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World Congress on Biosensors 2014
Biosensors 2014
Thursday, 4 October 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:
Publication year:
2012 Source:Analytica Chimica Acta, Volume 749 Guo-Jun Zhang, Yong
Ning Over the past decade, silicon nanowire (SiNW) biosensors have been
studied for the detection of biological molecules as highly sensitive,
label-free, and electrical tools. Herein we present a comprehensive review about
the fabrication of SiNW biosensors and their applications in disease
diagnostics. We discuss the detection of important biomarkers related to
diseases including cancer, cardiovascular diseases, and infectious diseases.
SiNW biosensors hold great promise to realize point-of-care (POC) devices for
disease diagnostics with potential for miniaturization and integration.
Graphical abstract
Graphical abstract Highlights
A typical SiNW FET-based
biosensor for detecting biomolecules. ► SiNW
biosensor has been developed as a sensitive, label-free, electrical tool. ► SiNW
biosensor has been applied to the detection of important biomarkers. ► SiNW
biosensor shows a potential of miniaturization and integration. ► SiNW biosensor
indicates a promising POC device for disease diagnostics. ► The diseases can
include cancer, cardiovascular disease, and infectious disease.
Publication year:
2012 Source:Analytica Chimica Acta, Volume 749 C. Herrero Latorre,
J. Álvarez Méndez, J. Barciela García, S. García Martín, R.M. Peña
Crecente New materials have significant impact on the development of new
methods and instrumentation for chemical analysis. From the discovery of carbon
nanotubes in 1991, single and multi-walled carbon nanotubes – due to their high
adsorption and desorption capacities – have been employed as sorption substrates
in solid-phase extraction for the preconcentration of metal species from diverse
matrices. Looking for successive improvements in sensitivity and selectivity, in
the past few years, carbon nanotubes have been utilized as sorbents for solid
phase extraction in three different ways: like as-grown, oxidized and
functionalized nanotubes. In the present paper, an overview of the recent trends
in the use of carbon nanotubes for solid phase extraction of metal species in
environmental, biological and food samples is presented. The determination
procedures involved the adsorption of metals on the nanotube surface, their
quantitative desorption and subsequent measurement by means of atomic
spectrometric techniques such as flame atomic absorption spectrometry,
electrothermal atomic absorption spectrometry or inductively coupled plasma
atomic emission spectrometry/mass spectrometry, among others. Synthesis,
purification and types of carbon nanotubes, as well as the diverse chemical and
physical strategies for their functionalization are described. Based on 140
references, the performance and general properties of the applications of solid
phase extraction based on carbon nanotubes for metal species atomic
spectrometric determination are discussed.
Graphical abstract
Graphical abstract Highlights
►
The use of CNTs as sorbent for metal species in solid phase extraction has been
described. ► Physical and chemical strategies for functionalization of carbon
nanotubes have been discussed. ► Published analytical methods concerning solid
phase extraction and atomic spectrometric determination have been
reviewed.
Publication year:
2012 Source:Analytica Chimica Acta, Volume 749 A. Fuentes-Cid, J.
Villanueva-Alonso, E. Peña-Vázquez, P. Bermejo-Barrera The objective of this
study is to evaluate the performance of two lab-made systems based on the
Multimode Introduction System (MSIS™) and the modified MSIS™, to generate and
introduce vapors of Ag, Cu, Cd, Cu, Ni, Sn, Zn, and also Au in the ICP torch. An
univariate procedure was used to select the optimized working conditions (Ar
flow, sample, reductant and waste flows, and reagent concentrations). Optimum
conditions for working with modified MSIS were: nitric acid concentration 0.35M,
8-hydroxyquinoline concentration: 40mgL−1, sodium borohydride
concentration: 1.75% (w/v)+0.4% (w/v) NaOH, argon purge flow to sweep the vapors
to the torch: 1.2Lmin−1, sample flow and sodium borohydride flows:
2.3Lmin−1; waste flow: 7.7mLmin−1. For the optimum working
conditions for lab-made MSIS in dual mode the concentration of
8-hydroxyquinoline was 225mgL−1, the Ar purge flow was
0.75Lmin−1, and the conventional nebulization flow was
2.3Lmin−1. The sensitivity obtained was higher using the lab-made
MSIS than using the lab-made modified MSIS or a forced outlet gas–liquid
separator. The limits of detection were better for Au, Cd, Sn than those
obtained using conventional nebulization; the measurements were precise (RSDs≤5%
in dual mode) and a good accuracy was obtained in the determination of Cd, Cu,
Ni and Zn in a wastewater reference material using aqueous calibration and the
lab-made MSIS in dual mode.
Graphical abstract
Graphical abstract Highlights
►
Two lab-made systems based on MSIS™ were evaluated to generate vapors of Ag, Au,
Cd, Cu, Ni, Sn and Zn. ► The present study provides data about Au in a dual-mode
sample-introduction system. ► The two systems were compared with the use of a
forced outlet gas–liquid separator and conventional nebulization. ► The LODs
were lower for Au, Cd and Sn using lab-made MSIS working in dual mode. ►
8-Hydroxyquinoline was used to improve volatilization, and detection was
performed by ICPOES.
Publication year:
2012 Source:Analytica Chimica Acta, Volume 749 Vinod Kumar Gupta,
Ashok Kumar Singh, Naveen Mergu Beryllium(II) selective electrodes have been
fabricated based on poly(vinyl chloride) (PVC) matrix membranes containing newly
synthesized neutral carrier dibenzo(perhydrotriazino)aza-14-crown-4 ethers as
ionophore. Best performance was exhibited by the membrane having a composition
ionophore (IIa):PVC:sodium tetraphenylborate (NaTPB):tributyl phosphate (TBP) in
the ratio (w/w; mg) of 5:30:3:65. This membrane worked well over a wide
concentration range 7.6×10−6 to 1.0×10−1 M of
Be2+ with a Nernstian slope of 30.7mV per decade of beryllium
activity. The response time of the sensor is 15s and the membrane can be used
over a period of 4months with good reproducibility. The proposed electrode works
well in a wide pH range 3.0–9.0. It was successfully applied to the
determination of beryllium in a mineral sample.
Graphical abstract
Graphical abstract Highlights
Variation of potential with
Be2+ activity for membrane sensors based on
dibenzo(perhydrotriazino)aza-14-crown-4 ether. ► It
is the first report on an ion sensor using substituted aza-14-crown-4 for
Be2+. ► Response time is 15s and life time is more than 4months with
good reproducibility. ► The proposed electrode works well in a wide pH range
3.0–9.0.
Publication year:
2012 Source:Analytica Chimica Acta, Volume 749 Steve Janagap, Rita
Azeredo, Thu-Thao Nguyen, Kristin Hamre, Pedro Araujo A simple extraction
method for the analysis of PGE2 and PGF2α in gonad samples from Atlantic cod and
further quantification by using liquid chromatography–tandem mass spectrometry
is proposed. The evaluation of the best solvent extraction conditions and the
analytical performance parameters are reported. The method was highly selective
for both prostaglandins and the calibration curves, based on the internal
standard method, were linear between 5 and 1000ngmL−1 for PGE2 and
PGF2α, with limits of detection of 1ngmL−1 and 1.5ngmL−1
and recovery values of 99.999±0.002 and 99.967±0.023 respectively. The
homogenization of samples using liquid nitrogen combined with the developed
extraction protocol can be implemented in different types of biological tissues.
Graphical abstract
Graphical abstract Highlights
►
Novel method for extraction of prostaglandins from fish gonads using LC–MS/MS. ►
Key features: low sample and solvent consumption and high sample throughput. ►
The method is a better alternative to ELISA generally used in reproduction
studies.
Publication year:
2012 Source:Analytica Chimica Acta, Volume 749 Ting Wen, Fei Qu,
Nian Bing Li, Hong Qun Luo In this work, we utilized polyethyleneimine-capped
silver nanoclusters (PEI-Ag nanoclusters) to develop a new fluorometric method
for the determination of hydrogen peroxide and glucose with high sensitivity.
The PEI-Ag nanoclusters have an average size of 2nm and show a blue emission at
455nm. The photostable properties of the PEI-Ag nanoclusters were examined. The
fluorescence of the PEI-Ag nanoclusters could be particularly quenched by H2O2.
The oxidization of glucose by glucose oxidase coupled with the fluorescence
quenching of PEI-Ag nanoclusters by H2O2 can be used to detect glucose. Under
optimum conditions, the fluorescence intensity quenched linearly in the range of
500nM–100μM with high sensitivity. The detection limit for H2O2 was 400nM. And a
linear correlation was established between fluorescence intensity (F 0 − F) and
concentration of glucose in the range of 1.0×10−6 to
1.0×10−5 M and 1.0×10−5 to 1.0×10−3 M with a
detection limit of 8.0×10−7 M. The method was used for the detection
of glucose in human serum samples with satisfactory results. Furthermore, the
mechanism of sensitive fluorescence quenching response of Ag nanoclusters to
glucose and H2O2 has been discussed.
Graphical abstract
Graphical abstract Highlights
► A
new method for synthesis of Ag nanoclusters using polyethyleneimine as a
stabilizing agent was developed. ► Water-soluble Ag nanoclusters possessed high
fluorescence and excellent biocompatibility. ► A new approach for determination
of glucose and H2O2 by fluorescence quenching was developed. ► The method for
detecting glucose and H2O2 has high sensitivity, low toxicity, and easy
operation. ► Ag nanoclusters has great potential for bioimaging.
Publication year:
2012 Source:Analytica Chimica Acta, Volume 749 Igor Jancan, Megan
A. Macnaughtan The acid dissociation constant (pK a) of small, biological
molecules is an important physical property used for investigating enzyme
mechanisms and inhibitor design. For phosphorus-containing molecules, the
31P nuclear magnetic resonance (NMR) chemical shift is sensitive to
the local chemical environment, particularly to changes in the electronic state
of the molecule. Taking advantage of this property, we present a 31P
NMR approach that uses inorganic phosphate buffer as an internal pH reference to
determine the pK a values of the imide and second diphosphate of
uridine-5′-diphosphate compounds, including the first reported values for
UDP-GlcNAc and UDP-S-GlcNAc. New methods for using inorganic phosphate buffer as
an internal pH reference, involving mathematical correction factors and careful
control of the chemical shift reference sample, are illustrated. A comparison of
the newly determined imide and diphosphate pK a values of UDP, UDP-GlcNAc, and
UDP-S-GlcNAc with other nucleotide phosphate and thio-analogs reveals the
significance of the monosaccharide and sulfur position on the pK a values.
Graphical abstract
Graphical abstract Highlights
►
The first reported phosphate and imide pK a values of UDP-GlcNAc and
UDP-S-GlcNAc. ► New role for the monosaccharide in the imide pK a of
uridine-5′-phosphate compounds. ► UDP-S-GlcNAc and UDP-GlcNAc have the same
phosphate pK a, unlike thioyl analogs. ► The 31P chemical shift of
inorganic phosphate is a viable internal pH reference. ► Stability of the
external 31P chemical shift reference is essential.
Publication year:
2012 Source:Analytica Chimica Acta, Volume 749 Jing-Jing Liu,
Xiao-Rong Song, Yi-Wei Wang, Ai-Xian Zheng, Guo-Nan Chen, Huang-Hao Yang A
simple turn-on and homogeneous aptasensor, which relies on target induced
formation of silver nanoclusters (Ag NCs), was developed for the determination
of platelet-derived growth factor B-chain homodimer (PDGF-BB). The aptasensor
contains two hairpin DNA probes termed as P1 and P2. P1 consists of the aptamer
sequence of PDGF-BB. Meanwhile, P2 contains the Ag NCs nucleation sequence,
which is blocked by the hairpin stem region. P1 and P2 can co-exist metastably
in the absence of PDGF-BB and maintain hairpin structure. However, in the
presence of PDGF-BB, the binding of PDGF-BB with aptamer will result in the
hybridization between P1 and P2, and release the Ag NCs nucleation sequence. In
this case, Ag NCs can be formed via the reduction of Ag+ by NaBH4. By
monitoring the increase in fluorescence intensity, we could detect the target
protein with high sensitivity. The detection limit of this aptasensor is 0.37nM,
which is comparable with that of other reported aptasensors. Furthermore, this
proposed aptasensor shows high selectivity toward its target protein. Thus, the
proposed aptasensor based on target induced formation of Ag NCs could be used as
a sensitive and selective platform for the detection of target protein.
Graphical abstract
Graphical abstract Highlights
► A
turn-on aptasensor was developed via target induced silver nanoclusters
formation. ► This aptasensor exhibited high sensitivity and selectivity for
PDGF-BB detection. ► This aptasensor is capable of detecting PDGF-BB in real
samples. ► This aptasensor is label-free, making it more simple and cost
effective.
Publication year:
2012 Source:Analytica Chimica Acta, Volume 748 Jun Haginaka, Hiromi
Tabo, Hisami Matsunaga Monodisperse molecularly imprinted polymers (MIPs) for
diphenyl phosphate (DPP) and 1-naphthyl phosphate (1-NapP) have been prepared by
a multi-step swelling and polymerization method using 4-vinylpyridine as a
functional monomer, glycerol dimethacrylate as a crosslinker and cyclohexanol or
1-hexanol as a porogen. The retention and molecular-recognition properties of
these MIPs for organophosphorus compounds were evaluated by HPLC using a mixture
of phosphate buffer and acetonitrile as an eluent. In addition to shape
recognition, hydrogen bonding and hydrophobic interactions could play an
important role in the retention and molecular recognition of DPP and 1-NapP.
Furthermore, the MIPs were applied to the separation of adenosine and adenosine
phosphates (AMP, ADP and ATP). These phosphates were retained on the MIPs
according to the number of phosphate groups in the molecule and were well
separated from one another. Hydrogen bonding and hydrophobic interactions seemed
to affect the retention and recognition of adenosine phosphates in low
acetonitrile content, while hydrophilic interactions affected these properties
in high acetonitrile content. Finally, the MIPs were applied to the trapping of
phosphopeptides. The MIPs non-selectively trapped phosphopeptides, which have
phosphorylated tyrosine, serine or threonine in the sequences, and successfully
trapped four phosphopeptides in tryptic digests of bovine α-casein.
Graphical abstract
Graphical abstract Highlights
►
Monodisperse MIPs for organophosphates by multi-step swelling and
polymerization. ► Application of MIPs to the separation of adenosine phosphates.
► Application of MIPs to the trapping of phosphopeptides in tryptic
protein-digests.
Publication year:
2012 Source:Analytica Chimica Acta, Volume 748 Marek Roszko,
Małgorzata Rzepkowska, Arkadiusz Szterk, Krystyna Szymczyk, Renata Jędrzejczak,
Marcin Bryła Polychlorinated biphenyls (PCBs) and polybrominated diphenyl
ethers (PBDEs) are hazardous food contaminants, their maximum legally allowable
levels in food and environment are in the low pgg−1 range. Therefore
some highly selective and sensitive analytical methods must be used to determine
them. The 96/23/EC Directive implemented by EC Decision of 12 August 2002
requires recovery rate of an analyte at a concentration below 1ngg−1
within the 50–120% range at relative standard deviation (RSD) as low as
possible. A method to determine low level PCBs and PBDEs in milk fat based on
the semi-permeable membrane dialysis/ion trap GC MS technique was developed.
Validation experiments proved that the method performance was within bounds set
by the currently standing UE regulations. Recovery rates calculated on the basis
of labeled internal standards for majority of the studied indicator PCB
congeners and PBDE congeners were close to 100% at RSD below 20%. Also,
dioxin-like PCBs recovery rates were compatible with the 1883/2006 EC Regulation
(80–120%, RSD below 15%). The developed method turned out to be linear within a
far broader concentration range than the studied 0.0025–10pgμL−1
range entirely sufficient for analyses of PCB and PBDE in milk fat. Within that
range coefficient of linear correlation (R 2) of calibration curves
exceeded 0.98.
Graphical abstract
Graphical abstract Highlights
► We
have investigated the usefulness of SPM dialysis for determination of PCB/PBDE.
► The factors affecting the dialysis process were evaluated. ► The ion trap MS
was optimized for determination of PCB/PBDE in milk fat. ► Described
extraction/clean up method proves usefulness for the milk fat
analysis.
Publication year:
2012 Source:Analytica Chimica Acta, Volume 748 M.M. Parrilla
Vázquez, P. Parrilla Vázquez, M. Martínez Galera, M.D. Gil García An
ultrasound-assisted ionic liquid dispersive liquid–liquid microextraction
(US-IL-DLLME) procedure was developed for the extraction of eight
fluoroquinolones (marbofloxacin, norfloxacin, ciprofloxacin, lomefloxacin,
danofloxacin, enrofloxacin, oxolinic acid and nalidixic acid) in groundwater,
using high-performance liquid chromatography with fluorescence detection
(HPLC-FD). The ultrasound-assisted process was applied to accelerate the
formation of the fine cloudy solution using a small volume of disperser solvent
(0.4mL of methanol), which increased the extraction efficiency and reduced the
equilibrium time. For the DLLME procedure, the IL 1-octyl-3-methylimidazolium
hexafluorophosphate ([C8MIM] [PF6]) and methanol (MeOH) were used as extraction
and disperser solvent, respectively. By comparing [C8MIM] [PF6] with
1-hexyl-3-methylimidazolium hexafluorophosphate ([C6MIM] [PF6]) and
1-butyl-3-methylimidazolium hexafluorophosphate ([C4MIM] [PF6]) as extraction
solvents, it was observed that when using [C8MIM] [PF6] the cloudy solution was
formed more readily than when using [C6MIM] [PF6] or [C4MIM] [PF6]. The factors
affecting the extraction efficiency, such as the type and volume of ionic
liquid, type and volume of disperser solvent, cooling in ice-water, sonication
time, centrifuging time, sample pH and ionic strength, were optimised. A slight
increase in the recoveries of fluoroquinolones was observed when an ice-water
bath extraction step was included in the analytical procedure (85–107%) compared
to those obtained without this step (83–96%). Under the optimum conditions,
linearity of the method was observed over the range 10–300ngL−1 with
correlation coefficient >0.9981. The proposed method has been found to have
excellent sensitivity with limit of detection between 0.8 and 13ngL−1
and precision with relative standard deviation values between 4.8 and 9.4% (RSD,
n =5). Good enrichment factors (122–205) and recoveries (85–107%) were obtained
for the extraction of the target analytes in groundwater samples. This simple
and economic method has been successfully applied to analyse real groundwater
samples with satisfactory results.
Graphical abstract
Graphical abstract Highlights
► A
novel method by US-IL-DLLME-LC-FD for fluoroquinolones determination. ► Simple,
rapid and efficient method for water samples. ► Advantages over conventional
methods. ► Low detection limits.
Publication year:
2012 Source:Analytica Chimica Acta, Volume 748 Dayana Rubio Gouvea,
Fernando Meloni, Arthur de Barros Bello Ribeiro, João Luis Callegari Lopes,
Norberto Peporine Lopes Lychnophora salicifolia Mart., which occurs in the
Brazilian Cerrado in the states of Bahia and Minas Gerais as well as in the
southeast of the state of Goiás, is the most widely distributed and also the
most polymorphic species of the genus. This plant is popularly known to have
anti-inflammatory and analgesic activities. In this work, we have studied the
variation in terms of polar metabolites of ninety-three Lychnophora salicifolia
Mart. specimens collected from different regions of the Brazilian Cerrado.
Identification of the constituents of this mixture was carried out by analysis
of the UV spectra and MS data after chromatographic separation. Twenty
substances were identified, including chlorogenic acid derivatives, a flavonoid
C-glucoside, and other sesquiterpenes. The analytical method was validated, and
the reliability and credibility of the results was ensured for the purposes of
this study. The concentration range required for analysis of content variability
within the analyzed group of specimens was covered with appropriate values of
limits of detection and quantitation, as well as satisfactory precision and
recovery. A quantitative variability was observed among specimens collected from
the same location, but on average they were similar from a chemical viewpoint.
In relation to the study involving specimens from different locations, there
were both qualitative and quantitative differences among plants collected from
different regions of Brazil. Statistical analysis revealed that there is a
correlation between geographical localization and polar metabolites profile for
specimens collected from different locations. This is evidence that the pattern
of metabolites concentration depends on the geographical distribution of the
specimens.
Graphical abstract
Graphical abstract Highlights
Statistical analysis revealed
that there is a correlation between geographical localization of Lychnophora
salicifolia samples and polar metabolites profile for specimens collected from
different locations. ► A new HPLC-DAD-MS method for
analysis of the crude extract of L. salicifolia leaves. ► Twenty substances were
identified. ► Ninety-three wild specimens were analyzed. ► A correlation between
geographic isolation and decrease of the chemical similarity. ► The pattern of
metabolites depends on the geographical distribution of the specimens.
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