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ABSTRACT: Surface-imprinted core-shell Au nanoparticles (AuNPs) were explored for the highly selective detection of bisphenol A (BPA) by surface-enhanced Raman scattering (SERS). A triethoxysilane-template complex (BPA-Si) was synthesized and then utilized to fabricate a molecularly imprinted polymer (MIP) layer on the AuNPs via a sol-gel process. The imprinted BPA molecules were removed by a simple thermal treatment to generated the imprint-removed material, MIP-ir-AuNPs, with the desired recognition sites that could selectively rebind the BPA molecules. The morphological and polymeric characteristics of MIP-ir-AuNPs were investigated by transmission electron microscopy and Fourier-transform infrared spectroscopy. The results demonstrated that the MIP-ir-AuNPs were fabricated with a 2nm MIP shell layer within which abundant amine groups were generated. The rebinding kinetics study showed that the MIP-ir-AuNPs could reach the equilibrium adsorption for BPA within 10min owning to the advantage of ultrathin core-shell nanostructure. Moreover, a linear relationship between SERS intensity and the concentration of BPA on the MIP-ir-AuNPs was observed in the range of 0.5-22.8mgL(-1), with a detection limit of 0.12mgL(-1) (blank±3×s.d.). When applied to SERS detection, the developed surface-imprinted core-shell MIP-ir-AuNPs could recognize BPA and prevent interference from the structural analogues such as hexafluorobisphenol A (BPAF) and diethylstilbestrol (DES). These results revealed that the proposed method displayed significant potential utility in rapid and selective detection of BPA in real samples.
Analytica chimica acta 05/2013; 777:57-62. · 4.31 Impact Factor
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ABSTRACT: A method based on plasmon resonance Rayleigh scattering (PRRS) spectroscopy and dark-field microscopy (DFM) was established for the real-time monitoring of a click reaction at the single-nanoparticle level. Click reactions on the surface of single gold nanoparticles (GNPs) result in interparticle coupling, which leads to a red-shift of the λmax (Δλmax =43 nm) in the PRRS spectra and a color change of the single gold nanoparticles in DFM (from green to orange).
Angewandte Chemie International Edition 04/2013; · 13.45 Impact Factor
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ABSTRACT: A novel method for real-time monitoring of the oxidative response of a membrane-channel biomimetic system (MCBS) to free radicals is developed and the deduction of the buffering effect of MCBS is discussed.
Chemical Communications 04/2013; · 6.17 Impact Factor
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ABSTRACT: A Surface Enhanced Raman Scattering (SERS) substrate based on Ag/ b -AgVO 3 nanobelts deposited on copper foil (Cu@Ag/ b -AgVO 3 ) was used for the detection of carbamate pesticides: carbofuran, carbaryl, isoprocarb and propoxur. Cu@Ag/ b -AgVO 3 has shown an excellent SERS activity for carbamate pesticides compared to silver nanoparticles (AgNPs). Under optimized conditions, detection limits of 2.5 pM, 10 pM, 50 pM and 75 pM were obtained for carbaryl, carbofuran, isoprocarb and propoxur respectively, suggesting that Cu@Ag/ b -AgVO 3 is a good candidate for use as a SERS substrate for the trace level detection of these pesticides.
Analytical methods 02/2013; · 1.55 Impact Factor
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ABSTRACT: Here we report a protocol to investigate the electron-transfer processes of redox-active biomolecules in biological membranes by electrochemistry using biomimetic hybrid bilayer membranes (HBMs) assembled on gold electrodes. Redox-active head groups, such as the ubiquinone moiety, are embedded in HBMs that contain target molecules, e.g., nicotinamide adenine dinucleotide (NADH). By using this approach, the electron-transfer processes between redox molecules and target biomolecules are mediated by mimicking the redox cycling processes in a natural membrane. Also included is a procedure for in situ surface-enhanced Raman scattering (SERS) to confirm the electrochemically induced conformational changes of the target biomolecules in the HBMs. In addition, each step in constructing the HBMs is characterized by electrochemical impedance spectroscopy (EIS), high-resolution X-ray photoelectron spectroscopy (XPS) and atomic force microscopy (AFM). The time required for the entire protocol is ∼12 h, whereas the electrochemical measurement of electron-transfer processes takes less than 1 h to complete.
Nature Protocol 02/2013; 8(3):439-50. · 8.36 Impact Factor
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ABSTRACT: We report the spontaneous fragmentation of gold nanoparticles (AuNPs) induced, in aqueous solution at room temperature, by thiol derivative of ubiquinone, which involves the energetic electron injection from thiol-ubiquinone to the gold nanoparticles.
Chemical Communications 01/2013; · 6.17 Impact Factor
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ABSTRACT: A facile one-step approach to fabricate substrates for surface-enhanced Raman scattering (SERS) detection of polycyclic aromatic hydrocarbons (PAHs) was explored by reduction of silver nitrate with humic acids (HAs). This simple process readily delivers silver nanoparticles (Ag NPs) decorated with HAs (HAs-Ag NPs), and an average diameter of 50 nm. More importantly, it compares favorably to Ag NPs prepared by the usual sodium citrate method, HAs-Ag NPs show excellent SERS activity for PAHs and display a remarkable capacity to absorb aromatic molecules through presumed π-π stacking interactions. Furthermore, the HAs-Ag NPs displayed good SERS stability, possibly due to the fact that HAs form loose coils or networks around the nanoparticles thus preventing aggregation. The investigation of qualitative and quantitative detection of PAHs on HAs-Ag NPs indicate that different PAHs can be distinguished easily from their discriminant SERS peaks, and the SERS responses exhibited a linear dependence on PAH concentrations over two orders of magnitude, with tens of nM detection limits. In addition, the HAs-Ag NPs performed well in the multicomponent analysis of PAH mixtures by the SERS technique without pre-separation.
The Analyst 01/2013; · 4.23 Impact Factor
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ABSTRACT: A disposable Ag-graphene sensor was developed for rapid and sensitive in-situ detection of polar antibiotics in water using electrophoretic preconcentration (EP) and surface-enhanced Raman spectroscopy (SERS). The Ag-graphene sensor was fabricated by depositing Ag-graphene nanocomposites synthesized through a facile one-pot method on the disposable screen-printed electrodes (SPEs) and characterized by transmission electron microscopy (TEM) and atomic force microscopy (AFM). SERS properties and detection applicability of the developed sensor were systematically investigated. It is shown that the polar antibiotics can be selectively adsorbed on the oppositely charged sensors after applying different potentials during the EP procedure, and the SERS signals of antibiotics with an effective amplification can be achieved with proper time of preconcentration. Moreover, the Ag-graphene sensor could facilitate the molecule adsorption through weak π-π interactions between graphene and antibiotics, further improving the sensitivity of SERS detection. Under the optimum EP conditions, the representative SERS spectra of a mixed solution containing four different antibiotics can be obtained within 10min, and each antibiotic is easily distinguished by its characteristic peaks with a sub-nM detection level. The results demonstrate that the proposed disposable Ag-graphene sensor based on EP-SERS can be used for rapid and sensitive in-situ detection of polar antibiotics in aqueous samples without a pre-separation step.
Biosensors & bioelectronics 12/2012; 43C:94-100. · 5.43 Impact Factor
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ABSTRACT: We present a nanoplasmonic aptasensor for adenosine triphosphate (ATP) by using single gold nanoparticles (GNPs) as probes. The specific aptamer-ATP binding induced conformational change could modulate the surface-dependent self-catalytic growth of GNPs, which enabled the detection of ATP with ultra-sensitivity and selectivity.
Chemical Communications 08/2012; 48(77):9574-6. · 6.17 Impact Factor
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ABSTRACT: Two peptide-oligonucleotide conjugates are studied using an α-hemolysin nanopore to investigate their structural properties at the single-molecule level.
Chemical Communications 07/2012; 48(70):8784-6. · 6.17 Impact Factor
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ABSTRACT: Screen-printed electrodes (SPEs), which are used as economical electrochemical substrates, have gone through significant improvements over the past few decades with respect to both their format and their printing materials. Because of their advantageous material properties, such as disposability, simplicity, and rapid responses, SPEs have been successfully utilised for the rapid in situ analysis of environmental pollutants. This critical review describes the basic fabrication principles, the configuration designs of SPEs and the hybrid analytical techniques based on SPEs. We mainly overview the electrochemical applications of SPEs in environmental analysis over the past 3 years, including the determination of organic compounds, heavy metals and gas pollutants.
Analytica chimica acta 07/2012; 734:31-44. · 4.31 Impact Factor
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ABSTRACT: A novel multi-channel electrode array sensing device was fabricated by screen-printing techniques using 96-well plate as the template. To confirm its practical value, we developed a one-step preparation of multi-walled carbon nanotubes (MWCNTs) doped electrode array by an ink containing MWCNTs, which was applied to the simultaneous detection of a variety of biological samples and environmental pollutants. Results demonstrated that the designed sensing device could carry out the multiple measurements of different analytes at the same time, while MWCNTs enhanced the electrocatalytic activity of electrodes toward electroactive molecules. The required amount of each sample was only ∼200 μL. Moreover, the excellent differential pulse voltammetric (DPV) response toward dopamine, hydroquinone and catechol was obtained and the detection limits was determined to be 0.337, 0.289 and 0.369 μM, respectively. Comparing it with the traditional screen-printed electrode (SPE), this sensing device possesses the advantages of high-throughput, fast electron transfer rate for electrodes, short-time analysis and low sample consumption.
The Analyst 05/2012; 137(14):3220-3. · 4.23 Impact Factor
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ABSTRACT: We are presenting a strategy for the fabrication of disposable screen-printed electrodes modified with mercury nano-droplets
and capable of sensing heavy metal ions. They were prepared by coating electrodes with a mixture of multi-walled carbon nanotubes
and chitosan, this followed by adsorption of mercury. The resulting sensor was characterized by cyclic voltammetry and impedance
spectroscopy. Also the effects caused by adsorption of mercury were investigated. It is shown that square wave anodic stripping
voltammetry enables simultaneous determination of cadmium(II), lead(II) and copper(II), for which detection limits of 12,
23 and 20nM, respectively, are found. Relative standard deviations for ten determinations at 0.6µM concentrations of these
ions are in the range of 3.0 to 5.7%. The applicability was tested by analyzing river water and showed recoveries between
94.1 and 104.6%, thus demonstrating its utility for in-field monitoring of these heavy metal ions.
Keywords
Heavy metal ions-Multi-walled carbon nanotubes-Chitosan-Mercury nano-droplet-Square wave anodic stripping voltammetry
Microchimica Acta 04/2012; 169(3):321-326. · 3.03 Impact Factor
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ABSTRACT: Noble metal nanoparticles have excellent optical and chemical properties and are widely used in optics, sensors, and biomedicines. The inherent characteristics of metal nanoparticles, particularly their size, play important roles in their applications. The ability to readily measure the size of single nanomaterials on-site is crucial to the rapid development of single-particle sensors. In this study, we developed a facile and real-time method for estimating the diameter of single gold nanoparticles (GNPs) that range from 35 to 110 nm in diameter; this technique uses the chrominance of the GNP's plasmon resonance scattering light that is captured by a dark-field microscope (DFM). The RGB (three primary colors, red, green, and blue) chrominance information from the dark-field image can be directly converted into the diameters of the GNPs using the relationship between the particle size and the scattering light peak wavelength; this conversion was carried out using Matlab program based on an RGB-To-Wavelength (RTW) process. This approach is more convenient, less time-consuming, and enables observation under arbitrary conditions compared to the scanning electron microscopy (SEM) technique. The differences between the diameters of the GNPs that were calculated using this method and those that were measured using SEM were less than 5 nm. The RTW method has also been applied in the monitoring of the refractive index of the media surrounding the GNPs, and their dynamic acting within cells in real-time.
Analytical Chemistry 04/2012; 84(10):4284-91. · 5.86 Impact Factor
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ABSTRACT: We demonstrate that the continuous real-time monitoring of the growth and surface oxidation process of single Cu nanoparticles (NPs) on an indium-tin oxide (ITO) substrate by dark-field microscopy (DFM) and plasmon resonance Rayleigh scattering (PRRS) spectroscopy is possible.
Chemical Communications 02/2012; 48(10):1511-3. · 6.17 Impact Factor
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Lab on a Chip 01/2012; 12(5):837-837. · 5.67 Impact Factor
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ABSTRACT: We present a nanoplasmonic aptasensor for adenosine triphosphate (ATP) by using single gold nanoparticles (GNPs) as probes. The specific aptamer-ATP binding induced conformational change could modulate the surface-dependent self-catalytic growth of GNPs, which enabled the detection of ATP with ultra-sensitivity and selectivity.
Chemical Communications. 01/2012;
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ABSTRACT: A novel facile method of fabricating disposable and highly reproducible surface-enhanced Raman spectroscopy (SERS) arrays using screen printing was explored. The screen printing ink containing silver nanoparticles was prepared and printed on supporting materials by a screen printing process to fabricate SERS arrays (6 × 10 printed spots) in large batches. The fabrication conditions, SERS performance and application of these arrays were systematically investigated, and a detection limit of 1.6 × 10(-13) M for rhodamine 6G could be achieved. Moreover, the screen printed SERS arrays exhibited high reproducibility and stability, the spot-to-spot SERS signals showed that the intensity variation was less than 10% and SERS performance could be maintained over 12 weeks. Portable high-throughput analysis of biological samples was accomplished using these disposable screen printed SERS arrays.
Lab on a Chip 12/2011; 12(5):876-81. · 5.67 Impact Factor
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Li-Xia Qin,
Yang Li, Da-Wei Li,
Chao Jing,
Bao-Qin Chen,
Wei Ma,
Arnon Heyman,
Oded Shoseyov,
Itamar Willner,
He Tian,
Yi-Tao Long
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ABSTRACT: The growth of metal nanoparticles on ion-channel pores of a stable protein 1 (SP1) membrane is monitored in situ by dark field microscopy and plasmon resonance Rayleigh scattering. In their Communication (DOI: 10.1002/anie.201106482), Y.-T. Long and co-workers describe the electrodeposition process of single nanoparticles in the core of an SP1 template and the sensing of antigen-antibody binding on single nanoparticles.
Angewandte Chemie International Edition 12/2011; · 13.45 Impact Factor
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Li-Xia Qin,
Yang Li, Da-Wei Li,
Chao Jing,
Bao-Qin Chen,
Wei Ma,
Arnon Heyman,
Oded Shoseyov,
Itamar Willner,
He Tian,
Yi-Tao Long
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ABSTRACT: Light in the dark: Metal nanoparticles (M=Ag(0) , Au(0) , or Cu(0) ) were electrodeposited onto ion-channel pores of a stable protein 1 membrane. The metal nanoparticles were implemented for detection of antigen-antibody binding events at the single-particle level using dark field microscopy and plasmon resonance Rayleigh scattering.
Angewandte Chemie International Edition 11/2011; 51(1):140-4. · 13.45 Impact Factor
