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World Congress on Biosensors 2014
Biosensors 2014
Tuesday 11 September 2012
Just Published: Biosensors & Bioelectronics
A new issue of this journal has just
been published. To see abstracts of the papers it contains (with links through
to the full papers) click here:
Publication year: 2013 Source:Biosensors and Bioelectronics, Volume 39, Issue 1 Vivek P. Raje, Patrícia I. Morgado, Maximiano P. Ribeiro, Ilídio J. Correia, Vasco D.B. Bonifácio, Paula S. Branco, Ana Aguiar-Ricardo A water-soluble biocompatible aziridine-based biosensor with pendant anthracene units was synthesized by radicalar polymerization of N-substituted aziridines in supercritical carbon dioxide. The binding ability of the sensor towards a series of metal ions was examined by comparing the fluorescence intensities of the solutions before and after the addition of 100 equivalents of a solution of the metal ion chloride salt. A fast, simple and highly optical sensitive dual behavior, “off–on” and “on–off” response, was observed after the biosensor was exposed to the metal cations in aqueous solution. Zinc presented the highest fluorescence enhancement (turn-on) and copper presented the highest fluorescence quenching (turn-off). The response time was found to be instantaneous and the detection limit was achieved even in the presence of excess metal cation competitors. By using immunofluorescence microscopy it was also shown that oligoaziridine acts as an “on–off” probe through highly sensitive (detection limit of 1.6nM), selective and reversible binding to copper anions under physiologic conditions using living Human Fibroblast cells. The stoichiometry for the reaction of the biosensor with Cu2+ was determined by a Job plot and indicates the formation of an oligoaziridine-Cu2+ 1:2 adduct.
Graphical abstract
Graphical Abstract Highlights
► A water-soluble biocompatible aziridine-based biosensor was synthesized in scCO2. ► The biosensor presents a dual behavior when exposed to different metal cations. ► Zinc displays the highest fluorescence enhancement (turn-on). ► Cu2+ shows the highest fluorescence quenching (turn-off) with detection limit of 1.6nM. ► The biosensor is able to detect traces of Cu2+ within living Human Fibroblast cells.
Publication year:
2013 Source:Biosensors and Bioelectronics, Volume 39, Issue
1 Elizabeth Schneider, Douglas S. Clark Cytochrome P450s (CYPs) are a
large family of heme-containing monooxygenase enzymes involved in the first-pass
metabolism of drugs and foreign chemicals in the body. CYP reactions, therefore,
are of high interest to the pharmaceutical industry, where lead compounds in
drug development are screened for CYP activity. CYP reactions in vivo require
the cofactor NADPH as the source of electrons and an additional enzyme,
cytochrome P450 reductase (CPR), as the electron transfer partner; consequently,
any laboratory or industrial use of CYPs is limited by the need to supply NADPH
and CPR. However, immobilizing CYPs on an electrode can eliminate the need for
NADPH and CPR provided the enzyme can accept electrons directly from the
electrode. The immobilized CYP can then act as a biosensor for the detection of
CYP activity with potential substrates, albeit only if the immobilized enzyme is
electroactive. The quest to create electroactive CYPs has led to many different
immobilization strategies encompassing different electrode materials and surface
modifications. This review focuses on different immobilization strategies that
have been used to create CYP biosensors, with particular emphasis on mammalian
drug-metabolizing CYPs and characterization of CYP electrodes. Traditional
immobilization methods such as adsorption to thin films or encapsulation in
polymers and gels remain robust strategies for creating CYP biosensors; however,
the incorporation of novel materials such as gold nanoparticles or quantum dots
and the use of microfabrication are proving advantageous for the creation of
highly sensitive and portable CYP biosensors.
Highlights
► An overview of the significance of CYP enzymes
and CYP biosensors. ► A brief history of the development of CYP biosensors. ► A
review of electrode types and modifications used to create CYP biosensors. ►
Highlights of recent and/or novel studies on CYP biosensors. ► Focus on chemical
and physical characterization of CYP electrodes.
Publication year:
2013 Source:Biosensors and Bioelectronics, Volume 39, Issue 1 C.F.
Soon, M. Youseffi, R.F. Berends, N. Blagden, M.C.T. Denyer Keratinocyte
traction forces play a crucial role in wound healing. The aim of this study was
to develop a novel cell traction force (CTF) transducer system based on
cholesteryl ester liquid crystals (LC). Keratinocytes cultured on LC induced
linear and isolated deformation lines in the LC surface. As suggested by the
fluorescence staining, the deformation lines appeared to correlate with the
forces generated by the contraction of circumferential actin filaments which
were transmitted to the LC surface via the focal adhesions. Due to the linear
viscoelastic behavior of the LC, Hooke's equation was used to quantify the CTFs
by associating Young's modulus of LC to the cell induced stresses and biaxial
strain in forming the LC deformation. Young's modulus of the LC was profiled by
using spherical indentation and determined at approximately 87.1±17.2kPa. A new
technique involving cytochalasin-B treatment was used to disrupt the
intracellular force generating actin fibers, and consequently the biaxial strain
in the LC induced by the cells was determined. Due to the improved sensitivity
and spatial resolution (∼1μm) of the LC based CTF transducer, a wide range of
CTFs was determined (10–120nN). These were found to be linearly proportional to
the length of the deformations. The linear relationship of CTF-deformations was
then applied in a bespoke CTF mapping software to estimate CTFs and to map CTF
fields. The generated CTF map highlighted distinct distributions and different
magnitude of CTFs were revealed for polarized and non-polarized keratinocytes.
Highlights
► Novel LC based cell traction force transducer has
been developed. ► Transducer is highly sensitive to localized cell traction
forces (CTFs). ► CTFs for polarized and non-polarized cells are estimated via
the sensing system. ► It has potential to be a cell-based pharmacological
assay.
Publication year:
2013 Source:Biosensors and Bioelectronics, Volume 39, Issue
1 Mengyun Xu, Xiliang Luo, Jason J. Davis Insulin, a polypeptide hormone
secreted by pancreatic cells, is a key regulator in glucose homeostasis. Its
deficiency leads to insulin-dependent (type I) diabetes whereas resistance to
insulin is common in type II diabetes, obesity and a range of endocrine
disorders. Its determination is of considerable value, particularly in the
clinical diagnosis of diabetes mellitus and the doping control of athletes. It
has, additionally, been noted as a potential breast cancer marker (serum insulin
levels being found to be raised in comparison to control patients).
Electrochemical assays are potentially very cheap, highly sensitive, and very
readily transposed to a point of care. Though there exist numerous examples of
label free impedimetric or capacitative assaying of biomolecules, these are
rarely demonstrated to be effective in complex biological mixtures or to be
applicable to low molecular weight targets (since they operate through the
interfacial displacement of water/ions and/or the steric blocking of a redox
probe). We report herein an ultrasensitive electrochemical and label-free
biosensor for insulin in blood serum with a clinically relevant linear range and
detection limit of 1.2pM. The transducing surfaces, based on readily prepared,
antibody modified, polyethylene glycol monolayer modified polycrystalline gold
surfaces, respond in a highly specific and re-useable manner to the target in up
to 50% blood serum.
Highlights
► The low molecular weight, clinically important
polypeptide, insulin, can be reliably and selectively assayed in blood by a
label free facile impedance immunoassay. ► Assays span entire clinically
relevant range with low pM limits of detection. ► There is no precedent for the
label free impedance assaying this protein and very little precedent for the
label free detection of targets of this molecular weight in complex media. ► The
receptive surfaces are readily generated and reuseable.
Publication year:
2013 Source:Biosensors and Bioelectronics, Volume 39, Issue
1 Zhanlong Mei, Huaqin Chu, Wei Chen, Feng Xue, Jian Liu, Huaneng Xu, Rui
Zhang, Lei Zheng A simple, one-step, rapid method to detect bisphenol A (BPA)
using a label-free aptasensor is presented. A high selective anti-BPA aptamer
was added to gold nanoparticles (GNPs) to prepare the label-free aptasensor for
BPA, which maintains good tolerance of GNPs under aqueous conditions with high
salt concentrations. With the presence of BPA in the aptasensor system, the GNPs
would aggregate by competitive binding of BPA and aptamer. Detection results can
be visualized by the aggregation-induced color change of GNPs without the use of
any instrumentation. The limit of visual detection (LOD) was found to be
0.1ng/mL by naked-eye observation, which was competitive to some current rapid
BPA detection methods, even some instrumental based methods. Besides the obvious
advantages, including reduced detection time and operation procedures, the
results of this method meet the various detection requirements for BPA and are
comparable to the traditional ELISA and instrument-based methods. The proposed
one-step, label-free method was successfully used to determine BPA in actual
water samples.
Highlights
► On-site BPA detection using one step, label-free
aptasensor. ► BPA detection with sensitivity of 0.1ng/mL by naked-eye, which is
comparable to current methods. ► Successful application of the developed method
in actual water samples. ► Providing a potential tool for water quality control
and early diagnostic of BPA related disease.
Publication year:
2013 Source:Biosensors and Bioelectronics, Volume 39, Issue 1 Reza
Karimi Shervedani, Zakyeh Akrami Deferrioxamine, a bacterial hydroxamic
siderophore having high binding affinity for Fe(III), is used in its immobilized
form, as self-assembled monolayer on Au, for accumulation and recognition of
Fe(III) from the solution phase. The accumulated Fe(III) is detected via both
active mode based on faradaic reduction current of Fe(III), and inactive mode
based on impedimetric effect of accumulated Fe(III) against redox reaction of a
suitable probe. Appropriate electrochemical techniques, square wave voltammetry
and electrochemical impedance spectroscopy, are used for the transduction of
analytical signals obtained by this sensor. Then, the parameters influencing the
sensor response are optimized. In the best conditions, a linear response, from
1.0×10−10 to 1.0×10−7 M Fe(III) in logarithmic scale with
a detection limit of 2.0×10−11 M, and mean relative standard
deviation of 1.7% for n=4 is observed. The results show that the sensor can be
used for determination of Fe(III) in the presence of various inorganic ions and
biological species. Validity of the method and applicability of the sensor are
successfully tested by determination of Fe(III) in various real samples
including plant tissue (corn leaves), industrial alloy (Ferrotitanium), and
pharmaceutical samples (Venofer® ampoule, Ironorm®
capsule, and V.M. Protein® powder).
Highlights
► A new biosensor using Deferrioxamine, a bacterial
siderophore, fixed on Au is explained for Fe(III). ► The sensor is characterized
by voltammetry and electrochemical impedance spectroscopy. ► Merits of the
method include easy fabrication, wide response range, high selectivity and
stability. ► The sensor is successfully tested for Fe(III) in pharmaceutical,
industrial, and plant samples.
Publication year:
2013 Source:Biosensors and Bioelectronics, Volume 39, Issue
1 Céline A. Mandon, Ophélie I. Berthuy, Benjamin P. Corgier, Gaelle C. Le
Goff, Patrice Faure, Patrice N. Marche, Loïc J. Blum, Christophe A.
Marquette The present report describes the integration and application
possibilities of a new microarray concept based on adhesive surface. The method
was shown to enable the straightforward production of 384 and 1536-well plates
modified with 100 and 25 spots per well, respectively. Such in-well densities
were only possible thanks to the fabrication process which implies first the
deposition of the microarray on a flat adhesive surface and then its assembly
with bottomless 384 or 1536-well plates. The concept was also confronted to
various applications such as oligonucleotide detection, localised cell culture
onto spotted adhesion proteins and immobilisation of peptide or active
antibodies for immunoassays. In the particular case of immunotesting, the study
focused on liver diseases diagnosis and more particularly on the detection of
either one liver cancer marker, the alpha-fetoprotein, or the detection of
Hepatitis C Virus infection. In every cases, interesting performances were
obtained directly in crude patient serum, proof of the robust and generic aspect
of the platform.
Highlights
► Adhesive microarrays shall be the cost-efficient
approach for high-throughput analysis tools. ► Tests were carried out in 96, 384
and 1536-well assemblies suitable for automated analysis. ► We present
analytical results of DNA, antibodies and proteins detection, directly in sera.
► The adhesive microarray support is also suitable for localized cell
culture.
Publication year:
2013 Source:Biosensors and Bioelectronics, Volume 39, Issue
1 Gyeong Sook Bang, Suhyung Cho, Nahum Lee, Bo-Rahm Lee, June-Hyung Kim,
Byung-Gee Kim An aptamer can be redesigned to new functional molecules by
conjugating with other oligonucleotides. However, it requires experimental
trials to optimize the conjugating module with the sensitivity and selectivity
toward a target. To reduce these efforts, we report rationally-designed modular
allosteric aptamer sensor (MAAS), which is composed of coupled two aptamers and
the regulator. For label-free protein detection, the protein–aptamer was
conjugated with the malachite green (MG) aptamer for signaling. The MAAS
additionally has the regulator domain which is designed to hybridize to a
protein binding domain. The regulator makes MAAS to be inactive by destructing
the original structure of the two aptamers. However, its conformation becomes
active by dissociating the hybridization from the protein recognition signal,
thereby inducing the binding of MG emitting the enhanced fluorescence. The
design of regulator is based on the thermodynamic energy difference by the RNA
conformational change and protein–aptamer affinity. Here we first demonstrated
the MAAS for hepatitis C helicase and replicase. The target proteins were
detected up to 250nM with minimized blank signals and displayed high
specificities 10-fold greater than in non-specific proteins. The MAAS provides
valuable tools that can be adapted to a wide range of configurations in
bioanalytical applications.
Highlights
► We established modular allosteric aptamer sensor
(MAAS) for label-free detection. ► The MAAS was engineered by aptamers for
protein–dye and the antisense regulator. ► Rational-designed MAASs sensitively
detected HCV proteins up to 250nM. ► The MAAS showed the high specificity to
target protein from other proteins over 10-fold. ► The MAAS was functional both
in homogeneous and heterogeneous format.
Publication year:
2013 Source:Biosensors and Bioelectronics, Volume 39, Issue
1 Chunhua Feng, Xianjun Yue, Fangbai Li, Chaohai Wei Microbial reduction
of insoluble iron minerals by dissimilatory iron reducing bacteria (DIRB) is an
important environment process in the iron biogeochemical cycle. We reported that
the bio-current generated from oxidation of organic matter by these bacteria in
the presence of iron oxides can be used as an indicator for microbial
dissolution of insoluble iron oxides. Bioelectrochemical experiments were
conducted to investigate the effects of the specific bacteria and the phase
identity of iron oxides on bio-current generation by recording the current
response as a result of a poised constant potential. Experimental results
indicated that the bio-current generation can be greatly enhanced by iron oxide
addition under all the conditions varying in the type of pure culture or iron
oxide. The increase in the bio-current was linearly correlated with the
increased concentration of biogenic Fe(II) detected either by chemical analysis
or cyclic voltammetry (CV) tests. This can be understood based on the proposed
mechanism that the Fe(II)/Fe(III) couple functions as the electron mediator
shuttling electrons from the microbes to the electrodes.
Highlights
► Iron oxide addition significantly enhanced
bio-current generation by electrochemically active bacteria. ► The increase in
the bio-current was linearly correlated with the increased concentration of
biogenic Fe(II). ► The Fe(II)/Fe(III) couple-mediated electron transfer from the
microbes to the electrodes was proposed.
Publication year:
2013 Source:Biosensors and Bioelectronics, Volume 39, Issue 1 Judy
Gopal, Nazim Hasan, Hui-Fen Wu For the first time, we report the fabrication
of a titanium bacterial chip for MALDI-MS produced from a simple, cost effective
and rapid heat treatment process. This bacterial chip can be reused many times
and is highly versatile. These bacterial chips serve dual roles: (1) They can be
applied as MALDI-MS target plates for direct and highly sensitive bacterial
analysis. (2) They can be used as bacterial sensors for direct analysis of the
captured bacteria using MALDI-MS. The sensitivity of these chips when used as
bacterial sensors is <103 cfu/mL. The lowest detectable
concentration for direct MALDI-MS analysis was found to be 104
cfu/mL. The results were further justified by using standard plate counting
method combined with Tukey–Kramer statistical analysis and fluorescence imaging
followed by image processing for fluorescence quantification using ImageJ
software to substantiate the MALDI-MS results.
Highlights
► For first time report fabrication of titanium
biochip for MALDI-MS. ► Produced from simple, cost effective rapid heat
treatment process. ► Biochips serve dual purposes. MALDI-MS target plates for
direct bacteria analysis. ► Biosensors for direct analysis of the captured
bacteria using MALDI-MS. ► Sensitivity of these chips as biosensors is
<103 cfu/mL.
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