Next Issue
Volume 11, November
Previous Issue
Volume 11, September
 
 
Search for Articles:
Title / Keyword
Author / Affiliation / Email
Journal
Article Type
 
 
Advanced Search
 
Section
Special Issue
Volume
Issue
Number
Page
 
6.6
4.9
Journals
Biosensors
Volume 11
Issue 10
share announcement

Biosensors, Volume 11, Issue 10 (October 2021) – 57 articles

Cover Story (view full-size image): Using a simple approach combining virus enrichment and naked eye detection techniques, this study investigated the impacts of rapid molecular diagnosis of SARS-CoV2 in clinical samples from COVID-19 patients. The self-powered sample preparation assay for virus enrichment and RNA extraction and the reverse transcription (RT)-LAMP-based lateral flow assay for naked-eye detection of SARS-CoV2 can be operated by hand. Results show that the COVID‐19 molecular diagnostics system not only allows for pathogen enrichment but also for the simple and rapid detection of pathogens within 60 min. It is hoped that the system provides a simple, sensitive, facile, efficient, and inexpensive strategy that can easily be applied for the diagnosis of emerging infectious diseases, such as COVID‐19, as a self-testing in future pandemic.View this paper
  • Issues are regarded as officially published after their release is announced to the table of contents alert mailing list.
  • You may sign up for e-mail alerts to receive table of contents of newly released issues.
  • PDF is the official format for papers published in both, html and pdf forms. To view the papers in pdf format, click on the "PDF Full-text" link, and use the free Adobe Reader to open them.
Order results
Result details
Section
Show export options expand_more Show export options expand_less
Select all
Export citation of selected articles as:
26 pages, 3518 KiB  
Review
A Review of Capillary Pressure Control Valves in Microfluidics
by Shaoxi Wang, Xiafeng Zhang, Cong Ma, Sheng Yan, David Inglis and Shilun Feng
Biosensors 2021, 11(10), 405; https://doi.org/10.3390/bios11100405 - 19 Oct 2021
Cited by 25 | Viewed by 11764
Abstract
Microfluidics offer microenvironments for reagent delivery, handling, mixing, reaction, and detection, but often demand the affiliated equipment for liquid control for these functions. As a helpful tool, the capillary pressure control valve (CPCV) has become popular to avoid using affiliated equipment. Liquid can [...] Read more.
Microfluidics offer microenvironments for reagent delivery, handling, mixing, reaction, and detection, but often demand the affiliated equipment for liquid control for these functions. As a helpful tool, the capillary pressure control valve (CPCV) has become popular to avoid using affiliated equipment. Liquid can be handled in a controlled manner by using the bubble pressure effects. In this paper, we analyze and categorize the CPCVs via three determining parameters: surface tension, contact angle, and microchannel shape. Finally, a few application scenarios and impacts of CPCV are listed, which includes how CPVC simplify automation of microfluidic networks, work with other driving modes; make extensive use of microfluidics by open channel, and sampling and delivery with controlled manners. The authors hope this review will help the development and use of the CPCV in microfluidic fields in both research and industry. Full article
(This article belongs to the Special Issue Microfluidics for Biosensing)
►▼ Show Figures

Figure 1

12 pages, 530 KiB  
Article
Chronic Study on Brainwave Authentication in a Real-Life Setting: An LSTM-Based Bagging Approach
by Liuyin Yang, Arno Libert and Marc M. Van Hulle
Biosensors 2021, 11(10), 404; https://doi.org/10.3390/bios11100404 - 18 Oct 2021
Cited by 4 | Viewed by 2886
Abstract
With the advent of the digital age, concern about how to secure authorized access to sensitive data is increasing. Besides traditional authentication methods, there is an interest in biometric traits such as fingerprints, the iris, facial characteristics, and, recently, brainwaves, primarily based on [...] Read more.
With the advent of the digital age, concern about how to secure authorized access to sensitive data is increasing. Besides traditional authentication methods, there is an interest in biometric traits such as fingerprints, the iris, facial characteristics, and, recently, brainwaves, primarily based on electroencephalography (EEG). Current work on EEG-based authentication focuses on acute recordings in laboratory settings using high-end equipment, typically equipped with 64 channels and operating at a high sampling rate. In this work, we validated the feasibility of EEG-based authentication in a real-world, out-of-laboratory setting using a commercial dry-electrode EEG headset and chronic recordings on a population of 15 healthy people. We used an LSTM-based network with bootstrap aggregating (bagging) to decode our recordings in response to a multitask scheme consisting of performed and imagined motor tasks, and showed that it improved the performance of the standard LSTM approach. We achieved an authentication accuracy, false acceptance rate (FAR), and false rejection rate (FRR) of 92.6%, 2.5%, and 5.0% for the performed motor task; 92.5%, 2.6%, and 4.9% for the imagined motor task; and 93.0%, 1.9%, and 5.1% for the combined tasks, respectively. We recommend the proposed method for time- and data-limited scenarios. Full article
(This article belongs to the Section Intelligent Biosensors and Bio-Signal Processing)
►▼ Show Figures

Figure 1

11 pages, 3846 KiB  
Communication
Biometric Identification of Taxodium spp. and Their Hybrid Progenies by Electrochemical Fingerprints
by Yuhong Zheng, Da Wang, Xiaolong Li, Ziyang Wang, Qingwei Zhou, Li Fu, Yunlong Yin and David Creech
Biosensors 2021, 11(10), 403; https://doi.org/10.3390/bios11100403 - 18 Oct 2021
Cited by 44 | Viewed by 2273
Abstract
The use of electrochemical fingerprints for plant identification is an emerging application in biosensors. In this work, Taxodium ascendens, T. distichum, T. mucronatum, and 18 of their hybrid progenies were collected for this purpose. This is the first attempt to [...] Read more.
The use of electrochemical fingerprints for plant identification is an emerging application in biosensors. In this work, Taxodium ascendens, T. distichum, T. mucronatum, and 18 of their hybrid progenies were collected for this purpose. This is the first attempt to use electrochemical fingerprinting for the identification of plant hybrid progeny. Electrochemical fingerprinting in the leaves of Taxodium spp. was recorded under two conditions. The results showed that the electrochemical fingerprints of each species and progeny possessed very suitable reproducibility. These electrochemical fingerprints represent the electrochemical behavior of electrochemically active substances in leaf tissues under specific conditions. Since these species and progenies are very closely related to each other, it is challenging to identify them directly using a particular electrochemical fingerprinting. Therefore, electrochemical fingerprints measured under different conditions were used to perform pattern recognition. We can identify different species and progenies by locating the features in different pattern maps. We also performed a phylogenetic study with data from electrochemical fingerprinting. The results proved that the electrochemical classification results and the relationship between them are closely related. Full article
(This article belongs to the Special Issue Electrochemical Sensors for Biometrics)
►▼ Show Figures

Figure 1

17 pages, 1735 KiB  
Article
Enhanced Plasmonic Biosensor Utilizing Paired Antibody and Label-Free Fe3O4 Nanoparticles for Highly Sensitive and Selective Detection of Parkinson’s α-Synuclein in Serum
by Samuel Husin Surya Mandala, Tai-Jan Liu, Chiung-Mei Chen, Kuo-Kang Liu, Mochamad Januar, Ying-Feng Chang, Chao-Sung Lai, Kuo-Hsuan Chang and Kou-Chen Liu
Biosensors 2021, 11(10), 402; https://doi.org/10.3390/bios11100402 - 18 Oct 2021
Cited by 14 | Viewed by 4157
Abstract
Parkinson’s disease (PD) is an acute and progressive neurodegenerative disorder, and diagnosis of the disease at its earliest stage is of paramount importance to improve the life expectancy of patients. α-Synuclein (α-syn) is a potential biomarker for the early diagnosis [...] Read more.
Parkinson’s disease (PD) is an acute and progressive neurodegenerative disorder, and diagnosis of the disease at its earliest stage is of paramount importance to improve the life expectancy of patients. α-Synuclein (α-syn) is a potential biomarker for the early diagnosis of PD, and there is a great need to develop a biosensing platform that precisely detects α-syn in human body fluids. Herein, we developed a surface plasmon resonance (SPR) biosensor based on the label-free iron oxide nanoparticles (Fe3O4 NPs) and paired antibody for the highly sensitive and selective detection of α-syn in serum samples. The sensitivity of the SPR platform is enhanced significantly by directly depositing Fe3O4 NPs on the Au surface at a high density to increase the decay length of the evanescent field on the Au film. Moreover, the utilization of rabbit-type monoclonal antibody (α-syn-RmAb) immobilized on Au films allows the SPR platform to have a high affinity-selectivity binding performance compared to mouse-type monoclonal antibodies as a common bioreceptor for capturing α-syn molecules. As a result, the current platform has a detection limit of 5.6 fg/mL, which is 20,000-fold lower than that of commercial ELISA. The improved sensor chip can also be easily regenerated to repeat the α-syn measurement with the same sensitivity. Furthermore, the SPR sensor was applied to the direct analysis of α-syn in serum samples. By using a format of paired α-syn-RmAb, the SPR sensor provides a recovery rate in the range from 94.5% to 104.3% to detect the α-syn in diluted serum samples precisely. This work demonstrates a highly sensitive and selective quantification approach to detect α-syn in human biofluids and paves the way for the future development in the early diagnosis of PD. Full article
(This article belongs to the Section Optical and Photonic Biosensors)
►▼ Show Figures

Figure 1

12 pages, 1660 KiB  
Article
Dielectrophoretic and Electrical Impedance Differentiation of Cancerous Cells Based on Biophysical Phenotype
by Ina Turcan, Iuliana Caras, Thomas Gabriel Schreiner, Catalin Tucureanu, Aurora Salageanu, Valentin Vasile, Marioara Avram, Bianca Tincu and Marius Andrei Olariu
Biosensors 2021, 11(10), 401; https://doi.org/10.3390/bios11100401 - 17 Oct 2021
Cited by 13 | Viewed by 3031
Abstract
Here, we reported a study on the detection and electrical characterization of both cancer cell line and primary tumor cells. Dielectrophoresis (DEP) and electrical impedance spectroscopy (EIS) were jointly employed to enable the rapid and label-free differentiation of various cancer cells from normal [...] Read more.
Here, we reported a study on the detection and electrical characterization of both cancer cell line and primary tumor cells. Dielectrophoresis (DEP) and electrical impedance spectroscopy (EIS) were jointly employed to enable the rapid and label-free differentiation of various cancer cells from normal ones. The primary tumor cells that were collected from two colorectal cancer patients, cancer cell lines (SW-403, Jurkat, and THP-1), and healthy peripheral blood mononuclear cells (PBMCs) were trapped first at the level of interdigitated microelectrodes with the help of dielectrophoresis. Correlation of the cells dielectric characteristics that was obtained via electrical impedance spectroscopy (EIS) allowed evident differentiation of the various types of cell. The differentiations were assigned to a “dielectric phenotype” based on their crossover frequencies. Finally, Randles equivalent circuit model was employed for highlighting the differences with regard to a series group of charge transport resistance and constant phase element for cancerous and normal cells. Full article
(This article belongs to the Special Issue Electrical and Electro-Optical Biosensors)
►▼ Show Figures

Figure 1

8 pages, 2259 KiB  
Communication
Self-Referenced Refractive Index Biosensing with Graphene Fano Resonance Modes
by Xiaoyu Dai, Banxian Ruan and Yuanjiang Xiang
Biosensors 2021, 11(10), 400; https://doi.org/10.3390/bios11100400 - 17 Oct 2021
Cited by 8 | Viewed by 5144
Abstract
A hybrid structure composed of periodic monolayer graphene nanoribbons and a dielectric multilayer structure was designed to generate a Fano resonance (FR). The strong interaction between the surface plasmon resonance of graphene and the dielectric waveguide mode results in the FR. The finite [...] Read more.
A hybrid structure composed of periodic monolayer graphene nanoribbons and a dielectric multilayer structure was designed to generate a Fano resonance (FR). The strong interaction between the surface plasmon resonance of graphene and the dielectric waveguide mode results in the FR. The finite element method is utilized to investigate the behaviors of the FR, and it matches well with the theoretical calculations using rigorous coupled wave theory. The results demonstrate that the profile of the FR can be passively tuned by the period of the graphene nanoribbons and actively tuned by the Fermi level of the graphene. The decoupled nature of the FR gives it potential applications as a self-calibrated refractive index biosensor, and the sensitivity can reach as high as 4.615 μm/RIU. Thus, this work provides a new idea for an excellent self-referencing refractive index biosensor. Full article
(This article belongs to the Special Issue Optical Biosensor with 2D Materials and Metamaterials)
►▼ Show Figures

Figure 1

11 pages, 2554 KiB  
Article
Investigating the Regulation of Neural Differentiation and Injury in PC12 Cells Using Microstructure Topographic Cues
by Xindi Sun, Wei Li, Xiuqing Gong, Guohui Hu, Junyi Ge, Jinbo Wu and Xinghua Gao
Biosensors 2021, 11(10), 399; https://doi.org/10.3390/bios11100399 - 16 Oct 2021
Cited by 5 | Viewed by 2981
Abstract
In this study, we designed and manufactured a series of different microstructure topographical cues for inducing neuronal differentiation of cells in vitro, with different topography, sizes, and structural complexities. We cultured PC12 cells in these microstructure cues and then induced neural differentiation using [...] Read more.
In this study, we designed and manufactured a series of different microstructure topographical cues for inducing neuronal differentiation of cells in vitro, with different topography, sizes, and structural complexities. We cultured PC12 cells in these microstructure cues and then induced neural differentiation using nerve growth factor (NGF). The pheochromocytoma cell line PC12 is a validated neuronal cell model that is widely used to study neuronal differentiation. Relevant markers of neural differentiation and cytoskeletal F-actin were characterized. Cellular immunofluorescence detection and axon length analysis showed that the differentiation of PC12 cells was significantly different under different isotropic and anisotropic topographic cues. The expression differences of the growth cone marker growth-associated protein 43 (GAP-43) and sympathetic nerve marker tyrosine hydroxylase (TH) genes were also studied in different topographic cues. Our results revealed that the physical environment has an important influence on the differentiation of neuronal cells, and 3D constraints could be used to guide axon extension. In addition, the neurotoxin 6-hydroxydopamine (6-OHDA) was used to detect the differentiation and injury of PC12 cells under different topographic cues. Finally, we discussed the feasibility of combining the topographic cues and the microfluidic chip for neural differentiation research. Full article
(This article belongs to the Special Issue Microfluidics for Biosensing)
►▼ Show Figures

Figure 1

22 pages, 5948 KiB  
Article
Electrical Impedance of Upper Limb Enables Robust Wearable Identity Recognition against Variation in Finger Placement and Environmental Factors
by Hyung Wook Noh, Joo Yong Sim, Chang-Geun Ahn and Yunseo Ku
Biosensors 2021, 11(10), 398; https://doi.org/10.3390/bios11100398 - 16 Oct 2021
Cited by 2 | Viewed by 2515
Abstract
Most biometric authentication technologies commercialized in various fields mainly rely on acquired images of structural information, such as fingerprints, irises, and faces. However, bio-recognition techniques using these existing physical features are always at risk of template forgery threats, such as fake fingerprints. Due [...] Read more.
Most biometric authentication technologies commercialized in various fields mainly rely on acquired images of structural information, such as fingerprints, irises, and faces. However, bio-recognition techniques using these existing physical features are always at risk of template forgery threats, such as fake fingerprints. Due to the risk of theft and duplication, studies have recently been attempted using the internal structure and biological characteristics of the human body, including our previous works on the ratiometric biological impedance feature. However, one may still question its accuracy in real-life use due to the artifacts from sensing position variability and electrode–skin interfacing noise. Moreover, since the finger possesses more severe thermoregulatory vasomotion and large variability in the tissue properties than the core of the body, it is necessary to mitigate the harsh changes occurring at the peripheral extremities of the human body. To address these challenges, we propose a biometric authentication method through robust feature extraction from the upper-limb impedance acquired based on a portable wearable device. In this work, we show that the upper limb impedance features obtained from wearable devices are robust against undesirable factors such as finger placement deviations and day-to-day physiological changes, along with ratiometric impedance features. Overall, our upper-limb impedance-based analysis in a dataset of 1627 measurement from 33 subjects lowered the classification error rate from 22.38% to 4.3% (by a factor of 5), and further down to 2.4% (by a factor of 9) when combined with the ratiometric features. Full article
(This article belongs to the Section Biosensor and Bioelectronic Devices)
►▼ Show Figures

Figure 1

10 pages, 4135 KiB  
Article
Computer Simulation of a Surface Charge Nanobiosensor with Internal Signal Integration
by Dmitry Dyubo and Oleg Yu. Tsybin
Biosensors 2021, 11(10), 397; https://doi.org/10.3390/bios11100397 - 16 Oct 2021
Cited by 5 | Viewed by 2160
Abstract
The ionized states of molecular analytes located on solid surfaces require profound investigation and better understanding for applications in the basic sciences in general, and in the design of nanobiosensors, in particular. Such ionized states are induced by the interactions of molecules between [...] Read more.
The ionized states of molecular analytes located on solid surfaces require profound investigation and better understanding for applications in the basic sciences in general, and in the design of nanobiosensors, in particular. Such ionized states are induced by the interactions of molecules between them in the analyzed substance and with the target surface. Here, computer simulations using COMSOL Multiphysics software show the effect of surface charge density and distribution on the output generation in a dynamic PIN diode with gate control. This device, having built-in potential barriers, has a unique internal integration of output signal generation. The identified interactions showed the possibility of a new design for implementing a nanobiosensor based on a dynamic PIN diode in a mode with surface charge control. Full article
(This article belongs to the Section Intelligent Biosensors and Bio-Signal Processing)
►▼ Show Figures

Figure 1

27 pages, 3981 KiB  
Review
Malignancies and Biosensors: A Focus on Oral Cancer Detection through Salivary Biomarkers
by Riccardo Goldoni, Alessandra Scolaro, Elisa Boccalari, Carolina Dolci, Antonio Scarano, Francesco Inchingolo, Paolo Ravazzani, Paola Muti and Gianluca Tartaglia
Biosensors 2021, 11(10), 396; https://doi.org/10.3390/bios11100396 - 15 Oct 2021
Cited by 47 | Viewed by 8379
Abstract
Oral cancer is among the deadliest types of malignancy due to the late stage at which it is usually diagnosed, leaving the patient with an average five-year survival rate of less than 50%. The booming field of biosensing and point of care diagnostics [...] Read more.
Oral cancer is among the deadliest types of malignancy due to the late stage at which it is usually diagnosed, leaving the patient with an average five-year survival rate of less than 50%. The booming field of biosensing and point of care diagnostics can, in this regard, play a major role in the early detection of oral cancer. Saliva is gaining interest as an alternative biofluid for non-invasive diagnostics, and many salivary biomarkers of oral cancer have been proposed. While these findings are promising for the application of salivaomics tools in routine practice, studies on larger cohorts are still needed for clinical validation. This review aims to summarize the most recent development in the field of biosensing related to the detection of salivary biomarkers commonly associated with oral cancer. An introduction to oral cancer diagnosis, prognosis and treatment is given to define the clinical problem clearly, then saliva as an alternative biofluid is presented, along with its advantages, disadvantages, and collection procedures. Finally, a brief paragraph on the most promising salivary biomarkers introduces the sensing technologies commonly exploited to detect oral cancer markers in saliva. Hence this review provides a comprehensive overview of both the clinical and technological advantages and challenges associated with oral cancer detection through salivary biomarkers. Full article
(This article belongs to the Section Biosensors and Healthcare)
►▼ Show Figures

Figure 1

14 pages, 11521 KiB  
Article
Topographical Vacuum Sealing of 3D-Printed Multiplanar Microfluidic Structures
by Benjamin Heidt, Renato Rogosic, Nils Leoné, Eduardo J. S. Brás, Thomas J. Cleij, Jules A. W. Harings, Hanne Diliën, Kasper Eersels and Bart van Grinsven
Biosensors 2021, 11(10), 395; https://doi.org/10.3390/bios11100395 - 15 Oct 2021
Cited by 7 | Viewed by 3099
Abstract
We demonstrate a novel way of creating three-dimensional microfluidic channels capable of following complex topographies. To this end, substrates with open channels and different geometries were 3D-printed, and the open channels were consecutively closed with a thermoplastic using a low-resolution vacuum-forming approach. This [...] Read more.
We demonstrate a novel way of creating three-dimensional microfluidic channels capable of following complex topographies. To this end, substrates with open channels and different geometries were 3D-printed, and the open channels were consecutively closed with a thermoplastic using a low-resolution vacuum-forming approach. This process allows the sealing of channels that are located on the surface of complex multiplanar topographies, as the thermoplastic aligns with the surface-shape (the macrostructure) of the substrate, while the microchannels remain mostly free of thermoplastic as their small channel size resists thermoplastic inflow. This new process was analyzed for its capability to consistently close different substrate geometries, which showed reliable sealing of angles >90°. Furthermore, the thermoplastic intrusion into channels of different widths was quantified, showing a linear effect of channel width and percentage of thermoplastic intrusion; ranging from 43.76% for large channels with 2 mm width to only 5.33% for channels with 500 µm channel width. The challenging sealing of substrate ‘valleys’, which are created when two large protrusions are adjacent to each other, was investigated and the correlation between protrusion distance and height is shown. Lastly, we present three application examples: a serpentine mixer with channels spun around a cuboid, increasing the usable surface area; a cuvette-inspired flow cell for a 2-MXP biosensor based on molecular imprinted polymers, fitting inside a standard UV/Vis-Spectrophotometer; and an adapter system that can be manufactured by one-sided injection molding and is self-sealed before usage. These examples demonstrate how this novel technology can be used to easily adapt microfluidic circuits for application in biosensor platforms. Full article
(This article belongs to the Special Issue 3D Biosensor and Microfluidic Devices for Developing Next Generation Point of Care Diagnostic Devices of Biomonitoring)
►▼ Show Figures

Figure 1

24 pages, 1423 KiB  
Review
Liquid Biopsy-Based Biosensors for MRD Detection and Treatment Monitoring in Non-Small Cell Lung Cancer (NSCLC)
by Parvaneh Sardarabadi, Amir Asri Kojabad, Davod Jafari and Cheng-Hsien Liu
Biosensors 2021, 11(10), 394; https://doi.org/10.3390/bios11100394 - 15 Oct 2021
Cited by 17 | Viewed by 6382
Abstract
Globally, non-small cell lung cancer (NSCLC) is the leading cause of cancer deaths. Despite advancements in chemotherapy and targeted therapies, the 5-year survival rate has remained at 16% for the past forty years. Minimal residual disease (MRD) is described as the existence of [...] Read more.
Globally, non-small cell lung cancer (NSCLC) is the leading cause of cancer deaths. Despite advancements in chemotherapy and targeted therapies, the 5-year survival rate has remained at 16% for the past forty years. Minimal residual disease (MRD) is described as the existence of either isolated tumour cells or circulating tumour cells in biological liquid of patients after removal of the primary tumour without any clinical signs of cancer. Recently, liquid biopsy has been promising as a non-invasive method of disease monitoring and treatment guidelines as an MRD marker. Liquid biopsy could be used to detect and assess earlier stages of NSCLC, post-treatment MRD, resistance to targeted therapies, immune checkpoint inhibitors (ICIs) and tumour mutational burden. MRD surveillance has been proposed as a potential marker for lung cancer relapse. Principally, biosensors provide the quantitative analysis of various materials by converting biological functions into quantifiable signals. Biosensors are usually operated to detect antibodies, enzymes, DNA, RNA, extracellular vesicles (EVs) and whole cells. Here, we present a category of biosensors based on the signal transduction method for identifying biosensor-based biomarkers in liquid biopsy specimens to monitor lung cancer treatment. Full article
(This article belongs to the Special Issue Immunosensors - Trends and Perspective)
►▼ Show Figures

Figure 1

15 pages, 5401 KiB  
Article
Biomechanical and Physiological Evaluation of a Multi-Joint Exoskeleton with Active-Passive Assistance for Walking
by Wujing Cao, Zhewen Zhang, Chunjie Chen, Yong He, Dashuai Wang and Xinyu Wu
Biosensors 2021, 11(10), 393; https://doi.org/10.3390/bios11100393 - 15 Oct 2021
Cited by 5 | Viewed by 3488
Abstract
How to improve the walking efficiency while ensuring the wearability is an important issue of lower limb exoskeletons. Active devices can provide greater forces, while the passive devices have advantage in weight. We presented a multi-joint exoskeleton with active hip extension assistance and [...] Read more.
How to improve the walking efficiency while ensuring the wearability is an important issue of lower limb exoskeletons. Active devices can provide greater forces, while the passive devices have advantage in weight. We presented a multi-joint exoskeleton with active hip extension assistance and passive ankle plantarflexion assistance in this work. An admittance controller based on a feedforward model was proposed to track the desired active force of the hip extension. An underfoot clutch mechanism was adapted to realize the passive ankle plantarflexion assistance. To assess the efficacy of the multi-joint exoskeleton in assisting walking, we conducted comprehensive experiments to evaluate the force tracking performance, lower limb muscle activities and metabolic cost. The results demonstrated that: (i) The average tracking error of the peak hip extension assistance force from three subjects was less than 3%. (ii) The reductions of normalized root-mean-square EMG in the lateral soleus, medial soleus and gluteus maximus of eight subjects achieved 15.33%, 11.11%, and 3.74%, respectively. (iii) The average metabolic cost of six subjects was reduced by 10.41% under exoskeleton on (EO) condition comparing to the condition of walking with no exoskeleton (NE). This work proved that the concept of the multi-joint exoskeleton with active-passive assistance can improve the walking efficiency. Full article
(This article belongs to the Special Issue Biosensors in Rehabilitation and Assistance Robotics)
►▼ Show Figures

Figure 1

13 pages, 1726 KiB  
Article
On-Site Detection of Carcinoembryonic Antigen in Human Serum
by Tohid Mahmoudi, Mohammad Pourhassan-Moghaddam, Behnaz Shirdel, Behzad Baradaran, Eden Morales-Narváez and Hamed Golmohammadi
Biosensors 2021, 11(10), 392; https://doi.org/10.3390/bios11100392 - 14 Oct 2021
Cited by 16 | Viewed by 3527
Abstract
Real-time connectivity and employment of sustainable materials empowers point-of-care diagnostics with the capability to send clinically relevant data to health care providers even in low-resource settings. In this study, we developed an advantageous kit for the on-site detection of carcinoembryonic antigen (CEA) in [...] Read more.
Real-time connectivity and employment of sustainable materials empowers point-of-care diagnostics with the capability to send clinically relevant data to health care providers even in low-resource settings. In this study, we developed an advantageous kit for the on-site detection of carcinoembryonic antigen (CEA) in human serum. CEA sensing was performed using cellulose-based lateral flow strips, and colorimetric signals were read, processed, and measured using a smartphone-based system. The corresponding immunoreaction was reported by polydopamine-modified gold nanoparticles in order to boost the signal intensity and improve the surface blocking and signal-to-noise relationship, thereby enhancing detection sensitivity when compared with bare gold nanoparticles (up to 20-fold in terms of visual limit of detection). Such lateral flow strips showed a linear range from 0.05 to 50 ng/mL, with a visual limit of detection of 0.05 ng/mL and an assay time of 15 min. Twenty-six clinical samples were also tested using the proposed kit and compared with the gold standard of immunoassays (enzyme linked immunosorbent assay), demonstrating an excellent correlation (R = 0.99). This approach can potentially be utilized for the monitoring of cancer treatment, particularly at locations far from centralized laboratory facilities. Full article
(This article belongs to the Special Issue Cellulose-Based Biosensing Platforms)
►▼ Show Figures

Figure 1

19 pages, 1982 KiB  
Article
Oxygen Saturation Behavior by Pulse Oximetry in Female Athletes: Breaking Myths
by Pilar Martín-Escudero, Ana María Cabanas, Manuel Fuentes-Ferrer and Mercedes Galindo-Canales
Biosensors 2021, 11(10), 391; https://doi.org/10.3390/bios11100391 - 14 Oct 2021
Cited by 14 | Viewed by 4665
Abstract
The myths surrounding women’s participation in sport have been reflected in respiratory physiology. This study aims to demonstrate that continuous monitoring of blood oxygen saturation during a maximal exercise test in female athletes is highly correlated with the determination of the second ventilatory [...] Read more.
The myths surrounding women’s participation in sport have been reflected in respiratory physiology. This study aims to demonstrate that continuous monitoring of blood oxygen saturation during a maximal exercise test in female athletes is highly correlated with the determination of the second ventilatory threshold (VT2) or anaerobic threshold (AnT). The measurements were performed using a pulse oximeter during a maximum effort test on a treadmill on a population of 27 healthy female athletes. A common behavior of the oxygen saturation evolution during the incremental exercise test characterized by a decrease in saturation before the aerobic threshold (AeT) followed by a second significant drop was observed. Decreases in peripheral oxygen saturation during physical exertion have been related to the athlete’s physical fitness condition. However, this drop should not be a limiting factor in women’s physical performance. We found statistically significant correlations between the maximum oxygen uptake and the appearance of the ventilatory thresholds (VT1 and VT2), the desaturation time, the total test time, and between the desaturation time and the VT2. We observed a relationship between the desaturation time and the VT2 appearance. Indeed, a linear regression model between the desaturation time and the VT2 appearance can predict 80% of the values in our sample. Besides, we suggest that pulse oximetry is a simple, fairly accurate, and non-invasive technique for studying the physical condition of athletes who perform physical exertion. Full article
(This article belongs to the Section Biosensors and Healthcare)
►▼ Show Figures

Figure 1

11 pages, 1815 KiB  
Article
Theoretical Model for a Highly Sensitive Near Infrared Biosensor Based on Bloch Surface Wave with Dirac Semimetal
by Qiwen Zheng, Yamei Liu, Wenguang Lu, Xiaoyu Dai, Haishan Tian and Leyong Jiang
Biosensors 2021, 11(10), 390; https://doi.org/10.3390/bios11100390 - 14 Oct 2021
Cited by 5 | Viewed by 2510
Abstract
In this work, we present a theoretical model of a near-infrared sensitive refractive index biosensor based on the truncate 1D photonic crystal (1D PC) structure with Dirac semimetal. This highly sensitive near-infrared biosensor originates from the sharp reflectance peak caused by the excitation [...] Read more.
In this work, we present a theoretical model of a near-infrared sensitive refractive index biosensor based on the truncate 1D photonic crystal (1D PC) structure with Dirac semimetal. This highly sensitive near-infrared biosensor originates from the sharp reflectance peak caused by the excitation of Bloch surface wave (BSW) at the interface between the Dirac semimetal and 1D PC. The sensitivity of the biosensor model is sensitive to the Fermi energy of Dirac semimetal, the thickness of the truncate layer and the refractive index of the sensing medium. By optimizing the structural parameters, the maximum refractive index sensitivity of the biosensor model can surpass 17.4 × 103/RIU, which achieves a certain competitiveness compared to conventional surface plasmon resonance (SPR) or BSW sensors. Considering that bulk materials are easier to handle than two-dimensional materials in manufacturing facilities, we judge that 3D Dirac semimetal and its related devices will provide a strong competitor and alternative to graphene-based devices. Full article
(This article belongs to the Special Issue Optical Biosensor with 2D Materials and Metamaterials)
►▼ Show Figures

Figure 1

20 pages, 2034 KiB  
Review
Brain–Computer Interfacing Using Functional Near-Infrared Spectroscopy (fNIRS)
by Kogulan Paulmurugan, Vimalan Vijayaragavan, Sayantan Ghosh, Parasuraman Padmanabhan and Balázs Gulyás
Biosensors 2021, 11(10), 389; https://doi.org/10.3390/bios11100389 - 13 Oct 2021
Cited by 27 | Viewed by 7652
Abstract
Functional Near-Infrared Spectroscopy (fNIRS) is a wearable optical spectroscopy system originally developed for continuous and non-invasive monitoring of brain function by measuring blood oxygen concentration. Recent advancements in brain–computer interfacing allow us to control the neuron function of the brain by combining it [...] Read more.
Functional Near-Infrared Spectroscopy (fNIRS) is a wearable optical spectroscopy system originally developed for continuous and non-invasive monitoring of brain function by measuring blood oxygen concentration. Recent advancements in brain–computer interfacing allow us to control the neuron function of the brain by combining it with fNIRS to regulate cognitive function. In this review manuscript, we provide information regarding current advancement in fNIRS and how it provides advantages in developing brain–computer interfacing to enable neuron function. We also briefly discuss about how we can use this technology for further applications. Full article
(This article belongs to the Special Issue Near Infrared (NIR) Biosensors and Imaging Techniques)
►▼ Show Figures

Figure 1

18 pages, 5331 KiB  
Article
Microfluidic Lab-on-a-Chip Based on UHF-Dielectrophoresis for Stemness Phenotype Characterization and Discrimination among Glioblastoma Cells
by Elisa Lambert, Rémi Manczak, Elodie Barthout, Sofiane Saada, Elena Porcù, Francesca Maule, Barbara Bessette, Giampietro Viola, Luca Persano, Claire Dalmay, Fabrice Lalloué and Arnaud Pothier
Biosensors 2021, 11(10), 388; https://doi.org/10.3390/bios11100388 - 13 Oct 2021
Cited by 15 | Viewed by 2831
Abstract
Glioblastoma (GBM) is one of the most aggressive solid tumors, particularly due to the presence of cancer stem cells (CSCs). Nowadays, the characterization of this cell type with an efficient, fast and low-cost method remains an issue. Hence, we have developed a microfluidic [...] Read more.
Glioblastoma (GBM) is one of the most aggressive solid tumors, particularly due to the presence of cancer stem cells (CSCs). Nowadays, the characterization of this cell type with an efficient, fast and low-cost method remains an issue. Hence, we have developed a microfluidic lab-on-a-chip based on dielectrophoresis (DEP) single cell electro-manipulation to measure the two crossover frequencies: fx01 in the low-frequency range (below 500 kHz) and fx02 in the ultra-high-frequency range (UHF, above 50 MHz). First, in vitro conditions were investigated. An U87-MG cell line was cultured in different conditions in order to induce an undifferentiated phenotype. Then, ex vivo GBM cells from patients’ primary cell culture were passed through the developed microfluidic system and characterized in order to reflect clinical conditions. This article demonstrates that the usual exploitation of low-frequency range DEP does not allow the discrimination of the undifferentiated GBM cells from the differentiated one. However, the presented study highlights the use of UHF-DEP as a relevant discriminant parameter. The proposed microfluidic lab-on-a-chip is able to follow the kinetics of U87-MG phenotype transformation in a CSC enrichment medium and the cancer stem cells phenotype acquirement. Full article
(This article belongs to the Special Issue Microfluidics for Biosensing)
►▼ Show Figures

Figure 1

11 pages, 1970 KiB  
Article
Noncontact Optical Measurement of Aqueous Humor Glucose Levels and Correlation with Serum Glucose Levels in Rabbit
by Yih-Shiou Hwang, Eugene Yu-Chuan Kang, Chia-Rui Shen, Wei-Hsin Hong and Wei-Chi Wu
Biosensors 2021, 11(10), 387; https://doi.org/10.3390/bios11100387 - 13 Oct 2021
Cited by 3 | Viewed by 2811
Abstract
The noninvasive measurement of serum glucose levels has been investigated for the monitoring of blood sugar control in diabetes. In our study, we aimed to develop a novel noncontact glucometer (NCGM) utilizing an optical approach to measure the intraocular aqueous humor glucose levels [...] Read more.
The noninvasive measurement of serum glucose levels has been investigated for the monitoring of blood sugar control in diabetes. In our study, we aimed to develop a novel noncontact glucometer (NCGM) utilizing an optical approach to measure the intraocular aqueous humor glucose levels in the anterior chamber of rabbit eyes. The NCGM consists of a hybrid optical system that simultaneously measures near-infrared absorption and the polarized rotatory distribution of glucose molecules in the aqueous humor. In vitro optical measurements demonstrated that NCGM measurements had high precision and repeatability for different glucose levels, including 50 mg/dL (14.36%), 100 mg/dL (−4.05%), 200 mg/dL (−5.99%), 300 mg/dL (4.86%), 400 mg/dL (−2.84%), 500 mg/dL (−0.11%), and 600 mg/dL (4.48%). In the rabbit experiments, we found a high correlation between aqueous glucose levels and serum glucose levels, with a mean difference of 8 mg/dL. According to the testing results, the in vivo NCGM measurement of aqueous humor glucose levels also displayed a high correlation with serum glucose levels, with a mean difference of 29.2 mg/dL. In conclusion, aqueous humor glucose levels were accurately measured using the NCGM, and the results correlated with serum glucose levels. Full article
(This article belongs to the Special Issue Glucose Sensors—an Essential Tool in Diabetes Management)
►▼ Show Figures

Figure 1

14 pages, 2132 KiB  
Article
Portable and Label-Free Quantitative Loop-Mediated Isothermal Amplification (LF-qLamp) for Reliable COVID-19 Diagnostics in Three Minutes of Reaction Time: Arduino-Based Detection System Assisted by a pH Microelectrode
by Mario Moisés Alvarez, Sergio Bravo-González, Everardo González-González and Grissel Trujillo-de Santiago
Biosensors 2021, 11(10), 386; https://doi.org/10.3390/bios11100386 - 13 Oct 2021
Cited by 8 | Viewed by 3707
Abstract
Loop-mediated isothermal amplification (LAMP) has been recently studied as an alternative method for cost-effective diagnostics in the context of the current COVID-19 pandemic. Recent reports document that LAMP-based diagnostic methods have a comparable sensitivity and specificity to that of RT-qPCR. We report the [...] Read more.
Loop-mediated isothermal amplification (LAMP) has been recently studied as an alternative method for cost-effective diagnostics in the context of the current COVID-19 pandemic. Recent reports document that LAMP-based diagnostic methods have a comparable sensitivity and specificity to that of RT-qPCR. We report the use of a portable Arduino-based LAMP-based amplification system assisted by pH microelectrodes for the accurate and reliable diagnosis of SARS-CoV-2 during the first 3 min of the amplification reaction. We show that this simple system enables a straightforward discrimination between samples containing or not containing artificial SARS-CoV-2 genetic material in the range of 10 to 10,000 copies per 50 µL of reaction mix. We also spiked saliva samples with SARS-CoV-2 synthetic material and corroborated that the LAMP reaction can be successfully monitored in real time using microelectrodes in saliva samples as well. These results may have profound implications for the design of real-time and portable quantitative systems for the reliable detection of viral pathogens including SARS-CoV-2. Full article
(This article belongs to the Special Issue Biosensors for Bacterial and Viral Detection)
►▼ Show Figures

Graphical abstract

18 pages, 3144 KiB  
Review
Applications of Microfluidics in Liquid Crystal-Based Biosensors
by Jinan Deng, Dandan Han and Jun Yang
Biosensors 2021, 11(10), 385; https://doi.org/10.3390/bios11100385 - 12 Oct 2021
Cited by 34 | Viewed by 3912
Abstract
Liquid crystals (LCs) with stimuli-responsive configuration transition and optical anisotropic properties have attracted enormous interest in the development of simple and label-free biosensors. The combination of microfluidics and the LCs offers great advantages over traditional LC-based biosensors including small sample consumption, fast analysis [...] Read more.
Liquid crystals (LCs) with stimuli-responsive configuration transition and optical anisotropic properties have attracted enormous interest in the development of simple and label-free biosensors. The combination of microfluidics and the LCs offers great advantages over traditional LC-based biosensors including small sample consumption, fast analysis and low cost. Moreover, microfluidic techniques provide a promising tool to fabricate uniform and reproducible LC-based sensing platforms. In this review, we emphasize the recent development of microfluidics in the fabrication and integration of LC-based biosensors, including LC planar sensing platforms and LC droplets. Fabrication and integration of LC-based planar platforms with microfluidics for biosensing applications are first introduced. The generation and entrapment of monodisperse LC droplets with different microfluidic structures, as well as their applications in the detection of chemical and biological species, are then summarized. Finally, the challenges and future perspectives of the development of LC-based microfluidic biosensors are proposed. This review will promote the understanding of microfluidic techniques in LC-based biosensors and facilitate the development of LC-based microfluidic biosensing devices with high performance. Full article
(This article belongs to the Special Issue Biosensors Based on Microfluidic Devices)
►▼ Show Figures

Figure 1

20 pages, 3010 KiB  
Review
Application of Functionalized Graphene Oxide Based Biosensors for Health Monitoring: Simple Graphene Derivatives to 3D Printed Platforms
by Agnivo Gosai, Kamil Reza Khondakar, Xiao Ma and Md. Azahar Ali
Biosensors 2021, 11(10), 384; https://doi.org/10.3390/bios11100384 - 10 Oct 2021
Cited by 44 | Viewed by 6002
Abstract
Biosensors hold great potential for revolutionizing personalized medicine and environmental monitoring. Their construction is the key factor which depends on either manufacturing techniques or robust sensing materials to improve efficacy of the device. Functional graphene is an attractive choice for transducing material due [...] Read more.
Biosensors hold great potential for revolutionizing personalized medicine and environmental monitoring. Their construction is the key factor which depends on either manufacturing techniques or robust sensing materials to improve efficacy of the device. Functional graphene is an attractive choice for transducing material due to its various advantages in interfacing with biorecognition elements. Graphene and its derivatives such as graphene oxide (GO) are thus being used extensively for biosensors for monitoring of diseases. In addition, graphene can be patterned to a variety of structures and is incorporated into biosensor devices such as microfluidic devices and electrochemical and plasmonic sensors. Among biosensing materials, GO is gaining much attention due to its easy synthesis process and patternable features, high functionality, and high electron transfer properties with a large surface area leading to sensitive point-of-use applications. Considering demand and recent challenges, this perspective review is an attempt to describe state-of-the-art biosensors based on functional graphene. Special emphasis is given to elucidating the mechanism of sensing while discussing different applications. Further, we describe the future prospects of functional GO-based biosensors for health care and environmental monitoring with a focus on additive manufacturing such as 3D printing. Full article
(This article belongs to the Special Issue 3D Biosensor and Microfluidic Devices for Developing Next Generation Point of Care Diagnostic Devices of Biomonitoring)
►▼ Show Figures

Figure 1

13 pages, 1985 KiB  
Article
Fibre-Optic Surface Plasmon Resonance Biosensor for Monoclonal Antibody Titer Quantification
by Thai Thao Ly, Yinlan Ruan, Bobo Du, Peipei Jia and Hu Zhang
Biosensors 2021, 11(10), 383; https://doi.org/10.3390/bios11100383 - 10 Oct 2021
Cited by 7 | Viewed by 3618
Abstract
An extraordinary optical transmission fibre-optic surface plasmon resonance biosensing platform was engineered to improve its portability and sensitivity, and was applied to monitor the concentrations of monoclonal antibodies (Mabs). By refining the fabricating procedure and changing the material of the flow cell and [...] Read more.
An extraordinary optical transmission fibre-optic surface plasmon resonance biosensing platform was engineered to improve its portability and sensitivity, and was applied to monitor the concentrations of monoclonal antibodies (Mabs). By refining the fabricating procedure and changing the material of the flow cell and the components of the optical fibre, the biosensor is portable and robust to external interference. After the implementation of an effective template cleaning procedure and precise control during the fabrication process, a consistent sensitivity of 509 ± 5 nm per refractive index unit (nm/RIU) was achieved. The biosensor can detect the Mab with a limit of detection (LOD) of 0.44 µg/mL. The results show that the biosensor is a potential tool for the rapid quantification of Mab titers. The biosensor can be regenerated at least 10 times with 10 mM glycine (pH = 2.5), and consistent signal changes were obtained after regeneration. Moreover, the employment of a spacer arm SM(PEG)2, used for immobilising protein A onto the gold film, was demonstrated to be unable to improve the detecting sensitivity; thus, a simple procedure without the spacer arm could be used to prepare the protein A-based biosensor. Our results demonstrate that the fibre-optic surface plasmon resonance biosensor is competent for the real-time and on-line monitoring of antibody titers in the future as a process analytical technologies (PATs) tool for bioprocess developments and the manufacture of therapeutic antibodies. Full article
(This article belongs to the Special Issue Bioprocess Monitoring, Measurement, and Control by Biosensor-Based Technologies)
►▼ Show Figures

Figure 1

21 pages, 2703 KiB  
Review
Nanozyme-Participated Biosensing of Pesticides and Cholinesterases: A Critical Review
by Hengjia Zhu, Peng Liu, Lizhang Xu, Xin Li, Panwang Hu, Bangxiang Liu, Jianming Pan, Fu Yang and Xiangheng Niu
Biosensors 2021, 11(10), 382; https://doi.org/10.3390/bios11100382 - 9 Oct 2021
Cited by 15 | Viewed by 4743
Abstract
To improve the output and quality of agricultural products, pesticides are globally utilized as an efficient tool to protect crops from insects. However, given that most pesticides used are difficult to decompose, they inevitably remain in agricultural products and are further enriched into [...] Read more.
To improve the output and quality of agricultural products, pesticides are globally utilized as an efficient tool to protect crops from insects. However, given that most pesticides used are difficult to decompose, they inevitably remain in agricultural products and are further enriched into food chains and ecosystems, posing great threats to human health and the environment. Thus, developing efficient methods and tools to monitor pesticide residues and related biomarkers (acetylcholinesterase and butylcholinesterase) became quite significant. With the advantages of excellent stability, tailorable catalytic performance, low cost, and easy mass production, nanomaterials with enzyme-like properties (nanozymes) are extensively utilized in fields ranging from biomedicine to environmental remediation. Especially, with the catalytic nature to offer amplified signals for highly sensitive detection, nanozymes were finding potential applications in the sensing of various analytes, including pesticides and their biomarkers. To highlight the progress in this field, here the sensing principles of pesticides and cholinesterases based on nanozyme catalysis are definitively summarized, and emerging detection methods and technologies with the participation of nanozymes are critically discussed. Importantly, typical examples are introduced to reveal the promising use of nanozymes. Also, some challenges in the field and future trends are proposed, with the hope of inspiring more efforts to advance nanozyme-involved sensors for pesticides and cholinesterases. Full article
(This article belongs to the Special Issue Biosensors in Food Analysis and Environmental Detection)
►▼ Show Figures

Figure 1

13 pages, 2926 KiB  
Article
Smartphone-Based Chemiluminescent Origami µPAD for the Rapid Assessment of Glucose Blood Levels
by Donato Calabria, Martina Zangheri, Ilaria Trozzi, Elisa Lazzarini, Andrea Pace, Mara Mirasoli and Massimo Guardigli
Biosensors 2021, 11(10), 381; https://doi.org/10.3390/bios11100381 - 9 Oct 2021
Cited by 23 | Viewed by 3387
Abstract
Microfluidic paper analytical devices (µPADs) represent one of the most appealing trends in the development of simple and inexpensive analytical systems for diagnostic applications at the point of care (POC). Herein, we describe a smartphone-based origami µPAD for the quantitative determination of glucose [...] Read more.
Microfluidic paper analytical devices (µPADs) represent one of the most appealing trends in the development of simple and inexpensive analytical systems for diagnostic applications at the point of care (POC). Herein, we describe a smartphone-based origami µPAD for the quantitative determination of glucose in blood samples based on the glucose oxidase-catalyzed oxidation of glucose leading to hydrogen peroxide, which is then detected by means of the luminol/hexacyanoferrate(III) chemiluminescent (CL) system. By exploiting the foldable µPAD format, a two-step analytical procedure has been implemented. First, the diluted blood sample was added, and hydrogen peroxide was accumulated, then the biosensor was folded, and a transport buffer was added to bring hydrogen peroxide in contact with CL reagents, thus promoting the CL reaction. To enable POC applicability, the reagents required for the assay were preloaded in the µPAD so that no chemicals handling was required, and a 3D-printed portable device was developed for measuring the CL emission using the smartphone’s CMOS camera. The µPAD was stable for 30-day storage at room temperature and the assay, displaying a limit of detection of 10 µmol L−1, proved able to identify both hypoglycemic and hyperglycemic blood samples in less than 20 min. Full article
(This article belongs to the Special Issue Enzyme-Based Biosensors and Their Applications)
►▼ Show Figures

Figure 1

10 pages, 2768 KiB  
Communication
Mesoporous One-Component Gold Microshells as 3D SERS Substrates
by Anna S. Vikulina, Inna Y. Stetsyura, M. Serdar Onses, Erkan Yilmaz, Andre G. Skirtach and Dmitry Volodkin
Biosensors 2021, 11(10), 380; https://doi.org/10.3390/bios11100380 - 9 Oct 2021
Cited by 5 | Viewed by 2341
Abstract
Surface-enhanced Raman scattering (SERS) is a powerful analytical tool for label-free analysis that has found a broad spectrum of applications in material, chemical, and biomedical sciences. In recent years, a great interest has been witnessed in the rational design of SERS substrates to [...] Read more.
Surface-enhanced Raman scattering (SERS) is a powerful analytical tool for label-free analysis that has found a broad spectrum of applications in material, chemical, and biomedical sciences. In recent years, a great interest has been witnessed in the rational design of SERS substrates to amplify Raman signals and optionally allow for the selective detection of analytes, which is especially essential and challenging for biomedical applications. In this study, hard templating of noble metals is proposed as a novel approach for the design of one-component tailor-made SERS platforms. Porous Au microparticles were fabricated via dual ex situ adsorption of Au nanoparticles and in situ reduction of HAuCl4 on mesoporous sacrificial microcrystals of vaterite CaCO3. Elimination of the microcrystals at mild conditions resulted in the formation of stable mesoporous one-component Au microshells. SERS performance of the microshells at very low 0.4 µW laser power was probed using rhodamine B and bovine serum albumin showing enhancement factors of 2 × 108 and 8 × 108, respectively. The proposed strategy opens broad avenues for the design and scalable fabrication of one-component porous metal particles that can serve as superior SERS platforms possessing both excellent plasmonic properties and the possibility of selective inclusion of analyte molecules and/or SERS nanotags for highly specific SERS analysis. Full article
(This article belongs to the Special Issue Advances in Nanoporous Materials for Biosensing Applications)
►▼ Show Figures

Figure 1

12 pages, 1517 KiB  
Article
Alginate Bead Biosystem for the Determination of Lactate in Sweat Using Image Analysis
by Sandra Garcia-Rey, Edilberto Ojeda, Udara Bimendra Gunatilake, Lourdes Basabe-Desmonts and Fernando Benito-Lopez
Biosensors 2021, 11(10), 379; https://doi.org/10.3390/bios11100379 - 9 Oct 2021
Cited by 19 | Viewed by 3213
Abstract
Lactate is present in sweat at high concentrations, being a metabolite of high interest in sport science and medicine. Therefore, the potential to determine lactate concentrations in physiological fluids, at the point of need with minimal invasiveness, is very valuable. In this work, [...] Read more.
Lactate is present in sweat at high concentrations, being a metabolite of high interest in sport science and medicine. Therefore, the potential to determine lactate concentrations in physiological fluids, at the point of need with minimal invasiveness, is very valuable. In this work, the synthesis and performance of an alginate bead biosystem was investigated. Artificial sweat with different lactate concentrations was used as a proof of concept. The lactate detection was based on a colorimetric assay and an image analysis method using lactate oxidase, horseradish peroxidase and tetramethyl benzidine as the reaction mix. Lactate in artificial sweat was detected with a R² = 0.9907 in a linear range from 10 mM to 100 mM, with a limit of detection of 6.4 mM and a limit of quantification of 21.2 mM. Real sweat samples were used as a proof of concept to test the performance of the biosystem, obtaining a lactate concentration of 48 ± 3 mM. This novel sensing configuration, using alginate beads, gives a fast and reliable method for lactate sensing, which could be integrated into more complex analytical systems. Full article
(This article belongs to the Special Issue Biosensors for Body Fluid Analysis)
►▼ Show Figures

Figure 1

13 pages, 2482 KiB  
Article
Aptamer Embedded Arch-Cruciform DNA Assemblies on 2-D VS2 Scaffolds for Sensitive Detection of Breast Cancer Cells
by Jinfeng Quan, Yihan Wang, Jialei Zhang, Kejing Huang, Xuemei Wang and Hui Jiang
Biosensors 2021, 11(10), 378; https://doi.org/10.3390/bios11100378 - 8 Oct 2021
Cited by 9 | Viewed by 2796
Abstract
Arch-cruciform DNA are self-assembled on AuNPs/VS2 scaffold as a highly sensitive and selective electrochemical biosensor for michigan cancer foundation-7 (MCF-7) breast cancer cells. In the construction, arch DNA is formed using two single-strand DNA sequences embedded with the aptamer for MCF-7 cells. [...] Read more.
Arch-cruciform DNA are self-assembled on AuNPs/VS2 scaffold as a highly sensitive and selective electrochemical biosensor for michigan cancer foundation-7 (MCF-7) breast cancer cells. In the construction, arch DNA is formed using two single-strand DNA sequences embedded with the aptamer for MCF-7 cells. In the absence of MCF-7 cells, a cruciform DNA labeled with three terminal biotin is bound to the top of arch DNA, which further combines with streptavidin-labeled horseradish peroxidase (HRP) to catalyze the hydroquinone-H2O2 reaction on the electrode surface. The presence of MCF-7 cells can release the cruciform DNA and reduce the amount of immobilized HRP, thus effectively inhibiting enzyme-mediated electrocatalysis. The electrochemical response of the sensor is negatively correlated with the concentration of MCF-7 cells, with a linear range of 10~1 × 105 cells/mL, and a limit of detection as low as 5 cells/mL (S/N = 3). Through two-dimensional materials and enzyme-based dual signal amplification, this biosensor may pave new ways for the highly sensitive detection of tumor cells in real samples. Full article
(This article belongs to the Special Issue Biosensing and Bioimaging: Trends and Perspective)
►▼ Show Figures

Figure 1

11 pages, 1748 KiB  
Article
High Sensitivity Terahertz Biosensor Based on Mode Coupling of a Graphene/Bragg Reflector Hybrid Structure
by Yamei Liu, Qiwen Zheng, Hongxia Yuan, Shenping Wang, Keqiang Yin, Xiaoyu Dai, Xiao Zou and Leyong Jiang
Biosensors 2021, 11(10), 377; https://doi.org/10.3390/bios11100377 - 8 Oct 2021
Cited by 7 | Viewed by 2867
Abstract
In this work, a high-sensitivity terahertz (THz) biosensor is achieved by using a graphene/Bragg reflector hybrid structure. This high-sensitivity THz biosensor is developed from the sharp Fano resonance transmission peak created by coupling the graphene Tamm plasmons (GTPs) mode to a defect mode. [...] Read more.
In this work, a high-sensitivity terahertz (THz) biosensor is achieved by using a graphene/Bragg reflector hybrid structure. This high-sensitivity THz biosensor is developed from the sharp Fano resonance transmission peak created by coupling the graphene Tamm plasmons (GTPs) mode to a defect mode. It is found that the proposed THz biosensor is highly sensitive to the Fermi energy of graphene, as well as the thickness and refractive index of the sensing medium. Through specific parameter settings, the composite structure can achieve both a liquid biosensor and a gas biosensor. For the liquid biosensor, the maximum sensitivity of > 1000 °/RIU is obtained by selecting appropriate parameters. We believe the proposed layered hybrid structure has the potential to fabricate graphene-based high-sensitivity biosensors. Full article
(This article belongs to the Special Issue Optical Biosensor with 2D Materials and Metamaterials)
►▼ Show Figures

Figure 1

13 pages, 2448 KiB  
Article
Design and Analysis of a Single System of Impedimetric Biosensors for the Detection of Mosquito-Borne Viruses
by Fahmida Nasrin, Kenta Tsuruga, Doddy Irawan Setyo Utomo, Ankan Dutta Chowdhury and Enoch Y. Park
Biosensors 2021, 11(10), 376; https://doi.org/10.3390/bios11100376 - 7 Oct 2021
Cited by 11 | Viewed by 2963
Abstract
The treatment for mosquito-borne viral diseases such as dengue virus (DENV), zika virus (ZIKV), and chikungunya virus (CHIKV) has become difficult due to delayed diagnosis processes. In addition, sharing the same transmission media and similar symptoms at the early stage of infection of [...] Read more.
The treatment for mosquito-borne viral diseases such as dengue virus (DENV), zika virus (ZIKV), and chikungunya virus (CHIKV) has become difficult due to delayed diagnosis processes. In addition, sharing the same transmission media and similar symptoms at the early stage of infection of these diseases has become more critical for early diagnosis. To overcome this, a common platform that can identify the virus with high sensitivity and selectivity, even for the different serotypes, is in high demand. In this study, we have attempted an electrochemical impedimetric method to detect the ZIKV, DENV, and CHIKV using their corresponding antibody-conjugated sensor electrodes. The significance of this method is emphasized on the fabrication of a common matrix of gold–polyaniline and sulfur, nitrogen-doped graphene quantum dot nanocomposites (Au-PAni-N,S-GQDs), which have a strong impedimetric response based only on the conjugated antibody, resulting in minimum cross-reactivity for the detection of various mosquito-borne viruses, separately. As a result, four serotypes of DENV and ZIKV, and CHIKV have been detected successfully with an LOD of femtogram mL−1. Full article
(This article belongs to the Special Issue Electrical and Electro-Optical Biosensors)
►▼ Show Figures

Figure 1

Show export options expand_more Show export options expand_less
Select all
Export citation of selected articles as:
 
Displaying articles 1-57
Previous Issue
Next Issue
Back to TopTop