Nanomaterials modified electrodes for electrochemical detection of Sudan I in food

Recent advances in electrochemical detection of common azo dyes

PURPOSE

Food forensics is an emerging field and the initial part of this review showcases the toxic effects and the instrumental methods applied for the detection of the most commonly used azo dyes. Electrochemical detection has a lot of advantages and hence the significance of the most important techniques used in the electrochemical detection is discussed. The major part of this review highlights the surface modified electrodes, utilized for the detection of the most important azo dyes to achieve low detection limit (LOD).

METHODS

A thorough literature study was conducted using scopus, science direct and other scientific databases using specific keywords such as toxic azo dyes, electrochemical detection, modified electrodes, LOD etc. The recent references in this field have been included.

RESULTS

From the published literature, it is observed that with the growing interests in the field of electrochemical techniques, a lot of importance have been given in the area of modifying the working electrodes. The results unambiguously show that the modified electrodes outperform bare electrodes and offer a lower LOD value.

CONCLUSION

According to the literature reports it can be concluded that, compared to other detection methods, electrochemical techniques are much dependable and reproducible. The fabrication of the electrode material with the appropriate modifications is the main factor that influences the sensitivity. Electrochemical sensors can be designed to be more sensitive, more reliable, and less expensive. These sensors can be effectively used by toxicologists to detect trace amounts of harmful dyes in food samples.

Aptamer-modified paper-based analytical devices for the detection of food hazards: Emerging applications and future perspective

Food analysis plays a critical role in assessing human health risks and monitoring food quality and safety. Currently, there is a pressing need for a reliable, portable, and quick recognition element for point-of-care testing (POCT) to better serve the demands of on-site food analysis. Aptamer-modified paper-based analytical devices (Apt-PADs) have excellent characteristics of high portability, high sensitivity, high specificity, and on-site detection, which have been widely used and concerned in the field of food safety. The article reviews the basic components and working principles of Apt-PADs, and introduces their representative applications detecting food hazards. Finally, the advantages, challenges, and future directions of Apt-PADs-based sensing performance are discussed, to provide new directions and insights for researchers to select appropriate Apt-PADs according to specific applications.

An amplified electrochemical sensor employing one-step synthesized nickel-copper-zinc ferrite/carboxymethyl cellulose/graphene oxide nanosheets composite for sensitive analysis of omeprazole

In this work, a signal amplification strategy was designed by the fabrication of a highly sensitive and selective electrochemical sensor based on nickel-copper-zinc ferrite (Ni0.4Cu0.2Zn0.4Fe2O4)/carboxymethyl cellulose (CMC)/graphene oxide nanosheets (GONs) composite modified glassy carbon electrode (GCE) for determination of omeprazole (OMP). The one-step synthesized Ni0.4Cu0.2Zn0.4Fe2O4/CMC/GONs nanocomposite was characterized by scanning electron microscopy, energy-dispersive X-ray spectroscopy, transmission electron microscopy and X-ray diffraction techniques. Then, the Ni0.4Cu0.2Zn0.4Fe2O4/CMC/GONs/GCE was applied to study the electrochemical behavior of the OMP. Electrochemical data show that the Ni0.4Cu0.2Zn0.4Fe2O4/CMC/GONs/GCE exhibits superior electrocatalytic performance on the oxidation of OMP compared with bare GCE, GONs/GCE, CMC/GONs/GCE and MFe2O4/GCE (M = Cu, Ni and Zn including single, double and triple of metals) which can be attributed to the synergistic effects of the nanocomposite components, outstanding electrical properties of Ni0.4Cu0.2Zn0.4Fe2O4 and high conductivity of CMC/GONs as well as the further electron transport action of the nanocomposite. Under optimal conditions, the Ni0.4Cu0.2Zn0.4Fe2O4/CMC/GONs/GCE offers a high performance toward the electrodetermination of OMP with the wide linear-range responses (0.24-5 and 5-75 μM), lower detection limit (0.22 ± 0.05 μM), high sensitivity (1.1543 μA μM-1 cm-2), long-term signal stability and reproducibility (RSD = 2.54%). It should be noted that the Ni0.4Cu0.2Zn0.4Fe2O4/CMC/GONs/GCE sensor could also be used for determination of OMP in drug and biological samples, indicating its feasibility for real analysis.

An innovative nanoparticle-modified carbon paste sensor for ultrasensitive detection of lignocaine and its extremely carcinogenic metabolite residues in bovine food samples: Application of NEMI, ESA, AGREE, ComplexGAPI, and RGB12 algorithms

Nowadays, veterinary medicine residues have been viewed as a major threat to food safety worldwide, especially when dealing with carcinogenic residues. Herein, we present the first differential pulse voltammetric method for the quantification of lignocaine and its carcinogenic metabolite 2,6-xylidine residues in bovine food samples, aided by five greenness and whiteness assessment tools, including NEMI, ESA, ComplexGAPI, AGREE, and RGB12. The method depends on the electrochemical oxidation after modification of the carbon paste sensor with recycled Al₂O₃-NPs functionalized multi-walled carbon nanoparticles. The produced sensor (Al₂O₃-NPs/MWCNTs/CPE) was characterized using XRD, FT-IR, EDX, SEM, and TEM. As expected, the active surface area and electron transfer processes were accelerated by the modification, resulting in ultra-sensitive quantification with detection limits of 19.00 and 13.94 nM for lignocaine and 2,6-xylidine, respectively. In terms of greenness, whiteness, sustainability, analytical effectiveness, and economic and practical considerations, the proposed method outperforms the reported methods.

Sensing of azo toxic dyes using nanomaterials and its health effects - A review

Development of science has taken over our lives and made it mandatory to live with science. Synthetic technology takes more than it has given for our welfare. In the process of meeting the demand of the consumers, industries supported synthetic products to meet the same. One such sector that employs synthetic azo dyes for food coloring is the food industry. The result of the process is the production of a variety of colored foods which looks more appealing and palatable. The process not only meets the consumer's demand it also has an impact on customers' health because the consumption of azo-toxic dye-treated foods regularly or in direct contact with synthetic azo dyes can also cause severe human health consequences. Nanotechnology is a rapidly evolving branch of research in which nanosensors are being developed for a variety of applications, including sensing various azo-toxic dyes in food products, which provides a wider scope in the future, with the innovation in designing different nanosensors. The current review focuses on the different types of nanosensors, their key role in sensing, and the sensing of azo toxic dyes using nanosensors, their advantages over other sensors, applications of nanomaterials, and the health impacts of azo dyes on humans, appropriate parameters for maximum permissible limits, and an Acceptable Daily Intake (ADI) of azo toxic dye to be followed. The regulations followed on the application of colorants to the food are also elaborated. The review also focuses on the application of enzyme-based biosensors in detecting azo dyes in food products.

A New Electrochemical Sensor for the Detection of Ketoconazole Using Carbon Paste Electrode Modified with Sheaf-like Ce-BTC MOF Nanostructure and Ionic Liquid

An ultrasensitive and selective voltammetric sensor with an ultratrace-level detection limit is introduced for ketoconazole (KTC) determination in real samples using a modified carbon paste electrode with a sheaf-like Ce-BTC MOF nanostructure and ionic liquid. The as-synthesized nanostructure was characterized by several techniques, including energy-dispersive X-ray spectroscopy (EDX), X-ray diffraction (XRD), and field emission scanning electron microscopy (FE-SEM). The electrocatalytic performance of the developed electrode was observed by cyclic voltammetry (CV), differential pulse voltammetry (DPV), linear sweep voltammetry (LSV), and chronoamperometry. The limit of detection (LOD) of the developed sensor for KTC is 0.04 μM, and the response was found to be in the dynamic concentration range of 0.1-110.0 μM in a phosphate buffer solution. The proposed electrode exhibits acceptable electrocatalytic activity for KTC oxidation with a high sensitivity of 0.1342 μA·μM^-1. The ability of the fabricated sensor to monitor KTC in real aqueous samples is demonstrated using standard addition data.

Electrochemical sensor amplified with cellulose nanofibers/Fe3O4 composite to the monitoring of hydrazine as a pollutant in water and wastewater samples

A quite swift and sensitive analytical instrument was designed in this work to detect and monitor hydrazine in various water and wastewater samples. The glassy carbon electrode (GCE) was amplified using cellulose nanofibers/Fe₃O₄ composite (CNF-Fe₃O₄/NC) for monitoring hydrazine in the concentration range of 0.001 - 140 M with a superior detection limit of 0.5 nM. Results showed a diffusion control process for the oxidation of hydrazine at the surface of CNF-Fe₃O₄/NC/GCE. Under the optimum condition (pH=8.0), the oxidation current of hydrazine was improved by about 2.3 times and the oxidation potential was reduced by about 60 mV at the surface of CNF-Fe₃O₄/NC/GCE compare to unmodified GCE. A standard addition method was employed to assess CNF-Fe₃O₄/NC/GCE's capability for the detection of hydrazine in water and wastewater samples, and a recovery range of 97.6 % to 104.9 % was noted.

A recent advancement on the applications of nanomaterials in electrochemical sensors and biosensors

Industrialization and globalization, both on an international and local scale, have caused large quantities of toxic chemicals to be released into the environment. Thus, developing an environmental pollutant sensor platform that is sensitive, reliable, and cost-effective is extremely important. In current years, considerable progress has been made in the expansion of electrochemical sensors and biosensors to monitor the environment using nanomaterials. A large number of emerging biomarkers are currently in existence in the biological fluids, clinical, pharmaceutical and bionanomaterial-based electrochemical biosensor platforms have drawn much attention. Electrochemical systems have been used to detect biomarkers rapidly, sensitively, and selectively using biomaterials such as biopolymers, nucleic acids, proteins etc. In this current review, several recent trends have been identified in the growth of electrochemical sensor platforms using nanotechnology such as carbon nanomaterials, metal oxide nanomaterials, metal nanoparticles, biomaterials and polymers. The integration strategies, applications, specific properties and future projections of nanostructured materials for emerging progressive sensor platforms are also observed. The objective of this review is to provide a comprehensive overview of nanoparticles in the field of electrochemical sensors and biosensors.

Sudan I monitoring as a hazardous azo dye using an electroanalytical tool amplified with NiO/SWCNTs-ionic liquid catalysts

Sudan I is an azo dye that causes cancer and is not allowed to be used in food products. The current study focused on the design and manufacture of an electrochemical sensor modified with NiO/SWCNTs, as a nano-catalyst, and 1-hexyl-3-methylimidazolium bis(trifluoromethylsulfonyl)imide (1H3MIbTMI), as an ionic liquid binder, to monitor Sudan I as azo additive dyes in various food samples. The modified carbon paste electrode (CPE/NiO/SWCNTs/1H3MIbTMI) offered superior electrochemical performance metrics as an analytical sensor to detect trace levels of Sudan I within the concentration range of 1.0 nM-250 μM. The limit of detection was determined as 0.3 nM by the differential pulse voltammetric (DPV) technique. The proposed CPE/NiO/SWCNTs/1H3MIbTMI can be put forward to be employed as an analytical instrument for sensing Sudan I in various culinary sauces, including chili, tomato, and strawberry sauces. The obtained recovery range was determined as 97.6%-104.35%. These findings demonstrated the effectiveness of the newly created material and its potential for usage as a novel analytical instrument.

Tungsten Disulfide Decorated Screen-Printed Electrodes for Sensing of Glycated Hemoglobin

Diabetes is a global menace, and its severity results in various disorders including cardiovascular, retinopathy, neuropathy, and nephropathy. Recently, diabetic conditions are diagnosed through the level of glycated hemoglobin. The level of glycated hemoglobin is determined with enzymatic methodology. Although the system is sensitive, it has various restrictions such as long processing times, expensive equipment required for testing, and complex steps involved in sample preparation. These limitations are a hindrance to faster results. The limitations of the developed methods can be eliminated through biosensors. In this work, an electrochemical platform was fabricated that facilitates the identification of glycated hemoglobin protein in diabetic patients. The working electrode on the integrated circuit was modified with molecularly imprinted polymer decorated with tungsten disulfide nanoparticles to enhance its analytical properties. The analytical properties of the biosensor were studied using electrochemical techniques. The obtained detection limit of the nanoelectronic sensor was 0.01 pM. The calculated sensitivity of the biosensor was observed to be 0.27 μA/pM. Also, the sensor promises to operate in a dynamic working concentration range and provide instant results.

Polyoxometalates-graphene nanocomposites modified electrode for electro-sensing detection of Sudan I in food

Sudan I, a lipophilic azo dye -dye, is desirable and urgent to be accurate detected due to its increasing levels and high toxicity in food and environmental monitoring and analysis. Herein, a sensitive electrochemical sensor for Sudan I was established based on a new K₁₀P₂W₁₈Fe₄(H₂O)₂O₆₈ functionalized carbon nanomaterials (Fe₄P₂W₁₈-GNPS). The electrode modified nanocomposite, Fe₄P₂W₁₈-GNPS, was successfully fabricated and characterized by FTIR, SEM and UV-vis. The effective combination of Fe₄P₂W₁₈ and graphene exhibited high electrocatalytic activity towards the oxidation of Sudan I, promote charge transfer, and more sensing sites. Under optimized experimental conditions, the proposed differential pulse voltammetry (DPV) showed excellent analytical performances for Sudan I with the limit of detection (LOD) of 5 nM (S/N = 3), the sensitivity of 13.10 μA·μM^-1cm^-2 at the 0.005-2 μM and 0.39 μA·μM^-1cm^-2 at 10-200 μM. The stability and reproducibility make the electrochemical sensor suitable for detecting the Sudan I in food.

Towards Development of Molecularly Imprinted Electrochemical Sensors for Food and Drug Safety: Progress and Trends

Due to their advantages of good flexibility, low cost, simple operations, and small equipment size, electrochemical sensors have been commonly employed in food safety. However, when they are applied to detect various food or drug samples, their stability and specificity can be greatly influenced by the complex matrix. By combining electrochemical sensors with molecular imprinting techniques (MIT), they will be endowed with new functions of specific recognition and separation, which make them powerful tools in analytical fields. MIT-based electrochemical sensors (MIECs) require preparing or modifying molecularly imprinted polymers (MIPs) on the electrode surface. In this review, we explored different MIECs regarding the design, working principle and functions. Additionally, the applications of MIECs in food and drug safety were discussed, as well as the challenges and prospects for developing new electrochemical methods. The strengths and weaknesses of MIECs including low stability and electrode fouling are discussed to indicate the research direction for future electrochemical sensors.

Utilization of a double-cross-linked amino-functionalized three-dimensional graphene networks as a monolithic adsorbent for methyl orange removal: Equilibrium, kinetics, thermodynamics and artificial neural network modeling

Herein, it is aimed to develop a high-performance monolithic adsorbent to be utilized in methyl orange (MO) adsorption. Therefore, amino-functionalized three-dimensional graphene networks (3D-GN_f) fulfilling the requirements of reusability and high capacity have been fabricated via hydrothermal self-assembly approach followed by a double-crosslinking strategy. The potential utilization of 3D-GN_f as an adsorbent for removal MO has been assessed using both batch-adsorption studies and an artificial neural network (ANN) approach. Graphene oxide sheets have been amino-functionalized and cross-linked, by ethylenediamine (EDA) during hydrothermal treatment, following the glutaraldehyde has used as a double-crosslinking agent to facilitate the crosslinking of architecture. The successful fabrication of 3D-GN_f has been confirmed by field-emission scanning electron microscopy (FESEM), Fourier transform infrared (FT-IR), Raman and X-ray photoelectron spectroscopy (XPS). Moreover, N₂ adsorption/desorption isotherms have revealed the high specific surface area (1015 m² g^-1) with high pore volume (1.054 cm³ g^-1) and hierarchical porous structure of 3D-GN_f. The effect of initial concentration, contact time, and temperature on adsorption capacity have been thoroughly studied, and the kinetics, isotherms, and thermodynamics of MO adsorption have been modelled. The MO adsorption has been well defined by the pseudo-second-order kinetic model and Langmuir isotherm model with a monolayer adsorption capacity of 270.27 mg g^-1 at 25 °C. The thermodynamic findings have revealed MO adsorption has occurred spontaneously with an endothermic process. The Levenberg-Marquardt backpropagation algorithm has been implemented to train the ANN model, which has used the activation functions of tansig and purelin functions at the hidden and output layers, respectively. An optimum ANN model with high-performance metrics (coefficient of determination, R² = 0.9995; mean squared error, MSE = 0.0008) composed of three hidden layers with 5 neurons in each layer was constructed to forecast MO adsorption. The findings have shown that experimental results are consistent with ANN-based data, implying that the suggested ANN model may be used to forecast cationic dye adsorption.

Advancement in electrochemical strategies for quantification of Brown HT and Carmoisine (Acid Red 14) Drom Azo Dyestuff class

Brown HT and carmoisine, which are the most used dyestuffs in pharmaceuticals, textiles, cosmetics and foods, are important components of the Azo family. Although the Azo group is not toxic or carcinogenic under normal conditions, these dyestuffs require great care due to the reduction of the Azo functional group to amines. In particular, fast, reliable, easy, on-site and precise determinations of these substances are extremely necessary and important. In this review, the properties, applications, and electrochemical determinations of brown HT and carmoisine, which are used as synthetic food colorants, are discussed in detail. Up to now, sensor types, detection limits (LOD and LOQ), and analytical applications in the developed electrochemical strategies for both substances were compared. In addition, the validation parameters such as the variety of the sensors, sensitivity, selectivity and electrochemical technique in these studies were clarified one by one. While the electrochemical techniques recommended for brown HT were mostly used for the removal of dyestuff, for carmoisine they included fully quantitative centered studies. The percentiles of voltammetric techniques, which are the most widely used among these electroanalytical methods, were determined. The benefits of a robust electrochemical strategy for the determination of both food colors are summed up in this review. Finally, the brown HT and carmoisine suggestions for future perspectives in electrochemical strategy are given according to all their applications.

Identification of heavy metal ions from aqueous environment through gold, Silver and Copper Nanoparticles: An excellent colorimetric approach

Heavy metal pollution has become a severe threat to human health and the environment for many years. Their extensive release can severely damage the environment and promote the generation of many harmful diseases of public health concerns. These toxic heavy metals can cause many health problems such as brain damage, kidney failure, immune system disorder, muscle weakness, paralysis of the limbs, cardio complaint, nervous system. For many years, researchers focus on developing specific reliable analytical methods for the determination of heavy metal ions and preventing their acute toxicity to a significant extent. The modern researchers intended to utilize efficient and discerning materials, e.g. nanomaterials, especially the metal nanoparticles to detect heavy metal ions from different real sources rapidly. The metal nanoparticles have been broadly utilized as a sensing material for the colorimetric detection of toxic metal ions. The metal nanoparticles such as Gold (Au), Silver (Ag), and Copper (Cu) exhibited localized plasmon surface resonance (LPSR) properties which adds an outstanding contribution to the colorimetric sensing field. Though, the stability of metal nanoparticles was major issue to be exploited colorimetric sensing of heavy emtal ions, but from last decade different capping and stabilizing agents such as amino acids, vitmains, acids and ploymers were used to functionalize the metal surface of metal nanoparticles. These capping agents prevent the agglomeration of nanoparticles and make them more active for prolong period of time. This review covers a comprehensive work carried out for colorimetric detection of heavy metals based on metal nanoparticles from the year 2014 to onwards.

In situ vertical alignment of 2D MoS2 layers on GO film: enhanced electrochemical properties for PD-L1 sensing

There is an urgent need for a flexible and simple programmed cell death ligand 1 (PD-L1) dynamic measurement method enabling real-time monitoring of cancer progression and assessment of immunotherapy efficacy. In the current study, we show facile in situ synthesis of vertical alignment two-dimensional molybdenum disulfide (2D MoS₂) layers on graphene-oxide-modified ITO (MoS_2┴GO-ITO) using a hydrothermal approach and demonstrate the importance of the alignment of 2D in achieving high-probe capturing, enhanced electrochemical properties and target selectivity during sensing. After modification of designed PD-L1 binding peptides on the MoS_2┴GO-ITO, a sensitive PD-L1 electrochemical sensor was designed using vertical alignment MoS₂ to capture more probes for PD-L1 recognition and excellent in plane electron transport to accelerate electrochemical signals. The fabricated electrochemical sensor could sensitively determine PD-L1 in a wide linear range of 25-500 ng/mL and exhibit desirable accuracy and reliability in clinical samples application. This simple and sensitive method is likely to investigate further research into the exploration of the perpendicular alignment of 2D surfaces for diverse applications.

Monitoring of atropine anticholinergic drug using voltammetric sensor amplified with NiO@Pt/SWCNTs and ionic liquid

In this work, the synergic impact of 1-ethyl-3-methylimidazolium methyl sulfate (EMMS) and NiO doped Pt decorated SWCNTs (NiO@Pt/SWCNTs) in carbon paste matrix was examined as an analytical tool for investigating electrochemical behavior of atropine. The voltammetric results revealed that NiO@Pt/SWCNTs/EMMS/CPE exhibited an excellent electrocatalytic activity towards redox reaction of atropine in aqueous solution pH = 10.0. The NiO@Pt/SWCNTs/EMMS/CPE offered the best electro-analytical conditions for monitoring of atropine in the concentration range of 4.0 nM-220 μM with an increase in oxidation current about 5.93 times. On the other hand, NiO@Pt/SWCNTs/EMMS/CPE displayed a long time stability (about 60 days) for monitoring of atropine. The ability of NiO@Pt/SWCNTs/EMMS/CPE as an electroanalytical tool for monitoring of atropine was investigated, and the recovery range was detected as to be 97.6%-104.25% for this goal.