0), with a significant increase in anodic peak currents compared with the bare GCE. Using amperometry, the fabricated sensor exhibited a wide nitrite determination range from 0.01 to 1540.5 µM, with a detection limit of 0.0041 µM. Notably, the proposed LaAlO₃@GO/GCE electrode demonstrated a good nitrite detection performance in different meat and water samples. In addition, the LaAlO₃@GO/GCE electrode displayed excellent selectivity, repeatability, reproducibility, storage, and operational stability toward nitrite detection.