Biosensors

Research

19 pages, 2106 KiB

Open AccessArticle

Rapid Multiplex Strip Test for the Detection of Circulating Tumor DNA Mutations for Liquid Biopsy Applications

by Panagiota M. Kalligosfyri, Sofia Nikou, Sofia Karteri, Haralabos P. Kalofonos, Vasiliki Bravou and Despina P. Kalogianni

Biosensors 2022, 12(2), 97; https://doi.org/10.3390/bios12020097 - 4 Feb 2022

Cited by 12 | Viewed by 4589

Abstract

In the era of personalized medicine, molecular profiling of patient tumors has become the standard practice, especially for patients with advanced disease. Activating point mutations of the KRAS proto-oncogene are clinically relevant for many types of cancer, including colorectal cancer (CRC). While several [...] Read more.

In the era of personalized medicine, molecular profiling of patient tumors has become the standard practice, especially for patients with advanced disease. Activating point mutations of the KRAS proto-oncogene are clinically relevant for many types of cancer, including colorectal cancer (CRC). While several approaches have been developed for tumor genotyping, liquid biopsy has been gaining much attention in the clinical setting. Analysis of circulating tumor DNA for genetic alterations has been challenging, and many methodologies with both advantages and disadvantages have been developed. We here developed a gold nanoparticle-based rapid strip test that has been applied for the first time for the multiplex detection of KRAS mutations in circulating tumor DNA (ctDNA) of CRC patients. The method involved ctDNA isolation, PCR-amplification of the KRAS gene, multiplex primer extension (PEXT) reaction, and detection with a multiplex strip test. We have optimized the efficiency and specificity of the multiplex strip test in synthetic DNA targets, in colorectal cancer cell lines, in tissue samples, and in blood-derived ctDNA from patients with advanced colorectal cancer. The proposed strip test achieved rapid and easy multiplex detection (normal allele and three major single-point mutations) of the clinically relevant KRAS mutations in ctDNA in blood samples of CRC patients with high specificity and repeatability. This multiplex strip test represents a minimally invasive, rapid, low-cost, and promising diagnostic tool for the detection of clinically relevant mutations in cancer patients. Full article

(This article belongs to the Special Issue Biosensors for Diagnosis and Monitoring)

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14 pages, 3820 KiB

Open AccessArticle

Electrochemical Detection Platform Based on RGO Functionalized with Diazonium Salt for DNA Hybridization

by Elena A. Chiticaru, Luisa Pilan and Mariana Ioniţă

Biosensors 2022, 12(1), 39; https://doi.org/10.3390/bios12010039 - 13 Jan 2022

Cited by 8 | Viewed by 3233

Abstract

In this paper, we propose an improved electrochemical platform based on graphene for the detection of DNA hybridization. Commercial screen-printed carbon electrodes (SPCEs) were used for this purpose due to their ease of functionalization and miniaturization opportunities. SPCEs were modified with reduced graphene [...] Read more.

In this paper, we propose an improved electrochemical platform based on graphene for the detection of DNA hybridization. Commercial screen-printed carbon electrodes (SPCEs) were used for this purpose due to their ease of functionalization and miniaturization opportunities. SPCEs were modified with reduced graphene oxide (RGO), offering a suitable surface for further functionalization. Therefore, aryl-carboxyl groups were integrated onto RGO-modified electrodes by electrochemical reduction of the corresponding diazonium salt to provide enough reaction sites for the covalent immobilization of amino-modified DNA probes. Our final goal was to determine the optimum conditions needed to fabricate a simple, label-free RGO-based electrochemical platform to detect the hybridization between two complementary single-stranded DNA molecules. Each modification step in the fabrication process was monitored by cyclic voltammetry (CV) and electrochemical impedance spectroscopy (EIS) using [Fe(CN)₆]^3−/4− as a redox reporter. Although, the diazonium electrografted layer displayed the expected blocking effect of the charge transfer, the next steps in the modification procedure resulted in enhanced electron transfer properties of the electrode interface. We suggest that the improvement in the charge transfer after the DNA hybridization process could be exploited as a prospective sensing feature. The morphological and structural characterization of the modified electrodes performed by scanning electron microscopy (SEM) and Raman spectroscopy, respectively, were used to validate different modification steps in the platform fabrication process. Full article

(This article belongs to the Special Issue Biosensors for Diagnosis and Monitoring)

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12 pages, 1965 KiB

Open AccessArticle

Development of a Microfluidic Device for CD4⁺ T Cell Isolation and Automated Enumeration from Whole Blood

by Robert D. Fennell, Mazhar Sher and Waseem Asghar

Biosensors 2022, 12(1), 12; https://doi.org/10.3390/bios12010012 - 28 Dec 2021

Cited by 6 | Viewed by 2236

Abstract

The development of point-of-care, cost-effective, and easy-to-use assays for the accurate counting of CD4⁺ T cells remains an important focus for HIV-1 disease management. The CD4⁺ T cell count provides an indication regarding the overall success of HIV-1 treatments. The CD4 [...] Read more.

The development of point-of-care, cost-effective, and easy-to-use assays for the accurate counting of CD4⁺ T cells remains an important focus for HIV-1 disease management. The CD4⁺ T cell count provides an indication regarding the overall success of HIV-1 treatments. The CD4⁺ T count information is equally important for both resource-constrained regions and areas with extensive resources. Hospitals and other allied facilities may be overwhelmed by epidemics or other disasters. An assay for a physician’s office or other home-based setting is becoming increasingly popular. We have developed a technology for the rapid quantification of CD4⁺ T cells. A double antibody selection process, utilizing anti-CD4 and anti-CD3 antibodies, is tested and provides a high specificity. The assay utilizes a microfluidic chip coated with the anti-CD3 antibody, having an improved antibody avidity. As a result of enhanced binding, a higher flow rate can be applied that enables an improved channel washing to reduce non-specific bindings. A wide-field optical imaging system is also developed that provides the rapid quantification of cells. The designed optical setup is portable and low-cost. An ImageJ-based program is developed for the automatic counting of CD4⁺ T cells. We have successfully isolated and counted CD4⁺ T cells with high specificity and efficiency greater than 90%. Full article

(This article belongs to the Special Issue Biosensors for Diagnosis and Monitoring)

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14 pages, 2615 KiB

Open AccessArticle

RF Remote Blood Glucose Sensor and a Microfluidic Vascular Phantom for Sensor Validation

by Muhammad Farhan Affendi Mohamad Yunos, Rémi Manczak, Cyril Guines, Ahmad Fairuzabadi Mohd Mansor, Wing Cheung Mak, Sheroz Khan, Noor Amalina Ramli, Arnaud Pothier and Anis Nurashikin Nordin

Biosensors 2021, 11(12), 494; https://doi.org/10.3390/bios11120494 - 3 Dec 2021

Cited by 11 | Viewed by 4608

Abstract

Diabetes has become a major health problem in society. Invasive glucometers, although precise, only provide discrete measurements at specific times and are unsuitable for long-term monitoring due to the injuries caused on skin and the prohibitive cost of disposables. Remote, continuous, self-monitoring of [...] Read more.

Diabetes has become a major health problem in society. Invasive glucometers, although precise, only provide discrete measurements at specific times and are unsuitable for long-term monitoring due to the injuries caused on skin and the prohibitive cost of disposables. Remote, continuous, self-monitoring of blood sugar levels allows for active and better management of diabetics. In this work, we present a radio frequency (RF) sensor based on a stepped impedance resonator for remote blood glucose monitoring. When placed on top of a human hand, this RF interdigital sensor allows detection of variation in blood sugar levels by monitoring the changes in the dielectric constant of the material underneath. The designed stepped impedance resonator operates at 3.528 GHz with a Q factor of 1455. A microfluidic device structure that imitates the blood veins in the human hand was fabricated in PDMS to validate that the sensor can measure changes in glucose concentrations. To test the RF sensor, glucose solutions with concentrations ranging from 0 to 240 mg/dL were injected into the fluidic channels and placed underneath the RF sensor. The shifts in the resonance frequencies of the RF sensor were measured using a network analyzer via its S₁₁ parameters. Based on the change in resonance frequencies, the sensitivity of the biosensor was found to be 264.2 kHz/mg·dL⁻¹ and its LOD was calculated to be 29.89 mg/dL. Full article

(This article belongs to the Special Issue Biosensors for Diagnosis and Monitoring)

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12 pages, 1949 KiB

Open AccessArticle

Plastic Antibody of Polypyrrole/Multiwall Carbon Nanotubes on Screen-Printed Electrodes for Cystatin C Detection

by Rui S. Gomes, Blanca Azucena Gomez-Rodríguez, Ruben Fernandes, M. Goreti F. Sales, Felismina T. C. Moreira and Rosa F. Dutra

Biosensors 2021, 11(6), 175; https://doi.org/10.3390/bios11060175 - 31 May 2021

Cited by 18 | Viewed by 4089

Abstract

This work reports the design of a novel plastic antibody for cystatin C (Cys-C), an acute kidney injury biomarker, and its application in point-of-care (PoC) testing. The synthetic antibody was obtained by tailoring a molecularly imprinted polymer (MIP) on a carbon screen-printed electrode [...] Read more.

This work reports the design of a novel plastic antibody for cystatin C (Cys-C), an acute kidney injury biomarker, and its application in point-of-care (PoC) testing. The synthetic antibody was obtained by tailoring a molecularly imprinted polymer (MIP) on a carbon screen-printed electrode (SPE). The MIP was obtained by electropolymerizing pyrrole (Py) with carboxylated Py (Py-COOH) in the presence of Cys-C and multiwall carbon nanotubes (MWCNTs). Cys-C was removed from the molecularly imprinted poly(Py) matrix (MPPy) by urea treatment. As a control, a non-imprinted poly(Py) matrix (NPPy) was obtained by the same procedure, but without Cys-C. The assembly of the MIP material was evaluated in situ by Raman spectroscopy and the binding ability of Cys-C was evaluated by the cyclic voltammetry (CV) and differential pulse voltammetry (DPV) electrochemical techniques. The MIP sensor responses were measured by the DPV anodic peaks obtained in the presence of ferro/ferricyanide. The peak currents decreased linearly from 0.5 to 20.0 ng/mL of Cys-C at each 20 min successive incubation and a limit of detection below 0.5 ng/mL was obtained at pH 6.0. The MPPy/SPE was used to analyze Cys-C in spiked serum samples, showing recoveries <3%. This device showed promising features in terms of simplicity, cost and sensitivity for acute kidney injury diagnosis at the point of care. Full article

(This article belongs to the Special Issue Biosensors for Diagnosis and Monitoring)

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10 pages, 2033 KiB

Open AccessCommunication

Electrochemical Fingerprint Biosensor for Natural Indigo Dye Yielding Plants Analysis

by Boyuan Fan, Qiong Wang, Weihong Wu, Qinwei Zhou, Dongling Li, Zenglai Xu, Li Fu, Jiangwei Zhu, Hassan Karimi-Maleh and Cheng-Te Lin

Biosensors 2021, 11(5), 155; https://doi.org/10.3390/bios11050155 - 14 May 2021

Cited by 46 | Viewed by 3990

Abstract

Indigo is a plant dye that has been used as an important dye by various ancient civilizations throughout history. Today, due to environmental and health concerns, plant indigo is re-entering the market. Strobilanthes cusia (Nees) Kuntze is the most widely used species [...] Read more.

Indigo is a plant dye that has been used as an important dye by various ancient civilizations throughout history. Today, due to environmental and health concerns, plant indigo is re-entering the market. Strobilanthes cusia (Nees) Kuntze is the most widely used species in China for indigo preparation. However, other species under Strobilanthes have a similar feature. In this work, 12 Strobilanthes spp. were analyzed using electrochemical fingerprinting technology. Depending on their electrochemically active molecules, they can be quickly identified by fingerprinting. In addition, the fingerprint obtained under different conditions can be used to produce scattered patter and heatmap. These patterns make plant identification more convenient. Since the electrochemically active components in plants reflect the differences at the gene level to some extent, the obtained electrochemical fingerprints are further used for the discussion of phylogenetics. Full article

(This article belongs to the Special Issue Biosensors for Diagnosis and Monitoring)

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12 pages, 2387 KiB

Open AccessArticle

Display of Microbial Glucose Dehydrogenase and Cholesterol Oxidase on the Yeast Cell Surface for the Detection of Blood Biochemical Parameters

by Shiyao Zhao, Dong Guo, Quanchao Zhu, Weiwang Dou and Wenjun Guan

Biosensors 2021, 11(1), 13; https://doi.org/10.3390/bios11010013 - 30 Dec 2020

Cited by 15 | Viewed by 3953

Abstract

High levels of blood glucose are always associated with numerous complications including cholesterol abnormalities. Therefore, it is important to simultaneously monitor blood glucose and cholesterol levels in patients with diabetes during the management of chronic diseases. In this study, a glucose dehydrogenase from [...] Read more.

High levels of blood glucose are always associated with numerous complications including cholesterol abnormalities. Therefore, it is important to simultaneously monitor blood glucose and cholesterol levels in patients with diabetes during the management of chronic diseases. In this study, a glucose dehydrogenase from Aspergillus oryzae TI and a cholesterol oxidase from Chromobacterium sp. DS-1 were displayed on the surface of Saccharomyces cerevisiae, respectively, using the yeast surface display system at a high copy number. In addition, two whole-cell biosensors were constructed through the immobilization of the above yeast cells on electrodes, for electrochemical detection of glucose and cholesterol. The assay time was 8.5 s for the glucose biosensors and 30 s for the cholesterol biosensors. Under optimal conditions, the cholesterol biosensor exhibited a linear range from 2 to 6 mmol·L⁻¹. The glucose biosensor responded efficiently to the presence of glucose at a concentration range of 20–600 mg·dL⁻¹ (1.4–33.3 mmol·L⁻¹) and showed excellent anti-xylose interference properties. Both biosensors exhibited good performance at room temperature and remained stable over a three-week storage period. Full article

(This article belongs to the Special Issue Biosensors for Diagnosis and Monitoring)

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12 pages, 13324 KiB

Open AccessArticle

Interdigitated Sensor Optimization for Blood Sample Analysis

by Julien Claudel, Thanh-Tuan Ngo, Djilali Kourtiche and Mustapha Nadi

Biosensors 2020, 10(12), 208; https://doi.org/10.3390/bios10120208 - 16 Dec 2020

Cited by 13 | Viewed by 3664

Abstract

Interdigitated (ITD) sensors are specially adapted for the bioimpedance analysis (BIA) of low-volume (microliter scale) biological samples. Impedance spectroscopy is a fast method involving simple and easy biological sample preparation. The geometry of an ITD sensor makes it easier to deposit a sample [...] Read more.

Interdigitated (ITD) sensors are specially adapted for the bioimpedance analysis (BIA) of low-volume (microliter scale) biological samples. Impedance spectroscopy is a fast method involving simple and easy biological sample preparation. The geometry of an ITD sensor makes it easier to deposit a sample at the microscopic scale of the electrodes. At this scale, the electrode size induces an increase in the double-layer effect, which may completely limit interesting bandwidths in the impedance measurements. This work focuses on ITD sensor frequency band optimization via an original study of the impact of the metalization ratio α. An electrical sensor model was studied to determine the best α ratio. A ratio of 0.6 was able to improve the low-frequency cutoff by a factor of up to 2.5. This theoretical approach was confirmed by measurements of blood samples with three sensors. The optimized sensor was able to extract the intrinsic electrical properties of blood in the frequency band of interest. Full article

(This article belongs to the Special Issue Biosensors for Diagnosis and Monitoring)

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Review

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16 pages, 1784 KiB

Open AccessReview

REASSURED Multiplex Diagnostics: A Critical Review and Forecast

by Jonas A. Otoo and Travis S. Schlappi

Biosensors 2022, 12(2), 124; https://doi.org/10.3390/bios12020124 - 16 Feb 2022

Cited by 59 | Viewed by 7124

Abstract

The diagnosis of infectious diseases is ineffective when the diagnostic test does not meet one or more of the necessary standards of affordability, accessibility, and accuracy. The World Health Organization further clarifies these standards with a set of criteria that has the acronym [...] Read more.

The diagnosis of infectious diseases is ineffective when the diagnostic test does not meet one or more of the necessary standards of affordability, accessibility, and accuracy. The World Health Organization further clarifies these standards with a set of criteria that has the acronym ASSURED (Affordable, Sensitive, Specific, User-friendly, Rapid and robust, Equipment-free and Deliverable to end-users). The advancement of the digital age has led to a revision of the ASSURED criteria to REASSURED: Real-time connectivity, Ease of specimen collection, Affordable, Sensitive, Specific, User-friendly, Rapid and robust, Equipment-free or simple, and Deliverable to end-users. Many diagnostic tests have been developed that aim to satisfy the REASSURED criteria; however, most of them only detect a single target. With the progression of syndromic infections, coinfections and the current antimicrobial resistance challenges, the need for multiplexed diagnostics is now more important than ever. This review summarizes current diagnostic technologies for multiplexed detection and forecasts which methods have promise for detecting multiple targets and meeting all REASSURED criteria. Full article

(This article belongs to the Special Issue Biosensors for Diagnosis and Monitoring)

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27 pages, 4072 KiB

Open AccessReview

Paving the Way for a Green Transition in the Design of Sensors and Biosensors for the Detection of Volatile Organic Compounds (VOCs)

by Camilla Maria Cova, Esther Rincón, Eduardo Espinosa, Luis Serrano and Alessio Zuliani

Biosensors 2022, 12(2), 51; https://doi.org/10.3390/bios12020051 - 19 Jan 2022

Cited by 32 | Viewed by 6837

Abstract

The efficient and selective detection of volatile organic compounds (VOCs) provides key information for various purposes ranging from the toxicological analysis of indoor/outdoor environments to the diagnosis of diseases or to the investigation of biological processes. In the last decade, different sensors and [...] Read more.

The efficient and selective detection of volatile organic compounds (VOCs) provides key information for various purposes ranging from the toxicological analysis of indoor/outdoor environments to the diagnosis of diseases or to the investigation of biological processes. In the last decade, different sensors and biosensors providing reliable, rapid, and economic responses in the detection of VOCs have been successfully conceived and applied in numerous practical cases; however, the global necessity of a sustainable development, has driven the design of devices for the detection of VOCs to greener methods. In this review, the most recent and innovative VOC sensors and biosensors with sustainable features are presented. The sensors are grouped into three of the main industrial sectors of daily life, including environmental analysis, highly important for toxicity issues, food packaging tools, especially aimed at avoiding the spoilage of meat and fish, and the diagnosis of diseases, crucial for the early detection of relevant pathological conditions such as cancer and diabetes. The research outcomes presented in the review underly the necessity of preparing sensors with higher efficiency, lower detection limits, improved selectivity, and enhanced sustainable characteristics to fully address the sustainable manufacturing of VOC sensors and biosensors. Full article

(This article belongs to the Special Issue Biosensors for Diagnosis and Monitoring)

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30 pages, 1871 KiB

Open AccessReview

Novel Biorecognition Elements against Pathogens in the Design of State-of-the-Art Diagnostics

by Maria G. Sande, Joana L. Rodrigues, Débora Ferreira, Carla J. Silva and Ligia R. Rodrigues

Biosensors 2021, 11(11), 418; https://doi.org/10.3390/bios11110418 - 26 Oct 2021

Cited by 29 | Viewed by 6324

Abstract

Infectious agents, especially bacteria and viruses, account for a vast number of hospitalisations and mortality worldwide. Providing effective and timely diagnostics for the multiplicity of infectious diseases is challenging. Conventional diagnostic solutions, although technologically advanced, are highly complex and often inaccessible in resource-limited [...] Read more.

Infectious agents, especially bacteria and viruses, account for a vast number of hospitalisations and mortality worldwide. Providing effective and timely diagnostics for the multiplicity of infectious diseases is challenging. Conventional diagnostic solutions, although technologically advanced, are highly complex and often inaccessible in resource-limited settings. An alternative strategy involves convenient rapid diagnostics which can be easily administered at the point-of-care (POC) and at low cost without sacrificing reliability. Biosensors and other rapid POC diagnostic tools which require biorecognition elements to precisely identify the causative pathogen are being developed. The effectiveness of these devices is highly dependent on their biorecognition capabilities. Naturally occurring biorecognition elements include antibodies, bacteriophages and enzymes. Recently, modified molecules such as DNAzymes, peptide nucleic acids and molecules which suffer a selective screening like aptamers and peptides are gaining interest for their biorecognition capabilities and other advantages over purely natural ones, such as robustness and lower production costs. Antimicrobials with a broad-spectrum activity against pathogens, such as antibiotics, are also used in dual diagnostic and therapeutic strategies. Other successful pathogen identification strategies use chemical ligands, molecularly imprinted polymers and Clustered Regularly Interspaced Short Palindromic Repeats-associated nuclease. Herein, the latest developments regarding biorecognition elements and strategies to use them in the design of new biosensors for pathogens detection are reviewed. Full article

(This article belongs to the Special Issue Biosensors for Diagnosis and Monitoring)

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30 pages, 8763 KiB

Open AccessReview

Rolling Circle Amplification as an Efficient Analytical Tool for Rapid Detection of Contaminants in Aqueous Environments

by Kuankuan Zhang, Hua Zhang, Haorui Cao, Yu Jiang, Kang Mao and Zhugen Yang

Biosensors 2021, 11(10), 352; https://doi.org/10.3390/bios11100352 - 23 Sep 2021

Cited by 22 | Viewed by 6977

Abstract

Environmental contaminants are a global concern, and an effective strategy for remediation is to develop a rapid, on-site, and affordable monitoring method. However, this remains challenging, especially with regard to the detection of various contaminants in complex water environments. The application of molecular [...] Read more.

Environmental contaminants are a global concern, and an effective strategy for remediation is to develop a rapid, on-site, and affordable monitoring method. However, this remains challenging, especially with regard to the detection of various contaminants in complex water environments. The application of molecular methods has recently attracted increasing attention; for example, rolling circle amplification (RCA) is an isothermal enzymatic process in which a short nucleic acid primer is amplified to form a long single-stranded nucleic acid using a circular template and special nucleic acid polymerases. Furthermore, this approach can be further engineered into a device for point-of-need monitoring of environmental pollutants. In this paper, we describe the fundamental principles of RCA and the advantages and disadvantages of RCA assays. Then, we discuss the recently developed RCA-based tools for environmental analysis to determine various targets, including heavy metals, organic small molecules, nucleic acids, peptides, proteins, and even microorganisms in aqueous environments. Finally, we summarize the challenges and outline strategies for the advancement of this technique for application in contaminant monitoring. Full article

(This article belongs to the Special Issue Biosensors for Diagnosis and Monitoring)

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21 pages, 5544 KiB

Open AccessEditor’s ChoiceReview

Wearable Biosensors for Non-Invasive Sweat Diagnostics

by Jing Xu, Yunsheng Fang and Jun Chen

Biosensors 2021, 11(8), 245; https://doi.org/10.3390/bios11080245 - 23 Jul 2021

Cited by 103 | Viewed by 20928

Abstract

Recent advances in microfluidics, microelectronics, and electrochemical sensing methods have steered the way for the development of novel and potential wearable biosensors for healthcare monitoring. Wearable bioelectronics has received tremendous attention worldwide due to its great a potential for predictive medical modeling and [...] Read more.

Recent advances in microfluidics, microelectronics, and electrochemical sensing methods have steered the way for the development of novel and potential wearable biosensors for healthcare monitoring. Wearable bioelectronics has received tremendous attention worldwide due to its great a potential for predictive medical modeling and allowing for personalized point-of-care-testing (POCT). They possess many appealing characteristics, for example, lightweight, flexibility, good stretchability, conformability, and low cost. These characteristics make wearable bioelectronics a promising platform for personalized devices. In this paper, we review recent progress in flexible and wearable sensors for non-invasive biomonitoring using sweat as the bio-fluid. Real-time and molecular-level monitoring of personal health states can be achieved with sweat-based or perspiration-based wearable biosensors. The suitability of sweat and its potential in healthcare monitoring, sweat extraction, and the challenges encountered in sweat-based analysis are summarized. The paper also discusses challenges that still hinder the full-fledged development of sweat-based wearables and presents the areas of future research. Full article

(This article belongs to the Special Issue Biosensors for Diagnosis and Monitoring)

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30 pages, 10163 KiB

Open AccessReview

Electromagnetic Torso Scanning: A Review of Devices, Algorithms, and Systems

by Sasan Ahdi Rezaeieh, Amin Darvazehban, Azin S. Janani and Amin M. Abbosh

Biosensors 2021, 11(5), 135; https://doi.org/10.3390/bios11050135 - 27 Apr 2021

Cited by 18 | Viewed by 3682

Abstract

The past decade has witnessed a surge into research on disruptive technologies that either challenge or complement conventional thoracic diagnostic modalities. The non-ionizing, non-invasive, compact, and low power requirements of electromagnetic (EM) techniques make them among the top contenders with varieties of proposed [...] Read more.

The past decade has witnessed a surge into research on disruptive technologies that either challenge or complement conventional thoracic diagnostic modalities. The non-ionizing, non-invasive, compact, and low power requirements of electromagnetic (EM) techniques make them among the top contenders with varieties of proposed scanning systems, which can be used to detect wide range of thoracic illnesses. Different configurations, antenna topologies and detection or imaging algorithms are utilized in these systems. Hence, to appreciate their progress and assess their potential, a critical review of EM thoracic scanning systems is presented. Considering the numerous thoracic diseases, such as fatty liver disease, lung cancer, respiratory and heart related complications, this paper will exclusively focus on torso scanning systems, tracing the early foundation of research that studied the possibility of using EM waves to detect thoracic diseases besides exploring recent progresses. The advantages and disadvantages of proposed systems and future possibilities are thoroughly discussed. Full article

(This article belongs to the Special Issue Biosensors for Diagnosis and Monitoring)

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32 pages, 6319 KiB

Open AccessReview

Fiber Optic Sensors for Vital Signs Monitoring. A Review of Its Practicality in the Health Field

by Christian Perezcampos Mayoral, Jaime Gutiérrez Gutiérrez, José Luis Cano Pérez, Marciano Vargas Treviño, Itandehui Belem Gallegos Velasco, Pedro António Hernández Cruz, Rafael Torres Rosas, Lorenzo Tepech Carrillo, Judith Arnaud Ríos, Edmundo López Apreza and Roberto Rojas Laguna

Biosensors 2021, 11(2), 58; https://doi.org/10.3390/bios11020058 - 23 Feb 2021

Cited by 38 | Viewed by 6197

Abstract

Vital signs not only reflect essential functions of the human body but also symptoms of a more serious problem within the anatomy; they are well used for physical monitoring, caloric expenditure, and performance before a possible symptom of a massive failure—a great variety [...] Read more.

Vital signs not only reflect essential functions of the human body but also symptoms of a more serious problem within the anatomy; they are well used for physical monitoring, caloric expenditure, and performance before a possible symptom of a massive failure—a great variety of possibilities that together form a first line of basic diagnosis and follow-up on the health and general condition of a person. This review includes a brief theory about fiber optic sensors’ operation and summarizes many research works carried out with them in which their operation and effectiveness are promoted to register some vital sign(s) as a possibility for their use in the medical, health care, and life support fields. The review presents methods and techniques to improve sensitivity in monitoring vital signs, such as the use of doping agents or coatings for optical fiber (OF) that provide stability and resistance to the external factors from which they must be protected in in vivo situations. It has been observed that most of these sensors work with single-mode optical fibers (SMF) in a spectral range of 1550 nm, while only some work in the visible spectrum (Vis); the vast majority, operate through fiber Bragg gratings (FBG), long-period fiber gratings (LPFG), and interferometers. These sensors have brought great advances to the measurement of vital signs, especially with regard to respiratory rate; however, many express the possibility of monitoring other vital signs through mathematical calculations, algorithms, or auxiliary devices. Their advantages due to miniaturization, immunity to electromagnetic interference, and the absence of a power source makes them truly desirable for everyday use at all times. Full article

(This article belongs to the Special Issue Biosensors for Diagnosis and Monitoring)

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Other

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12 pages, 1191 KiB

Open AccessPerspective

Point-of-Care PCR Assays for COVID-19 Detection

by Niharika Gupta, Shine Augustine, Tarun Narayan, Alan O’Riordan, Asmita Das, D. Kumar, John H. T. Luong and Bansi D. Malhotra

Biosensors 2021, 11(5), 141; https://doi.org/10.3390/bios11050141 - 1 May 2021

Cited by 81 | Viewed by 14657

Abstract

Molecular diagnostics has been the front runner in the world’s response to the COVID-19 pandemic. Particularly, reverse transcriptase-polymerase chain reaction (RT-PCR) and the quantitative variant (qRT-PCR) have been the gold standard for COVID-19 diagnosis. However, faster antigen tests and other point-of-care (POC) devices [...] Read more.

Molecular diagnostics has been the front runner in the world’s response to the COVID-19 pandemic. Particularly, reverse transcriptase-polymerase chain reaction (RT-PCR) and the quantitative variant (qRT-PCR) have been the gold standard for COVID-19 diagnosis. However, faster antigen tests and other point-of-care (POC) devices have also played a significant role in containing the spread of SARS-CoV-2 by facilitating mass screening and delivering results in less time. Thus, despite the higher sensitivity and specificity of the RT-PCR assays, the impact of POC tests cannot be ignored. As a consequence, there has been an increased interest in the development of miniaturized, high-throughput, and automated PCR systems, many of which can be used at point-of-care. This review summarizes the recent advances in the development of miniaturized PCR systems with an emphasis on COVID-19 detection. The distinct features of digital PCR and electrochemical PCR are detailed along with the challenges. The potential of CRISPR/Cas technology for POC diagnostics is also highlighted. Commercial RT–PCR POC systems approved by various agencies for COVID-19 detection are discussed. Full article

(This article belongs to the Special Issue Biosensors for Diagnosis and Monitoring)

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