Electrochemical sensing of bisphenol A by graphene-1-butyl-3-methylimidazolium hexafluorophosphate modified electrode

2D MXene-Based Nanoscale Materials for Electrochemical Sensing Toward the Detection of Hazardous Pollutants: A Perspective

MXenes (Mn+1XnTx), a subgroup of 2-dimensional (2D) materials, specifically comprise transition metal carbides, nitrides, and carbonitrides. They exhibit exceptional electrocatalytic and photocatalytic properties, making them well-suited for the detection and removal of pollutants from aqueous environments. Because of their high surface area and remarkable properties, they are being utilized in various applications, including catalysis, sensing, and adsorption, to combat pollution and mitigate its adverse effects. Different characterization techniques like XRD, SEM, TEM, UV-Visible spectroscopy, and Raman spectroscopy have been used for the structural elucidation of 2D MXene. Current responses against applied potential were measured during the electrochemical sensing of the hazardous pollutants in an aqueous system using a variety of electroanalytical techniques, including differential pulse voltammetry, amperometry, square wave anodic stripping voltammetry, etc. In this review, a comprehensive discussion on structural patterns, synthesis, properties of MXene and their application for electrochemical detection of lethal pollutants like hydroquionone, phenol, catechol, mercury and lead, etc. are presented. This review will be helpful to critically understand the methods of synthesis and application of MXenes for the removal of environmental pollutants.

An electrochemical sensing platform based on carbon black and chitosan-stabilized platinum nanoparticles

The versatility of chitosan (Ch) biopolymer as a metallic nanoparticle stabilizing agent and excellent former of thin films on glassy carbon was explored in this work for the sustainable manufacture of novel electrochemical sensors based on carbon black (CB) and chitosan-stabilized platinum nanoparticles (Ch-PtNPs). Platinum nanoparticles highly stabilized by chitosan were easily synthesized at room temperature and characterized by HR-TEM, UV-vis, and voltammetry. Ch-PtNPs presented an average diameter of 2.7 nm, and typical voltammetric peaks of Pt in sulfuric acid medium were detected for films containing Ch-PtNPs. As a proof of concept, the CB-Ch-PtNP electrode was applied in the determination of hydrogen peroxide (H₂O₂) and the endocrine disruptor bisphenol A (BPA). Pronounced electrocatalytic activity towards H₂O₂ reduction was observed in the presence of Ch-PtNPs in the films, guaranteeing the non-enzymatic determination of H₂O₂ by chronoamperometry, with a limit of detection of 10 μmol L^-1. In the determination of BPA by differential pulse adsorptive anodic stripping voltammetry (DPAdASV), under optimal experimental conditions, a wide linear response range and a limit of detection at the nanomolar level (7.9 nmol L^-1) were achieved. In addition, excellent repeatabilities of sensor response and sensor fabrication, and accuracy in the analysis of natural water samples were obtained.

Properties and Recent Advantages of N,N’-dialkylimidazolium-ion Liquids Application in Electrochemistry

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N,Nʹ-dialkylimidazolium-ion liquids is one of the important ionic liquids with a wide range of application as conductive electrolyte and in electrochemistry. The modified electrodes create a new view in fabrication of electroanalytical sensors. Many modifiers have beeen suggested for modification of electroanalytical sensor since many years ago. Over these years, ionic liquids and especially room temperature ionic liquids have attracted more attention due to their wide range of electrochemical windows and high electrical conductivity. N,Nʹ-dialkylimidazolium-ion liquids are one of the main important ionic liquids suggested for modification of bare electrodes and especially carbon paste electrodes. Although many review articles have reported onthe use of ionic liquids in electrochemical sensors, no review article has been specifically introduced so far on the review of the advantages of N,Nʹ-dialkylimidazolium ionic liquid. Therefore, in this review paper we focused on the introduction of recent advantages of N,Nʹ-dialkyl imidazolium ionic liquid in electrochemistry.

Triple-signaling amplification strategy based electrochemical sensor design: boosting synergistic catalysis in metal-metalloporphyrin-covalent organic frameworks for sensitive bisphenol A detection

A covalent organic framework (COF) is a promising type of porous material with customizable surface characteristics. Confining multiple catalytic units within a mesoporous COF can generate abundant active sites and improve the catalytic performance. In this work, a COF with both metalloporphyrin and a metal nanoparticle complex denoted as hemin/TAPB-DMTP-COF/AuNPs (TAPB: 1,3,5-tris(4-amino-phenyl)benzene, DMTP: 2,5-dimethoxyterephaldehyde, AuNPs: Au nanoparticles) has been successfully fabricated through a hierarchical encapsulation method. The as-synthesized composite was then employed to construct an electrochemical sensing platform for the efficient detection of bisphenol A (BPA). Under the optimal conditions, the hemin/TAPB-DMTP-COF/AuNP sensor presented a linear range of 0.01-3 μmol L^-1 and a low detection limit of 3.5 nmol L^-1. The satisfactory signal amplification is based on a triple-signaling amplification strategy due to the abundant Fe³⁺ sites of Fe-porphyrin, high conductivity of AuNPs and a large specific surface area of the TAPB-DMTP-COF. The proposed method was used to measure the content of BPA in different water samples with a satisfactory recovery from 95.5 to 104.0%, suggesting the great potential of the sensor in practical applications.

An Electrochemical Sensor Based on Gold Nanodendrite/Surfactant Modified Electrode for Bisphenol A Detection

In the present work, we reported the simple way to fabricate an electrochemical sensing platform to detect Bisphenol A (BPA) using galvanostatic deposition of Au on a glassy carbon electrode covered by cetyltrimethylammonium bromide (CTAB). This material (CTAB) enhances the sensitivity of electrochemical sensors with respect to the detection of BPA. The electrochemical response of the modified GCE to BPA was investigated by cyclic voltammetry and differential pulse voltammetry. The results displayed a low detection limit (22 nm) and a linear range from 0.025 to 10 µm along side with high reproducibility (RSD = 4.9% for seven independent sensors). Importantly, the prepared sensors were selective enough against interferences with other pollutants in the same electrochemical window. Notably, the presented sensors have already proven their ability in detecting BPA in real plastic water drinking bottle samples with high accuracy (recovery range = 96.60%-102.82%) and it is in good agreement with fluorescence measurements.

Performance of chitosan polymer as platform during sensors fabrication and sensing applications

Chitosan is an important polymer produced from deacetylation of several sea and insects crusts. Due to its environmental fate and biological biocompatibility, it can be used in several biological and environmental applications. Sensing of biological compounds in human bodies and also in serum, blood, and different body fluids has found an important application instead of direct determination of the body fluids using complicated tools. Sensing process of biological compounds during bio-analysis of the biological systems, especially human fluids lack of several parameters including: high sensitivity, repeatability, speed of analysis and biocompatibility of the used analytical methods, especially in-vivo analysis. That was due to the time between sample handling and sample determination can change various components and concentrations of the bio-compounds. The need for in-situ analysis was directed the researchers for biosensors to overcome the upgrading problems of bio-analysis. Biosensors were the future of this issue. Chitosan can reserve as great platform for fabrication of different sensors to determine the elements, compounds and body bioactive compounds. The presence of different terminal amino and hydroxyl groups within chitosan framework facilitates the immobilization of different biomarkers to be used as sensing elements for the determined compounds. The use of chitosan as sensors platform was enhanced by using chitosan in its nanoforms.

Recent Trends in the Analysis of Chemical Contaminants in Beverages

Chemical contaminants should not be present in beverages for human consumption, but could eventually be ingested by consumers as they may appear naturally from the environment or be produced by anthropogenic sources. These contaminants could belong to many different chemical sources, including heavy metals, amines, bisphenols, phthalates, pesticides, perfluorinated compounds, inks, ethyl carbamate, and others. It is well known that these hazardous chemicals in beverages can represent a severe threat by the potential risk of generating diseases to humans if no strict quality control is applied during beverages processing. This review compiles the most updated knowledge of the presence of potential contaminants in various types of beverages (both alcoholic and non-alcoholic), as well as in their containers, to prevent undesired migration. Special attention is given to the extraction and pre-concentration techniques applied to these samples, as well as to the analytical techniques necessary for the determination of chemicals with a potential contaminant effect. Finally, an overview of the current legislation is carried out, as well as future trends of research in this field.

Simplistic one-pot synthesis of an inorganic–organic cubic caged material: a new interface for detecting toxic bisphenol-A electrochemically

Polyhedral oligomeric silsesquioxane (POSS) based hybrid nanomaterials have been terminally functionalised with three different functional groups and are newly explored for the electrochemical sensing of bisphenol A.

Aptamer based electrochemiluminescent determination of bisphenol A by using carboxylated graphitic carbon nitride

An electrochemiluminescence (ECL) based assay is described for the determination of the endocrine disruptor bisphenol A (BPA). The method is based on the use of carboxylated graphitic carbon nitride (C-g-C₃N₄) carrying an immobilized aptamer against BPA. In the presence of BPA, the ECL signal decreases due to ECL energy transfer from excited-state C-g-C₃N₄ to the BPA oxidation product. Under the optimal conditions, ECL intensity increases linearly in the 0.1 pM to 1 nM BPA concentration range. The detection limit is as low as 30 fM. The assay has excellent sensitivity, outstanding stability and high selectivity. It was applied to the determination of BPA in spiked water samples. Graphical abstract Aptamer modified carboxylated graphitic carbon nitride was synthesized and applied in an electrochemiluminescence-based aptasensor for bisphenol A.

Rational functionalization of reduced graphene oxide with an imidazole group for the electrochemical sensing of bisphenol A - an endocrine disruptor

Reduced graphene oxide has been rationally functionalized with histamine for the highly sensitive and selective electrochemical determination of bisphenol A (BPA). Histamine is covalently attached to graphene oxide by amide coupling and the oxygen functionalities of graphene oxide are partially reduced electrochemically. The facilitated electrochemical oxidation of BPA was achieved in neutral pH with functionalized reduced graphene oxide. The pH of the reaction controls the oxidation of BPA. Electrochemical oxidation is not favourable at pH less than the pKa of histamine due to the protonation of the imidazole nitrogen. The electrode is highly sensitive (1727.29 ± 12.48 nA μM-1 cm-2) towards BPA and shows a linear response up to 30 μM of BPA. It could detect as low as 0.03 nM of BPA (S/N = 5). The other coexisting analytes do not interfere with the voltammetric measurement of BPA.

Ionic liquid-functionalized graphene quantum dot-bonded silica as multi-mode HPLC stationary phase with enhanced selectivity for acid compounds

A novel IL/GQD/SiO₂ stationary phase for reversed-phase/normal-phase/ionic exchange and hydrophilic interaction liquid chromatography.

Highly sensitive aptamer based on electrochemiluminescence biosensor for label-free detection of bisphenol A

Bisphenol A (BPA), a typical endocrine disruptor, is widely used as a key monomer in the packaging industry. Residual monomer can transfer from the package material to the food and thereby pose a risk to the health of the consumer, so determination of BPA migration is highly important for food safety control. In this study, a simple but sensitive electrochemiluminescence (ECL) biosensor, which combines the characteristics of high selectivity of an aptamer and high sensitivity of ECL, has been developed to detect BPA from package materials. The aptamer was immobilized on a gold electrode surface through Au-S interaction. The aptamer was then hybridized with complementary DNA (CDNA) to form double-stranded DNA (dsDNA). Ru(phen)₃²⁺ can intercalate into the grooves of dsDNA and acts as an ECL indicator; high ECL intensity can therefore be detected from the electrode surface. In the presence of BPA, which can competitively bind with the aptamer owing to their high affinity, Ru(phen)₃²⁺ is released from the electrode surface and the ECL of the system is decreased. The decreasing ECL signal has a linear relationship with BPA in the range of 0.1-100 pM with a detection limit of 0.076 pM. The developed biosensor has been applied to detect migration of BPA from different categories of canned drink with satisfactory results.

Advances in sensing and biosensing of bisphenols: A review

Bisphenols (BPs) are well known endocrine disrupting chemicals (EDCs) that cause adverse effects on the environment, biotic life and human health. BPs have been studied extensively because of an increasing concern for the safety of the environment and for human health. They are major raw materials for manufacturing polycarbonates, thermal papers and epoxy resins and are considered hazardous environmental contaminants. A vast array of sensors and biosensors have been developed for the sensitive screening of BPs based on carbon nanomaterials (carbon nanotubes, fullerenes, graphene and graphene oxide), quantum dots, metal and metal oxide nanocomposites, polymer nanocomposites, metal organic frameworks, ionic liquids and molecularly imprinted polymers. This review is devoted mainly to a variety of sensitive, selective and reliable sensing and biosensing methods for the detection of BPs using electrochemistry, fluorescence, colorimetry, surface plasmon resonance, luminescence, ELISAs, circular dichroism, resonance Rayleigh scattering and adsorption techniques in plastic products, food samples, food packaging, industrial wastes, pharmaceutical products, human body fluids and many other matrices. It summarizes the advances in sensing and biosensing methods for the detection of BPs since 2010. Furthermore, the article discusses challenges and future perspectives in the development of novel sensing methods for the detection of BP analogs.

In vitro and in silico assessment of the structure-dependent binding of bisphenol analogues to glucocorticoid receptor

Widespread use of bisphenol A (BPA) and other bisphenol analogues has attracted increasing attention for their potential adverse effects. As environmental endocrine-disrupting compounds (EDCs), bisphenols (BPs) may activate a variety of nuclear receptors, including glucocorticoid receptor (GR). In this work, the binding of 11 BPs to GR was investigated by fluorescence polarization (FP) assay in combination with molecular dynamics simulations. The human glucocorticoid receptor was prepared as a soluble recombinant protein. A fluorescein-labeled dexamethasone derivative (Dex-fl) was employed as tracer. Competitive displacement of Dex-fl from GR by BPs showed that the binding affinities of bisphenol analogues were largely dependent on their characteristic functional groups. In order to further understand the relationship between BPs structures and their GR-mediated activities, molecular docking was utilized to explore the binding modes at the atomic level. The results confirmed that structural variations of bisphenol analogues contributed to different interactions of BPs with GR, potentially causing distinct toxic effects. Comparison of the calculated binding energies vs. experimental binding affinities yielded a good correlation (R ² = 0.8266), which might be helpful for the design of environmentally benign materials with reduced toxicities. In addition, the established FP assay based on GR exhibited the potential to offer an alternative to traditional methods for the detection of bisphenols.

ZrO2 supported Nano-ZSM-5 nanocomposite material for the nanomolar electrochemical detection of metol and bisphenol A

ZrO₂ decorated Nano-ZSM-5 was synthesized by the calcination of the physical mixture of ZrO₂ and Nano-ZSM-5. Electrochemical sensor based on this material was investigated in the determination of hazardous organic water pollutants.

A novel electrochemical aptasensor for bisphenol A assay based on triple-signaling strategy

Based on a triple-signaling strategy, a novel electrochemical aptasensor has been developed for sensitive and selective detection of bisphenol A (BPA). The thiolated ferrocene (Fc)-modified BPA-binding aptamer probe (Fc-P) was immobilized on the gold electrode and then hybridized with the methylene blue (MB)-modified complementary DNA probe (MB-P) to form a rigid double-stranded DNA (ds-DNA). The specific interaction between BPA and Fc-P led to the release of MB-P from the sensing interface and the conformational change of Fc-P. As a result, the oxidation peak currents of Fc and BPA increased with the increase of the concentration of target (BPA) according to the "signal-on" mode while that of MB decreased with the increase of the BPA concentration according to the "signal-off" mode. By superimposing the triple signal changes, BPA was detected sensitively with a linear range from 1 pM to 100 pM. The detection limit is 0.19 pM, and much lower than that obtained by most of the reported electrochemical methods. The aptasensor also exhibited satisfactory specificity, selectivity, reproducibility and stability. By changing the specific aptamers, this strategy could be easily extended to detect other redox targets, showing promising applications in environmental analysis, food safety monitoring, and bioanalysis.

Electrochemical determination of bisphenol A at ordered mesoporous carbon modified nano-carbon ionic liquid paste electrode

A simple bisphenol A (BPA) sensor was successfully fabricated based on ordered mesoporous carbon CMK-3 modified nano-carbon ionic liquid paste electrode (CMK-3/nano-CILPE). The nanostructure of CMK-3 and the surface morphologies of modified electrodes were characterized by transmission electron microscopy (TEM) and scanning electron microscopy (SEM). Electrochemical properties of the fabricated electrodes were investigated by cyclic voltammetry (CV) and electrochemical impedance spectroscopy (EIS). The fabricated sensor displayed excellent electroactivity towards bisphenol A using linear sweep voltammetry (LSV). Experimental conditions influencing the analytical performance of the modified electrode were optimized. Under optimal conditions, the oxidation peak current was proportional to BPA concentration in the range from 0.2 μM to 150 μM with a detection limit of 0.05 μM (S/N=3). This method was successfully used for determination of BPA leached from drinking bottle and plastic bag with good recoveries.

Molecularly imprinted electrochemical sensor based on an electrode modified with an imprinted pyrrole film immobilized on a β-cyclodextrin/gold nanoparticles/graphene layer

A novel molecularly imprinted electrochemical sensor was constructed for the sensitive detection of quercetin (Qu) based on a glassy carbon electrode (GCE) modified with β-cyclodextrin (β-CD), gold nanoparticles(AuNPs) and graphene (GR).