World Congress on Biosensors 2014

World Congress on Biosensors 2014
Biosensors 2014

Friday 30 August 2013

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:

Recent advances in biosensor based endotoxin detection

29 August 2013, 19:29:09
Publication date: 15 January 2014
Source:Biosensors and Bioelectronics, Volume 51
Author(s): A.P. Das , P.S. Kumar , S. Swain
Endotoxins also referred to as pyrogens are chemically lipopolysaccharides habitually found in food, environment and clinical products of bacterial origin and are unavoidable ubiquitous microbiological contaminants. Pernicious issues of its contamination result in high mortality and severe morbidities. Standard traditional techniques are slow and cumbersome, highlighting the pressing need for evoking agile endotoxin detection system. The early and prompt detection of endotoxin assumes prime importance in health care, pharmacological and biomedical sectors. The unparalleled recognition abilities of LAL biosensors perched with remarkable sensitivity, high stability and reproducibility have bestowed it with persistent reliability and their possible fabrication for commercial applicability. This review paper entails an overview of various trends in current techniques available and other possible alternatives in biosensor based endotoxin detection together with its classification, epidemiological aspects, thrust areas demanding endotoxin control, commercially available detection sensors and a revolutionary unprecedented approach narrating the influence of omics for endotoxin detection.

Colorimetric detection of controlled assembly and disassembly of aptamers on unmodified gold nanoparticles

29 August 2013, 19:29:09
Publication date: 15 January 2014
Source:Biosensors and Bioelectronics, Volume 51
Author(s): Subash C.B. Gopinath , Thangavel Lakshmipriya , Koichi Awazu
Aptamers are nucleic acid ligands that are generated artificially by in vitro selection and behave similar to antibodies. The development of aptamer-based sensing systems or strategies has been in vogue for the past few decades, because aptamers are smaller in size, stable, cheaper and undergo easier modifications. Owing to these advantages, several facile aptamer-based colorimetric strategies have been created by controlling the assembly and disassembly of aptamers on unmodified gold nanoparticle probes. As these kinds of assay systems are rapid and can be visualized unaided by instruments, they have recently become an attractive method of choice. The formation of purple-colored aggregates (attraction) from the red dispersed (repulsion) state of GNPs in the presence of mono- or divalent ions is the key principle behind this assay. Due to its simplicity and versatility, this assay can be an alternative to existing diagnostic assays. Here, we have investigated the critical elements involved in colorimetric assays, and have screened different proteins and small ligands to evaluate biofouling on GNPs.

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Surface stress-based biosensors

29 August 2013, 19:29:09
Publication date: 15 January 2014
Source:Biosensors and Bioelectronics, Volume 51
Author(s): Shengbo Sang , Yuan Zhao , Wendong Zhang , Pengwei Li , Jie Hu , Gang Li
Surface stress-based biosensors, as one kind of label-free biosensors, have attracted lots of attention in the process of information gathering and measurement for the biological, chemical and medical application with the development of technology and society. This kind of biosensors offers many advantages such as short response time (less than milliseconds) and a typical sensitivity at nanogram, picoliter, femtojoule and attomolar level. Furthermore, it simplifies sample preparation and testing procedures. In this work, progress made towards the use of surface stress-based biosensors for achieving better performance is critically reviewed, including our recent achievement, the optimally circular membrane-based biosensors and biosensor array. The further scientific and technological challenges in this field are also summarized. Critical remark and future steps towards the ultimate surface stress-based biosensors are addressed.

Thousand-fold fluorescent signal amplification for mHealth diagnostics

29 August 2013, 19:29:09
Publication date: 15 January 2014
Source:Biosensors and Bioelectronics, Volume 51
Author(s): Joshua Balsam , Reuven Rasooly , Hugh Alan Bruck , Avraham Rasooly
The low sensitivity of Mobile Health (mHealth) optical detectors, such as those found on mobile phones, is a limiting factor for many mHealth clinical applications. To improve sensitivity, we have combined two approaches for optical signal amplification: (1) a computational approach based on an image stacking algorithm to decrease the image noise and enhance weak signals, and (2) an optical signal amplifier utilizing a capillary tube array. These approaches were used in a detection system which includes multi-wavelength LEDs capable of exciting many fluorophores in multiple wavelengths, a mobile phone or a webcam as a detector, and capillary tube array configured with 36 capillary tubes for signal enhancement. The capillary array enables a ∼100× increase in signal sensitivity for fluorescein, reducing the limit of detection (LOD) for mobile phones and webcams from 1000nM to 10nM. Computational image stacking enables another ∼10× increase in signal sensitivity, further reducing the LOD for webcam from 10nM to 1nM. To demonstrate the feasibility of the device for the detection of disease-related biomarkers, adenovirus DNA labeled with SYBR green or fluorescein was analyzed by both our capillary array and a commercial plate reader. The LOD for the capillary array was 5ug/mL, and that of the plate reader was 1ug/mL. Similar results were obtained using DNA stained with fluorescein. The combination of the two signal amplification approaches enables a ∼1000× increase in LOD for the webcam platform. This brings it into the range of a conventional plate reader while using a smaller sample volume (10ul) than the plate reader requires (100ul). This suggests that such a device could be suitable for biosensing applications where up to 10 fold smaller sample sizes are needed. The simple optical configuration for mHealth described in this paper employing the combined capillary and image processing signal amplification is capable of measuring weak fluorescent signals without the need of dedicated laboratories. It has the potential to be used to increase sensitivity of other optically based mHealth technologies, and may increase mHealth's clinical utility, especially for telemedicine and for resource-poor settings and global health applications.

Fluorescence correlation spectroscopy analysis for accurate determination of proportion of doubly labeled DNA in fluorescent DNA pool for quantitative biochemical assays

29 August 2013, 19:29:09
Publication date: 15 January 2014
Source:Biosensors and Bioelectronics, Volume 51
Author(s): Sen Hou , Lili Sun , Stefan A. Wieczorek , Tomasz Kalwarczyk , Tomasz S. Kaminski , Robert Holyst
Fluorescent double-stranded DNA (dsDNA) molecules labeled at both ends are commonly produced by annealing of complementary single-stranded DNA (ssDNA) molecules, labeled with fluorescent dyes at the same (3′ or 5′) end. Because the labeling efficiency of ssDNA is smaller than 100%, the resulting dsDNA have two, one or are without a dye. Existing methods are insufficient to measure the percentage of the doubly-labeled dsDNA component in the fluorescent DNA sample and it is even difficult to distinguish the doubly-labeled DNA component from the singly-labeled component. Accurate measurement of the percentage of such doubly labeled dsDNA component is a critical prerequisite for quantitative biochemical measurements, which has puzzled scientists for decades. We established a fluorescence correlation spectroscopy (FCS) system to measure the percentage of doubly labeled dsDNA (PDL) in the total fluorescent dsDNA pool. The method is based on comparative analysis of the given sample and a reference dsDNA sample prepared by adding certain amount of unlabeled ssDNA into the original ssDNA solution. From FCS autocorrelation functions, we obtain the number of fluorescent dsDNA molecules in the focal volume of the confocal microscope and PDL. We also calculate the labeling efficiency of ssDNA. The method requires minimal amount of material. The samples have the concentration of DNA in the nano-molar/L range and the volume of tens of microliters. We verify our method by using restriction enzyme Hind III to cleave the fluorescent dsDNA. The kinetics of the reaction depends strongly on PDL, a critical parameter for quantitative biochemical measurements.

Real-time and non-invasive impedimetric monitoring of cell proliferation and chemosensitivity in a perfusion 3D cell culture microfluidic chip

29 August 2013, 19:29:09
Publication date: 15 January 2014
Source:Biosensors and Bioelectronics, Volume 51
Author(s): Kin Fong Lei , Min-Hsien Wu , Che-Wei Hsu , Yi-Dao Chen
A perfusion three-dimensional (3D) cell culture microfluidic chip has been developed for real-time and non-invasive impedimetric monitoring of cell proliferation and chemosensitivity. In this study, human oral cancer cells (OEC-M1) were encapsulated in 3D agarose scaffold and cultured in a miniaturized chamber under perfusion of tested substance. This setting provides a more in vitro physiologically relevant microenvironment to better mimic the complex in vivo microenvironment. A pair of vertical electrodes was embedded at the opposite sidewalls of the culture chamber for the on-site impedance measurement. Cell density in the 3D construct was shown to be proportional to the impedance magnitude of the entire construct. Therefore, perfusion 3D cell culture was performed for up to 5 days and cell proliferation can be monitored by the impedimetric analysis. Moreover, real-time impedimetric monitoring of cell viability under the perfusion of anti-cancer drug in different concentrations was conducted and the impedance magnitude was directly correlated with the cell viability. From the confirmation of the endpoint cell viability assays, a concentration-dependent effect was shown; however, the response of cell viability during the drug treatment was able to be traced by the impedance measurement. The experimental results showed that cell proliferation and chemosensitivity in 3D cell culture format can be monitored by impedance measurement. This microfluidic chip has a high potential to develop a powerful analytical platform for cancer research.

Electrochemical sensing interfaces with tunable porosity for nonenzymatic glucose detection: A Cu foam case

29 August 2013, 19:29:09
Publication date: 15 January 2014
Source:Biosensors and Bioelectronics, Volume 51
Author(s): Xiangheng Niu , Yuxiu Li , Jie Tang , Yangliao Hu , Hongli Zhao , Minbo Lan
It is widely thought in electro-biochemical analysis that the sensing interfaces play a key role in the enzymeless detection of biomolecules like glucose, ascorbic acid, dopamine and uric acid. On the way to maximize the anti-poisoning sensitivity of nonenzymatic electrochemical glucose sensors as well as achieve favorable selectivity, we propose here a porous interface fabricated by a facile but effective approach for glucose monitoring in alkaline media containing dissolved oxygen. The sensing interface based on porous Cu foams is directly formed on a homemade disposable screen-printed carbon electrode (SPCE) substrate by electrodeposition assisted with hydrogen evolution simultaneously, and its porosity can be easily tailored through adjusting deposition conditions for the optimal electrocatalytic oxidation of glucose molecules. SEM and BET studies show that the generated Cu foam possesses robust hierarchical porous architectures with greatly enhanced surface area and pore volume, beneficial for the unimpeded mobility of glucose and reaction products. Cyclic voltammetric tests indicate that a diffusion-controlled glucose electro-oxidation reaction occurs at the Cu foam electrode at around +0.35V vs. Ag/AgCl in 0.1M NaOH. Chronoamperometric results obtained under optimized conditions reveal that the proposed sensor exhibits desired poison resistance ability in the presence of chloride ions and significant selectivity to glucose, providing fascinating sensitivities of 2.57 and 1.81mAcm−2 mM−1 for glucose in the linear concentration ranges of 2–80μM and 0.1–5mM, respectively. The limit of detection is calculated to be as low as 0.98μM according to the signal-to-noise ratio of three. In addition, the fabricated sensing interface shows attractive reproducibility (RSD of 5.1% and 7.0% for 15 repeated measurements on a sensor and for measurements on 15 prepared sensors, respectively) and outstanding long-term stability (less than 5% loss in sensitivity over 1 month) for glucose detection. The application of the Cu foam based sensor for monitoring glucose in practical samples is also successfully demonstrated.

Lanthanide-labeled immunochromatographic strips for the rapid detection of Pantoea stewartii subsp. stewartii

29 August 2013, 19:29:09
Publication date: 15 January 2014
Source:Biosensors and Bioelectronics, Volume 51
Author(s): Fan Zhang , Mingqiang Zou , Yan Chen , Jinfeng Li , Yanfei Wang , Xiaohua Qi , Qiang Xue
The lateral flow immunoassay is used in commercial pregnancy detection, and is an accepted point-of-care testing technique. The most widely used format for lateral flow immunochromatographic strips uses gold nanoparticles for colorimetric detection. However, this method often suffers from poor quantitative discrimination and low analytical sensitivity. To address these limitations, lanthanide chelate-loaded silica nanoparticles have been used as fluorescent labels. The fluorescent nanoparticles can easily bind to antibodies, with dextran as a linker. The strip reader described here was based on a sandwich immunoreaction performed on a strip, using lanthanide-labeled antibodies that served as signal vehicles for the fluorescent readout. The strip reader was used as a quantitative test system. In this work, Pantoea stewartii subsp. stewartii (Pss) was used as a model analyte to demonstrate the use of the strip reader. Under optimal conditions, the detection limit was determined as 103 cfu/mL. The quantification limit was calculated to be 104 cfu/mL. The detection limit for Pss was 100 times lower than those displayed by colloidal gold-labeled strips or ELISAs. No cross-reactions were observed with the other nine strains, indicating the good specificity of the Pss strip. This strip showed good stability in repeated tests. The tests using the fluorescence immunochromatographic strip were easy to perform, rapid, and sensitive. Methods using fluorescence strips and a strip reader have the potential to be a powerful tool for the quantification of bacteria.

Hairpin DNA probe with 5′-TCC/CCC-3′ overhangs for the creation of silver nanoclusters and miRNA assay

29 August 2013, 19:29:09
Publication date: 15 January 2014
Source:Biosensors and Bioelectronics, Volume 51
Author(s): Xiaodong Xia , Yuanqiang Hao , Shengqiang Hu , Jianxiu Wang
A facile strategy for the assay of target miRNA using fluorescent silver nanoclusters (AgNCs) has been described. Due to the preferable interaction between cytosine residues and Ag+, a short cytosine-rich oligonucleotide (ODN) with only six bases 5′-TCCCCC-3′ served as an efficient scaffold for the creation of the AgNCs. The AgNCs displayed a bright red emission when excited at 545nm. Such ODN base-stabilized AgNCs have been exploited for miRNA sensing. Overhangs of TCC at the 5′ end (5′-TCC) and CCC at the 3′ end (CCC-3′) (denoted as 5′-TCC/CCC-3′) appended to the hairpin ODN probe which also contains recognition sequences for target miRNA were included. Interestingly, the AgNCs/hairpin ODN probe showed similar spectral properties as that templated by 5′-TCCCCC-3′. The formation of the hairpin ODN probe/miRNA duplex separated the 5′-TCC/CCC-3′ overhangs, thus disturbing the optical property or structure of the AgNCs. As a result, fluorescence quenching of the AgNCs/hairpin ODN probe was obtained, which allows for facile determination of target miRNA. The proposed method is simple and cost-effective, holding great promise for clinical applications.

A novel core-satellite CdTe/Silica/Au NCs hybrid sphere as dual-emission ratiometric fluorescent probe for Cu2+

29 August 2013, 19:29:09
Publication date: 15 January 2014
Source:Biosensors and Bioelectronics, Volume 51
Author(s): Yan-Qin Wang , Tong Zhao , Xi-Wen He , Wen-You Li , Yu-Kui Zhang
Herein, we synthesized a novel core-satellite CdTe/Silica/Au NCs hybrid sphere by covalently linking the separately synthesized highly fluorescent bovine serum albumin (BSA) stabilized gold nanoclusters (Au@BSA NCs) to the surface of the amino functionalized CdTe@SiO2 spheres by using the EDC chemistry. Numerous “satellites” of Au NCs were linked on the surface of the CdTe@SiO2 by the way of amide bonding. The synthesized dual-emission hybrid spheres were further characterized by the transmission electron microscopy (TEM), energy dispersive X-ray spectroscopy (EDS), UV–vis absorption spectroscopy, Fourier transform infrared (FTIR) spectroscopy, photoluminescence (PL), etc. Finally, the CdTe/Silica/Au NCs hybrid spheres were developed as ratiometric fluorescence probe for the determination of Cu2+ with high sensitivity and selectivity. The fluorescence intensity ratio (F 545nm/F 655nm) of the probe against the concentration of Cu2+ showed a good linear relationship from 6.0×10−7 molL−1 to 100.0×10−7 molL−1. It showed an excellent reproducibility (0.67% relative standard deviation for 10 replicate measurements of Cu2+ at 40.0×10−7 molL−1) and low detection limit (4.1×10−7 molL−1). Furthermore, the ratiometric fluorescent probe was successfully applied in the determination of Cu2+ in vegetable samples with satisfactory results.

Development of antibiotic selection kit towards veterinary applications using glycine passivated magnetic particles

29 August 2013, 19:29:09
Publication date: 15 January 2014
Source:Biosensors and Bioelectronics, Volume 51
Author(s): Kaliyaperumal Viswanathan , Gopal Dhinakar Raj , V.Senthil Vadivoo , Kathaperumal Kumanan , Rajamanickam Prabakaran
Glycine functionalized (Gly/Fe3O4) and non-functionalized (Fe3O4) magnetic particles were synthesized in an autoclave and characterized by transmission electron microscopy (TEM), Fourier transformed infrared spectroscopy (FTIR), vibrating sample magnetometer (VSM), energy-dispersive X-ray spectroscopy (EDX), differential scanning calorimetry (DSC), X-ray diffraction patterns (XRD) and zeta potential. The size of the both these particles were in the range of 220–230nm but the shape of the Gly/Fe3O4 particles was hexagonal in contrast to the spherical shape of Fe3O4 particles. The particle characterization tests confirmed that glycine was functionalized on the Gly/Fe3O4 particles, they were positively charged and possessed strong magnetic property. These particles possessed the ability to bind to bacteria such as Escherichia coli, Streptococcus and Staphylococcus in the range of 72−90%. They were used to entrap bacteria from clinical mastitic milk samples from cows. The entrapped bacteria of the above species from these samples were isolated and used individually in the conventional disc-diffusion method of antibiotic susceptibility determination. The results were compared with that of the bacterial species isolated directly from the mastitic milk samples and were found to be 100% concordant (n=25). The developed portable antibiotic selection kit was tested with twenty five samples of mastitic milk. The results indicated that, antibiotic resistant bacteria turned the methylene blue in to white color while the bacteria that were killed (sensitive) retained the blue color of the dye. Thus the right choice of the antibiotic to treat cows with mastitis could be determined based on the naked eye. In conclusion, the kit gave quicker results, was easy to assay and read and can be ‘farm-gate’ applicable than the presently available conventional method.

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Flow-through sensor array applied to cytotoxicity assessment in cell cultures for drug-testing purposes

29 August 2013, 19:29:09
Publication date: 15 January 2014
Source:Biosensors and Bioelectronics, Volume 51
Author(s): Emilia Witkowska Nery , Elżbieta Jastrzębska , Kamil Żukowski , Wojciech Wróblewski , Michał Chudy , Patrycja Ciosek
The viability of cells cultured in microsystems for drug screening purposes is usually tested with a variety of colorimetric/fluorescent methods. In this work we propose an alternative way of assessing cell viability—flow-through sensor array that can be connected in series with cell microbioreactors as compatible detection system. It is shown, that the presented device is capable of cytotoxic effect detection and estimation of cell viability after treatment with 1,4-dioxane and 5-fluorouracil, which proves that it can be used for truly non-invasive, fast, reliable, continuous cell culture monitoring in microscale. 

Cheminert High Pressure Fittings for 360 µm Tubing

VICI Valco’s Cheminert High Pressure PEEK Fittings are rated at 5000 psi with fingertight nuts, well beyond the burst strength of most PEEK tubing. The taper angle and detail design conform to the industry standard established by the Valco line.

The Cheminert UHPLC Fitting designs permit direct connection of 360 micron OD fused silica, PEEK, stainless, or electroformed nickel tubing without having to use troublesome liners. Because of the fitting’s compact size and fine 2-56 threads, a leak-free connection that seals at pressures well in excess of 20,000 psi can be easily formed with the available manual tool. 360 micron fittings in PEEK can be used safely up to 10,000 psi.

The 360 µm fittings are available with a PEEK or stainless nut; the PEEK nut is supplied with a glass-filled PEEK ferrule, while the stainless nut uses a 316 SS ferrule. The ferrule snaps into the nut so that the fitting is “one-piece”, but the ferrule is free to rotate and does not twist the tube as the nut is tightened. A range of micron bore sizes are available.

For more information:  Valco Instruments Co., Inc., Houston, Texas; 
Phone:  (800) 367-8424;   Fax:  (713) 688-3948; Web: www.vici.com;
e-mail: valco@vici.com

PEEK® is a registered trademark of Victrex.

Wednesday 28 August 2013

Euroanalysis XVII #6

Session Chair - and Sensors & Acuators B editor - Zbigniew Brzozka (above) introduces Thomas Laurell (below) who then presents his keynote lecture entitled: Medical Applications of Chip Integrated Acoustophoretic Cell Separation.

SFT-10 High Pressure Carbon Dioxide Pump

Supercritical Fluid Technologies, Inc. introduces the completely self-contained SFT-10 Liquid Carbon Dioxide Pump.  Advanced Peltier (thermoelectric) technology makes it possible to achieve high pressure without the need for an external cooling bath.

The SFT-10 pump can deliver carbon dioxide at pressures up to 10,000 psi (69 MPa) at flow rates from 0.01 to 24.0 ml/min.  These characteristics make the SFT-10 an ideal pump for use in supercritical fluid extraction, and a variety of other high pressure applications, including supercritical fluid reaction chemistry and chromatography.

The SFT-10 utilizes reliable, dual sapphire syringe pump technology to achieve high pressures rapidly. The Peltier chiller has superior cooling capability.  It maintains the temperature at the pump heads low enough to ensure the carbon dioxide remains liquid.

The standard operating mode is “constant pressure” where the pump will maintain a pressure set point.  An optional constant flow mode, from 0.01 to 24.0 ml/min., is available. 

The SFT-10 may be acquired as a stand alone CO2 pump or used as part of Supercritical Fluid Technologies’ SFT-110 / SFT-110XW Supercritical Fluid Extractors.


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

Tuesday 27 August 2013

Euroanalysis XVII #5

Professor Otto Wolfbeis is introduced and gives his plenary lecture entitled: Chemical Sensing and Biosensing Using Advanced Fluorescent (Nano)materials.

Euroanalysis XVII #4

Editor-in-Chief of Elsevier journal, Science of the Total Environment, Professor Damia Barcelo gives the opening presentation on the second day of the conference. Damia's talk is entitled: Analysis, Characterization, Fate and Behaviour of Nanomaterials in the Total Environment.


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:

Applications of in vivo and in vitro solid-phase microextraction techniques in plant analysis: A review

26 August 2013, 20:49:11
Publication date: 10 September 2013
Source:Analytica Chimica Acta, Volume 794
Author(s): Fang Zhu , Jianqiao Xu , Yuanyuan Ke , Siming Huang , Feng Zeng , Tiangang Luan , Gangfeng Ouyang
As a very popular sample preparation technique, solid-phase microextraction (SPME) coupled with various analytical instrumentation, has been widely used for the determination of trace levels of different plant compounds, such as volatile organic compounds (VOCs) emitted from the different plant organs, and environmental contaminants in plants. In this review, recent applications of in vitro and in vivo SPME in plant analysis are discussed and summarized according to the different organs of plants, including fruits, flowers, leaves, stems, roots and seeds, and the whole plant as well. Future developments and applications of SPME in plant analysis, especially in vivo sampling approaches, are also prospected.

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Determination of Pd, Rh, Pt, Au in road dust by electrothermal vaporization inductively coupled plasma mass spectrometry with slurry sampling

26 August 2013, 20:49:11
Publication date: 10 September 2013
Source:Analytica Chimica Acta, Volume 794
Author(s): Wan-Hsuan Hsu , Shiuh-Jen Jiang , A.C. Sahayam
Inductively coupled plasma mass spectrometry coupled with ultrasonic slurry sampling electrothermal vaporization (USS-ETV-ICP-MS) has been applied to determine Pd, Rh, Pt and Au in 0.5% m/v slurries of several road dust samples. 2% m/v ammonium pyrrolidine dithiocarbamate (APDC) was used as the modifier to enhance the ion count. The influence of instrument operating conditions, slurry preparation and interferences on the ion count was reported. This method has been applied to the determination of Pd, Rh, Pt and Au in BCR 723 Road Dust and NIST SRM 2709 San Joaquin Soil reference materials and two road dust samples collected locally. The analysis results of the standard reference materials agreed with the certified values. Precision between sample replicates was better than 10% for all the determinations. The method detection limits estimated from standard addition curves were 0.9, 0.4, 0.6 and 0.4ngg−1 for Pd, Rh, Pt and Au, respectively, in original dust samples.

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Extension and application of multivariate curve resolution-alternating least squares to four-way quadrilinear data-obtained in the investigation of pollution patterns on Yamuna River, India—A case study

26 August 2013, 20:49:11
Publication date: 10 September 2013
Source:Analytica Chimica Acta, Volume 794
Author(s): Amrita Malik , Roma Tauler
This study focuses on the development and extension of Multivariate Curve Resolution-Alternating Least Squares (MCR-ALS) to the analysis of four-way datasets. The proposed extension of the MCR-ALS method with non-negativity and the newly developed quadrilinear constraints can be exploited to summarize and manage huge multidimensional datasets and resolve their four way component profiles. In this study, its application is demonstrated by analyzing a four-way data set obtained in a long term environmental monitoring study (15 sampling sites×9 variables×12 months×7 years) belonging to the Yamuna River, one of the most polluted rivers of India and the largest tributary of the Ganges river. MCR-ALS resolved pollution profiles described appropriately the major observed changes on pH, organic pollution, bacteriological pollution and temperature, along with their spatial and temporal distribution patterns for the studied stretch of Yamuna River. Results obtained by MCR-ALS have also been compared with those obtained by another multi-way method, PARAFAC. The methodology used in this study is completely general and it can be applied to other multi-way datasets.

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Automatic identification of novel bacteria using Raman spectroscopy and Gaussian processes

26 August 2013, 20:49:11
Publication date: 10 September 2013
Source:Analytica Chimica Acta, Volume 794
Author(s): Michael Kemmler , Erik Rodner , Petra Rösch , Jürgen Popp , Joachim Denzler
Raman spectroscopy is successfully used for the reliable classification of complex biological samples. Much effort concentrates on the accurate prediction of known categories for highly relevant tasks in a wide area of applications such as cancer detection and bacteria recognition. However, the resulting recognition systems cannot always be directly used in practice since unseen samples might not belong to classes present in the training set. Our work aims to tackle this problem of novelty detection using a recently proposed approach based on Gaussian processes. By learning novelty scores for a large bacteria Raman dataset comprising 50 different strains, we analyze the behavior of this method on an independent dataset which includes known as well as unknown categories. Our experiment reveals that non-parametric methods such as Gaussian processes can be successfully applied to the task of finding unknown bacterial strains, leading to encouraging results motivating their further utilization in this area.

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Highlights


A novel magnetic poly(aniline-naphthylamine)-based nanocomposite for micro solid phase extraction of rhodamine B

26 August 2013, 20:49:11
Publication date: 10 September 2013
Source:Analytica Chimica Acta, Volume 794
Author(s): Habib Bagheri , Rasoul Daliri , Ali Roostaie
A novel Fe3O4–poly(aniline-naphthylamine)-based nanocomposite was synthesized by chemical oxidative polymerization process as a magnetic sorbent for micro solid phase extraction. The scanning electron microscopy images of the synthesized nanocomposite revealed that the copolymer posses a porous structure with diameters less than 50nm. The extraction efficiency of this sorbent was examined by isolation of rhodamine B, a mutagenic and carcinogenic dye, from aquatic media in dispersion mode. Among different synthesized polymers, Fe3O4/poly(aniline-naphthylamine) nanocomposite showed a prominent efficiency. Parameters including the desorption solvent, amount of sorbent, desorption time, sample pH, ionic strength, extraction time and stirring rate were optimized. Under the optimum condition, a linear spiked calibration curve in the range of 0.35–5.00μgL−1 with R 2 =0.9991 was obtained. The limits of detection (3S b) and limits of quantification (10S b) of the method were 0.10μgL−1 and 0.35μgL−1 (n =3), respectively. The relative standard deviation for water sample with 0.5μgL−1 of RhB was 4.2% (n =5) and the absolute recovery was 92%. The method was applied for the determination of rhodamine B in dishwashing foam, dishwashing liquid, shampoo, pencil, matches tips and eye shadows samples and the relative recovery percentage were in the range of 94–99%.

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A sensitive flow-batch system for on board determination of ultra-trace ammonium in seawater: Method development and shipboard application

26 August 2013, 20:49:11
Publication date: 10 September 2013
Source:Analytica Chimica Acta, Volume 794
Author(s): Yong Zhu , Dongxing Yuan , Yongming Huang , Jian Ma , Sichao Feng
Combining fluorescence detection with flow analysis and solid phase extraction (SPE), a highly sensitive and automatic flow system for measurement of ultra-trace ammonium in open ocean water was established. Determination was based on fluorescence detection of a typical product of o-phthaldialdehyde and ammonium. In this study, the fluorescence reaction product could be efficiently extracted onto an SPE cartridge (HLB, hydrophilic–lipophilic balance). The extracted fluorescence compounds were rapidly eluted with ethanol and directed into a flow cell for fluorescence detection. Compared with the common used fluorescence method, the proposed one offered the benefits of improved sensitivity, reduced reagent consumption, negligible salinity effect and lower cost. Experimental parameters were optimized using a univariate experimental design. Calibration curves, ranging from 1.67 to 300nM, were obtained with different reaction times. The recoveries were between 89.5 and 96.5%, and the detection limits in land-based and shipboard laboratories were 0.7 and 1.2nM, respectively. The relative standard deviation was 3.5% (n =5) for an aged seawater sample spiked with 20nM ammonium. Compared with the analytical results obtained using the indophenol blue method coupled to a long-path liquid waveguide capillary cell, the proposed method showed good agreement. The method had been applied on board during a South China Sea cruise in August 2012. A vertical profile of ammonium in the South East Asia Time-Series (SEATS, 18° N, 116° E) station was produced. The distribution of ammonium in the surface seawater of the Qiongdong upwelling in South China Sea is also presented.

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Matrix-assisted laser desorption ionization mass spectrometry for identification of shrimp

26 August 2013, 20:49:11
Publication date: 10 September 2013
Source:Analytica Chimica Acta, Volume 794
Author(s): Venkatesulu Salla , Kermit K. Murray
Matrix-assisted laser desorption ionization (MALDI) time of flight mass spectrometry was used to identify shrimp at the species level using commercial mass spectral fingerprint matching software (Bruker Biotyper). In the first step, a mass spectrum reference database was constructed from the analysis of six commercially important shrimp species: Litopenaeus setiferus, Farfantepenaeus aztecus, Sicyonia brevirostris, Pleoticus robustus, Pandalopsis dispar and Pandalus platyceros. This step required a desalting procedure for optimum performance. In the second step, the reference database was tested using 74 unknown shrimp samples from these six species. Correct identification was achieved for 72 of 74 samples (97%): 72 samples were identified at the species level and 2 samples were identified at the genus level using the manufacturer's log score specifications. The MALDI fingerprinting method for the identification of shrimp species was found to be reproducible and accurate with rapid analysis.

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Nottingham Further Invest In Green Chemistry Laboratory

The School of Chemistry at the University of Nottingham (UK) has placed a sizeable order with Asynt to upgrade their undergraduate teaching facilities with DrySyn Scholar Plus heating block systems.

The School of Chemistry at the University of Nottingham (www.nottingham.ac.uk/chemistry/index.aspx) is one of the leading Chemistry departments in the UK and is recognised internationally for its world leading research portfolio, excellence in teaching and extensive engagement with Industry. Its expertise spans the spectrum of modern chemical technology including synthesis, analysis and characterisation, ranging from the core chemistry disciplines to areas at the interface with biological sciences and engineering (sustainable chemical processing). In 2012 GlaxoSmithKline (GSK) and The University of Nottingham formalised a collaboration to establish a new laboratory to accommodate a Centre of Excellence for sustainable chemistry, and to construct an innovative carbon neutral sustainable chemistry facility.

David Chambers-Asman, Director of Operations & Administration at the School of Chemistry commented 'In line with Nottingham's commitment to develop ‘green and sustainable’ chemistry methodologies, we wanted to find a safe, more environmentally friendly alternative to heated oil baths for our undergraduates to learn about organic synthesis'.

He added 'After reviewing the market we elected to invest in Asynt DrySyn Scholar heating block systems because of their robustness, enhanced operator safety features and ease-of-use - making them the ideal for our organic synthesis'. 'As we teach hundreds of students in each year of our undergraduate Chemistry courses using, heated oil baths presented a risk to our students (through accidental spillage) and involved periodic requirement to dispose of large quantities of oil - a risk and environmental burden eliminated by using the DrySyn Scholar Plus'.

Specifically designed for safety conscious teaching laboratories - the DrySyn Scholar Plus kit enables single 50ml, 100ml or 250ml round bottom flask reactions to be performed safely without the mess or inherent hazards of a hot oil bath or heating mantle. Prominent permanently fixed lifting handles ensure moving even hot reaction blocks are easy, fast and safe. Compatible with almost any magnetic hotplate stirrer, the low thermal mass design of the DrySyn Scholar minimises both power consumption and reaction heat-up time.


Monday 26 August 2013

Euroanalysis XVII #3

Mikhail Proskurnin gives his presentation: Coupling Photometric Reactions and Signal Enhancement In Disperse Solutions for the Analysis of Technological and Biomedical Materials by Photothermal Spectroscopy

Euroanalysis XVII #2

Juergen Popp receiving the certificate to commemorate his Robert Kellner Lecture (see previous post).


Euroanalysis XVII #1

The conference got underway in Warsaw this morning and following a very interesting presentation by Adam Hulanicki on the history of Polish analytical chemistry, Analytica Chimica Acta editor, Professor Paul Worsfold, gave a laudation to Juergen Popp - recipient of the Robert Kellner Award.
Paul giving his laudation

Juergen Popp takes the stage to thank the assembled delegates and committee for his award before delivering a presentation entitled: The Many Facets of Raman Spectroscopy for Biomedical Analysis.
Juergen Popp

Training Course in Preparing Stable Lyophilized Protein Formulations

SP Scientific has announced a new hands-on training course entitled 'Rapid and Rational Development of Stable Lyophilized Protein Formulations'.

Due to take place from September 17-20, 2013 the extended training course has been designed by renowned industry experts Dr Jeff Schwegman** and Dr John Carpenter** to provide valuable assistance to those involved in the development and manufacture of diagnostics, vaccines, and biologically based injectable drug products including monoclonal antibodies.

Today an increasing number of products being developed as vaccines,diagnostics, and injectable drugs are based upon biological molecules such asproteins, enzymes, and antibodies.  Companies involved in these markets use these molecules to develop testing kits to detect various disease states and their pre-cursers, to develop vaccines to prevent and or minimize infections and to develop protein based drugs, including monoclonal antibodies,to treat disease states in both humans and animals.  While discovery and development of these types of products has soared, traditional downstream development methodologies used in formulation and stabilization are often failing to achieve long term stability, consequently companies may find themselves unable to manufacture their products to meet the guidelines laid out by the FDA.

Lyophilization, or freeze-drying, is recognized as a process used to enhance the stability of many products; however, if not done properly on biologically based formulations, it can be extremely damaging to the physical structure of the molecule, rendering them inactive, aggregated, and potentially eliciting an immune response in patients. Addressing this issue, the 4-day training coursehas been designed to enable people involved with lyophilisation, at all levels of experience, to gain considerable knowledge about the rapid and rational development of stable lyophilized protein formulations and to reinforce their classroom training with extensive laboratory work.

Full details of this extensive hands-on training course to be held in SP Scientific's modern Warminster, PA laboratory / training facility is available at www.spscientific.com/ProteinHandsOn.

Thursday 15 August 2013

Just Published: Chemometrics and Intelligent Laboratory Systems

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:
Chemometrics and Intelligent Laboratory Systems
http://rss.sciencedirect.com/publication/science/5232

Selected papers from the latest issue:

A real-time hyper-accuracy integrative approach to peak identification using lifting-based wavelet and Gaussian model for field mobile mass spectrometer

15 August 2013, 10:18:44
Publication date: 15 October 2013
Source:Chemometrics and Intelligent Laboratory Systems, Volume 128
Author(s): Cuiping Li , Jiuqiang Han , Qibin Huang , Ning Mu , Baoqiang Li , Bingqing Cao
Field mobile mass spectrometer is pivotal apparatus for real-time qualitative and quantitative analyses of chemical substances in situ environment pollution detection. To solve spectrum peak signal interfered by complicated noise, and to recognize irregular peak shape as well as quick monitoring, a real-time denoising and hyper-accuracy peak identification integrative approach for field mobile mass spectrometer using lifting-based wavelet transform (LWT) and Gaussian model has been developed. First, LWT was applied to eliminate the noise and to search for mass peak parameters in raw spectral peak data. Then, fitting the irregular mass peaks with Gaussian multi-peaks, a regular spectrum signal was obtained for further processing. Both of synthetic and apparatus experiment results show that LWT is a fast and effective denoising and peak identification method and retained the original peak features. The denoising effect (SNR/RMSE) by LWT was superior to Savitzky–Golay method used widely by experimental mass spectrometer, and the processing time was shortened obviously. Moreover integrated with Gaussian fitting algorithm, the peak parameters (the peak area A, centroid c, and half peak's width w) had been optimized. As the result, qualitative and quantitative accuracies of FMMS increased consequently. In addition, the approach achieved data compression.

Coefficient of variation, signal-to-noise ratio, and effects of normalization in validation of biomarkers from NMR-based metabonomics studies

15 August 2013, 10:18:44
Publication date: 15 October 2013
Source:Chemometrics and Intelligent Laboratory Systems, Volume 128
Author(s): Bo Wang , Aaron M. Goodpaster , Michael A. Kennedy
A primary goal of metabonomics research is biomarker discovery for human diseases based on differences in metabolic profiles between healthy and diseased patient populations. One of the most significant challenges in biomarker discovery is validation, which implicitly depends on the coefficient of variation (CV) associated with the measurement technique. This paper investigates how the CV of metabolite resonances measured by nuclear magnetic resonance spectroscopy (NMR) depends on signal-to-noise ratio (SNR) and normalization method. CVs were calculated for NMR resonance peaks in a series of NMR spectra of five synthetic urine samples collected over an eight-month period. An inverse correlation was detected between SNR and CV for all normalization methods. Small peaks with SNR<15 tended to have larger CVs (15–30%) compared to peaks with the highest SNR>150, which typically had smaller CVs (5–10%). The inverse relationship between CV and SNR roughly obeyed a log10 dependence. Quotient normalization (QN) tended to produce smaller CVs for smaller peaks, but larger CVs for the strongest peaks in the data, compared to no normalization, normalization to total intensity (NTI) or normalization to an internal standard (NIS). Consequently, quotient normalization appears optimal for validating low concentration metabolites. NTI or NIS appear superior to QN for samples that have very small variation in total signal intensity. While the inverse relationship between CV and log10(SNR) did not strictly hold for all metabolites, weaker concentration metabolites will likely require more rigorous validation as potential biomarkers since they tend to have poorer reproducibility.

Key wavelengths selection from near infrared spectra using Monte Carlo sampling–recursive partial least squares

15 August 2013, 10:18:44
Publication date: 15 October 2013
Source:Chemometrics and Intelligent Laboratory Systems, Volume 128
Author(s): Mingjin Zhang , Shizhi Zhang , Jibran Iqbal
Variable selection is a critical step in data analysis for near infrared spectroscopy. Recently, many studies have been reported on variable selection and researchers have proposed a large number of methods to identify variables (wavelengths) that contribute useful information. In the present study, a key wavelengths selection method named Monte Carlo sampling–recursive partial least squares (MCS-RPLS) is proposed. The method mainly includes three steps: (1) Monte Carlo sampling; (2) feature selection for each subset; and (3) determination of the optimum feature set for the dataset. The method has been used for feature selection and multivariate calibration on four near infrared spectroscopic datasets: corn moisture, corn protein, HSA and γ-globulin of biological samples. And the 10-fold cross validation results are compared with those obtained by full spectra-PLS, Moving Window Partial Least Squares (MWPLS), Monte Carlo-based Uninformative Variable Elimination (MC-UVE) and CARS. The results showed that the data dimensionalities and the RMSECV values of the selected variables are greatly reduced, thus the MCS-RPLS is available for feature selection from NIR data.
15 August 2013, 10:18:44
Publication date: 15 August 2013
Source:Chemometrics and Intelligent Laboratory Systems, Volume 127
Author(s): Andrés Mauricio Castillo , Lalita Uribe , Luc Patiny , Julien Wist
An efficient method to extract and store information from NMR spectra is proposed that is suitable for comparison and construction of a search engine. This method based on trees doesn't require any peak picking or any pre-treatment of the data and is found to outperform the currently available methods, both in terms of compactness and velocity. Our approach was tested for 1D proton spectra and 2D HSQC spectra and compared with the method proposed by Pretsch and coworkers [1,2] [Bodis et al. 2007, Bodis et al. 2009]. Additionally, the correspondence between spectral and structural similarity was evaluated for both methods.

Applications of a new empirical modelling framework for balancing model interpretation and prediction accuracy through the incorporation of clusters of functionally related variables

15 August 2013, 10:18:44
Publication date: 15 August 2013
Source:Chemometrics and Intelligent Laboratory Systems, Volume 127
Author(s): Marco S. Reis
Current classification and regression methodologies are strongly focused on maximizing prediction accuracy. Interpretation is usually relegated to a second stage, after model estimation, where its parameters and related quantities are scrutinized for relevant information regarding the process and phenomena under analysis. Network-Induced Supervised Learning (NI-SL) is a recently proposed framework that balances the goals of prediction accuracy and interpretation [1], by adopting a modelling formalism that matches more closely the dependency structure of variables in current complex systems. This framework computes interpretable features that are incorporated in the final model, which effectively constrain the predictive space to be used. However, this restriction does not compromise prediction ability, which quite often is enhanced. Both classification and regression problems can be handled. Four widely different real world datasets were used to illustrate the main features claimed for the NI-SL framework.

Multivariate Curve Resolution of incomplete data multisets

15 August 2013, 10:18:44
Publication date: 15 August 2013
Source:Chemometrics and Intelligent Laboratory Systems, Volume 127
Author(s): Marta Alier , Romà Tauler
In this paper the application of the Multivariate Curve Resolution Alternating Least Squares method (MCR-ALS) to incomplete data multisets is explored. The experimental incomplete data multiset studied in this work is taken from a previous multiannual atmospheric monitoring study of the changes of ozone and nitrogen oxide concentrations in an air quality sampling station located in the city of Barcelona, in which some of the individual data sets were missing. Based on the preliminary results obtained in this study, new data multisets, complete and incomplete, with different levels of noise were simulated and analysed by a new variant of the MCR-ALS method which optimises a combined error function including all possible complete data subsets derived from the original incomplete data multiset. Conclusions are drawn about the effects of data completeness on the results obtained for different noise levels and on the viability of trilinear models.

Graphical abstract

image

Highlights

Multivariate Curve Resolution is applied for the first time to incomplete data multisets. New data multisets, complete and incomplete, with different levels of noise were simulated and analysed by a new variant of the MCR-ALS method which optimises a combined error function including all possible complete data subsets derived from the original incomplete data multiset.