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Biosensors, Volume 11, Issue 3 (March 2021) – 37 articles

Cover Story (view full-size image): High-yield protein production of the Aryl hydrocarbon Receptor (AhR) by bacterial expression occurs in the presence of the AhR Nuclear Translocator (ARNT). Protein complexes are purified by a combination of affinity and size exclusion chromatography (Fast Protein Liquid Chromatography, FPLC). For Microscale Thermophoresis (MST) measurements, a serial dilution of non-fluorescent ligand is titrated to purified AhR–ARNT complexes and loaded on MST capillaries. Upon laser exposure, thermophoresis- and temperature-induced changes in the intrinsic fluorescence of the protein complex (AhR–ARNT) are determined, and ligand-binding constants are calculated. View this paper.
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16 pages, 2905 KiB  
Article
Multi-Layer Reflectivity Calculation Based Meta-Modeling of the Phase Mapping Function for Highly Reproducible Surface Plasmon Resonance Biosensing
by Tzu-Heng Wu, Ching-Hsu Yang, Chia-Chen Chang, Hui-Wen Liu, Chia-Yu Yang, Tang-Long Shen, Chii-Wann Lin and Aurélien Bruyant
Biosensors 2021, 11(3), 95; https://doi.org/10.3390/bios11030095 - 23 Mar 2021
Cited by 3 | Viewed by 2902
Abstract
Phase-sensitive surface plasmon resonance biosensors are known for their high sensitivity. One of the technology bottle-necks of such sensors is that the phase sensorgram, when measured at fixed angle set-up, can lead to low reproducibility as the signal conveys multiple data. Leveraging the [...] Read more.
Phase-sensitive surface plasmon resonance biosensors are known for their high sensitivity. One of the technology bottle-necks of such sensors is that the phase sensorgram, when measured at fixed angle set-up, can lead to low reproducibility as the signal conveys multiple data. Leveraging the sensitivity, while securing satisfying reproducibility, is therefore is an underdiscussed key issue. One potential solution is to map the phase sensorgram into refractive index unit by the use of sensor calibration data, via a simple non-linear fit. However, basic fitting functions poorly portray the asymmetric phase curve. On the other hand, multi-layer reflectivity calculation based on the Fresnel coefficient can be employed for a precise mapping function. This numerical approach however lacks the explicit mathematical formulation to be used in an optimization process. To this end, we aim to provide a first methodology for the issue, where mapping functions are constructed from Bayesian optimized multi-layer model of the experimental data. The challenge of using multi-layer model as optimization trial function is addressed by meta-modeling via segmented polynomial approximation. A visualization approach is proposed for assessment of the goodness-of-the-fit on the optimized model. Using metastatic cancer exosome sensing, we demonstrate how the present work paves the way toward better plasmonic sensors. Full article
(This article belongs to the Special Issue Emerging Nanoplasmonic Technologies in Biosensors)
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42 pages, 6599 KiB  
Review
Electrochemical Biosensors for Cytokine Profiling: Recent Advancements and Possibilities in the Near Future
by Nirmita Dutta, Peter B. Lillehoj, Pedro Estrela and Gorachand Dutta
Biosensors 2021, 11(3), 94; https://doi.org/10.3390/bios11030094 - 23 Mar 2021
Cited by 24 | Viewed by 5074
Abstract
Cytokines are soluble proteins secreted by immune cells that act as molecular messengers relaying instructions and mediating various functions performed by the cellular counterparts of the immune system, by means of a synchronized cascade of signaling pathways. Aberrant expression of cytokines can be [...] Read more.
Cytokines are soluble proteins secreted by immune cells that act as molecular messengers relaying instructions and mediating various functions performed by the cellular counterparts of the immune system, by means of a synchronized cascade of signaling pathways. Aberrant expression of cytokines can be indicative of anomalous behavior of the immunoregulatory system, as seen in various illnesses and conditions, such as cancer, autoimmunity, neurodegeneration and other physiological disorders. Cancer and autoimmune diseases are particularly adept at developing mechanisms to escape and modulate the immune system checkpoints, reflected by an altered cytokine profile. Cytokine profiling can provide valuable information for diagnosing such diseases and monitoring their progression, as well as assessing the efficacy of immunotherapeutic regiments. Toward this goal, there has been immense interest in the development of ultrasensitive quantitative detection techniques for cytokines, which involves technologies from various scientific disciplines, such as immunology, electrochemistry, photometry, nanotechnology and electronics. This review focusses on one aspect of this collective effort: electrochemical biosensors. Among the various types of biosensors available, electrochemical biosensors are one of the most reliable, user-friendly, easy to manufacture, cost-effective and versatile technologies that can yield results within a short period of time, making it extremely promising for routine clinical testing. Full article
(This article belongs to the Special Issue Biosensors for Rapid Diagnostics)
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22 pages, 3215 KiB  
Article
Market Perspectives and Future Fields of Application of Odor Detection Biosensors within the Biological Transformation—A Systematic Analysis
by Johannes Full, Yannick Baumgarten, Lukas Delbrück, Alexander Sauer and Robert Miehe
Biosensors 2021, 11(3), 93; https://doi.org/10.3390/bios11030093 - 23 Mar 2021
Cited by 12 | Viewed by 3747
Abstract
The technological advantages that biosensors have over conventional technical sensors for odor detection and the role they play in the biological transformation have not yet been comprehensively analyzed. However, this is necessary for assessing their suitability for specific fields of application as well [...] Read more.
The technological advantages that biosensors have over conventional technical sensors for odor detection and the role they play in the biological transformation have not yet been comprehensively analyzed. However, this is necessary for assessing their suitability for specific fields of application as well as their improvement and development goals. An overview of biological basics of olfactory systems is given and different odor sensor technologies are described and classified in this paper. Specific market potentials of biosensors for odor detection are identified by applying a tailored methodology that enables the derivation and systematic comparison of both the performance profiles of biosensors as well as the requirement profiles for various application fields. Therefore, the fulfillment of defined requirements is evaluated for biosensors by means of 16 selected technical criteria in order to determine a specific performance profile. Further, a selection of application fields, namely healthcare, food industry, agriculture, cosmetics, safety applications, environmental monitoring for odor detection sensors is derived to compare the importance of the criteria for each of the fields, leading to market-specific requirement profiles. The analysis reveals that the requirement criteria considered to be the most important ones across all application fields are high specificity, high selectivity, high repeat accuracy, high resolution, high accuracy, and high sensitivity. All these criteria, except for the repeat accuracy, can potentially be better met by biosensors than by technical sensors, according to the results obtained. Therefore, biosensor technology in general has a high application potential for all the areas of application under consideration. Health and safety applications especially are considered to have high potential for biosensors due to their correspondence between requirement and performance profiles. Special attention is paid to new areas of application that require multi-sensing capability. Application scenarios for multi-sensing biosensors are therefore derived. Moreover, the role of biosensors within the biological transformation is discussed. Full article
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11 pages, 2337 KiB  
Article
A Cationic Surfactant-Decorated Liquid Crystal-Based Aptasensor for Label-Free Detection of Malathion Pesticides in Environmental Samples
by Duy Khiem Nguyen and Chang-Hyun Jang
Biosensors 2021, 11(3), 92; https://doi.org/10.3390/bios11030092 - 23 Mar 2021
Cited by 31 | Viewed by 3427
Abstract
We report a liquid crystal (LC)-based aptasensor for the detection of malathion using a cationic surfactant-decorated LC interface. In this method, LCs displayed dark optical images when in contact with aqueous cetyltrimethylammonium bromide (CTAB) solution due to the formation of a self-assembled CTAB [...] Read more.
We report a liquid crystal (LC)-based aptasensor for the detection of malathion using a cationic surfactant-decorated LC interface. In this method, LCs displayed dark optical images when in contact with aqueous cetyltrimethylammonium bromide (CTAB) solution due to the formation of a self-assembled CTAB monolayer at the aqueous/LC interface, which induced the homeotropic orientation of LCs. With the addition of malathion aptamer, the homeotropic orientation of LCs changed to a planar one due to the interactions between CTAB and the aptamer, resulting in a bright optical image. In the presence of malathion, the formation of aptamer-malathion complexes caused a conformational change of the aptamers, thereby weakening the interactions between CTAB and the aptamers. Therefore, CTAB is free to induce a homeotropic ordering of the LCs, which corresponds to a dark optical image. The developed sensor exhibited high specificity for malathion determination and a low detection limit of 0.465 nM was achieved. Moreover, the proposed biosensor was successfully applied to detect malathion in tap water, river water, and apple samples. The proposed LC-based aptasensor is a simple, rapid, and convenient platform for label-free monitoring of malathion in environmental samples. Full article
(This article belongs to the Special Issue Portable Technologies toward ASSURED Biosensing and Diagnostics)
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14 pages, 2393 KiB  
Article
Enzymatic Electroanalytical Biosensor Based on Maramiellus colocasiae Fungus for Detection of Phytomarkers in Infusions and Green Tea Kombucha
by Érica A. Batista, Giovanna N. M. Silva, Livia F. Sgobbi, Fabio B. Machado, Isaac Y. Macedo, Emily K. Moreno, Jerônimo R. Neto, Paulo S. Scalize and Eric S. Gil
Biosensors 2021, 11(3), 91; https://doi.org/10.3390/bios11030091 - 22 Mar 2021
Cited by 5 | Viewed by 2444
Abstract
In this work, we developed an enzymatic voltammetric biosensor for the determination of catechin and gallic acid in green tea and kombucha samples. The differential pulse voltammetry (DPV) methodology was optimized regarding the amount of crude enzyme extract, incubation time in the presence [...] Read more.
In this work, we developed an enzymatic voltammetric biosensor for the determination of catechin and gallic acid in green tea and kombucha samples. The differential pulse voltammetry (DPV) methodology was optimized regarding the amount of crude enzyme extract, incubation time in the presence of the substrates, optimal pH, reuse of the biosensor, and storage time. Samples of green tea and kombucha were purchased in local markets in the city of Goiânia-GO, Brazil. High performance liquid chromatography (HPLC) and Folin-Ciocalteu spectrophotometric techniques were performed for the comparison of the analytical methods employed. In addition, two calibration curves were made, one for catechin with a linear range from 1 to 60 µM (I = −0.152 * (catechin) − 1.846), with a detection limit of 0.12 µM and a quantification limit of 0.38 µM and one for gallic acid with a linear range from 3 to 60 µM (I = −0.0415 * (gallic acid) − 0.0572), with a detection limit of 0.14 µM and a quantification limit of 0.42 µM. The proposed biosensor was efficient in the determination of phenolic compounds in green tea. Full article
(This article belongs to the Section Biosensor Materials)
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17 pages, 2220 KiB  
Article
A Simple Distance Paper-Based Analytical Device for the Screening of Lead in Food Matrices
by Kasinee Katelakha, Vanida Nopponpunth, Watcharee Boonlue and Wanida Laiwattanapaisal
Biosensors 2021, 11(3), 90; https://doi.org/10.3390/bios11030090 - 22 Mar 2021
Cited by 16 | Viewed by 3641
Abstract
A simple and rapid distance paper-based analytical device (dPAD) for the detection of lead (Pb) in foods is proposed herein. The assay principle is based on competitive binding between carminic acid (CA) and polyethyleneimine (PEI) to Pb in a food sample. The paper [...] Read more.
A simple and rapid distance paper-based analytical device (dPAD) for the detection of lead (Pb) in foods is proposed herein. The assay principle is based on competitive binding between carminic acid (CA) and polyethyleneimine (PEI) to Pb in a food sample. The paper channels were pre-immobilized with PEI, before reacting with a mixture of the sample and CA. Pb can strongly bind to the CA; hence, the length of the red color deposition on the flow channel decreased as a lower amount of free CA bound to PEI. The dPAD exhibited good linear correlation, with ranges of 5–100 µg·mL−1 (R2 = 0.974) of Pb. Although, the limit of detection (LOD) of this platform was rather high, at 12.3 µg·mL−1, a series of standard additions (8.0, 9.0, and 10.0 µg·mL−1) can be used to interpret the cutoff of Pb concentrations at higher or lower than 2 µg·mL−1. The presence of common metal ions such as calcium, magnesium, nickel, and zinc did not interfere with the color distance readout. The validity of the developed dPAD was demonstrated by its applicability to screen the contamination of Pb in century egg samples. The results obtained from the dPAD are in accordance with the concentration measured by atomic absorption spectroscopy (AAS) (n = 9). In conclusion, this proposed dPAD, combined with the standard addition method, could be applied for screening Pb contamination in food matrices. This platform is, therefore, potentially applicable for field measurements of Pb in developing countries, because it is cheap and rapid, and it requires no significant laborious instruments. Full article
(This article belongs to the Special Issue Last Advances in Optical Biosensors)
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17 pages, 2922 KiB  
Review
An Overview of Bio-Inspired Intelligent Imprinted Polymers for Virus Determination
by Shabi Abbas Zaidi
Biosensors 2021, 11(3), 89; https://doi.org/10.3390/bios11030089 - 21 Mar 2021
Cited by 25 | Viewed by 3725
Abstract
The molecular imprinting polymers (MIPs) have shown their potential in various applications including pharmaceuticals, chemical sensing and biosensing, medical diagnosis, and environmental related issues, owing to their artificial selective biomimetic recognition ability. Despite the challenges posed in the imprinting and recognition of biomacromolecules, [...] Read more.
The molecular imprinting polymers (MIPs) have shown their potential in various applications including pharmaceuticals, chemical sensing and biosensing, medical diagnosis, and environmental related issues, owing to their artificial selective biomimetic recognition ability. Despite the challenges posed in the imprinting and recognition of biomacromolecules, the use of MIP for the imprinting of large biomolecular oragnism such as viruses is of huge interest because of the necessity of early diagnosis of virus-induced diseases for clinical and point-of-care (POC) purposes. Thus, many fascinating works have been documented in which such synthetic systems undoubtedly explore a variety of potential implementations, from virus elimination, purification, and diagnosis to virus and bacteria-borne disease therapy. This study is focused comprehensively on the fabrication strategies and their usage in many virus-imprinted works that have appeared in the literature. The drawbacks, challenges, and perspectives are also highlighted. Full article
(This article belongs to the Section Biosensor Materials)
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9 pages, 2375 KiB  
Article
Specific Detection of Influenza A and B Viruses by CRISPR-Cas12a-Based Assay
by Bum Ju Park, Man Seong Park, Jae Myun Lee and Yoon Jae Song
Biosensors 2021, 11(3), 88; https://doi.org/10.3390/bios11030088 - 19 Mar 2021
Cited by 36 | Viewed by 5654
Abstract
A rapid and accurate on-site diagnostic test for pathogens including influenza viruses is critical for preventing the spread of infectious diseases. Two types of influenza virus, A and B cause seasonal flu epidemics, whereas type A can cause influenza pandemics. To specifically detect [...] Read more.
A rapid and accurate on-site diagnostic test for pathogens including influenza viruses is critical for preventing the spread of infectious diseases. Two types of influenza virus, A and B cause seasonal flu epidemics, whereas type A can cause influenza pandemics. To specifically detect influenza A (IAV) and B (IBV) viruses, we developed a clustered, regularly interspaced, short palindromic repeats (CRISPR) and CRISPR-associated (Cas) system-based assay. By coupling reverse transcription recombinase polymerase amplification (RT-RPA) and reverse transcription loop-mediated isothermal amplification (RT-LAMP), a CRISPR-Cas12a DNA endonuclease-targeted CRISPR trans-reporter (DETECTR) detected IAV and IBV titers as low as 1 × 100 plaque forming units (PFUs) per reaction without exhibiting cross-reactivity. Only 75 to 85 min were required to detect IAV and IBV, depending on isothermal nucleic acid amplification methods, and results were verified using a lateral flow strip assay that does not require additional analytic equipment. Taken together, our findings establish RT-RPA and RT-LAMP-coupled DETECTR-based diagnostic tests for rapid, specific and high-sensitivity detection of IAV and IBV using fluorescence and lateral flow assays. The diagnostic test developed in this study can be used to distinguish IAV and IBV infections, a capability that is necessary for monitoring and preventing the spread of influenza epidemics and pandemics. Full article
(This article belongs to the Special Issue Biosensors for Rapid Diagnostics)
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13 pages, 2117 KiB  
Article
Label-Free and Highly-Sensitive Detection of Ochratoxin A Using One-Pot Synthesized Reduced Graphene Oxide/Gold Nanoparticles-Based Impedimetric Aptasensor
by Yasmin Alhamoud, Yingying Li, Haibo Zhou, Ragwa Al-Wazer, Yiying Gong, Shuai Zhi and Danting Yang
Biosensors 2021, 11(3), 87; https://doi.org/10.3390/bios11030087 - 19 Mar 2021
Cited by 10 | Viewed by 3119
Abstract
Ochratoxin A (OTA) primarily obtained by the genera aspergillus and penicillium, is one of the toxic substances for different organs and systems of the human body such as the kidney, liver, neurons and the immune system. Moreover, it is considered to cause [...] Read more.
Ochratoxin A (OTA) primarily obtained by the genera aspergillus and penicillium, is one of the toxic substances for different organs and systems of the human body such as the kidney, liver, neurons and the immune system. Moreover, it is considered to cause tumors and fetal malformation even at a very low concentration. Fast and sensitive assay for detection of OTA at ultralow levels in foods and agricultural products has been an increasing demand. In this study, a new label-free electrochemical biosensor based on three-dimensional reduced graphene oxide/gold nanoparticles/aptamer for OTA detection was constructed. The 3D-rGO/Au NPs nanocomposites were firstly synthesized using a one-pot hydrothermal process under optimized experimental conditions. The 3D-rGO/Au NPs with considerable particular surface area and outstanding electrical conductivity was then coated on a glass carbon electrode to provide tremendous binding sites for -SH modified aptamer via the distinctive Au–S linkage. The presence of OTA was specifically captured by aptamer and resulted in electrochemical impedance spectroscopy (EIS) signal response accordingly. The constructed impedimetric aptasensor obtained a broad linear response from 1 pg/mL to 10 ng/mL with an LOD of 0.34 pg/mL toward OTA detection, highlighting the excellent sensitivity. Satisfactory reproducibility was also achieved with the relative standard deviation (RSD) of 1.393%. Moreover, the proposed aptasensor obtained a good recovery of OTA detection in red wine samples within the range of 93.14 to 112.75% along with a low LOD of 0.023 ng/mL, indicating its applicability for OTA detection in real samples along with economical, specific, susceptible, fast, easy, and transportable merits. Full article
(This article belongs to the Section Biosensor and Bioelectronic Devices)
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12 pages, 12529 KiB  
Article
Subtle Application of Electrical Field-Induced Lossy Mode Resonance to Enhance Performance of Optical Planar Waveguide Biosensor
by Yu-Cheng Lin and Liang-Yü Chen
Biosensors 2021, 11(3), 86; https://doi.org/10.3390/bios11030086 - 18 Mar 2021
Cited by 13 | Viewed by 3387
Abstract
Many studies concern the generation of lossy mode resonances (LMRs) using metallic oxide thin films that are deposited on optical fiber. However, the LMR-based optical fiber sensors are frangible, do not allow easy surface modification, and are not suited to mass production. This [...] Read more.
Many studies concern the generation of lossy mode resonances (LMRs) using metallic oxide thin films that are deposited on optical fiber. However, the LMR-based optical fiber sensors are frangible, do not allow easy surface modification, and are not suited to mass production. This study proposes an electrical field-induced LMR-based biosensor with an optical planar waveguide to replace surface modification and allow the mass production of protein biosensors and accelerate the speed of the analyte to decrease the detection time. Experimentally, the biosensor is evaluated using charged serum albumin molecules and characterized in terms of the LMR wavelength shift using an externally applied voltage for different durations. The externally applied voltage generates a significant electric field, which drives the non-neutralized biomolecules and increases the LMR wavelength shift. Our experimental results demonstrate that there are two different mechanisms of adsorption of serum albumin molecules for short-term and long-term observations. These are used to calculate the sensitivity of the biosensor. This electrical field-induced method is highly significant for the development and fabrication of LMR-based biosensors. Full article
(This article belongs to the Section Biosensor and Bioelectronic Devices)
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12 pages, 2624 KiB  
Article
Immobilization-Free Electrochemical Sensor Coupled with a Graphene-Oxide-Based Aptasensor for Glycated Albumin Detection
by Wassa Waiwinya, Thitirat Putnin, Dechnarong Pimalai, Wireeya Chawjiraphan, Nuankanya Sathirapongsasuti and Deanpen Japrung
Biosensors 2021, 11(3), 85; https://doi.org/10.3390/bios11030085 - 17 Mar 2021
Cited by 21 | Viewed by 3453
Abstract
An immobilization-free electrochemical sensor coupled with a graphene oxide (GO)-based aptasensor was developed for glycated human serum albumin (GHSA) detection. The concentration of GHSA was monitored by measuring the electrochemical response of free GO and aptamer-bound GO in the presence of glycated albumin; [...] Read more.
An immobilization-free electrochemical sensor coupled with a graphene oxide (GO)-based aptasensor was developed for glycated human serum albumin (GHSA) detection. The concentration of GHSA was monitored by measuring the electrochemical response of free GO and aptamer-bound GO in the presence of glycated albumin; their currents served as the analytical signals. The electrochemical aptasensor exhibited good performance with a base-10 logarithmic scale. The calibration curve was achieved in the range of 0.01–50 µg/mL. The limit of detection (LOD) was 8.70 ng/mL. The developed method was considered a one-drop measurement process because a fabrication step and the probe-immobilization process were not required. This simple sensor offers a cost-effective, rapid, and sensitive detection method, and could be an alternative approach for determination of GHSA levels. Full article
(This article belongs to the Section Biosensor and Bioelectronic Devices)
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13 pages, 10985 KiB  
Communication
3D-PAD: Paper-Based Analytical Devices with Integrated Three-Dimensional Features
by James S. Ng and Michinao Hashimoto
Biosensors 2021, 11(3), 84; https://doi.org/10.3390/bios11030084 - 17 Mar 2021
Cited by 7 | Viewed by 3382
Abstract
This paper describes the use of fused deposition modeling (FDM) printing to fabricate paper-based analytical devices (PAD) with three-dimensional (3D) features, which is termed as 3D-PAD. Material depositions followed by heat reflow is a standard approach for the fabrication of PAD. Such devices [...] Read more.
This paper describes the use of fused deposition modeling (FDM) printing to fabricate paper-based analytical devices (PAD) with three-dimensional (3D) features, which is termed as 3D-PAD. Material depositions followed by heat reflow is a standard approach for the fabrication of PAD. Such devices are primarily two-dimensional (2D) and can hold only a limited amount of liquid samples in the device. This constraint can pose problems when the sample consists of organic solvents that have low interfacial energies with the hydrophobic barriers. To overcome this limitation, we developed a method to fabricate PAD integrated with 3D features (vertical walls as an example) by FDM 3D printing. 3D-PADs were fabricated using two types of thermoplastics. One thermoplastic had a low melting point that formed hydrophobic barriers upon penetration, and another thermoplastic had a high melting point that maintained 3D features on the filter paper without reflowing. We used polycaprolactone (PCL) for the former, and polylactic acid (PLA) for the latter. Both PCL and PLA were printed with FDM without gaps at the interface, and the resulting paper-based devices possessed hydrophobic barriers consisting of PCL seamlessly integrated with vertical features consisting of PLA. We validated the capability of 3D-PAD to hold 30 μL of solvents (ethanol, isopropyl alcohol, and acetone), all of which would not be retained on conventional PADs fabricated with solid wax printers. To highlight the importance of containing an increased amount of liquid samples, a colorimetric assay for the formation of dimethylglyoxime (DMG)-Ni (II) was demonstrated using two volumes (10 μL and 30 μL) of solvent-based dimethylglyoxime (DMG). FDM printing of 3D-PAD enabled the facile construction of 3D structures integrated with PAD, which would find applications in paper-based chemical and biological assays requiring organic solvents. Full article
(This article belongs to the Collection Recent Developments in Microfluidics)
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13 pages, 628 KiB  
Article
Study of Two Constraints Impacting Measurements of Human Glycemia Using a Microwave Sensor
by Mohamed Amine Zidane, Hichem Amar and Amar Rouane
Biosensors 2021, 11(3), 83; https://doi.org/10.3390/bios11030083 - 15 Mar 2021
Cited by 4 | Viewed by 3082
Abstract
The measurement of glycemia is impacted by several constraints; those constraints have to be identified and quantified when designing an electromagnetic noninvasive sensor. The second phase concerns the level of the influence of these constraints. In this work, we investigated the impact of [...] Read more.
The measurement of glycemia is impacted by several constraints; those constraints have to be identified and quantified when designing an electromagnetic noninvasive sensor. The second phase concerns the level of the influence of these constraints. In this work, we investigated the impact of vein radius located in the forearm on a resonant microwave sensor to measure glycemia. We performed a numerical simulation using COMSOL Multiphysics of a proposed tissue model that was in contact with a microwave resonator. Some other factors affect the measurement, such as temperature, perfusion, sensor positioning and motion, tissue heterogeneity, and other biological activity. The sensor must be robust to the above-mentioned constraints. Because vein size changes from one person to another, the dielectric properties seen by the sensor will be different. This has been demonstrated by the change created in the resonance frequency of the simulated sensor for different vein sizes. The second constraint that was assessed is the dosimetry. The specific absorption rate (SAR) of any electromagnetic device should be evaluated and compared with SAR limits in the safety standards to ensure the safety of the user. Simulation results are in good agreement with SAR limits in the safety standards. Full article
(This article belongs to the Section Biosensor and Bioelectronic Devices)
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21 pages, 1365 KiB  
Review
Biosensors for Biogenic Amines: A Review
by Helena Vasconcelos, Luís C. C. Coelho, Ana Matias, Cristina Saraiva, Pedro A. S. Jorge and José M. M. M. de Almeida
Biosensors 2021, 11(3), 82; https://doi.org/10.3390/bios11030082 - 13 Mar 2021
Cited by 34 | Viewed by 4870
Abstract
Biogenic amines (BAs) are well-known biomolecules, mostly for their toxic and carcinogenic effects. Commonly, they are used as an indicator of quality preservation in food and beverages since their presence in higher concentrations is associated with poor quality. With respect to BA’s metabolic [...] Read more.
Biogenic amines (BAs) are well-known biomolecules, mostly for their toxic and carcinogenic effects. Commonly, they are used as an indicator of quality preservation in food and beverages since their presence in higher concentrations is associated with poor quality. With respect to BA’s metabolic pathways, time plays a crucial factor in their formation. They are mainly formed by microbial decarboxylation of amino acids, which is closely related to food deterioration, therefore, making them unfit for human consumption. Pathogenic microorganisms grow in food without any noticeable change in odor, appearance, or taste, thus, they can reach toxic concentrations. The present review provides an overview of the most recent literature on BAs with special emphasis on food matrixes, including a description of the typical BA assay formats, along with its general structure, according to the biorecognition elements used (enzymes, nucleic acids, whole cells, and antibodies). The extensive and significant amount of research that has been done to the investigation of biorecognition elements, transducers, and their integration in biosensors, over the years has been reviewed. Full article
(This article belongs to the Special Issue Biosensors for the Detection of Nitrogen-Based Compounds)
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15 pages, 3809 KiB  
Article
Signal Amplification in an Optical and Dielectric Biosensor Employing Liquid Crystal-Photopolymer Composite as the Sensing Medium
by Hassanein Shaban, Shih-Chun Yen, Mon-Juan Lee and Wei Lee
Biosensors 2021, 11(3), 81; https://doi.org/10.3390/bios11030081 - 13 Mar 2021
Cited by 10 | Viewed by 2463
Abstract
An optical and dielectric biosensor based on a liquid crystal (LC)–photopolymer composite was established in this study for the detection and quantitation of bovine serum albumin (BSA). When the nematic LC E7 was doped with 4-wt.% NOA65, a photo-curable prepolymer, and photopolymerized by [...] Read more.
An optical and dielectric biosensor based on a liquid crystal (LC)–photopolymer composite was established in this study for the detection and quantitation of bovine serum albumin (BSA). When the nematic LC E7 was doped with 4-wt.% NOA65, a photo-curable prepolymer, and photopolymerized by UV irradiation at 20 mW/cm2 for 300 s, the limit of detection determined by image analysis of the LC optical texture and dielectric spectroscopic measurements was 3400 and 88 pg/mL for BSA, respectively, which were lower than those detected with E7 alone (10 μg/mL BSA). The photopolymerized NOA65, but not the prepolymer prior to UV exposure, contributed to the enhanced optical signal, and UV irradiation of pristine E7 in the absence of NOA65 had no effect on the optical texture. The effective tilt angle θ, calculated from the real-part dielectric constant ε’, decreased with increasing BSA concentration, providing strong evidence for the correlation of photopolymerized NOA65 to the intensified disruption in the vertically oriented LC molecules to enhance the optical and dielectric signals of BSA. The optical and dielectric anisotropy of LCs and the photo-curable dopant facilitate novel quantitative and signal amplification approaches to potential development of LC-based biosensors. Full article
(This article belongs to the Special Issue Electrical and Electro-Optical Biosensors)
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12 pages, 1998 KiB  
Communication
Microfluidic Impedance Biosensor Chips Using Sensing Layers Based on DNA-Based Self-Assembled Monolayers for Label-Free Detection of Proteins
by Khaled Alsabbagh, Tim Hornung, Achim Voigt, Sahba Sadir, Taleieh Rajabi and Kerstin Länge
Biosensors 2021, 11(3), 80; https://doi.org/10.3390/bios11030080 - 13 Mar 2021
Cited by 14 | Viewed by 3255
Abstract
A microfluidic chip for electrochemical impedance spectroscopy (EIS) is presented as bio-sensor for label-free detection of proteins by using the example of cardiac troponin I. Troponin I is one of the most specific diagnostic serum biomarkers for myocardial infarction. The microfluidic impedance biosensor [...] Read more.
A microfluidic chip for electrochemical impedance spectroscopy (EIS) is presented as bio-sensor for label-free detection of proteins by using the example of cardiac troponin I. Troponin I is one of the most specific diagnostic serum biomarkers for myocardial infarction. The microfluidic impedance biosensor chip presented here consists of a microscope glass slide serving as base plate, sputtered electrodes, and a polydimethylsiloxane (PDMS) microchannel. Electrode functionalization protocols were developed considering a possible charge transfer through the sensing layer, in addition to analyte-specific binding by corresponding antibodies and reduction of nonspecific protein adsorption to prevent false-positive signals. Reagents tested for self-assembled monolayers (SAMs) on gold electrodes included thiolated hydrocarbons and thiolated oligonucleotides, where SAMs based on the latter showed a better performance. The corresponding antibody was covalently coupled on the SAM using carbodiimide chemistry. Sampling and measurement took only a few minutes. Application of a human serum albumin (HSA) sample, 1000 ng/mL, led to negligible impedance changes, while application of a troponin I sample, 1 ng/mL, led to a significant shift in the Nyquist plot. The results are promising regarding specific detection of clinically relevant concentrations of biomarkers, such as cardiac markers, with the newly developed microfluidic impedance biosensor chip. Full article
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18 pages, 2664 KiB  
Review
Molecularly Imprinted Polymer-Quantum Dot Materials in Optical Sensors: An Overview of Their Synthesis and Applications
by Myriam Díaz-Álvarez and Antonio Martín-Esteban
Biosensors 2021, 11(3), 79; https://doi.org/10.3390/bios11030079 - 13 Mar 2021
Cited by 32 | Viewed by 5134
Abstract
In the last decades analytical methods have focused on the determination of target analytes at very low concentration levels. This has been accomplished through the use of traditional analytical methods that usually require high reagent consumption, expensive equipment and long pretreatment steps. Thus, [...] Read more.
In the last decades analytical methods have focused on the determination of target analytes at very low concentration levels. This has been accomplished through the use of traditional analytical methods that usually require high reagent consumption, expensive equipment and long pretreatment steps. Thus, there is a demand for simple, rapid, highly selective and user-friendly detection procedures. Quantum dots (QDs) are semiconductor fluorescent nanomaterials with unique optoelectronic properties that have shown great potential for the development of fluorescence probes. Besides, the combination of QDs with molecularly imprinted polymer (MIPs), synthetic materials with selective recognition, have been proposed as useful materials in the development of optical sensors. The resulting MIP-QDs optical sensors integrate the advantages of both techniques: the high sensitivity of QDs-based fluorescence sensors and the high selectivity of MIPs. This review gives a brief overview of the strategies for the synthesis of MIPs-QDs based optical sensors, highlighting the modifications in the synthesis procedure that improve the sensor performance. Finally, a revision of recent applications in sensing and bioimaging is presented. Full article
(This article belongs to the Special Issue Molecularly Imprinted Polymers (MIPs) Biosensors)
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11 pages, 1718 KiB  
Article
Effect of Electrolyte Concentration on Cell Sensing by Measuring Ionic Current Waveform through Micropores
by Kazumichi Yokota, Muneaki Hashimoto, Kazuaki Kajimoto, Masato Tanaka, Sanae Murayama, Makusu Tsutsui, Yoshihiro Nakajima, Masateru Taniguchi and Masatoshi Kataoka
Biosensors 2021, 11(3), 78; https://doi.org/10.3390/bios11030078 - 12 Mar 2021
Cited by 2 | Viewed by 2011
Abstract
Immunostaining has been widely used in cancer prognosis for the quantitative detection of cancer cells present in the bloodstream. However, conventional detection methods based on the target membrane protein expression exhibit the risk of missing cancer cells owing to variable protein expressions. In [...] Read more.
Immunostaining has been widely used in cancer prognosis for the quantitative detection of cancer cells present in the bloodstream. However, conventional detection methods based on the target membrane protein expression exhibit the risk of missing cancer cells owing to variable protein expressions. In this study, the resistive pulse method (RPM) was employed to discriminate between cultured cancer cells (NCI-H1650) and T lymphoblastoid leukemia cells (CCRF-CEM) by measuring the ionic current response of cells flowing through a micro-space. The height and shape of a pulse signal were used for the simultaneous measurement of size, deformability, and surface charge of individual cells. An accurate discrimination of cancer cells could not be obtained using 1.0 × phosphate-buffered saline (PBS) as an electrolyte solution to compare the size measurements by a microscopic observation. However, an accurate discrimination of cancer cells with a discrimination error rate of 4.5 ± 0.5% was achieved using 0.5 × PBS containing 2.77% glucose as the electrolyte solution. The potential application of RPM for the accurate discrimination of cancer cells from leukocytes was demonstrated through the measurement of the individual cell size, deformability, and surface charge in a solution with a low electrolyte concentration. Full article
(This article belongs to the Special Issue Micro- and Nanopore Biosensors)
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9 pages, 508 KiB  
Communication
Superior Adaptations in Adolescent Runners Using Heart Rate Variability (HRV)-Guided Training at Altitude
by Petr Bahenský and Gregory J. Grosicki
Biosensors 2021, 11(3), 77; https://doi.org/10.3390/bios11030077 - 11 Mar 2021
Cited by 5 | Viewed by 5750
Abstract
We evaluated the efficacy of heart rate variability (HRV)-guided training in adolescent athletes during a 2-week, high altitude (≈1900 m) training camp. Sixteen middle- and long-distance runners (4 female/12 male, 16.9 ± 1.0 years, 65.44 ± 4.03 mL·kg−1·min−1) were [...] Read more.
We evaluated the efficacy of heart rate variability (HRV)-guided training in adolescent athletes during a 2-week, high altitude (≈1900 m) training camp. Sixteen middle- and long-distance runners (4 female/12 male, 16.9 ± 1.0 years, 65.44 ± 4.03 mL·kg−1·min−1) were divided into 2 matched groups, both of which received the same training plan, but one of which acquired postwaking HRV values that were used to tailor the training prescription. During the camp, seven athletes in the HRV-guided group combined for a total of 32 training adjustments, whereas there were only 3 runners combined for 14 total training adjustments in the control group. A significant group by time interaction (p < 0.001) for VO2max was driven by VO2max improvements in the HRV group (+2.8 mL·kg−1·min−1, +4.27%; pBonf = 0.002) that were not observed in the control condition (+0.8 mL·kg−1·min−1, +1.26%; pBonf = 0.643). After returning from the camp, all athletes in the HRV group set a personal best, and six out of eight achieved their best positions in the National Championship, whereas only 75% of athletes in the control group set a personal best and five out of eight achieved their best positions in the National Championship. These data provide evidence in support of HRV-guided training as a way to optimize training prescriptions in adolescent athletes. Full article
(This article belongs to the Special Issue Smartphone-Based Biosensors and Diagnostics)
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11 pages, 1862 KiB  
Article
2LTRZFP Interacts Specifically to HIV-1 DNA without Off-Target Effects as Determined by Biolayer Interferometry
by Koollawat Chupradit, Weeraya Thongkum, On-anong Juntit, Kanokporn Sornsuwan and Chatchai Tayapiwatana
Biosensors 2021, 11(3), 76; https://doi.org/10.3390/bios11030076 - 8 Mar 2021
Cited by 1 | Viewed by 2299
Abstract
Protein and DNA interactions are crucial for many cellular processes. Biolayer Interferometry (BLI) is a label-free technology for determining kinetic biomolecular interactions with high accuracy results. In the present study, we determined the kinetic binding of a zinc finger scaffold, 2LTRZFP, which formerly [...] Read more.
Protein and DNA interactions are crucial for many cellular processes. Biolayer Interferometry (BLI) is a label-free technology for determining kinetic biomolecular interactions with high accuracy results. In the present study, we determined the kinetic binding of a zinc finger scaffold, 2LTRZFP, which formerly constructed the interfering effect on HIV-1 integration process using BLI. The competitive Enzyme-linked immunosorbent assay (ELISA) was used to initially show the specific binding of 2LTRZFP. The percentages of inhibition were 62% and 22% in double-stranded 2LTR (ds2LTR) and irrelevant DNA (dsNeg), respectively. Consequently, the binding affinity of 2LTRZFP against ds2LTR target analyzed by BLI was 40 nM, which is stronger than the interaction of HIV-1 integrase (IN) enzyme to the 2LTR circle junction. Additionally, the 2LTRZFP did not interact with the genomic DNA extracted from SupT1 cell line. This result indicates that 2LTRZFP did not exhibit off-target effects against human genome. The knowledge obtained from this study supports the prospect of using 2LTRZFP in HIV-1 gene therapy. Full article
(This article belongs to the Special Issue Advanced Biosensing Technologies in Medical Applications)
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12 pages, 2467 KiB  
Article
Biosensing Amplification by Hybridization Chain Reaction on Phase-Sensitive Surface Plasmon Resonance
by Ching-Hsu Yang, Tzu-Heng Wu, Chia-Chen Chang, Hui-Yun Lo, Hui-Wen Liu, Nien-Tsu Huang and Chii-Wann Lin
Biosensors 2021, 11(3), 75; https://doi.org/10.3390/bios11030075 - 6 Mar 2021
Cited by 9 | Viewed by 3403
Abstract
Surface Plasmon Resonance (SPR) is widely used in biological and chemical sensing with fascinating properties. However, the application of SPR to detect trace targets is hampered by non-specific binding and poor signal. A variety of approaches for amplification have been explored to overcome [...] Read more.
Surface Plasmon Resonance (SPR) is widely used in biological and chemical sensing with fascinating properties. However, the application of SPR to detect trace targets is hampered by non-specific binding and poor signal. A variety of approaches for amplification have been explored to overcome this deficiency including DNA aptamers as versatile target detection tools. Hybridization chain reaction (HCR) is a high-efficiency enzyme-free DNA amplification method operated at room temperature, in which two stable species of DNA hairpins coexist in solution until the introduction of the initiator strand triggers a cascade of hybridization events. At an optimal salt condition, as the concentrations of H1 and H2 increased, the HCR signals were enhanced, leading to signal amplification reaching up to 6.5-fold of the detection measure at 30 min. This feature enables DNA to act as an amplifying transducer for biosensing applications to provide an enzyme-free alternative that can easily detect complex DNA sequences. Improvement of more diverse recognition events can be achieved by integrating HCR with a phase-sensitive SPR (pSPR)-tested aptamer stimulus. This work seeks to establish pSPR aptamer system for highly informative sensing by means of an amplification HCR. Thus, combining pSPR and HCR technologies provide an expandable platform for sensitive biosensing. Full article
(This article belongs to the Special Issue Emerging Nanoplasmonic Technologies in Biosensors)
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16 pages, 2130 KiB  
Article
Rapid Detection of Pathogens in Wound Exudate via Nucleic Acid Lateral Flow Immunoassay
by Anna Brunauer, René D. Verboket, Daniel M. Kainz, Felix von Stetten and Susanna M. Früh
Biosensors 2021, 11(3), 74; https://doi.org/10.3390/bios11030074 - 6 Mar 2021
Cited by 15 | Viewed by 4573
Abstract
The rapid detection of pathogens in infected wounds can significantly improve the clinical outcome. Wound exudate, which can be collected in a non-invasive way, offers an attractive sample material for the detection of pathogens at the point-of-care (POC). Here, we report the development [...] Read more.
The rapid detection of pathogens in infected wounds can significantly improve the clinical outcome. Wound exudate, which can be collected in a non-invasive way, offers an attractive sample material for the detection of pathogens at the point-of-care (POC). Here, we report the development of a nucleic acid lateral flow immunoassay for direct detection of isothermally amplified DNA combined with fast sample preparation. The streamlined protocol was evaluated using human wound exudate spiked with the opportunistic pathogen Pseudomonas aeruginosa that cause severe health issues upon wound colonization. A detection limit of 2.1 × 105 CFU per mL of wound fluid was achieved, and no cross-reaction with other pathogens was observed. Furthermore, we integrated an internal amplification control that excludes false negative results and, in combination with the flow control, ensures the validity of the test result. The paper-based approach with only three simple hands-on steps has a turn-around time of less than 30 min and covers the complete analytical process chain from sample to answer. This newly developed workflow for wound fluid diagnostics has tremendous potential for reliable pathogen POC testing and subsequent target-oriented therapy. Full article
(This article belongs to the Section Biosensors and Healthcare)
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15 pages, 2218 KiB  
Article
Siphon-Controlled Automation on a Lab-on-a-Disc Using Event-Triggered Dissolvable Film Valves
by Brian D. Henderson, David J. Kinahan, Jeanne Rio, Rohit Mishra, Damien King, Sarai M. Torres-Delgado, Dario Mager, Jan G. Korvink and Jens Ducrée
Biosensors 2021, 11(3), 73; https://doi.org/10.3390/bios11030073 - 6 Mar 2021
Cited by 12 | Viewed by 3397
Abstract
Within microfluidic technologies, the centrifugal microfluidic “Lab-on-a-Disc” (LoaD) platform offers great potential for use at the PoC and in low-resource settings due to its robustness and the ability to port and miniaturize ‘wet bench’ laboratory protocols. We present the combination of ‘event-triggered dissolvable [...] Read more.
Within microfluidic technologies, the centrifugal microfluidic “Lab-on-a-Disc” (LoaD) platform offers great potential for use at the PoC and in low-resource settings due to its robustness and the ability to port and miniaturize ‘wet bench’ laboratory protocols. We present the combination of ‘event-triggered dissolvable film valves’ with a centrifugo-pneumatic siphon structure to enable control and timing, through changes in disc spin-speed, of the release and incubations of eight samples/reagents/wash buffers. Based on these microfluidic techniques, we integrated and automated a chemiluminescent immunoassay for detection of the CVD risk factor marker C-reactive protein displaying a limit of detection (LOD) of 44.87 ng mL−1 and limit of quantitation (LoQ) of 135.87 ng mL−1. Full article
(This article belongs to the Special Issue Biosensors for Rapid Diagnostics)
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12 pages, 4267 KiB  
Article
SPR-Optical Fiber-Molecularly Imprinted Polymer Sensor for the Detection of Furfural in Wine
by Maria Pesavento, Luigi Zeni, Letizia De Maria, Giancarla Alberti and Nunzio Cennamo
Biosensors 2021, 11(3), 72; https://doi.org/10.3390/bios11030072 - 5 Mar 2021
Cited by 39 | Viewed by 3866
Abstract
A surface plasmon resonance (SPR) platform, based on a D-shaped plastic optical fiber (POF), combined with a biomimetic receptor, i.e., a molecularly imprinted polymer (MIP), is proposed to detect furfural (2-furaldheide, 2-FAL) in fermented beverages like wine. MIPs have been demonstrated to be [...] Read more.
A surface plasmon resonance (SPR) platform, based on a D-shaped plastic optical fiber (POF), combined with a biomimetic receptor, i.e., a molecularly imprinted polymer (MIP), is proposed to detect furfural (2-furaldheide, 2-FAL) in fermented beverages like wine. MIPs have been demonstrated to be a very convenient biomimetic receptor in the proposed sensing device, being easy and rapid to develop, suitable for on-site determinations at low concentrations, and cheap. Moreover, the MIP film thickness can be changed to modulate the sensing parameters. The possibility of performing single drop measurements is a further favorable aspect for practical applications. For example, the use of an SPR-MIP sensor for the analysis of 2-FAL in a real life matrix such as wine is proposed, obtaining a low detection limit of 0.004 mg L−1. The determination of 2-FAL in fermented beverages is becoming a crucial task, mainly for the effects of the furanic compounds on the flavor of food and their toxic and carcinogenic effect on human beings. Full article
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19 pages, 3966 KiB  
Review
Food Safety in Post-COVID-19 Pandemic: Challenges and Countermeasures
by Weimin Zhang, Huiyu He, Lin Zhu, Guozhen Liu and Long Wu
Biosensors 2021, 11(3), 71; https://doi.org/10.3390/bios11030071 - 4 Mar 2021
Cited by 21 | Viewed by 7275
Abstract
Understanding food safety hazard risks is essential to avoid potential negative heath impacts in the food supply chain in a post-COVID-19 pandemic era. Development of strategies for virus direction in foods plays an important role in food safety and verification. Early warning, tracing, [...] Read more.
Understanding food safety hazard risks is essential to avoid potential negative heath impacts in the food supply chain in a post-COVID-19 pandemic era. Development of strategies for virus direction in foods plays an important role in food safety and verification. Early warning, tracing, and detection should be implemented as an integrated system in order to mitigate thecoronavirus disease 2019 (COVID-19) outbreak, in which the detection of severe acute respiratory syndrome coronavirus-2 (SARS-CoV-2) is critical as it not only concerns screening of populations but also monitoring of possible contaminated sources such as the food supply chain. In this review, we point out the consequences in different aspects of our daily life in the post-COVID-19 pandemic from the perspective of the food supply chain and the food industry. We summarize the possible transmission routes of COVID-19 in the food supply chain before exploring the development of corresponding detection tools of SARS-CoV-2. Accordingly, we compare different detection methods for the virus in foods, including different pretreatments of food matrices in the virus detection. Finally, the future perspectives are proposed. Full article
(This article belongs to the Collection Biosensors for Point-of-Care Diagnostics)
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12 pages, 723 KiB  
Perspective
Glycated Hemoglobin and Methods for Its Point of Care Testing
by Miroslav Pohanka
Biosensors 2021, 11(3), 70; https://doi.org/10.3390/bios11030070 - 4 Mar 2021
Cited by 22 | Viewed by 7686
Abstract
Glycated hemoglobin (HbA1c) is a product of the spontaneous reaction between hemoglobin and elevated glucose levels in the blood. It is included among the so-called advanced glycation end products, of which is the most important for the clinical diagnosis of diabetes [...] Read more.
Glycated hemoglobin (HbA1c) is a product of the spontaneous reaction between hemoglobin and elevated glucose levels in the blood. It is included among the so-called advanced glycation end products, of which is the most important for the clinical diagnosis of diabetes mellitus, and it can serve as an alternative to glycemia measurement. Compared to the diagnosis of diabetes mellitus by glycemia, the HbA1c level is less influenced by a short-term problem with diabetes compensation. Mass spectroscopy and chromatographic techniques are among the standard methods of HbA1c level measurement. Compared to glycemia measurement, there is lack of simple methods for diabetes mellitus diagnosis by means of the HbA1c assay using a point-of-care test. This review article is focused on the surveying of facts about HbA1c and its importance in diabetes mellitus diagnosis, and surveying standard methods and new methods suitable for the HbA1c assay under point-of-care conditions. Various bioassays and biosensors are mentioned and their specifications are discussed. Full article
(This article belongs to the Special Issue New Developments for Efficient Rapid Bioassays)
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22 pages, 4295 KiB  
Article
Automatic Premature Ventricular Contraction Detection Using Deep Metric Learning and KNN
by Junsheng Yu, Xiangqing Wang, Xiaodong Chen and Jinglin Guo
Biosensors 2021, 11(3), 69; https://doi.org/10.3390/bios11030069 - 4 Mar 2021
Cited by 24 | Viewed by 4178
Abstract
Premature ventricular contractions (PVCs), common in the general and patient population, are irregular heartbeats that indicate potential heart diseases. Clinically, long-term electrocardiograms (ECG) collected from the wearable device is a non-invasive and inexpensive tool widely used to diagnose PVCs by physicians. However, analyzing [...] Read more.
Premature ventricular contractions (PVCs), common in the general and patient population, are irregular heartbeats that indicate potential heart diseases. Clinically, long-term electrocardiograms (ECG) collected from the wearable device is a non-invasive and inexpensive tool widely used to diagnose PVCs by physicians. However, analyzing these long-term ECG is time-consuming and labor-intensive for cardiologists. Therefore, this paper proposed a simplistic but powerful approach to detect PVC from long-term ECG. The suggested method utilized deep metric learning to extract features, with compact intra-product variance and separated inter-product differences, from the heartbeat. Subsequently, the k-nearest neighbors (KNN) classifier calculated the distance between samples based on these features to detect PVC. Unlike previous systems used to detect PVC, the proposed process can intelligently and automatically extract features by supervised deep metric learning, which can avoid the bias caused by manual feature engineering. As a generally available set of standard test material, the MIT-BIH (Massachusetts Institute of Technology-Beth Israel Hospital) Arrhythmia Database is used to evaluate the proposed method, and the experiment takes 99.7% accuracy, 97.45% sensitivity, and 99.87% specificity. The simulation events show that it is reliable to use deep metric learning and KNN for PVC recognition. More importantly, the overall way does not rely on complicated and cumbersome preprocessing. Full article
(This article belongs to the Special Issue Intelligent Biosignal Processing in Wearable and Implantable Sensors)
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16 pages, 3293 KiB  
Article
Electronic Eye Based on RGB Analysis for the Identification of Tequilas
by Anais Gómez, Diana Bueno and Juan Manuel Gutiérrez
Biosensors 2021, 11(3), 68; https://doi.org/10.3390/bios11030068 - 2 Mar 2021
Cited by 12 | Viewed by 3488
Abstract
The present work reports the development of a biologically inspired analytical system known as Electronic Eye (EE), capable of qualitatively discriminating different tequila categories. The reported system is a low-cost and portable instrumentation based on a Raspberry Pi single-board computer and an 8 [...] Read more.
The present work reports the development of a biologically inspired analytical system known as Electronic Eye (EE), capable of qualitatively discriminating different tequila categories. The reported system is a low-cost and portable instrumentation based on a Raspberry Pi single-board computer and an 8 Megapixel CMOS image sensor, which allow the collection of images of Silver, Aged, and Extra-aged tequila samples. Image processing is performed mimicking the trichromatic theory of color vision using an analysis of Red, Green, and Blue components (RGB) for each image’s pixel. Consequently, RGB absorbances of images were evaluated and preprocessed, employing Principal Component Analysis (PCA) to visualize data clustering. The resulting PCA scores were modeled with a Linear Discriminant Analysis (LDA) that accomplished the qualitative classification of tequilas. A Leave-One-Out Cross-Validation (LOOCV) procedure was performed to evaluate classifiers’ performance. The proposed system allowed the identification of real tequila samples achieving an overall classification rate of 90.02%, average sensitivity, and specificity of 0.90 and 0.96, respectively, while Cohen’s kappa coefficient was 0.87. In this case, the EE has demonstrated a favorable capability to correctly discriminated and classified the different tequila samples according to their categories. Full article
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11 pages, 2637 KiB  
Article
Developing a Quantifying Device for Soft Tissue Material Properties around Lumbar Spines
by Song Joo Lee, Yong-Eun Cho, Kyung-Hyun Kim and Deukhee Lee
Biosensors 2021, 11(3), 67; https://doi.org/10.3390/bios11030067 - 28 Feb 2021
Cited by 3 | Viewed by 2071
Abstract
Knowing the material properties of the musculoskeletal soft tissue could be important to develop rehabilitation therapy and surgical procedures. However, there is a lack of devices and information on the viscoelastic properties of soft tissues around the lumbar spine. The goal of this [...] Read more.
Knowing the material properties of the musculoskeletal soft tissue could be important to develop rehabilitation therapy and surgical procedures. However, there is a lack of devices and information on the viscoelastic properties of soft tissues around the lumbar spine. The goal of this study was to develop a portable quantifying device for providing strain and stress curves of muscles and ligaments around the lumbar spine at various stretching speeds. Each sample was conditioned and applied for 20 repeatable cyclic 5 mm stretch-and-relax trials in the direction and perpendicular direction of the fiber at 2, 3 and 5 mm/s. Our device successfully provided the stress and strain curve of the samples and our results showed that there were significant effects of speed on the young’s modulus of the samples (p < 0.05). Compared to the expensive commercial device, our lower-cost device provided comparable stress and strain curves of the sample. Based on our device and findings, various sizes of samples can be measured and viscoelastic properties of the soft tissues can be obtained. Our portable device and approach can help to investigate young’s modulus of musculoskeletal soft tissues conveniently, and can be a basis for developing a material testing device in a surgical room or various lab environments. Full article
(This article belongs to the Section Biosensor and Bioelectronic Devices)
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30 pages, 6211 KiB  
Review
A Review on SERS-Based Detection of Human Virus Infections: Influenza and Coronavirus
by Fernanda Saviñon-Flores, Erika Méndez, Mónica López-Castaños, Alejandro Carabarin-Lima, Karen A. López-Castaños, Miguel A. González-Fuentes and Alia Méndez-Albores
Biosensors 2021, 11(3), 66; https://doi.org/10.3390/bios11030066 - 28 Feb 2021
Cited by 65 | Viewed by 7939
Abstract
The diagnosis of respiratory viruses of zoonotic origin (RVsZO) such as influenza and coronaviruses in humans is crucial, because their spread and pandemic threat are the highest. Surface–enhanced Raman spectroscopy (SERS) is an analytical technique with promising impact for the point–of–care diagnosis of [...] Read more.
The diagnosis of respiratory viruses of zoonotic origin (RVsZO) such as influenza and coronaviruses in humans is crucial, because their spread and pandemic threat are the highest. Surface–enhanced Raman spectroscopy (SERS) is an analytical technique with promising impact for the point–of–care diagnosis of viruses. It has been applied to a variety of influenza A virus subtypes, such as the H1N1 and the novel coronavirus SARS−CoV−2. In this work, a review of the strategies used for the detection of RVsZO by SERS is presented. In addition, relevant information about the SERS technique, anthropozoonosis, and RVsZO is provided for a better understanding of the theme. The direct identification is based on trapping the viruses within the interstices of plasmonic nanoparticles and recording the SERS signal from gene fragments or membrane proteins. Quantitative mono- and multiplexed assays have been achieved following an indirect format through a SERS-based sandwich immunoassay. Based on this review, the development of multiplex assays that incorporate the detection of RVsZO together with their specific biomarkers and/or secondary disease biomarkers resulting from the infection progress would be desirable. These configurations could be used as a double confirmation or to evaluate the health condition of the patient. Full article
(This article belongs to the Special Issue Biosensors for Healthcare and Disease Diagnosis)
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