Tannic acid functionalized N-doped graphene modified glassy carbon electrode for the determination of bisphenol A in food package

A Status Update on the Development of Polymer and Metal-Based Graphene Electrochemical Sensors for Detection and Quantitation of Bisphenol A

The detection and quantitation of bisphenol A (BPA) in the environment and food products has been a subject of considerable interest. BPA, a diphenylmethane derivative is a well-known industrial raw material with wide range of applications. It is a well-known endocrine disruptor and acts as an estrogen mimic. BPA is an environmental health concern and its accumulation in hydro-geological cycles is a matter of serious ecological peril. This review basically assesses various chemically modified electrodes composed of diverse components that have been employed to recognize BPA in different matrices. Electrochemical sensors prepared using graphene materials in combination with metals and polymers for selective detection of BPA have been discussed extensively. The emphasis is on detection of BPA in various samples encountered in routine use such as plastic bottles, receipts, baby feed bottles, milk samples, mineralized water, tissue paper, DVDs, and others. Although research in this field is in the exploratory stage, deeper insights into fundamental studies of sensing systems, fast analysis of real samples and validation of sensors are some of the factors that need major impetus. It is expected that chemically modified electrode-based sensing systems will soon take over as a viable option for monitoring diverse pollutants.

Electrochemical sensors based on carbon nanostructures for the analysis of bisphenol A-A review

Overuse of Bisphenol A (BPA), a proven endocrine disruptor, has become a serious public health problem across the world. It has the potential to harm both the environment and human health, notably reproductive disorders, heart disease, and diabetes. Accordingly, much attention has been paid to the detection of BPA to promote food safety and environmental health. Carbon based nanostructures have proven themselves well in a variety of applications, such as energy storage, catalysis and sensors, due to their remarkable properties. Therefore, researchers have recently focused on fabricating electrochemical BPA sensors based on carbon nanostructures due to their unique advantages, such as real-time monitoring, simplicity, high selectivity, high sensitivity and easy operation. The purpose of the current review was to summarize the recent findings on carbon nanostructures for electrochemically sensing the BPA, as well as relevant future prospects and ongoing challenges.

A facile synthesis of nanostructured CoFe2O4 for the electrochemical sensing of bisphenol A

This work reports a novel, highly sensitive and cost-effective electrochemical sensor for the detection of bisphenol A in environmental water samples. Attractive non-noble transition metal oxide CoFe₂O₄ nanoparticles were successfully synthesized using a sol–gel combustion method and further characterized by X-ray diffraction, scanning electron microscopy and X-ray photoelectron spectroscopy. Under optimal conditions, the CoFe₂O₄ nanoparticle modified glassy carbon electrode exhibits high electrochemical activity and good catalytic performance for the detection of bisphenol A. The linear calibration curves are obtained within a wide concentration range from 0.05 μmol L⁻¹ to 10 μmol L⁻¹, and the limit of detection is 3.6 nmol L⁻¹ for bisphenol A. Moreover, this sensor also demonstrates excellent reproducibility, stability, and good anti-interference ability. The sensor was successfully applied to determine bisphenol A in practical samples, and the satisfactory recovery rate was between 95.5% and 102.0%. Based on the great electrochemical properties and practical application results, this electrochemical sensor has broad application prospects in the sensing of bisphenol A.

A new electrochemical sensor for bisphenol A is reported. CoFe₂O₄ nanoparticles were synthesized by a sol–gel combustion method. A nanoparticle-modified glassy carbon electrode exhibited outstanding electrochemical performance for the detection of bisphenol A.

Highly-sensitive and selective determination of bisphenol A in milk samples based on self-assembled graphene nanoplatelets-multiwalled carbon nanotube-chitosan nanostructure

Graphene nanoplatelets (GNPs), multiwalled carbon nanotube (MWCNTs) and chitosan (CS) were self-assembled by a facile one-step hydrothermal reaction to obtain novel MWCNTs-CS enfolded GNPs (GNPs-MWCNTs-CS) composite. Fourier transform infrared (FT-IR) spectroscopy, Raman spectroscopy, scanning electron microscopy (SEM), UV-visible (UV-vis) absorption spectroscopy and zeta potential analysis were employed to characterize the morphology, surface composition, interaction, surface charge and stability of the GNPs-MWCNTs-CS composite. The electrochemical behaviors of GNPs-MWCNTs-CS composite modified glassy carbon electrode (GNPs-MWCNTs-CS/GCE) were investigated using cyclic voltammetry (CV) and electrochemical impedance spectroscopy (EIS). The GNPs-MWCNTs-CS/GCE was used for fast and high sensitive determination of bisphenol A (BPA) by differential pulse voltammetry (DPV). Under the optimum conditions, the calibration curve obtained is linear for the current versus the BPA concentration in the range 0.1-100 μM with a detection limit of 0.05 nM (signal-to-noise ratio of 3, S/N = 3). The between-sensor reproducibility was 1.29% (n = 6) for 0.04 mM BPA. The proposed GNPs-MWCNTs-CS/GCE based sensor showed high resistance to interference, good repeatability and excellent reproducibility. Trace BPA in milk samples could also be reliably determined.

Universal method for direct bioconjugation of electrode surfaces by fast enzymatic polymerization

We report HRP-catalyzed polymerization of Tannic acid (TA) and application of the poly (Tannic acid) (p(TA)) as a versatile platform for covalent immobilization of biomolecules on various electrode surfaces based on electrochemical oxidation of the p(TA) and subsequent oxidative coupling reactions with the biomolecules. We also used this method for capturing cancer cells through a linker molecule, folic acid (FA). Furthermore, we have demonstrated that enhanced electrocatalytic activity of the p(TA)-modified surface could be used for simultaneous electrochemical determination of biologically important electroactive molecules such as ascorbic acid (AA), dopamine (DA), and uric acid (UA). This HRP-catalyzed polymerization of TA and p(TA)-mediated surface modification method can provide a simple and new framework to construct multifunctional platforms for covalent attachment of biomolecules and development of sensitive electrochemical sensing devices.

Dispersive solid-phase extraction with tannic acid functionalized graphene adsorbent for the preconcentration of trace beryllium from water and street dust samples

In this study, tannic acid functionalized graphene as an adsorbent was synthesized and characterized by X-ray diffraction and scanning electron microscopy. It was used for the first time as an adsorbent for vortex-assisted dispersive solid phase extraction of trace Be(II) from water and street dust samples. The determination of beryllium was made by graphite furnace atomic absorption spectrometry. The effect of different parameters (pH, contact times, centrifuge rate and time, eluent type and volume, sample volume, and interfering ions) was investigated. The optimum pH was found to be 6. The adsorption and elution contact times were 3 min. The quantitative elution was carried out with 2 mL of 1.5 mol L^-1 HCl. The preconcentration factor, detection limit and precision (as RSD%) of the method were found to be 125, 0.84 ng L^-1, and 2.9%, respectively. The adsorbent showed good selectivity for Be(II) against interfering cations and anions and it was reusable up to 80 cycles. The accuracy of the developed method was confirmed by analyzing certified reference material (TMDA-70 Lake water) and by spiking tap water, wastewater, well water, and street dust samples.

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.

Facile synthesis of 3D porous nitrogen-doped graphene as an efficient electrocatalyst for adenine sensing

We demonstrate a simple, low-cost and eco-friendly strategy for the convenient preparation of three-dimensional porous nitrogen-doped graphene (3D-N-GN) for the highly sensitive detection of adenine.

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.

Chemometrics-assisted cyclodextrin-enhanced excitation-emission fluorescence spectroscopy for the simultaneous green determination of bisphenol A and nonylphenol in plastics

The aim of this work was to quantify two relevant priority chemicals, bisphenol A (BPA) and 4-nonylphenol (NP), coupling the sensitivity of fluorescence in organized media and the selectivity of multivariate calibration, measuring excitation-emission fluorescence matrices in an aqueous methyl-β-cyclodextrin solution. The studied priority pollutants are two of the most frequently found xenoestrogens in the environment, and are therefore of public health concern.The data were successfully processed by applying unfolded partial least-squares coupled to residual bilinearization (U-PLS/RBL), which provided the required selectivity for overcoming the severe spectral overlapping among the analyte spectra and also those for the interferents present in real samples. A rigorous International Union of Pure and Applied Chemistry (IUPAC)-consistent approach was applied for the calculation of the limits of detection. Values in the ranges of 1-2 and 4-14 ng mL(-1) were obtained in validation samples for BPA and NP, respectively. On the other hand, low relative prediction errors between 3% and 8% were achieved. The proposed method was successfully applied to the determination of BPA and NP in different plastics. In positive samples, after an easy treatment with a small volume of ethanol at 35°C, concentrations were found to range from 26 to 199 ng g(-1) for BPA, and from 95 to 30,000 ng g(-1) for NP.

A nitrogen and sulfur co-doped graphene-supported nickel tetrapyridyloxyphthalocyanine hybrid fabricated by a solvothermal method and its application for the detection of bisphenol A

A novel hybrid consisting of nickel tetrapyridyloxyphthalocyanine (NiTPPc) and nitrogen and sulfur co-doped graphene (N-S-G) was obtained via a solvothermal method and applied for the determination of BPA.

Azo dye functionalized graphene nanoplatelets for selective detection of bisphenol A and hydrogen peroxide

A new electrochemical sensor is developed based on graphene nanoplatelets functionalized with tri-azo dye (direct blue 71) for selective and highly sensitive detection of bisphenol A and hydrogen peroxide in pH 7 phosphate buffered saline solution.