Multiwalled carbon nanotubes/gold nanocomposites-based electrochemiluminescent sensor for sensitive determination of bisphenol A

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.

A state-of-art-review on emerging contaminants: Environmental chemistry, health effect, and modern treatment methods

Pollution problems are increasingly becoming e a priority issue from both scientific and technological points of view. The dispersion and frequency of pollutants in the environment are on the rise, leading to the emergence have been increasing, including of a new class of contaminants that not only impact the environment but also pose risks to people's health. Therefore, developing new methods for identifying and quantifying these pollutants classified as emerging contaminants is imperative. These methods enable regulatory actions that effectively minimize their adverse effects to take steps to regulate and reduce their impact. On the other hand, these new contaminants represent a challenge for current technologies to be adapted to control and remove emerging contaminants and involve innovative, eco-friendly, and sustainable remediation technologies. There is a vast amount of information collected in this review on emerging pollutants, comparing the identification and quantification methods, the technologies applied for their control and remediation, and the policies and regulations necessary for their operation and application. In addition, This review will deal with different aspects of emerging contaminants, their origin, nature, detection, and treatment concerning water and wastewater.

A molecularly imprinted polypyrrole electrochemiluminescence sensor based on a novel zinc-based metal-organic framework and chitosan for determination of enrofloxacin

Nowadays, bacterial resistance caused by the abuse of antibiotics has become a worldwide problem. In this work, a quinolone antibiotic, enrofloxacin (ENR), was rapidly monitored by combining a selective molecular imprinting polymer (MIP) with the electrochemiluminescence (ECL) method. Zn-PTC, a novel zinc-based metal-organic framework (MOF) that has a large specific surface area and ultra-high luminous efficiency, was used as the ECL luminophore. Chitosan (CHIT) was used to contact the specific surface area of molecularly imprinted polymer films and further improved the detection sensitivity. Subsequently, the molecularly imprinted polypyrrole was electropolymerized on the surface of the Zn-PTC and CHIT modified glassy carbon electrode (GCE). The specific sites that could target recombining ENR were shaped on the surface of MIP after extracting the ENR templates. The specific concentrations of ENR could be detected according to the difference in ECL intensity (ΔECL) between the eluting and rebinding of ENR. After optimization, a good linear response of ΔECL and a logarithm of specific ENR concentrations could be obtained in the range of 1.0 × 10-12-1.0 × 10-4 mol L-1, with a detection limit of 9.3 × 10-13 mol L-1 (S/N = 3). Notably, this study provided a rapid, convenient, and cheap method for the detection of ENR in actual samples.

Advanced experimental techniques for the sensitive detection of a toxic bisphenol A using UiO-66-NDC/GO-based electrochemical sensor

In the present study, a simple and sensitive method for detecting bisphenol A (BPA) in various environments, including groundwater, was described using a widespread electrochemical method. BPA is well-known for its endocrine-disrupting properties, which may cause potential toxicological effects oon the nervous, reproductive, and immune systems. A novel metal-organic framework (UiO-66-NDC/GO) was synthesized, and its existence was confirmed by several characterization techniques like FTIR, UV-visible, XRD, SEM-EDX, Raman spectroscopy, and TGA. Due to the excellent electrocatalytic nature, UiO-66-NDC/GO was chosen as the sensor material and integrated on the surface of the bare carbon paste electrode (BCPE). The UiO-66-NDC/GO modified carbon paste electrode (MCPE) was engaged for the detection of BPA using techniques like cyclic Voltammetry (CV), differential pulse voltammetry (DPV), and electrochemical impedance spectroscopy (EIS). The applied sensor exhibited an astonishing outcome for BPA detection with high sensitivity and selectivity. The lower detection limit (LLOD) of 0.025 μM was achieved at the modified sensor with a linear concentration range of 10-70 μM. Moreover, the practical applicability of the sensor was tested on tap water, drinking water, and fresh liquid milk, giving an excellent recovery of BPA in the range of 94.8-99.3 (v.%). The proposed method could be employed for electrochemical device or a solid state device fabrication for the onsite monitoring of BPA.

Signal-on electrochemiluminescence aptasensor for bisphenol A based on hybridization chain reaction and electrically heated electrode

A simple and sensitive electrochemiluminescence (ECL) aptasensor has been developed for bisphenol A (BPA) detection. The capture DNA (CDNA) was modified on the heated indium-tin-oxide (ITO) working electrode surface firstly and then hybridized with BPA aptamer to form double strand DNA (dsDNA). The presence of target can cause the releasing of aptamer from the electrode surface since the aptamer prefers to switch its configuration to combine with BPA. Subsequently, the free CDNA will induce hybridization chain reaction (HCR) to produce long dsDNA on the electrode surface. Ru(phen)₃²⁺ can integrate into the grooves of dsDNA to act as an ECL reagent, thus enhanced ECL signal can be detected. The temperature control during the processes of target recognition and HCR were realized through the heated electrode instead of the bulk solution heating. Furthermore, the performance of the ECL aptasensor can be further enhanced at elevated electrode temperature. Under the optimized conditions, the ECL intensity of the system has a linear relationship with the logarithm of BPA concentration in the range of 2.0 pM-50 nM. The limit of detection (LOD) at 55 °C (electrode surface temperature) was calculated to be 1.5 pM, which was approximately 6.5-fold lower than that at 25 °C. The proposed biosensor has been applied to detect the BPA in drink samples with satisfactory results.

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.

An Electrochemiluminescence Sensor Based on Nafion/Magnetic Fe₃O₄ Nanocrystals Modified Electrode for the Determination of Bisphenol A in Environmental Water Samples

The well-dispersive and superparamagnetic Fe₃O₄-nanocrystals (Fe₃O₄-NCs) which could significantly enhance the anodic electrochemiluminescence (ECL) behavior of luminol, were synthesized in this study. Compared to ZnS, ZnSe, CdS and CdTe nanoparticles, the strongest anodic ECL signals were obtained at +1.6 V on the Fe₃O₄-NCs coated glassy carbon electrode. The ECL spectra revealed that the strong ECL resonance energy transfer occurred between luminol and Fe₃O₄-NCs. Furthermore, under the optimized ECL experimental conditions, such as the amount of Fe₃O₄-NCs, the concentration of luminol and the pH of supporting electrolyte, BPA exhibited a stronger distinct ECL quenching effect than its structural analogs and a highly selective and sensitive ECL sensor for the determination of bisphenol A (BPA) was developed based on the Fe₃O₄-NCs. A good linear relationship was found between the ECL intensity and the increased BPA concentration within 0.01⁻5.0 mg/L, with a correlation coefficient of 0.9972. The detection limit was 0.66 × 10^-3 mg/L. Good recoveries between 96.0% and 105.0% with a relative standard deviation of less than 4.8% were obtained in real water samples. The proposed ECL sensor can be successfully employed to BPA detection in environmental aqueous samples.

Trends and Advances in Electrochemiluminescence Nanobiosensors

The rapid and increasing use of the nanomaterials (NMs), nanostructured materials (NSMs), metal nanoclusters (MNCs) or nanocomposites (NCs) in the development of electrochemiluminescence (ECL) nanobiosensors is a significant area of study for its massive potential in the practical application of nanobiosensor fabrication. Recently, NMs or NSMs (such as AuNPs, AgNPs, Fe₃O₄, CdS QDs, OMCs, graphene, CNTs and fullerenes) or MNCs (such as Au, Ag, and Pt) or NCs of both metallic and non-metallic origin are being employed for various purposes in the construction of biosensors. In this review, we have selected recently published articles (from 2014-2017) on the current development and prospects of label-free or direct ECL nanobiosensors that incorporate NCs, NMs, NSMs or MNCs.

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.