World Congress on Biosensors 2014

World Congress on Biosensors 2014
Biosensors 2014

Tuesday, 24 September 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:

Preparation and characterization of three dimensional graphene foam supported platinum–ruthenium bimetallic nanocatalysts for hydrogen peroxide based electrochemical biosensors

24 September 2013, 00:50:18
Publication date: 15 February 2014
Source:Biosensors and Bioelectronics, Volume 52
Author(s): Chih-Chien Kung , Po-Yuan Lin , Frederick John Buse , Yuhua Xue , Xiong Yu , Liming Dai , Chung-Chiun Liu
The large surface, the excellent dispersion and the high degrees of sensitivity of bimetallic nanocatalysts were the attractive features of this investigation. Graphene foam (GF) was a three dimensional (3D) porous architecture consisting of extremely large surface and high conductive pathways. In this study, 3D GF was used incorporating platinum–ruthenium (PtRu) bimetallic nanoparticles as an electrochemical nanocatalyst for the detection of hydrogen peroxide (H2O2). PtRu/3D GF nanocatalyst exhibited a remarkable performance toward electrochemical oxidation of H2O2 without any additional mediator showing a high sensitivity (1023.1µAmM−1 cm−2) and a low detection limit (0.04µM) for H2O2. Amperometric results demonstrated that GF provided a promising platform for the development of electrochemical sensors in biosensing and PtRu/3D GF nanocatalyst possessed the excellent catalytic activity toward the H2O2 detection. A small particle size and a high degree of the dispersion in obtaining of large active surface area were important for the nanocatalyst for the best H2O2 detection in biosensing. Moreover, potential interference by ascorbic acid and uric acid appeared to be negligible.

Novel paper-based cholesterol biosensor using graphene/polyvinylpyrrolidone/polyaniline nanocomposite

24 September 2013, 00:50:18
Publication date: 15 February 2014
Source:Biosensors and Bioelectronics, Volume 52
Author(s): Nipapan Ruecha , Ratthapol Rangkupan , Nadnudda Rodthongkum , Orawon Chailapakul
A novel nanocomposite of graphene (G), polyvinylpyrrolidone (PVP) and polyaniline (PANI) has been successfully prepared and used for the modification of paper-based biosensors via electrospraying. The droplet-like nanostructures of G/PVP/PANI-modified electrodes are obtained with an average size of 160±1.02nm. Interestingly, the presence of small amount of PVP (2mgmL−1) in the nanocomposites can substantially improve the dispersibility of G and increase the electrochemical conductivity of electrodes, leading to enhanced sensitivity of the biosensor. The well-defined cyclic voltammogram of standard ferri/ferrocyanide is achieved on a G/PVP/PANI-modified electrode with a 3-fold increase in the current signal compared to an unmodified electrode. This modified electrode also exhibits excellent electrocatalytic activity towards the oxidation of hydrogen peroxide (H2O2). Furthermore, cholesterol oxidase (ChOx) is attached to G/PVP/PANI-modified electrode for the amperometric determination of cholesterol. Under optimum conditions, a linear range of 50μM to 10mM is achieved and the limit of detection is found to be 1 μM for cholesterol. Finally, the proposed system can be applied for the determination of cholesterol in a complex biological fluid (i.e. human serum).

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A highly sensitive prostate-specific antigen immunosensor based on gold nanoparticles/PAMAM dendrimer loaded on MWCNTS/chitosan/ionic liquid nanocomposite

24 September 2013, 00:50:18
Publication date: 15 February 2014
Source:Biosensors and Bioelectronics, Volume 52
Author(s): Begard Kavosi , Abdollah Salimi , Rahman Hallaj , Kamal Amani
We have developed a sensitive electrochemical immunosensor for the detection of prostate-specific antigen (PSA), based on covalently immobilizing of anti-PSA and redox mediator (thionine) onto gold nanoparticles–incorporated polyamidoamine dendrimer (AuNPs–PAMAM) and multiwalled carbon nanotubes/ionic liquid/chitosan nanocomposite (MWCNTs/IL/Chit) as the support platform. The MWCNTs/IL/Chit nanocomposite and synthesized AuNPs were characterized using SEM and TEM microscopy techniques. Greatly amplified immunoassay was established by sandwiching the antigen between anti-PSA immobilized on the MWCNTs/IL/Chit/AuNPs–PAMAM interface and anti-PSA labeled with horseradish peroxidase (HRP-labeled anti-PSA) as secondary antibody. Phtaloyl chloride (Ph) was used as linking agent for the subsequent immobilization of AuNPs–PAMAM onto platform and anti-PSA antibody and thionine onto AuNPs–PAMAM dendrimer. The increased electrocatalytic reduction of H2O2 by HRP was monitored by differential pulse voltammetry technique. Under optimized condition the calibration curve for PSA concentration was linear up to 80ngml−1 with detection limit (signal-to-noise ratio of 3) of 1pgml−1. AuNPs–PAMAM dendrimer as platform not only increased the amount of thionine and PSA antibody but also the electron transfer process accelerated by encapsulated AuNPs. Moreover, the proposed PSA immunosensor exhibited excellent stability and reproducibility. Accurate detection of PSA in human serum samples was demonstrated by comparison to standard ELISA assays. In addition, impedance technique was used as simple, rapid, low cost label free analytical method for PSA measurement with detection limit of 0.5ngml−1 at concentration range up to 25ngml−1. The results indicate that the present protocol is quite promising in developing other electrochemical immunosensors.

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“Turn off–on” fluorescent sensor for platinum drugs-DNA interactions based on quantum dots

24 September 2013, 00:50:18
Publication date: 15 February 2014
Source:Biosensors and Bioelectronics, Volume 52
Author(s): Dan Zhao , Jiaotian Li , Tianming Yang , Zhike He
A “turn off–on” mode has been established by using the interaction between platinum anticancer drugs and DNA as input signal and the fluorescence reversible change of quantum dots (QDs) as output signal. The QDs fluorescence can be quenched by platinum anticancer drugs via photo-induced electron transfer process, rendering the system into “turn off” status, and the system can then be “turned on” when fluorescence is restored due to covalent conjugation between DNA and platinum anticancer drugs. This dual-directional fluorescence change realized the detection of cisplatin and DNA, overcoming the selectivity problem commonly existed in the traditional mono-directional fluorescence detection mode. The reversible fluorescent “turn off-on” mode has been further employed to study the interactions between DNA and different platinum anticancer drugs (cisplatin, oxaliplatin and carboplatin). Furthermore, the impacts of different types of DNAs (different in base sequence, chain length and ssDNA/dsDNA) on the mode are also explored. This simple, fast and convenient spectroscopic method owns promising applications in the study on interaction between medical molecules and DNA, and in biochemical detections.

Analysis of cell surface antigens by Surface Plasmon Resonance imaging

24 September 2013, 00:50:18
Publication date: 15 February 2014
Source:Biosensors and Bioelectronics, Volume 52
Author(s): Ivan Stojanović , Richard B.M. Schasfoort , Leon W.M.M. Terstappen
Surface Plasmon Resonance (SPR) is most commonly used to measure bio-molecular interactions. SPR is used significantly less frequent for measuring whole cell interactions. Here we introduce a method to measure whole cells label free using the specific binding of cell surface antigens expressed on the surface of cancer cells and specific ligands deposited on sensor chips using an IBIS MX96 SPR imager (SPRi). As a model system, cells from the breast cancer cell line HS578T, SKBR3 and MCF7 were used. SPRi responses to Epithelial Cell Adhesion Molecule (EpCAM) antibody and other ligands coated on the sensor chips were measured. SPR curves show a response attributable to the sedimentation of the cells and a specific binding response on top of the initial response, the magnitude of which is dependent on the ligand density and the cell type used. Comparison of SPRi with flow cytometry showed similar EpCAM expression on MCF7, SKBR3 and HS578T cells.

Graphene oxide as nanogold carrier for ultrasensitive electrochemical immunoassay of Shewanella oneidensis with silver enhancement strategy

24 September 2013, 00:50:18
Publication date: 15 February 2014
Source:Biosensors and Bioelectronics, Volume 52
Author(s): Junlin Wen , Shungui Zhou , Yong Yuan
The genus Shewanella is ubiquitous in environment and has been extensively studied for their applications in bioremediation. A novel immunoassay for ultrasensitive detection of Shewanella oneidensis was presented based on graphene oxide (GO) as nanogold carrier with silver enhancement strategy. The enhanced sensitivity was achieved by employing conjugate-featuring gold nanoparticles (AuNPs) and antibodies (Ab) assembled on bovine serum albumin (BSA)-modified GO (Ab/AuNPs/BSA/GO). After a sandwich-type antigen–antibody reaction, Ab/AuNPs/BSA/GO conjugate binding on the target analyte produced an enhanced immune-recognition response by the reduction of silver ion in the present of hydroquinone. The deposited silver metal was dissolved with nitric acid and subsequently quantified by anodic stripping voltammetry. The high AuNPs loading capacity of GO and the obvious signal amplification by gold-catalyzed silver deposition offer an excellent detection method with a wide range of linear relationship between 7.0×101 and 7.0×107 cfu/mL. Furthermore, the immunoassay developed in this work exhibited high sensitivity, acceptable stability and reproducibility. This simple and sensitive assay method has promising application in various fields for rapid detection of bacteria, protein and DNA. 

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