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Biosensors, Volume 14, Issue 1 (January 2024) – 57 articles

Cover Story (view full-size image): Developing new approaches for elucidating bacterial membrane interactions with antimicrobial molecules is critical for combatting antibiotic resistance. In this study, we built a planar Gram-positive membrane-based biosensor that preserves the diversity of native membrane components using bacterial membrane vesicles. This biomembrane-based sensor, compatible with common surfaces such as glass, quartz crystals, and polymeric electrodes, facilitates the multimodal assessment of drug–membrane interactions. By recapitulating the established interaction patterns of the antimicrobial compound daptomycin, we demonstrated the successful biophysical characterization of interactions between this membrane-acting compound and the Gram-positive membrane. View this paper
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12 pages, 6340 KiB  
Communication
A Multimode Microfiber Specklegram Biosensor for Measurement of CEACAM5 through AI Diagnosis
by Yuhui Liu, Weihao Lin, Fang Zhao, Yibin Liu, Junhui Sun, Jie Hu, Jialong Li, Jinna Chen, Xuming Zhang, Mang I. Vai, Perry Ping Shum and Liyang Shao
Biosensors 2024, 14(1), 57; https://doi.org/10.3390/bios14010057 - 22 Jan 2024
Cited by 2 | Viewed by 1488
Abstract
Carcinoembryonic antigen (CEACAM5), as a broad-spectrum tumor biomarker, plays a crucial role in analyzing the therapeutic efficacy and progression of cancer. Herein, we propose a novel biosensor based on specklegrams of tapered multimode fiber (MMF) and two-dimensional convolutional neural networks (2D-CNNs) for the [...] Read more.
Carcinoembryonic antigen (CEACAM5), as a broad-spectrum tumor biomarker, plays a crucial role in analyzing the therapeutic efficacy and progression of cancer. Herein, we propose a novel biosensor based on specklegrams of tapered multimode fiber (MMF) and two-dimensional convolutional neural networks (2D-CNNs) for the detection of CEACAM5. The microfiber is modified with CEA antibodies to specifically recognize antigens. The biosensor utilizes the interference effect of tapered MMF to generate highly sensitive specklegrams in response to different CEACAM5 concentrations. A zero mean normalized cross-correlation (ZNCC) function is explored to calculate the image matching degree of the specklegrams. Profiting from the extremely high detection limit of the speckle sensor, variations in the specklegrams of antibody concentrations from 1 to 1000 ng/mL are measured in the experiment. The surface sensitivity of the biosensor is 0.0012 (ng/mL)−1 within a range of 1 to 50 ng/mL. Moreover, a 2D-CNN was introduced to solve the problem of nonlinear detection surface sensitivity variation in a large dynamic range, and in the search for image features to improve evaluation accuracy, achieving more accurate CEACAM5 monitoring, with a maximum detection error of 0.358%. The proposed fiber specklegram biosensing scheme is easy to implement and has great potential in analyzing the postoperative condition of patients. Full article
(This article belongs to the Special Issue Advanced Optical Fiber Sensors for Chemical and Biological Detection)
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17 pages, 2581 KiB  
Article
Sensing Levofloxacin with an RNA Aptamer as a Bioreceptor
by Janice Kramat, Leon Kraus, Vincent J. Gunawan, Elias Smyej, Philipp Froehlich, Tim E. Weber, Dieter Spiehl, Heinz Koeppl, Andreas Blaeser and Beatrix Suess
Biosensors 2024, 14(1), 56; https://doi.org/10.3390/bios14010056 - 22 Jan 2024
Viewed by 1775
Abstract
To combat the growing threat of antibiotic resistance, environmental testing for antibiotic contamination is gaining an increasing role. This study aims to develop an easy-to-use assay for the detection of the fluoroquinolone antibiotic levofloxacin. Levofloxacin is used in human and veterinary medicine and [...] Read more.
To combat the growing threat of antibiotic resistance, environmental testing for antibiotic contamination is gaining an increasing role. This study aims to develop an easy-to-use assay for the detection of the fluoroquinolone antibiotic levofloxacin. Levofloxacin is used in human and veterinary medicine and has been detected in wastewater and river water. An RNA aptamer against levofloxacin was selected using RNA Capture-SELEX. The 73 nt long aptamer folds into three stems with a central three-way junction. It binds levofloxacin with a Kd of 6 µM and discriminates the closely related compound ciprofloxacin. Furthermore, the selection process was analyzed using a next-generation sequencing approach to better understand the sequence evolution throughout the selection. The aptamer was used as a bioreceptor for the development of a lateral flow assay. The biosensor exploited the innate characteristic of RNA Capture-SELEX to select aptamers that displace a complementary DNA oligonucleotide upon ligand binding. The lateral flow assay achieved a limit of visual detection of 100 µM. While the sensitivity of this assay constrains its immediate use in environmental testing, the present study can serve as a template for the selection of RNA aptamer-based biosensors. Full article
(This article belongs to the Section Biosensors and Healthcare)
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24 pages, 5732 KiB  
Review
Microfluidics in High-Throughput Drug Screening: Organ-on-a-Chip and C. elegans-Based Innovations
by Sunhee Yoon, Dilara Kilicarslan You, Uiechan Jeong, Mina Lee, Eunhye Kim, Tae-Joon Jeon and Sun Min Kim
Biosensors 2024, 14(1), 55; https://doi.org/10.3390/bios14010055 - 21 Jan 2024
Cited by 1 | Viewed by 2589
Abstract
The development of therapeutic interventions for diseases necessitates a crucial step known as drug screening, wherein potential substances with medicinal properties are rigorously evaluated. This process has undergone a transformative evolution, driven by the imperative need for more efficient, rapid, and high-throughput screening [...] Read more.
The development of therapeutic interventions for diseases necessitates a crucial step known as drug screening, wherein potential substances with medicinal properties are rigorously evaluated. This process has undergone a transformative evolution, driven by the imperative need for more efficient, rapid, and high-throughput screening platforms. Among these, microfluidic systems have emerged as the epitome of efficiency, enabling the screening of drug candidates with unprecedented speed and minimal sample consumption. This review paper explores the cutting-edge landscape of microfluidic-based drug screening platforms, with a specific emphasis on two pioneering approaches: organ-on-a-chip and C. elegans-based chips. Organ-on-a-chip technology harnesses human-derived cells to recreate the physiological functions of human organs, offering an invaluable tool for assessing drug efficacy and toxicity. In parallel, C. elegans-based chips, boasting up to 60% genetic homology with humans and a remarkable affinity for microfluidic systems, have proven to be robust models for drug screening. Our comprehensive review endeavors to provide readers with a profound understanding of the fundamental principles, advantages, and challenges associated with these innovative drug screening platforms. We delve into the latest breakthroughs and practical applications in this burgeoning field, illuminating the pivotal role these platforms play in expediting drug discovery and development. Furthermore, we engage in a forward-looking discussion to delineate the future directions and untapped potential inherent in these transformative technologies. Through this review, we aim to contribute to the collective knowledge base in the realm of drug screening, providing valuable insights to researchers, clinicians, and stakeholders alike. We invite readers to embark on a journey into the realm of microfluidic-based drug screening platforms, fostering a deeper appreciation for their significance and promising avenues yet to be explored. Full article
(This article belongs to the Special Issue Advanced Microfluidic Devices and Lab-on-Chip (Bio)sensors)
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17 pages, 2840 KiB  
Article
Engineering and Characterization of 3-Aminotyrosine-Derived Red Fluorescent Variants of Circularly Permutated Green Fluorescent Protein
by Hao Zhang, Xiaodong Tian, Jing Zhang and Hui-wang Ai
Biosensors 2024, 14(1), 54; https://doi.org/10.3390/bios14010054 - 20 Jan 2024
Viewed by 1540
Abstract
Introducing 3-aminotyrosine (aY), a noncanonical amino acid (ncAA), into green fluorescent protein (GFP)-like chromophores shows promise for achieving red-shifted fluorescence. However, inconsistent results, including undesired green fluorescent species, hinder the effectiveness of this approach. In this study, we optimized expression conditions for an [...] Read more.
Introducing 3-aminotyrosine (aY), a noncanonical amino acid (ncAA), into green fluorescent protein (GFP)-like chromophores shows promise for achieving red-shifted fluorescence. However, inconsistent results, including undesired green fluorescent species, hinder the effectiveness of this approach. In this study, we optimized expression conditions for an aY-derived cpGFP (aY-cpGFP). Key factors like rich culture media and oxygen restriction pre- and post-induction enabled high-yield, high-purity production of the red-shifted protein. We also engineered two variants of aY-cpGFP with enhanced brightness by mutating a few amino acid residues surrounding the chromophore. We further investigated the sensitivity of the aY-derived protein to metal ions, reactive oxygen species (ROS), and reactive nitrogen species (RNS). Incorporating aY into cpGFP had minimal impact on metal ion reactivity but increased the response to RNS. Expanding on these findings, we examined aY-cpGFP expression in mammalian cells and found that reductants in the culture media significantly increased the red-emitting product. Our study indicates that optimizing expression conditions to promote a reduced cellular state proved effective in producing the desired red-emitting product in both E. coli and mammalian cells, while targeted mutagenesis-based protein engineering can further enhance brightness and increase method robustness. Full article
(This article belongs to the Special Issue Trends in Fluorescent and Bioluminescent Biosensors)
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16 pages, 933 KiB  
Article
Reagentless Vis-NIR Spectroscopy Point-of-Care for Feline Total White Blood Cell Counts
by Teresa Guerra Barroso, Carla Queirós, Filipe Monteiro-Silva, Filipe Santos, António Hugo Gregório and Rui Costa Martins
Biosensors 2024, 14(1), 53; https://doi.org/10.3390/bios14010053 - 19 Jan 2024
Viewed by 1605
Abstract
Spectral point-of-care technology is reagentless with minimal sampling (<10 μL) and can be performed in real-time. White blood cells are non-dominant in blood and in spectral information, suffering significant interferences from dominant constituents such as red blood cells, hemoglobin and billirubin. White blood [...] Read more.
Spectral point-of-care technology is reagentless with minimal sampling (<10 μL) and can be performed in real-time. White blood cells are non-dominant in blood and in spectral information, suffering significant interferences from dominant constituents such as red blood cells, hemoglobin and billirubin. White blood cells of a bigger size can account for 0.5% to 22.5% of blood spectra information. Knowledge expansion was performed using data augmentation through the hybridization of 94 real-world blood samples into 300 synthetic data samples. Synthetic data samples are representative of real-world data, expanding the detailed spectral information through sample hybridization, allowing us to unscramble the spectral white blood cell information from spectra, with correlations of 0.7975 to 0.8397 and a mean absolute error of 32.25% to 34.13%; furthermore, we achieved a diagnostic efficiency between 83% and 100% inside the reference interval (5.5 to 19.5 × 109 cell/L), and 85.11% for cases with extreme high white blood cell counts. At the covariance mode level, white blood cells are quantified using orthogonal information on red blood cells, maximizing sensitivity and specificity towards white blood cells, and avoiding the use of non-specific natural correlations present in the dataset; thus, the specifity of white blood cells spectral information is increased. The presented research is a step towards high-specificity, reagentless, miniaturized spectral point-of-care hematology technology for Veterinary Medicine. Full article
(This article belongs to the Section Optical and Photonic Biosensors)
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14 pages, 764 KiB  
Article
Exploring the Hidden Complexity: Entropy Analysis in Pulse Oximetry of Female Athletes
by Ana M. Cabanas, Macarena Fuentes-Guajardo, Nicolas Sáez, Davidson D. Catalán, Patricio O. Collao-Caiconte and Pilar Martín-Escudero
Biosensors 2024, 14(1), 52; https://doi.org/10.3390/bios14010052 - 19 Jan 2024
Viewed by 1290
Abstract
This study examines the relationship between physiological complexity, as measured by Approximate Entropy (ApEn) and Sample Entropy (SampEn), and fitness levels in female athletes. Our focus is on their association with maximal oxygen consumption (VO2,max). [...] Read more.
This study examines the relationship between physiological complexity, as measured by Approximate Entropy (ApEn) and Sample Entropy (SampEn), and fitness levels in female athletes. Our focus is on their association with maximal oxygen consumption (VO2,max). Our findings reveal a complex relationship between entropy metrics and fitness levels, indicating that higher fitness typically, though not invariably, correlates with greater entropy in physiological time series data; however, this is not consistent for all individuals. For Heart Rate (HR), entropy measures suggest stable patterns across fitness categories, while pulse oximetry (SpO2) data shows greater variability. For instance, the medium fitness group displayed an ApEn(HR) = 0.57±0.13 with a coefficient of variation (CV) of 22.17 and ApEn(SpO2) = 0.96±0.49 with a CV of 46.08%, compared to the excellent fitness group with ApEn(HR) = 0.60±0.09 with a CV of 15.19% and ApEn(SpO2) =0.85±0.42 with a CV of 49.46%, suggesting broader physiological responses among more fit individuals. The larger standard deviations and CVs for SpO2 entropy may indicate the body’s proficient oxygen utilization at higher levels of physical demand. Our findings advocate for combining entropy metrics with wearable sensor technology for improved biomedical analysis and personalized healthcare. Full article
(This article belongs to the Special Issue Wearable Biofluid Monitoring Sensors and Devices)
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12 pages, 4716 KiB  
Communication
A New Phenothiazine-Based Fluorescent Sensor for Detection of Cyanide
by Yulei Li, Chen Zhou, Jiaxin Li and Jing Sun
Biosensors 2024, 14(1), 51; https://doi.org/10.3390/bios14010051 - 18 Jan 2024
Cited by 1 | Viewed by 1328
Abstract
A new fluorescent sensor for the detection of CN was developed based on the conjugation of phenothiazine fluorophore and benzofuran unit. By the nucleophilic attacking of CN to the fluoroacetylamino group in the sensor, the additional reaction of CN and [...] Read more.
A new fluorescent sensor for the detection of CN was developed based on the conjugation of phenothiazine fluorophore and benzofuran unit. By the nucleophilic attacking of CN to the fluoroacetylamino group in the sensor, the additional reaction of CN and carbonyl group induced the ICT (intramolecular charge transfer) effect in the molecule and caused the fluorescence quenching sensor. The titration experiments show that the sensor has good sensitivity, selectivity and quick response for CN. In addition, the fluorescent detection of CN in the living cell and zebrafish experiments demonstrated the value of the sensor in tracing the CN in biological systems. Full article
(This article belongs to the Special Issue Nanoprobes for Biomedical Applications)
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14 pages, 3709 KiB  
Article
An All-in-One Platform for On-Site Multiplex Foodborne Pathogen Detection Based on Channel-Digital Hybrid Microfluidics
by Mei Xie, Tianlan Chen, Zongwei Cai, Bo Lei and Cheng Dong
Biosensors 2024, 14(1), 50; https://doi.org/10.3390/bios14010050 - 18 Jan 2024
Viewed by 1507
Abstract
Recently, significant progress has been made in the development of microdevices for point-of-care infectious disease detection. However, most microdevices only allow limited steps, such as DNA amplification on the chip, while sample preparation, such as lysis and DNA extraction, is conducted off the [...] Read more.
Recently, significant progress has been made in the development of microdevices for point-of-care infectious disease detection. However, most microdevices only allow limited steps, such as DNA amplification on the chip, while sample preparation, such as lysis and DNA extraction, is conducted off the chip using the traditional method. In this study, an all-in-one platform was developed, which incorporated all necessary procedures for nucleic acid detection. Our on-chip DNA extraction method utilized the magnetic bead-based technology on a hybrid channel-digital microfluidics (C-DMF) microdevice. It yielded high recovery rates, varying from 88.43% to 95.83%, with pathogen concentrations of 103–106 CFU/mL. In particular, the on-chip method exhibited significantly higher efficacy compared to the traditional off-chip manual method, for the DNA extraction of E. coli and S. aureus, representing Gram-negative and Gram-positive bacteria, respectively, at a sample concentration of 103 CFU/mL. To address the need for rapid and accessible diagnostics, colorimetric LAMP amplification was integrated into the proposed microdevice. The results were visually detectable with the naked eye, making it user-friendly for non-specialists. In addition, this platform demonstrated impressive sensitivity in simultaneously detecting common foodborne pathogens in spiked meat samples, achieving the LOD of 102–103 CFU/mL. The entire process, from sampling to result, was fully automated and only required approximately 60 min, offering promising applicability in resource-limited and on-site testing scenarios. Full article
(This article belongs to the Special Issue Electrochemical Biosensing Platforms for Food, Drug and Health Safety)
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14 pages, 5581 KiB  
Article
Aggregation-Resistant, Turn-On-Off Fluorometric Sensing of Glutathione and Nickel (II) Using Vancomycin-Conjugated Gold Nanoparticles
by Atul Kumar Tiwari, Munesh Kumar Gupta, Hari Prakash Yadav, Roger J. Narayan and Prem C. Pandey
Biosensors 2024, 14(1), 49; https://doi.org/10.3390/bios14010049 - 16 Jan 2024
Cited by 1 | Viewed by 1551
Abstract
Glutathione (GSH) and nickel (II) cation have an indispensable role in various physiological processes, including preventing the oxidative damage of cells and acting as a cofactor for lipid metabolic enzymes. An imbalance in the physiological level of these species may cause serious health [...] Read more.
Glutathione (GSH) and nickel (II) cation have an indispensable role in various physiological processes, including preventing the oxidative damage of cells and acting as a cofactor for lipid metabolic enzymes. An imbalance in the physiological level of these species may cause serious health complications. Therefore, sensitive and selective fluorescent probes for the detection of GSH and nickel (II) are of great interest for clinical as well as environmental monitoring. Herein, vancomycin-conjugated gold nanoparticles (PEI-AuNP@Van) were prepared and employed for the detection of GSH and nickel (II) based on a turn-on-off mechanism. The as-synthesized PEI-AuNP@Van was ~7.5 nm in size; it exhibited a spherical shape with face-centered cubic lattice symmetry. As compared to vancomycin unconjugated gold nanoparticles, GSH led to the turn-on state of PEI-AuNP@Van, while Ni2+ acted as a fluorescence quencher (turn-off) without the aggregation of nanoparticles. These phenomena strongly justify the active role of vancomycin conjugation for the detection of GSH and Ni2+. The turn-on-off kinetics was linearly proportional over the concentration range between 0.05–0.8 µM and 0.05–6.4 μM. The detection limits were 205.9 and 90.5 nM for GSH and Ni2+, respectively; these results are excellent in comparison to previous reports. This study demonstrates the active role of vancomycin conjugation for sensing of GSH and Ni2+ along with PEI-AuNP@Van as a promising nanoprobe. Full article
(This article belongs to the Special Issue Biosensor Nanoengineering: Design, Operation and Implementation)
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15 pages, 2247 KiB  
Article
A Path towards Timely VAP Diagnosis: Proof-of-Concept Study on Pyocyanin Sensing with Cu-Mg Doped Graphene Oxide
by Mohammad Noorizadeh, Mithra Geetha, Faycal Bensaali, Nader Meskin, Kishor K. Sadasivuni, Susu M. Zughaier, Mahmoud Elgamal and Ali Ait Hssain
Biosensors 2024, 14(1), 48; https://doi.org/10.3390/bios14010048 - 16 Jan 2024
Viewed by 1456
Abstract
In response to the urgent requirement for rapid, precise, and cost-effective detection in intensive care units (ICUs) for ventilated patients, as well as the need to overcome the limitations of traditional detection methods, researchers have turned their attention towards advancing novel technologies. Among [...] Read more.
In response to the urgent requirement for rapid, precise, and cost-effective detection in intensive care units (ICUs) for ventilated patients, as well as the need to overcome the limitations of traditional detection methods, researchers have turned their attention towards advancing novel technologies. Among these, biosensors have emerged as a reliable platform for achieving accurate and early diagnoses. In this study, we explore the possibility of using Pyocyanin analysis for early detection of pathogens in ventilator-associated pneumonia (VAP) and lower respiratory tract infections in ventilated patients. To achieve this, we developed an electrochemical sensor utilizing a graphene oxide–copper oxide-doped MgO (GOCuMgo) (GCM) catalyst for Pyocyanin detection. Pyocyanin is a virulence factor in the phenazine group that is produced by Pseudomonas aeruginosa strains, leading to infections such as pneumonia, urinary tract infections, and cystic fibrosis. We additionally investigated the use of DNA aptamers for detecting Pyocyanin as a biomarker of Pseudomonas aeruginosa, a common causative agent of VAP. The results of this study indicated that electrochemical detection of Pyocyanin using a GCM catalyst shows promising potential for various applications, including clinical diagnostics and drug discovery. Full article
(This article belongs to the Special Issue Electrochemical Sensors and Biosensors for Biomedical Applications)
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10 pages, 1525 KiB  
Article
Aptamer-Based Switching System for Communication of Non-Interacting Proteins
by Younghyeon Kim, Daehan Nam, Eun Sung Lee, Seokjoon Kim, Byung Seok Cha and Ki Soo Park
Biosensors 2024, 14(1), 47; https://doi.org/10.3390/bios14010047 - 16 Jan 2024
Cited by 1 | Viewed by 1460
Abstract
Biological macromolecules, such as DNA, RNA, and proteins in living organisms, form an intricate network that plays a key role in many biological processes. Many attempts have been made to build new networks by connecting non-communicable proteins with network mediators, especially using antibodies. [...] Read more.
Biological macromolecules, such as DNA, RNA, and proteins in living organisms, form an intricate network that plays a key role in many biological processes. Many attempts have been made to build new networks by connecting non-communicable proteins with network mediators, especially using antibodies. In this study, we devised an aptamer-based switching system that enables communication between non-interacting proteins. As a proof of concept, two proteins, Cas13a and T7 RNA polymerase (T7 RNAP), were rationally connected using an aptamer that specifically binds to T7 RNAP. The proposed switching system can be modulated in both signal-on and signal-off manners and its responsiveness to the target activator can be controlled by adjusting the reaction time. This study paves the way for the expansion of biological networks by mediating interactions between proteins using aptamers. Full article
(This article belongs to the Special Issue CRISPR/Cas-Based Biosensing Systems: Development and Applications)
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30 pages, 7707 KiB  
Review
Recent Advances in Electrochemical Detection of Cell Energy Metabolism
by Kyeong-Mo Koo, Chang-Dae Kim and Tae-Hyung Kim
Biosensors 2024, 14(1), 46; https://doi.org/10.3390/bios14010046 - 15 Jan 2024
Viewed by 2221
Abstract
Cell energy metabolism is a complex and multifaceted process by which some of the most important nutrients, particularly glucose and other sugars, are transformed into energy. This complexity is a result of dynamic interactions between multiple components, including ions, metabolic intermediates, and products [...] Read more.
Cell energy metabolism is a complex and multifaceted process by which some of the most important nutrients, particularly glucose and other sugars, are transformed into energy. This complexity is a result of dynamic interactions between multiple components, including ions, metabolic intermediates, and products that arise from biochemical reactions, such as glycolysis and mitochondrial oxidative phosphorylation (OXPHOS), the two main metabolic pathways that provide adenosine triphosphate (ATP), the main source of chemical energy driving various physiological activities. Impaired cell energy metabolism and perturbations or dysfunctions in associated metabolites are frequently implicated in numerous diseases, such as diabetes, cancer, and neurodegenerative and cardiovascular disorders. As a result, altered metabolites hold value as potential disease biomarkers. Electrochemical biosensors are attractive devices for the early diagnosis of many diseases and disorders based on biomarkers due to their advantages of efficiency, simplicity, low cost, high sensitivity, and high selectivity in the detection of anomalies in cellular energy metabolism, including key metabolites involved in glycolysis and mitochondrial processes, such as glucose, lactate, nicotinamide adenine dinucleotide (NADH), reactive oxygen species (ROS), glutamate, and ATP, both in vivo and in vitro. This paper offers a detailed examination of electrochemical biosensors for the detection of glycolytic and mitochondrial metabolites, along with their many applications in cell chips and wearable sensors. Full article
(This article belongs to the Special Issue Cell-Based Biosensors for Rapid Detection and Monitoring)
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21 pages, 3152 KiB  
Article
Gram-Positive Bacterial Membrane-Based Biosensor for Multimodal Investigation of Membrane–Antibiotic Interactions
by Samavi Farnush Bint-E-Naser, Zeinab Jushkun Mohamed, Zhongmou Chao, Karan Bali, Róisín M. Owens and Susan Daniel
Biosensors 2024, 14(1), 45; https://doi.org/10.3390/bios14010045 - 15 Jan 2024
Viewed by 1832
Abstract
As membrane-mediated antibiotic resistance continues to evolve in Gram-positive bacteria, the development of new approaches to elucidate the membrane properties involved in antibiotic resistance has become critical. Membrane vesicles (MVs) secreted by the cytoplasmic membrane of Gram-positive bacteria contain native components, preserving lipid [...] Read more.
As membrane-mediated antibiotic resistance continues to evolve in Gram-positive bacteria, the development of new approaches to elucidate the membrane properties involved in antibiotic resistance has become critical. Membrane vesicles (MVs) secreted by the cytoplasmic membrane of Gram-positive bacteria contain native components, preserving lipid and protein diversity, nucleic acids, and sometimes virulence factors. Thus, MV-derived membrane platforms present a great model for Gram-positive bacterial membranes. In this work, we report the development of a planar bacterial cytoplasmic membrane-based biosensor using MVs isolated from the Bacillus subtilis WT strain that can be coated on multiple surface types such as glass, quartz crystals, and polymeric electrodes, fostering the multimodal assessment of drug–membrane interactions. Retention of native membrane components such as lipoteichoic acids, lipids, and proteins is verified. This biosensor replicates known interaction patterns of the antimicrobial compound, daptomycin, with the Gram-positive bacterial membrane, establishing the applicability of this platform for carrying out biophysical characterization of the interactions of membrane-acting antibiotic compounds with the bacterial cytoplasmic membrane. We report changes in membrane viscoelasticity and permeability that correspond to partial membrane disruption when calcium ions are present with daptomycin but not when these ions are absent. This biomembrane-based biosensing platform enables an assessment of membrane biophysical characteristics during exposure to antibiotic drug candidates to aid in identifying compounds that target membrane disruption as a mechanism of action. Full article
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10 pages, 2451 KiB  
Communication
Transitional Electrodes in Electrowetting-Based Droplet Dispensing
by Wei Wang, Qijun Cai, Shangzhe Xu and Xucan Chen
Biosensors 2024, 14(1), 44; https://doi.org/10.3390/bios14010044 - 14 Jan 2024
Viewed by 1265
Abstract
Digital microfluidic systems based on electrowetting-on-dielectric technology, particularly valuable in producing and manipulating microdroplets steadily and consistently, have experienced notable advancements in recent years. In this paper, experimental characterizations reveal that simply adding one transitional electrode between the reservoir and the splitting electrode [...] Read more.
Digital microfluidic systems based on electrowetting-on-dielectric technology, particularly valuable in producing and manipulating microdroplets steadily and consistently, have experienced notable advancements in recent years. In this paper, experimental characterizations reveal that simply adding one transitional electrode between the reservoir and the splitting electrode improves the volumetric consistency and reproducibility for droplet dispensing. The volumetric coefficient variation of the consecutively dispensed droplets from a non-refilling reservoir decreases by 1% after the addition of one transitional electrode, with no extra external apparatus. This work provides a straightforward yet effective approach to the improvement of digital microfluidic systems and micro total analysis systems. Full article
(This article belongs to the Special Issue Biosensor Nanoengineering: Design, Operation and Implementation)
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14 pages, 2762 KiB  
Article
Photonic Crystal Surface Mode Real-Time Imaging of RAD51 DNA Repair Protein Interaction with the ssDNA Substrate
by Galina Nifontova, Cathy Charlier, Nizar Ayadi, Fabrice Fleury, Alexander Karaulov, Alyona Sukhanova and Igor Nabiev
Biosensors 2024, 14(1), 43; https://doi.org/10.3390/bios14010043 - 14 Jan 2024
Viewed by 1809
Abstract
Photonic crystals (PCs) are promising tools for label-free sensing in drug discovery screening, diagnostics, and analysis of ligand–receptor interactions. Imaging of PC surface modes has emerged as a novel approach to the detection of multiple binding events at the sensor surface. PC surface [...] Read more.
Photonic crystals (PCs) are promising tools for label-free sensing in drug discovery screening, diagnostics, and analysis of ligand–receptor interactions. Imaging of PC surface modes has emerged as a novel approach to the detection of multiple binding events at the sensor surface. PC surface modification and decoration with recognition units yield an interface providing the highly sensitive detection of cancer biomarkers, antibodies, and oligonucleotides. The RAD51 protein plays a central role in DNA repair via the homologous recombination pathway. This recombinase is essential for the genome stability and its overexpression is often correlated with aggressive cancer. RAD51 is therefore a potential target in the therapeutic strategy for cancer. Here, we report the designing of a PC-based array sensor for real-time monitoring of oligonucleotide–RAD51 recruitment by means of surface mode imaging and validation of the concept of this approach. Our data demonstrate that the designed biosensor ensures the highly sensitive multiplexed analysis of association–dissociation events and detection of the biomarker of DNA damage using a microfluidic PC array. The obtained results highlight the potential of the developed technique for testing the functionality of candidate drugs, discovering new molecular targets and drug entities. This paves the way to further adaption and bioanalytical use of the biosensor for high-content screening to identify new DNA repair inhibitor drugs targeting the RAD51 nucleoprotein filament or to discover new molecular targets. Full article
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11 pages, 2468 KiB  
Article
Effects of Game-Related Tasks for the Diagnosis and Classification of Gaming Disorder
by Jeongbong Choi, Youngseok Choi, Young-Chul Jung, Jeyeon Lee, Jongshill Lee, Eunkyoung Park and In Young Kim
Biosensors 2024, 14(1), 42; https://doi.org/10.3390/bios14010042 - 13 Jan 2024
Viewed by 1477
Abstract
Gaming disorder (GD) is an addictive behavior characterized by an insatiable need to play video games and shares similar symptoms with the failure of self-control due to a decline in cognitive function. Current GD diagnostic and screening tools rely on questionnaires and behavioral [...] Read more.
Gaming disorder (GD) is an addictive behavior characterized by an insatiable need to play video games and shares similar symptoms with the failure of self-control due to a decline in cognitive function. Current GD diagnostic and screening tools rely on questionnaires and behavioral observations related to cognitive functions to assess an individual’s capacity to maintain self-control in everyday life. However, current GD screening approaches rely on subjective symptoms, and a reliable diagnosis requires long-term clinical follow-up. Recent studies have measured biosignals along with cognitive functional tasks to provide objectivity to GD diagnosis and to acquire immediate results. However, people with GD are hypersensitive to game-related cues, so their responses may vary depending on the type of stimuli, and the difference in response to stimuli might manifest as a difference in the degree of change in the biosignal. Therefore, it is critical to choose the correct stimulus type when performing GD diagnostic tasks. In this study, we investigated the task dependence of cognitive decline in GD by comparing two cognitive functional tasks: a continuous performance task (CPT) and video game play. For this study, 69 young male adults were classified into either the gaming disorder group (GD, n = 39) or a healthy control group (HC, n = 30). CPT score, EEG signal (theta, alpha, and beta), and HRV-HF power were assessed. We observed differences in the left frontal region (LF) of the brain between the GD and HC groups during online video game play. The GD group also showed a significant difference in HF power of HRV between CPT and online video gaming. Furthermore, LF and HRV-HF significantly correlated with Young’s Internet Addiction Test (Y-IAT) score, which is positively associated with impulsivity score. The amount of change in theta band activity in LF and HRV-HF—both biomarkers for changes in cognitive function—during online video game play suggests that people with GD express task-dependent cognitive decline compared with HC. Our results demonstrate the feasibility of quantifying individual self-regulation ability for gaming and underscore its importance for GD classification. Full article
(This article belongs to the Section Biosensors and Healthcare)
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15 pages, 9504 KiB  
Article
Understanding DNA Epigenetics by Means of Raman/SERS Analysis for Cancer Detection
by Luca David, Anca Onaciu, Valentin Toma, Rareș-Mario Borșa, Cristian Moldovan, Adrian-Bogdan Țigu, Diana Cenariu, Ioan Șimon, Gabriela-Fabiola Știufiuc, Eugen Carasevici, Brîndușa Drăgoi, Ciprian Tomuleasa and Rareș-Ionuț Știufiuc
Biosensors 2024, 14(1), 41; https://doi.org/10.3390/bios14010041 - 12 Jan 2024
Viewed by 1482
Abstract
This study delves into the intricate interaction between DNA and nanosystems, exploring its potential implications for biomedical applications. The focus lies in understanding the adsorption geometry of DNA when in proximity to plasmonic nanoparticles, utilizing ultrasensitive vibrational spectroscopy techniques. Employing a combined Raman-SERS [...] Read more.
This study delves into the intricate interaction between DNA and nanosystems, exploring its potential implications for biomedical applications. The focus lies in understanding the adsorption geometry of DNA when in proximity to plasmonic nanoparticles, utilizing ultrasensitive vibrational spectroscopy techniques. Employing a combined Raman-SERS analysis, we conducted an in-depth examination to clarify the molecular geometry of interactions between DNA and silver nanoparticles. Our findings also reveal distinctive spectral features regarding DNA samples due to their distinctive genome stability. To understand the subtle differences occurring between normal and cancerous DNA, their thermal stability was investigated by means of SERS measurement performed before and after a thermal treatment at 94 °C. It was proved that thermal treatment did not affect DNA integrity in the case of normal cells. On the other hand, due to epimutation pattern that characterizes cancerous DNA, variations between spectra recorded before and after heat treatment were observed, suggesting genome instability. These findings highlight the potential of DNA analysis using SERS for cancer detection. They demonstrate the applicability of this approach to overcoming challenges associated with low DNA concentrations (e.g., circulating tumor DNA) that occur in biofluids. In conclusion, this research contributes significant insights into the nanoscale behavior of DNA in the presence of nanosystems. Full article
(This article belongs to the Special Issue SERS-Based Biosensors: Design and Biomedical Applications)
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15 pages, 2700 KiB  
Review
Advances in the Application of Transition-Metal Composite Nanozymes in the Field of Biomedicine
by Huixin Wang, Chunfang Cheng, Jingyu Zhao, Fangqin Han, Guanhui Zhao, Yong Zhang and Yaoguang Wang
Biosensors 2024, 14(1), 40; https://doi.org/10.3390/bios14010040 - 12 Jan 2024
Cited by 2 | Viewed by 1501
Abstract
Due to the limitation that natural peroxidase enzymes can only function in relatively mild environments, nanozymes have expanded the application of enzymology in the biological field by dint of their ability to maintain catalytic oxidative activity in relatively harsh environments. At the same [...] Read more.
Due to the limitation that natural peroxidase enzymes can only function in relatively mild environments, nanozymes have expanded the application of enzymology in the biological field by dint of their ability to maintain catalytic oxidative activity in relatively harsh environments. At the same time, the development of new and highly efficient composite nanozymes has been a challenge due to the limitations of monometallic particles in applications and the inherently poor enzyme-mimetic activity of composite nanozymes. The inherent enzyme-mimicking activity is due to Au, Ag, and Pt, along with other transition metals. Moreover, the nanomaterials exhibit excellent enzyme-mimicking activity when composited with other materials. Therefore, this paper focuses on composite nanozymes with simulated peroxidase activity that have been prepared using noble metals such as Au, Ag, and Pt and other transition metal nanoparticles in recent years. Their simulated enzymatic activity is utilized for biomedical applications such as glucose detection, cancer cell detection and tumor treatment, and antibacterial applications. Full article
(This article belongs to the Section Nano- and Micro-Technologies in Biosensors)
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16 pages, 2304 KiB  
Review
Nanophotonic Enhanced Chiral Sensing and Its Biomedical Applications
by Fei Wang, Xue Wang, Xinchao Lu and Chengjun Huang
Biosensors 2024, 14(1), 39; https://doi.org/10.3390/bios14010039 - 12 Jan 2024
Viewed by 1683
Abstract
Chiral sensing is crucial in the fields of biology and the pharmaceutical industry. Many naturally occurring biomolecules, i.e., amino acids, sugars, and nucleotides, are inherently chiral. Their enantiomers are strongly associated with the pharmacological effects of chiral drugs. Owing to the extremely weak [...] Read more.
Chiral sensing is crucial in the fields of biology and the pharmaceutical industry. Many naturally occurring biomolecules, i.e., amino acids, sugars, and nucleotides, are inherently chiral. Their enantiomers are strongly associated with the pharmacological effects of chiral drugs. Owing to the extremely weak chiral light–matter interactions, chiral sensing at an optical frequency is challenging, especially when trace amounts of molecules are involved. The nanophotonic platform allows for a stronger interaction between the chiral molecules and light to enhance chiral sensing. Here, we review the recent progress in nanophotonic-enhanced chiral sensing, with a focus on the superchiral near-field and enhanced circular dichroism (CD) spectroscopy generated in both the dielectric and in plasmonic structures. In addition, the recent applications of chiral sensing in biomedical fields are discussed, including the detection and treatment of difficult diseases, i.e., Alzheimer’s disease, diabetes, and cancer. Full article
(This article belongs to the Special Issue Women in Biosensors (Volume II))
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12 pages, 1913 KiB  
Article
ZIF-67 Anchored on MoS2/rGO Heterostructure for Non-Enzymatic and Visible-Light-Sensitive Photoelectrochemical Biosensing
by Qiaolin Fan, Xiao Li, Hui Dong, Zhonghua Ni and Tao Hu
Biosensors 2024, 14(1), 38; https://doi.org/10.3390/bios14010038 - 12 Jan 2024
Cited by 2 | Viewed by 1452
Abstract
Graphene and graphene-like two-dimensional layered nanomaterials-based photoelectrochemical (PEC) biosensors have recently grown rapidly in popularity thanks to their advantages of high sensitivity and low background signal, which have attracted tremendous attention in ultrahigh sensitive small molecule detection. This work proposes a non-enzymatic and [...] Read more.
Graphene and graphene-like two-dimensional layered nanomaterials-based photoelectrochemical (PEC) biosensors have recently grown rapidly in popularity thanks to their advantages of high sensitivity and low background signal, which have attracted tremendous attention in ultrahigh sensitive small molecule detection. This work proposes a non-enzymatic and visible-light-sensitive PEC biosensing platform based on ZIF-67@MoS2/rGO composite which is synthesized through a facile and one-step microwave-assisted hydrothermal method. The combination of MoS2 and rGO could construct van der Waals heterostructures, which not only act as visible-light-active nanomaterials, but facilitate charge carriers transfer between the photoelectrode and glassy carbon electrode (GCE). ZIF-67 anchored on MoS2/rGO heterostructures provides large specific surface areas and a high proportion of catalytic sites, which cooperate with MoS2 nanosheets, realizing rapid and efficient enzyme-free electrocatalytic oxidation of glucose. The ZIF-67@MoS2/rGO-modified GCE can realize the rapid and sensitive detection of glucose at low detection voltage, which exhibits a high sensitivity of 12.62 μAmM−1cm−2. Finally, the ZIF-67@MoS2/rGO PEC biosensor is developed by integrating the ZIF-67@MoS2/rGO with a screen-printed electrode (SPE), which exhibits a high sensitivity of 3.479 μAmM−1cm−2 and a low detection limit of 1.39 μM. The biosensor’s selectivity, stability, and repeatability are systematically investigated, and its practicability is evaluated by detecting clinical serum samples. Full article
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13 pages, 2317 KiB  
Article
Rapid and Easy Detection of Microcystin-LR Using a Bioactivated Multi-Walled Carbon Nanotube-Based Field-Effect Transistor Sensor
by Myeongsoon Lee, Seong H. Kim, Don Kim and Hak Jun Kim
Biosensors 2024, 14(1), 37; https://doi.org/10.3390/bios14010037 - 11 Jan 2024
Viewed by 1269
Abstract
In this study, we developed a multi-walled carbon nanotube (MWCNT)-based field-effect transistor (MWCNT-FET) sensor with high sensitivity and selectivity for microcystin-LR (MC-LR). Carboxylated MWCNTs were activated with an MC-LR-targeting aptamer (MCTA). Subsequently the bioactivated MWCNTs were immobilized between interdigitated drain (D) and source [...] Read more.
In this study, we developed a multi-walled carbon nanotube (MWCNT)-based field-effect transistor (MWCNT-FET) sensor with high sensitivity and selectivity for microcystin-LR (MC-LR). Carboxylated MWCNTs were activated with an MC-LR-targeting aptamer (MCTA). Subsequently the bioactivated MWCNTs were immobilized between interdigitated drain (D) and source (S) electrodes through self-assembly. The top-gated MWCNT-FET sensor was configured by dropping the sample solution onto the D and S electrodes and immersing a Ag/AgCl electrode in the sample solution as a gate (G) electrode. We believe that the FET sensor’s conduction path arises from the interplay between the MCTAs, with the applied gate potential modulating this path. Using standard instruments and a personal computer, the sensor’s response was detected in real-time within a 10 min time frame. This label-free FET sensor demonstrated an impressive detection capability for MC-LR in the concentration range of 0.1–0.5 ng/mL, exhibiting a lower detection limit of 0.11 ng/mL. Additionally, the MWCNT-FET sensor displayed consistent reproducibility, a robust selectivity for MC-LR over its congeners, and minimal matrix interferences. Given these attributes, this easily mass-producible FET sensor is a promising tool for rapid, straightforward, and sensitive MC-LR detection in freshwater environments. Full article
(This article belongs to the Special Issue Field-Effect Transistor-Based Biosensors)
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17 pages, 3037 KiB  
Review
Recent Developments in Paper-Based Sensors with Instrument-Free Signal Readout Technologies (2020–2023)
by Danni Yang, Chengju Hu, Hao Zhang and Shan Geng
Biosensors 2024, 14(1), 36; https://doi.org/10.3390/bios14010036 - 11 Jan 2024
Cited by 1 | Viewed by 1370
Abstract
Signal readout technologies that do not require any instrument are essential for improving the convenience and availability of paper-based sensors. Thanks to the remarkable progress in material science and nanotechnology, paper-based sensors with instrument-free signal readout have been developed for multiple purposes, such [...] Read more.
Signal readout technologies that do not require any instrument are essential for improving the convenience and availability of paper-based sensors. Thanks to the remarkable progress in material science and nanotechnology, paper-based sensors with instrument-free signal readout have been developed for multiple purposes, such as biomedical detection, environmental pollutant tracking, and food analysis. In this review, the developments in instrument-free signal readout technologies for paper-based sensors from 2020 to 2023 are summarized. The instrument-free signal readout technologies, such as distance-based signal readout technology, counting-based signal readout technology, text-based signal readout technology, as well as other transduction technologies, are briefly introduced, respectively. On the other hand, the applications of paper-based sensors with instrument-free signal readout technologies are summarized, including biomedical analysis, environmental analysis, food analysis, and other applications. Finally, the potential and difficulties associated with the advancement of paper-based sensors without instruments are discussed. Full article
(This article belongs to the Special Issue Paper-Based Microfluidic Devices and Applications)
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22 pages, 1736 KiB  
Review
New Advances in Antenna Design toward Wearable Devices Based on Nanomaterials
by Chunge Wang, Ning Zhang, Chen Liu, Bangbang Ma, Keke Zhang, Rongzhi Li, Qianqian Wang and Sheng Zhang
Biosensors 2024, 14(1), 35; https://doi.org/10.3390/bios14010035 - 10 Jan 2024
Cited by 2 | Viewed by 2578
Abstract
Wearable antennas have recently garnered significant attention due to their attractive properties and potential for creating lightweight, compact, low-cost, and multifunctional wireless communication systems. With the breakthrough progress in nanomaterial research, the use of lightweight materials has paved the way for the widespread [...] Read more.
Wearable antennas have recently garnered significant attention due to their attractive properties and potential for creating lightweight, compact, low-cost, and multifunctional wireless communication systems. With the breakthrough progress in nanomaterial research, the use of lightweight materials has paved the way for the widespread application of wearable antennas. Compared with traditional metallic materials like copper, aluminum, and nickel, nanoscale entities including zero-dimensional (0-D) nanoparticles, one-dimensional (1-D) nanofibers or nanotubes, and two-dimensional (2-D) nanosheets exhibit superior physical, electrochemical, and performance characteristics. These properties significantly enhance the potential for constructing durable electronic composites. Furthermore, the antenna exhibits compact size and high deformation stability, accompanied by greater portability and wear resistance, owing to the high surface-to-volume ratio and flexibility of nanomaterials. This paper systematically discusses the latest advancements in wearable antennas based on 0-D, 1-D, and 2-D nanomaterials, providing a comprehensive overview of their development and future prospects in the field. Full article
(This article belongs to the Special Issue Recent Advances in Wearable Biosensors for Human Health Monitoring)
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13 pages, 5825 KiB  
Article
Detection of Sialic Acid to Differentiate Cervical Cancer Cell Lines Using a Sambucus nigra Lectin Biosensor
by Ricardo Zamudio Cañas, María Eugenia Jaramillo Flores, Verónica Vallejo Ruiz, Raúl Jacobo Delgado Macuil and Valentín López Gayou
Biosensors 2024, 14(1), 34; https://doi.org/10.3390/bios14010034 - 10 Jan 2024
Viewed by 1599
Abstract
Pap smear screening is a widespread technique used to detect premalignant lesions of cervical cancer (CC); however, it lacks sensitivity, leading to identifying biomarkers that improve early diagnosis sensitivity. A characteristic of cancer is the aberrant sialylation that involves the abnormal expression of [...] Read more.
Pap smear screening is a widespread technique used to detect premalignant lesions of cervical cancer (CC); however, it lacks sensitivity, leading to identifying biomarkers that improve early diagnosis sensitivity. A characteristic of cancer is the aberrant sialylation that involves the abnormal expression of α2,6 sialic acid, a specific carbohydrate linked to glycoproteins and glycolipids on the cell surface, which has been reported in premalignant CC lesions. This work aimed to develop a method to differentiate CC cell lines and primary fibroblasts using a novel lectin-based biosensor to detect α2,6 sialic acid based on attenuated total reflectance Fourier transform infrared spectroscopy (ATR-FTIR) and chemometric. The biosensor was developed by conjugating gold nanoparticles (AuNPs) with 5 µg of Sambucus nigra (SNA) lectin as the biorecognition element. Sialic acid detection was associated with the signal amplification in the 1500–1350 cm−1 region observed by the surface-enhanced infrared absorption spectroscopy (SEIRA) effect from ATR-FTIR results. This region was further analyzed for the clustering of samples by applying principal component analysis (PCA) and confidence ellipses at a 95% interval. This work demonstrates the feasibility of employing SNA biosensors to discriminate between tumoral and non-tumoral cells, that have the potential for the early detection of premalignant lesions of CC. Full article
(This article belongs to the Topic Machine Learning and Biomedical Sensors)
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13 pages, 1581 KiB  
Review
Advancing Brain Research through Surface-Enhanced Raman Spectroscopy (SERS): Current Applications and Future Prospects
by Suzan Elsheikh, Nathan P. Coles, Ojodomo J. Achadu, Panagiota S. Filippou and Ahmad A. Khundakar
Biosensors 2024, 14(1), 33; https://doi.org/10.3390/bios14010033 - 10 Jan 2024
Viewed by 2452
Abstract
Surface-enhanced Raman spectroscopy (SERS) has recently emerged as a potent analytical technique with significant potential in the field of brain research. This review explores the applications and innovations of SERS in understanding the pathophysiological basis and diagnosis of brain disorders. SERS holds significant [...] Read more.
Surface-enhanced Raman spectroscopy (SERS) has recently emerged as a potent analytical technique with significant potential in the field of brain research. This review explores the applications and innovations of SERS in understanding the pathophysiological basis and diagnosis of brain disorders. SERS holds significant advantages over conventional Raman spectroscopy, particularly in terms of sensitivity and stability. The integration of label-free SERS presents promising opportunities for the rapid, reliable, and non-invasive diagnosis of brain-associated diseases, particularly when combined with advanced computational methods such as machine learning. SERS has potential to deepen our understanding of brain diseases, enhancing diagnosis, monitoring, and therapeutic interventions. Such advancements could significantly enhance the accuracy of clinical diagnosis and further our understanding of brain-related processes and diseases. This review assesses the utility of SERS in diagnosing and understanding the pathophysiological basis of brain disorders such as Alzheimer’s and Parkinson’s diseases, stroke, and brain cancer. Recent technological advances in SERS instrumentation and techniques are discussed, including innovations in nanoparticle design, substrate materials, and imaging technologies. We also explore prospects and emerging trends, offering insights into new technologies, while also addressing various challenges and limitations associated with SERS in brain research. Full article
(This article belongs to the Special Issue SERS-Based Biosensors: Design and Biomedical Applications)
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17 pages, 10492 KiB  
Article
Shielded Cone Coil Array for Non-Invasive Deep Brain Magnetic Stimulation
by Rawan Abu Yosef, Kamel Sultan, Ahmed Toaha Mobashsher, Firuz Zare, Paul C. Mills and Amin Abbosh
Biosensors 2024, 14(1), 32; https://doi.org/10.3390/bios14010032 - 9 Jan 2024
Viewed by 1640
Abstract
Non-invasive deep brain stimulation using transcranial magnetic stimulation is a promising technique for treating several neurological disorders, such as Alzheimer’s and Parkinson’s diseases. However, the currently used coils do not demonstrate the required stimulation performance in deep regions of the brain, such as [...] Read more.
Non-invasive deep brain stimulation using transcranial magnetic stimulation is a promising technique for treating several neurological disorders, such as Alzheimer’s and Parkinson’s diseases. However, the currently used coils do not demonstrate the required stimulation performance in deep regions of the brain, such as the hippocampus, due to the rapid decay of the field inside the head. This study proposes an array that uses the cone coil method for deep stimulation. This study investigates the impact of magnetic core and shielding on field strength, focality, decay rate, and safety. The coil’s size and shape effects on the electric field distribution in deep brain areas are also examined. The finite element method is used to calculate the induced electric field in a realistic human head model. The simulation results indicate that the magnetic core and shielding increase the electric field intensity and enhance focality but do not improve the field decay rate. However, the decay rate can be reduced by increasing the coil size at the expense of focality. By adopting an optimum cone structure, the proposed five-coil array reduces the electric field attenuation rate to reach the stimulation threshold in deep regions while keeping all other regions within safety limits. In vitro and in vivo experimental results using a head phantom and a dead pig’s head validate the simulated results and confirm that the proposed design is a reliable and efficient candidate for non-invasive deep brain magnetic stimulation. Full article
(This article belongs to the Special Issue Biosensing, Biosafety and Diagnosis)
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18 pages, 7260 KiB  
Article
System of Implantable Electrodes for Neural Signal Acquisition and Stimulation for Wirelessly Connected Forearm Prosthesis
by Octavian Narcis Ionescu, Eduard Franti, Vlad Carbunaru, Carmen Moldovan, Silviu Dinulescu, Marian Ion, David Catalin Dragomir, Carmen Marinela Mihailescu, Ioan Lascar, Ana Maria Oproiu, Tiberiu Paul Neagu, Ruxandra Costea, Monica Dascalu, Mihai Daniel Teleanu, Gabriela Ionescu and Raluca Teleanu
Biosensors 2024, 14(1), 31; https://doi.org/10.3390/bios14010031 - 9 Jan 2024
Viewed by 1384
Abstract
There is great interest in the development of prosthetic limbs capable of complex activities that are wirelessly connected to the patient’s neural system. Although some progress has been achieved in this area, one of the main problems encountered is the selective acquisition of [...] Read more.
There is great interest in the development of prosthetic limbs capable of complex activities that are wirelessly connected to the patient’s neural system. Although some progress has been achieved in this area, one of the main problems encountered is the selective acquisition of nerve impulses and the closing of the automation loop through the selective stimulation of the sensitive branches of the patient. Large-scale research and development have achieved so-called “cuff electrodes”; however, they present a big disadvantage: they are not selective. In this article, we present the progress made in the development of an implantable system of plug neural microelectrodes that relate to the biological nerve tissue and can be used for the selective acquisition of neuronal signals and for the stimulation of specific nerve fascicles. The developed plug electrodes are also advantageous due to their small thickness, as they do not trigger nerve inflammation. In addition, the results of the conducted tests on a sous scrofa subject are presented. Full article
(This article belongs to the Special Issue Recent Advances in Microneedle Array Electrodes in Biomedicine)
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10 pages, 3096 KiB  
Communication
The Quantitative Detection of Cystatin-C in Patient Samples Using a Colorimetric Lateral Flow Immunoassay
by Santosh Kumar Bikkarolla, Kavipriya Venkatesan, Yeddula Rebecca Revathy, Sowmya Parameswaran, Subramanian Krishnakumar and Dhananjaya Dendukuri
Biosensors 2024, 14(1), 30; https://doi.org/10.3390/bios14010030 - 8 Jan 2024
Cited by 1 | Viewed by 1651
Abstract
A colloidal gold-based lateral flow immunoassay was developed for the rapid quantitative detection of Cystatin-C in serum and whole blood. This device has an assay time of 15 min, making it a convenient point-of-care diagnostic tool. The device has a quantification range spanning [...] Read more.
A colloidal gold-based lateral flow immunoassay was developed for the rapid quantitative detection of Cystatin-C in serum and whole blood. This device has an assay time of 15 min, making it a convenient point-of-care diagnostic tool. The device has a quantification range spanning from 0.5 to 7.5 µg/mL, with a lower limit of detection at 0.18 µg/mL. To validate its accuracy, the test was compared to a standard nephelometric immunoassay, and the results exhibited a robust linear correlation with an adjusted r2 value of 0.95. Furthermore, the device demonstrates satisfactory levels of analytical performance in terms of precision, sensitivity, and interference, indicating its potential for precise Cystatin-C quantification, particularly in renal-failure patients. Notably, the Cystatin-C-LFA device also demonstrates satisfactory stability, as a 30-day accelerated stability study at 50 °C showed no change in the device performance, indicating a long shelf life for the product when stored at room temperature. Full article
(This article belongs to the Special Issue Biochips and Biosensors for Health-Care and Diagnostics)
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20 pages, 2892 KiB  
Review
Microfluidic-Based Non-Invasive Wearable Biosensors for Real-Time Monitoring of Sweat Biomarkers
by Seyedeh Rojin Shariati Pour, Donato Calabria, Afsaneh Emamiamin, Elisa Lazzarini, Andrea Pace, Massimo Guardigli, Martina Zangheri and Mara Mirasoli
Biosensors 2024, 14(1), 29; https://doi.org/10.3390/bios14010029 - 4 Jan 2024
Cited by 1 | Viewed by 2520
Abstract
Wearable biosensors are attracting great interest thanks to their high potential for providing clinical-diagnostic information in real time, exploiting non-invasive sampling of biofluids. In this context, sweat has been demonstrated to contain physiologically relevant biomarkers, even if it has not been exhaustively exploited [...] Read more.
Wearable biosensors are attracting great interest thanks to their high potential for providing clinical-diagnostic information in real time, exploiting non-invasive sampling of biofluids. In this context, sweat has been demonstrated to contain physiologically relevant biomarkers, even if it has not been exhaustively exploited till now. This biofluid has started to gain attention thanks to the applications offered by wearable biosensors, as it is easily collectable and can be used for continuous monitoring of some parameters. Several studies have reported electrochemical and optical biosensing strategies integrated with flexible, biocompatible, and innovative materials as platforms for biospecific recognition reactions. Furthermore, sampling systems as well as the transport of fluids by microfluidics have been implemented into portable and compact biosensors to improve the wearability of the overall analytical device. In this review, we report and discuss recent pioneering works about the development of sweat sensing technologies, focusing on opportunities and open issues that can be decisive for their applications in routine-personalized healthcare practices. Full article
(This article belongs to the Special Issue Microfluidics and MEMS for Diagnostics and Biomedical Applications)
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14 pages, 4439 KiB  
Article
An Electrochemical Aptasensor for the Detection of Freshwater Cyanobacteria
by Mai-Lan Pham, Somayeh Maghsoomi and Martin Brandl
Biosensors 2024, 14(1), 28; https://doi.org/10.3390/bios14010028 - 4 Jan 2024
Viewed by 1417
Abstract
Aphanizomenon is a genus of cyanobacteria that is filamentous and nitrogen-fixing and inhabits aquatic environments. This genus is known as one of the major producers of cyanotoxins that can affect water quality after the bloom period. In this study, an electrochemical aptasensor is [...] Read more.
Aphanizomenon is a genus of cyanobacteria that is filamentous and nitrogen-fixing and inhabits aquatic environments. This genus is known as one of the major producers of cyanotoxins that can affect water quality after the bloom period. In this study, an electrochemical aptasensor is demonstrated using a specific aptamer to detect Aphanizomenon sp. ULC602 for the rapid and sensitive detection of this bacterium. The principal operation of the generated aptasensor is based on the conformational change in the aptamer attached to the electrode surface in the presence of the target bacterium, resulting in a decrease in the current peak, which is measured by square-wave voltammetry (SWV). This aptasensor has a limit of detection (LOD) of OD750~0.3, with an extension to OD750~1.2 and a sensitivity of 456.8 μA·OD750−1·cm−2 without interference from other cyanobacteria. This is the first aptasensor studied that provides rapid detection to monitor the spread of this bacterium quickly in a targeted manner. Full article
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