World Congress on Biosensors 2014

World Congress on Biosensors 2014
Biosensors 2014

Monday 5 November 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:

Preparation and evaluation of mesoporous cellular foams coating of solid-phase microextraction fibers by determination of tetrabromobisphenol A, tetrabromobisphenol S and related compounds

05 November 2012, 09:40:46
Publication year: 2012
Source:Analytica Chimica Acta, Volume 753
Xuemei Wang, Jiyan Liu, Aifeng Liu, Qian Liu, Xinzhen Du, Guibin Jiang
Two kinds of mesoporous cellular foams (MCFs), including mesoporous silica materials (MCF-1) and phenyl modified mesoporous materials (Ph-MCF-1), were synthesized and for the first time used as fiber-coating materials for solid-phase microextraction (SPME). By using stainless steel wire as the supporting core, four types of fibers were prepared by sol–gel method and immobilized by epoxy-resin method. To evaluate the performance of the home-made fibers for SPME, seven brominated flame retardants (BFRs), including tetrabromobisphenol A (TBBPA), tetrabromobisphenol S (TBBPS) and related compounds were selected as analytes. The main parameters that affect the extraction and desorption efficiencies, such as extraction temperature, extraction time, desorption time, stirring rate and ionic strength of samples were investigated and optimized. The optimized SPME coupled with high performance liquid chromatography (HPLC) was successfully applied to the determination of the seven BFRs in water samples. The linearity range was from 5.0 to 1000μgL−1 for each compound except TBBPS (from 1.0 to 1000μgL−1), with the correlation coefficients (r 2) ranging from 0.9993 to 0.9999. The limits of detection of the method were 0.4–0.9μgL−1. The relative standard deviations varied from 1.2 to 5.1% (n =5). The repeatability of fiber-to-fiber and batch-to-batch was 2.5–6.5% and 3.2–6.7%. The recoveries of the BFRs from aqueous samples were in the range between 86.5 and 103.6%. Compared with three commercial fibers (100μm PDMS, 85μm PA and 65μm PDMS/DVB), the MCFs-coated fiber showed about 3.5-fold higher extraction efficiency.

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Graphical abstract Highlights

► Two novel mesoporous cellular foams were synthesized and used as SPME coating. ► Four SPME fibers were prepared by sol–gel technology and immobilized resin method. ► New coating had excellent extraction ability to seven brominated flame retardants.

Review on recent advances in the analysis of isolated organelles

05 November 2012, 09:40:46
Publication year: 2012
Source:Analytica Chimica Acta, Volume 753
Chad P. Satori, Vratislav Kostal, Edgar A. Arriaga
The analysis of isolated organelles is one of the pillars of modern bioanalytical chemistry. This review describes recent developments on the isolation and characterization of isolated organelles both from living organisms and cell cultures. Salient reports on methods to release organelles focused on reproducibility and yield, membrane isolation, and integrated devices for organelle release. New developments on organelle fractionation after their isolation were on the topics of centrifugation, immunocapture, free flow electrophoresis, flow field-flow fractionation, fluorescence activated organelle sorting, laser capture microdissection, and dielectrophoresis. New concepts on characterization of isolated organelles included atomic force microscopy, optical tweezers combined with Raman spectroscopy, organelle sensors, flow cytometry, capillary electrophoresis, and microfluidic devices.

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► Advancements in organelle release. ► New approaches to fractionate organelles. ► Updates on new techniques to characterize isolated organelles.

Discriminant analysis in the presence of interferences: Combined application of target factor analysis and a Bayesian soft-classifier

05 November 2012, 09:40:46
Publication year: 2012
Source:Analytica Chimica Acta, Volume 753
Caitlin N. Rinke, Mary R. Williams, Christopher Brown, Matthieu Baudelet, Martin Richardson, Michael E. Sigman
A method is described for performing discriminant analysis in the presence of interfering background signal. The method is based on performing target factor analysis on a data set comprised of contributions from analyte(s) and interfering components. A library of data from representative analyte classes is tested for possible contributing factors by performing oblique rotations of the principal factors to obtain the best match, in a least-squares sense, between test and predicted vectors. The degree of match between the test and predicted vectors is measured by the Pearson correlation coefficient, r, and the distribution of r for each class is determined. A Bayesian soft classifier is used to calculate the posterior probability based on the distributions of r for each class, which assist the analyst in assessing the presence of one or more analytes. The method is demonstrated by analyses performed on spectra obtained by laser induced breakdown spectroscopy (LIBS). Single and multiple bullet jacketing transfers to steel and porcelain substrates were analyzed to identify the jacketing materials. Additionally, the metal surrounding bullet holes was analyzed to identify the class of bullet jacketing that passed through a stainless steel plate. Of 36 single sample transfers, the copper jacketed (CJ) and non-jacketed (NJ) class on porcelain had an average posterior probability of the metal deposited on the substrate of 1.0. Metal jacketed (MJ) bullet transfers to steel and porcelain were not detected as successfully. Multiple transfers of CJ/NJ and CJ/MJ on the two substrates resulted in posterior probabilities that reflected the presence of both jacketing materials. The MJ/NJ transfers gave posterior probabilities that reflected the presence of the NJ material, but the MJ component was mistaken for CJ on steel, while non-zero probabilities were obtained for both CJ and MJ on porcelain. Jacketing transfer from a bullet to steel as the projectile passed through the steel also proved difficult to analyze. Over 50% of the samples left insufficient transfer to be identified. Transfer from NJ and CJ jacketing was successfully identified by posterior probabilities greater than 0.8.

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Graphical abstract Highlights

► A novel background-independent soft classification method is described. ► Target factor analysis is combined with Bayesian decision theory. ► Target factors are taken from a library of target analytes. ► Trace metal transfers to complex backgrounds are analyzed by LIBS. ► The method is shown to be both conservative and accurate.

Ultrasensitive one-step rapid detection of ochratoxin A by the folding-based electrochemical aptasensor

05 November 2012, 09:40:46
Publication year: 2012
Source:Analytica Chimica Acta, Volume 753
Jingjing Wu, Huaqin Chu, Zhanlong Mei, Yi Deng, Feng Xue, Lei Zheng, Wei Chen
A one-step electrochemical aptasensor using the thiol- and methylene blue- (MB-) dual-labeled aptamer modified gold electrode for determination of ochratoxin A (OTA) was presented in this research. The aptamer against OTA was covalently immobilized on the surface of the electrode by the self-assembly effect and used as recognition probes for OTA detection by the binding induced folding of the aptamer. Under the optimal conditions, the developed electrochemical aptasensor demonstrated a wide linear range from 0.1pgmL−1 to 1000pgmL−1 with the limit of detection (LOD) of 0.095pgmL−1, which was an extraordinary sensitivity compared with other common methods for OTA detection. Moreover, as a practical application, this proposed electrochemical aptasensor was used to monitor the OTA level in red wine samples without any special pretreatment and with satisfactory results obtained. Study results showed that this electrochemical aptasensor could be a potential useful platform for on-site OTA measurement in real complex samples.

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► One-step electrochemical aptasensor for OTA detection. ► Rapid and ultrasensitive OTA detection with LOD of 0.095pgmL−1 in less than 15min. ► Successful application of the electrochemical aptasensor in OTA spiked samples. ► Providing a potential tool for on-site quality control of OTA related pollutions.

Layer by layer assembly of catalase and amine-terminated ionic liquid onto titanium nitride nanoparticles modified glassy carbon electrode: Study of direct voltammetry and bioelectrocatalytic activity

05 November 2012, 09:40:46
Publication year: 2012
Source:Analytica Chimica Acta, Volume 753
Shagayegh Saadati, Abdollah Salimi, Rahman Hallaj, Amin Rostami
A novel, simple and facile layer by layer (LBL) approach is used for modification of glassy carbon (GC) electrode with multilayer of catalase and nanocomposite containing 1-(3-Aminopropyl)-3-methylimidazolium bromide (amine terminated ionic liquid (NH2-IL)) and titanium nitride nanoparticles (TiNnp). First a thin layer of NH2-IL is covalently attached to GC/TiNnp electrode using electro-oxidation method. Then, with alternative self assemble positively charged NH2-IL and negatively charged catalase a sensitive H2O2 biosensor is constructed, whose response is directly correlated to the number of bilayers. The surface coverage of active catalase per bilayer, heterogeneous electron transfer rate constant (k s) and Michaelis–Menten constant (K M) of immobilized catalase were 3.32×10−12 molcm−2, 5.28s−1 and 1.1mM, respectively. The biosensor shows good stability, high reproducibility, long life-time, and fast amperometric response with the high sensitivity of 380μAmM−1 cm−2 and low detection limit of 100nM at concentration range up to 2.1mM.

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Graphical abstract Highlights

► Catalase and amine-terminated ionic liquid were immobilized to GC/TiNnp with LBL assembly method. ► First a thin layer of NH2-IL is covalently attached to GC/TiNnp electrode using electro-oxidation. ► With alternative assemble of IL and catalase with positive and negative charged, multilayer was formed. ► Immobilized catalase shows excellent electrocatalytic activity toward H2O2 reduction. ► Biosensor response is directly correlated to the number of bilayers.

Sulfide determination in hydrothermal seawater samples using a vibrating gold micro-wire electrode in conjunction with stripping chronopotentiometry

05 November 2012, 09:40:46
Publication year: 2012
Source:Analytica Chimica Acta, Volume 753
Virginie Aumond, Matthieu Waeles, Pascal Salaün, Kristoff Gibbon-Walsh, Constant M.G. van den Berg, Pierre-Marie Sarradin, Ricardo D. Riso
A rapid electrochemical stripping chronopotentiometric procedure to determined sulfide in unaltered hydrothermal seawater samples is presented. Sulfide is deposited at −0.25V (vs Ag/AgCl, KCl 3M) at a vibrating gold microwire and then stripped through the application of a reductive constant current (typically −2μA). The hydrodynamic conditions are modulated by vibration allowing a short deposition step, which is shown here to be necessary to minimize H2S volatilization. The limit of detection (LOD) is 30nM after a deposition step of 7s. This LOD is in the same range as the most sensitive cathodic voltammetric technique using a mercury drop electrode and is well below those reported previously for other electrodes capable of being implemented in situ.

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Halogen bonding: A new retention mechanism for the solid phase extraction of perfluorinated iodoalkanes

05 November 2012, 09:40:46
Publication year: 2012
Source:Analytica Chimica Acta, Volume 753
Xiao Qing Yan, Qian Jin Shen, Xiao Ran Zhao, Hai Yue Gao, Xue Pang, Wei Jun Jin
For the first time, halogen-bonding interaction is utilised in the solid phase extraction of perfluorinated iodoalkane (PFI). Nine PFIs, as model analytes, were tested, and analyses by UV, 19F NMR and Raman spectroscopies demonstrate that the PFIs are extracted by a strong anion exchange (SAX) sorbent from n-hexane due to the CI⋯Cl halogen-bonding interactions. The results also show that the adsorptivities of SAX for the diiodoperfluoro-alkanes (diiodo-PFIs) were much stronger than those for the perfluoroalkyl iodides (monoiodo-PFIs). Specifically, the recoveries for 1,6-diiodoperfluorohexane and 1,8-diiodoperfluorooctane were higher than 80% when 100mL of sample spiked with a 5ngmL−1 analyte mixture was extracted. Interestingly, SAX had no adsorption for hexafluorobenzene at all, which is known to be unable to form a halogen bond with Cl. The analytical performance of the halogen bond-based SPE-GC–MS method for the diiodo-PFIs was also examined in soil samples. The sorbent SAX enabled the selective extraction of four diiodo-PFIs successfully from soil samples. The recoveries of the diiodo-PFIs extracted from 5g soil sample at the 100ngg−1 spike level were in the range of 73.2–93.8% except 26.8% for 1,2-diiodoperfluoroethane. The limit of detection varied from 0.02 to 0.04ngg−1 in soil samples. Overall, this work reveals the great application potential of halogen bonding in the field of solid phase extraction to selectively extract compounds with strong halogen-bonding abilities.

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Graphical abstract Highlights

► Halogen bonding (XB) is firstly utilised in solid phase extraction. ► The perfluorinated iodine alkanes can be extracted by CI⋯Cl halogen bonding. ► The CI⋯Cl halogen bond is well characterised by spectroscopy methods. ► The analytes with strong halogen-bonding abilities can be selectively extracted.

Determination of hydroxylated metabolites of polycyclic aromatic hydrocarbons in sediment samples by combining subcritical water extraction and dispersive liquid–liquid microextraction with derivatization

05 November 2012, 09:40:46
Publication year: 2012
Source:Analytica Chimica Acta, Volume 753
Xiaowei Wang, Li Lin, Tiangang Luan, Lihua Yang, Nora F.Y. Tam
A sample preparation method for the determination of hydroxylated polycyclic aromatic hydrocarbons (OH-PAHs) in sediment samples was developed using gas chromatography–mass spectrometry (GC–MS). Dispersive liquid–liquid microextraction (DLLME) with derivatization was performed following the subcritical water extraction (SWE) that provided which was provided by accelerated solvent extraction (ASE). Several important parameters that affected both SWE extraction and DLLME, such as the selection of organic modifier, its volume, extraction temperature, extraction pressure and extraction time were also investigated. High sensitivity of the hydroxylated PAHs derivatives by N-(tert-butyldimethylsilyl)-N-methyl-trifluoroacetamide (MTBSTFA) could be achieved with the limits of detection (LODs) ranging from 0.0139 (2-OH-nap) to 0.2334μgkg−1 (3-OH-fluo) and the relative standard deviations (RSDs) between 2.81% (2-OH-phe) and 11.07% (1-OH-pyr). Moreover, the proposed method was compared with SWE coupled with solid phase extraction (SPE), and the results showed that ASE–DLLME was more promising with recoveries ranging from 57.63% to 91.07%. The proposed method was then applied to determine the hydroxylated metabolites of phenanthrene in contaminated sediments produced during the degradation by two PAH-degraders isolated from mangrove sediments.

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Graphical abstract Highlights

► We combine subcritical water extraction (SWE) with dispersive liquid–liquid microextraction (DLLME). ► Subcritical water is used as the extraction solvent for SWE and the sample solution for the following DLLME. ► Acetonitrile is used as the organic modifier for SWE and disperser solvent for DLLME in succession. ► We examine changes of OH-PAHs during the degradation by microorganism.

Highly specific revelation of rat serum glycopeptidome by boronic acid-functionalized mesoporous silica

05 November 2012, 09:40:46
Publication year: 2012
Source:Analytica Chimica Acta, Volume 753
Liting Liu, Ying Zhang, Lei Zhang, Guoquan Yan, Jun Yao, Pengyuan Yang, Haojie Lu
Although the specific profiling of endogenous glycopeptides in serum is highly inclined towards the discovery of disease biomarkers, studies on the endogenous glycopeptides (glycopeptidome) have never been conducted because of several factors. These factors include the high dynamic range of serum proteins, the inadequacy of traditional sample preparation techniques in proteomics for low-molecular-weight (LMW) proteins, and the relatively low abundances of glycopeptides. Boronic acid-functionalized mesoporous silica was synthesized in this study to overcome the limitations of the state-of-the-art methods for glycopeptidome research. The boronic acid-functionalized mesoporous silica exhibited excellent selectivity by analyzing glycopeptides in the mixture of glycopeptides/non-glycopeptides at molar ratio of 1:100, extreme sensitivity (the limit of detection was at the fmol level), good binding capacity (40mgg−1), as well as the high post-enrichment recovery of glycopeptides (up to 88.10%). The as-prepared material possessing both glycopeptide-suitable pore size and glycopeptide-specific selectivity has shown special capability for enriching the endogenous glycopeptides. Fifteen unique glycosylation sites mapped to 15 different endogenous glycopeptides were identified in rat serum. The established protocol revealed for the first time the rat serum glycopeptidome.

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Graphical abstract Highlights

A highly ordered boronic acid-functionalized mesoporous silica was synthesized and applied for the revelation of rat serum glycopeptidome for the first time.
► A highly ordered boronic acid-functionalized mesoporous silica was synthesized. ► The as-prepared material possessed both glycopeptide-suitable pore size and glycopeptide-specific selectivity. ► The as-prepared material showed highly efficient ability for enrichment of endogenous glycopeptides from serum. ► Rat serum glycopeptidome was reveled for the first time.

Rapid differentiation of Panax ginseng and Panax quinquefolius by matrix-assisted laser desorption/ionization mass spectrometry

05 November 2012, 09:40:46
Publication year: 2012
Source:Analytica Chimica Acta, Volume 753
Ying-Han Lai, Pui-Kin So, Samual Chun-Lap Lo, Eddy Wing Yin Ng, Terence Chuen Wai Poon, Zhong-Ping Yao
A matrix-assisted laser desorption/ionization mass spectrometry (MALDI-MS)-based method has been developed for rapid differentiation between Panax ginseng and Panax quinquefolius, two herbal medicines with similar chemical and physical properties but different therapeutic effects. This method required only a small quantity of samples, and the herbal medicines were analyzed by MALDI-MS either after a brief extraction step, or directly on the powder form or small pieces of raw samples. The acquired MALDI-MS spectra showed different patterns of ginsenosides and small chemical molecules between P. ginseng and P. quinquefolius, thus allowing unambiguous differentiation between the two Panax species based on the specific ions, intensity ratios of characteristic ions or principal component analysis. The approach could also be used to differentiate red ginseng or P. quinquefolius adulterated with P. ginseng from pure P. ginseng and pure Panax quinquefolium. The intensity ratios of characteristic ions in the MALDI-MS spectra showed high reproducibility and enabled quantitative determination of ginsenosides in the herbal samples and percentage of P. quinquefolius in the adulterated binary mixture. The method is simple, rapid, robust, and can be extended for analysis of other herbal medicines.

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Graphical abstract Highlights

► Rapid differentiation of Panax ginseng and Panax quinquefolius by MALDI-MS. ► Direct analysis of raw herbal samples by MALDI-MS. ► Identification of adulterated Panax quinquefolius. ► Quantitative measurements of ginsenosides and compositions of Panax ginseng and Panax quinquefolius mixtures.

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