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Biosensors
Volume 6
Issue 2
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Biosensors, Volume 6, Issue 2 (June 2016) – 17 articles

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2994 KiB  
Article
Computational Assessment of Neural Probe and Brain Tissue Interface under Transient Motion
by Michael Polanco, Sebastian Bawab and Hargsoon Yoon
Biosensors 2016, 6(2), 27; https://doi.org/10.3390/bios6020027 - 16 Jun 2016
Cited by 28 | Viewed by 6316
Abstract
The functional longevity of a neural probe is dependent upon its ability to minimize injury risk during the insertion and recording period in vivo, which could be related to motion-related strain between the probe and surrounding tissue. A series of finite element [...] Read more.
The functional longevity of a neural probe is dependent upon its ability to minimize injury risk during the insertion and recording period in vivo, which could be related to motion-related strain between the probe and surrounding tissue. A series of finite element analyses was conducted to study the extent of the strain induced within the brain in an area around a neural probe. This study focuses on the transient behavior of neural probe and brain tissue interface with a viscoelastic model. Different stages of the interface from initial insertion of neural probe to full bonding of the probe by astro-glial sheath formation are simulated utilizing analytical tools to investigate the effects of relative motion between the neural probe and the brain while friction coefficients and kinematic frequencies are varied. The analyses can provide an in-depth look at the quantitative benefits behind using soft materials for neural probes. Full article
(This article belongs to the Special Issue Neural Sensing and Interfacing Technology)
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4551 KiB  
Article
Integrating Nanostructured Artificial Receptors with Whispering Gallery Mode Optical Microresonators via Inorganic Molecular Imprinting Techniques
by G. Denise Hammond, Adam L. Vojta, Sheila A. Grant and Heather K. Hunt
Biosensors 2016, 6(2), 26; https://doi.org/10.3390/bios6020026 - 15 Jun 2016
Cited by 6 | Viewed by 8543
Abstract
The creation of label-free biosensors capable of accurately detecting trace contaminants, particularly small organic molecules, is of significant interest for applications in environmental monitoring. This is achieved by pairing a high-sensitivity signal transducer with a biorecognition element that imparts selectivity towards the compound [...] Read more.
The creation of label-free biosensors capable of accurately detecting trace contaminants, particularly small organic molecules, is of significant interest for applications in environmental monitoring. This is achieved by pairing a high-sensitivity signal transducer with a biorecognition element that imparts selectivity towards the compound of interest. However, many environmental pollutants do not have corresponding biorecognition elements. Fortunately, biomimetic chemistries, such as molecular imprinting, allow for the design of artificial receptors with very high selectivity for the target. Here, we perform a proof-of-concept study to show how artificial receptors may be created from inorganic silanes using the molecular imprinting technique and paired with high-sensitivity transducers without loss of device performance. Silica microsphere Whispering Gallery Mode optical microresonators are coated with a silica thin film templated by a small fluorescent dye, fluorescein isothiocyanate, which serves as our model target. Oxygen plasma degradation and solvent extraction of the template are compared. Extracted optical devices are interacted with the template molecule to confirm successful sorption of the template. Surface characterization is accomplished via fluorescence and optical microscopy, ellipsometry, optical profilometry, and contact angle measurements. The quality factors of the devices are measured to evaluate the impact of the coating on device sensitivity. The resulting devices show uniform surface coating with no microstructural damage with Q factors above 106. This is the first report demonstrating the integration of these devices with molecular imprinting techniques, and could lead to new routes to biosensor creation for environmental monitoring. Full article
(This article belongs to the Special Issue Nanostructured Thin Films for Optical Biosensing)
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6904 KiB  
Article
Optimal Magnetic Field for Crossing Super-Para-Magnetic Nanoparticles through the Brain Blood Barrier: A Computational Approach
by Maysam Z. Pedram, Amir Shamloo, Aria Alasty and Ebrahim Ghafar-Zadeh
Biosensors 2016, 6(2), 25; https://doi.org/10.3390/bios6020025 - 14 Jun 2016
Cited by 44 | Viewed by 8091
Abstract
This paper scrutinizes the magnetic field effect to deliver the superparamagnetic nanoparticles (SPMNs) through the Blood Brain Barrier (BBB). Herein we study the interaction between the nanoparticle (NP) and BBB membrane using Molecular Dynamic (MD) techniques. The MD model is used to enhance [...] Read more.
This paper scrutinizes the magnetic field effect to deliver the superparamagnetic nanoparticles (SPMNs) through the Blood Brain Barrier (BBB). Herein we study the interaction between the nanoparticle (NP) and BBB membrane using Molecular Dynamic (MD) techniques. The MD model is used to enhance our understanding of the dynamic behavior of SPMNs crossing the endothelial cells in the presence of a gradient magnetic field. Actuation of NPs under weak magnetic field offers the great advantage of a non-invasive drug delivery without the risk of causing injury to the brain. Furthermore, a weak magnetic portable stimulator can be developed using low complexity prototyping techniques. Based on MD simulation results in this paper, SPMNs can cross the cell membrane while experiencing very weak mechanical forces in the range of pN. This study also derives guidelines for the design of the SPMNs dedicated to crossing the BBB using external magnetic fields. Full article
(This article belongs to the Special Issue Micro- and Nano-Bio-Interfaces)
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Article
Rapid Detection of Food Allergens by Microfluidics ELISA-Based Optical Sensor
by Xuan Weng, Gautam Gaur and Suresh Neethirajan
Biosensors 2016, 6(2), 24; https://doi.org/10.3390/bios6020024 - 7 Jun 2016
Cited by 89 | Viewed by 18348
Abstract
The risks associated with the presence of hidden allergens in food have increased the need for rapid, sensitive, and reliable methods for tracing food allergens in commodities. Conventional enzyme immunosorbent assay (ELISA) has usually been performed in a centralized lab, requiring considerable time [...] Read more.
The risks associated with the presence of hidden allergens in food have increased the need for rapid, sensitive, and reliable methods for tracing food allergens in commodities. Conventional enzyme immunosorbent assay (ELISA) has usually been performed in a centralized lab, requiring considerable time and sample/reagent consumption and expensive detection instruments. In this study, a microfluidic ELISA platform combined with a custom-designed optical sensor was developed for the quantitative analysis of the proteins wheat gluten and Ara h 1. The developed microfluidic ELISA biosensor reduced the total assay time from hours (up to 3.5 h) to 15–20 min and decreased sample/reagent consumption to 5–10 μL, compared to a few hundred microliters in commercial ELISA kits, with superior sensitivity. The quantitative capability of the presented biosensor is a distinctive advantage over the commercially available rapid methods such as lateral flow devices (LFD) and dipstick tests. The developed microfluidic biosensor demonstrates the potential for sensitive and less-expensive on-site determination for rapidly detecting food allergens in a complex sample system. Full article
(This article belongs to the Special Issue Novel Nanobiosensors for Environmental, Food and Clinical Analyses)
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3174 KiB  
Article
Broadband 120 MHz Impedance Quartz Crystal Microbalance (QCM) with Calibrated Resistance and Quantitative Dissipation for Biosensing Measurements at Higher Harmonic Frequencies
by Manuel Kasper, Lukas Traxler, Jasmina Salopek, Herwig Grabmayr, Andreas Ebner and Ferry Kienberger
Biosensors 2016, 6(2), 23; https://doi.org/10.3390/bios6020023 - 25 May 2016
Cited by 19 | Viewed by 9378
Abstract
We developed an impedance quartz crystal microbalance (QCM) approach with the ability to simultaneously record mass changes and calibrated energy dissipation with high sensitivity using an impedance analyzer. This impedance QCM measures frequency shifts and resistance changes of sensing quartz crystals very stable, [...] Read more.
We developed an impedance quartz crystal microbalance (QCM) approach with the ability to simultaneously record mass changes and calibrated energy dissipation with high sensitivity using an impedance analyzer. This impedance QCM measures frequency shifts and resistance changes of sensing quartz crystals very stable, accurately, and calibrated, thus yielding quantitative information on mass changes and dissipation. Resistance changes below 0.3 Ω were measured with corresponding dissipation values of 0.01 µU (micro dissipation units). The broadband impedance capabilities allow measurements between 20 Hz and 120 MHz including higher harmonic modes of up to 11th order for a 10 MHz fundamental resonance frequency quartz crystal. We demonstrate the adsorbed mass, calibrated resistance, and quantitative dissipation measurements on two biological systems including the high affinity based avidin-biotin interaction and nano-assemblies of polyelectrolyte layers. The binding affinity of a protein-antibody interaction was determined. The impedance QCM is a versatile and simple method for accurate and calibrated resistance and dissipation measurements with broadband measurement capabilities for higher harmonics measurements. Full article
(This article belongs to the Special Issue Raman and IR Spectroscopic Sensing)
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2784 KiB  
Article
A Flow SPR Immunosensor Based on a Sandwich Direct Method
by Mauro Tomassetti, Giorgia Conta, Luigi Campanella, Gabriele Favero, Gabriella Sanzò, Franco Mazzei and Riccarda Antiochia
Biosensors 2016, 6(2), 22; https://doi.org/10.3390/bios6020022 - 13 May 2016
Cited by 19 | Viewed by 7003
Abstract
In this study, we report the development of an SPR (Surface Plasmon Resonance) immunosensor for the detection of ampicillin, operating under flow conditions. SPR sensors based on both direct (with the immobilization of the antibody) and competitive (with the immobilization of the antigen) [...] Read more.
In this study, we report the development of an SPR (Surface Plasmon Resonance) immunosensor for the detection of ampicillin, operating under flow conditions. SPR sensors based on both direct (with the immobilization of the antibody) and competitive (with the immobilization of the antigen) methods did not allow the detection of ampicillin. Therefore, a sandwich-based sensor was developed which showed a good linear response towards ampicillin between 10−3 and 10−1 M, a measurement time of ≤20 min and a high selectivity both towards β-lactam antibiotics and antibiotics of different classes. Full article
(This article belongs to the Special Issue Next-Generation Immunosensors)
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2095 KiB  
Article
Implementing Silicon Nanoribbon Field-Effect Transistors as Arrays for Multiple Ion Detection
by Ralph L. Stoop, Mathias Wipf, Steffen Müller, Kristine Bedner, Iain A. Wright, Colin J. Martin, Edwin C. Constable, Axel Fanget, Christian Schönenberger and Michel Calame
Biosensors 2016, 6(2), 21; https://doi.org/10.3390/bios6020021 - 6 May 2016
Cited by 11 | Viewed by 7690
Abstract
Ionic gradients play a crucial role in the physiology of the human body, ranging from metabolism in cells to muscle contractions or brain activities. To monitor these ions, inexpensive, label-free chemical sensing devices are needed. Field-effect transistors (FETs) based on silicon (Si) nanowires [...] Read more.
Ionic gradients play a crucial role in the physiology of the human body, ranging from metabolism in cells to muscle contractions or brain activities. To monitor these ions, inexpensive, label-free chemical sensing devices are needed. Field-effect transistors (FETs) based on silicon (Si) nanowires or nanoribbons (NRs) have a great potential as future biochemical sensors as they allow for the integration in microscopic devices at low production costs. Integrating NRs in dense arrays on a single chip expands the field of applications to implantable electrodes or multifunctional chemical sensing platforms. Ideally, such a platform is capable of detecting numerous species in a complex analyte. Here, we demonstrate the basis for simultaneous sodium and fluoride ion detection with a single sensor chip consisting of arrays of gold-coated SiNR FETs. A microfluidic system with individual channels allows modifying the NR surfaces with self-assembled monolayers of two types of ion receptors sensitive to sodium and fluoride ions. The functionalization procedure results in a differential setup having active fluoride- and sodium-sensitive NRs together with bare gold control NRs on the same chip. Comparing functionalized NRs with control NRs allows the compensation of non-specific contributions from changes in the background electrolyte concentration and reveals the response to the targeted species. Full article
(This article belongs to the Special Issue Field-Effect Transistor Biosensors)
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914 KiB  
Article
Real-Time Detection of Staphylococcus Aureus Using Whispering Gallery Mode Optical Microdisks
by Hala Ghali, Hicham Chibli, Jay L. Nadeau, Pablo Bianucci and Yves-Alain Peter
Biosensors 2016, 6(2), 20; https://doi.org/10.3390/bios6020020 - 3 May 2016
Cited by 47 | Viewed by 8377
Abstract
Whispering Gallery Mode (WGM) microresonators have recently been studied as a means to achieve real-time label-free detection of biological targets such as virus particles, specific DNA sequences, or proteins. Due to their high quality (Q) factors, WGM resonators can be highly sensitive. A [...] Read more.
Whispering Gallery Mode (WGM) microresonators have recently been studied as a means to achieve real-time label-free detection of biological targets such as virus particles, specific DNA sequences, or proteins. Due to their high quality (Q) factors, WGM resonators can be highly sensitive. A biosensor also needs to be selective, requiring proper functionalization of its surface with the appropriate ligand that will attach the biomolecule of interest. In this paper, WGM microdisks are used as biosensors for detection of Staphylococcus aureus. The microdisks are functionalized with LysK, a phage protein specific for staphylococci at the genus level. A binding event on the surface shifts the resonance peak of the microdisk resonator towards longer wavelengths. This reactive shift can be used to estimate the surface density of bacteria that bind to the surface of the resonator. The limit of detection of a microdisk with a Q-factor around 104 is on the order of 5 pg/mL, corresponding to 20 cells. No binding of Escherichia coli to the resonators is seen, supporting the specificity of the functionalization scheme. Full article
(This article belongs to the Special Issue Novel Nanobiosensors for Environmental, Food and Clinical Analyses)
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2445 KiB  
Article
Semi-Quantitative Method for Streptococci Magnetic Detection in Raw Milk
by Carla Duarte, Tiago Costa, Carla Carneiro, Rita Soares, Andrei Jitariu, Susana Cardoso, Moisés Piedade, Ricardo Bexiga and Paulo Freitas
Biosensors 2016, 6(2), 19; https://doi.org/10.3390/bios6020019 - 27 Apr 2016
Cited by 30 | Viewed by 10076
Abstract
Bovine mastitis is the most costly disease for dairy farmers and the most frequent reason for the use of antibiotics in dairy cattle; thus, control measures to detect and prevent mastitis are crucial for dairy farm sustainability. The aim of this study was [...] Read more.
Bovine mastitis is the most costly disease for dairy farmers and the most frequent reason for the use of antibiotics in dairy cattle; thus, control measures to detect and prevent mastitis are crucial for dairy farm sustainability. The aim of this study was to develop and validate a sensitive method to magnetically detect Streptococcus agalactiae (a Group B streptococci) and Streptococcus uberis in raw milk samples. Mastitic milk samples were collected aseptically from 44 cows with subclinical mastitis, from 11 Portuguese dairy farms. Forty-six quarter milk samples were selected based on bacterial identification by conventional microbiology. All samples were submitted to PCR analysis. In parallel, these milk samples were mixed with a solution combining specific antibodies and magnetic nanoparticles, to be analyzed using a lab-on-a-chip magnetoresistive cytometer, with microfluidic sample handling. This paper describes a point of care methodology used for detection of bacteria, including analysis of false positive/negative results. This immunological recognition was able to detect bacterial presence in samples spiked above 100 cfu/mL, independently of antibody and targeted bacteria used in this work. Using PCR as a reference, this method correctly identified 73% of positive samples for streptococci species with an anti-S. agalactiae antibody, and 41% of positive samples for an anti-GB streptococci antibody. Full article
(This article belongs to the Special Issue Advances in Lab-on-Chip Devices)
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3866 KiB  
Review
Current-Induced Transistor Sensorics with Electrogenic Cells
by Peter Fromherz
Biosensors 2016, 6(2), 18; https://doi.org/10.3390/bios6020018 - 25 Apr 2016
Cited by 9 | Viewed by 6742
Abstract
The concepts of transistor recording of electroactive cells are considered, when the response is determined by a current-induced voltage in the electrolyte due to cellular activity. The relationship to traditional transistor recording, with an interface-induced response due to interactions with the open gate [...] Read more.
The concepts of transistor recording of electroactive cells are considered, when the response is determined by a current-induced voltage in the electrolyte due to cellular activity. The relationship to traditional transistor recording, with an interface-induced response due to interactions with the open gate oxide, is addressed. For the geometry of a cell-substrate junction, the theory of a planar core-coat conductor is described with a one-compartment approximation. The fast electrical relaxation of the junction and the slow change of ion concentrations are pointed out. On that basis, various recording situations are considered and documented by experiments. For voltage-gated ion channels under voltage clamp, the effects of a changing extracellular ion concentration and the enhancement/depletion of ion conductances in the adherent membrane are addressed. Inhomogeneous ion conductances are crucial for transistor recording of neuronal action potentials. For a propagating action potential, the effects of an axon-substrate junction and the surrounding volume conductor are distinguished. Finally, a receptor-transistor-sensor is described, where the inhomogeneity of a ligand–activated ion conductance is achieved by diffusion of the agonist and inactivation of the conductance. Problems with regard to a development of reliable biosensors are mentioned. Full article
(This article belongs to the Special Issue Field-Effect Transistor Biosensors)
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2886 KiB  
Article
Electronic Biosensing with Functionalized rGO FETs
by Ciril Reiner-Rozman, Caroline Kotlowski and Wolfgang Knoll
Biosensors 2016, 6(2), 17; https://doi.org/10.3390/bios6020017 - 22 Apr 2016
Cited by 45 | Viewed by 10858
Abstract
In the following we give a short summary of examples for biosensor concepts in areas in which reduced graphene oxide-based electronic devices can be developed into new classes of biosensors, which are highly sensitive, label-free, disposable and cheap, with electronic signals that are [...] Read more.
In the following we give a short summary of examples for biosensor concepts in areas in which reduced graphene oxide-based electronic devices can be developed into new classes of biosensors, which are highly sensitive, label-free, disposable and cheap, with electronic signals that are easy to analyze and interpret, suitable for multiplexed operation and for remote control, compatible with NFC technology, etc., and in many cases a clear and promising alternative to optical sensors. The presented areas concern sensing challenges in medical diagnostics with an example for detecting general antibody-antigen interactions, for the monitoring of toxins and pathogens in food and feed stuff, exemplified by the detection of aflatoxins, and the area of smell sensors, which are certainly the most exciting development as there are very few existing examples in which the typically small and hydrophobic odorant molecules can be detected by other means. The example given here concerns the recording of a honey flavor (and a cancer marker for neuroblastoma), homovanillic acid, by the odorant binding protein OBP 14 from the honey bee, immobilized on the reduced graphene oxide gate of an FET sensor. Full article
(This article belongs to the Special Issue Field-Effect Transistor Biosensors)
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1631 KiB  
Review
Harnessing Aptamers to Overcome Challenges in Gluten Detection
by Rebeca Miranda-Castro, Noemí De-los-Santos-Álvarez, Arturo J. Miranda-Ordieres and María Jesús Lobo-Castañón
Biosensors 2016, 6(2), 16; https://doi.org/10.3390/bios6020016 - 20 Apr 2016
Cited by 20 | Viewed by 9332
Abstract
Celiac disease is a lifelong autoimmune disorder triggered by foods containing gluten, the storage protein in wheat, rye, and barley. The rapidly escalating number of patients diagnosed with this disease poses a great challenge to both food industry and authorities to guarantee food [...] Read more.
Celiac disease is a lifelong autoimmune disorder triggered by foods containing gluten, the storage protein in wheat, rye, and barley. The rapidly escalating number of patients diagnosed with this disease poses a great challenge to both food industry and authorities to guarantee food safety for all. Therefore, intensive efforts are being made to establish minimal disease-eliciting doses of gluten and consequently to improve gluten-free labeling. These efforts depend to a high degree on the availability of methods capable of detecting the protein in food samples at levels as low as possible. Current analytical approaches rely on the use of antibodies as selective recognition elements. With limited sensitivity, these methods exhibit some deficiencies that compromise the accuracy of the obtained results. Aptamers provide an ideal alternative for designing biosensors for fast and selective measurement of gluten in foods. This article highlights the challenges in gluten detection, the current status of the use of aptamers for solving this problem, and what remains to be done to move these systems into commercial applications. Full article
(This article belongs to the Special Issue Aptamer Sensors)
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3981 KiB  
Article
AC and Phase Sensing of Nanowires for Biosensing
by Marco Crescentini, Michele Rossi, Peter Ashburn, Marta Lombardini, Enrico Sangiorgi, Hywel Morgan and Marco Tartagni
Biosensors 2016, 6(2), 15; https://doi.org/10.3390/bios6020015 - 19 Apr 2016
Cited by 13 | Viewed by 7612
Abstract
Silicon nanowires are label-free sensors that allow real-time measurements. They are economical and pave the road for point-of-care applications but require complex readout and skilled personnel. We propose a new model and technique for sensing nanowire sensors using alternating currents (AC) to capture [...] Read more.
Silicon nanowires are label-free sensors that allow real-time measurements. They are economical and pave the road for point-of-care applications but require complex readout and skilled personnel. We propose a new model and technique for sensing nanowire sensors using alternating currents (AC) to capture both magnitude and phase information from the sensor. This approach combines the advantages of complex impedance spectroscopy with the noise reduction performances of lock-in techniques. Experimental results show how modifications of the sensors with different surface chemistries lead to the same direct-current (DC) response but can be discerned using the AC approach. Full article
(This article belongs to the Special Issue Micro- and Nano-Bio-Interfaces)
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2704 KiB  
Review
Droplet-based Biosensing for Lab-on-a-Chip, Open Microfluidics Platforms
by Piyush Dak, Aida Ebrahimi, Vikhram Swaminathan, Carlos Duarte-Guevara, Rashid Bashir and Muhammad A. Alam
Biosensors 2016, 6(2), 14; https://doi.org/10.3390/bios6020014 - 14 Apr 2016
Cited by 52 | Viewed by 12132
Abstract
Low cost, portable sensors can transform health care by bringing easily available diagnostic devices to low and middle income population, particularly in developing countries. Sample preparation, analyte handling and labeling are primary cost concerns for traditional lab-based diagnostic systems. Lab-on-a-chip (LoC) platforms based [...] Read more.
Low cost, portable sensors can transform health care by bringing easily available diagnostic devices to low and middle income population, particularly in developing countries. Sample preparation, analyte handling and labeling are primary cost concerns for traditional lab-based diagnostic systems. Lab-on-a-chip (LoC) platforms based on droplet-based microfluidics promise to integrate and automate these complex and expensive laboratory procedures onto a single chip; the cost will be further reduced if label-free biosensors could be integrated onto the LoC platforms. Here, we review some recent developments of label-free, droplet-based biosensors, compatible with “open” digital microfluidic systems. These low-cost droplet-based biosensors overcome some of the fundamental limitations of the classical sensors, enabling timely diagnosis. We identify the key challenges that must be addressed to make these sensors commercially viable and summarize a number of promising research directions. Full article
(This article belongs to the Special Issue Field-Effect Transistor Biosensors)
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1769 KiB  
Article
Infrared Spectroscopy of Bilberry Extract Water-in-Oil Emulsions: Sensing the Water-Oil Interface
by Johannes Kiefer, Kerstin Frank, Florian M. Zehentbauer and Heike P. Schuchmann
Biosensors 2016, 6(2), 13; https://doi.org/10.3390/bios6020013 - 14 Apr 2016
Cited by 26 | Viewed by 12084
Abstract
Water-in-oil (w/o) emulsions are of great interest in many areas of the life sciences, including food technology, bioprocess engineering, and pharmaceuticals. Such emulsions are complex multi-component systems and the molecular mechanisms which lead to a stable emulsion are yet to be fully understood. [...] Read more.
Water-in-oil (w/o) emulsions are of great interest in many areas of the life sciences, including food technology, bioprocess engineering, and pharmaceuticals. Such emulsions are complex multi-component systems and the molecular mechanisms which lead to a stable emulsion are yet to be fully understood. In this work, attenuated total reflection (ATR) infrared (IR) spectroscopy is applied to a series of w/o emulsions of an aqueous anthocyanin-rich bilberry extract dispersed in a medium chain triglyceride (MCT) oil phase. The content of the emulsifier polyglycerin-polyricinoleat (PGPR) has been varied systematically in order to investigate whether or not its concentration has an impact on the molecular stabilization mechanisms. The molecular stabilization is accessed by a careful analysis of the IR spectrum, where changes in the vibrational frequencies and signal strengths indicate alterations of the molecular environment at the water/oil interface. The results suggest that adding emulsifier in excess of 1% by weight does not lead to an enhanced stabilization of the emulsion. Full article
(This article belongs to the Special Issue Raman and IR Spectroscopic Sensing)
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188 KiB  
Commentary
Epigenome: A Biomarker or Screening Tool to Evaluate Health Impact of Cumulative Exposure to Chemical and Non-Chemical Stressors
by Kenneth Olden, Yu-Sheng Lin and David Bussard
Biosensors 2016, 6(2), 12; https://doi.org/10.3390/bios6020012 - 1 Apr 2016
Cited by 4 | Viewed by 6060
Abstract
Current risk assessment practices and toxicity information are hard to utilize for assessing the health impact of combined or cumulative exposure to multiple chemical and non-chemical stressors encountered in the “real world” environment. Non-chemical stressors such as heat, radiation, noise, humidity, bacterial and [...] Read more.
Current risk assessment practices and toxicity information are hard to utilize for assessing the health impact of combined or cumulative exposure to multiple chemical and non-chemical stressors encountered in the “real world” environment. Non-chemical stressors such as heat, radiation, noise, humidity, bacterial and viral agents, and social factors, like stress related to violence and socioeconomic position generally cannot be currently incorporated into the risk assessment paradigm. The Science and Decisions report released by the National Research Council (NRC) in 2009 emphasized the need to characterize the effects of multiple stressors, both chemical and non-chemical exposures. One impediment to developing information relating such non-chemical stressors to health effects and incorporating them into cumulative assessment has been the lack of analytical tools to easily and quantitatively monitor the cumulative exposure to combined effects of stressors over the life course. Full article
(This article belongs to the Special Issue Biosensors in Environmental Studies)
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Article
Measurement of Rapid Amiloride-Dependent pH Changes at the Cell Surface Using a Proton-Sensitive Field-Effect Transistor
by Daniel Schaffhauser, Michael Fine, Miyuki Tabata, Tatsuro Goda and Yuji Miyahara
Biosensors 2016, 6(2), 11; https://doi.org/10.3390/bios6020011 - 30 Mar 2016
Cited by 18 | Viewed by 7421
Abstract
We present a novel method for the rapid measurement of pH fluxes at close proximity to the surface of the plasma membrane in mammalian cells using an ion-sensitive field-effect transistor (ISFET). In conjuction with an efficient continuous superfusion system, the ISFET sensor was [...] Read more.
We present a novel method for the rapid measurement of pH fluxes at close proximity to the surface of the plasma membrane in mammalian cells using an ion-sensitive field-effect transistor (ISFET). In conjuction with an efficient continuous superfusion system, the ISFET sensor was capable of recording rapid changes in pH at the cells’ surface induced by intervals of ammonia loading and unloading, even when using highly buffered solutions. Furthermore, the system was able to isolate physiologically relevant signals by not only detecting the transients caused by ammonia loading and unloading, but display steady-state signals as would be expected by a proton transport-mediated influence on the extracellular proton-gradient. Proof of concept was demonstrated through the use of 5-(N-ethyl-N-isopropyl)amiloride (EIPA), a small molecule inhibitor of sodium/hydrogen exchangers (NHE). As the primary transporter responsible for proton balance during cellular regulation of pH, non-electrogenic NHE transport is notoriously difficult to detect with traditional methods. Using the NHE positive cell lines, Chinese hamster ovary (CHO) cells and NHE3-reconstituted mouse skin fibroblasts (MSF), the sensor exhibited a significant response to EIPA inhibition, whereas NHE-deficient MSF cells were unaffected by application of the inhibitor. Full article
(This article belongs to the Special Issue Field-Effect Transistor Biosensors)
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