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World Congress on Biosensors 2014

World Congress on Biosensors 2014
Biosensors 2014

Wednesday, 29 February 2012

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:

Enhanced response characteristics of SnO2thin film based sensors loaded with Pd clusters for methane detection

29 February 2012, 02:16:20Go to full article
Publication year: 2012
Source: Sensors and Actuators B: Chemical, Available online 28 February 2012
Divya Haridas, Vinay Gupta
This paper reports the response characteristics of rf-sputtered SnO2thin films (90 nm thin) loaded with nanoscale catalytic clusters for detection of methane. Ultrathin (8 nm) metal and metal-oxide catalysts (Pt, Ag, Ni, Pd, Au, NiO, Au2O3) clusters are loaded over the surface of SnO2thin film. The SnO2-Pd cluster structure is found to exhibit an enhanced response (97.2%) for 200 ppm of methane at a relatively low operating temperature (220 °C). The enhanced response is shown to be primarily due to the dominant roles played by both Fermi level energy control mechanism and spillover mechanism. Thickness of the Pd catalyst clusters in the nano-scale range (2 to 20 nm), influences significantly the sensor characteristics. Optimized performance is observed with 10 nm thick Pd catalyst clusters showing a high response (∼99.2%) at a relatively low operating temperature of 160 °C. Thickness of the Pd clusters is shown to influence the amount of adsorbed oxygen present on the uncovered SnO2film surface and also activates the spillover mechanism. The results suggest the possibility of utilizing the sensor structure having novel dispersal of Pd catalyst clusters (10 nm thickness) on the surface of SnO2thin film for efficient detection of methane gas.

Polymer-assisted synthesis of metallopolymer nanocomposites and their applications in liquefied petroleum gas sensing at room temperature

29 February 2012, 02:16:20Go to full article
Publication year: 2012
Source: Sensors and Actuators B: Chemical, Available online 28 February 2012
Satyendra Singh, B.C. Yadav, Poonam Tandon, Mridula Singh, Anuj Shukla, ...
In this paper, the synthesis of the acrylamide complex of Co (II) nitrate followed by polymerization and formation of a polymer composite with inclusions of Co nanoparticles stabilized by the polymer matrix has been reported. Cobalt polyacrylamide (Co/PAAM) was prepared by the procedure including formation of cobalt acrylamide complex, followed by frontal polymerization and pyrolysis of the polymer. Structural investigations of the materials were carried out by X-ray diffractometer. Surface morphologies were analysed using scanning electron microscope and nano-structural properties were studied by using high resolution transmission electron microscope and atomic force microscope. Phase transformation temperature was evaluated using a differential scanning calorimeter. The crystallite size of the Co/PAAM was found ∼ 6 nm and confirmed by TEM analysis. Thick films of the metallopolymers were made by screen printing technique and these were investigated with exposition of LPG for measurements of LPG sensing characteristics. Larger variations in resistance were found for Co/PAAM in comparison to Co(NO3)2.(AAM)4.2H2O. The maximum values of the sensitivities were 2.9 and 23.6 MΩ/sec for Co(NO3)2.(AAM)4.2H2O and Co/polyacrylamide respectively. The reproducibility of the sensor made of Co/PAAM film was found to be 96% after one month of observations, which shows the stability and reliability of the fabricated sensor

Scaling laws and performance improvements of integrated biosensor microarrays with multi-pixel per spot

29 February 2012, 02:16:20Go to full article
Publication year: 2012
Source: Sensors and Actuators B: Chemical, Available online 28 February 2012
N. Couniot, A. Afzalian, D. Flandre
Multiplexed, real-time and low cost detection of bioanalytes can be achieved by building integrated biosensor microarrays. The lack of design guidelines for this kind of biochip leads to inferior results compared to individual biosensors. In this paper, we thoroughly study the impact of considering several pixels per spot on the performances of integrated biosensor microarrays. By taking into account the biological shot noise and electrical characteristics of the transducer, we theoretically calculate how dividing each spot into several pixels improves the limit of detection and the resolution of the overall biosensor microarray without degrading the signal-to-noise ratio. More particularly, we show that the improvement of the limit of detection depends on the individual biosensor performance while the resolution is enhanced proportionally to the square root of number of pixels per spot. Performance trade-offs, CMOS compatibility and numerical results for optical, field-effect and capacitive biosensor microarrays having multiple pixels per spot are finally established.

Leading Genomic Service Provider Selects Fluidigm Access Array Sample Prep Technology

MOgene, LC, a leading genomics service provider located in St. Louis, is implementing Fluidigm Access Array™ sample preparation technology for its targeted resequencing customers. The Access Array System is the only system that prepares amplicons for resequencing without the need for any additional library preparation while providing the lowest running costs in the industry and the flexibility to operate with any next-generation sequencer on the market.

"We purchased a Fluidigm Access Array System to provide high-throughput target enrichment for all major sequencing equipment," said Shaukat Rangwala, vice president, MOgene, LC. "Since 2004, MOgene has been involved with numerous sequencing projects such as transcriptomes, metagenomics and notably sequencing the oil palm genome as a member of the consortium working with Washington University and Orion Genomics. We believe adding the Access Array's capabilities will be a great addition to our sequencing offerings," Rangwala concluded.

"For almost a decade, MOgene has been providing genomics services to the pharmaceutical, biotech, academic, and government markets. We are extremely excited to have them incorporate the Fluidigm Access Array technology into their service portfolio. MOgene's focus on providing their customers with high quality genomics solutions based on industry leading technology has been a hallmark of their success in the market," said Gajus Worthington, Fluidigm president and chief executive officer.

MOgene is a leading global genomics service provider located in St. Louis, Missouri. MOgene offers a full range of genomic services from RNA/DNA isolation, microarrays, real-time PCR, NGS to complete analysis. Since 2004, the company has been involved with numerous sequencing projects such as transcriptomes, metagenomics and notably sequencing the oil palm genome as a member of the consortium with Washington University and Orion Genomics. MOgene recently purchased Fluidigm Access Array System to provide high-throughput target enrichment for all major sequencing instruments. MOgene also upgraded its 454 to FLX plus generating even longer reads. MOgene has demonstrated achieving a billion bases in a shotgun run. The company is a long time Agilent-certified service provider for gene expression, CGH, ChIP, miRNA and methylation microarrays. In the area of bioinformatics, the company works with its customers to provide customized solutions and publication-ready analysis. For more information, visit http://mogene.com/

Lloyd Instruments UK And Ireland Service And Support Further Strengthened

Lloyd Instruments, a world-renowned manufacturer of materials testing machines and part of AMETEK Inc., has further strengthened its service and support team in the UK and Ireland with the addition of two further regional Service Engineers. As part of a financially sound, leading global manufacturer of electronic instruments and electromechanical devices that enjoys annual sales of $3 billion and a 1200-strong workforce in the UK, Lloyd Instruments UK customer support structure has never been stronger.

The new Service Engineers bring over 20 years combined experience in electronics engineering support to the Lloyd Instruments regional Service team. Fast service response across the UK and Ireland is backed by an in-house technical support team which includes Jason Pearce, an engineer with more than 25 years service at Lloyd Instruments. All UK service engineers are UKAS (United Kingdom Accreditation Service) accredited. 

Lloyd Instruments in-house calibration laboratory has also been UKAS accredited for more than 20 years, offering UKAS approved verification and calibration of force measuring systems in tension and compression, including verification of machines from other manufacturers. The laboratory has issued more than 25,000 UKAS accredited (or their equivalent) calibration certificates to UK customers alone. The calibration laboratory is also accredited to ISO 17025-2005.

Customers are fully covered with traceable UKAS certificates from installation of the machine through the length of its life. Installation and training is carried out at the customer's premises and a UKAS certificate issued. At the end of the warranty period customers are contacted concerning machine recalibration and the type of service contract required.

Strong service and technical support is not restricted to the UK and Ireland. The service and support team based in France extends to N. Africa, while in Germany, a similar team provides support across 
Germany, Austria and Switzerland. 

The service department in Denmark is also certified to perform traceable calibration according to UKAS, and AMETEK S.A.S., sister company of Lloyd Instruments in France, is COFRAC accredited (Accreditation N1-0884). COFRAC and UKAS are members of EA  (European cooperation for Accreditation) which is recognized by all European countries as well as all over the World. There is a similar story in other regions. With an international network of distributors offering technical and service support, Lloyd Instruments continues to offer accredited facilities at locations throughout the world. 

Tuesday, 28 February 2012

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:
Selected papers from the latest issue:

An Enzymatic Immunoassay Microfluidics Integrated with Membrane Valves for Microsphere Retention and Reagent Mixing

25 February 2012, 21:52:54Go to full article
Publication year: 2012
Source: Biosensors and Bioelectronics, Available online 25 February 2012
Li Ren, Jian-Chun Wang, Wenming Liu, Qin Tu, Rui Liu, ...
The present study presents a new microfluidic device integrated with pneumatic microvalves and a membrane mixer for enzyme-based immunoassay of acute myocardial infarction biomarkers, namely, myoglobin, and heart-type fatty acid binding protein (H-FABP). Superparamagnetic microspheres with carboxyl groups on their surfaces were used as antibody solid carriers. A membrane mixer consisting of four ψ-type membrane valves was assembled under the reaction chamber for on-chip performing microsphere trapping and reagent mixing. The entire immunoassay process, including microsphere capture, reagent input, mixing, and subsequent reaction, was accomplished on the device either automatically or manually. The post-reaction substrate resultant was analyzed using a microplate reader. The results show that the average absorbance value is correlated with the concentration of cardiac markers, in agreement with the results obtained using a conventional microsphere-based immunoassay; this indicated that the proposed on-chip immunoassay protocol could be used to detect both myoglobin and H-FABP. The minimum detectable concentration is 5 ng/mL for myoglobin and 1 ng/mL for H-FABP.

Highlights

► A new and integrated microfluidics for microsphere-based enzymatic immunoassay was described. ► Microsphere retention and reagent mixing were realized via membrane microvalves and a mixer. ► The entire immunoassay process could be accomplished either automatically or manually. ► Two acute myocardial infarction-related early biomarkers were analyzed as case studies.

Label-free reflectometric interference microchip biosensor based on nanoporous alumina for detection of circulating tumour cells

25 February 2012, 21:52:54Go to full article
Publication year: 2012
Source: Biosensors and Bioelectronics, Available online 25 February 2012
Tushar Kumeria, Mahaveer D. Kurkuri, Kerrilyn R. Diener, Luke Parkinson, Dusan Losic
In this report, a label-free reflectometric interference spectroscopy (RIfS) based microchip biosensor for the detection of circulating tumour cells (CTCs) is demonstrated. Highly ordered nanoporous anodic aluminium oxide (AAO) fabricated by electrochemical anodization of aluminium foil was used as the RIfS sensing platform. Biotinylated anti-EpCAM antibody that specifically binds to human cancer cells of epithelial origin such as pancreatic cancer cells (PANC-1) was covalently attached to the AAO surface through multiple surface functionalization steps. Whole blood or phosphate buffer saline spiked with low numbers of pancreatic cancer cells were successfully detected by specially designed microfluidic device incorporating an AAO RIfS sensor, without labour intensive fluorescence labelling and/or pre-enhancement process. Our results show that the developed device is capable of selectively detecting of cancer cells, within a concentrations range of 1,000 to 100,000 cells/mL, with a detection limit of < 1000 cells/mL, a response time of <5 minutes and sample volume of 50 μL of. The presented RIfS method shows considerable promise for translation to a rapid and cost-effective point-of-care diagnostic device for the detection of CTCs in patients with metastatic cancer.

Highlights

► We develop a label-free reflectometric interference spectroscopy (RIfS) microchip biosensor for the detection of circulating tumour cells (CTCs) ► A nanoporous alumina functionlized with biotinylated human anti-EpCAM antibodies is used as a sensing platform ► The measurement of CTCs with concentrations of 1,000 to 200,000 cells/mL in buffer and whole blood is demonstrated. ► The device is highly selective to CTCs, has response time of <5 minutes and requires less than 50 μL of sample.

TiO2/MWNTs Nanocomposites-Based Electrochemical Strategy for Label-Free Assay of Casein Kinase II Activity and Inhibition

25 February 2012, 21:52:54Go to full article
Publication year: 2012
Source: Biosensors and Bioelectronics, Available online 25 February 2012
Xiaoxiao He, Zhifeng Chen, Yonghong Wang, Kemin Wang, Jing Su, ...
In this paper, a novel label-free electrochemical strategy has been developed for assay of casein kinase II (CK2) activity and inhibition using TiO2/MWNTs nanocomposites. This detection system takes advantage of specific binding of the phosphate groups with TiO2nanoparticles and fast electron transfer rate of MWNTs. In this strategy, the synthesized TiO2/MWNTs nanocomposite was firstly deposited on the surface of a glassy carbon electrode (GCE). The presence of MWNTs not only increased the surface area of the electrode but also promoted electron-transfer reaction. In the presence of CK2, the kinase reaction resulted in the phosphorylation of peptide substrates. The phosphorylated peptides were subsequently captured to the surface of GCE modified with TiO2/MWNTs nanocomposite through specific binding of the phosphate groups with TiO2nanoparticles. Then the access of redox probe [Fe(CN)6]to electrode surface was blocked. As a result, the decrease peak currents were related to the concentrations of the CK2, providing a sensing mechanism for monitoring peptides phosphorylation. The electrochemical strategy can be employed to assay CK2 activity with a low detection limit of 0.07 U/mL. The linear range of the assay for CK2 was 0 U/mL to 0.5 U/mL. Furthermore, the interferences experiments of PKA and inhibition of CK2 have been also studied by using this strategy.

Highlights

► We develop a label-free electrochemical strategy for assay of CK2 and inhibition. ► The electrochemical assay is based on TiO2/MWNTs nanocomposites. ► Specific binding of the phosphate groups with TiO2nanoparticles. ► Fast electron transfer rate of MWNTs. ► Providing a general platform for monitoring the activity of other kinases.

A novel approach to determining the affinity of protein-carbohydrate interactions employing adherent cancer cells grown on a biosensor surface

25 February 2012, 21:52:54Go to full article
Publication year: 2012
Source: Biosensors and Bioelectronics, Available online 25 February 2012
Diluka Peiris, Anatoliy Markiv, G. Paul Curley, Miriam V. Dwek
The development of biological agents for the treatment of solid tumours is an area of considerable activity. We are pursuing carbohydrate-binding proteins (lectins) in a strategy aimed at targeting cancer-associated changes in glycosylation. To evaluate lectin-cancer cell interactions we developed a novel cell biosensor in which binding events take place at the cell surface, more closely mimicking anin vivosystem. Metastatic, SW620, and non-metastatic, SW480, colorectal cancer cells were grown on the surface of a tissue-culture compatible polystyrene coated biosensor chip and housed in a quartz crystal microbalance (QCM) apparatus, the kinetics of binding of a diverse range of lectins was evaluated. The lectinHelix pomatiaagglutinin (HPA) has been shown to bind aggressive metastatic cancer and was produced in recombinant form (His- and RFP-tagged). The affinity of HPA was in the nanomolar range to the metastatic SW620 cells but was only in the micromolar range to the non-metastatic SW480. Overall, the dissociation constant (KD) of the lectins tested in the new cell biosensor system was an order of magnitude lower (nanomolar range) than has generally been reported with systems such as QCM/SPR. This new cell-biosensor enables molecular interactions to be studied in a more relevant environment. An intrinsic problem with developing new biological therapies is the difficulty in determining the affinity with which proteins will interact with intact cell surfaces. This methodology will be of interest to researchers developing new biological approaches for targeting cell surfaces in a wide range of diseases, including cancer.

Highlights

► A novel system in which cells are grown on a biosensor chip is described. ► Affinity measurements are made directly at the cell surface. ► The sensor surface is regenerated and can be used for up to 30 experiments. ► A new method for testing novel biological reagents that target the cell surface.

A study of electrochemical biosensor for analysis of three-dimensional (3D) cell culture

25 February 2012, 21:52:54Go to full article
Publication year: 2012
Source: Biosensors and Bioelectronics, Available online 25 February 2012
Se Hoon Jeong, Dong Woo Lee, Sanghyo Kim, Jhingook Kim, Bosung Ku
Cell culture has a fundamental role not only in regenerative medicine but also in biotechnology, pharmacology, impacting both drug discovery and manufacturing. Although cell culture has been generally developed for only two-dimensional (2D) culture systems, three-dimensional (3D) culture is being spotlighted as the means to mimic in vivo cellular conditions. In this study, a method for cytotoxicity assay using an electrochemical biosensor applying 3D cell culture is presented. In order to strengthen the advantage of a 3D cell culture, the experimental condition of gelation between several types of sol-gels (alginate, collagen, matrigel) and cancer cells can be optimized to make a 3D cell structure on the electrode, which will show the reproducibility of electrical measurement for long-term monitoring. Moreover, cytotoxicity test results applying this method showed IC50value of A549 lung cancer cells to erlotinib. Thus, this study evaluates the feasibility of application of the electrochemical biosensor for 3D cell culture to cytotoxicity assay for investigation of 3D cell response to drug compounds.

Highlights

► Characterization of an electrochemical biosensor for analysis of 3D cell culture. ► Optimization for enhancement of electrical signal effectiveness in 3D cell culture. ► Electrochemical Measurement of cell viability according to cell seeding density. ► Drug dose response on the electrochemical biosensor applying 3D cell culture. ► We confirmed the feasibility of application of the electrochemical biosensor for analysis of 3D cell culture to cytotoxicity assay by investigating the drug efficacy of erlotinib with the biosensor.

SFT - HPR Series - High Pressure Chemical Reactors

Supercritical Fluid Technologies has a series of stirred reactors for high pressure chemistry. The HPRSeries Reactors have been designed for researchers who are interested in performing pressurized chemical reactions in their laboratories. Whether it is high pressure chemical synthesis or process development, the HPR Series is an excellent unit for those applications.

The reactors range in size from 50 ml to 4 liters and may be operated up to 10,000 psi and 350°C. The reactors have a magnetically coupled impeller for optimal mixing. All high pressure components are ASME rated and protected by a rupture disc for safe operation. These laboratory bench top models are ideal for applications where repetitive use makes convenience a necessity, such as catalytic studies, polymerization, hydrogenation, oxidation, isomerization, and dehydrogenation. All sizes are supplied as ready-to-use instruments requiring only utility connections prior to operation. The reactors are compact instruments that fit easily into a fume hood. Their modular design makes it simple and cost-effective to alter the unit’s basic configuration to adapt to new or evolving application needs.

All functions for the HPR Series Reactor are controlled by choices of three integrated RxTrol™ processors. The RxTrol Sr. offer advanced features utilizing a microcontroller to perform all PID, ramp/soak, process trending, mixing and interlock functions.  The RxTrol Jr. consists of (2) temperature sensors (wall/interior mounting), and fuzzy logic PID temperature controls and mixing controls in a table top assembly.  The RxTrol B consists of (2) temperature sensors (wall/interior mounting) and an open loop mixer speed control via 0-100% power output knob. 

Additional options include vessel windows (<150 degrees Celsius operation only), additional ports, cooling coils, sample loops, stand alone pressure transducers, supercritical fluids pumps and reagent addition modules.

For more information, please call us at 302-738-3420 or visit us on-line at www.supercriticalfluids.com.

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The AC600 Series of ductless chemical workstations are designed to provide a low cost solution for protection of the operator and environment from toxic vapors, gases, fumes and particulate when performing low-volume applications with known chemicals. While smaller and more mobile than a traditional or ductless fume hood, AC600 Series chemical workstations include the same advanced safety features and technology as their larger brethren – gas phase bonded carbon filtration, real-time gas detection and constant airflow control and monitoring.

AirClean® Systems ductless fume hoods and chemical workstations utilize gas phase bonded carbon filtration, providing higher capacity and eliminating filter ‘dusting’ caused by traditional granular carbon filters. In addition to standard formulations, multi-layered and chemically-impregnated filters are available to increase load capacity. AC600 Series workstations can even be configured with multiple carbon and HEPA filters.

The AirSafe™ automatic safety controller, a standard feature on all AC600 Series workstations, displays, monitors and maintains proper airflow to ensure fumes and vapors do not enter the operator’s breathing zone. Regardless of sash position, the microprocessor-based controller will automatically raise or lower the blower speed to maintain the user-set face velocity. In addition to monitoring and controlling airflow, AirSafe monitors gas phase filtration, providing both audible and visible alarms once saturation reaches the alarm set-point.

AC600 Series workstations can be placed virtually anywhere within the laboratory with the only installation requirement being access to a standard power outlet. Each workstation is available with an optional sturdy cart, allowing flexibility and mobility within the laboratory. AC600 Series workstations are self contained, fully assembled, factory tested and certified before shipment.

Typical applications include general chemistry involving small volumes of common chemicals, tissue staining, gluing operations, cleaning and polishing of parts, sample preparation, soldering applications and a variety of other common laboratory manipulations and formulations

AirClean Systems AC600 Series ductless chemical workstations are proudly manufactured in Raleigh, NC USA.

For more information on AirClean Systems’ ductless chemical workstations or fume hoods, visit our website at http://www.aircleansystems.com/ or contact our Technical Sales Department at 919-255-3220 or 800-849-0472.

Monday, 27 February 2012

Just Published: Analytica Chimica Acta

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:

Nonenzymatic glucose sensor based on CuO microfibers composed of CuO nanoparticles

25 February 2012, 22:52:23Go to full article
Publication year: 2012
Source: Analytica Chimica Acta, Available online 25 February 2012
Fei Cao, Jian Gong
Fluorine tin oxide (FTO) electrode modified by copper oxide microfibers (CuO-MFs) composed of numerous interconnected CuO nanoparticles (CuO-NPs) for nonenzymatic glucose sensor was prepared by electrospinning precursor containing high percentage content of copper nitrate with subsequent calcination. The results of scanning electron microscope (SEM) showed the size of CuO particles composing CuO-MFs depended on the percentage content of copper nitrate in precursor solution. With increasing the percentage content of copper nitrate, the interconnected CuO-NPs would gradually replace the large-size CuO particles to accumulate the CuO-MFs, which have the potential to provide larger surface area and more reaction sites for electrocatalytic activity toward glucose. As a glucose sensor, the CuO-MFs modified FTO electrode prepared by 40 wt.% of copper nitrate exhibited a high sensitivity of 2321 μA mM cmwith a low detection limit of 2.2 nM (signal/noise ratio (S/N) = 3). Additionally, the application of the CuO-MFs modified FTO electrode as a glucose sensor for biological samples was demonstrated with satisfactory results.

Highlight

► Electrospinning CuO microfibers onto electrodes as glucose sensors were studied. ► The CuO microfibers were composed of CuO particles. ► Size of CuO particles relies on percentage content of copper nitrate in precursor. ► Performance of the sensor depends on size of CuO particles.

Electrochemical sensor for naphthols based on gold nanoparticles/hollow nitrogen-doped carbon microsphere hybrids functionalized with SH-β-cyclodextrin

25 February 2012, 22:52:23Go to full article
Publication year: 2012
Source: Analytica Chimica Acta, Available online 25 February 2012
Gangbing Zhu, Pengbo Gai, Yan Yang, Xiaohua Zhang, Jinhua Chen
Due to awfully harmful to the environment and human health, the qualitative and quantitative determinations of naphthols [1-naphthol (1-NAP) and 2-naphthol (2-NAP)] are of great significance and receive great attention. In this paper, gold nanoparticles (Au NPs)/hollow nitrogen-doped carbon microspheres (HNCMS) hybrids (Au NPs/HNCMS) were prepared and functionalized with thiolated-β-cyclodextrin (HS-β-CD) for the first time, and then applied successfully in sensitive and simultaneous electrochemical detection of naphthols. The results show that the oxidation peak currents of naphthols obtained on the HS-β-CD/AuNPs/HNCMS modified glassy carbon (GC) electrode are much higher than that on the AuNPs/HNCMS/GC, HNCMS/GC and bare GC electrodes. Additionally, compared with other electrochemical sensors developed previously, the proposed electrode results in improved detection limits of about four times for 1-NAP (1.0 nM) and two orders of magnitude for 2-NAP (1.2 nM). The linear response ranges of 1-NAP and 2-NAP are both 2–150 nM.

Highlights

► HS-β-CD/Au NPs/hollow nitrogen-doped carbon microspheres hybrids were synthesized. ► A new electrochemical sensor for naphthols was developed based on the prepared hybrids. ► The sensor shows good analytical performance for simultaneous detection of naphthols.

Glucose Biosensor Based on Three Dimensional Ordered Macroporous Self-doped Polyaniline/Prussian Blue Bicomponent Film

25 February 2012, 22:52:23Go to full article
Publication year: 2012
Source: Analytica Chimica Acta, Available online 24 February 2012
Xiaojun Chen, Zixuan Chen, Rong Tian, Wei Yan, Cheng Yao
In this paper, a three dimensional ordered macroporous self-doped polyaniline/Prussian blue (3DOM SPAN/PB) bicomponent film was fabricated via the inverted crystal template technique using step-by-step electrodeposition. In this bicomponent film, PB not only acted as a redox mediator, but also presented increased stability in neutral or weak alkaline solution by the protection of SPAN layer on the top. A novel glucose biosensor was fabricated based on the large active surface area and excellent conductivity possessed by the 3DOM SPAN/PB film. The applying experimental conditions of the glucose biosensor have been optimized. Under the optimal conditions, the biosensor showed a wide linear range over three orders of magnitude in glucose concentrations (from 2 to 1600 μM) and a low detection limit of 0.4 μM. Moreover, the biosensor exhibited short response time, high selectivity and excellent operation stability, which can be applied to detect the blood sugar in real samples without any pretreatment.

Highlights

► A 3D ordered macroporous self-doped polyaniline/Prussian blue film was prepared. ► In the film, PB revealed good stability in neutral and weak alkalescent solution. ► A novel glucose biosensor was fabricated based on the 3DOM bicomponet film. ► The biosensor showed a linear range of 2-1600 μM and a detection limit of 0.4 μM. ► The biosensor can detect the blood sugar in real samples without any pretreatment.

Detection of influenza A virus based on fluorescence resonance energy transfer from quantum dots to carbon nanotubes

25 February 2012, 22:52:23Go to full article
Publication year: 2012
Source: Analytica Chimica Acta, Available online 24 February 2012
Junping Tian, Huimin Zhao, Meng Liu, Yaqiong Chen, Xie Quan
In this paper, a simple and sensitive approach for H5N1 DNA detection was described based on the fluorescence resonance energy transfer (FRET) from quantum dots (QDs) to carbon nanotubes (CNTs) in a QDs-ssDNA/oxCNTs system, in which the QDs (CdTe) modified with ssDNA were used as donors. In the initial stage, with the strong interaction between ssDNA and oxCNTs, QDs fluorescence was effectively quenched. Upon the recognition of the target, the effective competitive bindings of it to QDs-ssDNA occurred, which decreased the interactions between the QDs-ssDNA and oxCNTs, leading to the recovery of the QDs fluorescence. The recovered fluorescence of QDs was linearly proportional to the concentration of the target in the range of 0.01-20 μM with a detection limit of 9.39 nM. Moreover, even a single-base mismatched target with the same concentration of target DNA can only recover a limited low fluorescence of QDs, illustrating the good anti-interference performance of this QDs-ssDNA/oxCNTs system. This FRET platform in the QDs-ssDNA/oxCNTs system was facilitated to the simple, sensitive and quantitative detection of virus nucleic acids and could have a wide range of applications in molecular diagnosis.

Highlights

► The quantum dots-ssDNA probe was designed for the determination of virus DNA; ► The fluorescence of quantum dots was effectively quenched by carbon nanotubes; ► The addition of target H5N1 DNA restored the quenched fluorescence of quantum dots; ► The proposed method exhibited high sensitivity and good selectivity for H5N1 DNA.

A colorimetric and Surface-enhanced Raman scattering dual-signal sensor for Hgbased on Bismuthiol II-capped gold nanoparticles

25 February 2012, 22:52:23Go to full article
Publication year: 2012
Source: Analytica Chimica Acta, Available online 24 February 2012
Junling Duan, Min Yang, Yongchao Lai, Jingpeng Yuan, Jinhua Zhan
The addition of Bismuthiol II to the gold nanoparticles (AuNPs) solution led to the aggregation of AuNPs with a color change from red to blue. As a result, hot spots were formed and strong surface-enhanced Raman scattering (SERS) signal of Bismuthiol II was observed. However,the Bismuthiol II-induced aggregation of AuNPs could be reversed by Hgin the system, accompanied by a remarkable color change from blue to red. As evidenced by UV-vis and SERS spectroscopy, the variation in absorption band and SERS intensity was strongly dependent on the concentration of Hg, suggesting a colorimetric and SERS dual-signal sensor for Hg. The sensor had a high sensitivity, low detection limits of 2 nM and 30 nM could be achieved by UV-vis spectroscopy and by SERS spectroscopy, respectively. Other environmentally relevant metal ions did not interfere with the detection of Hg. The method was successfully applied to detect Hgin water samples. It was simple, rapid and cost-effective without any modifying or labeling procedure.

Highlights

► A dual-signal sensor for Hgwas developed by mixing Bismuthiol II and AuNPs. ► Colorimetric sensing was achieved based on the Hg-inhibited aggregation of AuNPs. ► Hot spots were formed with the aggregation of AuNPs, allowing SERS detection. ► The method showed high sensitivity and selectivity.

Electrochemical detection of a powerful estrogenic endocrine disruptor: ethinylestradiol in water samples through bioseparation procedure

25 February 2012, 22:52:23Go to full article
Publication year: 2012
Source: Analytica Chimica Acta, Available online 24 February 2012
Noelia A. Martínez, Sirley V. Pereira, Franco A. Bertolino, Rudolf J. Schneider, Germán A. Messina, ...
The synthetic estrogen ethinylestradiol (EE2) is an active component of oral contraceptives (OCs), considered as an endocrine disrupting compound (EDC). It is excreted from humans and released via sewage treatment plant effluents into aquatic environments. EDCs are any environmental pollutant chemical that, once incorporated into an organism, affects the hormonal balance of various species including humans. Its presence in the environment is becoming of great importance in water quality. This paper describes the development of an accurate, sensitive and selective method for capture, preconcentration and determination of EE2 present in water samples using: magnetic particles (MPs) as bioaffinity support for the capture and preconcentration of EE2 and a glassy carbon electrode modified with multi-walled carbon nanotubes (MWCNTs/GCE) as detection system. The capture procedure was based on the principle of immunoaffinity, the EE2 being extracted from the sample using the anti-EE2 antibodies (anti-EE2 Ab) which were previously immobilized on MPs. Subsequently the analyte desorption was done employing a sulfuric acid solution and the determination of the EE2 in the pre-concentrated solution was carried out by square wave voltammetry (SWV).This method can be used to determine EE2 in the range of 0.035–70 ng Lwith a detection limit (LOD) of 0.01 ng Land R.S.D. < 4.20%. The proposed method has been successfully applied to the determination of EE2 in water samples and it has promising analytical applications for the direct determination of EE2 at trace levels.

Highlights

► We developed an electrochemical method for the determination of ethinylestradiol in water samples. ► Modified magnetic particles were employed for the bioseparation and preconcentration procedures. ► The use of magnetic particles offers high selectivity due to antigen-antibody binding specificity. ► The detection was carried out by using a glassy carbon electrode modified with carbon nanotubes.

NEW CO2 Data Logger with Temperature & Humidity!

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Friday, 24 February 2012

Just Published: Sensors & Actuators A: Physical

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:

Numerical study of a ferrule-top cantilever optical fiber sensor for wind-tunnel applications and comparison with experimental results

22 February 2012, 21:56:07
Publication year: 2012
Source: Sensors and Actuators A: Physical, Available online 22 February 2012
A. Cipullo, G. Gruca, K. Heeck, F. De Filippis, D. Iannuzzi, ...
We present a numerical analysis of an air flow velocity sensor based on a fiber-optic ferrule-top cantilever. The device forms a low-finesse Fabry-Perot interferometer, with one of the two reflecting surfaces constituted by a cantilever beam. Under the effect of the flow pressure, the cantilever bends producing a change in the cavity length of the Fabry-Perot and therefore a modification of its optical response. The numerical analysis, performed by use of finite-element method (FEM), is then compared with a set of experimental results obtained in a small wind-tunnel.

Silicon linkage with novel compliant mechanism for piezoelectric actuation of an intraocular implant

22 February 2012, 21:56:07
Publication year: 2012
Source: Sensors and Actuators A: Physical, Available online 22 February 2012
Th. Martin, U. Gengenbach, H. Guth, P. Ruther, O. Paul, ...
An implantable mechatronic microsystem is a new approach to restore the accommodation ability of the human eye. For change of refractive power a lens shift is performed by an actuator. This paper reports on the first actuator solution for such an implant. It is based on a piezoelectric bender the displacement of which has to be amplified on a very limited design space to sufficiently drive the optics of an Artificial Accommodation System. This challenge is solved by a novel compliant mechanism in single-crystal silicon that additionally ensures a linear displacement of the lens required for optical imaging quality. The design is free of any surface-friction to achieve high durability. Finite element analysis is conducted to calculate and optimize the performance of three linkage design variants. They were fabricated on a scale of 1.5:1 using deep reactive ion etching. Measurements were carried out to characterize the geometry, elastic behavior, and kinematic performance of the linkage samples. The results are in very good agreement with the calculations and indicate sufficient amplification of the piezoelectric bender's displacement by the linkage to generate the required lens shift.

Ku-band bandpass filters using novel micromachined substrate integrated waveguide structure with embedded silicon vias in benzocyclobutene dielectrics

22 February 2012, 21:56:07
Publication year: 2012
Source: Sensors and Actuators A: Physical, Available online 21 February 2012
Ik-Jae Hyeon, Woo-Young Park, Sungjoon Lim, Chang-Wook Baek
In this paper, Ku-band bandpass filters (BPFs) based on a novel micromachined substrate integrated waveguide (SIW) platform with square complementary split-ring resonators (CSRRs) have been demonstrated. The proposed SIW platform adopts embedded metal-coated silicon vias in benzocyclobutene (BCB) dielectric substrate filled into a silicon trench. Unlike conventional SIW BPFs using classical microwave substrates, the proposed BPFs can be integrated with silicon-based circuits or RF MEMS devices since the fabrication process is fully compatible with the silicon process while providing low-loss properties of the waveguide. Three types of BPFs using CPW and microstrip feeding configurations have been designed and fabricated. The microstrip-fed BPF using the same CSRRs shows an improved insertion loss of 1.39 dB at 13.8 GHz with reduced device size compared to the CPW-fed BPF which has an insertion loss of 2.27 dB at 14.1 GHz. The microstrip-fed BPF with different CSRR configurations designed to improve shape factor shows an attenuation factor of 124 dB/GHz, with an insertion loss of 2.3 dB at 21.2 GHz.

Effects of wire properties on the field-tunable behaviour of continuous-microwire composites

22 February 2012, 21:56:07
Publication year: 2012
Source: Sensors and Actuators A: Physical, Available online 21 February 2012
F.X. Qin, H.X. Peng, M.H. Phan, L.V. Panina, M. Ipatov, ...
The microwire composites consisting of continuous Co-rich amorphous glass-coated ferromagnetic microwires embedded in a E-glass prepreg matrix were fabricated, and the influences of wire periodicity (b), composition and radius on the field-tunable properties have been systematically investigated in a broad microwave frequency range of 0.9–18 GHz. It has been found that the field tunability, effective operational frequency and field of the composites are strongly dependent on these factors. With decreasingbfrom 15 to 7 mm, the field tunability of effective permittivity (nɛ) increases from 0.77% to 16% m/A by more than 20 times. The detected cups and resonances of the transmission and reflection spectra are identified. Their changes with wire periodicity have been shown to be due to a combination of the dielectric and magnetic response arising from the interactions between microwave and microwires and microwires by themselves. The best possible field tunability occurs below the plasma frequency. The effective magnetic field for realisation of the field-tunable properties has been found to be about 500 A/m, which is associated with the anisotropy field. In addition, field tunability is found to be positively correlated with the magnetic softness and GMI properties of the wire fillers, which are determined by the wire composition and geometry. These findings are of practical importance in developing multifunctional microwire composites for a broad range of engineering applications, such as structural health monitoring, NDT and microwave tunable devices.

Highlights

► Exhaustive presentation and analyses of the influences of wire periodicity (b), composition and radius on the field-tunable properties ► Plasma frequency, field tunability and effective operation frequency range can be modulated via fine-tuning the local properties and arrangements of wires ► Detailed and comprehensive comparison is performed for feature differences in all electromagnetic spectra due to the variation of the wire parameters.


Porvair Sciences Announces 2012 Microplate Catalogue

Many scientists around the world have come to rely upon the Porvair Sciences Catalogue as a primary source of information that enables them to choose the optimum microplate or tissue culture consumable for their application.

The new 2012 edition brings together information on Porvair Sciences comprehensive microplate and microplate instruments product range, together with a recently introduced range of high quality epigenetics and tissue culture plastics. Reflecting Porvair's continuing commitment to continuous technological innovation, the 2012 catalogue introduces a suite of exciting new products.

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For a copy of the 2012 catalogue please visit www.porvair-sciences.com or contact Porvair Sciences Ltd. on +44-1372-824290 / int.sales@porvair-sciences.com  


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Thursday, 23 February 2012

Just Published: Journal of Chromatography A



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:

Packed Column Supercritical Fluid Chromatography (pcSFC) of Hydrophilic Analytes via Water-Rich Modifiers

22 February 2012, 21:55:48Go to full article
Publication year: 2012
Source: Journal of Chromatography A, Available online 22 February 2012
Larry T. Taylor
The use of additives to dramatically extend the range of solute polarity amenable to CO2based supercritical fluid chromatography (pcSFC) was predicted over twenty years ago. At that time additives were predicted to have multiple functions such as enhancement of mobile phase solvating power, ion suppression, and ion pairing. The adsorption of mobile phase components on the stationary phase causing a modification of its surface was predicted, but the implications for separations were not defined. Reports published in the late 1980‘s showed that while water could not function as a primary modifier due to it poor solubility in carbon dioxide, its use as an additive was more promising. The past decade has seen very little published work concerning water and pcSFC. Now reports are beginning to appear that demonstrate enhanced selectivity with water, and application of the technology to polypeptide salts, drug molecules, and nucleobases. This review attempts to bridge the past with the present. As evidenced by the studies described in this review, water may offer much potential as an additive in that it could (a) enhance the solvating power of the mobile phase, (b) introduce HILIC-like analyte partitioning, (c) simplify preparative purifications, and (d) offer a more mass spectrometrically compatible interface.

Highlights

► Water as a neutral additive has been shown to enhance pcSFC selectivity. ► Water enhances solvation of polar analytes and the stationary phase. ► After 20 years, water is finding new applications in pcSFC.

Determination of Tropane Alkaloids Atropine and Scopolamine by Liquid Chromatography-Mass Spectrometry in Plant Organs of Datura Species

22 February 2012, 21:55:48Go to full article
Publication year: 2012
Source: Journal of Chromatography A, Available online 22 February 2012
Silvia Jakabová, Lajos Vincze, Ágnes Farkas, Ferenc Kilár, Borbála Boros, ...
Hyoscyamine (atropine) and scopolamine are the predominant tropane alkaloids in theDaturagenus, occurring in all plant organs. The assessment of the alkaloid content of various plant parts is essential from the viewpoint of medical use, but also as a potential risk of toxicity for humans and animals. Therefore, a reliable method for the determination of tropane alkaloid content is of high importance.The present work aimed at the elaboration of a rapid method for determination of the most abundantDaturaalkaloids by LC-MS technique using a new generation of core-shell particle packed column. Tropane alkaloid content was investigated in various plant organs of fourDaturataxa (D. innoxia, D. metel, D. stramonium, andD. stramoniumvar.tatula), grown under the same conditions, in two developmental stages.We have developed a rapid LC-MS method for the quantitative determination of atropine and scopolamine, which was successfully applied to quantify the alkaloids in different plant organs (leaves, flowers, stems, seeds) of thorn apples after a simple sample preparation step. Elaboration and validation of the method and analysis of plant extracts were done by UFLC-MS technique, employing an Ascentis Express C18 column. Detection was done in positive ionization mode (ESI + ) and the method suitability was evaluated by several validation characteristics. Quantitation limits are 333 and 167 pg mLfor scopolamine and atropine, respectively, and the method shows very good repeatability.The analysis ofDaturaextracts revealed significant differences depending on the species, the organ and the sampling period. Atropine was found to be dominant over scopolamine in three out of the four taxa investigated.D. innoxiashowed the highest concentrations of scopolamine in all organs examined, whereasD. metelaccumulated the lowest scopolamine levels. Hyoscyamine, measured as atropine, was the highest inD. stramoniumvar.tatula, and the lowest inD. innoxia. Samples collected in summer had higher scopolamine levels than autumn samples, concerning both stems and leaves.

Highlights

► We have developed a rapid LC-MS method for the quantitative determination of atropine and scopolamine. ► The method was successfully applied to quantify the alkaloids in different plant organs (leaves, flowers, stems, seeds) of thorn apples after a simple sample preparation step. ► Lower limits of quantitation are 333 and 167 pg mL-1 for scopolamine and atropine, respectively, and the method shows very good repeatability. ► The analysis ofDaturaextracts revealed significant differences depending on the species, the organ and the sampling period.

Determination of triazine herbicides in cereals using dynamic microwave-assisted extraction with solidification of floating organic drop followed by high-performance liquid chromatography

22 February 2012, 21:55:48Go to full article
Publication year: 2012
Source: Journal of Chromatography A, Available online 21 February 2012
Hui Wang, Guijie Li, Yiqun Zhang, Haiyan Chen, Qi Zhao, ...
A simple and cost-effective method of dynamic microwave-assisted extraction (DMAE) combined with solidification of floating organic drop (SFO) was developed for determining the five triazine herbicides in cereals. The approach combines the advantages of DMAE and SFO technique, and up to 15 samples can be treated simultaneously in 16 min. Firstly, triazine herbicides were extracted with 1 mL of methanol containing 90 μL of 1-dodecanol and following with 10 mL of water under the action of microwave energy. After that, 1.5 g sodium chloride was added into the obtained extract, and the mixture was centrifuged and cooled. The 1-dodecanol drop which contained the target analytes was solidified and transferred for analysis by HPLC-UV. Limits of detection of the five triazines obtained were in the range of 1.1-1.5 ng g. Relative standard deviations of intra- and inter-day tests ranging from 5% to 7% were obtained. The method was successfully applied to the analysis of ten cereals and the recoveries of the triazines for the spiked samples were in the range of 80-102%. The proposed method is an alternative approach to the analysis of triazine herbicides in complex solid samples, being more rapid and simpler compared with the traditional extraction method.

Highlights

► Cereal samples were extracted by dynamic microwave-assisted extraction technology. ► Triazine herbicides in the extract were enriched by 90 μL of 1–dodecanol. ► Extraction and enrichment were completed in a single step. ► The solidified 1–dodecanol contained triazines was analyzed by HPLC–UV. ► Up to 15 samples can be treated simultaneously in 16 min.

Liquid chromatography-flame ionisation detection using a nebuliser/spray chamber interface. Part 2. Comparison of functional group responses

22 February 2012, 21:55:48Go to full article
Publication year: 2012
Source: Journal of Chromatography A, Available online 21 February 2012
Erepamowei Young, Roger M. Smith, Barry L. Sharp, Joanne R. Bone
The application of a LC-nebuliser/spray chamber interface-flame ionization detection has been demonstrated for the superheated water liquid chromatography of a wide range of aliphatic and aromatic analytes. The linearity and sensitivity of the response of volatile and involatile analytes have been compared. The response of the detector towards different analytes is similar to that in GC-FID and for volatile analytes was comparable to UV detection. However, the responses from involatile analytes, such as amino-acids and carbohydrates, was poor and often lower than for a refractive index detector.

Highlights

► A LC-nebuliser/spray chamber interface-flame ionization detection for superheated water liquid chromatography ► responds to a wide range of aliphatic and aromatic analytes ► linearity and sensitivity of the response of volatile and involatile analytes compared ► response of detector compared to GC-FID ► compared to UV and RI detectors

Erratum to “Processing nanoparticles with A4F-SAXS for toxicological studies: Iron oxide in cell-based assays” [J. Chromatogr. A 1218 (2011) 4160–4166]

22 February 2012, 21:55:48Go to full article
Publication year: 2012
Source: Journal of Chromatography A, Available online 21 February 2012
Patrick Knappe, Linda Boehmert, Ralf Bienert, Silvana Kamutzki, Birgit Niemann, ...

Predictions of comprehensive two-dimensional gas chromatography separations from isothermal data

20 February 2012, 22:49:46Go to full article
Publication year: 2012
Source: Journal of Chromatography A, Available online 18 February 2012
Shukui Zhu, Sheng He, David R. Worton, Allen H. Goldstein
Two-dimensional retention times and peak widths in temperature programmed comprehensive two-dimensional gas chromatography were predicted using a theoretical model developed from experimental data obtained under isothermal conditions. A Matlab program was written to calculate the following parameters: dead time (tM), elution temperature (Te), retention time (tR), hold-up width (wM) and peak width (wR). The two-dimensional retention times of a sample mixture that contained n-alkanes and polyaromatic hydrocarbons (PAHs) were predicted and were observed to be in excellent agreement with experimentally determined values. The relative deviation between the model and the experimental data was less than 2 and 7% for the primary and secondary retention times, respectively. The relative deviation of peak width was less than 7 and 10% in the primary and secondary dimensions, respectively. The advantage of this model was its simplicity, informed entirely from experimental data, with no reliance on theoretical parameters. This prediction model would be useful for optimizing GC × GC separation conditions and for confirming compound identifications of components that are chromatographically resolved but that have nearly identical mass spectra.