Biosensors

528 KiB

Open AccessArticle

Development of an Electrochemical-Based Aspartate Aminotransferase Nanoparticle Ir-C Biosensor for Screening of Liver Diseases

by Chang-Jung Hsueh, Joanne H. Wang, Liming Dai and Chung-Chiun Liu

Biosensors 2012, 2(2), 234-244; https://doi.org/10.3390/bios2020234 - 29 May 2012

Cited by 13 | Viewed by 9866

Abstract

Aspartate aminotransaminase (AST) is a hepatocelluar enzyme released into the bloodstream when hepatic cells are damaged, resulting in elevated blood levels of AST. A single use, disposable biosensor prototype, composed of catalytic iridium nano-particles dispersed on carbon paste, was developed to detect enzymatically-produced [...] Read more.

Aspartate aminotransaminase (AST) is a hepatocelluar enzyme released into the bloodstream when hepatic cells are damaged, resulting in elevated blood levels of AST. A single use, disposable biosensor prototype, composed of catalytic iridium nano-particles dispersed on carbon paste, was developed to detect enzymatically-produced H₂O₂ in AST-mediated reactions. This biosensor is capable of measuring AST levels in a phosphate buffer and undiluted human serum over the concentration range of 0 to 0.89 μg/mL AST concentration (corresponding to 0–250 UL⁻¹ specific activity). The biosensor operates at relatively low oxidation potential (+0.3 volt (V) versus the printed Ag/AgCl), minimizing any potential chemical interference in human serum. The measurements of AST in human serum using the biosensor compared well with those measured by standard hospital spectrophotometric assays. This Ir-C biosensor may be useful for AST measurements in the clinical environment. Full article

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463 KiB

Open AccessArticle

Structural Stability and Performance of Noble Metal-Free SnO₂-Based Gas Sensors

by Antonio Tricoli

Biosensors 2012, 2(2), 221-233; https://doi.org/10.3390/bios2020221 - 29 May 2012

Cited by 26 | Viewed by 7363

Abstract

The structural stability of pure SnO₂ nanoparticles and highly sensitive SnO₂-SiO₂ nanocomposites (0–15 SiO₂ wt%) has been investigated for conditions relevant to their utilization as chemoresistive gas sensors. Thermal stabilization by SiO₂ co-synthesis has been investigated at [...] Read more.

The structural stability of pure SnO₂ nanoparticles and highly sensitive SnO₂-SiO₂ nanocomposites (0–15 SiO₂ wt%) has been investigated for conditions relevant to their utilization as chemoresistive gas sensors. Thermal stabilization by SiO₂ co-synthesis has been investigated at up to 600 °C determining regimes of crystal size stability as a function of SiO₂-content. For operation up to 400 °C, thermally stable crystal sizes of ca. 24 and 11 nm were identified for SnO₂ nanoparticles and 1.4 wt% SnO₂-SiO₂ nanocomposites, respectively. The effect of crystal growth during operation (T_O = 320 °C) on the sensor response to ethanol has been reported, revealing possible long-term destabilization mechanisms. In particular, crystal growth and sintering-neck formation were discussed with respect to their potential to change the sensor response and calibration. Furthermore, the effect of SiO₂ cosynthesis on the cross-sensitivity to humidity of these noble metal-free SnO₂-based gas sensors was assessed. Full article

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466 KiB

Open AccessArticle

Detection of Cardiac Biomarkers Using Single Polyaniline Nanowire-Based Conductometric Biosensors

by Innam Lee, Xiliang Luo, Jiyong Huang, Xinyan Tracy Cui and Minhee Yun

Biosensors 2012, 2(2), 205-220; https://doi.org/10.3390/bios2020205 - 14 May 2012

Cited by 102 | Viewed by 14251

Abstract

The detection of myoglobin (Myo), cardiac troponin I (cTnI), creatine kinase-MB (CK-MB), and b-type natriuretic peptide (BNP) plays a vital role in diagnosing cardiovascular diseases. Here we present single site-specific polyaniline (PANI) nanowire biosensors that can detect cardiac biomarkers such as Myo, cTnI, [...] Read more.

The detection of myoglobin (Myo), cardiac troponin I (cTnI), creatine kinase-MB (CK-MB), and b-type natriuretic peptide (BNP) plays a vital role in diagnosing cardiovascular diseases. Here we present single site-specific polyaniline (PANI) nanowire biosensors that can detect cardiac biomarkers such as Myo, cTnI, CK-MB, and BNP with ultra-high sensitivity and good specificity. Using single PANI nanowire-based biosensors integrated with microfluidic channels, very low concentrations of Myo (100 pg/mL), cTnI (250 fg/mL), CK-MB (150 fg/mL), and BNP (50 fg/mL) were detected. The single PANI nanowire-based biosensors displayed linear sensing profiles for concentrations ranging from hundreds (fg/mL) to tens (ng/mL). In addition, devices showed a fast (few minutes) response satisfying respective reference conditions for Myo, cTnI, CK-MB, and BNP diagnosis of heart failure and for determining the stage of the disease. This single PANI nanowire-based biosensor demonstrated superior biosensing reliability with the feasibility of label free detection and improved processing cost efficiency due to good biocompatibility of PANI to monoclonal antibodies (mAbs). Therefore, this development of single PANI nanowire-based biosensors can be applied to other biosensors for cancer or other diseases. Full article

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397 KiB

Open AccessArticle

Peroxide-Dependent Analyte Conversion by the Heme Prosthetic Group, the Heme Peptide “Microperoxidase-11” and Cytochrome c on Chitosan Capped Gold Nanoparticles Modified Electrodes

by Aysu Yarman, Bettina Neumann, Maria Bosserdt, Nenad Gajovic-Eichelmann and Frieder W. Scheller

Biosensors 2012, 2(2), 189-204; https://doi.org/10.3390/bios2020189 - 14 May 2012

Cited by 13 | Viewed by 9546

Abstract

In view of the role ascribed to the peroxidatic activity of degradation products of cytochrome c (cyt c) in the processes of apoptosis, we investigate the catalytic potential of heme and of the cyt c derived heme peptide MP-11 to catalyse the cathodic [...] Read more.

In view of the role ascribed to the peroxidatic activity of degradation products of cytochrome c (cyt c) in the processes of apoptosis, we investigate the catalytic potential of heme and of the cyt c derived heme peptide MP-11 to catalyse the cathodic reduction of hydrogen peroxide and to oxidize aromatic compounds. In order to check whether cyt c has an enzymatic activity in the native state where the protein matrix should suppress the inherent peroxidatic activity of its heme prosthetic group, we applied a biocompatible immobilization matrix and very low concentrations of the co-substrate H₂O₂. The biocatalysts were entrapped on the surface of a glassy carbon electrode in a biocompatible chitosan layer which contained gold nanoparticles. The electrochemical signal for the peroxide reduction is generated by the redox conversion of the heme group, whilst a reaction product of the substrate oxidation is cathodically reduced in the substrate indication. The catalytic efficiency of microperoxidase-11 is sufficient for sensors indicating HRP substrates, e.g., p-aminophenol, paracetamol and catechol, but also the hydroxylation of aniline and dehalogenation of 4-fluoroaniline. The lower limit of detection for p-aminophenol is comparable to previously published papers with different enzyme systems. The peroxidatic activity of cyt c immobilized in the chitosan layer for catechol was found to be below 1 per mill and for p-aminophenol about 3% as compared with that of heme or MP-11. Full article

(This article belongs to the Special Issue Electrochemical Based Biosensors)

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436 KiB

Open AccessArticle

Developing a Real Time Sensing System to Monitor Bacteria in Wound Dressings

by Malcolm J. Farrow, Iain S. Hunter and Patricia Connolly

Biosensors 2012, 2(2), 171-188; https://doi.org/10.3390/bios2020171 - 9 May 2012

Cited by 24 | Viewed by 8509

Abstract

Infection control is a key aspect of wound management strategies. Infection results in chemical imbalances and inflammation in the wound and may lead to prolonged healing times and degradation of the wound surface. Frequent changing of wound dressings may result in damage to [...] Read more.

Infection control is a key aspect of wound management strategies. Infection results in chemical imbalances and inflammation in the wound and may lead to prolonged healing times and degradation of the wound surface. Frequent changing of wound dressings may result in damage to healing tissues and an increased risk of infection. This paper presents the first results from a monitoring system that is being developed to detect presence and growth of bacteria in real time. It is based on impedance sensors that could be placed at the wound-dressing interface and potentially monitor bacterial growth in real time. As wounds can produce large volumes of exudate, the initial system reported here was developed to test for the presence of bacteria in suspension. Impedance was measured using disposable silver-silver chloride electrodes. The bacteria Staphylococcus aureus were chosen for the study as a species commonly isolated from wounds. The growth of bacteria was confirmed by plate counting methods and the impedance data were analysed for discernible differences in the impedance profiles to distinguish the absence and/or presence of bacteria. The main findings were that the impedance profiles obtained by silver-silver chloride sensors in bacterial suspensions could detect the presence of high cell densities. However, the presence of the silver-silver chloride electrodes tended to inhibit the growth of bacteria. These results indicate that there is potential to create a real time infection monitor for wounds based upon impedance sensing. Full article

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3586 KiB

Open AccessReview

Microfabricated Electrochemical Cell-Based Biosensors for Analysis of Living Cells In Vitro

by Jun Wang, Chengxiong Wu, Ning Hu, Jie Zhou, Liping Du and Ping Wang

Biosensors 2012, 2(2), 127-170; https://doi.org/10.3390/bios2020127 - 25 Apr 2012

Cited by 54 | Viewed by 19841

Abstract

Cellular biochemical parameters can be used to reveal the physiological and functional information of various cells. Due to demonstrated high accuracy and non-invasiveness, electrochemical detection methods have been used for cell-based investigation. When combined with improved biosensor design and advanced measurement systems, the [...] Read more.

Cellular biochemical parameters can be used to reveal the physiological and functional information of various cells. Due to demonstrated high accuracy and non-invasiveness, electrochemical detection methods have been used for cell-based investigation. When combined with improved biosensor design and advanced measurement systems, the on-line biochemical analysis of living cells in vitro has been applied for biological mechanism study, drug screening and even environmental monitoring. In recent decades, new types of miniaturized electrochemical biosensor are emerging with the development of microfabrication technology. This review aims to give an overview of the microfabricated electrochemical cell-based biosensors, such as microelectrode arrays (MEA), the electric cell-substrate impedance sensing (ECIS) technique, and the light addressable potentiometric sensor (LAPS). The details in their working principles, measurement systems, and applications in cell monitoring are covered. Driven by the need for high throughput and multi-parameter detection proposed by biomedicine, the development trends of electrochemical cell-based biosensors are also introduced, including newly developed integrated biosensors, and the application of nanotechnology and microfluidic technology. Full article

(This article belongs to the Special Issue Electrochemical Based Biosensors)

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Graphical abstract

573 KiB

Open AccessArticle

Optical Gratings Coated with Thin Si₃N₄ Layer for Efficient Immunosensing by Optical Waveguide Lightmode Spectroscopy

by Lorena Diéguez, David Caballero, Josep Calderer, Mauricio Moreno, Elena Martínez and Josep Samitier

Biosensors 2012, 2(2), 114-126; https://doi.org/10.3390/bios2020114 - 10 Apr 2012

Cited by 26 | Viewed by 16490

Abstract

New silicon nitride coated optical gratings were tested by means of Optical Waveguide Lightmode Spectroscopy (OWLS). A thin layer of 10 nm of transparent silicon nitride was deposited on commercial optical gratings by means of sputtering. The quality of the layer was tested [...] Read more.

New silicon nitride coated optical gratings were tested by means of Optical Waveguide Lightmode Spectroscopy (OWLS). A thin layer of 10 nm of transparent silicon nitride was deposited on commercial optical gratings by means of sputtering. The quality of the layer was tested by x-ray photoelectron spectroscopy and atomic force microscopy. As a proof of concept, the sensors were successfully tested with OWLS by monitoring the concentration dependence on the detection of an antibody-protein pair. The potential of the Si₃N₄ as functional layer in a real-time biosensor opens new ways for the integration of optical waveguides with microelectronics. Full article

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Biosensors, Volume 2, Issue 2 (June 2012) – 7 articles , Pages 114-244

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