Biosensors

18 pages, 6050 KiB

Open AccessArticle

Investigation of a Camera-Based Contactless Pulse Oximeter with Time-Division Multiplex Illumination Applied on Piglets for Neonatological Applications

by René Thull, Sybelle Goedicke-Fritz, Daniel Schmiech, Aly Marnach, Simon Müller, Christina Körbel, Matthias W. Laschke, Erol Tutdibi, Nasenien Nourkami-Tutdibi, Elisabeth Kaiser, Regine Weber, Michael Zemlin and Andreas R. Diewald

Biosensors 2024, 14(9), 437; https://doi.org/10.3390/bios14090437 - 9 Sep 2024

Abstract

(1) Objective: This study aims to lay a foundation for noncontact intensive care monitoring of premature babies. (2) Methods: Arterial oxygen saturation and heart rate were measured using a monochrome camera and time-division multiplex controlled lighting at three different wavelengths (660 nm, 810 [...] Read more.

(1) Objective: This study aims to lay a foundation for noncontact intensive care monitoring of premature babies. (2) Methods: Arterial oxygen saturation and heart rate were measured using a monochrome camera and time-division multiplex controlled lighting at three different wavelengths (660 nm, 810 nm and 940 nm) on a piglet model. (3) Results: Using this camera system and our newly designed algorithm for further analysis, the detection of a heartbeat and the calculation of oxygen saturation were evaluated. In motionless individuals, heartbeat and respiration were separated clearly during light breathing and with only minor intervention. In this case, the mean difference between noncontact and contact saturation measurements was 0.7% (RMSE = 3.8%, MAE = 2.93%). (4) Conclusions: The new sensor was proven effective under ideal animal experimental conditions. The results allow a systematic improvement for the further development of contactless vital sign monitoring systems. The results presented here are a major step towards the development of an incubator with noncontact sensor systems for use in the neonatal intensive care unit. Full article

(This article belongs to the Special Issue Selected Papers from the 4th International Electronic Conference on Biosensors (IECB 2024))

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12 pages, 2070 KiB

Open AccessArticle

Ultrasensitive Electrochemical Biosensor for Rapid Screening of Chemicals with Estrogenic Effect

by Ruixin Li, Jin Li, Xianbo Lu, Fanli Meng and Jiping Chen

Biosensors 2024, 14(9), 436; https://doi.org/10.3390/bios14090436 - 9 Sep 2024

Abstract

Estrogenic chemicals are widely distributed and structurally diverse. They primarily disrupt estrogen-related metabolism in animals or humans by mimicking the agonistic receptor effects of natural estrogens, thereby influencing the transcription of estrogen receptors to regulate their quantity and sensitivity. This disruption of estrogen-related [...] Read more.

Estrogenic chemicals are widely distributed and structurally diverse. They primarily disrupt estrogen-related metabolism in animals or humans by mimicking the agonistic receptor effects of natural estrogens, thereby influencing the transcription of estrogen receptors to regulate their quantity and sensitivity. This disruption of estrogen-related metabolism can lead to estrogen-related effects, posing risks to biological health, emphasizing the urgent need for simple and effective methods to screen compounds with estrogenic effects. Herein, a new electrochemical biological effect biosensor based on human estrogen receptor α (hERα) is developed, which uses hERα as the biorecognition element and employs the electroactive horseradish peroxidase (HRP) labeled 17β-estradiol (E2) multifunctional conjugate HRP-E2 as the signal-boosting element and ligand competition agent. Based on the specific ligand–receptor interaction principle between the target and nuclear receptor, by allowing the test compound to compete with HRP-E2 conjugate for binding to hERα and testing the electrocatalytic signal of the conjugate that fails to bind to the hERα estrogen receptor, rapid screening and quantitative detection of chemical substances with estrogenic effect have been achieved. The biosensor shows a wide linear range of 40 pM to 40 nM with a detection limit of 17 pM (S/N = 3) for E2, and the detection limit is 2 orders of magnitude better than that of the previously reported sensors. The biosensor based on ligand–receptor binding can not only quantitatively analyze the typical estrogen E2, but also evaluate the relative estrogen effect strength of other estrogen compounds, which has good stability and selectivity. This electrochemical sensing platform displays its promising potential for rapid screening and quantitative detection of chemicals with estrogenic effects. Full article

(This article belongs to the Special Issue Electrochemical and Fluorescent Biosensors: Novel Strategies, Methods, and Materials II)

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17 pages, 4247 KiB

Open AccessArticle

Advanced Liver-on-a-Chip Model for Evaluating Drug Metabolism and Hepatotoxicity

by Sonia Frojdenfal and Agnieszka Zuchowska

Biosensors 2024, 14(9), 435; https://doi.org/10.3390/bios14090435 - 6 Sep 2024

Abstract

The liver has many important functions, including the biotransformation of drugs and detoxification of the human organism. As such, it is also exposed to many harmful substances, which leads to disorders and diseases such as cirrhosis. For these reasons, it seems important to [...] Read more.

The liver has many important functions, including the biotransformation of drugs and detoxification of the human organism. As such, it is also exposed to many harmful substances, which leads to disorders and diseases such as cirrhosis. For these reasons, it seems important to consider liver metabolism and the direct effects on the liver when evaluating the efficacy of new drugs. Accordingly, we have developed an advanced in vitro liver model using an organ-on-a-chip approach that replicates many of the morphological and functional features of the liver in vivo. The model we created can metabolize drugs, which we demonstrated using two widely used anticancer drugs, 5-fluorouracil (5FU) and capecitabine (CAP). In addition, to the best of our knowledge, we are the first who evaluate the direct effects of these drugs not only on the viability of liver model-building cells but on their functions, such as cytochrome P450 activity and albumin production. Our study brings new hope to properly evaluating drug efficacy at the in vitro level. Full article

(This article belongs to the Special Issue Biosensor Nanoengineering: Design, Operation and Implementation)

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33 pages, 10567 KiB

Open AccessArticle

Microwave Technique for Linear Skull Fracture Detection—Simulation and Experimental Study Using Realistic Human Head Models

by Mariella Särestöniemi, Daljeet Singh, Mikael von und zu Fraunberg and Teemu Myllylä

Biosensors 2024, 14(9), 434; https://doi.org/10.3390/bios14090434 - 6 Sep 2024

Abstract

Microwave (MW) sensing is regarded as a promising technique for various medical monitoring and diagnostic applications due to its numerous advantages and the potential to be developed into a portable device for use outside hospital settings. The detection of skull fractures and the [...] Read more.

Microwave (MW) sensing is regarded as a promising technique for various medical monitoring and diagnostic applications due to its numerous advantages and the potential to be developed into a portable device for use outside hospital settings. The detection of skull fractures and the monitoring of their healing process would greatly benefit from a rapidly and frequently usable application that can be employed outside the hospital. This paper presents a simulation- and experiment-based study on skull fracture detection with the MW technique using realistic models for the first time. It also presents assessments on the most promising frequency ranges for skull fracture detection within the Industrial, Scientific and Medical (ISM) and ultrawideband (UWB) ranges. Evaluations are carried out with electromagnetic simulations using different head tissue layer models corresponding to different locations in the human head, as well as an anatomically realistic human head simulation model. The measurements are conducted with a real human skull combined with tissue phantoms developed in our laboratory. The comprehensive evaluations show that fractures cause clear differences in antenna and channel parameters (S11 and S21). The difference in S11 is 0.1–20 dB and in S21 is 0.1–30 dB, depending on the fracture width and location. Skull fractures with a less than 1 mm width can be detected with microwaves at different fracture locations. The detectability is frequency dependent. Power flow representations illustrate how fractures impact on the signal propagation at different frequencies. MW-based detection of skull fractures provides the possibility to (1) detect fractures using a safe and low-cost portable device, (2) monitor the healing-process of fractures, and (3) bring essential information for emerging portable MW-based diagnostic applications that can detect, e.g., strokes. Full article

(This article belongs to the Special Issue Medical Imaging and Biosensing)

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14 pages, 7836 KiB

Open AccessReview

Recent Progress in the Synthesis of 3D Complex Plasmonic Intragap Nanostructures and Their Applications in Surface-Enhanced Raman Scattering

by Li Ma, Keyi Zhou, Xinyue Wang, Jiayue Wang, Ruyu Zhao, Yifei Zhang and Fang Cheng

Biosensors 2024, 14(9), 433; https://doi.org/10.3390/bios14090433 - 6 Sep 2024

Abstract

Plasmonic intragap nanostructures (PINs) have garnered intensive attention in Raman-related analysis due to their exceptional ability to enhance light–matter interactions. Although diverse synthetic strategies have been employed to create these nanostructures, the emphasis has largely been on PINs with simple configurations, which often [...] Read more.

Plasmonic intragap nanostructures (PINs) have garnered intensive attention in Raman-related analysis due to their exceptional ability to enhance light–matter interactions. Although diverse synthetic strategies have been employed to create these nanostructures, the emphasis has largely been on PINs with simple configurations, which often fall short in achieving effective near-field focusing. Three-dimensional (3D) complex PINs, distinguished by their intricate networks of internal gaps and voids, are emerging as superior structures for effective light trapping. These structures facilitate the generation of hot spots and hot zones that are essential for enhanced near-field focusing. Nevertheless, the synthesis techniques for these complex structures and their specific impacts on near-field focusing are not well-documented. This review discusses the recent advancements in the synthesis of 3D complex PINs and their applications in surface-enhanced Raman scattering (SERS). We begin by describing the foundational methods for fabricating simple PINs, followed by a discussion on the rational design strategies aimed at developing 3D complex PINs with superior near-field focusing capabilities. We also evaluate the SERS performance of various 3D complex PINs, emphasizing their advanced sensing capabilities. Lastly, we explore the future perspective of 3D complex PINs in SERS applications. Full article

(This article belongs to the Special Issue Functional Nanomaterials for Biosensing (Volume II))

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13 pages, 4393 KiB

Open AccessArticle

A Cost-Effective and Easy-to-Fabricate Conductive Velcro Dry Electrode for Durable and High-Performance Biopotential Acquisition

by Jun Guo, Xuanqi Wang, Ruiyu Bai, Zimo Zhang, Huazhen Chen, Kai Xue, Chuang Ma, Dawei Zang, Erwei Yin, Kunpeng Gao and Bowen Ji

Biosensors 2024, 14(9), 432; https://doi.org/10.3390/bios14090432 - 6 Sep 2024

Abstract

Compared with the traditional gel electrode, the dry electrode is being taken more seriously in bioelectrical recording because of its easy preparation, long-lasting ability, and reusability. However, the commonly used dry AgCl electrodes and silver cloth electrodes are generally hard to record through [...] Read more.

Compared with the traditional gel electrode, the dry electrode is being taken more seriously in bioelectrical recording because of its easy preparation, long-lasting ability, and reusability. However, the commonly used dry AgCl electrodes and silver cloth electrodes are generally hard to record through hair due to their flat contact surface. Claw electrodes can contact skin through hair on the head and body, but the internal claw structure is relatively hard and causes discomfort after being worn for a few hours. Here, we report a conductive Velcro electrode (CVE) with an elastic hook hair structure, which can collect biopotential through body hair. The elastic hooks greatly reduce discomfort after long-time wearing and can even be worn all day. The CVE electrode is fabricated by one-step immersion in conductive silver paste based on the cost-effective commercial Velcro, forming a uniform and durable conductive coating on a cluster of hook microstructures. The electrode shows excellent properties, including low impedance (15.88 kΩ @ 10 Hz), high signal-to-noise ratio (16.0 dB), strong water resistance, and mechanical resistance. After washing in laundry detergent, the impedance of CVE is still 16% lower than the commercial AgCl electrodes. To verify the mechanical strength and recovery capability, we conducted cyclic compression experiments. The results show that the displacement change of the electrode hook hair after 50 compression cycles was still less than 1%. This electrode provides a universal acquisition scheme, including effective acquisition of different parts of the body with or without hair. Finally, the gesture recognition from electromyography (EMG) by the CVE electrode was applied with accuracy above 90%. The CVE proposed in this study has great potential and promise in various human–machine interface (HMI) applications that employ surface biopotential signals on the body or head with hair. Full article

(This article belongs to the Special Issue Advances in Flexible Bioelectronics and Intelligent Biosensing Systems)

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14 pages, 2357 KiB

Open AccessArticle

Comparative Analysis of QCM and Electrochemical Aptasensors for SARS-CoV-2 Detection

by Katarína Nemčeková, Jana Korčeková, Veronika Svitková, Denis Baraniak, Michaela Domšicová, Eva Melníková, Michaela Hornychová, Viktória Szebellaiová, Miroslav Gál and Alexandra Poturnayová

Biosensors 2024, 14(9), 431; https://doi.org/10.3390/bios14090431 - 6 Sep 2024

Abstract

The rapid and accurate detection of SARS-CoV-2, particularly its spike receptor-binding domain (S-RBD), was crucial for managing the COVID-19 pandemic. This study presents the development and optimization of two types of aptasensors: quartz crystal microbalance (QCM) and electrochemical sensors, both employing thiol-modified DNA [...] Read more.

The rapid and accurate detection of SARS-CoV-2, particularly its spike receptor-binding domain (S-RBD), was crucial for managing the COVID-19 pandemic. This study presents the development and optimization of two types of aptasensors: quartz crystal microbalance (QCM) and electrochemical sensors, both employing thiol-modified DNA aptamers for S-RBD detection. The QCM aptasensor demonstrated exceptional sensitivity, achieved by optimizing aptamer concentration, buffer composition, and pre-treatment conditions, with a limit of detection (LOD) of 0.07 pg/mL and a linear range from 1 pg/mL to 0.1 µg/mL, and a significant frequency change was observed upon target binding. The electrochemical aptasensor, designed for rapid and efficient preparation, utilized a one-step modification process that reduced the preparation time to 2 h while maintaining high sensitivity and specificity. Electrochemical impedance spectroscopy (EIS) enabled the detection of S-RBD concentrations as low as 132 ng/mL. Both sensors exhibited high specificity, with negligible non-specific interactions observed in the presence of competing proteins. Additionally, the QCM aptasensor’s functionality and stability were verified in biological fluids, indicating its potential for real-world applications. This study highlights the comparative advantages of QCM and electrochemical aptasensors in terms of preparation time, sensitivity, and specificity, offering valuable insights for the development of rapid, sensitive, and specific diagnostic tools for the detection of SARS-CoV-2 and other viruses. Full article

(This article belongs to the Special Issue Aptamer-Based Biosensing and Bioassays)

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19 pages, 20339 KiB

Open AccessArticle

Enhancing Colorimetric Detection of Nucleic Acids on Nitrocellulose Membranes: Cutting-Edge Applications in Diagnostics and Forensics

by Nidhi Subhashini, Yannick Kerler, Marcus M. Menger, Olga Böhm, Judith Witte, Christian Stadler and Alexander Griberman

Biosensors 2024, 14(9), 430; https://doi.org/10.3390/bios14090430 - 5 Sep 2024

Abstract

This study re-introduces a protein-free rapid test method for nucleic acids on paper based lateral flow assays utilizing special multichannel nitrocellulose membranes and DNA-Gold conjugates, achieving significantly enhanced sensitivity, easier protocols, reduced time of detection, reduced costs of production and advanced multiplexing possibilities. [...] Read more.

This study re-introduces a protein-free rapid test method for nucleic acids on paper based lateral flow assays utilizing special multichannel nitrocellulose membranes and DNA-Gold conjugates, achieving significantly enhanced sensitivity, easier protocols, reduced time of detection, reduced costs of production and advanced multiplexing possibilities. A protein-free nucleic acid-based lateral flow assay (NALFA) with a limit of detection of 1 pmol of DNA is shown for the first time. The total production duration of such an assay was successfully reduced from the currently known several days to just a few hours. The simplification and acceleration of the protocol make the method more accessible and practical for various applications. The developed method supports multiplexing, enabling the simultaneous detection of up to six DNA targets. This multiplexing capability is a significant improvement over traditional line tests and offers more comprehensive diagnostic potential in a single assay. The approach significantly reduces the run time compared to traditional line tests, which enhances the efficiency of diagnostic procedures. The protein-free aspect of this assay minimizes the prevalent complications of cross-reactivity in immunoassays especially in cases of multiplexing. It is also demonstrated that the NALFA developed in this study is amplification-free and hence does not rely on specialized technicians, nor does it involve labour-intensive steps like DNA extraction and PCR processes. Overall, this study presents a robust, efficient, and highly sensitive platform for DNA or RNA detection, addressing several limitations of current methods documented in the literature. The advancements in sensitivity, cost reduction, production time, and multiplexing capabilities mark a substantial improvement, holding great potential for various applications in diagnostics, forensics, and molecular biology. Full article

(This article belongs to the Section Biosensors and Healthcare)

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9 pages, 6416 KiB

Open AccessCommunication

Tumor Microenvironment Based on Extracellular Matrix Hydrogels for On-Chip Drug Screening

by Xiaoyan Liu, Jinxiong Cheng and Yingcan Zhao

Biosensors 2024, 14(9), 429; https://doi.org/10.3390/bios14090429 - 5 Sep 2024

Abstract

Recent advances in three-dimensional (3D) culturing and nanotechnology offer promising pathways to overcome the limitations of drug screening, particularly for tumors like neuroblastoma. In this study, we develop a high-throughput microfluidic chip that integrates a concentration gradient generator (CGG) with a 3D co-culture [...] Read more.

Recent advances in three-dimensional (3D) culturing and nanotechnology offer promising pathways to overcome the limitations of drug screening, particularly for tumors like neuroblastoma. In this study, we develop a high-throughput microfluidic chip that integrates a concentration gradient generator (CGG) with a 3D co-culture system, constructing the vascularized microenvironment in tumors by co-culturing neuroblastoma (SY5Y cell line) and human brain microvascular endothelial cells (HBMVECs) within a decellularized extracellular matrix (dECM) hydrogels. The automated platform enhances the simulation of the tumor microenvironment and allows for the precise control of the concentrations of nanomedicines, which is crucial for evaluating therapeutic efficacy. The findings demonstrate that the high-throughput platform can significantly accelerate drug discovery. It efficiently screens and analyzes drug interactions in a biologically relevant setting, potentially revolutionizing the drug screening process. Full article

(This article belongs to the Special Issue Biochips and Biosensors for Health-Care and Diagnostics)

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14 pages, 5432 KiB

Open AccessArticle

Mitochondrial Labeling with Mulberrin-Cy3: A New Fluorescent Probe for Live Cell Visualization

by Gangxiang Yuan, Yiwei Luo, Peng Qian and Ningjia He

Biosensors 2024, 14(9), 428; https://doi.org/10.3390/bios14090428 - 5 Sep 2024

Abstract

Mitochondria, crucial intracellular organelles, are central to energy metabolism, signal transduction, apoptosis, calcium homeostasis, and a myriad of other biological processes, making them a focal point in diverse research fields. The capacity to fluorescently label and visually track mitochondria is crucial for understanding [...] Read more.

Mitochondria, crucial intracellular organelles, are central to energy metabolism, signal transduction, apoptosis, calcium homeostasis, and a myriad of other biological processes, making them a focal point in diverse research fields. The capacity to fluorescently label and visually track mitochondria is crucial for understanding their biological roles. We present mulberrin-Cy3, a novel small molecule fluorescent probe that selectively labels mitochondria in animal cells, including cancer cells, with relative ease. This protocol details the synthesis of mulberrin-Cy3 and its use for visualizing mitochondria in living cells. The synthesis is straightforward and time-efficient, and the labeling method is more accessible than traditional approaches, providing a cost-effective option for mitochondrial visualization at room temperature. The labeling is rapid, with effective labeling achieved within 5 min of incubation. The fluorescent signal is stable and brighter, offering a significant advantage over existing methods. Mulberrin-Cy3 represents a promising mitochondrial labeling compound, providing researchers with a novel experimental tool to explore the complex biological functions of mitochondria. This innovation has the potential to significantly advance our comprehension of mitochondrial dynamics and their role in cellular health and disease. Full article

(This article belongs to the Special Issue Probes for Biosensing and Bioimaging)

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9 pages, 3799 KiB

Open AccessCommunication

The Assessment of Methyl Methanesulfonate Absorption by Amphipods from the Environment Using Lux-Biosensors

by Uliana S. Novoyatlova, Anna A. Kudryavtseva, Sergey V. Bazhenov, Anna A. Utkina, Vadim V. Fomin, Shamil A. Nevmyanov, Bagila S. Zhoshibekova, Maria A. Fedyaeva, Mikhail Y. Kolobov and Ilya V. Manukhov

Biosensors 2024, 14(9), 427; https://doi.org/10.3390/bios14090427 - 5 Sep 2024

Abstract

The ability of aquatic mesofauna representatives involved in trophic chains to sorb and accumulate toxicants is important for understanding the functioning of aquatic ecosystems and for fishing industry. This study investigated the capacity of marine amphipod Gammarus oceanicus and freshwater amphipods Eulimnogammarus vittatus [...] Read more.

The ability of aquatic mesofauna representatives involved in trophic chains to sorb and accumulate toxicants is important for understanding the functioning of aquatic ecosystems and for fishing industry. This study investigated the capacity of marine amphipod Gammarus oceanicus and freshwater amphipods Eulimnogammarus vittatus and Gammarus lacustris to absorb the DNA-alkylating agent methyl methanesulfonate (MMS). The presence of alkylating agents in the environment and in the tissues of the amphipods was determined using whole-cell lux-biosensor Escherichia coli MG1655 pAlkA-lux, in which the luxCDABE genes from Photorhabdus luminescens, enabling the luminescence of the cell culture, are controlled by the P_alkA promoter of DNA glycosylase. It was shown that within one day of incubation in water containing MMS at a concentration above 10 μM, the amphipods absorbed the toxicant and their tissues produce more alkylation damage to biosensor cells than the surrounding water. Concentrations of MMS above 1 mM in the environment caused the death of the amphipods before the toxicant could be significantly concentrated in their tissues. The sensitivity and the capacity to absorb MMS were found to be approximately the same for the marine amphipod G. oceanicus and the freshwater amphipods E. vittatus and G. lacustris. Full article

(This article belongs to the Section Environmental Biosensors and Biosensing)

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12 pages, 41276 KiB

Open AccessArticle

Optimization of Nanowell-Based Label-Free Impedance Biosensor Based on Different Nanowell Structures

by Ali Fardoost, Hassan Raji and Mehdi Javanmard

Biosensors 2024, 14(9), 426; https://doi.org/10.3390/bios14090426 - 4 Sep 2024

Abstract

Nanowell-based impedance-based label-free biosensors have demonstrated significant advantages in sensitivity, simplicity, and accuracy for detecting cancer biomarkers and macromolecules compared to conventional impedance-based biosensors. Although nanowell arrays have previously been employed for biomarker detection, a notable limitation exists in the photolithography step of [...] Read more.

Nanowell-based impedance-based label-free biosensors have demonstrated significant advantages in sensitivity, simplicity, and accuracy for detecting cancer biomarkers and macromolecules compared to conventional impedance-based biosensors. Although nanowell arrays have previously been employed for biomarker detection, a notable limitation exists in the photolithography step of their fabrication process, leading to a reduced efficiency rate. Historically, the diameter of these nanowells has been 2 μm. To address this issue, we propose alternative geometries for nanowells that feature larger surface areas while maintaining a similar circumference, thereby enhancing the fabrication efficiency of the biosensors. We investigated three geometries: tube, spiral, and quatrefoil. Impedance measurements of the samples were conducted at 10 min intervals using a lock-in amplifier. The study utilized interleukin-6 (IL-6) antibodies and antigens/proteins at a concentration of 100 nM as the target macromolecules. The results indicated that tube-shaped nanowells exhibited the highest sensitivity for detecting IL-6 protein, with an impedance change of 9.55%. In contrast, the spiral, quatrefoil, and circle geometries showed impedance changes of 0.91%, 0.95%, and 1.62%, respectively. Therefore, the tube-shaped nanowell structure presents a promising alternative to conventional nanowell arrays for future studies, potentially enhancing the efficiency and sensitivity of biosensor fabrication. Full article

(This article belongs to the Special Issue Biosensors Based on Microfluidic Devices-2nd Edition)

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29 pages, 3320 KiB

Open AccessReview

Revolutionizing Drug Discovery: The Impact of Distinct Designs and Biosensor Integration in Microfluidics-Based Organ-on-a-Chip Technology

by Sheng Yuan, Huipu Yuan, David C. Hay, Huan Hu and Chaochen Wang

Biosensors 2024, 14(9), 425; https://doi.org/10.3390/bios14090425 - 3 Sep 2024

Abstract

Traditional drug development is a long and expensive process with high rates of failure. This has prompted the pharmaceutical industry to seek more efficient drug development frameworks, driving the emergence of organ-on-a-chip (OOC) based on microfluidic technologies. Unlike traditional animal experiments, OOC systems [...] Read more.

Traditional drug development is a long and expensive process with high rates of failure. This has prompted the pharmaceutical industry to seek more efficient drug development frameworks, driving the emergence of organ-on-a-chip (OOC) based on microfluidic technologies. Unlike traditional animal experiments, OOC systems provide a more accurate simulation of human organ microenvironments and physiological responses, therefore offering a cost-effective and efficient platform for biomedical research, particularly in the development of new medicines. Additionally, OOC systems enable quick and real-time analysis, high-throughput experimentation, and automation. These advantages have shown significant promise in enhancing the drug development process. The success of an OOC system hinges on the integration of specific designs, manufacturing techniques, and biosensors to meet the need for integrated multiparameter datasets. This review focuses on the manufacturing, design, sensing systems, and applications of OOC systems, highlighting their design and sensing capabilities, as well as the technical challenges they currently face. Full article

(This article belongs to the Special Issue Microfluidics for Biomedical Applications (Volume II))

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14 pages, 2684 KiB

Open AccessArticle

Advanced Imaging Methodology in Bacterial Biofilms with a Fluorescent Enzymatic Sensor for pepN Activity

by Javier Valverde-Pozo, Jose M. Paredes, María Eugenia García-Rubiño, María Dolores Girón, Rafael Salto, Jose M. Alvarez-Pez and Eva M. Talavera

Biosensors 2024, 14(9), 424; https://doi.org/10.3390/bios14090424 - 3 Sep 2024

Abstract

This research explores the use of the pepN activity fluorescent sensor DCM-Ala in bacterial biofilms, emphasizing its significance due to the critical role of biofilms in various biological processes. Advanced imaging techniques were employed to visualize pepN activity, introducing a novel approach to [...] Read more.

This research explores the use of the pepN activity fluorescent sensor DCM-Ala in bacterial biofilms, emphasizing its significance due to the critical role of biofilms in various biological processes. Advanced imaging techniques were employed to visualize pepN activity, introducing a novel approach to examining biofilm maturity. We found that the overexpression of pepN increases the ability of E. coli to form biofilm. The findings demonstrate varying levels of pepN activity throughout biofilm development, suggesting potential applications in biofilm research and management. The results indicate that the fluorescent emission from this sensor could serve as a reliable indicator of biofilm maturity, and the imaging techniques developed could enhance our understanding and control of biofilm-related processes. This work highlights the importance of innovative methods in biofilm study and opens new avenues for utilizing chemical emissions in biofilm management. Full article

(This article belongs to the Special Issue Microbial Biosensor: From Design to Applications)

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24 pages, 761 KiB

Open AccessSystematic Review

Are Aptamer-Based Biosensors the Future of the Detection of the Human Gut Microbiome?—A Systematic Review and Meta-Analysis

by Maria João Moreira, Manuela Pintado and José M. M. M. De Almeida

Biosensors 2024, 14(9), 423; https://doi.org/10.3390/bios14090423 - 2 Sep 2024

Abstract

The gut microbiome is shaped early in life by dietary and lifestyle factors. Specific compounds in the gut affect the growth of different bacterial species and the production of beneficial or harmful byproducts. Dysbiosis of the gut microbiome has been linked to various [...] Read more.

The gut microbiome is shaped early in life by dietary and lifestyle factors. Specific compounds in the gut affect the growth of different bacterial species and the production of beneficial or harmful byproducts. Dysbiosis of the gut microbiome has been linked to various diseases resulting from the presence of harmful bacteria and their byproducts. Existing methods for detecting microbial species, such as microscopic observation and molecular biological techniques, are costly, labor-intensive, and require skilled personnel. Biosensors, which integrate a recognition element, transducer, amplifier, signal processor, and display unit, can convert biological events into electronic signals. This review provides a comprehensive and systematic survey of scientific publications from 2018 to June 2024, obtained from ScienceDirect, PubMed, and Scopus databases. The aim was to evaluate the current state-of-the-art and identify knowledge gaps in the application of aptamer biosensors for the determination of gut microbiota. A total of 13 eligible publications were categorized based on the type of study: those using microbial bioreceptors (category 1) and those using aptamer bioreceptors (category 2) for the determination of gut microbiota. Point-of-care biosensors are being developed to monitor changes in metabolites that may lead to disease. They are well-suited for use in the healthcare system and offer an excellent alternative to traditional methods. Aptamers are gaining attention due to their stability, specificity, scalability, reproducibility, low production cost, and low immunogenicity. While there is limited research on using aptamers to detect human gut microbiota, they show promise for providing accurate, robust, and cost-effective diagnostic methods for monitoring the gut microbiome. Full article

(This article belongs to the Special Issue Aptamer-Based Biosensing and Bioassays)

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55 pages, 6871 KiB

Open AccessReview

Recent Progress in Biosensors for Depression Monitoring—Advancing Personalized Treatment

by Jiaju Yin, Xinyuan Jia, Haorong Li, Bingchen Zhao, Yi Yang and Tian-Ling Ren

Biosensors 2024, 14(9), 422; https://doi.org/10.3390/bios14090422 - 30 Aug 2024

Abstract

Depression is currently a major contributor to unnatural deaths and the healthcare burden globally, and a patient’s battle with depression is often a long one. Because the causes, symptoms, and effects of medications are complex and highly individualized, early identification and personalized treatment [...] Read more.

Depression is currently a major contributor to unnatural deaths and the healthcare burden globally, and a patient’s battle with depression is often a long one. Because the causes, symptoms, and effects of medications are complex and highly individualized, early identification and personalized treatment of depression are key to improving treatment outcomes. The development of wearable electronics, machine learning, and other technologies in recent years has provided more possibilities for the realization of this goal. Conducting regular monitoring through biosensing technology allows for a more comprehensive and objective analysis than previous self-evaluations. This includes identifying depressive episodes, distinguishing somatization symptoms, analyzing etiology, and evaluating the effectiveness of treatment programs. This review summarizes recent research on biosensing technologies for depression. Special attention is given to technologies that can be portable or wearable, with the potential to enable patient use outside of the hospital, for long periods. Full article

(This article belongs to the Special Issue Innovative Biosensing Technologies for Sustainable Healthcare)

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10 pages, 2607 KiB

Open AccessCommunication

Optical Interferometric Device for Rapid and Specific Detection of Biological Cells

by Sándor Valkai, Dániel Petrovszki, Zsombor Fáskerti, Margaréta Baumgärtner, Brigitta Biczók, Kira Dakos, Kevin Dósa, Berill B. Kirner, Anna E. Kocsis, Krisztina Nagy, István Andó and András Dér

Biosensors 2024, 14(9), 421; https://doi.org/10.3390/bios14090421 - 29 Aug 2024

Abstract

Here, we report a rapid and accurate optical method for detecting cells from liquid samples in a label-free manner. The working principle of the method is based on the interference of parts of a conical laser beam, coming from a single-mode optical fiber [...] Read more.

Here, we report a rapid and accurate optical method for detecting cells from liquid samples in a label-free manner. The working principle of the method is based on the interference of parts of a conical laser beam, coming from a single-mode optical fiber directly, and reflected from a flat glass surface. The glass is functionalized by antibodies against the cells to be detected from the liquid sample. Cells bound to that surface modify the reflected beam, and hence, change the resulting interference pattern, too. By registering and interpreting the variation in the image, the presence of cells from the sample can be detected. As for a demonstration, cell suspensions from a U937 cell line were used in glass chambers functionalized by antibodies (TMG6-5 (mIgG1)) to which the cells specifically bind. The limit of detection (LOD) of the method was also estimated. This proof-of-concept setup offers a cost-effective and easy-to-use way of rapid and specific detection of any type of cells (including pathogens) from suspensions (e.g., body fluids). The possible portability of the device predicts its applicability as a rapid test in clinical diagnostics. Full article

(This article belongs to the Special Issue Feature Paper in Biosensor and Bioelectronic Devices 2024)

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28 pages, 7558 KiB

Open AccessReview

Electrocatalysis in MOF Films for Flexible Electrochemical Sensing: A Comprehensive Review

by Suyuan Zhang, Min Wang, Xusheng Wang, Jun Song and Xue Yang

Biosensors 2024, 14(9), 420; https://doi.org/10.3390/bios14090420 - 28 Aug 2024

Abstract

Flexible electrochemical sensors can adhere to any bendable surface with conformal contact, enabling continuous data monitoring without compromising the surface’s dynamics. Among various materials that have been explored for flexible electronics, metal–organic frameworks (MOFs) exhibit dynamic responses to physical and chemical signals, offering [...] Read more.

Flexible electrochemical sensors can adhere to any bendable surface with conformal contact, enabling continuous data monitoring without compromising the surface’s dynamics. Among various materials that have been explored for flexible electronics, metal–organic frameworks (MOFs) exhibit dynamic responses to physical and chemical signals, offering new opportunities for flexible electrochemical sensing technologies. This review aims to explore the role of electrocatalysis in MOF films specifically designed for flexible electrochemical sensing applications, with a focus on their design, fabrication techniques, and applications. We systematically categorize the design and fabrication techniques used in preparing MOF films, including in situ growth, layer-by-layer assembly, and polymer-assisted strategies. The implications of MOF-based flexible electrochemical sensors are examined in the context of wearable devices, environmental monitoring, and healthcare diagnostics. Future research is anticipated to shift from traditional microcrystalline powder synthesis to MOF thin-film deposition, which is expected to not only enhance the performance of MOFs in flexible electronics but also improve sensing efficiency and reliability, paving the way for more robust and versatile sensor technologies. Full article

(This article belongs to the Special Issue Advanced Bioelectronics for Healthcare Monitoring and Disease Diagnosis)

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22 pages, 3860 KiB

Open AccessReview

Recent Developments in Personal Glucose Meters as Point-of-Care Testing Devices (2020–2024)

by Dan-Ni Yang, Shan Geng, Rong Jing and Hao Zhang

Biosensors 2024, 14(9), 419; https://doi.org/10.3390/bios14090419 - 27 Aug 2024

Abstract

Point-of-care testing (POCT) is a contemporary diagnostic approach characterized by its user-friendly nature, cost efficiency, environmental compatibility, and lack of reliance on professional experts. Therefore, it is widely used in clinical diagnosis and other analytical testing fields to meet the demand for rapid [...] Read more.

Point-of-care testing (POCT) is a contemporary diagnostic approach characterized by its user-friendly nature, cost efficiency, environmental compatibility, and lack of reliance on professional experts. Therefore, it is widely used in clinical diagnosis and other analytical testing fields to meet the demand for rapid and convenient testing. The application of POCT technology not only improves testing efficiency, but also brings convenience and benefits to the healthcare industry. The personal glucose meter (PGM) is a highly successful commercial POCT tool that has been widely used not only for glucose analysis, but also for non-glucose target detection. In this review, the recent advances from 2020 to 2024 in non-glucose target analysis for PGMs as POCT devices are summarized. The signal transduction strategies for non-glucose target analysis based on PGMs, including enzymatic transduction, nanocarrier transduction (enzyme or glucose), and glucose consumption transduction are briefly introduced. Meanwhile, the applications of PGMs in non-glucose target analysis are outlined, encompassing biomedical, environmental, and food analysis, along with other diverse applications. Finally, the prospects of and obstacles to employing PGMs as POCT tools for non-glucose target analysis are discussed. Full article

(This article belongs to the Special Issue Innovative Biosensing Technologies for Sustainable Healthcare)

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