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A novel electropolymerizable material, 1-[3-(N-pyrrolyl) propyl]-3-butylimidazolium bromide (NPBimBr) ionic liquid, was synthesized and used as a modifier to functionalize graphene oxide nanosheets (GO) for fabricating an electrochemical sensor. X-ray photoelectron spectroscopy, transmission electron microscopy, scanning electron microscopy and electrochemical impedance spectroscopy were used to characterize both GO-NPBimBr and GO-poly(NPBimBr) film electrode. Electrochemical performance in the detection of bisphenol A at the GO-poly(NPBimBr) modified glassy carbon electrode (GCE) was investigated and optimized. Compared with the bare GCE, the oxidation peak current of bisphenol A at the nanocomposite film modified electrode was significantly increased. A good linear relationship between the oxidation peak current and the bisphenol A concentration was found in the range of 2.0 × 10 −7 ∼ 1.0 × 10 −5 mol L −1 , with a detection limit of 1.7 × 10 −8 mol L −1 . The method was successfully applied to determine bisphenol A content in commercially available plastic drinking cups and the results are consistent with the ones from high performance liquid chromatography. [ABSTRACT FROM AUTHOR]

The ionic liquid 1-{3-[(2-aminoethyl)amino]propyl}-3-vinylimidazole bromide was synthesized and used to fabricate a molecularly imprinted film for electrochemical sensing of myoglobin (Myo). This film was deposited on a glassy carbon electrode modified with multi-walled carbon nanotubes by using the ionic liquid as the functional monomer, Myo as the template, N,N′-methylenebisacrylamide as the crosslinker, and a redox system containing ammonium persulfate and N,N,N′,N′-tetramethylethylenediamine as the initiator. The sensing performance of the modified electrode was investigated by using the hexacyanoferrate system as an electrochemical redox probe. The results demonstrated that the sensor possesses good selectivity and high sensitivity. The oxidation peak current at the potential of ~0.3 V (vs. SCE) was found linearly related to the myoglobin concentration in the range from 60.0 nM to 6.0 μM, with a 9.7 nM detection limit at an S/N ratio of 3. The sensor was applied to the determination of Myo in spiked serum samples where it showed average recoveries (for n = 5) of 96.5 %. [ABSTRACT FROM AUTHOR]

Reduced graphene oxide (rGO) nanosheets functionalized with 1,3-di(4-amino-1-pyridinium) propane tetrafluoroborate ionic liquid (DAPPT) was successfully synthesized and fully characterized. DAPPT-rGO nanosheets were coated to a glassy carbon electrode (GCE) surface to immobilize tyrosinase (Tyr). The Tyr-DAPPT-rGO/GCE was characterized with scanning electronic microscopy and electrochemical impedance spectroscopy. The biosensor shows a linear response to bisphenol A (BPA) in the concentration range of 1.0×10−9∼3.8×10−5 mol L−1. The detection limit was calculated to be 3.5×10−10 mol L−1 (S/N=3). The practical application was demonstrated by determining BPA leaching from commercial plastic drinking bottles. [ABSTRACT FROM AUTHOR]

The ionic liquid 1-butyl -3-[3-(N-pyrrole)-propyl]imidazolium tetrafluoroborate was employed to fabricate a glassy carbon electrode (GCE) modified with a porous film of a polymerized ionic liquid. The resulting film electrode was treated with sodium dodecyl sulfonate solution to exchange the terafluoroborate anions by dodecyl sulfonate groups. This was confirmed by X-ray photoelectron spectroscopy. The morphology of the modified GCE was characterized by scanning electron microscopy and revealed a nanoporous surface. The electrochemical properties of this film electrode were studied by electrochemical impedance spectroscopy using the hexacyanoferrate(II/III) system as an electroactive probe. The response to bisphenol A was investigated by voltammetry. Compared to the unmodified GCE, the oxidation potential is positively shifted, and the oxidation peak current is strongly increased. Experimental conditions were optimized and resulted in an oxidation peak current that is linearly related to concentration of bisphenol A in the 10 nM to ~ 10 μM range. The detection limit is 8.0 nM (at S/ N = 3). The electrode was successfully applied to the determination of bisphenol A in leachates of plastic drinking bottles, and its accuracy was verified by independent assays via HPLC. [Figure not available: see fulltext.] [ABSTRACT FROM AUTHOR]

Abstract: Parathion imprinted polymer beads were prepared by free radical polymerization using parathion as template, methacrylic acid as functional monomer, divinyl benzene as cross-linking reagent and 2,2′-azobis(isobutyronitrile) as initiator. The obtained molecularly imprinted beads were characterized with transmission electron micrograph. The rebinding properties of these imprinted beads towards parathion were studied by saturation binding experiments using ultraviolet/visible spectroscopy. Effects of the template, functional monomer, cross-linking reagent and initiator on selective adsorption of parathion were investigated. The high selectivity of the imprinted beads was successfully demonstrated by their selective adsorption of free parathion from an ethanol–water (v/v=1:5) solution. In addition, the parathion imprinted beads were dispersed into dihexadecyl hydrogen phosphate solution at the concentration of 1.0mgmL−1. By coating this solution onto a glassy carbon electrode surface, a molecularly imprinted electrochemical sensor for parathion was obtained. The electrochemical sensor exhibited good selectivity and fast response to parathion. Under optimized experimental conditions, the peak currents were found linearly proportional to the parathion concentration in the range of 1.0×10−7 molL−1 to 1.0×10−5 molL−1 with a detection limit of 5.4×10−8 molL−1 (S/N=3). The developed sensor was successfully employed for the determination of parathion in pear juice samples. [Copyright &y& Elsevier]

A molecularly imprinted sensor was fabricated for alpha-fetoprotein (AFP) using an ionic liquid as a functional monomer. Ionic liquid possesses many excellent characteristics which can improve the sensing performances of the imprinted electrochemical sensor. To demonstrate this purpose, 1-[3-(N-cystamine)propyl]-3-vinylimidazolium tetrafluoroborate ionic liquid [(Cys)VIMBF4] was synthesized and used as a functional monomer to fabricate an AFP imprinted polymerized ionic liquid film on a gold nanoparticle modified glassy carbon electrode (GCE) surface at room temperature. After removing the AFP template, a molecularly imprinted electrochemical sensor was successfully prepared. The molecularly imprinted sensor exhibits excellent selectivity towards AFP, and can be used for sensitive determination of AFP. Under the optimized conditions, the imprinted sensor shows a good linear response to AFP in the concentration range of 0.03 ng mL−1~5 ng mL−1. The detection limit is estimated to be 2 pg mL−1. [ABSTRACT FROM AUTHOR]

Organic pollutants are highly biological toxicity to public health and environments. Their sensitive detection is highly required. Herein, a new electrochemical interface for sensitive and selective minoring of tetrabromobisphenol A (TBBPA), sunset yellow (SY), and tartrazine (Tr) is then developed with the composite of Fe 2 O 3 nanomaterials and expanded graphite (EG) as the sensing materials. Three Fe 2 O 3 nanomaterials, synthesized via a hydrothermal method, feature the morphologies of nanoplate, nanorod, and a three-dimensional flower-like (f-Fe 2 O 3) structure. Electrochemical activity of these nanocomposites is found to be dependent on the morphology of synthesized Fe 2 O 3 nanomaterials. The composite of f-Fe 2 O 3 /EG displays the biggest electrochemical active area and the lowest electron transfer resistance towards redox probes, due to a 3D porous hierarchical structure of f-Fe 2 O 3 and a high conductivity of EG. The best sensing performance of three pollutants was thus achieved on this composite coated electrode with a limit of detection of 1.23, 0.89 and 2.17 nM for TBBPA, SY, and Tr, respectively. Image 1049 • Facile synthesis of nanoplate, nanorod, and three-dimensional flower-like Fe 2 O 3 structures. • Morphology-dependent electrochemistry of Fe 2 O 3 nano-structures. • Sensitive and selective monitoring of different environmental pollutants. [ABSTRACT FROM AUTHOR]

Ionic liquid functionalized tungsten disulfite nanosheets (IL-WS 2 ) were prepared by using 1-vinyl-3-(3-aminopropyl)-imidazolium bromide (VAPimBr) ionic liquid as an auxiliary reagent to exfoliate WS 2 bulk crystals in N-methyl pyrrolidone with ultrasonication. Hollow gold nanospheres (HGNs) were controllably synthesized by using 1,3-di(3-bromopropyl)-imidazolium bromide ionic liquid as the functional monomer. HGNs were integrated onto IL-WS 2 nanosheet surface to fabricate a HGNs/IL-WS 2 nanocomposite through the interaction between S and Au atoms. VAPimBr ionic liquid and HGNs can significantly enhance the photocurrent response of IL-WS 2 nanosheets. Human epididymis protein 4 antibody (anti-HE4) was immobilized onto the HGNs/IL-WS 2 nanocomposite modified glassy carbon electrode (GCE) surface. Followed by being treated with glutaraldehyde vapor and bovine serum albumin (BSA), a photoelectrochemical immunosensor for human epididymis protein 4 (HE4) was successfully constructed and denoted as anti-HE4/HGNs/IL-WS 2 /GCE. The photoelectrochemical variation upon interacting with HE4 was used for the quantitative assay. Experimental conditions including the exfoliation time, the amount of VAPimBr ionic liquid, HGNs size, ascorbic acid concentration, incubation time, incubation temperature have been optimized. Under optimal conditions, HE4 was determined by using the photoelectrochemical immunosensor in a dynamic linear range from 0.1 pg mL −1 to 10 ng mL −1 with a detection limit of 0.03 pg mL −1 (S/N = 3). HE4 in clinical serum samples were also accurately determined with satisfied results. [ABSTRACT FROM AUTHOR]

A molecularly imprinted polymer film was in situ polymerized on a carboxyl functionalized multi-walled carbon nanotubes modified glassy carbon electrode surface under room temperature. This technique provides a promising imprinting approach for protein in an aqueous solution using 3-(3-aminopropyl)-1-vinylimidazolium tetrafluoroborate ionic liquid as functional monomer, N, N′-methylenebisacrylamide as crossing linker, ammonium persulfate and N,N,N′,N′-tetramethylethylenediamine as initiator, and bovine serum albumin (BSA) as template. The molecularly imprinted polymerized ionic liquid film shows enhanced accessibility, high specificity and sensitivity towards BSA. Electrochemical sensing performance of the imprinted sensor was thoroughly investigated using K 3 Fe[CN] 6 /K 4 Fe[CN] 6 as electroactive probes. Under optimal conditions, the current difference before and after specific recognition of BSA was found linearly related to its concentration in the range from 1.50×10 −9 to 1.50×10 −6 mol L −1 . The detection limit was calculated to be 3.91×10 −10 mol L −1 ( S / N =3). The practical application of the imprinted sensor was demonstrated by determining BSA in liquid milk samples. [ABSTRACT FROM AUTHOR]

Highlights: [•] Electrochemical fabrication of a novel ionic liquid based polymeric film electrode. [•] Studies on voltammetric behaviors of estradiol at the polymeric film electrode. [•] Effective oxidation peak current for the voltammetric determination of estradiol. [•] Application of the polymeric film electrode for estradiol assay in real sample. [ABSTRACT FROM AUTHOR]

Highlights: [•] Single-walled carbon nanotubes (SWCNTs)-ionic liquid (IL) nanocomposite fabrication. [•] SWCNTs-Poly-IL film modified electrode was prepared and characterized. [•] Voltammetric behaviors of bisphenol A were investigated thoroughly. [•] Sensitive voltammetric method for bisphenol A determination was developed. [Copyright &y& Elsevier]

Abstract: New graphene–silk peptide (Gr–SP) nanosheets were prepared and successfully fabricated with tyrosinase (Tyr) as a novel biosensor for the determination of phenolic compounds. The Gr–SP nanosheets were fully characterized with transmission electron microscopy, x-ray diffraction, x-ray photoelectron spectroscopy, UV/Vis and FTIR spectra. The developed biosensors were also characterized with scanning electronic microscopy and electrochemical impedance spectroscopy. Using bisphenol A (BPA) as a model substrate in the sensing system, a number of key factors including the volume of Gr–SP–Tyr solution, the applied potential, pH values, temperature, and the Tyr/Gr–SP ratio that influence the analytical performance of the biosensor were investigated. The biosensor gave a linear response on the concentration ranges of 0.001–16.91μM for catechol with the sensitivity of 7634mAM−1 cm−2, 0.0015–21.12μM for phenol with the sensitivity of 4082mAM−1 cm−2, and 0.002–5.48μM for BPA with the sensitivity of 2511mAM−1 cm−2. The low detection limits were estimated to be 0.23, 0.35 and 0.72nM (S/N=3) for catechol, phenol and BPA, respectively. The biosensors also exhibit good repeatability and long-term stability. The practical application of the biosensor was also demonstrated by the determination of BPA leaching from commercial plastic drinking bottles. [Copyright &y& Elsevier]