Just Published: Biosensors & Bioelectronics

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:

Biosensors & Bioelectronics
http://rss.sciencedirect.com/publication/science/5223

Selected papers from the latest issue:

Using the nanoimprint-in-metal method to prepare corrugated metal structures for plasmonic biosensors through both surface plasmon resonance and index-matching effects

25 January 2012, 01:10:19

Publication year: 2012
Source: Biosensors and Bioelectronics, Available online 24 January 2012
Chen-Chieh Yu, Kuan-Hung Ho, Hsuen-Li Chen, Shang-Yu Chuang, Shao-Chin Tseng, ...
In this study, we prepared metallic corrugated structures for use as highly sensitive plasmonic sensors. Relying on the direct nanoimprint-in-metal method, fabrication of this metallic corrugated structure was readily achieved in a single step. The metallic corrugated structures were capable of sensing both surface plasmon resonance (SPR) wavelengths and index-matching effects. The corrugated Au films exhibited high sensitivity (ca. 800 nm/RIU), comparable with or even higher than those of other reported SPR-based sensors. Because of the unique index-matching effect, refractometric sensing could also be performed by measuring the transmission intensity of the Au/substrate SPR mode—conveniently, without a spectrometer. In the last, we demonstrated the corrugated Au film was capable of sensing biomolecules, revealing the ability of the structure to be a highly sensitive biosensor

Highlights

► Metallic corrugated structure is prepared as highly sensitive plasmonic sensors ► It can sense both surface plasmon resonance wavelength and index-matching effect ► A high sensitivity of 800 nm/RIU is achieved according to resonance wavelength shift ► Besides, the linear response of resonance intensity is adopted for sensing as well ► In the last, the structure demonstrates the ability to be a sensitive biosensor

Electrical detection of Biomolecular adsorption on Sprayed Graphene Sheets

25 January 2012, 01:10:19

Publication year: 2012
Source: Biosensors and Bioelectronics, Available online 24 January 2012
Tamon R. Page, Yuhei Hayamizu, Christopher R. So, Mehmet Sarikaya
The binding affinities of graphite-binding peptides to a graphite surface were electrically characterized using sprayed graphene field effect transistors (SGFETs) fabricated with solution exfoliated graphene. The binding affinities of these peptides were also characterized using atomic force microscopy (AFM) and mechanically exfoliated graphene field effect transistors (GFETs) to confirm the validity of the SGFET platform. Binding constants obtainedviaGFET and AFM were comparable with those observed using SGFETs. The sprayed graphene film serves as a scalable platform to study biomolecular adsorption to graphitic surfaces

Highlights

► We fabricated graphene field effect transistors with solution exfoliated graphene ► The transistor enables us to characterize bio-molecular adsorption electrically ► We studied solid-binding peptides as a molecular calibration tool ► This sensor responded to the peptides comparably with conventional graphene sensors ► The sensorgrams are verified by atomic force microscopy

Evaluation of permselective membranes for optimization of intracerebral amperometric glutamate biosensors

25 January 2012, 01:10:19

Publication year: 2012
Source: Biosensors and Bioelectronics, Available online 24 January 2012
 N.Wahono, S. Qin, P. Oomen, T.I.F. Cremers, M.G. de Vries, ...
Monitoring of extracellular brain glutamate concentrations by intracerebral biosensors is a promising approach to further investigate the role of this important neurotransmitter. However, amperometric biosensors are typically hampered by Faradaic interference caused by the presence of other electroactive species in the brain, such as ascorbic acid, dopamine, and uric acid. Various permselective membranes are often used on biosensors to prevent this. In this study we evaluated the most commonly used membranes, i.e. nafion, polyphenylenediamine, polypyrrole, polyaniline, and polynaphthol using a novel silica-based platinum electrodeFirst we selected the membranes with the highest sensitivity for hydrogen peroxidein vitroand an optimal selectivity against electrochemical interferents. Then we evaluated the performances of these membranes in a short lasting (3-4 hrs)in vivoexperiment. We found that bestin vitroperformance was accomplished with biosensors that were protected by a poly(m-phenylenediamine) membrane deposited onto the platinum electrode by cyclic voltammetry. However, post-implantation evaluation of these membranes showed poor selectivity against dopamine. Combination with a previously applied nafion layer did not protect the sensors against acute biofouling; indeed it was even counter effective.Finally, we investigated the ability of our biosensors to monitor the effect of glutamate transport blocker DL-TBOA on modulating glutamate concentrations in the prefrontal cortex of anaesthetized rats. The optimized biosensors recorded a rapid 35-fold increase in extracellular glutamate, and are considered suitable for further explorationin vivo

Highlights

► Several permselective membranes were studied to improve glutamate sensorsin vivoperformance ► Poly(m-PD) CV shows highest performance to repel interfering compounds ► There is no significance biofouling effect after implantation on GluOx activity ► This sensor type has the potential to be used to monitor glutamate in brain

Simultaneous determination of ascorbic acid, dopamine and uric acid using high-performance screen-printed graphene electrode

23 January 2012, 22:13:51

Publication year: 2012
Source: Biosensors and Bioelectronics, Available online 21 January 2012
Jianfeng Ping, Jian Wu, Yixian Wang, Yibin Ying
A disposable and sensitive screen-printed electrode using an ink containing graphene was developed. This electrode combined the advantages of graphene and the disposable characteristic of electrode, which possessed wide potential window, low background current and fast electron transfer kinetics. Compared with the electrodes made from other inks, screen-printed graphene electrode (SPGNE) showed excellent electrocatalytic activity for the oxidation of ascorbic acid (AA), dopamine (DA), and uric acid (UA). Three well-defined sharp and fully resolved anodic peaks were found at the developed electrode. Differential pulse voltammetry was used to simultaneous determination of AA, DA, and UA in their ternary mixture. In the co-existence system of these three species, the linear response ranges for the determination of AA, DA, and UA were 4.0 − 4500 μM, 0.5 − 2000 μM, and 0.8 − 2500 μM, respectively. The detection limits (S/N = 3) were found to be 0.95 μM, 0.12 μM, and 0.20 μM for the determination of AA, DA, and UA, respectively. Furthermore, the SPGNE displayed high reproducibility and stability for these species determination. The feasibility of the developed electrode for real sample analysis was investigated. Results showed that the SPGNE could be used as a sensitive and selective sensor for simultaneous determination of AA, DA, and UA in biological samples, which may provide a promising alternative in routine sensing applications

Highlights

► A disposable electrode made from graphene-based screen-printing ink was proposed. ► Large potential window, low background current and fast electron transfer kinetics. ► Three well-defined and fully resolved peaks for oxidation of three species. ► High sensitivity, selectivity, stability, reproducibility and easy fabrication.

Just Published: Spectrochimica Acta Part B: Atomic Spectroscopy

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:

Spectrochimica Acta Part B: Atomic Spectroscopy
http://rss.sciencedirect.com/publication/science/5287

Selected papers from the latest issue:

Spatial emission distribution of a pulsed radiofrequency glow discharge: Influence of the pulse frequency

25 January 2012, 01:10:56

Publication year: 2012
Source: Spectrochimica Acta Part B: Atomic Spectroscopy, Available online 24 January 2012
Rebeca Valledor, Jorge Pisonero, Thomas Nelis, Nerea Bordel
A pulsed radiofrequency Glow Discharge (pulsed rf GD) plasma has been spectroscopically characterized by performing side-on measurements of the emitted radiation. The effect of varying the pulse frequency (e.g. between 100 and 10000 Hz), while keeping the duty cycle constant at 25%, has been investigated on different argon and analyte (i.e. copper) emission lines, at different plasma locations. In particular, it is observed that an intermediate frequency of 2.5 kHz favors the excitation of the argon atoms, while the argon ions are preferably excited by lower frequencies (e.g. longer pulse widths). Moreover, the excitation of copper atoms has a strong dependence on the upper energy level, and it has been noticed that the emission from higher levels is favored by the use of lower pulsed-rf frequencies. On the other hand, it has been found that the spatial distribution of the gas species and the analyte species (i.e. Ar and Cu, respectively) differ from each other: the atomic argon emission extends longer along the plasma plume than the atomic copper emission. Furthermore, ionic species have their maximum emission signal in the region close to the anode; however, their emission signal decay quite fast at increasing distances to the anode. Nevertheless, it should be highlighted that it is possible to detect ionic emission at distances far away from the negative glow; in regions where usually the sampler cone interface is placed in GD-MS instruments.

Highlights

► Influence of frequency on the spatial emission distribution of pulsed-rf-GD-OES ► Ar emission is enhanced at intermediate pulse frequencies (2-3 KHz) ► Cu emission from energetic levels is favored at low frequencies (100 Hz) ► Cu emission from lower upper levels (< 4 eV) is enhanced at high frequency (10 KHz) ► Ion Cu population around sampler cone region close related to GD conditions

Influence of nitrogen impurities on the population of plasma species in atmospheric-pressure helium microwave plasmas

25 January 2012, 01:10:56

Publication year: 2012
Source: Spectrochimica Acta Part B: Atomic Spectroscopy, Available online 24 January 2012
J. Muñoz, J. Margot, M.K. Benhacene-Boudam
The characteristics of a helium microwave plasma produced at atmospheric pressure have been studied by means of laser induced fluorescence and emission spectroscopy. The influence of nitrogen impurities on discharge parameters (electron density and gas temperature) has been studied together with the variation of the He metastable (2S and 2S) populations. A strong decrease of the He metastable densities for nitrogen concentrations as small as 1% was found. The dependence of the populations of nitrogen molecular and atomic species has been examined as a function of the electron density and nitrogen concentration in helium. Comparison with a theoretical model accounting for the presence of nitrogen in the discharge show that Penning ionization by both atomic and molecular nitrogen play an important role on the metastable quenching.

Highlights

► Influence of N2impurities (< 1%) on a He plasma was studied by FIL and OES. ► Small impact of N2impurities on electron density and gas temperature. ► A strong decrease of He metastable density upon N2introduction was found. ► Penning ionization of nitrogen produces He quenching.

The effect of sample temperature on the emission line intensification mechanisms in orthogonal double-pulse Laser Induced Breakdown Spectroscopy

25 January 2012, 01:10:56

Publication year: 2012
Source: Spectrochimica Acta Part B: Atomic Spectroscopy, Available online 24 January 2012
R. Sanginés, H. Sobral, E. Alvarez-Zauco
Orthogonal double-pulse laser ablation on aluminum-based alloy target at atmospheric pressure was investigated by time-resolved optical emission spectroscopy. Studies were performed as a function of the distance from the first pulse plasma induced in air to the sample surface. Double-pulse experimental results were compared to single-pulse laser ablation experiments carried out in a heated target to up to 500 °C. Emission lines intensification mechanisms are discussed in terms of the sample heating by the pre-ablation pulse. Crater volume was also determined via confocal microscopy for both, double pulse and target heating, experiments. It was found that the emission intensification is mainly due to an enhancement of the ablated mass. The mechanisms for the mass removal increasing are discussed.

Highlights

► Emission enhancement in orthogonal double pulse (DP) LIBS were investigated. ► DP-LIBS results were compared to single pulse LIBS onto a heated target. ► Target heating produced by the air plume contributes to DP emission intensification.

Expansion and backscattering of laser produced Fe plasma plume

25 January 2012, 01:10:56

Publication year: 2012
Source: Spectrochimica Acta Part B: Atomic Spectroscopy, Available online 24 January 2012
M. Bišćan, S. Milošević
Forward and backward moving atoms within the laser produced plasma plume were studied by means of a cavity ringdown spectroscopy. The plume was produced using a nanosecond Nd-YAG laser pulse illuminating stainless steel target in a vacuum or helium background gas. Measurements were done at pressures ranging from 10to 1 mbar. Atomic absorption line shapes of iron around 388 nm were measured above and below the target at different times after the ablation initiation. Changes in absorption line shapes were used to estimate kinetic parameters of the plasma plume. The observations were interpreted through modeling which takes into account the angular and velocity distributions of atoms in the expanding plume. The amount of backward scattered atoms was about 10% of the total number of particels.

Highlights

► Fe absorption line shapes in laser ablation using CRDS. ► Measurement at different distances from the target and different helium pressures. ► The expansion can be described using a simple model. ► Backscattering occurs at the beginning of cloud expansion just above the target. ► 10% of particles backscattered at 10mbar.

Now an Environmentally Friendly Ductless Fume Hood

Air Science has introduced its NEW Purair ECO™ line of Energy-Saving Ductless Fume Hoods designed for both chemical and particulate protection over a broad range of laboratory and industrial applications.

Development of the Purair ECO is in response to an increasing worldwide demand for safe, cost-effective and energy-efficient ductless containment cabinets that minimize stress on facility HVAC systems without compromising protection for personnel and the environment.

The Purair ECO is available with a choice of controllers including the company’s new ECOair™ touchpad control with color display interface.

An optional BACnet network interface connects all cabinet control, monitoring and alarm functions to an open-source facility monitoring system. The system is based on an industry-wide, non-proprietary ASHRAE compliant protocol for green building management.

The Purair ECO is available in five standard sizes from 30" wide to 69" wide.

For complete detail and specifications on the NEW ECO™ Energy-Saving Ductless Fume Hoods, call, visit the website, or email Air Science.

Air Science USAPO Box 62296
Fort Myers, Florida 33906 USA

Toll Free: 800-306-0656
Phone: 239-489-0024
Fax: 800-306-0677

E-mail: info@airscience.com
Web: http://www.airscience.com/

Unlocking the potential of Stem Cells in Neuroscience Research

AMSBIO has written an informative technical article to enable neuroscience researchers to learn more about a new method to control and direct differentiation of physiologically relevant neural cell types using stem cell qualified reagents.

Stem cells have revolutionized our approaches to and understanding of neuroscience. The key to research success is the ability to control and direct differentiation into physiologically relevant neural cell types.

Controlling cell differentiation in a predictable way is a major challenge in stem cell research. The new method described within the article shows how to differentiate adult neural stem cells and pluripotent ES cells using 3D extracellular matrices and reagents from AMSBIO, enabling researchers to gain a valuable insight into the stem cells they are studying.

For a copy of the article please visit www.amsbio.com/news/whitepaper/Stem_Cells_in_Neuroscience_Research.pdf  or contact the company on +44-1235-828200 / +1-949-768-8365, email info@amsbio.com or www.amsbio.com/brochures/Neuroscience_Tools_AMSBIO.pdf  for further information.

AirClean® Systems, a world leader in ductless fume hood technology, also offers AirMax™ polypropylene total exhaust fume hoods

The AirMax fume hood with Wet Fume Scrubber system is a complete solution for protecting personel from dangerous chemical exposure while also protecting ductwork and the environment by scrubbing acids and other water soluble gases from fume hood exhaust.

AirMax hoods are constructed of thermoplastics (primarily polypropylene) with all contact surfaces utilizing seamless, thermally-welded joints. This eliminates the potential for corrosion commonly associated with metal fume hoods. The advanced rolled-entry airfoil design prevents reverse flow and eddy currents, while an extended rear baffle effectively removes any heavy gases or evaporation from a spill. Dual-wall design provides ample room for mounting fixtures and services.

The Wet Fume Scrubber system is direct-mounted to the fume hood exhaust, eliminating contaminated ductwork between the fume hood and scrubber. An observation window is provided for media inspection, and the scrubber holding tank with recirculating pump is housed in the included base cabinet.

Typical applications of the AirMax with Wet Fume Scrubber are trace metal analysis, hot acid etching, acid digestions and other high-volume, high-acidity processes.

An optional spray bar for perchloric acid use is available, as is an auto pH dosing system for the holding tank.

AirMax fume hoods are available in 36”, 48”, 60”, 72” and 96” widths and are made in the USA.

For more information on AirMax total exhaust fume hoods, visit http://www.aircleansystems.com/totalexhaust_flame.htm

Near Infrared Analysis of Tablets Containing Two Active Ingredients

FOSS NIRSystems, Inc. is pleased to announce that a new NIR article has been published on the subject: Near Infrared Analysis of Tablets Containing Two Active Ingredients.

This study evaluates Near-Infrared (NIR) analysis of tablets nominally containing 4 mg of chlorpheniramine maleate (CPM) and 10 mg of phenylephrine hydrochloride (PE-HCl) per dose. The data showed promising results that could relieve laboratory workload and bring analysis closer to real time for process monitoring. Ten tablets could be analyzed in less than 3 min. The NIR assay for the determination of tablets' CU is a fast and accurate means of monitoring tablets that could be used for production and is consistent with FDA's PAT initiative.

For more information about this article, please contact Applications Scientist Robert Mattes at

rmattes@foss-nirsystems.com

New release of Enrofloxacin and Ciprofloxacin ELISA kits

Enrofloxacin and ciprofloxacin are members of the newer fluoroquinolone antibiotics. Enrofloxacin/Ciprofloxacin ELISA kits are now available from Randox Food Diagnostics for the detection of growth promoting compounds within food producing animals. Using a simple methanol extraction Randox can achieve an LOD of <0.6ppb.

Benefits include:

• Breakable well format
• Reduced ELISA incubation time resulting in reduced overall assay time -50 minutes
• No special storage requirements at -20oC
• Reagents ready to use apart from wash buffer
• No expensive solvents or equipment required.
• Excellent shelf life of 2 years
• Excellent limit of detection
• Spiking material available (1000ng/ml)

Please visit our website for more information: http://www.randoxfooddiagnostics.com/ or email enquiries@randoxfooddiagnostics.com

Company Profile:

Randox Food Diagnostics is an associate of Randox Laboratories who have 30 years experience in the diagnostic market and a devoted research and development team. We provide a range of excellent tools for screening for antimicrobials, growth promoting hormones and drugs of abuse in animals and foodstuffs, as well as our dedicated testing kits for the wine and beverage markets.  Randox Food Diagnostics offer excellent limit of detections and simple sample preparations. Our portfolio includes 28 ELISA’s and 8 multiplex screening platforms spanning over 100 separate tests. All products are manufactured at our state-of-the-art ISO 13485 accredited manufacturing plant in the UK.