New Aptamer/MoS2/Ni-Fe LDH Photoelectric Sensor for Bisphenol A Determination

Here, a new type of PEC aptamer sensor for bisphenol A (BPA) detection was developed, in which visible-light active MoS2/Ni-Fe LDH (layered double hydroxide) heterostructure and aptamer were used as photosensitive materials and biometric elements, respectively. The combination of an appropriate amount of MoS2 and Ni-Fe LDH enhances the photocurrent response, thereby promoting the construction of the PEC sensor. Therefore, we used a simple in situ growth method to fabricate a MoS2/Ni-Fe LDH sensor to detect the BPA content. The aptasensor based on aptamer/MoS2/Ni-Fe LDH displayed a linear range toward a BPA of 0.05–10 to 50–40,000 ng L−1, and it has excellent stability, selectivity and reproducibility. In addition, the proposed aptamer sensor is effective in evaluating real water samples, indicating that it has great potential for detecting BPA in real samples.

Synthesis of N-rGO-MWCNT/CuCrO2 Catalyst for the Bifunctional Application of Hydrogen Evolution Reaction and Electrochemical Detection of Bisphenol-A

A glassy carbon electrode (GCE) coated with delafossite CuCrO2 loading on the nitrogen-doped reduced graphene oxide (N-rGO) and multiwalled carbon nanotubes (MWCNT) composite (N-rGO-MWCNT/CuCrO2) was applied to the hydrogen evolution reaction and Bisphenol-A (BPA) detection. First, the N-rGO-MWCNT composite was prepared by in situ chemical reduction with caffeic acid as a reducing agent. Then, CuCrO2 was accumulated on the N-rGO-MWCNT surface to form N-rGO-MWCNT/CuCrO2 composite. The morphology structure of the N-rGO-MWCNT/ CuCrO2 composite was analyzed by different characterization techniques. Besides, the GCE/N-rGO-MWCNT/CuCrO2 composite electrode was investigated for hydrogen evolution reaction (HER), which shows an excellent electrocatalytic activity with a low over-potential, increasing reduction current, and a small Tafel slope of 62 mV·dec−1 at 10 mA·cm−2 with long-term stability. Moreover, the electrochemical determination of BPA was in the range of 0.1-110 µM, and low detection limit of 0.033 µM (S/N = 3) with a higher sensitivity of 1.3726 µA µM−1 cm−2. Furthermore, the prepared GCE/N-rGO-MWCNT/CuCrO2 electrode shows effective detection of BPA in food samples with acceptable recoveries. Hence, the finding of GCE/N-rGO-MWCNT/CuCrO2 can be observed as an impressive catalyst to the electrocatalytic activity of HER and BPA oxidation.

Ratiometric electrochemical sensor for bisphenol A detection using glassy carbon electrode modified with poly(toluidine blue)/gold nanoparticle composite

A ratiometric electrochemical sensor for bisphenol A (BPA) detection is established using glassy carbon electrode modified with poly(toluidine blue)/gold nanoparticle composite (PTB/AuNP/GCE). The ratiometric signal, namely, the oxidation peak current...

Metal Organic Frame-Upconverting Nanoparticle Assemblies for the FRET Based Sensor Detection of Bisphenol A in High-Salt Foods

To resolve the occurrence of unfulfillable detection in high-salts foods, we used fluorescence resonant energy transfer (FRET) sensors based on nanoparticle upconversion. In this study, we developed a novel FRET sensor for the detection of bisphenol A (BPA) in high-salt foods. We based this approach on the assembly of aptamer modified upconversion nanoparticles (DNA1-UCNPs) and complementary DNA modified metal organic frames (DNA2-MOFs), which possessed corresponding wavelength absorption. Targeting BPA signal transduction was performed using the BPA aptamer, via competitive recognition between the BPA analyte and complementary DNA sequences in a high-salt solution. Sensor adaption in high-salt samples was attributed to functional hydrophilic groups, modified in the MOFs, and the enhanced colloidal stability of these MOFs. The MOF-UCNP assembly displayed considerable analytical performance in terms of BPA detection, with a linear range of 0.1–100 nM, and a limit of detection (LOD) of 0.02 nM, in a 340 mM NaCl food sample (the energy drink, Gatorade). Thus, this method provides a solid basis for small molecules detection in high-salt foods.

Physical and Electrochemical Characterization of Modified Graphite Nanoparticles-Phosphotungstic Acid-Nafion on Glassy Carbon Electrode for Bisphenol A Determination

A simple and rapid electrochemical sensor based on modified graphite nanoparticle with phosphotungstic acid and Nafion (GN–PTA–nafion) on glassy carbon electrode (GCE) has been developed for detecting bisphenol A (BPA). The GN was characterized using a scanning electron microscope (SEM) and X-ray diffractometer (XRD), while the modified GCE was characterized using differential pulse voltammetry (DPV) and cyclic voltammetry (CV). Several parameters such as GN concentration, scan rate, equilibrium time, and pH of phosphate buffer were optimized in this study. The GN–PTA–Nafion modified GCE that consists of graphite nanoparticle with a large surface area showed better and faster electron transfer, whereas the phosphotungstic acid (PTA) increased the sensitivity of the electrode for BPA detection. Good electrochemical performances for analyzing BPA, with a detection limit of 0.3995 mol L-1, as well as good reproducibility (RSD 2.51%) were obtained. The modified electrode showed that it had short analysis time, inexpensive and good sensitivity for BPA detection.

Molecular Imprinting of Bisphenol A on Silica Skeleton and Gold Pinhole Surfaces in 2D Colloidal Inverse Opal through Thermal Graft Copolymerization

This study successfully fabricated BPA-imprinted poly(4-vinylpyridine-co-ethylene glycol dimethacrylate) (poly(4-VP-co-EGDMA)) quartz crystal microbalance (MIP-QCM) sensors on a silica skeleton surface and gold pinholes of silica inverse opal through surface-initiated atom transfer radical polymerization (SI-ATRP). The sensing features of the two MIP films on the structured silica surface and nano-scale local gold surface were investigated by measuring the resonant frequency change (∆f) in QCM sensors. The ∆f values for the p-MIP (MIP on gold pinholes) and s-MIP films (MIP on silica skeleton surface) were obtained with the ∆f value of −199 ± 4.9 Hz and −376 ± 19.1 Hz, respectively, whereas for p-/s-NIP films, the ∆f values were observed to be −115 ± 19.2 Hz and −174 ± 5.8 Hz by the influence of non-specific adsorption on the surface of the films. Additionally, the imprinting factor (IF) appeared to be 1.72 for p-MIP film and 2.15 for s-MIP film, and the limits of quantitation (LOQ) and detection (LOD) were 54.924 and 18.125 nM (p-MIP film) and 38.419 and 12.678 nM (s-MIP film), respectively. Using the Freundlich isotherm model, the binding affinity of the BPA-imprinted films was evaluated. This was measured in an aqueous solution of BPA whose concentration ranged between 45 and 225 nM. It was found that the p-MIP film (m = 0.39) was relatively more heterogeneous than the s-MIP film (m = 0.33), both of which were obtained from the slope of the linear regressions. Finally, the selectivity of the MIP-QCM sensors for BPA detection was determined by measuring the effect of other analogous chemicals, such as bisphenol F (BPF), bisphenol AP (BPAP), and bisphenol B (BPB), in aqueous solutions. The selectivity coefficients (k*) of the two MIP films had ~1.9 for the p-MIP and ~2.3 for the s-MIP films, respectively. The results reveal that, with respect to signal amplification of the QCM sensors, the s-MIP film has better sensing features and faster detection responses than the p-MIP film.

Development of a new bisphenol A electrochemical sensor based on a cadmium(ii) porphyrin modified carbon paste electrode

In this study, the (5,10,15,20-tetrakis[(4-methoxyphenyl)]porphyrinato)cadmium(ii) complex ([Cd(TMPP)]) was successfully used as a modifier in a carbon paste electrode (CPE) and exploited for bisphenol A (BPA) detection.

DETECTION OF BISPHENOL A CONTAMINATION IN CANNED CARBONATED BEVERAGES BY GAS CHROMATOGRAPHY

Objective: The purpose of this study was to develop sensitive, selective, and valid methods for the detection of bisphenol A (BPA) contamination inbeverage samples using gas chromatography (GC)-flame ionization.Methods: The optimized analysis system employed a long HP-1 capillary column (30 m, inner diameter 0.25 mm, film thickness 0.25 μm), gradientcolumn temperature (150°C–260°C at 10°C/min), and nitrogen as a carrier gas (1 mL/min). Samples were prepared for analysis using ethyl acetateas the extraction solvent.Results: This method yielded a linearity coefficient of 0.9998, while the limit of detection (LOD) and limit of quantitation (LOQ) were 0.287 μg/mL and0.956 μg/mL, respectively. All validation parameters, including linearity, selectivity, accuracy, precision, LOD, and LOQ, meet recognized acceptabilitycriteria. Contamination analysis showed that one of the three beverage brands tested contained 2.4090 μg/mL BPA, and contamination was evenhigher after heating.Conclusion: BPA contamination may occur in canned beverages, especially under improper storage conditions. This GC-based BPA detection systemmay be useful for the detection of BPA contamination in consumer beverages.