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Biosensors
Volume 9
Issue 3
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Biosensors, Volume 9, Issue 3 (September 2019) – 30 articles

Cover Story (view full-size image): This research aims to minimize the power consumption of the organic optoelectronic pulse meter biosensor for long-term monitoring of the PPG waveforms wirelessly. A reflectance-type optoelectronic pulse meter composed of a red organic light-emitting diode (OLED) and an organic photodiode (OPD) fabricated monolithically on a glass substrate was proposed to measure the PPG signals. Two design structures with different OLED areas and gaps between an OLED and an OPD were examined for minimizing the power consumption and noise level of the biosensor pulse meter and evaluated using the PPG signal, which was successfully collected from a fingertip. The proposed reflectance-based organic pulse meter was operated successfully with an ultra-low power consumption down to 8 μW at 18 dB SNR, and with a clear PPG signal up to 46 dB SNR at a constant current of 93.6 μA. View this paper.
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17 pages, 3639 KiB  
Article
Flexible PET/ITO/Ag SERS Platform for Label-Free Detection of Pesticides
by Ariadna B. Nowicka, Marta Czaplicka, Aneta A. Kowalska, Tomasz Szymborski and Agnieszka Kamińska
Biosensors 2019, 9(3), 111; https://doi.org/10.3390/bios9030111 - 19 Sep 2019
Cited by 29 | Viewed by 6715
Abstract
We show a new type of elastic surface-enhanced Raman spectroscopy (SERS) platform made of poly(ethylene terephthalate) (PET) covered with a layer of indium tin oxide (ITO). This composite is subjected to dielectric barrier discharge (DBD) that develops the active surface of the PET/ITO [...] Read more.
We show a new type of elastic surface-enhanced Raman spectroscopy (SERS) platform made of poly(ethylene terephthalate) (PET) covered with a layer of indium tin oxide (ITO). This composite is subjected to dielectric barrier discharge (DBD) that develops the active surface of the PET/ITO foil. To enhance the Raman signal, a modified composite was covered with a thin layer of silver using the physical vapor deposition (PVD) technique. The SERS platform was used for measurements of para-mercaptobenzoic acid (p-MBA) and popular pesticides, i.e., Thiram and Carbaryl. The detection and identification of pesticides on the surface of fruits and vegetables is a crucial issue due to extensive use of those chemical substances for plant fungicide and insecticide protection. Therefore, the developed PET/ITO/Ag SERS platform was dedicated to quantitative analysis of selected pesticides, i.e., Thiram and Carbaryl from fruits. The presented SERS platform exhibits excellent enhancement and reproducibility of the Raman signal, which enables the trace analysis of these pesticides in the range up to their maximum residues limit. Based on the constructed calibration curves, the pesticide concentrations from the skin of apples was estimated as 2.5 µg/mL and 0.012 µg/mL for Thiram and Carbaryl, respectively. Additionally, the PET/ITO/Ag SERS platform satisfies other spectroscopic properties required for trace pesticide analysis e.g., ease, cost-effective method of preparation, and specially designed physical properties, especially flexibility and transparency, that broaden the sampling versatility to irregular surfaces. Full article
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25 pages, 7673 KiB  
Review
Latest Trends in Biosensing for Microphysiological Organs-on-a-Chip and Body-on-a-Chip Systems
by Sebastian Rudi Adam Kratz, Gregor Höll, Patrick Schuller, Peter Ertl and Mario Rothbauer
Biosensors 2019, 9(3), 110; https://doi.org/10.3390/bios9030110 - 19 Sep 2019
Cited by 77 | Viewed by 12752
Abstract
Organs-on-chips are considered next generation in vitro tools capable of recreating in vivo like, physiological-relevant microenvironments needed to cultivate 3D tissue-engineered constructs (e.g., hydrogel-based organoids and spheroids) as well as tissue barriers. These microphysiological systems are ideally suited to (a) reduce animal testing [...] Read more.
Organs-on-chips are considered next generation in vitro tools capable of recreating in vivo like, physiological-relevant microenvironments needed to cultivate 3D tissue-engineered constructs (e.g., hydrogel-based organoids and spheroids) as well as tissue barriers. These microphysiological systems are ideally suited to (a) reduce animal testing by generating human organ models, (b) facilitate drug development and (c) perform personalized medicine by integrating patient-derived cells and patient-derived induced pluripotent stem cells (iPSCs) into microfluidic devices. An important aspect of any diagnostic device and cell analysis platform, however, is the integration and application of a variety of sensing strategies to provide reliable, high-content information on the health status of the in vitro model of choice. To overcome the analytical limitations of organs-on-a-chip systems a variety of biosensors have been integrated to provide continuous data on organ-specific reactions and dynamic tissue responses. Here, we review the latest trends in biosensors fit for monitoring human physiology in organs-on-a-chip systems including optical and electrochemical biosensors. Full article
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16 pages, 1579 KiB  
Article
Characterization of Binding of Magnetic Nanoparticles to Rolling Circle Amplification Products by Turn-On Magnetic Assay
by Sobhan Sepehri, Björn Agnarsson, Teresa Zardán Gómez de la Torre, Justin F. Schneiderman, Jakob Blomgren, Aldo Jesorka, Christer Johansson, Mats Nilsson, Jan Albert, Maria Strømme, Dag Winkler and Alexei Kalaboukhov
Biosensors 2019, 9(3), 109; https://doi.org/10.3390/bios9030109 - 17 Sep 2019
Cited by 3 | Viewed by 5213
Abstract
The specific binding of oligonucleotide-tagged 100 nm magnetic nanoparticles (MNPs) to rolling circle products (RCPs) is investigated using our newly developed differential homogenous magnetic assay (DHMA). The DHMA measures ac magnetic susceptibility from a test and a control samples simultaneously and eliminates magnetic [...] Read more.
The specific binding of oligonucleotide-tagged 100 nm magnetic nanoparticles (MNPs) to rolling circle products (RCPs) is investigated using our newly developed differential homogenous magnetic assay (DHMA). The DHMA measures ac magnetic susceptibility from a test and a control samples simultaneously and eliminates magnetic background signal. Therefore, the DHMA can reveal details of binding kinetics of magnetic nanoparticles at very low concentrations of RCPs. From the analysis of the imaginary part of the DHMA signal, we find that smaller MNPs in the particle ensemble bind first to the RCPs. When the RCP concentration increases, we observe the formation of agglomerates, which leads to lower number of MNPs per RCP at higher concentrations of RCPs. The results thus indicate that a full frequency range of ac susceptibility observation is necessary to detect low concentrations of target RCPs and a long amplification time is not required as it does not significantly increase the number of MNPs per RCP. The findings are critical for understanding the underlying microscopic binding process for improving the assay performance. They furthermore suggest DHMA is a powerful technique for dynamically characterizing the binding interactions between MNPs and biomolecules in fluid volumes. Full article
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14 pages, 6595 KiB  
Article
Use of an Insulation Layer on the Connection Tracks of a Biosensor with Coplanar Electrodes to Increase the Normalized Impedance Variation
by Arthur Luiz Alves de Araujo, Julien Claudel, Djilali Kourtiche and Mustapha Nadi
Biosensors 2019, 9(3), 108; https://doi.org/10.3390/bios9030108 - 16 Sep 2019
Cited by 7 | Viewed by 5171
Abstract
New technologies, such as biosensors and lab-on-a-chip, are reducing time consumption and costs for the detection and characterization of biological cells. One challenge is to detect and characterize cells and bacteria one by one or at a very low concentration. In this case, [...] Read more.
New technologies, such as biosensors and lab-on-a-chip, are reducing time consumption and costs for the detection and characterization of biological cells. One challenge is to detect and characterize cells and bacteria one by one or at a very low concentration. In this case, measurements have very low variations that can be difficult to detect. In this article, the use of an insulation layer on the connection tracks of a biosensor with coplanar electrodes is proposed to improve a biosensor previously developed. The impedance spectroscopy technique was used to analyze the influence of the insulation layer on the cutoff frequencies and on the normalized impedance variation. This solution does not induce changes in the cutoff frequencies, though it permits improving the normalized impedance variations, compared to the same biosensor without the insulation layer. Full article
(This article belongs to the Special Issue Biomaterials and Biosensors: Current Advancements)
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13 pages, 3089 KiB  
Article
Wireless Direct Microampere Current in Wound Healing: Clinical and Immunohistological Data from Two Single Case Reports
by George Lagoumintzis, Zoi Zagoriti, Mogens S. Jensen, Theodoros Argyrakos, Constantinos Koutsojannis and Konstantinos Poulas
Biosensors 2019, 9(3), 107; https://doi.org/10.3390/bios9030107 - 5 Sep 2019
Cited by 12 | Viewed by 7911
Abstract
Chronic pressure ulcers are hard-to-heal wounds that decrease the patient’s quality of life. Wireless Micro Current Stimulation (WMCS) is an innovative, non-invasive, similar to electrode-based electrostimulation (ES) technology, that generates and transfers ions that are negatively-charged to the injured tissue, using accessible air [...] Read more.
Chronic pressure ulcers are hard-to-heal wounds that decrease the patient’s quality of life. Wireless Micro Current Stimulation (WMCS) is an innovative, non-invasive, similar to electrode-based electrostimulation (ES) technology, that generates and transfers ions that are negatively-charged to the injured tissue, using accessible air gases as a transfer medium. WMCS is capable of generating similar tissue potentials, as electrode-based ES, for injured tissue. Here, through immunohistochemistry, we intended to characterize the induced tissue healing biological mechanisms that occur during WMCS therapy. Two single cases of bedridden due to serious stroke white men with chronic non-healing pressure ulcers have been treated with WMCS technology. WMCS suppresses inflammatory responses by decreasing the aggregation of granulocytes, followed by stimulating myofibroblastic activity and a new formation of collagen fibers, as depicted by immunohistochemistry. As a result, WMCS provides a special adjunct or stand-alone therapy choice for chronic and non-healing injuries, similar to electrode-based ES, but with added (i.e., contactless) benefits towards its establishment as a routine clinical wound healing regime. Full article
(This article belongs to the Special Issue Bioelectric Sensors)
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9 pages, 1250 KiB  
Article
Evaluation of 3-Chlorobenzoate 1,2-Dioxygenase Inhibition by 2- and 4-Chlorobenzoate with a Cell-Based Technique
by Elena V. Emelyanova and Inna P. Solyanikova
Biosensors 2019, 9(3), 106; https://doi.org/10.3390/bios9030106 - 5 Sep 2019
Cited by 6 | Viewed by 4735
Abstract
The electrochemical reactor microbial sensor with the Clark oxygen electrode as the transducer was used for investigation of the competition between 3-chlorobenzoate (3-CBA) and its analogues, 2- and 4-chlorobenzoate (2-CBA and 4-CBA), for 3-chlorobenzoate-1,2-dioxygenase (3-CBDO) of Rhodococcus opacus 1CP cells. The change in [...] Read more.
The electrochemical reactor microbial sensor with the Clark oxygen electrode as the transducer was used for investigation of the competition between 3-chlorobenzoate (3-CBA) and its analogues, 2- and 4-chlorobenzoate (2-CBA and 4-CBA), for 3-chlorobenzoate-1,2-dioxygenase (3-CBDO) of Rhodococcus opacus 1CP cells. The change in respiration of freshly harvested R. opacus 1CP cells in response to 3-CBA served as an indicator of 3-CBDO activity. The results obtained confirmed inducibility of 3-CBDO. Sigmoidal dependency of the rate of the enzymatic reaction on the concentration of 3-CBA was obtained and positive kinetic cooperativity by a substrate was shown for 3-CBDO. The Hill concentration constant, S0.5, and the constant of catalytic activity, Vmax, were determined. Inhibition of the rate of enzymatic reaction by excess substrate, 3-CBA, was observed. Associative (competitive inhibition according to classic classification) and transient types of the 3-CBA-1,2-DO inhibition by 2-CBA and 4-CBA, respectively, were found. The kinetic parameters such as S0.5i and Vmaxi were also estimated for 2-CBA and 4-CBA. The disappearance of the S-shape of the curve of the V versus S dependence for 3-CBDO in the presence of 4-CBA was assumed to imply that 4-chlorobenzoate had no capability to be catalytically transformed by 3-chlorobenzoate-1,2-dioxygenase of Rhodococcus opacus 1CP cells. Full article
(This article belongs to the Special Issue Dedication to TUT President Isao Karube: Microbial Biosensors)
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20 pages, 1825 KiB  
Article
Evaluation of In-Flow Magnetoresistive Chip Cell—Counter as a Diagnostic Tool
by Manon Giraud, François-Damien Delapierre, Anne Wijkhuisen, Pierre Bonville, Mathieu Thévenin, Gregory Cannies, Marc Plaisance, Elodie Paul, Eric Ezan, Stéphanie Simon, Claude Fermon, Cécile Féraudet-Tarisse and Guénaëlle Jasmin-Lebras
Biosensors 2019, 9(3), 105; https://doi.org/10.3390/bios9030105 - 31 Aug 2019
Cited by 9 | Viewed by 7797
Abstract
Inexpensive simple medical devices allowing fast and reliable counting of whole cells are of interest for diagnosis and treatment monitoring. Magnetic-based labs on a chip are one of the possibilities currently studied to address this issue. Giant magnetoresistance (GMR) sensors offer both great [...] Read more.
Inexpensive simple medical devices allowing fast and reliable counting of whole cells are of interest for diagnosis and treatment monitoring. Magnetic-based labs on a chip are one of the possibilities currently studied to address this issue. Giant magnetoresistance (GMR) sensors offer both great sensitivity and device integrability with microfluidics and electronics. When used on a dynamic system, GMR-based biochips are able to detect magnetically labeled individual cells. In this article, a rigorous evaluation of the main characteristics of this magnetic medical device (specificity, sensitivity, time of use and variability) are presented and compared to those of both an ELISA test and a conventional flow cytometer, using an eukaryotic malignant cell line model in physiological conditions (NS1 murine cells in phosphate buffer saline). We describe a proof of specificity of a GMR sensor detection of magnetically labeled cells. The limit of detection of the actual system was shown to be similar to the ELISA one and 10 times higher than the cytometer one. Full article
(This article belongs to the Special Issue Microfluidics for Biosensing and Diagnostics)
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18 pages, 2340 KiB  
Article
Surface Functionalization by Hydrophobin-EPSPS Fusion Protein Allows for the Fast and Simple Detection of Glyphosate
by Julia Döring, David Rettke, Gerhard Rödel, Tilo Pompe and Kai Ostermann
Biosensors 2019, 9(3), 104; https://doi.org/10.3390/bios9030104 - 29 Aug 2019
Cited by 8 | Viewed by 6650
Abstract
Glyphosate, the most widely used pesticide worldwide, is under debate due to its potentially cancerogenic effects and harmful influence on biodiversity and environment. Therefore, the detection of glyphosate in water, food or environmental probes is of high interest. Currently detection of glyphosate usually [...] Read more.
Glyphosate, the most widely used pesticide worldwide, is under debate due to its potentially cancerogenic effects and harmful influence on biodiversity and environment. Therefore, the detection of glyphosate in water, food or environmental probes is of high interest. Currently detection of glyphosate usually requires specialized, costly instruments, is labor intensive and time consuming. Here we present a fast and simple method to detect glyphosate in the nanomolar range based on the surface immobilization of glyphosate’s target enzyme 5-enolpyruvylshikimate-3-phosphate synthase (EPSPS) via fusion to the hydrophobin Ccg2 and determination of enzyme activity with a malachite green assay, which is a common photometric technique to measure inorganic phosphate (Pi). The assay demonstrates a new approach for a fast and simple detection of pesticides. Full article
(This article belongs to the Special Issue Functional Nanomaterials for Biosensing and Bioimaging)
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13 pages, 2901 KiB  
Article
Silk Fibroin-Sheathed Conducting Polymer Wires as Organic Connectors for Biosensors
by Yanke Jiang, Meng Xu and Vamsi K Yadavalli
Biosensors 2019, 9(3), 103; https://doi.org/10.3390/bios9030103 - 28 Aug 2019
Cited by 18 | Viewed by 6521
Abstract
Conductive polymers, owing to their tunable mechanical and electrochemical properties, are viable candidates to replace metallic components for the development of biosensors and bioelectronics. However, conducting fibers/wires fabricated from these intrinsically conductive and mechanically flexible polymers are typically produced without protective coatings for [...] Read more.
Conductive polymers, owing to their tunable mechanical and electrochemical properties, are viable candidates to replace metallic components for the development of biosensors and bioelectronics. However, conducting fibers/wires fabricated from these intrinsically conductive and mechanically flexible polymers are typically produced without protective coatings for physiological environments. Providing sheathed conductive fibers/wires can open numerous opportunities for fully organic biodevices. In this work, we report on a facile method to fabricate core-sheath poly(3,4-ethylenedioxythiophene):poly(styrenesulfonate) PEDOT:PSS-silk fibroin conductive wires. The conductive wires are formed through a wet-spinning process, and then coated with an optically transparent, photocrosslinkable silk fibroin sheath for insulation and protection in a facile and scalable process. The sheathed fibers were evaluated for their mechanical and electrical characteristics and overall stability. These wires can serve as flexible connectors to an organic electrode biosensor. The entire, fully organic, biodegradable, and free-standing flexible biosensor demonstrated a high sensitivity and rapid response for the detection of ascorbic acid as a model analyte. The entire system can be proteolytically biodegraded in a few weeks. Such organic systems can therefore provide promising solutions to address challenges in transient devices and environmental sustainability. Full article
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30 pages, 1445 KiB  
Review
Overview of Optical and Electrochemical Alkaline Phosphatase (ALP) Biosensors: Recent Approaches in Cells Culture Techniques
by Thanih Balbaied and Eric Moore
Biosensors 2019, 9(3), 102; https://doi.org/10.3390/bios9030102 - 23 Aug 2019
Cited by 39 | Viewed by 15829
Abstract
Alkaline phosphatase (ALP), which catalyzes the dephosphorylation process of proteins, nucleic acids, and small molecules, can be found in a variety of tissues (intestine, liver, bone, kidney, and placenta) of almost all living organisms. This enzyme has been extensively used as a biomarker [...] Read more.
Alkaline phosphatase (ALP), which catalyzes the dephosphorylation process of proteins, nucleic acids, and small molecules, can be found in a variety of tissues (intestine, liver, bone, kidney, and placenta) of almost all living organisms. This enzyme has been extensively used as a biomarker in enzyme immunoassays and molecular biology. ALP is also one of the most commonly assayed enzymes in routine clinical practice. Due to its close relation to a variety of pathological processes, ALP’s abnormal level is an important diagnostic biomarker of many human diseases, such as liver dysfunction, bone diseases, kidney acute injury, and cancer. Therefore, the development of convenient and reliable assay methods for monitoring ALP activity/level is extremely important and valuable, not only for clinical diagnoses but also in the area of biomedical research. This paper comprehensively reviews the strategies of optical and electrochemical detection of ALP and discusses the electrochemical techniques that have been addressed to make them suitable for ALP analysis in cell culture. Full article
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4 pages, 174 KiB  
Book Review
Advances in Nanosensors for Biological and Environmental Analysis: Book Review. Akash Deep, Sandeep Kumar (Eds.); Elsevier 2019; ISBN: 978-0-12-817456-2
by Ajeet Kaushik
Biosensors 2019, 9(3), 101; https://doi.org/10.3390/bios9030101 - 22 Aug 2019
Cited by 5 | Viewed by 4832
Abstract
A book entitled “Advances in Nanosensors for Biological and Environmental Analysis” published by Elsevier in 2019, is reviewed carefully and critically in this report. In this book, editors explored nanotechnology assisted approaches to develop smart and efficient nanosensors for biological and environmental analysis. [...] Read more.
A book entitled “Advances in Nanosensors for Biological and Environmental Analysis” published by Elsevier in 2019, is reviewed carefully and critically in this report. In this book, editors explored nanotechnology assisted approaches to develop smart and efficient nanosensors for biological and environmental analysis. Fundamental approaches to prototype development and a focus towards designing miniaturized sensing systems and for point-of-care application, along with considering commercial aspects are key features of this book. This book has potential to serve as a foundation platform for scholars of various disciplines to plan and manage multi-display research in the field of biomedical nanotechnology for diagnostics and environmental monitoring. Full article
13 pages, 4952 KiB  
Article
Gold Nanostar Colorimetric Detection of Fructosyl Valine as a Potential Future Point of Care Biosensor Candidate for Glycated Haemoglobin Detection
by Danielle Wingrove Mulder, Masauso Moses Phiri and Barend Christiaan Vorster
Biosensors 2019, 9(3), 100; https://doi.org/10.3390/bios9030100 - 14 Aug 2019
Cited by 15 | Viewed by 6856
Abstract
Diabetes Mellitus is a growing global concern. The current methods used to detect glycated haemoglobin are precise, however, utilise expensive equipment, reagents and consumables. These are luxuries which rural communities cannot access. The nanotechnology methods which have been developed for glycated haemoglobin detection [...] Read more.
Diabetes Mellitus is a growing global concern. The current methods used to detect glycated haemoglobin are precise, however, utilise expensive equipment, reagents and consumables. These are luxuries which rural communities cannot access. The nanotechnology methods which have been developed for glycated haemoglobin detection are predominantly electrochemically based, have complicated lengthy fabrication processes and utilise toxic chemicals. Here a fructosyl amino acid oxidase gold nanostar biosensor has been developed as a potential future point of care biosensor candidate for glycated haemoglobin detection. The workup done on this biosensor showed that it was able to give a spectrophotometric readout and colorimetric result with naked eye detection in blank serum spiked with fructosyl valine. Full article
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14 pages, 2937 KiB  
Article
Dielectrophoresis Multipath Focusing of Microparticles through Perforated Electrodes in Microfluidic Channels
by Anas Alazzam, Mohammad Al-Khaleel, Mohamed Kamel Riahi, Bobby Mathew, Amjad Gawanmeh and Vahé Nerguizian
Biosensors 2019, 9(3), 99; https://doi.org/10.3390/bios9030099 - 7 Aug 2019
Cited by 2 | Viewed by 4934
Abstract
This paper presents focusing of microparticles in multiple paths within the direction of the flow using dielectrophoresis. The focusing of microparticles is realized through partially perforated electrodes within the microchannel. A continuous electrode on the top surface of the microchannel is considered, while [...] Read more.
This paper presents focusing of microparticles in multiple paths within the direction of the flow using dielectrophoresis. The focusing of microparticles is realized through partially perforated electrodes within the microchannel. A continuous electrode on the top surface of the microchannel is considered, while the bottom side is made of a circular meshed perforated electrode. For the mathematical model of this microfluidic channel, inertia, buoyancy, drag and dielectrophoretic forces are brought up in the motion equation of the microparticles. The dielectrophoretic force is accounted for through a finite element discretization taking into account the perforated 3D geometry within the microchannel. An ordinary differential equation is solved to track the trajectories of the microparticles. For the case of continuous electrodes using the same mathematical model, the numerical simulation shows a very good agreement with the experiments, and this confirms the validation of focusing of microparticles within the proposed perforated electrode microchannel. Microparticles of silicon dioxide and polystyrene are used for this analysis. Their initial positions and radius, the Reynolds number, and the radius of the pore in perforated electrodes mainly conduct microparticles trajectories. Moreover, the radius of the pore of perforated electrode is the dominant factor in the steady state levitation height. Full article
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12 pages, 2600 KiB  
Article
An Electrocatalytic Screen-Printed Amperometric Sensor for the Selective Measurement of Thiamine (Vitamin B1) in Food Supplements
by Amy Smart, Kelly L. Westmacott, Adrian Crew, Olena Doran and John P. Hart
Biosensors 2019, 9(3), 98; https://doi.org/10.3390/bios9030098 - 6 Aug 2019
Cited by 13 | Viewed by 6570
Abstract
An electrocatalytic screen-printed sensor has been investigated for the measurement of the biologically important biomolecule vitamin B1 (thiamine) for the first time in food supplements. Under basic conditions, the vitamin was converted to its electrochemically active thiolate anion species. It was shown that [...] Read more.
An electrocatalytic screen-printed sensor has been investigated for the measurement of the biologically important biomolecule vitamin B1 (thiamine) for the first time in food supplements. Under basic conditions, the vitamin was converted to its electrochemically active thiolate anion species. It was shown that an electrocatalytic oxidation reaction occurred with the screen-printed carbon electrode containing the mediator cobalt phthalocyanine (CoPC-SPCE). This had the advantage of producing an analytical response current at an operating potential of 0 V vs. Ag/AgCl compared to +0.34 V obtained with plain SPCEs. This resulted in improved selectivity and limit of detection. Detailed studies on the underlying mechanism occurring with the sensor are reported in this paper. A linear response was obtained between 0.1 and 20 µg mL−1, which was suitable for the quantification of the vitamin in two commercial products containing vitamin B1. The mean recovery for a multivitamin tablet with a declared content of 5 mg was 101% (coefficient of variation (CV) of 9.6%). A multivitamin drink, which had a much lower concentration of vitamin B1 (0.22 mg/100 mL), gave a mean recovery of 93.3% (CV 7.2%). These results indicate that our sensor holds promise for quality control of food supplements and other food types. Full article
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13 pages, 3760 KiB  
Article
Multimodal Device for Real-Time Monitoring of Skin Oxygen Saturation and Microcirculation Function
by Uldis Rubins, Zbignevs Marcinkevics, Janis Cimurs, Inga Saknite, Edgars Kviesis-Kipge and Andris Grabovskis
Biosensors 2019, 9(3), 97; https://doi.org/10.3390/bios9030097 - 2 Aug 2019
Cited by 15 | Viewed by 6835
Abstract
The present study introduces a recently developed compact hybrid device for real-time monitoring of skin oxygen saturation and temperature distribution. The prototype involves a snapshot hyperspectral camera, multi-wavelength illuminator, thermal camera, and built-in computer with custom-developed software. To validate this device in-vivo we [...] Read more.
The present study introduces a recently developed compact hybrid device for real-time monitoring of skin oxygen saturation and temperature distribution. The prototype involves a snapshot hyperspectral camera, multi-wavelength illuminator, thermal camera, and built-in computer with custom-developed software. To validate this device in-vivo we performed upper arm vascular occlusion on eight healthy volunteers. Palm skin oxygen saturation maps were analyzed in real-time using k-means segmentation algorithm and two-layer optical diffuse model. The prototype system demonstrated a satisfying performance of skin hyperspectral measurements in the spectral range of 507–625 nm. The results confirmed the reliability of the proposed system for in-vivo assessment of skin hemoglobin saturation with oxygen and microcirculation. Full article
(This article belongs to the Special Issue Optical Diagnostics with Point-of-Care and Point-of-Need Applications)
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28 pages, 4205 KiB  
Review
Bio-Recognition in Spectroscopy-Based Biosensors for *Heavy Metals-Water and Waterborne Contamination Analysis
by Alessandra Aloisi, Antonio Della Torre, Angelantonio De Benedetto and Rosaria Rinaldi
Biosensors 2019, 9(3), 96; https://doi.org/10.3390/bios9030096 - 30 Jul 2019
Cited by 21 | Viewed by 8897
Abstract
Microsystems and biomolecules integration as well multiplexing determinations are key aspects of sensing devices in the field of heavy metal contamination monitoring. The present review collects the most relevant information about optical biosensors development in the last decade. Focus is put on analytical [...] Read more.
Microsystems and biomolecules integration as well multiplexing determinations are key aspects of sensing devices in the field of heavy metal contamination monitoring. The present review collects the most relevant information about optical biosensors development in the last decade. Focus is put on analytical characteristics and applications that are dependent on: (i) Signal transduction method (luminescence, colorimetry, evanescent wave (EW), surface-enhanced Raman spectroscopy (SERS), Förster resonance energy transfer (FRET), surface plasmon resonance (SPR); (ii) biorecognition molecules employed (proteins, nucleic acids, aptamers, and enzymes). The biosensing systems applied (or applicable) to water and milk samples will be considered for a comparative analysis, with an emphasis on water as the primary source of possible contamination along the food chain. Full article
(This article belongs to the Special Issue Spectroscopy-Based Biosensors)
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15 pages, 1526 KiB  
Article
The Presence of Polysaccharides, Glycerol, and Polyethyleneimine in Hydrogel Enhances the Performance of the Glucose Biosensor
by Marco Fois, Paola Arrigo, Andrea Bacciu, Patrizia Monti, Salvatore Marceddu, Gaia Rocchitta and Pier Andrea Serra
Biosensors 2019, 9(3), 95; https://doi.org/10.3390/bios9030095 - 30 Jul 2019
Cited by 7 | Viewed by 6358
Abstract
The use of amperometric biosensors has attracted particular attention in recent years, both from researchers and from companies, as they have proven to be low-cost, reliable, and very sensitive devices, with a wide range of uses in different matrices. The continuous development of [...] Read more.
The use of amperometric biosensors has attracted particular attention in recent years, both from researchers and from companies, as they have proven to be low-cost, reliable, and very sensitive devices, with a wide range of uses in different matrices. The continuous development of amperometric biosensors, since their use involves an enzyme, is specifically aimed at keeping and increasing the catalytic properties of the loaded protein, so as to be able to use the same device over time. The present study aimed to investigate the impact of glycerol and polysaccharides, in the presence of polycationic substances to constitute a hydrogel, in enhancing the enzymatic and analytic performance of a glucose biosensor. Initially, it was possible to verify how the deposition of the starch-based hydrogel, in addition to allowing the electropolymerization of the poly(p-phenylenediamine) polymer and the maintenance of its ability to shield the ascorbic acid, did not substantially limit the permeability towards hydrogen peroxide. Moreover, different biosensor designs, loading a mixture containing all the components (alone or in combination) and the enzyme, were tested in order to evaluate the changes of the apparent enzyme kinetic parameters, such as VMAX and KM, and analytical response in terms of Linear Region Slope, highlighting how the presence of all components (starch, glycerol, and polyethyleneimine) were able to substantially enhance the performance of the biosensors. The surface analysis of the biosensors was performed by scanning electron microscope (SEM). More, it was shown that the same performances were kept unchanged for seven days, proving the suitability of this biosensor design for short- and mid-term use. Full article
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15 pages, 1800 KiB  
Article
Detection of Salmonella Typhimurium in Romaine Lettuce Using a Surface Plasmon Resonance Biosensor
by Devendra Bhandari, Fur-Chi Chen and Roger C. Bridgman
Biosensors 2019, 9(3), 94; https://doi.org/10.3390/bios9030094 - 28 Jul 2019
Cited by 38 | Viewed by 7982
Abstract
Leafy vegetables have been associated with high-profile outbreaks causing severe illnesses. Timely and accurate identification of potential contamination is essential to ensure food safety. A surface plasmon resonance (SPR) assay has been developed for the detection of Salmonella Typhimurium in leafy vegetables. The [...] Read more.
Leafy vegetables have been associated with high-profile outbreaks causing severe illnesses. Timely and accurate identification of potential contamination is essential to ensure food safety. A surface plasmon resonance (SPR) assay has been developed for the detection of Salmonella Typhimurium in leafy vegetables. The assay utilizes a pair of well characterized monoclonal antibodies specific to the flagellin of S. Typhimurium. Samples of romaine lettuce contaminated with S. Typhimurium at different levels (between 0.9 and 5.9 log cfu/g) were pre-enriched in buffered peptone water. Three SPR assay formats, direct assay, sequential two-step sandwich assay, and pre-incubation one-step sandwich assay were evaluated. All three assay formats detect well even at a low level of contamination (0.9 log cfu/g). The SPR assay showed a high specificity for the detection of S. Typhimurium in the presence of other commensal bacteria in the romaine lettuce samples. The results also suggested that further purification of flagellin from the sample preparation using immunomagnetic separation did not improve the detection sensitivity of the SPR assay. The functional protocol developed in this study can be readily used for the detection of S. Typhimurium in leafy vegetables with high sensitivity and specificity. Full article
(This article belongs to the Special Issue Biosensors Applications for the Detection of Food Contaminants and Adulterants)
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9 pages, 2889 KiB  
Article
Preparation and Characterization of Perforated SERS Active Array for Particle Trapping and Sensitive Molecular Analysis
by István Rigó, Miklós Veres, Tamás Váczi, Eszter Holczer, Orsolya Hakkel, András Deák and Péter Fürjes
Biosensors 2019, 9(3), 93; https://doi.org/10.3390/bios9030093 - 25 Jul 2019
Cited by 8 | Viewed by 5557
Abstract
A gold-coated array of flow-through inverse pyramids applicable as substrate for entrapment and immobilization of micro-objects and for surface enhanced Raman spectroscopic measurements was fabricated using bulk micromachining techniques from silicon. Surface morphology, optical reflectance, immobilization properties, and surface enhanced Raman amplification of [...] Read more.
A gold-coated array of flow-through inverse pyramids applicable as substrate for entrapment and immobilization of micro-objects and for surface enhanced Raman spectroscopic measurements was fabricated using bulk micromachining techniques from silicon. Surface morphology, optical reflectance, immobilization properties, and surface enhanced Raman amplification of the array were modelled and characterized. It was found that the special perforated periodic 3D structure can be used for parallel particle and cell trapping and highly sensitive molecular analysis of the immobilized objects. Full article
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18 pages, 1584 KiB  
Review
Microbial Fuel Cell-Based Biosensors
by Yang Cui, Bin Lai and Xinhua Tang
Biosensors 2019, 9(3), 92; https://doi.org/10.3390/bios9030092 - 23 Jul 2019
Cited by 115 | Viewed by 13161
Abstract
The microbial fuel cell (MFC) is a promising environmental biotechnology that has been proposed mainly for power production and wastewater treatment. Though small power output constrains its application for directly operating most electrical devices, great progress in its chemical, electrochemical, and microbiological aspects [...] Read more.
The microbial fuel cell (MFC) is a promising environmental biotechnology that has been proposed mainly for power production and wastewater treatment. Though small power output constrains its application for directly operating most electrical devices, great progress in its chemical, electrochemical, and microbiological aspects has expanded the applications of MFCs into other areas such as the generation of chemicals (e.g., formate or methane), bioremediation of contaminated soils, water desalination, and biosensors. In recent decades, MFC-based biosensors have drawn increasing attention because of their simplicity and sustainability, with applications ranging from the monitoring of water quality (e.g., biochemical oxygen demand (BOD), toxicants) to the detection of air quality (e.g., carbon monoxide, formaldehyde). In this review, we summarize the status quo of MFC-based biosensors, putting emphasis on BOD and toxicity detection. Furthermore, this review covers other applications of MFC-based biosensors, such as DO and microbial activity. Further, challenges and prospects of MFC-based biosensors are briefly discussed. Full article
(This article belongs to the Special Issue Dedication to TUT President Isao Karube: Microbial Biosensors)
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12 pages, 1533 KiB  
Article
Application of Aluminum Hydroxide for Improvement of Label-Free SERS Detection of Some Cephalosporin Antibiotics in Urine
by Natalia E. Markina and Alexey V. Markin
Biosensors 2019, 9(3), 91; https://doi.org/10.3390/bios9030091 - 23 Jul 2019
Cited by 23 | Viewed by 6314
Abstract
This report is dedicated to development of surface-enhanced Raman spectroscopy (SERS) based analysis protocol for detection of antibiotics in urine. The key step of the protocol is the pretreatment of urine before the detection to minimize background signal. The pretreatment includes extraction of [...] Read more.
This report is dedicated to development of surface-enhanced Raman spectroscopy (SERS) based analysis protocol for detection of antibiotics in urine. The key step of the protocol is the pretreatment of urine before the detection to minimize background signal. The pretreatment includes extraction of intrinsic urine components using aluminum hydroxide gel (AHG) and further pH adjusting of the purified sample. The protocol was tested by detection of a single antibiotic in artificially spiked samples of real urine. Five antibiotics of cephalosporin class (cefazolin, cefoperazone, cefotaxime, ceftriaxone, and cefuroxime) were used for testing. SERS measurements were performed using a portable Raman spectrometer with 638 nm excitation wavelength and silver nanoparticles as SERS substrate. The calibration curves of four antibiotics (cefuroxime is the exception) cover the concentrations required for detection in patient’s urine during therapy (25/100‒500 μg/mL). Random error of the analysis (RSD < 20%) and limits of quantification (20‒90 μg/mL) for these antibiotics demonstrate the applicability of the protocol for reliable quantitative detection during therapeutic drug monitoring. The detection of cefuroxime using the protocol is not sensitive enough, allowing only for qualitative detection. Additionally, time stability and batch-to-batch reproducibility of AHG were studied and negative influence of the pretreatment protocol and its limitations were estimated and discussed. Full article
(This article belongs to the Special Issue SERS-Spectroscopy for Biosensing)
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14 pages, 2544 KiB  
Article
Design and Evaluation of a Non-Contact Bed-Mounted Sensing Device for Automated In-Home Detection of Obstructive Sleep Apnea: A Pilot Study
by Clara Mosquera-Lopez, Joseph Leitschuh, John Condon, Chad C. Hagen, Uma Rajhbeharrysingh, Cody Hanks and Peter G. Jacobs
Biosensors 2019, 9(3), 90; https://doi.org/10.3390/bios9030090 - 22 Jul 2019
Cited by 12 | Viewed by 6482
Abstract
We conducted a pilot study to evaluate the accuracy of a custom built non-contact pressure-sensitive device in diagnosing obstructive sleep apnea (OSA) severity as an alternative to in-laboratory polysomnography (PSG) and a Type 3 in-home sleep apnea test (HSAT). Fourteen patients completed PSG [...] Read more.
We conducted a pilot study to evaluate the accuracy of a custom built non-contact pressure-sensitive device in diagnosing obstructive sleep apnea (OSA) severity as an alternative to in-laboratory polysomnography (PSG) and a Type 3 in-home sleep apnea test (HSAT). Fourteen patients completed PSG sleep studies for one night with simultaneous recording from our load-cell-based sensing device in the bed. Subjects subsequently installed pressure sensors in their bed at home and recorded signals for up to four nights. Machine learning models were optimized to classify sleep apnea severity using a standardized American Academy of Sleep Medicine (AASM) scoring of the gold standard studies as reference. On a per-night basis, our model reached a correct OSA detection rate of 82.9% (sensitivity = 88.9%, specificity = 76.5%), and OSA severity classification accuracy of 74.3% (61.5% and 81.8% correctly classified in-clinic and in-home tests, respectively). There was no difference in Apnea Hypopnea Index (AHI) estimation when subjects wore HSAT sensors versus load cells (LCs) only (p-value = 0.62). Our in-home diagnostic system provides an unobtrusive method for detecting OSA with high sensitivity and may potentially be used for long-term monitoring of breathing during sleep. Further research is needed to address the lower specificity resulting from using the highest AHI from repeated samples. Full article
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16 pages, 1741 KiB  
Review
Towards Lateral Flow Quantitative Assays: Detection Approaches
by Alexandr E. Urusov, Anatoly V. Zherdev and Boris B. Dzantiev
Biosensors 2019, 9(3), 89; https://doi.org/10.3390/bios9030089 - 17 Jul 2019
Cited by 141 | Viewed by 19202
Abstract
Point-of-care (POC) or bedside analysis is a global trend in modern diagnostics. Progress in POC testing has largely been provided by advanced manufacturing technology for lateral flow (immunochromatographic) test strips. They are widely used to rapidly and easily control a variety of biomarkers [...] Read more.
Point-of-care (POC) or bedside analysis is a global trend in modern diagnostics. Progress in POC testing has largely been provided by advanced manufacturing technology for lateral flow (immunochromatographic) test strips. They are widely used to rapidly and easily control a variety of biomarkers of infectious diseases and metabolic and functional disorders, as well as in consumer protection and environmental monitoring. However, traditional lateral flow tests rely on visual assessment and qualitative conclusion, which limit the objectivity and information output of the assays. Therefore, there is a need for approaches that retain the advantages of lateral flow assays and provide reliable quantitative information about the content of a target compound in a sample mixture. This review describes the main options for detecting, processing, and interpreting immunochromatographic analysis results. The possibilities of modern portable detectors that register colored, fluorescent, magnetic, and conductive labels are discussed. Prospects for further development in this direction are also examined. Full article
(This article belongs to the Special Issue Optical Diagnostics with Point-of-Care and Point-of-Need Applications)
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14 pages, 1964 KiB  
Article
Diazonium-Modified Screen-Printed Electrodes for Immunosensing Growth Hormone in Blood Samples
by Nan Li, Ari M. Chow, Hashwin V. S. Ganesh, Melanie Ratnam, Ian R. Brown and Kagan Kerman
Biosensors 2019, 9(3), 88; https://doi.org/10.3390/bios9030088 - 17 Jul 2019
Cited by 12 | Viewed by 6506
Abstract
Altered growth hormone (GH) levels represent a major global health challenge that would benefit from advances in screening methods that are rapid and low cost. Here, we present a miniaturized immunosensor using disposable screen-printed carbon electrodes (SPCEs) for the detection of GH with [...] Read more.
Altered growth hormone (GH) levels represent a major global health challenge that would benefit from advances in screening methods that are rapid and low cost. Here, we present a miniaturized immunosensor using disposable screen-printed carbon electrodes (SPCEs) for the detection of GH with high sensitivity. The diazonium-based linker layer was electrochemically deposited onto SPCE surfaces, and subsequently activated using covalent agents to immobilize monoclonal anti-GH antibodies as the sensing layer. The surface modifications were monitored using contact angle measurements and X-ray photoelectron spectroscopy (XPS). The dissociation constant, Kd, of the anti-GH antibodies was also determined as 1.44 (±0.15) using surface plasmon resonance (SPR). The immunosensor was able to detect GH in the picomolar range using a 20 µL sample volume in connection with electrochemical impedance spectroscopy (EIS). The selectivity of the SPCE-based immunosensors was also challenged with whole blood and serum samples collected at various development stages of rats, demonstrating the potential applicability for detection in biological samples. Our results demonstrated that SPCEs provided the development of low-cost and single-use electrochemical immunosensors in comparison with glassy carbon electrode (GCE)-based ones. Full article
(This article belongs to the Special Issue Dedication to Professor Agustín Costa-García: Screen-Printed Electrodes-Based (Bio)sensors: Development and New Challenges of the 21st Century)
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13 pages, 6044 KiB  
Article
Reflectance-Based Organic Pulse Meter Sensor for Wireless Monitoring of Photoplethysmogram Signal
by Fahed Elsamnah, Anubha Bilgaiyan, Muhamad Affiq, Chang-Hoon Shim, Hiroshi Ishidai and Reiji Hattori
Biosensors 2019, 9(3), 87; https://doi.org/10.3390/bios9030087 - 10 Jul 2019
Cited by 25 | Viewed by 14173
Abstract
This paper compares the structural design of two organic biosensors that minimize power consumption in wireless photoplethysmogram (PPG) waveform monitoring. Both devices were fabricated on the same substrate with a red organic light-emitting diode (OLED) and an organic photodiode (OPD). Both were designed [...] Read more.
This paper compares the structural design of two organic biosensors that minimize power consumption in wireless photoplethysmogram (PPG) waveform monitoring. Both devices were fabricated on the same substrate with a red organic light-emitting diode (OLED) and an organic photodiode (OPD). Both were designed with a circular OLED at the center of the device surrounded by OPD. One device had an OLED area of 0.06 cm2, while the other device had half the area. The gap distance between the OLED and OPD was 1.65 mm for the first device and 2 mm for the second. Both devices had an OPD area of 0.16 cm2. We compared the power consumption and signal-to-noise ratio (SNR) of both devices and evaluated the PPG signal, which was successfully collected from a fingertip. The reflectance-based organic pulse meter operated successfully and at a low power consumption of 8 µW at 18 dB SNR. The device sent the PPG waveforms, via Bluetooth low energy (BLE), to a PC host at a maximum rate of 256 kbps data throughput. In the end, the proposed reflectance-based organic pulse meter reduced power consumption and improved long-term PPG wireless monitoring. Full article
(This article belongs to the Special Issue Bioelectric Sensors)
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19 pages, 1737 KiB  
Review
The Role of Electrochemical Immunosensors in Clinical Analysis
by Fariba Mollarasouli, Sevinc Kurbanoglu and Sibel A. Ozkan
Biosensors 2019, 9(3), 86; https://doi.org/10.3390/bios9030086 - 9 Jul 2019
Cited by 186 | Viewed by 14654
Abstract
An immunosensor is a kind of affinity biosensor based on interactions between an antigen and specific antigen immobilized on a transducer surface. Immunosensors possess high selectivity and sensitivity due to the specific binding between antibody and corresponding antigen, making them a suitable platform [...] Read more.
An immunosensor is a kind of affinity biosensor based on interactions between an antigen and specific antigen immobilized on a transducer surface. Immunosensors possess high selectivity and sensitivity due to the specific binding between antibody and corresponding antigen, making them a suitable platform for several applications especially in the medical and bioanalysis fields. Electrochemical immunosensors rely on the measurements of an electrical signal recorded by an electrochemical transducer and can be classed as amperometric, potentiometric, conductometric, or impedimetric depending on the signal type. Among the immunosensors, electrochemical immunosensors have been more perfected due to their simplicity and, especially their ability to be portable, and for in situ or automated detection. This review addresses the potential of immunosensors destined for application in clinical analysis, especially cancer biomarker diagnosis. The emphasis is on the approaches used to fabricate electrochemical immunosensors. A general overview of recent applications of the developed electrochemical immunosensors in the clinical approach is described. Full article
(This article belongs to the Special Issue Electrochemical Immunosensor)
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14 pages, 2054 KiB  
Article
Cyclic Olefin Copolymer Microfluidic Devices for Forensic Applications
by Brigitte Bruijns, Andrea Veciana, Roald Tiggelaar and Han Gardeniers
Biosensors 2019, 9(3), 85; https://doi.org/10.3390/bios9030085 - 4 Jul 2019
Cited by 37 | Viewed by 7788
Abstract
Microfluidic devices offer important benefits for forensic applications, in particular for fast tests at a crime scene. A large portion of forensic applications require microfluidic chip material to show compatibility with biochemical reactions (such as amplification reactions), and to have high transparency in [...] Read more.
Microfluidic devices offer important benefits for forensic applications, in particular for fast tests at a crime scene. A large portion of forensic applications require microfluidic chip material to show compatibility with biochemical reactions (such as amplification reactions), and to have high transparency in the visible region and high chemical resistance. Also, preferably, manufacturing should be simple. The characteristic properties of cyclic olefin copolymer (COC) fulfills these requirements and offers new opportunities for the development of new forensic tests. In this work, the versatility of COC as material for lab-on-a-chip (LOC) systems in forensic applications has been explored by realizing two proof-of-principle devices. Chemical resistance and optical transparency were investigated for the development of an on-chip presumptive color test to indicate the presence of an illicit substance through applying absorption spectroscopy. Furthermore, the compatibility of COC with a DNA amplification reaction was verified by performing an on-chip multiple displacement amplification (MDA) reaction. Full article
(This article belongs to the Special Issue Advances in Lab-on-Chip Devices II)
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12 pages, 4350 KiB  
Article
Development of a Label-Free Electrochemical Aptasensor for the Detection of Tau381 and its Preliminary Application in AD and Non-AD Patients’ Sera
by Dan Tao, Bingqing Shui, Yingying Gu, Jing Cheng, Weiying Zhang, Nicole Jaffrezic-Renault, Shizhen Song and Zhenzhong Guo
Biosensors 2019, 9(3), 84; https://doi.org/10.3390/bios9030084 - 30 Jun 2019
Cited by 56 | Viewed by 8140
Abstract
The electrochemical aptamer sensor has been designed for detecting tau381, a critical biomarker of Alzheimer′s disease in human serum. The aptasensor is obtained by immobilizing the aptamer on a carboxyl graphene/thionin/gold nanoparticle modified glassy-carbon electrode. As a probe and bridge molecule, thionin connected [...] Read more.
The electrochemical aptamer sensor has been designed for detecting tau381, a critical biomarker of Alzheimer′s disease in human serum. The aptasensor is obtained by immobilizing the aptamer on a carboxyl graphene/thionin/gold nanoparticle modified glassy-carbon electrode. As a probe and bridge molecule, thionin connected carboxyl graphene and gold nanoparticles, and gave the electrical signal. Under optimal conditions, the increment of differential pulse voltammetry signal increased linearly with the logarithm of tau381 concentration in the range from 1.0 pM to 100 pM, and limit of detection was 0.70 pM. The aptasensor reliability was evaluated by determining its selectivity, reproducibility, stability, detection limit, and recovery. Performance analysis of the tau381 aptasensor in 10 patients’ serum samples showed that the aptasensor could screen patients with and without Alzheimer′s disease. The proposed aptasensor has potential for use in clinically diagnosing Alzheimer′s disease in the early stage. Full article
(This article belongs to the Special Issue Electrochemical Immunosensor)
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15 pages, 3722 KiB  
Article
Plasmonic Detection of Glucose in Serum Based on Biocatalytic Shape-Altering of Gold Nanostars
by Masauso Moses Phiri, Danielle Wingrove Mulder and Barend Christiaan Vorster
Biosensors 2019, 9(3), 83; https://doi.org/10.3390/bios9030083 - 29 Jun 2019
Cited by 9 | Viewed by 6688
Abstract
Nanoparticles have been used as signal transducers for optical readouts in biosensors. Optical approaches are cost-effective with easy readout formats for clinical diagnosis. We present a glucose biosensor based on the biocatalytic shape-altering of gold nanostars via silver deposition. Improved sensitivity was observed [...] Read more.
Nanoparticles have been used as signal transducers for optical readouts in biosensors. Optical approaches are cost-effective with easy readout formats for clinical diagnosis. We present a glucose biosensor based on the biocatalytic shape-altering of gold nanostars via silver deposition. Improved sensitivity was observed due to the nanostars clustering after being functionalised with glucose oxidase (GOx). The biosensor quantified glucose in the serum samples with a 1:1000 dilution factor, and colorimetrically distinguished between the concentrations. The assay demonstrated good specificity and sensitivity. The fabricated glucose biosensor is a rapid kinetic assay using a basic entry level laboratory spectrophotometric microplate reader. Such a biosensor could be very useful in resource-constrained regions without state-of-the-art laboratory equipment. Furthermore, naked eye detection of glucose makes this a suitable biosensor for technology transfer to other point-of-care devices. Full article
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11 pages, 2317 KiB  
Article
EMG-Based Characterization of Walking Asymmetry in Children with Mild Hemiplegic Cerebral Palsy
by Francesco Di Nardo, Annachiara Strazza, Alessandro Mengarelli, Stefano Cardarelli, Andrea Tigrini, Federica Verdini, Alberto Nascimbeni, Valentina Agostini, Marco Knaflitz and Sandro Fioretti
Biosensors 2019, 9(3), 82; https://doi.org/10.3390/bios9030082 - 27 Jun 2019
Cited by 24 | Viewed by 6498
Abstract
Hemiplegia is a neurological disorder that is often detected in children with cerebral palsy. Although many studies have investigated muscular activity in hemiplegic legs, few EMG-based findings focused on unaffected limb. This study aimed to quantify the asymmetric behavior of lower-limb-muscle recruitment during [...] Read more.
Hemiplegia is a neurological disorder that is often detected in children with cerebral palsy. Although many studies have investigated muscular activity in hemiplegic legs, few EMG-based findings focused on unaffected limb. This study aimed to quantify the asymmetric behavior of lower-limb-muscle recruitment during walking in mild-hemiplegic children from surface-EMG and foot-floor contact features. sEMG signals from tibialis anterior (TA) and gastrocnemius lateralis and foot-floor contact data during walking were analyzed in 16 hemiplegic children classified as W1 according to Winter’ scale, and in 100 control children. Statistical gait analysis, a methodology achieving a statistical characterization of gait by averaging surface-EMG-based features, was performed. Results, achieved in hundreds of strides for each child, indicated that in the hemiplegic side with respect to the non-hemiplegic side, W1 children showed a statistically significant: decreased number of strides with normal foot-floor contact; decreased stance-phase length and initial-contact sub-phase; curtailed, less frequent TA activity in terminal swing and a lack of TA activity at heel-strike. The acknowledged impairment of anti-phase eccentric control of dorsiflexors was confirmed in the hemiplegic side, but not in the contralateral side. However, a modified foot-floor contact pattern is evinced also in the contralateral side, probably to make up for balance requirements. Full article
(This article belongs to the Special Issue Biomedical Signal Processing for the Diagnosis and Monitoring of Motor Disorders)
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