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World Congress on Biosensors 2014

World Congress on Biosensors 2014
Biosensors 2014

Wednesday, 20 November 2013

Just Published: Sensors & Actuators B: Chemical

A new issue of this journal has just been published. To see abstracts of the papers it contains (with links through to the full papers) click here:

Selected papers from the latest issue:

A novel way for detection of eugenol via poly (diallyldimethylammonium chloride) functionalized graphene-MoS2 nano-flower fabricated electrochemical sensor

20 November 2013, 08:11:22
Publication date: 1 March 2014
Source:Sensors and Actuators B: Chemical, Volume 192
Author(s): Qingliang Feng , Kaiyue Duan , Xiaoliang Ye , Daban Lu , Yongling Du , Chunming Wang
Poly (diallyldimethylammonium chloride) functionalized graphene-MoS2 nano-flower materials (PDDA-G-MoS2) were successfully synthesized, in which the addition of MoS2 wrinkling the graphene further increased the specific surface area. Then, the gold nanoparticles (AuNPs) were assembled on the surface of PDDA-G-MoS2 via electrostatic attractive force and function of AuS bond. The obtained Au/PDDA-G-MoS2 nanomaterial was used to modify glassy carbon electrode (Au/PDDA-G-MoS2/GCE) and determine sensitively eugenol. The oxidation peak currents increased distinctly on the proposed electrochemical sensor by cyclic voltammetry (CV) in 0.10molL−1 NaAc-HAc buffer solution (pH=5.50), indicating that the material shows excellent electrochemical properties. The reaction kinetics was studied and the experimental conditions were optimized. The oxidation peak current of eugenol increased linearly with addition of concentration in the range from 0.1 to 440μmolL−1 with a low detection limit of 0.036μmolL−1 (S/N =3). This sensor exhibited high sensitivity, good stability and fast responses, and also has been applied to determination of eugenol in real samples with satisfactory results. The novel PDDA functionalization graphene-MoS2 nanoflower shows excellent electrocatalysis for determination of eugenol and satisfactory dispersity in water than graphene; these would show its potential application in analysis, medical science and nanodevice field via combining graphene with graphene-like materials (MoS2) for its novel properties.

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Dual signaling of azide ions by deprotection of a dichlorofluorescein chloroacetate

20 November 2013, 08:11:22
Publication date: 1 March 2014
Source:Sensors and Actuators B: Chemical, Volume 192
Author(s): Jung Woo Lee , Ho Won Kim , Hyun Gyu Im , Hong Yeong Kim , Suk-Kyu Chang
We investigated the dual optical signaling of azide ions by the selective cleavage of fluorescein acetates. The chloroacetate derivative of 2′,7′-dichlorofluorescein showed prominent colorimetric and fluorogenic signaling behaviors toward azide ions in aqueous acetonitrile solution. Fluorescein analogs also showed a selective response, but the signaling speed was unfavorably slow. The detection of azide ions was not affected by the presence of commonly encountered anions. In particular, significant interference from sulfide ions in the azide-selective signaling of the probe was readily suppressed by using a Hg(II)–N,N,N′,N′-tetrakis(2-pyridylmethyl)ethylenediamine (TPEN) complex as a masking agent. The detection limit for the determination of azide ions by the chloroacetate of 2′,7′-dichlorofluorescein in 10% aqueous acetonitrile was 4.0×10−7 M (17ppb). The signaling of azide ions in real samples using tap water and simulated wastewater was also tested.

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Characterization of a new fluorescence-enhancing substrate for microarrays with femtomolar sensitivity

20 November 2013, 08:11:22
Publication date: 1 March 2014
Source:Sensors and Actuators B: Chemical, Volume 192
Author(s): Marina Cretich , Clelia Galati , Lucio Renna , Guglielmo Guido Condorelli , Paola Gagni , Marcella Chiari
The demand for high sensitivity in microarray technology has stimulated the research of new labeling strategies, new substrates with increased loading capacity and new approaches to amplify the fluorescence signals. Although these methods improve the sensitivity, they are based on non-routine procedures which limit their widespread usage. A simple way to achieve fluorescence enhancement is the optical interference (OI) coating technology based on the use of substrates with films of well-defined thickness that maximize photoabsorption of the dye molecules in the vicinity of the surface and reflect the emitted light toward the detector. Here we introduce a new substrate for fluorescence enhancement composed of a thin aluminum mirror and a single quarter wave silicon oxide as a dielectric layer. The use of such material allows the development of a substrate suited for parallel production in conventional IC (Integrated Circuit's) technology, which produces a 20-fold enhancement of fluorescence compared to glass, which is the most common material used in microarrays. The new substrate was coated with a copolymer of N,N-dimethylacrylamide, N-acryloyloxysuccinimide, and 3-(trimethoxysilyl)propyl methacrylate, copoly(DMA-NAS-MAPS), which forms, by a simple and robust procedure, a functional nanometric film that covalently binds bio-probes on the surface and efficiently suppresses non-specific adsorption. The performance of the new fluorescence-enhancing substrate in microarray technology was demonstrated for the detection of a panel of inflammation biomarkers pushing detection limits into the femtomolar range.

Measurement of the evolution of rigid and viscoelastic mass contributions from fibrin network formation during plasma coagulation using quartz crystal microbalance

20 November 2013, 08:11:22
Publication date: 1 March 2014
Source:Sensors and Actuators B: Chemical, Volume 192
Author(s): Ramji S. Lakshmanan , Vitaly Efremov , Sinéad M. Cullen , Anthony J. Killard
The coagulation of blood plasma and the effect of fibrinogen concentration were studied with a quartz crystal microbalance (QCM), where frequency and half-width at half-maximum (bandwidth) values measured from the conductance spectrum near resonant frequency were used. Bandwidth change is an indicator of energy dissipation, allowing for an understanding of qualitative changes occurring during fibrin clot formation. Both frequency shift (Δf) and bandwidth shift (ΔΓ) were dependent on the concentration of fibrinogen in plasma. We defined a sum of squares function α (=Δf 2/1000+ΔΓ 2/1000) that measures absolute changes in QCM resonant characteristics to semi-quantitatively include an overall contribution of adsorbed mass and elastic modulus components and a function β (=1−ΔΓ/Δf) that indicates qualitatively the nature of response based on its deviation from ideal Newtonian behaviour. Increasing concentration of fibrinogen resulted in an increase in the value of α, showing that a larger amount of fibrinogen results in larger amount of coupled viscoelastic mass. Changes in β indicated that the nature of changes occurring was very similar to Newtonian and that coupling of rigid-mass dominates the overall response in the early stage of coagulation and in the later stage growing elastic mass compensates some of the response.

A novel BODIPY-based colorimetric and fluorometric dual-mode chemosensor for Hg2+ and Cu2+

20 November 2013, 08:11:22
Publication date: 1 March 2014
Source:Sensors and Actuators B: Chemical, Volume 192
Author(s): Xingxing He , Jing Zhang , Xungao Liu , Lin Dong , Di Li , Huayu Qiu , Shouchun Yin
A novel BODIPY-based colorimetric fluorescent sensor with bis[2-(phenylseleno)ethyl]amine as binding site (Se-1) for Hg2+ and Cu2+ has been developed. Se-1 shows high selectivity and sensitivity toward Hg2+ and Cu2+ over alkali and transition metal ions. Se-1shows a significant red-shift in the absorption spectra from 525 to 571nm for Hg2+ and 590nm for Cu2+, which induces color changes from pink to purple and blue. Upon excitation at 570nm, Se-1 upon interaction with Hg2+ ions displays a 5-fold fluorescence enhancement with a 2nm blue-shift, while Se-1 with Cu2+ exhibits a 13-fold fluorescence enhancement and red-shifts from 595 to 610nm. The binding mode of Se-1 with Hg2+ or Cu2+ has been investigated by Job's plot, ESI and 1H NMR experiments. The absorption and fluorescence of the Se-1–Hg2+ complex can be reversibly restored to that of the uncomplexed ligand by using EDTA or cysteine, however, the sensing processing of Se-1 in response to Cu2+ ions cannot.

A microfluidic device for the hydrodynamic immobilisation of living fission yeast cells for super-resolution imaging

20 November 2013, 08:11:22
Publication date: 1 March 2014
Source:Sensors and Actuators B: Chemical, Volume 192
Author(s): Laurence Bell , Ashwin Seshia , David Lando , Ernest Laue , Matthieu Palayret , Steven F. Lee , David Klenerman
We describe a microfluidic device designed specifically for the reversible immobilisation of Schizosaccharomyces pombe (Fission Yeast) cells to facilitate live cell super-resolution microscopy. Photo-Activation Localisation Microscopy (PALM) is used to create detailed super-resolution images within living cells with a modal accuracy of >25nm in the lateral dimensions. The novel flow design captures and holds cells in a well-defined array with minimal effect on the normal growth kinetics. Cells are held over several hours and can continue to grow and divide within the device during fluorescence imaging.

Synthesis of Ag-MoS2/chitosan nanocomposite and its application for catalytic oxidation of tryptophan

20 November 2013, 08:11:22
Publication date: 1 March 2014
Source:Sensors and Actuators B: Chemical, Volume 192
Author(s): Xiaohong Xia , Zhixiang Zheng , Yan Zhang , Xiaojuan Zhao , Chunming Wang
A convenient and low-cost synthesis approach is proposed for the development of a simple and novel electrochemical sensor for the determination of tryptophan (Try). In this synthesis process, graphene-like molybdenum sulfide was successfully obtained, and silver nanoflakes (AgNFs) were directly synthesized on the surface of molybdenum sulfide (MoS2) films, in this process chitosan (CS) and ascorbic acid (AA) acted as the stabilizer and reducing agent, respectively. This nanocomposite was characterized by transmission electron microscopy (TEM) and X-ray diffraction (XRD). Electrochemical impedance spectroscopy (EIS), cyclic voltammetry (CV) and differential pulse voltammetry (DPV) were employed to evaluate the electrochemical property of Ag-MoS2/CS toward the oxidation of tryptophan. Under the optimized experimental conditions, the oxidation peak currents are proportional to the concentrations of tryptophan over the range of 0.5μM to 120μM, and the detection limit is 0.05μM (S/N=3). Moreover, the proposed method is free of interference from other amino acid to other coexisting species.

Polymeric optodes based on upconverting nanorods for fluorescence measurements of Pb2+ in complex samples

20 November 2013, 08:11:22
Publication date: 1 March 2014
Source:Sensors and Actuators B: Chemical, Volume 192
Author(s): Jing Wu , Yu Qin
We reported here a lead ion selective optode incorporating NaYF4: Er,Yb upconverting nanorods, chromoionophore ETH 5418, and lead ionophore together in hydrophobic polymer matrixes. The absorption spectra of protonated and unprotonated ETH 5418 overlap the two emission peaks of the upconverting material, respectively, which allows the fluorescent ion sensing based on the inner filter effect. The proposed optodes exhibited highly selective and reproducible sensing property for measuring lead ions in the range of 10−6–10−2 M at pH 5. Because the excitation source is 980nm and the emission wavelength lies in the near-infrared region, the sensors have been successfully used in complex samples for example plasma with minimized background absorption and sample autofluorescence. The lead levels in sheep plasma and artificial industry wastewater samples obtained by the optode were comparable with the known addition amounts of Pb(NO3)2, providing a new method for testing Pb2+ in the industry wastewater.

GADH screen-printed biosensor for gluconic acid determination in wine samples

20 November 2013, 08:11:22
Publication date: 1 March 2014
Source:Sensors and Actuators B: Chemical, Volume 192
Author(s): Lorena del Torno-de Román , M. Asunción Alonso-Lomillo , Olga Domínguez-Renedo , Arrate Jaureguibeitia , M. Julia Arcos-Martínez
Gluconate dehydrogenase (GADH) biosensors have been developed for the satisfactory determination of gluconic acid in wine samples, without any pretreatment. The biosensors have been fabricated by cross-linking immobilization of GADH onto screen-printed carbon electrodes, containing the mediator tetrathiafulvalene (TTF). Chronoamperograms have been registered at +100mV vs. screen-printed Ag/AgCl electrode by successive additions of a gluconic acid solution in the concentration range from 9.0 to 131.4μM. This method shows a reproducibility of 8.1% (n =3) related to the slopes of these calibration curves and a repeatability of 3.2% (n =5). The procedure has shown an average capability of detection of 9.0μM for a probability of false positive and negative of 0.05. Wine samples have been analyzed with these biosensors, obtaining satisfactory results.

Volume-doped cobalt titanates for ethanol sensing: An impedance and X-ray absorption spectroscopy study

20 November 2013, 08:11:22
Publication date: 1 March 2014
Source:Sensors and Actuators B: Chemical, Volume 192
Author(s): Clemens J. Belle , Günter E. Wesch , Stefan Neumeier , M. Janeth Lozano-Rodríguez , Andreas C. Scheinost , Ulrich Simon
The dynamic C2H5OH sensitivity of ilmenite-type cobalt titanates volume-doped by 2at% Li, Na, K, Sb, La, Sm, Gd, Ho and Pb was systematically studied with respect to exhaust monitoring. Therefore, the p-type semiconducting CoTiO3 materials were characterized as resistive gas sensors via high-throughput impedance spectroscopy toward 5–200ppm C2H5OH at 300–500°C. The best performing materials were tested further by time-resolved and long-term measurements whereby the CoTiO3 volume-doped with K exhibited an outstanding overall performance. X-ray absorption spectroscopy on this particular material gave evidence that the local structure around Co and Ti remains unaffected by the doping despite of a slight increase in static disorder. Hence, the effect of K doping does not originate from alteration in the metal-to-oxygen interaction as expected from previous findings.

Validation of wavelength modulation spectroscopy techniques for oxygen concentration measurement

20 November 2013, 08:11:22
Publication date: 1 March 2014
Source:Sensors and Actuators B: Chemical, Volume 192
Author(s): S. Neethu , R. Verma , S.S. Kamble , J.K. Radhakrishnan , P.P. Krishnapur , V.C. Padaki
Tunable Diode Laser Absorption Spectroscopy (TDLAS) based gas sensing technology, has widespread applications, ranging from use in biomedical industry to aerospace applications. An experimental set-up was established to measure concentration of oxygen gas in the range 0–100% using TDLAS technique. The oxygen absorption at 760.241nm was scanned with a tunable DFB laser, and wavelength modulation spectroscopy was used to obtain the harmonics (1f, 2f, 3f & 4f) of the oxygen absorption signal. The modulation parameters such as the modulation voltage, modulation frequency, reference phase, time constant of lock in amplifier, the tuning voltage, and the tuning frequency were optimized to obtain the harmonics of high amplitude and narrow half width. Keeping the experimental parameters constant, the oxygen concentration measurements were obtained by the following three methodologies, viz, (i) using only the 2nd harmonic, (ii) using the 2nd and 4th harmonics and, (iii) using the 1st and 2nd harmonics. The results of these measurements were compared and the merits and drawbacks of these methods are discussed.

Colorimetric determination of DNA concentration and mismatches using hybridization-mediated growth of gold nanoparticle probes

20 November 2013, 08:11:22
Publication date: 1 March 2014
Source:Sensors and Actuators B: Chemical, Volume 192
Author(s): Wei-Feng Fang , Wen-Jone Chen , Jing-Tang Yang
A novel colorimetric approach to sense DNA samples was demonstrated successfully based on a concept of hybridization-mediated growth of gold nanoparticles probes (AuNP probes). The growth size and conformation of the probes are dominated by DNA samples that hybridize with the probes. The growth probes serve as nanoparticle biosensors that can be utilized to analyze concentrations of DNA samples or to discriminate mismatches of DNA samples to the probes (complementarity of DNA) in terms of size- and shape-dependence optical properties. By means of the proposed method, not only the semi-quantitation of target DNA but also the differentiation of DNA mismatches can be readily achieved with a naked eye or simple spectrophotometer. This method features small consumption of reagents, a satisfactory detection limit (about 60nM), a small duration of assay (a couple of minutes), and a simple procedure without thermal control. 

1 comment:

  1. "The oxidation peak currents increased distinctly on the proposed electrochemical sensor by cyclic voltammetry (CV) in 0.10molL-1 NaAc-HAc buffer solution (pH = 5.50), indicating that the material" Also, these sensors can find intermediate results of oxidation (chemical market research)

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