Editor’s Choice Articles

Editor’s Choice articles are based on recommendations by the scientific editors of MDPI journals from around the world. Editors select a small number of articles recently published in the journal that they believe will be particularly interesting to readers, or important in the respective research area. The aim is to provide a snapshot of some of the most exciting work published in the various research areas of the journal.

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27 pages, 6797 KiB  
Review
Applications of Optical Fiber in Label-Free Biosensors and Bioimaging: A Review
by Baocheng Li, Ruochong Zhang, Renzhe Bi and Malini Olivo
Biosensors 2023, 13(1), 64; https://doi.org/10.3390/bios13010064 - 30 Dec 2022
Cited by 8 | Viewed by 2950
Abstract
Biosensing and bioimaging are essential in understanding biological and pathological processes in a living system, for example, in detecting and understanding certain diseases. Optical fiber has made remarkable contributions to the biosensing and bioimaging areas due to its unique advantages of compact size, [...] Read more.
Biosensing and bioimaging are essential in understanding biological and pathological processes in a living system, for example, in detecting and understanding certain diseases. Optical fiber has made remarkable contributions to the biosensing and bioimaging areas due to its unique advantages of compact size, immunity to electromagnetic interference, biocompatibility, fast response, etc. This review paper will present an overview of seven common types of optical fiber biosensors and optical fiber-based ultrasound detection in photoacoustic imaging (PAI) and the applications of these technologies in biosensing and bioimaging areas. Of course, there are many types of optical fiber biosensors. Still, this paper will review the most common ones: optical fiber grating, surface plasmon resonance, Sagnac interferometer, Mach–Zehnder interferometer, Michelson interferometer, Fabry–Perot Interferometer, lossy mode resonance, and surface-enhanced Raman scattering. Furthermore, different optical fiber techniques for detecting ultrasound in PAI are summarized. Finally, the main challenges and future development direction are briefly discussed. Full article
(This article belongs to the Special Issue Emerging Applications of Label-Free Optical Biosensors)
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27 pages, 3529 KiB  
Review
Microfluidic Strategies for Extracellular Vesicle Isolation: Towards Clinical Applications
by Alessio Meggiolaro, Valentina Moccia, Paola Brun, Matteo Pierno, Giampaolo Mistura, Valentina Zappulli and Davide Ferraro
Biosensors 2023, 13(1), 50; https://doi.org/10.3390/bios13010050 - 29 Dec 2022
Cited by 13 | Viewed by 3498
Abstract
Extracellular vesicles (EVs) are double-layered lipid membrane vesicles released by cells. Currently, EVs are attracting a lot of attention in the biological and medical fields due to their role as natural carriers of proteins, lipids, and nucleic acids. Thus, they can transport useful [...] Read more.
Extracellular vesicles (EVs) are double-layered lipid membrane vesicles released by cells. Currently, EVs are attracting a lot of attention in the biological and medical fields due to their role as natural carriers of proteins, lipids, and nucleic acids. Thus, they can transport useful genomic information from their parental cell through body fluids, promoting cell-to-cell communication even between different organs. Due to their functionality as cargo carriers and their protein expression, they can play an important role as possible diagnostic and prognostic biomarkers in various types of diseases, e.g., cancers, neurodegenerative, and autoimmune diseases. Today, given the invaluable importance of EVs, there are some pivotal challenges to overcome in terms of their isolation. Conventional methods have some limitations: they are influenced by the starting sample, might present low throughput and low purity, and sometimes a lack of reproducibility, being operator dependent. During the past few years, several microfluidic approaches have been proposed to address these issues. In this review, we summarize the most important microfluidic-based devices for EV isolation, highlighting their advantages and disadvantages compared to existing technology, as well as the current state of the art from the perspective of the use of these devices in clinical applications. Full article
(This article belongs to the Special Issue Microfluidics for Biomedical Applications)
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21 pages, 2988 KiB  
Review
Analyte Sensing with Catalytic Micromotors
by Mihail N. Popescu and Szilveszter Gáspár
Biosensors 2023, 13(1), 45; https://doi.org/10.3390/bios13010045 - 28 Dec 2022
Cited by 4 | Viewed by 1857
Abstract
Catalytic micromotors can be used to detect molecules of interest in several ways. The straightforward approach is to use such motors as sensors of their “fuel” (i.e., of the species consumed for self-propulsion). Another way is in the detection of species which are [...] Read more.
Catalytic micromotors can be used to detect molecules of interest in several ways. The straightforward approach is to use such motors as sensors of their “fuel” (i.e., of the species consumed for self-propulsion). Another way is in the detection of species which are not fuel but still modulate the catalytic processes facilitating self-propulsion. Both of these require analysis of the motion of the micromotors because the speed (or the diffusion coefficient) of the micromotors is the analytical signal. Alternatively, catalytic micromotors can be used as the means to enhance mass transport, and thus increase the probability of specific recognition events in the sample. This latter approach is based on “classic” (e.g., electrochemical) analytical signals and does not require an analysis of the motion of the micromotors. Together with a discussion of the current limitations faced by sensing concepts based on the speed (or diffusion coefficient) of catalytic micromotors, we review the findings of the studies devoted to the analytical performances of catalytic micromotor sensors. We conclude that the qualitative (rather than quantitative) analysis of small samples, in resource poor environments, is the most promising niche for the catalytic micromotors in analytical chemistry. Full article
(This article belongs to the Special Issue Feature Issue of Biosensors and Bioelectronic Devices Section)
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22 pages, 2844 KiB  
Review
Review on the Selection of Aptamers and Application in Paper-Based Sensors
by Kaifei Wang, Minglu Wang, Teng Ma, Wenyu Li and Hongyan Zhang
Biosensors 2023, 13(1), 39; https://doi.org/10.3390/bios13010039 - 27 Dec 2022
Cited by 19 | Viewed by 4091
Abstract
An aptamer is a synthetic oligonucleotide, referring to a single-stranded deoxyribonucleic acid or ribonucleic acid ligand produced by synthesis from outside the body using systematic evolution of ligands by exponential enrichment (SELEX) technology. Owing to their special screening process and adjustable tertiary structures, [...] Read more.
An aptamer is a synthetic oligonucleotide, referring to a single-stranded deoxyribonucleic acid or ribonucleic acid ligand produced by synthesis from outside the body using systematic evolution of ligands by exponential enrichment (SELEX) technology. Owing to their special screening process and adjustable tertiary structures, aptamers can bind to multiple targets (small molecules, proteins, and even whole cells) with high specificity and affinity. Moreover, due to their simple preparation and stable modification, they have been widely used to construct biosensors for target detection. The paper-based sensor is a product with a low price, short detection time, simple operation, and other superior characteristics, and is widely used as a rapid detection method. This review mainly focuses on the screening methods of aptamers, paper-based devices, and applicable sensing strategies. Furthermore, the design of the aptamer-based lateral flow assay (LFA), which underlies the most promising devices for commercialization, is emphasized. In addition, the development prospects and potential applications of paper-based biosensors using aptamers as recognition molecules are also discussed. Full article
(This article belongs to the Special Issue Paper-Based Biosensors)
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9 pages, 1214 KiB  
Article
Shape-Programmable Liquid Metal Fibers
by Biao Ma, Jin Zhang, Gangsheng Chen, Yi Chen, Chengtao Xu, Lanjie Lei and Hong Liu
Biosensors 2023, 13(1), 28; https://doi.org/10.3390/bios13010028 - 26 Dec 2022
Cited by 8 | Viewed by 2831
Abstract
Conductive and stretchable fibers are the cornerstone of intelligent textiles and imperceptible electronics. Among existing fiber conductors, gallium-based liquid metals (LMs) featuring high conductivity, fluidity, and self-healing are excellent candidates for highly stretchable fibers with sensing, actuation, power generation, and interconnection functionalities. However, [...] Read more.
Conductive and stretchable fibers are the cornerstone of intelligent textiles and imperceptible electronics. Among existing fiber conductors, gallium-based liquid metals (LMs) featuring high conductivity, fluidity, and self-healing are excellent candidates for highly stretchable fibers with sensing, actuation, power generation, and interconnection functionalities. However, current LM fibers fabricated by direct injection or surface coating have a limitation in shape programmability. This hinders their applications in functional fibers with tunable electromechanical response and miniaturization. Here, we reported a simple and efficient method to create shape-programmable LM fibers using the phase transition of gallium. Gallium metal wires in the solid state can be easily shaped into a 3D helical structure, and the structure can be preserved after coating the wire with polyurethane and liquifying the metal. The 3D helical LM fiber offered enhanced stretchability with a high breaking strain of 1273% and showed invariable conductance over 283% strain. Moreover, we can reduce the fiber diameter by stretching the fiber during the solidification of polyurethane. We also demonstrated applications of the programmed fibers in self-powered strain sensing, heart rate monitoring, airflow, and humidity sensing. This work provided simple and facile ways toward functional LM fibers, which may facilitate the broad applications of LM fibers in e-skins, wearable computation, soft robots, and smart fabrics. Full article
(This article belongs to the Special Issue Liquid Metal Based Biosensors and Bioelectronic Devices)
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22 pages, 3240 KiB  
Review
Recent Advances in Colorimetric Sensors Based on Gold Nanoparticles for Pathogen Detection
by Jianyu Yang, Xin Wang, Yuyang Sun, Bo Chen, Fangxin Hu, Chunxian Guo and Ting Yang
Biosensors 2023, 13(1), 29; https://doi.org/10.3390/bios13010029 - 26 Dec 2022
Cited by 20 | Viewed by 6130
Abstract
Infectious pathogens cause severe threats to public health due to their frightening infectivity and lethal capacity. Rapid and accurate detection of pathogens is of great significance for preventing their infection. Gold nanoparticles have drawn considerable attention in colorimetric biosensing during the past decades [...] Read more.
Infectious pathogens cause severe threats to public health due to their frightening infectivity and lethal capacity. Rapid and accurate detection of pathogens is of great significance for preventing their infection. Gold nanoparticles have drawn considerable attention in colorimetric biosensing during the past decades due to their unique physicochemical properties. Colorimetric diagnosis platforms based on functionalized AuNPs are emerging as a promising pathogen-analysis technique with the merits of high sensitivity, low-cost, and easy operation. This review summarizes the recent development in this field. We first introduce the significance of detecting pathogens and the characteristics of gold nanoparticles. Four types of colorimetric strategies, including the application of indirect target-mediated aggregation, chromogenic substrate-mediated catalytic activity, point-of-care testing (POCT) devices, and machine learning-assisted colorimetric sensor arrays, are systematically introduced. In particular, three biomolecule-functionalized AuNP-based colorimetric sensors are described in detail. Finally, we conclude by presenting our subjective views on the present challenges and some appropriate suggestions for future research directions of colorimetric sensors. Full article
(This article belongs to the Section Biosensor Materials)
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22 pages, 3754 KiB  
Review
State-of-the-Art Fluorescent Probes: Duplex-Specific Nuclease-Based Strategies for Early Disease Diagnostics
by Ghazala Ashraf, Zi-Tao Zhong, Muhammad Asif, Ayesha Aziz, Tayyaba Iftikhar, Wei Chen and Yuan-Di Zhao
Biosensors 2022, 12(12), 1172; https://doi.org/10.3390/bios12121172 - 15 Dec 2022
Cited by 6 | Viewed by 2628
Abstract
Precision healthcare aims to improve patient health by integrating prevention measures with early disease detection for prompt treatments. For the delivery of preventive healthcare, cutting-edge diagnostics that enable early disease detection must be clinically adopted. Duplex-specific nuclease (DSN) is a useful tool for [...] Read more.
Precision healthcare aims to improve patient health by integrating prevention measures with early disease detection for prompt treatments. For the delivery of preventive healthcare, cutting-edge diagnostics that enable early disease detection must be clinically adopted. Duplex-specific nuclease (DSN) is a useful tool for bioanalysis since it can precisely digest DNA contained in duplexes. DSN is commonly used in biomedical and life science applications, including the construction of cDNA libraries, detection of microRNA, and single-nucleotide polymorphism (SNP) recognition. Herein, following the comprehensive introduction to the field, we highlight the clinical applicability, multi-analyte miRNA, and SNP clinical assays for disease diagnosis through large-cohort studies using DSN-based fluorescent methods. In fluorescent platforms, the signal is produced based on the probe (dyes, TaqMan, or molecular beacon) properties in proportion to the target concentration. We outline the reported fluorescent biosensors for SNP detection in the next section. This review aims to capture current knowledge of the overlapping miRNAs and SNPs’ detection that have been widely associated with the pathophysiology of cancer, cardiovascular, neural, and viral diseases. We further highlight the proficiency of DSN-based approaches in complex biological matrices or those constructed on novel nano-architectures. The outlooks on the progress in this field are discussed. Full article
(This article belongs to the Special Issue Advances in Fluorescent Probe Biosensing)
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21 pages, 2678 KiB  
Review
A Review: Research Progress of Neural Probes for Brain Research and Brain–Computer Interface
by Jiahui Luo, Ning Xue and Jiamin Chen
Biosensors 2022, 12(12), 1167; https://doi.org/10.3390/bios12121167 - 14 Dec 2022
Cited by 8 | Viewed by 3229
Abstract
Neural probes, as an invasive physiological tool at the mesoscopic scale, can decipher the code of brain connections and communications from the cellular or even molecular level, and realize information fusion between the human body and external machines. In addition to traditional electrodes, [...] Read more.
Neural probes, as an invasive physiological tool at the mesoscopic scale, can decipher the code of brain connections and communications from the cellular or even molecular level, and realize information fusion between the human body and external machines. In addition to traditional electrodes, two new types of neural probes have been developed in recent years: optoprobes based on optogenetics and magnetrodes that record neural magnetic signals. In this review, we give a comprehensive overview of these three kinds of neural probes. We firstly discuss the development of microelectrodes and strategies for their flexibility, which is mainly represented by the selection of flexible substrates and new electrode materials. Subsequently, the concept of optogenetics is introduced, followed by the review of several novel structures of optoprobes, which are divided into multifunctional optoprobes integrated with microfluidic channels, artifact-free optoprobes, three-dimensional drivable optoprobes, and flexible optoprobes. At last, we introduce the fundamental perspectives of magnetoresistive (MR) sensors and then review the research progress of magnetrodes based on it. Full article
(This article belongs to the Section Biosensor and Bioelectronic Devices)
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25 pages, 7793 KiB  
Review
Bioprinting on Organ-on-Chip: Development and Applications
by Maria Anna Chliara, Stavroula Elezoglou and Ioanna Zergioti
Biosensors 2022, 12(12), 1135; https://doi.org/10.3390/bios12121135 - 6 Dec 2022
Cited by 13 | Viewed by 4444
Abstract
Organs-on-chips (OoCs) are microfluidic devices that contain bioengineered tissues or parts of natural tissues or organs and can mimic the crucial structures and functions of living organisms. They are designed to control and maintain the cell- and tissue-specific microenvironment while also providing detailed [...] Read more.
Organs-on-chips (OoCs) are microfluidic devices that contain bioengineered tissues or parts of natural tissues or organs and can mimic the crucial structures and functions of living organisms. They are designed to control and maintain the cell- and tissue-specific microenvironment while also providing detailed feedback about the activities that are taking place. Bioprinting is an emerging technology for constructing artificial tissues or organ constructs by combining state-of-the-art 3D printing methods with biomaterials. The utilization of 3D bioprinting and cells patterning in OoC technologies reinforces the creation of more complex structures that can imitate the functions of a living organism in a more precise way. Here, we summarize the current 3D bioprinting techniques and we focus on the advantages of 3D bioprinting compared to traditional cell seeding in addition to the methods, materials, and applications of 3D bioprinting in the development of OoC microsystems. Full article
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19 pages, 3203 KiB  
Review
Detection of Emerging Pollutants Using Aptamer-Based Biosensors: Recent Advances, Challenges, and Outlook
by Elda A. Flores-Contreras, Reyna Berenice González-González, Everardo González-González, Elda M. Melchor-Martínez, Roberto Parra-Saldívar and Hafiz M. N. Iqbal
Biosensors 2022, 12(12), 1078; https://doi.org/10.3390/bios12121078 - 25 Nov 2022
Cited by 6 | Viewed by 3017
Abstract
The synergistic potentialities of innovative materials that include aptamers have opened new paradigms in biosensing platforms for high-throughput monitoring systems. The available nucleobase functional moieties in aptamers offer exclusive features for bioanalytical sensing applications. In this context, compared to various in-practice biological recognition [...] Read more.
The synergistic potentialities of innovative materials that include aptamers have opened new paradigms in biosensing platforms for high-throughput monitoring systems. The available nucleobase functional moieties in aptamers offer exclusive features for bioanalytical sensing applications. In this context, compared to various in-practice biological recognition elements, the utilization of aptamers in detection platforms results in an extensive range of advantages in terms of design flexibility, stability, and sensitivity, among other attributes. Thus, the utilization of aptamers-based biosensing platforms is extensively anticipated to meet unaddressed challenges of various in-practice and standard analytical and sensing techniques. Furthermore, the superior characteristics of aptasensors have led to their applicability in the detection of harmful pollutants present in ever-increasing concentrations in different environmental matrices and water bodies, seeking to achieve simple and real-time monitoring. Considering the above-mentioned critiques and notable functional attributes of aptamers, herein, we reviewed aptamers as a fascinating interface to design, develop, and deploy a new generation of monitoring systems to aid modern bioanalytical sensing applications. Moreover, this review aims to summarize the most recent advances in the development and application of aptasensors for the detection of various emerging pollutants (EPs), e.g., pharmaceutical, and personal care products (PPCPs), endocrine-disrupting chemicals (EDCs), pesticides and other agricultural-related compounds, and toxic heavy elements. In addition, the limitations and current challenges are also reviewed, considering the technical constraints and complexity of the environmental samples. Full article
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43 pages, 2817 KiB  
Review
Potential Environmental and Health Implications from the Scaled-Up Production and Disposal of Nanomaterials Used in Biosensors
by Kelli M. McCourt, Jarad Cochran, Sabah M. Abdelbasir, Elizabeth R. Carraway, Tzuen-Rong J. Tzeng, Olga V. Tsyusko and Diana C. Vanegas
Biosensors 2022, 12(12), 1082; https://doi.org/10.3390/bios12121082 - 25 Nov 2022
Cited by 5 | Viewed by 2739
Abstract
Biosensors often combine biological recognition elements with nanomaterials of varying compositions and dimensions to facilitate or enhance the operating mechanism of the device. While incorporating nanomaterials is beneficial to developing high-performance biosensors, at the stages of scale-up and disposal, it may lead to [...] Read more.
Biosensors often combine biological recognition elements with nanomaterials of varying compositions and dimensions to facilitate or enhance the operating mechanism of the device. While incorporating nanomaterials is beneficial to developing high-performance biosensors, at the stages of scale-up and disposal, it may lead to the unmanaged release of toxic nanomaterials. Here we attempt to foster connections between the domains of biosensors development and human and environmental toxicology to encourage a holistic approach to the development and scale-up of biosensors. We begin by exploring the toxicity of nanomaterials commonly used in biosensor design. From our analysis, we introduce five factors with a role in nanotoxicity that should be considered at the biosensor development stages to better manage toxicity. Finally, we contextualize the discussion by presenting the relevant stages and routes of exposure in the biosensor life cycle. Our review found little consensus on how the factors presented govern nanomaterial toxicity, especially in composite and alloyed nanomaterials. To bridge the current gap in understanding and mitigate the risks of uncontrolled nanomaterial release, we advocate for greater collaboration through a precautionary One Health approach to future development and a movement towards a circular approach to biosensor use and disposal. Full article
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12 pages, 15924 KiB  
Article
On-Chip Single-Cell Bioelectrical Analysis for Identification of Cell Electrical Phenotyping in Response to Sequential Electric Signal Modulation
by Seungyeop Choi, Insu Park, Sang Hyun Lee, Kang In Yeo, Gyeongjun Min, Sung-Hun Woo, Yoon Suk Kim, Sei Young Lee and Sang Woo Lee
Biosensors 2022, 12(11), 1037; https://doi.org/10.3390/bios12111037 - 17 Nov 2022
Cited by 1 | Viewed by 1684
Abstract
In recent years, an interesting biomarker called membrane breakdown voltage has been examined using artificial planar lipid bilayers. Even though they have great potential to identify cell electrical phenotyping for distinguishing similar cell lines or cells under different physiological conditions, the biomarker has [...] Read more.
In recent years, an interesting biomarker called membrane breakdown voltage has been examined using artificial planar lipid bilayers. Even though they have great potential to identify cell electrical phenotyping for distinguishing similar cell lines or cells under different physiological conditions, the biomarker has not been evaluated in the context of living cell electrical phenotyping. Herein, we present a single-cell analysis platform to continuously measure the electric response in a large number of cells in parallel using electric frequency and voltage variables. Using this platform, we measured the direction of cell displacement and transparent cell image alteration as electric polarization of the cell responds to signal modulation, extracting the dielectrophoretic crossover frequency and membrane breakdown voltage for each cell, and utilizing the measurement results in the same spatiotemporal environment. We developed paired parameters using the dielectrophoretic crossover frequency and membrane breakdown voltage for each cell and evaluated the paired parameter efficiency concerning the identification of two different breast cancer cells and cell drug response. Moreover, we showed that the platform was able to identify cell electrical phenotyping, which was generated by subtle changes in cholesterol depletion-induced cell membrane integrity disruption when the paired parameter was used. Our platform introduced in this paper is extremely useful for facilitating more accurate and efficient evaluation of cell electrical phenotyping in a variety of applications, such as cell biology and drug discovery. Full article
(This article belongs to the Section Biosensor and Bioelectronic Devices)
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12 pages, 2196 KiB  
Article
Sample-to-Answer Immuno-Magnetic Assay Using Thermally Responsive Alkane Partitions
by Micaela L. Everitt, David J. Boegner and Ian M. White
Biosensors 2022, 12(11), 1030; https://doi.org/10.3390/bios12111030 - 17 Nov 2022
Viewed by 2047
Abstract
To combat pandemics, there is a need for rapid point-of-care diagnostics to identify infected patients and to track the spread of the disease. While recent progress has been made in response to COVID-19, there continues to be a need for point-of-care diagnostics capable [...] Read more.
To combat pandemics, there is a need for rapid point-of-care diagnostics to identify infected patients and to track the spread of the disease. While recent progress has been made in response to COVID-19, there continues to be a need for point-of-care diagnostics capable of detecting biomarkers—such as antibodies—in whole blood. We have recently reported the development of thermally responsive alkane partitions (TRAPs) for the automation of point-of-care immuno-magnetic assays. Here, we demonstrate the use of TRAPs to enable sample-to-answer detection of antibodies against the SARS-CoV-2 virus in whole blood samples. We report a limit of detection of 84 pg/mL, well below the clinically relevant threshold. We anticipate that the TRAP-enabled sample-to-answer immunoassay can be used to track the progression of future pandemics, leading to a more informed and robust clinical and societal response. Full article
(This article belongs to the Section Biosensors and Healthcare)
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25 pages, 5516 KiB  
Review
Review of Electrochemical Biosensors for Food Safety Detection
by Ke Wang, Xiaogang Lin, Maoxiao Zhang, Yu Li, Chunfeng Luo and Jayne Wu
Biosensors 2022, 12(11), 959; https://doi.org/10.3390/bios12110959 - 2 Nov 2022
Cited by 36 | Viewed by 6822
Abstract
Food safety issues are directly related to people’s quality of life, so there is a need to develop efficient and reliable food contaminants’ detection devices to ensure the safety and quality of food. Electrochemical biosensors have the significant advantages of miniaturization, low cost, [...] Read more.
Food safety issues are directly related to people’s quality of life, so there is a need to develop efficient and reliable food contaminants’ detection devices to ensure the safety and quality of food. Electrochemical biosensors have the significant advantages of miniaturization, low cost, high sensitivity, high selectivity, rapid detection, and low detection limits using small amounts of samples, which are expected to enable on-site analysis of food products. In this paper, the latest electrochemical biosensors for the detection of biological contaminants, chemical contaminants, and genetically modified crops are reviewed based on the analytes of interest, electrode materials and modification methods, electrochemical methods, and detection limits. This review shows that electrochemical biosensors are poised to provide miniaturized, specific, selective, fast detection, and high-sensitivity sensor platforms for food safety. Full article
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19 pages, 3085 KiB  
Review
Gold-Nanoparticle-Based Chiral Plasmonic Nanostructures and Their Biomedical Applications
by Hanbo Li, Xinshuang Gao, Chenqi Zhang, Yinglu Ji, Zhijian Hu and Xiaochun Wu
Biosensors 2022, 12(11), 957; https://doi.org/10.3390/bios12110957 - 1 Nov 2022
Cited by 13 | Viewed by 4283
Abstract
As chiral antennas, plasmonic nanoparticles (NPs) can enhance chiral responses of chiral materials by forming hybrid structures and improving their own chirality preference as well. Chirality-dependent properties of plasmonic NPs broaden application potentials of chiral nanostructures in the biomedical field. Herein, we review [...] Read more.
As chiral antennas, plasmonic nanoparticles (NPs) can enhance chiral responses of chiral materials by forming hybrid structures and improving their own chirality preference as well. Chirality-dependent properties of plasmonic NPs broaden application potentials of chiral nanostructures in the biomedical field. Herein, we review the wet-chemical synthesis and self-assembly fabrication of gold-NP-based chiral nanostructures. Discrete chiral NPs are mainly obtained via the seed-mediated growth of achiral gold NPs under the guide of chiral molecules during growth. Irradiation with chiral light during growth is demonstrated to be a promising method for chirality control. Chiral assemblies are fabricated via the bottom-up assembly of achiral gold NPs using chiral linkers or guided by chiral templates, which exhibit large chiroplasmonic activities. In describing recent advances, emphasis is placed on the design and synthesis of chiral nanostructures with the tuning and amplification of plasmonic circular dichroism responses. In addition, the review discusses the most recent or even emerging trends in biomedical fields from biosensing and imaging to disease diagnosis and therapy. Full article
(This article belongs to the Section Biosensors and Healthcare)
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11 pages, 2046 KiB  
Article
A Flexible Optoelectronic Device for Continuous Cerebral Blood Flow Monitoring
by Huawei Ji, Ze Xu, Mingyu Wang, Hong Zou, Ying Chen and Jun Ai
Biosensors 2022, 12(11), 944; https://doi.org/10.3390/bios12110944 - 31 Oct 2022
Viewed by 1561
Abstract
Human cerebral oxygenation and hemodynamics can be estimated by cerebral oxygenation parameters. Functional near-infrared spectroscopy (fNIRS) can be used to measure the hemoglobin concentration index of brain tissue noninvasively and in real time. However, limited by cumbersome equipment, high price and uncomfortable wear, [...] Read more.
Human cerebral oxygenation and hemodynamics can be estimated by cerebral oxygenation parameters. Functional near-infrared spectroscopy (fNIRS) can be used to measure the hemoglobin concentration index of brain tissue noninvasively and in real time. However, limited by cumbersome equipment, high price and uncomfortable wear, conventional fNIRS monitoring systems still cannot achieve continuous and long-term monitoring. In this work, a flexible and wearable long-term monitoring system is developed featured with cost efficiency, simple preparation and light weight (only 1.6 g), which consists of a pair of light-emitting diodes (LEDs) and a photodetector (PD). Triangular serpentine interconnectors are introduced to connect the functional elements, enabling the device to be stretched in multiple directions. The device can continuously work for 7 h and be subjected to 2000 cycles of bending loading, with less than 3% change in voltage value, 1.89% and 1.9% change in LED luminous power and 0.9% change in voltage value. Furthermore, the hand-gripping and breath-holding experiments show that the system can accurately measure the changes in hemoglobin concentration in accordance with the commercial device. The flexible fNIRS system presented here not only provides a simple preparation process but also offers new ideas for daily cerebral state monitoring and prolonged clinical monitoring. Full article
(This article belongs to the Section Biosensor and Bioelectronic Devices)
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13 pages, 2157 KiB  
Article
A Portable Smartphone-Based System for the Detection of Blood Calcium Using Ratiometric Fluorescent Probes
by Yue Wu, Yunshan Zhang, Zhongyuan Xu, Xinyu Guo, Wenjian Yang, Xiaoyu Zhang, Yuheng Liao, Minzhi Fan and Diming Zhang
Biosensors 2022, 12(11), 917; https://doi.org/10.3390/bios12110917 - 24 Oct 2022
Cited by 4 | Viewed by 2571
Abstract
Hypocalcemia is a disease that adversely affects the production and reproduction of dairy cows. A portable device for rapid bovine blood calcium sensing has been growing in demand. Herein, we report a smartphone-based ratiometric fluorescence probe (SRFP) platform as a new way to [...] Read more.
Hypocalcemia is a disease that adversely affects the production and reproduction of dairy cows. A portable device for rapid bovine blood calcium sensing has been growing in demand. Herein, we report a smartphone-based ratiometric fluorescence probe (SRFP) platform as a new way to detect and quantify calcium ions (Ca2+) in blood serum. Specifically, we employed a cost-effective and portable smartphone-based platform coupled with customized software that evaluates the response of Ca2+ ions to ratiometric fluorescence probe in bovine serum. The platform consists of a three-dimensional (3D) printed housing and low-cost optical components that excite fluorescent probe and selectively transmit fluorescence emissions to smartphones. The customized software is equipped with a calibration model to quantify the acquired fluorescence images and quantify the concentration of Ca2+ ions. The ratio of the green channel to the red channel bears a highly reproducible relationship with Ca2+ ions concentration from 10 μM to 40 μM in bovine serum. Our detection system has a limit of detection (LOD) of 1.8 μM in bovine serum samples and the recoveries of real samples ranged from 92.8% to 110.1%, with relative standard deviation (RSD) ranging from 1.72% to 4.89%. The low-cost SRFP platform has the potential to enable campesino to rapidly detect Ca2+ ions content in bovine serum on-demand in any environmental setting. Full article
(This article belongs to the Special Issue Electrical/Optical Biosensing and Regulating Technology)
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22 pages, 2405 KiB  
Review
Bacteriophage-Based Biosensors: A Platform for Detection of Foodborne Bacterial Pathogens from Food and Environment
by Rashad R. Al-Hindi, Addisu D. Teklemariam, Mona G. Alharbi, Ibrahim Alotibi, Sheren A. Azhari, Ishtiaq Qadri, Turki Alamri, Steve Harakeh, Bruce M. Applegate and Arun K. Bhunia
Biosensors 2022, 12(10), 905; https://doi.org/10.3390/bios12100905 - 21 Oct 2022
Cited by 21 | Viewed by 5468
Abstract
Foodborne microorganisms are an important cause of human illness worldwide. Two-thirds of human foodborne diseases are caused by bacterial pathogens throughout the globe, especially in developing nations. Despite enormous developments in conventional foodborne pathogen detection methods, progress is limited by the assay complexity [...] Read more.
Foodborne microorganisms are an important cause of human illness worldwide. Two-thirds of human foodborne diseases are caused by bacterial pathogens throughout the globe, especially in developing nations. Despite enormous developments in conventional foodborne pathogen detection methods, progress is limited by the assay complexity and a prolonged time-to-result. The specificity and sensitivity of assays for live pathogen detection may also depend on the nature of the samples being analyzed and the immunological or molecular reagents used. Bacteriophage-based biosensors offer several benefits, including specificity to their host organism, the detection of only live pathogens, and resistance to extreme environmental factors such as organic solvents, high temperatures, and a wide pH range. Phage-based biosensors are receiving increasing attention owing to their high degree of accuracy, specificity, and reduced assay times. These characteristics, coupled with their abundant supply, make phages a novel bio-recognition molecule in assay development, including biosensors for the detection of foodborne bacterial pathogens to ensure food safety. This review provides comprehensive information about the different types of phage-based biosensor platforms, such as magnetoelastic sensors, quartz crystal microbalance, and electrochemical and surface plasmon resonance for the detection of several foodborne bacterial pathogens from various representative food matrices and environmental samples. Full article
(This article belongs to the Special Issue Microbial Biosensors for Environmental Monitoring)
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20 pages, 5695 KiB  
Review
Electrospinning-Based Biosensors for Health Monitoring
by Guojing Ji, Zhou Chen, Hui Li, Desire Emefa Awuye, Mengdi Guan and Yingbao Zhu
Biosensors 2022, 12(10), 876; https://doi.org/10.3390/bios12100876 - 15 Oct 2022
Cited by 22 | Viewed by 3242
Abstract
In recent years, many different biosensors are being used to monitor physical health. Electrospun nanofiber materials have the advantages of high specific surface area, large porosity and simple operation. These properties play a vital role in biosensors. However, the mechanical properties of electrospun [...] Read more.
In recent years, many different biosensors are being used to monitor physical health. Electrospun nanofiber materials have the advantages of high specific surface area, large porosity and simple operation. These properties play a vital role in biosensors. However, the mechanical properties of electrospun nanofibers are poor relative to other techniques of nanofiber production. At the same time, the organic solvents used in electrospinning are generally toxic and expensive. Meanwhile, the excellent performance of electrospun nanofibers brings about higher levels of sensitivity and detection range of biosensors. This paper summarizes the principle and application of electrospinning technology in biosensors and its comparison with other technologies. Full article
(This article belongs to the Special Issue Nanofiber-Based Biosensors)
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17 pages, 6772 KiB  
Article
Real-Time Monitoring of Breath Biomarkers with A Magnetoelastic Contactless Gas Sensor: A Proof of Concept
by Alvaro Peña, Juan Diego Aguilera, Daniel Matatagui, Patricia de la Presa, Carmen Horrillo, Antonio Hernando and Pilar Marín
Biosensors 2022, 12(10), 871; https://doi.org/10.3390/bios12100871 - 13 Oct 2022
Cited by 6 | Viewed by 2392
Abstract
In the quest for effective gas sensors for breath analysis, magnetoelastic resonance-based gas sensors (MEGSs) are remarkable candidates. Thanks to their intrinsic contactless operation, they can be used as non-invasive and portable devices. However, traditional monitoring techniques are bound to slow detection, which [...] Read more.
In the quest for effective gas sensors for breath analysis, magnetoelastic resonance-based gas sensors (MEGSs) are remarkable candidates. Thanks to their intrinsic contactless operation, they can be used as non-invasive and portable devices. However, traditional monitoring techniques are bound to slow detection, which hinders their application to fast bio-related reactions. Here we present a method for real-time monitoring of the resonance frequency, with a proof of concept for real-time monitoring of gaseous biomarkers based on resonance frequency. This method was validated with a MEGS based on a Metglass 2826 MB microribbon with a polyvinylpyrrolidone (PVP) nanofiber electrospun functionalization. The device provided a low-noise (RMS = 1.7 Hz), fast (<2 min), and highly reproducible response to humidity (Δf = 46–182 Hz for 17–95% RH), ammonia (Δf = 112 Hz for 40 ppm), and acetone (Δf = 44 Hz for 40 ppm). These analytes are highly important in biomedical applications, particularly ammonia and acetone, which are biomarkers related to diseases such as diabetes. Furthermore, the capability of distinguishing between breath and regular air was demonstrated with real breath measurements. The sensor also exhibited strong resistance to benzene, a common gaseous interferent in breath analysis. Full article
(This article belongs to the Special Issue Feature Issue of Biosensors and Bioelectronic Devices Section)
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31 pages, 3336 KiB  
Review
Critical Design Factors for Electrochemical Aptasensors Based on Target-Induced Conformational Changes: The Case of Small-Molecule Targets
by Andra Mihaela Onaş, Constanţa Dascălu, Matei D. Raicopol and Luisa Pilan
Biosensors 2022, 12(10), 816; https://doi.org/10.3390/bios12100816 - 1 Oct 2022
Cited by 16 | Viewed by 3252
Abstract
Nucleic-acid aptamers consisting in single-stranded DNA oligonucleotides emerged as very promising biorecognition elements for electrochemical biosensors applied in various fields such as medicine, environmental, and food safety. Despite their outstanding features, such as high-binding affinity for a broad range of targets, high stability, [...] Read more.
Nucleic-acid aptamers consisting in single-stranded DNA oligonucleotides emerged as very promising biorecognition elements for electrochemical biosensors applied in various fields such as medicine, environmental, and food safety. Despite their outstanding features, such as high-binding affinity for a broad range of targets, high stability, low cost and ease of modification, numerous challenges had to be overcome from the aptamer selection process on the design of functioning biosensing devices. Moreover, in the case of small molecules such as metabolites, toxins, drugs, etc., obtaining efficient binding aptamer sequences proved a challenging task given their small molecular surface and limited interactions between their functional groups and aptamer sequences. Thus, establishing consistent evaluation standards for aptamer affinity is crucial for the success of these aptamers in biosensing applications. In this context, this article will give an overview on the thermodynamic and structural aspects of the aptamer-target interaction, its specificity and selectivity, and will also highlight the current methods employed for determining the aptamer-binding affinity and the structural characterization of the aptamer-target complex. The critical aspects regarding the generation of aptamer-modified electrodes suitable for electrochemical sensing, such as appropriate bioreceptor immobilization strategy and experimental conditions which facilitate a convenient anchoring and stability of the aptamer, are also discussed. The review also summarizes some effective small molecule aptasensing platforms from the recent literature. Full article
(This article belongs to the Special Issue Feature Issue of Nano- and Micro-Technologies in Biosensors Section)
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14 pages, 3732 KiB  
Article
Colorimetric Detection of the SARS-CoV-2 Virus (COVID-19) in Artificial Saliva Using Polydiacetylene Paper Strips
by Christopher D. Prainito, Gaddi Eshun, Francis J. Osonga, Daniel Isika, Cynthia Centeno and Omowunmi A. Sadik
Biosensors 2022, 12(10), 804; https://doi.org/10.3390/bios12100804 - 29 Sep 2022
Cited by 12 | Viewed by 3326
Abstract
The spread and resurgence of the SARS-CoV-2 virus (COVID-19 disease) threatens human health and social relations. Prevention of COVID-19 disease partly relies on fabricating low-cost, point-of-care (POC) sensing technology that can rapidly and selectively detect the SARS-CoV-2 virus. We report a colorimetric, paper-based [...] Read more.
The spread and resurgence of the SARS-CoV-2 virus (COVID-19 disease) threatens human health and social relations. Prevention of COVID-19 disease partly relies on fabricating low-cost, point-of-care (POC) sensing technology that can rapidly and selectively detect the SARS-CoV-2 virus. We report a colorimetric, paper-based polydiacetylene (PDA) biosensor, designed to detect SARS-CoV-2 spike protein in artificial saliva. Analytical characterizations of the PDA sensor using NMR and FT-IR spectroscopy showed the correct structural elucidation of PCDA-NHS conjugation. The PDA sensor platform containing the N-Hydroxysuccinimide ester of 10, 12-pentacosadiynoic acid (PCDA-NHS) was divided into three experimental PCDA-NHS concentration groups of 10%, 20%, and 30% to optimize the performance of the sensor. The optimal PCDA-NHS molar concentration was determined to be 10%. The PDA sensor works by a color change from blue to red as its colorimetric output when the immobilized antibody binds to the SARS-CoV-2 spike protein in saliva samples. Our results showed that the PDA sensing platform was able to rapidly and qualitatively detect the SARS-CoV-2 spike protein within the concentration range of 1 to 100 ng/mL after four hours of incubation. Further investigation of pH and temperature showed minimal influence on the PDA sensor for the detection of COVID-19 disease. After exposure to the SARS-CoV-2 spike protein, smartphone images of the PDA sensor were used to assess the sensor output by using the red chromatic shift (RCS) of the signal response. These results indicate the potential and practical use of this PDA sensor design for the rapid, colorimetric detection of COVID-19 disease in developing countries with limited access to medical testing. Full article
(This article belongs to the Section Biosensors and Healthcare)
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14 pages, 1798 KiB  
Article
Investigation of the “Antigen Hook Effect” in Lateral Flow Sandwich Immunoassay: The Case of Lumpy Skin Disease Virus Detection
by Simone Cavalera, Giulia Pezzoni, Santina Grazioli, Emiliana Brocchi, Stefano Baselli, Davide Lelli, Barbara Colitti, Thea Serra, Fabio Di Nardo, Matteo Chiarello, Valentina Testa, Sergio Rosati, Claudio Baggiani and Laura Anfossi
Biosensors 2022, 12(9), 739; https://doi.org/10.3390/bios12090739 - 8 Sep 2022
Cited by 12 | Viewed by 3414
Abstract
Lumpy skin disease (LSD) is an infectious disease affecting bovine with severe symptomatology. The implementation of effective control strategies to prevent infection outbreak requires rapid diagnostic tools. Two monoclonal antibodies (mAbs), targeting different epitopes of the LSDV structural protein p32, and gold nanoparticles [...] Read more.
Lumpy skin disease (LSD) is an infectious disease affecting bovine with severe symptomatology. The implementation of effective control strategies to prevent infection outbreak requires rapid diagnostic tools. Two monoclonal antibodies (mAbs), targeting different epitopes of the LSDV structural protein p32, and gold nanoparticles (AuNPs) were used to set up a colorimetric sandwich-type lateral flow immunoassay (LFIA). Combinations including one or two mAbs, used either as the capture or detection reagent, were explored to investigate the hook effect due to antigen saturation by the detector antibody. The mAb-AuNP preparations were optimized by a full-factorial design of experiment to achieve maximum sensitivity. Opposite optimal conditions were selected when one Mab was used for capture and detection instead of two mAbs; thus, two rational routes for developing a highly sensitive LFIA according to Mab availability were outlined. The optimal LFIA for LSDV showed a low limit of detection (103.4 TCID50/mL), high inter- and intra-assay repeatability (CV% < 5.3%), and specificity (no cross-reaction towards 12 other viruses was observed), thus proving to be a good candidate as a useful tool for the point-of-need diagnosis of LSD. Full article
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13 pages, 2732 KiB  
Article
Gold Nanoparticle-Based Enzyme-Assisted Cyclic Amplification for the Highly-Sensitive Detection of miRNA-21
by Yang Qing, Yuxing Yang, Ping Ouyang, Chenxin Fang, Haobin Fang, Yazhen Liao, Haiyu Li, Zhencui Wang and Jie Du
Biosensors 2022, 12(9), 724; https://doi.org/10.3390/bios12090724 - 4 Sep 2022
Cited by 4 | Viewed by 2022
Abstract
Because microRNAs (miRNAs) are biological indicators for the diagnosis, treatment, and monitoring of tumors, cancers, and other diseases, it is significant to develop a rapid, sensitive, and reliable miRNA detection platform. In this study, based on miRNA-21 detection, DNA-a with a 3′ end [...] Read more.
Because microRNAs (miRNAs) are biological indicators for the diagnosis, treatment, and monitoring of tumors, cancers, and other diseases, it is significant to develop a rapid, sensitive, and reliable miRNA detection platform. In this study, based on miRNA-21 detection, DNA-a with a 3′ end overhang and Texas Red fluorophore-labeled 5′ end was designed, which reacts with miRNA-21 and hybridizes with exonuclease III (Exo III), where the part connected to miRNA-21 is hydrolyzed, leaving a-DNA. At the same time, miRNA-21 is released to participate in the following reaction, to achieve cyclic amplification. a-DNA reacts with DNA-b conjugated to gold nanoparticles to achieve fluorescence quenching, with the quenching value denoted as F; additionally, after adding DNA-d and linked streptavidin immunomagnetic beads (SIBs), fluorescence recovery was achieved using DNA-c, with the recovered fluorescence recorded as F0. By comparing the difference in the fluorescence (F0F) between the two experiments, the amount of DNA-a hydrolyzed to produce a-DNA was established to determine the target miRNA-21 content. Under optimized conditions, by comparing the changes in the fluorescence signal, the developed strategy shows good sensitivity and repeatability, with a detection limit of 18 pM, good discriminative ability and selectivity, and promise for the early diagnosis of breast and intestinal cancers. Full article
(This article belongs to the Special Issue DNA Biosensors for Highly Sensitive Detection)
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30 pages, 19042 KiB  
Review
Recent Advances in Digital Biosensing Technology
by Kathrine Curtin, Bethany J. Fike, Brandi Binkley, Toktam Godary and Peng Li
Biosensors 2022, 12(9), 673; https://doi.org/10.3390/bios12090673 - 23 Aug 2022
Cited by 6 | Viewed by 3749
Abstract
Digital biosensing assays demonstrate remarkable advantages over conventional biosensing systems because of their ability to achieve single-molecule detection and absolute quantification. Unlike traditional low-abundance biomarking screening, digital-based biosensing systems reduce sample volumes significantly to the fL-nL level, which vastly reduces overall reagent consumption, [...] Read more.
Digital biosensing assays demonstrate remarkable advantages over conventional biosensing systems because of their ability to achieve single-molecule detection and absolute quantification. Unlike traditional low-abundance biomarking screening, digital-based biosensing systems reduce sample volumes significantly to the fL-nL level, which vastly reduces overall reagent consumption, improves reaction time and throughput, and enables high sensitivity and single target detection. This review presents the current technology for compartmentalizing reactions and their applications in detecting proteins and nucleic acids. We also analyze existing challenges and future opportunities associated with digital biosensing and research opportunities for developing integrated digital biosensing systems. Full article
(This article belongs to the Special Issue Feature Issue of Nano- and Micro-Technologies in Biosensors Section)
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27 pages, 7813 KiB  
Review
Liquid Crystal Biosensors: Principles, Structure and Applications
by Haonan Wang, Tianhua Xu, Yaoxin Fu, Ziyihui Wang, Mark S. Leeson, Junfeng Jiang and Tiegen Liu
Biosensors 2022, 12(8), 639; https://doi.org/10.3390/bios12080639 - 14 Aug 2022
Cited by 24 | Viewed by 4384
Abstract
Liquid crystals (LCs) have been widely used as sensitive elements to construct LC biosensors based on the principle that specific bonding events between biomolecules can affect the orientation of LC molecules. On the basis of the sensing interface of LC molecules, LC biosensors [...] Read more.
Liquid crystals (LCs) have been widely used as sensitive elements to construct LC biosensors based on the principle that specific bonding events between biomolecules can affect the orientation of LC molecules. On the basis of the sensing interface of LC molecules, LC biosensors can be classified into three types: LC–solid interface sensing platforms, LC–aqueous interface sensing platforms, and LC–droplet interface sensing platforms. In addition, as a signal amplification method, the combination of LCs and whispering gallery mode (WGM) optical microcavities can provide higher detection sensitivity due to the extremely high quality factor and the small mode volume of the WGM optical microcavity, which enhances the interaction between the light field and biotargets. In this review, we present an overview of the basic principles, the structure, and the applications of LC biosensors. We discuss the important properties of LC and the principle of LC biosensors. The different geometries of LCs in the biosensing systems as well as their applications in the biological detection are then described. The fabrication and the application of the LC-based WGM microcavity optofluidic sensor in the biological detection are also introduced. Finally, challenges and potential research opportunities in the development of LC-based biosensors are discussed. Full article
(This article belongs to the Special Issue Frontiers in Liquid Crystal-Based Biosensors)
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25 pages, 5089 KiB  
Review
Research Progress and Future Trends of Microfluidic Paper-Based Analytical Devices in In-Vitro Diagnosis
by Taiyi Zhang, Feng Ding, Yujing Yang, Gaozhen Zhao, Chuanhao Zhang, Ruiming Wang and Xiaowen Huang
Biosensors 2022, 12(7), 485; https://doi.org/10.3390/bios12070485 - 3 Jul 2022
Cited by 20 | Viewed by 4048
Abstract
In vitro diagnosis (IVD) has become a hot topic in laboratory research and achievement transformation. However, due to the high cost, and time-consuming and complex operation of traditional technologies, some new technologies are being introduced into IVD, to solve the existing problems. As [...] Read more.
In vitro diagnosis (IVD) has become a hot topic in laboratory research and achievement transformation. However, due to the high cost, and time-consuming and complex operation of traditional technologies, some new technologies are being introduced into IVD, to solve the existing problems. As a result, IVD has begun to develop toward point-of-care testing (POCT), a subdivision field of IVD. The pandemic has made governments and health institutions realize the urgency of accelerating the development of POCT. Microfluidic paper-based analytical devices (μPADs), a low-cost, high-efficiency, and easy-to-operate detection platform, have played a significant role in advancing the development of IVD. μPADs are composed of paper as the core material, certain unique substances as reagents for processing the paper, and sensing devices, as auxiliary equipment. The published reviews on the same topic lack a comprehensive and systematic introduction to μPAD classification and research progress in IVD segmentation. In this paper, we first briefly introduce the origin of μPADs and their role in promoting IVD, in the introduction section. Then, processing and detection methods for μPADs are summarized, and the innovative achievements of μPADs in IVD are reviewed. Finally, we discuss and prospect the upgrade and improvement directions of μPADs, in terms of portability, sensitivity, and automation, to help researchers clarify the progress and overcome the difficulties in subsequent μPAD research. Full article
(This article belongs to the Special Issue Electrical/Optical Biosensing and Regulating Technology)
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15 pages, 1028 KiB  
Review
Transcription Factor-Based Biosensors for Detecting Pathogens
by Yangwon Jeon, Yejin Lee, Keugtae Kim, Geupil Jang and Youngdae Yoon
Biosensors 2022, 12(7), 470; https://doi.org/10.3390/bios12070470 - 29 Jun 2022
Cited by 7 | Viewed by 3289
Abstract
Microorganisms are omnipresent and inseparable from our life. Many of them are beneficial to humans, while some are not. Importantly, foods and beverages are susceptible to microbial contamination, with their toxins causing illnesses and even death in some cases. Therefore, monitoring and detecting [...] Read more.
Microorganisms are omnipresent and inseparable from our life. Many of them are beneficial to humans, while some are not. Importantly, foods and beverages are susceptible to microbial contamination, with their toxins causing illnesses and even death in some cases. Therefore, monitoring and detecting harmful microorganisms are critical to ensuring human health and safety. For several decades, many methods have been developed to detect and monitor microorganisms and their toxicants. Conventionally, nucleic acid analysis and antibody-based analysis were used to detect pathogens. Additionally, diverse chromatographic methods were employed to detect toxins based on their chemical and structural properties. However, conventional techniques have several disadvantages concerning analysis time, sensitivity, and expense. With the advances in biotechnology, new approaches to detect pathogens and toxins have been reported to compensate for the disadvantages of conventional analysis from different research fields, including electrochemistry, nanotechnology, and molecular biology. Among them, we focused on the recent studies of transcription factor (TF)-based biosensors to detect microorganisms and discuss their perspectives and applications. Additionally, the other biosensors for detecting microorganisms reported in recent studies were also introduced in this review. Full article
(This article belongs to the Special Issue Microbial Toxins and Pathogen Biodetection)
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31 pages, 11792 KiB  
Review
Advances of MXenes; Perspectives on Biomedical Research
by Aneesh Koyappayil, Sachin Ganpat Chavan, Yun-Gil Roh and Min-Ho Lee
Biosensors 2022, 12(7), 454; https://doi.org/10.3390/bios12070454 - 25 Jun 2022
Cited by 25 | Viewed by 5677
Abstract
The last decade witnessed the emergence of a new family of 2D transition metal carbides and nitrides named MXenes, which quickly gained momentum due to their exceptional electrical, mechanical, optical, and tunable functionalities. These outstanding properties also rendered them attractive materials for biomedical [...] Read more.
The last decade witnessed the emergence of a new family of 2D transition metal carbides and nitrides named MXenes, which quickly gained momentum due to their exceptional electrical, mechanical, optical, and tunable functionalities. These outstanding properties also rendered them attractive materials for biomedical and biosensing applications, including drug delivery systems, antimicrobial applications, tissue engineering, sensor probes, auxiliary agents for photothermal therapy and hyperthermia applications, etc. The hydrophilic nature of MXenes with rich surface functional groups is advantageous for biomedical applications over hydrophobic nanoparticles that may require complicated surface modifications. As an emerging 2D material with numerous phases and endless possible combinations with other 2D materials, 1D materials, nanoparticles, macromolecules, polymers, etc., MXenes opened a vast terra incognita for diverse biomedical applications. Recently, MXene research picked up the pace and resulted in a flood of literature reports with significant advancements in the biomedical field. In this context, this review will discuss the recent advancements, design principles, and working mechanisms of some interesting MXene-based biomedical applications. It also includes major progress, as well as key challenges of various types of MXenes and functional MXenes in conjugation with drug molecules, metallic nanoparticles, polymeric substrates, and other macromolecules. Finally, the future possibilities and challenges of this magnificent material are discussed in detail. Full article
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35 pages, 3770 KiB  
Review
Living Sample Viability Measurement Methods from Traditional Assays to Nanomotion
by Hamzah Al-madani, Hui Du, Junlie Yao, Hao Peng, Chenyang Yao, Bo Jiang, Aiguo Wu and Fang Yang
Biosensors 2022, 12(7), 453; https://doi.org/10.3390/bios12070453 - 24 Jun 2022
Cited by 16 | Viewed by 3097
Abstract
Living sample viability measurement is an extremely common process in medical, pharmaceutical, and biological fields, especially drug pharmacology and toxicology detection. Nowadays, there are a number of chemical, optical, and mechanical methods that have been developed in response to the growing demand for [...] Read more.
Living sample viability measurement is an extremely common process in medical, pharmaceutical, and biological fields, especially drug pharmacology and toxicology detection. Nowadays, there are a number of chemical, optical, and mechanical methods that have been developed in response to the growing demand for simple, rapid, accurate, and reliable real-time living sample viability assessment. In parallel, the development trend of viability measurement methods (VMMs) has increasingly shifted from traditional assays towards the innovative atomic force microscope (AFM) oscillating sensor method (referred to as nanomotion), which takes advantage of the adhesion of living samples to an oscillating surface. Herein, we provide a comprehensive review of the common VMMs, laying emphasis on their benefits and drawbacks, as well as evaluating the potential utility of VMMs. In addition, we discuss the nanomotion technique, focusing on its applications, sample attachment protocols, and result display methods. Furthermore, the challenges and future perspectives on nanomotion are commented on, mainly emphasizing scientific restrictions and development orientations. Full article
(This article belongs to the Special Issue Nanoprobes for Tumor Theranostics)
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9 pages, 1776 KiB  
Communication
Nucleic Acids Detection for Mycobacterium tuberculosis Based on Gold Nanoparticles Counting and Rolling-Circle Amplification
by Xiaojing Pei, Hu Hong, Sitong Liu and Na Li
Biosensors 2022, 12(7), 448; https://doi.org/10.3390/bios12070448 - 23 Jun 2022
Cited by 5 | Viewed by 2247
Abstract
Tuberculosis (TB) is a common infectious disease caused by Mycobacterium tuberculosis, which usually disturbs the lungs, and remains the second leading cause of death from an infectious disease worldwide after the human immunodeficiency virus. Herein, we constructed a simple and sensitive method [...] Read more.
Tuberculosis (TB) is a common infectious disease caused by Mycobacterium tuberculosis, which usually disturbs the lungs, and remains the second leading cause of death from an infectious disease worldwide after the human immunodeficiency virus. Herein, we constructed a simple and sensitive method for Mycobacterium tuberculosis-specific DNA detection with the dark-field microscopic imaging of gold nanoparticles (AuNPs) counting strategy and rolling-circle amplification (RCA). Taking advantage of RCA amplification, one target molecule produced hundreds of general oligonucleotides, which could form the sandwich structure with capture-strand-modified magnetic beads and AuNPs. After magnetic separation, AuNPs were released and detected by dark-field imaging; about 10 fM Mycobacterium tuberculosis-specific DNA target can still be differentiated from the blank. No significant change of the absorbance signals was observed when the target DNA to genomic DNA ratio (in mass) was from 1:0 to 1:106. The spike recovery results in genomic DNA from human and Klebsiella pneumoniae suggested that the proposed method has the feasibility for application with biological samples. This proposed method is performed on an entry-level dark-field microscope setup with only a 6 μL detection volume, which creates a new, simple, sensitive, and valuable tool for pathogen detection. Full article
(This article belongs to the Special Issue Fast and Sensitive Detection of Nucleic Acid)
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31 pages, 5022 KiB  
Review
Advances in Detection of Antibiotic Pollutants in Aqueous Media Using Molecular Imprinting Technique—A Review
by Akinrinade George Ayankojo, Jekaterina Reut, Vu Bao Chau Nguyen, Roman Boroznjak and Vitali Syritski
Biosensors 2022, 12(7), 441; https://doi.org/10.3390/bios12070441 - 23 Jun 2022
Cited by 22 | Viewed by 3725
Abstract
Antibiotics constitute one of the emerging categories of persistent organic pollutants, characterised by their expansion of resistant pathogens. Antibiotic pollutants create a major public health challenge, with already identifiable detrimental effects on human and animal health. A fundamental aspect of controlling and preventing [...] Read more.
Antibiotics constitute one of the emerging categories of persistent organic pollutants, characterised by their expansion of resistant pathogens. Antibiotic pollutants create a major public health challenge, with already identifiable detrimental effects on human and animal health. A fundamental aspect of controlling and preventing the spread of pollutants is the continuous screening and monitoring of environmental samples. Molecular imprinting is a state-of-the-art technique for designing robust biomimetic receptors called molecularly imprinted polymers (MIPs), which mimic natural biomolecules in target-selective recognition. When integrated with an appropriate sensor transducer, MIP demonstrates a potential for the needed environmental monitoring, thus justifying the observed rise in interest in this field of research. This review examines scientific interventions within the last decade on the determination of antibiotic water pollutants using MIP receptors interfaced with label-free sensing platforms, with an expanded focus on optical, piezoelectric, and electrochemical systems. Following these, the review evaluates the analytical performance of outstanding MIP-based sensors for environmentally significant antibiotics, while highlighting the importance of computational chemistry in functional monomer selection and the strategies for signal amplification and performance improvement. Lastly, the review points out the future trends in antibiotic MIP research, as it transits from a proof of concept to the much demanded commercially available entity. Full article
(This article belongs to the Special Issue Current Trends in Polymer-Based Biosensors)
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23 pages, 6274 KiB  
Review
Bioluminescence Color-Tuning Firefly Luciferases: Engineering and Prospects for Real-Time Intracellular pH Imaging and Heavy Metal Biosensing
by Vadim R. Viviani, Gabriel F. Pelentir and Vanessa R. Bevilaqua
Biosensors 2022, 12(6), 400; https://doi.org/10.3390/bios12060400 - 10 Jun 2022
Cited by 12 | Viewed by 3499
Abstract
Firefly luciferases catalyze the efficient production of yellow-green light under normal physiological conditions, having been extensively used for bioanalytical purposes for over 5 decades. Under acidic conditions, high temperatures and the presence of heavy metals, they produce red light, a property that is [...] Read more.
Firefly luciferases catalyze the efficient production of yellow-green light under normal physiological conditions, having been extensively used for bioanalytical purposes for over 5 decades. Under acidic conditions, high temperatures and the presence of heavy metals, they produce red light, a property that is called pH-sensitivity or pH-dependency. Despite the demand for physiological intracellular biosensors for pH and heavy metals, firefly luciferase pH and metal sensitivities were considered drawbacks in analytical assays. We first demonstrated that firefly luciferases and their pH and metal sensitivities can be harnessed to estimate intracellular pH variations and toxic metal concentrations through ratiometric analysis. Using Macrolampis sp2 firefly luciferase, the intracellular pH could be ratiometrically estimated in bacteria and then in mammalian cells. The luciferases of Macrolampis sp2 and Cratomorphus distinctus fireflies were also harnessed to ratiometrically estimate zinc, mercury and other toxic metal concentrations in the micromolar range. The temperature was also ratiometrically estimated using firefly luciferases. The identification and engineering of metal-binding sites have allowed the development of novel luciferases that are more specific to certain metals. The luciferase of the Amydetes viviani firefly was selected for its special sensitivity to cadmium and mercury, and for its stability at higher temperatures. These color-tuning luciferases can potentially be used with smartphones for hands-on field analysis of water contamination and biochemistry teaching assays. Thus, firefly luciferases are novel color-tuning sensors for intracellular pH and toxic metals. Furthermore, a single luciferase gene is potentially useful as a dual bioluminescent reporter to simultaneously report intracellular ATP and/or luciferase concentrations luminometrically, and pH or metal concentrations ratiometrically, providing a useful tool for real-time imaging of intracellular dynamics and stress. Full article
(This article belongs to the Special Issue Biosensing and Drug Delivery)
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14 pages, 1701 KiB  
Review
Towards Development of Molecularly Imprinted Electrochemical Sensors for Food and Drug Safety: Progress and Trends
by Shuhong Zhou, Chen Liu, Jianguo Lin, Zhi Zhu, Bing Hu and Long Wu
Biosensors 2022, 12(6), 369; https://doi.org/10.3390/bios12060369 - 27 May 2022
Cited by 15 | Viewed by 2850
Abstract
Due to their advantages of good flexibility, low cost, simple operations, and small equipment size, electrochemical sensors have been commonly employed in food safety. However, when they are applied to detect various food or drug samples, their stability and specificity can be greatly [...] Read more.
Due to their advantages of good flexibility, low cost, simple operations, and small equipment size, electrochemical sensors have been commonly employed in food safety. However, when they are applied to detect various food or drug samples, their stability and specificity can be greatly influenced by the complex matrix. By combining electrochemical sensors with molecular imprinting techniques (MIT), they will be endowed with new functions of specific recognition and separation, which make them powerful tools in analytical fields. MIT-based electrochemical sensors (MIECs) require preparing or modifying molecularly imprinted polymers (MIPs) on the electrode surface. In this review, we explored different MIECs regarding the design, working principle and functions. Additionally, the applications of MIECs in food and drug safety were discussed, as well as the challenges and prospects for developing new electrochemical methods. The strengths and weaknesses of MIECs including low stability and electrode fouling are discussed to indicate the research direction for future electrochemical sensors. Full article
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23 pages, 6629 KiB  
Article
Portable Respiration Monitoring System with an Embroidered Capacitive Facemask Sensor
by Mitar Simić, Adrian K. Stavrakis, Ankita Sinha, Velibor Premčevski, Branko Markoski and Goran M. Stojanović
Biosensors 2022, 12(5), 339; https://doi.org/10.3390/bios12050339 - 15 May 2022
Cited by 18 | Viewed by 3843
Abstract
Respiration monitoring is a very important indicator of health status. It can be used as a marker in the recognition of a variety of diseases, such as sleep apnea, asthma or cardiac arrest. The purpose of the present study is to overcome limitations [...] Read more.
Respiration monitoring is a very important indicator of health status. It can be used as a marker in the recognition of a variety of diseases, such as sleep apnea, asthma or cardiac arrest. The purpose of the present study is to overcome limitations of the current state of the art in the field of respiration monitoring systems. Our goal was the development of a lightweight handheld device with portable operation and low power consumption. The proposed approach includes a textile capacitive sensor with interdigitated electrodes embroidered into the facemask, integrated with readout electronics. Readout electronics is based on the direct interface of the capacitive sensor and a microcontroller through just one analog and one digital pin. The microcontroller board and sensor are powered by a smartphone or PC through a USB cable. The developed mobile application for the Android™ operating system offers reliable data acquisition and acts as a bridge for data transfer to the remote server. The embroidered sensor was initially tested in a humidity-controlled chamber connected to a commercial impedance analyzer. Finally, in situ testing with 10 volunteering subjects confirmed stable operation with reliable respiration monitoring. Full article
(This article belongs to the Special Issue Electrochemical (Bio)Sensors and Energy Autonomous Sensing System)
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14 pages, 2825 KiB  
Article
Field-Effect Capacitors Decorated with Ligand-Stabilized Gold Nanoparticles: Modeling and Experiments
by Arshak Poghossian, Tobias Karschuck, Patrick Wagner and Michael J. Schöning
Biosensors 2022, 12(5), 334; https://doi.org/10.3390/bios12050334 - 13 May 2022
Cited by 3 | Viewed by 2285
Abstract
Nanoparticles are recognized as highly attractive tunable materials for designing field-effect biosensors with enhanced performance. In this work, we present a theoretical model for electrolyte-insulator-semiconductor capacitors (EISCAP) decorated with ligand-stabilized charged gold nanoparticles. The charged AuNPs are taken into account as additional, nanometer-sized [...] Read more.
Nanoparticles are recognized as highly attractive tunable materials for designing field-effect biosensors with enhanced performance. In this work, we present a theoretical model for electrolyte-insulator-semiconductor capacitors (EISCAP) decorated with ligand-stabilized charged gold nanoparticles. The charged AuNPs are taken into account as additional, nanometer-sized local gates. The capacitance-voltage (CV) curves and constant-capacitance (ConCap) signals of the AuNP-decorated EISCAPs have been simulated. The impact of the AuNP coverage on the shift of the CV curves and the ConCap signals was also studied experimentally on Al–p-Si–SiO2 EISCAPs decorated with positively charged aminooctanethiol-capped AuNPs. In addition, the surface of the EISCAPs, modified with AuNPs, was characterized by scanning electron microscopy for different immobilization times of the nanoparticles. Full article
(This article belongs to the Special Issue Biosensors in Nanotechnology)
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14 pages, 3684 KiB  
Article
A Digital Microfluidic Device Integrated with Electrochemical Impedance Spectroscopy for Cell-Based Immunoassay
by Yuqian Zhang and Yuguang Liu
Biosensors 2022, 12(5), 330; https://doi.org/10.3390/bios12050330 - 12 May 2022
Cited by 18 | Viewed by 3800
Abstract
The dynamic immune response to various diseases and therapies has been considered a promising indicator of disease status and therapeutic effectiveness. For instance, the human peripheral blood mononuclear cell (PBMC), as a major player in the immune system, is an important index to [...] Read more.
The dynamic immune response to various diseases and therapies has been considered a promising indicator of disease status and therapeutic effectiveness. For instance, the human peripheral blood mononuclear cell (PBMC), as a major player in the immune system, is an important index to indicate a patient’s immune function. Therefore, establishing a simple yet sensitive tool that can frequently assess the immune system during the course of disease and treatment is of great importance. This study introduced an integrated system that includes an electrochemical impedance spectroscope (EIS)-based biosensor in a digital microfluidic (DMF) device, to quantify the PBMC abundance with minimally trained hands. Moreover, we exploited the unique droplet manipulation feature of the DMF platform and conducted a dynamic cell capture assay, which enhanced the detection signal by 2.4-fold. This integrated system was able to detect as few as 104 PBMCs per mL, presenting suitable sensitivity to quantify PBMCs. This integrated system is easy-to-operate and sensitive, and therefore holds great potential as a powerful tool to profile immune-mediated therapeutic responses in a timely manner, which can be further evolved as a point-of-care diagnostic device to conduct near-patient tests from blood samples. Full article
(This article belongs to the Special Issue Immunosensors - Trends and Perspective)
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49 pages, 4493 KiB  
Review
Recent Progress in Non-Enzymatic Electroanalytical Detection of Pesticides Based on the Use of Functional Nanomaterials as Electrode Modifiers
by Tanja Vrabelj and Matjaž Finšgar
Biosensors 2022, 12(5), 263; https://doi.org/10.3390/bios12050263 - 20 Apr 2022
Cited by 12 | Viewed by 3236
Abstract
This review presents recent advances in the non-enzymatic electrochemical detection and quantification of pesticides, focusing on the use of nanomaterial-based electrode modifiers and their corresponding analytical response. The use of bare glassy carbon electrodes, carbon paste electrodes, screen-printed electrodes, and other electrodes in [...] Read more.
This review presents recent advances in the non-enzymatic electrochemical detection and quantification of pesticides, focusing on the use of nanomaterial-based electrode modifiers and their corresponding analytical response. The use of bare glassy carbon electrodes, carbon paste electrodes, screen-printed electrodes, and other electrodes in this research area is presented. The sensors were modified with single nanomaterials, a binary composite, or triple and multiple nanocomposites applied to the electrodes’ surfaces using various application techniques. Regardless of the type of electrode used and the class of pesticides analysed, carbon-based nanomaterials, metal, and metal oxide nanoparticles are investigated mainly for electrochemical analysis because they have a high surface-to-volume ratio and, thus, a large effective area, high conductivity, and (electro)-chemical stability. This work demonstrates the progress made in recent years in the non-enzymatic electrochemical analysis of pesticides. The need for simultaneous detection of multiple pesticides with high sensitivity, low limit of detection, high precision, and high accuracy remains a challenge in analytical chemistry. Full article
(This article belongs to the Section Biosensor Materials)
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11 pages, 3816 KiB  
Article
An Artificial Intelligence-Enhanced Blood Pressure Monitor Wristband Based on Piezoelectric Nanogenerator
by Puchuan Tan, Yuan Xi, Shengyu Chao, Dongjie Jiang, Zhuo Liu, Yubo Fan and Zhou Li
Biosensors 2022, 12(4), 234; https://doi.org/10.3390/bios12040234 - 11 Apr 2022
Cited by 31 | Viewed by 6024
Abstract
Hypertensive patients account for about 16% to 37% of the global population, and about 9.4 million people die each year from hypertension and its complications. Blood pressure is an important indicator for diagnosing hypertension. Currently, blood pressure measurement methods are mainly based on [...] Read more.
Hypertensive patients account for about 16% to 37% of the global population, and about 9.4 million people die each year from hypertension and its complications. Blood pressure is an important indicator for diagnosing hypertension. Currently, blood pressure measurement methods are mainly based on mercury sphygmomanometers in hospitals or electronic sphygmomanometers at home. However, people’s blood pressure changes with time, and using only the blood pressure value at the current moment to judge hypertension may cause misdiagnosis. Continuous blood pressure measurement can monitor sudden increases in blood pressure, and can also provide physicians with long-term continuous blood pressure changes as a diagnostic reference. In this article, we design an artificial intelligence-enhanced blood pressure monitoring wristband. The wristband’s sensors are based on piezoelectric nanogenerators, with a high signal-to-noise ratio of 29.7 dB. Through the transformer deep learning model, the wristband can predict blood pressure readings, and the loss value is lower than 4 mmHg. By wearing this blood pressure monitoring wristband, we realized three days of continuous blood pressure monitoring of the subjects. The blood pressure monitoring wristband is lightweight, has profound significance for the prevention and treatment of hypertension, and has wide application prospects in medical, military, aerospace and other fields. Full article
(This article belongs to the Special Issue Self-Powered Flexible Biosensors and Electronic Skin)
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40 pages, 1372 KiB  
Review
The Current State of Optical Sensors in Medical Wearables
by Erik Vavrinsky, Niloofar Ebrahimzadeh Esfahani, Michal Hausner, Anton Kuzma, Vratislav Rezo, Martin Donoval and Helena Kosnacova
Biosensors 2022, 12(4), 217; https://doi.org/10.3390/bios12040217 - 6 Apr 2022
Cited by 40 | Viewed by 10409
Abstract
Optical sensors play an increasingly important role in the development of medical diagnostic devices. They can be very widely used to measure the physiology of the human body. Optical methods include PPG, radiation, biochemical, and optical fiber sensors. Optical sensors offer excellent metrological [...] Read more.
Optical sensors play an increasingly important role in the development of medical diagnostic devices. They can be very widely used to measure the physiology of the human body. Optical methods include PPG, radiation, biochemical, and optical fiber sensors. Optical sensors offer excellent metrological properties, immunity to electromagnetic interference, electrical safety, simple miniaturization, the ability to capture volumes of nanometers, and non-invasive examination. In addition, they are cheap and resistant to water and corrosion. The use of optical sensors can bring better methods of continuous diagnostics in the comfort of the home and the development of telemedicine in the 21st century. This article offers a large overview of optical wearable methods and their modern use with an insight into the future years of technology in this field. Full article
(This article belongs to the Special Issue Advanced Optical Sensing Techniques for Applications in Biomedicine)
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31 pages, 3095 KiB  
Review
Overview of Liquid Crystal Biosensors: From Basic Theory to Advanced Applications
by Ruixiang Qu and Guoqiang Li
Biosensors 2022, 12(4), 205; https://doi.org/10.3390/bios12040205 - 29 Mar 2022
Cited by 16 | Viewed by 4585
Abstract
Liquid crystals (LCs), as the remarkable optical materials possessing stimuli-responsive property and optical modulation property simultaneously, have been utilized to fabricate a wide variety of optical devices. Integrating the LCs and receptors together, LC biosensors aimed at detecting various biomolecules have been extensively [...] Read more.
Liquid crystals (LCs), as the remarkable optical materials possessing stimuli-responsive property and optical modulation property simultaneously, have been utilized to fabricate a wide variety of optical devices. Integrating the LCs and receptors together, LC biosensors aimed at detecting various biomolecules have been extensively explored. Compared with the traditional biosensing technologies, the LC biosensors are simple, visualized, and efficient. Owning to the irreplaceable superiorities, the research enthusiasm for the LC biosensors is rapidly rising. As a result, it is necessary to overview the development of the LC biosensors to guide future work. This article reviews the basic theory and advanced applications of LC biosensors. We first discuss different mesophases and geometries employed to fabricate LC biosensors, after which we introduce various detecting mechanisms involved in biomolecular detection. We then focus on diverse detection targets such as proteins, enzymes, nucleic acids, glucose, cholesterol, bile acids, and lipopolysaccharides. For each of these targets, the development history and state-of-the-art work are exhibited in detail. Finally, the current challenges and potential development directions of the LC biosensors are introduced briefly. Full article
(This article belongs to the Special Issue Frontiers in Liquid Crystal-Based Biosensors)
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9 pages, 1959 KiB  
Article
Transdermal Polymeric Microneedle Sensing Platform for Fentanyl Detection in Biofluid
by Pratik Joshi, Parand R. Riley, Rupesh Mishra, Sina Azizi Machekposhti and Roger Narayan
Biosensors 2022, 12(4), 198; https://doi.org/10.3390/bios12040198 - 27 Mar 2022
Cited by 21 | Viewed by 3770
Abstract
Opioid drugs are extremely potent synthetic analytes, and their abuse is common around the world. Hence, a rapid and point-of-need device is necessary to assess the presence of this compound in body fluid so that a timely countermeasure can be provided to the [...] Read more.
Opioid drugs are extremely potent synthetic analytes, and their abuse is common around the world. Hence, a rapid and point-of-need device is necessary to assess the presence of this compound in body fluid so that a timely countermeasure can be provided to the exposed individuals. Herein, we present an attractive microneedle sensing platform for the detection of the opioid drug fentanyl in real serum samples using an electrochemical detection method. The device contained an array of pyramidal microneedle structures that were integrated with platinum (Pt) and silver (Ag) wires, each with a microcavity opening. The working sensor was modified by graphene ink and subsequently with 4 (3-Butyl-1-imidazolio)-1-butanesulfonate) ionic liquid. The microneedle sensor showed direct oxidation of fentanyl in liquid samples with a detection limit of 27.8 μM by employing a highly sensitive square-wave voltammetry technique. The resulting microneedle-based sensing platform displayed an interference-free fentanyl detection in diluted serum without conceding its sensitivity, stability, and response time. The obtained results revealed that the microneedle sensor holds considerable promise for point-of-need fentanyl detection and opens additional opportunities for detecting substances of abuse in emergencies. Full article
(This article belongs to the Special Issue Feature Issue of Biosensor Materials Section)
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15 pages, 31741 KiB  
Perspective
Preparation and Applications of Electrospun Nanofibers for Wearable Biosensors
by Tengzhou Xu, Guojing Ji, Hui Li, Jiaduo Li, Zhou Chen, Desire Emefa Awuye and Jie Huang
Biosensors 2022, 12(3), 177; https://doi.org/10.3390/bios12030177 - 17 Mar 2022
Cited by 13 | Viewed by 4116
Abstract
The emergence of nanotechnology has provided many new ideas and innovations in the field of biosensors. Electrospun nanofibers have many excellent properties such as high specific surface area, high porosity, low cost, high efficiency, and they can be combined with a variety of [...] Read more.
The emergence of nanotechnology has provided many new ideas and innovations in the field of biosensors. Electrospun nanofibers have many excellent properties such as high specific surface area, high porosity, low cost, high efficiency, and they can be combined with a variety of sensors. These remarkable features have a wide range of applications in the field of sensors such as monitoring air pollutants, highly sensitive pressure sensors, and biosensors for monitoring the pulse of the body. This paper summarizes the working principle and influencing factors of electrospinning nanofibers, and illustrates their applications in wearable biosensors. Full article
(This article belongs to the Special Issue Lab on a Chip Technology for Pathogen Detection and Disease Diagnosis)
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21 pages, 2442 KiB  
Article
Towards a Point-of-Care (POC) Diagnostic Platform for the Multiplex Electrochemiluminescent (ECL) Sensing of Mild Traumatic Brain Injury (mTBI) Biomarkers
by Milica Jović, Denis Prim, Edis Saini and Marc Emil Pfeifer
Biosensors 2022, 12(3), 172; https://doi.org/10.3390/bios12030172 - 11 Mar 2022
Cited by 7 | Viewed by 5169
Abstract
Globally, 70 million people are annually affected by TBI. A significant proportion of all TBI cases are actually mild TBI (concussion, 70–85%), which is considerably more difficult to diagnose due to the absence of apparent symptoms. Current clinical practice of diagnosing mTBI largely [...] Read more.
Globally, 70 million people are annually affected by TBI. A significant proportion of all TBI cases are actually mild TBI (concussion, 70–85%), which is considerably more difficult to diagnose due to the absence of apparent symptoms. Current clinical practice of diagnosing mTBI largely resides on the patients’ history, clinical aspects, and CT and MRI neuroimaging observations. The latter methods are costly, time-consuming, and not amenable for decentralized or accident site measurements. As an alternative (and/or complementary), mTBI diagnostics can be performed by detection of mTBI biomarkers from patients’ blood. Herein, we proposed two strategies for the detection of three mTBI-relevant biomarkers (GFAP, h-FABP, and S100β), in standard solutions and in human serum samples by using an electrochemiluminescence (ECL) immunoassay on (i) a commercial ECL platform in 96-well plate format, and (ii) a “POC-friendly” platform with disposable screen-printed carbon electrodes (SPCE) and a portable ECL reader. We further demonstrated a proof-of-concept for integrating three individually developed mTBI assays (“singleplex”) into a three-plex (“multiplex”) assay on a single SPCE using a spatially resolved ECL approach. The presented methodology demonstrates feasibility and a first step towards the development of a rapid POC multiplex diagnostic system for the detection of a mTBI biomarker panel on a single SPCE. Full article
(This article belongs to the Section Biosensors and Healthcare)
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11 pages, 3242 KiB  
Article
Compact Surface Plasmon Resonance IgG Sensor Based on H-Shaped Optical Fiber
by Yijian Huang, Ying Wang, Gaixia Xu, Xing Rao, Jiaxiong Zhang, Xun Wu, Changrui Liao and Yiping Wang
Biosensors 2022, 12(3), 141; https://doi.org/10.3390/bios12030141 - 25 Feb 2022
Cited by 16 | Viewed by 2961
Abstract
A compact surface plasmon resonance sensor based on an H-shaped optical fiber is proposed and demonstrated. The H-shaped optical fiber was fabricated experimentally by using hydrofluoric acid to controllably corrode the polarization-maintaining fiber. A satisfactory distance between the outer surface of the fiber [...] Read more.
A compact surface plasmon resonance sensor based on an H-shaped optical fiber is proposed and demonstrated. The H-shaped optical fiber was fabricated experimentally by using hydrofluoric acid to controllably corrode the polarization-maintaining fiber. A satisfactory distance between the outer surface of the fiber and the core can be achieved, and then the surface plasmon resonance effect can be excited by coating a metal film of appropriate thickness on the surface of the fiber. This technology can realize the preparation of multiple samples at one time, compared to the traditional side-polishing technique. The H-shaped optical fiber obtained from corrosion exhibits a high surface quality and short lengths, down to only a few hundred microns. The effects of the proposed H-shaped optical fiber on spectral properties are induced by process parameters, including fiber remaining thickness, coating thickness and fiber length, and were investigated in detail. The prepared sensor was used for the specific detection of human IgG, and the minimum human IgG concentration that the sensor can distinguish is 3.4 μg/mL. Such a compact surface plasmon resonance fiber sensor has the advantages of an easy fabrication, good consistency and low cost, and is expected to be applied in the specific detection of biomarkers. Full article
(This article belongs to the Special Issue Recent Progress of Optical Fiber Based Biosensors)
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11 pages, 1789 KiB  
Perspective
Graphene Quantum Dots-Based Electrochemical Biosensing Platform for Early Detection of Acute Myocardial Infarction
by Tanveer A. Tabish, Hasan Hayat, Aumber Abbas and Roger J. Narayan
Biosensors 2022, 12(2), 77; https://doi.org/10.3390/bios12020077 - 28 Jan 2022
Cited by 32 | Viewed by 6279
Abstract
Heart failure resulting from acute myocardial infarction (AMI) is an important global health problem. Treatments of heart failure and AMI have improved significantly over the past two decades; however, the available diagnostic tests only give limited insights into these heterogeneous conditions at a [...] Read more.
Heart failure resulting from acute myocardial infarction (AMI) is an important global health problem. Treatments of heart failure and AMI have improved significantly over the past two decades; however, the available diagnostic tests only give limited insights into these heterogeneous conditions at a reversible stage and are not precise enough to evaluate the status of the tissue at high risk. Innovative diagnostic tools for more accurate, more reliable, and early diagnosis of AMI are urgently needed. A promising solution is the timely identification of prognostic biomarkers, which is crucial for patients with AMI, as myocardial dysfunction and infarction lead to more severe and irreversible changes in the cardiovascular system over time. The currently available biomarkers for AMI detection include cardiac troponin I (cTnI), cardiac troponin T (cTnT), myoglobin, lactate dehydrogenase, C-reactive protein, and creatine kinase and myoglobin. Most recently, electrochemical biosensing technologies coupled with graphene quantum dots (GQDs) have emerged as a promising platform for the identification of troponin and myoglobin. The results suggest that GQDs-integrated electrochemical biosensors can provide useful prognostic information about AMI at an early, reversible, and potentially curable stage. GQDs offer several advantages over other nanomaterials that are used for the electrochemical detection of AMI such as strong interactions between cTnI and GQDs, low biomarker consumption, and reusability of the electrode; graphene-modified electrodes demonstrate excellent electrochemical responses due to the conductive nature of graphene and other features of GQDs (e.g., high specific surface area, π–π interactions with the analyte, facile electron-transfer mechanisms, size-dependent optical features, interplay between bandgap and photoluminescence, electrochemical luminescence emission capability, biocompatibility, and ease of functionalization). Other advantages include the presence of functional groups such as hydroxyl, carboxyl, carbonyl, and epoxide groups, which enhance the solubility and dispersibility of GQDs in a wide variety of solvents and biological media. In this perspective article, we consider the emerging knowledge regarding the early detection of AMI using GQDs-based electrochemical sensors and address the potential role of this sensing technology which might lead to more efficient care of patients with AMI. Full article
(This article belongs to the Special Issue Advances in Quantum Dots Biosensing)
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15 pages, 7083 KiB  
Article
Love Wave Sensor with High Penetration Depth for Potential Application in Cell Monitoring
by Pedro A. Segura Chávez, Jérémy Bonhomme, Mohamed Lamine Fayçal Bellaredj, Lucile Olive, Denis Beyssen, Mourad Oudich, Paul G. Charette and Frédéric Sarry
Biosensors 2022, 12(2), 61; https://doi.org/10.3390/bios12020061 - 24 Jan 2022
Cited by 4 | Viewed by 3673
Abstract
Love wave (L-SAW) sensors have been used to probe cell monolayers, but their application to detect changes beyond the focal adhesion points on cell monolayers, as viscosity changes on the cytoskeleton, has not been explored. In this work we present for the first [...] Read more.
Love wave (L-SAW) sensors have been used to probe cell monolayers, but their application to detect changes beyond the focal adhesion points on cell monolayers, as viscosity changes on the cytoskeleton, has not been explored. In this work we present for the first time a Love wave sensor with tuned penetration depth and sensitivity to potentially detect mechanical changes beyond focal adhesion points of cell monolayers. We designed and fabricated a Love wave sensor operating at 30 MHz with sensitivity to detect viscous changes between 0.89 and 3.3 cP. The Love wave sensor was modeled using an acoustic transmission line model, whereas the response of interdigital transducers (IDTs) was modeled with the Campbell’s cross-field circuit model. Our design uses a substrate with a high electromechanical coupling coefficient (LiNbO3 36Y-X), and an 8-µm polymeric guiding layer (SU-8). The design aims to overcome the high insertion losses of viscous liquid environments, and the loss of sensitivity due to the low frequency. The fabricated sensor was tested in a fluidic chamber glued directly to the SU-8 guiding layer. Our experiments with liquids of viscosity similar to those expected in cell monolayers showed a measurable sensor response. In addition, experimentation with SaOs-2 cells within a culture medium showed measurable responses. These results can be of interest for the development of novel cell-based biosensors, and novel characterization tools for cell monolayers. Full article
(This article belongs to the Section Biosensor Materials)
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20 pages, 4040 KiB  
Article
Development and In-Depth Characterization of Bacteria Repellent and Bacteria Adhesive Antibody-Coated Surfaces Using Optical Waveguide Biosensing
by Eniko Farkas, Robert Tarr, Tamás Gerecsei, Andras Saftics, Kinga Dóra Kovács, Balazs Stercz, Judit Domokos, Beatrix Peter, Sandor Kurunczi, Inna Szekacs, Attila Bonyár, Anita Bányai, Péter Fürjes, Szilvia Ruszkai-Szaniszló, Máté Varga, Barnabás Szabó, Eszter Ostorházi, Dóra Szabó and Robert Horvath
Biosensors 2022, 12(2), 56; https://doi.org/10.3390/bios12020056 - 20 Jan 2022
Cited by 8 | Viewed by 4499
Abstract
Bacteria repellent surfaces and antibody-based coatings for bacterial assays have shown a growing demand in the field of biosensors, and have crucial importance in the design of biomedical devices. However, in-depth investigations and comparisons of possible solutions are still missing. The optical waveguide [...] Read more.
Bacteria repellent surfaces and antibody-based coatings for bacterial assays have shown a growing demand in the field of biosensors, and have crucial importance in the design of biomedical devices. However, in-depth investigations and comparisons of possible solutions are still missing. The optical waveguide lightmode spectroscopy (OWLS) technique offers label-free, non-invasive, in situ characterization of protein and bacterial adsorption. Moreover, it has excellent flexibility for testing various surface coatings. Here, we describe an OWLS-based method supporting the development of bacteria repellent surfaces and characterize the layer structures and affinities of different antibody-based coatings for bacterial assays. In order to test nonspecific binding blocking agents against bacteria, OWLS chips were coated with bovine serum albumin (BSA), I-block, PAcrAM-g-(PMOXA, NH2, Si), (PAcrAM-P) and PLL-g-PEG (PP) (with different coating temperatures), and subsequent Escherichia coli adhesion was monitored. We found that the best performing blocking agents could inhibit bacterial adhesion from samples with bacteria concentrations of up to 107 cells/mL. Various immobilization methods were applied to graft a wide range of selected antibodies onto the biosensor’s surface. Simple physisorption, Mix&Go (AnteoBind) (MG) films, covalently immobilized protein A and avidin–biotin based surface chemistries were all fabricated and tested. The surface adsorbed mass densities of deposited antibodies were determined, and the biosensor;s kinetic data were evaluated to divine the possible orientations of the bacteria-capturing antibodies and determine the rate constants and footprints of the binding events. The development of affinity layers was supported by enzyme-linked immunosorbent assay (ELISA) measurements in order to test the bacteria binding capabilities of the antibodies. The best performance in the biosensor measurements was achieved by employing a polyclonal antibody in combination with protein A-based immobilization and PAcrAM-P blocking of nonspecific binding. Using this setting, a surface sensitivity of 70 cells/mm2 was demonstrated. Full article
(This article belongs to the Special Issue Feature Issue of Optical and Photonic Biosensors Section)
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15 pages, 1189 KiB  
Review
How to Find the Right RNA-Sensing CRISPR-Cas System for an In Vitro Application
by Escarlet Díaz-Galicia, Raik Grünberg and Stefan T. Arold
Biosensors 2022, 12(2), 53; https://doi.org/10.3390/bios12020053 - 19 Jan 2022
Cited by 8 | Viewed by 4447
Abstract
CRISPR-Cas systems have a great and still largely untapped potential for in vitro applications, in particular, for RNA biosensing. However, there is currently no systematic guide on selecting the most appropriate RNA-targeting CRISPR-Cas system for a given application among thousands of potential candidates. [...] Read more.
CRISPR-Cas systems have a great and still largely untapped potential for in vitro applications, in particular, for RNA biosensing. However, there is currently no systematic guide on selecting the most appropriate RNA-targeting CRISPR-Cas system for a given application among thousands of potential candidates. We provide an overview of the currently described Cas effector systems and review existing Cas-based RNA detection methods. We then propose a set of systematic selection criteria for selecting CRISPR-Cas candidates for new applications. Using this approach, we identify four candidates for in vitro RNA. Full article
(This article belongs to the Special Issue Application of CRISPR Cas Systems for Biosensing)
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12 pages, 2559 KiB  
Article
Disposable Stainless-Steel Wire-Based Electrochemical Microsensor for In Vivo Continuous Monitoring of Hydrogen Peroxide in Vein of Tomato Leaf
by Doudou Huo, Daodong Li, Songzhi Xu, Yujie Tang, Xueqian Xie, Dayong Li, Fengming Song, Yali Zhang, Aixue Li and Lijun Sun
Biosensors 2022, 12(1), 35; https://doi.org/10.3390/bios12010035 - 12 Jan 2022
Cited by 11 | Viewed by 2308
Abstract
As one of the pivotal signal molecules, hydrogen peroxide (H2O2) has been demonstrated to play important roles in many physiological processes of plants. Continuous monitoring of H2O2 in vivo could help understand its regulation mechanism more [...] Read more.
As one of the pivotal signal molecules, hydrogen peroxide (H2O2) has been demonstrated to play important roles in many physiological processes of plants. Continuous monitoring of H2O2 in vivo could help understand its regulation mechanism more clearly. In this study, a disposable electrochemical microsensor for H2O2 was developed. This microsensor consists of three parts: low-cost stainless-steel wire with a diameter of 0.1 mm modified by gold nanoparticles (disposable working electrode), an untreated platinum wire with a diameter of 0.1 mm (counter electrode), and an Ag/AgCl wire with a diameter of 0.1 mm (reference electrode), respectively. The microsensor could detect H2O2 in levels from 10 to 1000 µM and exhibited excellent selectivity. On this basis, the dynamic change in H2O2 in the vein of tomato leaf under high salinity was continuously monitored in vivo. The results showed that the production of H2O2 could be induced by high salinity within two hours. This study suggests that the disposable electrochemical microsensor not only suits continuously detecting H2O2 in microscopic plant tissue in vivo but also reduces the damage to plants. Overall, our strategy will help to pave the foundation for further investigation of the generation, transportation, and elimination mechanism of H2O2 in plants. Full article
(This article belongs to the Section Biosensor and Bioelectronic Devices)
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