Biosensors

18 pages, 2816 KB

Open AccessArticle

Electrochemical Detection of Aβ42 and Aβ40 at Attomolar Scale via Optimised Antibody Loading on Pyr-NHS-Functionalised 3D Graphene Foam Electrodes

by Muhsin Dogan, Sophia Nazir, David Jenkins, Yinghui Wei and Genhua Pan

Biosensors 2025, 15(12), 806; https://doi.org/10.3390/bios15120806 - 10 Dec 2025

Abstract

Alzheimer’s Disease (AD) is one of the most commonly seen neurodegenerative disorders, where early detection of its biomarkers is crucial for effective management. Conventional diagnostic methods are often expensive, time-consuming, and highly complex, which highlights an urgent need for point-of-care biosensing technology. In [...] Read more.

Alzheimer’s Disease (AD) is one of the most commonly seen neurodegenerative disorders, where early detection of its biomarkers is crucial for effective management. Conventional diagnostic methods are often expensive, time-consuming, and highly complex, which highlights an urgent need for point-of-care biosensing technology. In this work, we developed assays on three-dimensional (3D) graphene foam electrodes by functionalising them with a 1-Pyrenebutyric acid N-hydroxysuccinimide ester (Pyr-NHS) to enable effective antibody immobilisation for the detection of amyloid beta peptides (Aβ42 and Aβ40), key biomarkers for AD. Pyr-NHS linkers were used for stable functionalisation, followed by binding with Aβ42 and Aβ40 antibodies, and then bovine serum albumin (BSA) was employed as a blocking agent to minimise non-specific bindings on the electrode surface. Differential Pulse Voltammetry (DPV) measurements showed satisfactory stability over 12 days (RDS upper limit was <10%) and highly sensitive and specific detection of Aβ42 and Aβ40, with insignificant interference of tau217 protein. The biosensor exhibited a low limit of detection (LOD) with 252 aM for Aβ42 and 395 aM for Aβ40, covering 0.125 fM–1 nM and 0.125 fM–100 pM linear ranges, respectively. Further validation was conducted on spiked-diluted human plasma. This excellent analytical performance was attributed to the stable Pyr-NHS functionalisation, the 3D graphene foam enabling superior conductivity and a larger surface area on the working electrode, and the optimisation of antibody concentration for immobilisation. These promising results suggest that 3D graphene foam-based biosensors have considerable potential for early detection of AD biomarkers and developing cost-effective, portable, and reliable point-of-care devices. Full article

(This article belongs to the Section Biosensor and Bioelectronic Devices)

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33 pages, 5719 KB

Open AccessArticle

Transparent PEDOT:PSS/PDMS Leaf Tattoos for Multiplexed Plant Health Monitoring and Energy Harvesting

by Antonio Ruiz-Gonzalez, Harriet Kempson and Jim Haseloff

Biosensors 2025, 15(12), 805; https://doi.org/10.3390/bios15120805 - 9 Dec 2025

Abstract

The development of non-invasive sensors for individualised plant monitoring has become essential in smart farming to increase crop production. However current approaches are focused on the measurement of soil parameters instead, which cannot provide direct information about plant health. Moreover, equipment used for [...] Read more.

The development of non-invasive sensors for individualised plant monitoring has become essential in smart farming to increase crop production. However current approaches are focused on the measurement of soil parameters instead, which cannot provide direct information about plant health. Moreover, equipment used for the direct monitoring of plant health are costly with complex operation, hindering their use by the wider community of farmers. This work reports for the first time the development of a flexible and highly transparent sensor, based on thin conductive PEDOT:PSS/PDMS hybrid films directly deposited onto leaves. The films were fabricated by aerosol deposition and could operate under two different modes. The first mode is used for the determination of plant dryness and concentration of ions. The second mode is used as a triboelectric generator to generate up to 7.2 µW cm⁻² electrical power through the friction of the sensors with a leaf. The device was assembled using a low-cost (GBP < 70) microcontroller incorporating environmental sensors, and an intuitive interface was designed for operation. The final sensor could determine the ionic strength at the millimolar level by means of the impedance of electrodes. This performance allowed the study of differences in ionic content and water availability in tomato leaves during day–night cycles. The high stability of the sensors also allowed the long-term monitoring of plant health. Using this technology, a decrease in the leaf ionic strength due to the lack of electrolytes was observed after watering with deionised water for 2 days. Upon supplementation with fertiliser, the recorded ionic strength and leaf water content were similar to the original values prior to the use of DI water, demonstrating the applicability of the device in the early detection of stress factors that could decrease crop production. Full article

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

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19 pages, 2107 KB

Open AccessReview

Recent Advances in MXene-Based Screen-Printed Electrochemical Sensors for Point-of-Care Biomarker Detections

by Thao Thi Nguyen, Liang Zhou, Jinming Kong, Aiqin Luo, Zikai Hao and Jiangjiang Zhang

Biosensors 2025, 15(12), 804; https://doi.org/10.3390/bios15120804 - 8 Dec 2025

Abstract

Contemporary biomedical diagnostics increasingly demand high sensitivity for pathogen detection and real-time health monitoring. In response to these requirements, screen-printed electrochemical sensors (SPEs) have emerged as a practical analytical platform owing to their low cost, portability, and compatibility with point-of-care and wearable systems. [...] Read more.

Contemporary biomedical diagnostics increasingly demand high sensitivity for pathogen detection and real-time health monitoring. In response to these requirements, screen-printed electrochemical sensors (SPEs) have emerged as a practical analytical platform owing to their low cost, portability, and compatibility with point-of-care and wearable systems. In the recent past, nanomaterials in two-dimensional format, especially MXenes, have gained much interest due to their high electrical conductivity, controllable surface chemistry, and biocompatibility, which can improve the performance and applicability of SPEs. The current review concentrates on the latest developments between 2020 and 2025, providing a critical assessment of research employing MXene-based nanomaterials for the modification and development of screen-printed electrode platforms. We provide an overview of fabrication techniques, printing methods, and surface modification methods, and proceed with an analysis of the electrochemical performance of MXenes and MXene-based heterostructures. Lastly, contemporary issues are considered, and opinions are suggested to facilitate the translation of MXene-functionalized SPEs to real biomedical diagnosis solutions. Full article

(This article belongs to the Special Issue Point-of-Care Testing Using Biochemical Sensors for Health and Safety)

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13 pages, 3528 KB

Open AccessArticle

Urinary Metabolomic Changes and Potential Exercise-Induced Muscle Damage Biomarkers Identification in Trained Young Males Following Acute Intermittent Rowing Training

by Yang Cheng, Yue Yi, Xuefeng Shi and Shumin Bo

Biosensors 2025, 15(12), 803; https://doi.org/10.3390/bios15120803 - 8 Dec 2025

Abstract

(1) Background: This study aims to explore the changes in urinary metabolomic profile among trained young males following acute intermittent rowing training (AIRT), and to identify potential urinary biomarkers associated with exercise-induced muscle damage (EIMD). (2) Methods: 22 trained young males were recruited [...] Read more.

(1) Background: This study aims to explore the changes in urinary metabolomic profile among trained young males following acute intermittent rowing training (AIRT), and to identify potential urinary biomarkers associated with exercise-induced muscle damage (EIMD). (2) Methods: 22 trained young males were recruited to perform AIRT. The changes in blood biochemical indexes associated with EIMD were analyzed. EIMD occurrence was evaluated using blood biochemical indexes, muscle function, and pain assessment. The changes in urinary metabolites were determined using untargeted metabolomic analysis. (3) Results: Four blood biochemical indices, including creatine kinase, lactate dehydrogenase, creatine kinase-MB, and hydroxybutyrate dehydrogenase, were significantly elevated immediately after AIRT. Furthermore, an obvious immune response appeared, and countermovement jump performance significantly decreased. Among 384 urinary metabolites, 33 were significantly upregulated, and 12 were downregulated immediately after AIRT. Upregulated metabolites were mainly involved in phenylacetate metabolism, ammonia recycling, the urea cycle, and glutathione metabolism. Four potential urinary biomarkers were identified, including 2′-Deoxycytidine, cytosine, Phenylacetaldehyde, and Pyridoxamine. (4) Conclusions: AIRT induced EIMD in all participants and significantly altered urinary metabolite profiles. The changes in urinary metabolites and pathways were due to the metabolic adaptation to oxidative stress, inflammatory responses, and ammonia metabolism imbalance. The selected four potential urinary biomarkers provide important evidence for the further development of a non-invasive, urine-based method for the immediate assessment of EIMD. Full article

(This article belongs to the Special Issue Point-of-Care Testing Using Biochemical Sensors for Health and Safety)

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13 pages, 708 KB

Open AccessArticle

An Improved Dengue Virus Serotype-Specific Non-Structural Protein 1 Capture Immunochromatography Method with Reduced Sample Volume

by Warisara Sretapunya, Thitiya Buranachat, Montita Prasomthong, Rittichai Tantikorn, Areerat Sa-ngarsang, Sirirat Naemkhunthot, Laddawan Meephaendee, Pattara Wongjaroen, Chika Tanaka, Yoriko Shimadzu, Katsuya Ogata, Kunihiro Kaihatsu, Ryo Morita, Michinori Shirano, Juthamas Phadungsombat, Tadahiro Sasaki, Ritsuko Kubota-Koketsu, Yoshihiro Samune, Emi E. Nakayama and Tatsuo Shioda

Biosensors 2025, 15(12), 802; https://doi.org/10.3390/bios15120802 - 7 Dec 2025

Abstract

The four serotypes of dengue virus (DENV), types 1 to 4 (DENV-1 to DENV-4), exhibit approximately 60% identity in the encoded amino acid residues of viral proteins. Reverse transcription of RNA extracted from patient serum specimens followed by PCR amplification with serotype-specific probes [...] Read more.

The four serotypes of dengue virus (DENV), types 1 to 4 (DENV-1 to DENV-4), exhibit approximately 60% identity in the encoded amino acid residues of viral proteins. Reverse transcription of RNA extracted from patient serum specimens followed by PCR amplification with serotype-specific probes is the current standard technique for DENV serotyping. However, this method is time- and cost-consuming, and rapid detection systems with low cost are desirable. Previously, we developed a prototype serotype-specific immunochromatography system. That system was composed of four strips with four corresponding distinct sample buffers, each specifically detecting a single DENV serotype. In the present study, we improved this system by combining pairs of strips into one lateral-flow cassette each, providing DENV-1 and DENV-2 detection in one device and DENV-3 and DENV-4 detection in a second device; this strategy successfully reduced the required sample volume. Furthermore, we were able to adjust the composition of the sample buffers such that a single sample buffer sufficed for all four DENV serotype detection reactions, allowing much easier handling of the devices. Evaluation of this new device against laboratory and clinical DENV isolates and clinical specimens from DENV-infected individuals showed sensitivity that was comparable to that of our previous version, yielding serotype specificity of 100%. These new devices are expected to be of use in the clinical setting, accelerating both prospective and retrospective epidemiological studies. Full article

(This article belongs to the Special Issue Biosensors for Healthcare and Environment: Current and Future Perspectives)

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16 pages, 3740 KB

Open AccessArticle

The Role of Surfactants in Stabilizing Fluorescence Anisotropy for Protein–Aptamer Binding Affinity Measurements

by Bhagya R. Samarakoon, Susan L. Bilderback and Rebecca J. Whelan

Biosensors 2025, 15(12), 801; https://doi.org/10.3390/bios15120801 - 6 Dec 2025

Abstract

Fluorescence Anisotropy (FA) is a sensitive and efficient technique for quantifying biomolecular interactions, offering advantages such as minimal sample requirements and elimination of separation of bound from unbound species. Thus, it is well suited for aptamer–protein binding affinity studies. However, accurately determining equilibrium [...] Read more.

Fluorescence Anisotropy (FA) is a sensitive and efficient technique for quantifying biomolecular interactions, offering advantages such as minimal sample requirements and elimination of separation of bound from unbound species. Thus, it is well suited for aptamer–protein binding affinity studies. However, accurately determining equilibrium dissociation constants (K_D) in FA requires low concentrations of fluorescently labeled aptamers to prevent ligand depletion. A significant challenge arises at low aptamer concentrations due to an unexpected and physically nonmeaningful increase in apparent anisotropy, which impairs accurate data fitting. This anomalous increase in apparent anisotropy may arise from non-specific adsorption of aptamers to surfaces. In this study, we investigated the use of non-ionic surfactants to mitigate these effects and stabilize the anisotropy signal at low aptamer concentrations using the thrombin aptamer as a model system. We evaluated the impact of varying concentrations of two surfactants (Tween 20 and Triton X-100) on plots of anisotropy as a function of aptamer concentration and determined aptamer–protein binding affinities. Addition of 0.1% Tween 20 corrects the anomalous increase in anisotropy at low aptamer concentrations, enabling the use of aptamer concentrations as low as 5 nM in binding assays. Triton X-100 was less effective. By incorporating optimized concentrations of Tween 20, we demonstrated improved assay reproducibility and accuracy in K_D determination, expanding the dynamic range of usable aptamer concentrations in FA-based binding affinity studies. Similar benefits were observed with the clinically relevant aptamer s10yh2 and human serum albumin. These findings provide a practical strategy for enhancing the robustness of FA measurements and may be applicable to other aptamer–target systems and high-throughput assay formats. Full article

(This article belongs to the Special Issue Aptamer-Based Sensing: Designs and Applications)

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14 pages, 3378 KB

Open AccessArticle

Features of Chaperone Induction by 9-Aminoacridine and Acridine Orange

by Vadim V. Fomin, Svetlana V. Smirnova, Sergey V. Bazhenov, Aminat G. Kurkieva, Nikolay A. Bondarev, Daria M. Egorenkova, Daniil I. Sakharov, Ilya V. Manukhov and Serikbai K. Abilev

Biosensors 2025, 15(12), 800; https://doi.org/10.3390/bios15120800 - 6 Dec 2025

Abstract

The fluorescent dyes 9-aminoacridine (9-AA) and acridine orange (AO) are known mutagens that induce frameshift mutations in cells by intercalating between DNA bases. However, these chemicals can also affect other cellular components, such as proteins. In this study, we tested the ability of [...] Read more.

The fluorescent dyes 9-aminoacridine (9-AA) and acridine orange (AO) are known mutagens that induce frameshift mutations in cells by intercalating between DNA bases. However, these chemicals can also affect other cellular components, such as proteins. In this study, we tested the ability of 9-AA and AO to induce heat shock in bacteria using the following methods: lux-biosensors based on Escherichia coli cells with the luxCDABE genes transcriptionally fused to heat shock-specific inducible promoters, RT-qPCR, and nanoDSF. We demonstrated that acridine dyes not only induce mutagenesis but also cause heat shock in bacterial cells. AO significantly reduced the melting temperature of proteins and strongly activated σ^E- and σ³²-dependent promoters, but not PluxC, which is activated by elevated temperatures via a different mechanism. In contrast, 9-AA weakly denatured the proteins and induced the σ^E-dependent promoter; however, it activated the σ³²-dependent promoters and PluxC, supporting the hypothesis that the σ³² heat shock response system is activated via hairpin RNA denaturation by 9-AA. The study on the application of lux-biosensors was hampered by the high general toxicity and luminescence shielding effect of AO, and RT-qPCR’s sensitivity was insufficient for detection of the response to 9-AA. Thus, methodologically, it is justified to conduct a comprehensive study of substances that cause heat shock or affect bioluminescence by both RT-qPCR and lux-biosensors. Full article

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

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34 pages, 3756 KB

Open AccessReview

Smart Nucleic Acid Hydrogel-Based Biosensors: From Molecular Recognition and Responsive Mechanisms to Applications

by Lu Xu, Longjiao Zhu, Xiaoyu Wang, Wenqiang Zhang, Xiaoyun He, Yangzi Zhang and Wentao Xu

Biosensors 2025, 15(12), 799; https://doi.org/10.3390/bios15120799 - 5 Dec 2025

Abstract

Smart nucleic acid hydrogels (SNAHs), endowed with stimulus responsiveness, function as programmable molecular switches that can perceive diverse external stimuli and undergo rapid, reversible, and highly specific conformational or performance changes. These dynamic properties have enabled the rational design of biosensors with bionic [...] Read more.

Smart nucleic acid hydrogels (SNAHs), endowed with stimulus responsiveness, function as programmable molecular switches that can perceive diverse external stimuli and undergo rapid, reversible, and highly specific conformational or performance changes. These dynamic properties have enabled the rational design of biosensors with bionic behaviors, facilitating cascaded “recognition–decision–execution” processes that support advanced biological analysis. Consequently, SNAHs are recognized as a core breakthrough for the next generation of intelligent biosensing units. However, a systematic mapping between SNAH design strategies, specific stimuli, and application fields remains lacking. This review mainly analyzes advances in SNAH-based biosensors over the past five years, proposing flexible and feasible design strategies and key trends in customization. Firstly, we systematically summarize molecular recognition modules involved in the construction of SNAHs, including aptamers, DNAzymes, antibodies, and specific binding peptides. Subsequently, we elaborate on the responses of these modules to external stimuli, so as to further facilitate the signal transduction of signals derived from physical, chemical, and biological sources involving temperature, light, magnetic fields, pH, nucleic acids, proteins, other biomolecules, and pathogens. Additionally, the review outlines the research progress of SNAHs in environmental monitoring, food safety, and medical diagnostics. Finally, we provide an integrated perspective on future opportunities and challenges, highlighting the innovative framework for designing SNAH-based biosensors and offering a practical roadmap for next-generation intelligent sensing applications. Full article

(This article belongs to the Special Issue Polymers-Based Biosensors and Bioelectronics: Designs and Applications)

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21 pages, 3571 KB

Open AccessArticle

Machine Learning-Based Toothbrushing Region Recognition Using Smart Toothbrush Holder and Wearable Sensors

by Hsuan-Chih Wang, Ju-Hsuan Li, Yen-Chen Lin, Che-Yu Lin, Chien-Pin Liu, Tzu-Han Lin, Chia-Tai Chan and Chia-Yeh Hsieh

Biosensors 2025, 15(12), 798; https://doi.org/10.3390/bios15120798 - 5 Dec 2025

Abstract

Oral health is a critical factor in maintaining overall health, and its association with systemic diseases, including cardiovascular disease and diabetes mellitus, has been extensively investigated. Effective plaque removal through proper toothbrushing techniques is fundamental for preventing dental caries and periodontal diseases. Despite [...] Read more.

Oral health is a critical factor in maintaining overall health, and its association with systemic diseases, including cardiovascular disease and diabetes mellitus, has been extensively investigated. Effective plaque removal through proper toothbrushing techniques is fundamental for preventing dental caries and periodontal diseases. Despite standardized guidelines, many individuals fail to adhere to correct brushing techniques, thereby increasing the risk of oral diseases. To address this issue, this study proposes a fine-grained toothbrushing region recognition approach incorporating six machine learning classifiers and two inertial measurement units (IMUs), which are embedded in the toothbrush holder and mounted on the right wrist of the participant, respectively. By analyzing the continuous motion signals, the proposed hierarchical approach is capable of identifying brushing and transition activities and subsequently recognizing specific toothbrushing regions based on the predicted brushing activities. To further improve recognition reliability, post-processing strategies such as contextual smoothing and majority voting are applied. Experimental results demonstrate that random forest achieves the highest recognition accuracy of 96.13%, sensitivity of 96.10%, precision of 95.51%, and F1-score of 95.60%. The results indicate that the proposed approach is both effective and feasible for providing fine-grained toothbrushing region recognition in toothbrushing monitoring. Full article

(This article belongs to the Special Issue Wearable Biosensors and Health Monitoring)

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26 pages, 2770 KB

Open AccessArticle

Cellular Distribution and Motion of Essential Magnetosome Proteins Expressed in Mammalian Cells

by Qin Sun, Cécile Fradin, Moeiz Ahmed, R. Terry Thompson, Frank S. Prato and Donna E. Goldhawk

Biosensors 2025, 15(12), 797; https://doi.org/10.3390/bios15120797 - 4 Dec 2025

Abstract

Magnetosomes are organelle-like structures within magnetotactic bacteria that store iron biominerals in membrane-bound vesicles. In bacteria, formation of these structures is highly regulated by approximately 30 genes, which are conserved throughout different species. To compartmentalize iron in mammalian cells and provide gene-based contrast [...] Read more.

Magnetosomes are organelle-like structures within magnetotactic bacteria that store iron biominerals in membrane-bound vesicles. In bacteria, formation of these structures is highly regulated by approximately 30 genes, which are conserved throughout different species. To compartmentalize iron in mammalian cells and provide gene-based contrast for magnetic resonance imaging, we introduced key magnetosome proteins. The expression of essential magnetosome genes mamI and mamL as fluorescent fusion proteins in a human melanoma cell line confirmed their co-localization and interaction. Here, we investigate the expression of two more essential magnetosome genes, mamB and mamE, using confocal microscopy to describe fluorescent fusion protein expression patterns and analyze the observed intracellular mobility. Custom software was developed to characterize fluorescent particle trajectories. In mammalian cells, essential magnetosome proteins display different diffusive behaviours. However, all magnetosome proteins travelled at similar velocities when interacting with mammalian mobile elements, suggesting that MamL, MamL + MamI, MamB, and MamE interact with similar molecular motor proteins. These results confirm that localization and interaction of essential magnetosome proteins are feasible within the mammalian intracellular compartment. Full article

(This article belongs to the Special Issue Fluorescent Probes: Design and Biological Applications)

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34 pages, 1737 KB

Open AccessReview

Digging into the Solubility Factor in Cancer Diagnosis: A Case of Soluble CD44 Protein

by Zhuldyz Myrkhiyeva, Marzhan Nurlankyzy, Kulzhan Berikkhanova, Zhanas Baimagambet, Aidana Bissen, Nurzhan Bikhanov, Christabel K. L. Tan, Daniele Tosi, Zhannat Ashikbayeva and Aliya Bekmurzayeva

Biosensors 2025, 15(12), 796; https://doi.org/10.3390/bios15120796 - 4 Dec 2025

Abstract

The detection of soluble proteins in biological fluids, as a form of liquid biopsy, is a promising tool for cancer diagnosis and prognosis, as it is less invasive than traditional diagnostic methods. CD44 is one of the most recognized markers of cancer stem [...] Read more.

The detection of soluble proteins in biological fluids, as a form of liquid biopsy, is a promising tool for cancer diagnosis and prognosis, as it is less invasive than traditional diagnostic methods. CD44 is one of the most recognized markers of cancer stem cells, a small subset of cells responsible for cancer initiation, progression, and metastasis. Given the importance of CD44 as a cancer biomarker, several review articles explore the diagnostic and therapeutic value of cell-surface CD44. In addition to being a membrane-anchored protein, CD44 is also shed from the cell surface and can be found in various biological fluids. However, the role of soluble CD44 in cancer has not been comprehensively discussed in recent reviews. Measuring soluble CD44 in various biological liquids can provide a practical and valuable tool for cancer diagnosis and treatment monitoring. Therefore, this review comprehensively discusses the role of soluble CD44 as a marker in various cancer types, including serum, saliva, urine, and other fluids. In particular, its role as an early cancer biomarker and as a predictive and prognostic biomarker in several cancers is discussed. This work also provides an overview of a wide range of analytical techniques used to detect soluble CD44. The value of cells expressing CD44 versus soluble CD44 as a biomarker is also compared. The review concludes with a perspective on future directions, emphasizing the shift toward non-invasive analytical methods and the need for standardization of detection, including multiple biomarkers during evaluation, to improve the accuracy of cancer diagnosis. Full article

(This article belongs to the Section Biosensors and Healthcare)

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15 pages, 2464 KB

Open AccessArticle

A Novel Approach for Tissue Analysis in Joint Infections Using the Scattered Light Integrating Collector (SLIC)

by Elio Assaf, Cosmea F. Amerschläger, Vincent B. Nessler, Kani Ali, Robert Ossendorff, Max Jaenisch, Andreas C. Strauss, Christof Burger, Gunnar T. Hischebeth, Phillip J. Walmsley, Dieter C. Wirtz, Robert J. H. Hammond, Damien Bertheloot and Frank A. Schildberg

Biosensors 2025, 15(12), 795; https://doi.org/10.3390/bios15120795 - 4 Dec 2025

Abstract

Total joint arthroplasty is among the most common surgical procedures performed worldwide, with frequency increasing due to demographic changes. Accelerating the diagnostic process using new techniques is crucial for effective therapy. This pilot study aims to test such innovative technology in the context [...] Read more.

Total joint arthroplasty is among the most common surgical procedures performed worldwide, with frequency increasing due to demographic changes. Accelerating the diagnostic process using new techniques is crucial for effective therapy. This pilot study aims to test such innovative technology in the context of periprosthetic joint infection (PJI) using Scattered Light Integrating Collector (SLIC) technology. While we wish to evaluate whether SLIC can be used to reliably detect the status of infection within human tissue samples in the future, our current research focused on building its foundation by evaluating steps of sample preparation that allow for heightened growth depiction. It is, to our knowledge, the first study concerning the usage of solid human tissue samples using the SLIC device. Adult patients presenting with native or periprosthetic joint infections were included in this prospective study. Biopsies were obtained using sequential sampling, and bacterial density was optimized through titration series. Cryopreservation and agents influencing coagulation were investigated. Our study demonstrates that simple pretreatment could aid in detecting pathogen growth in infected tissue samples. Findings showed a clear advantage for no addition of agents affecting coagulation. Additionally, our protocols proved reliable after prolonged cryopreservation at −20 °C for up to 8 weeks, showing no significant difference compared to primary testing. AUC comparison showed comparable results for sample storage at −80 °C for up to 8 weeks. Similar outcomes were seen for samples ranging from 25 µL to 300 µL, with biological replicates displaying higher thresholds for larger volumes without significant differences. This study introduces a simple and quick diagnostic tool for detecting bacterial growth using tissue biopsies and develops an SOP for further research with this innovative technique. The suggested SOP enables SLIC to hint at an underlying bacterial infection within 5 h using joint tissue, offering a possible novel approach in diagnosing periprosthetic joint infections and septic arthritis. While not yet designed to compare sensitivity to other culture methods, it provides a solid basis for further clinical research. Full article

(This article belongs to the Special Issue Sensors for Detection of Bacteria and Their Toxins)

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35 pages, 3387 KB

Open AccessReview

Immunosensing Platforms for Detection of Metabolic Biomarkers in Oral Fluids

by Nadezhda S. Komova, Kseniya V. Serebrennikova, Anatoly V. Zherdev and Boris B. Dzantiev

Biosensors 2025, 15(12), 794; https://doi.org/10.3390/bios15120794 - 2 Dec 2025

Abstract

Widespread and simple detection of diseases and disfunctions in the body is crucial for reliable and prompt diagnostics, efficient use of healthcare resources, and improved quality of life. The presence of a large number of metabolic products in saliva, the relationship between their [...] Read more.

Widespread and simple detection of diseases and disfunctions in the body is crucial for reliable and prompt diagnostics, efficient use of healthcare resources, and improved quality of life. The presence of a large number of metabolic products in saliva, the relationship between their levels in saliva and blood, the diagnostic value of many of these compounds, and the advantages of noninvasive sampling drive interest in oral fluid as a biomatrix. This review summarizes established oral fluid biomarkers, as well as potential salivary indicators for remote health monitoring and noninvasive point-of-care diagnostics. Recent advances in the search for new solutions for sensitive and high-throughput immunodetection of biomarkers in oral fluid are discussed, along with strategies for overcoming the analytical and technical challenges associated with the salivary matrix testing. Another focus of the current review is optical and electrochemical immunosensors with an emphasis on lateral flow immunoassays for point-of-care testing due to their speed, simplicity and cost-effectiveness. Finally, future directions are discussed that may enable non-invasive monitoring of endocrine, infectious, immune, neurodegenerative diseases and other human conditions using immunoassay platforms, paving the way for personalized and accessible healthcare. Full article

(This article belongs to the Special Issue Biosensing Technologies in Medical Diagnosis—2nd Edition)

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36 pages, 6926 KB

Open AccessReview

AI-Integrated Micro/Nanorobots for Biomedical Applications: Recent Advances in Design, Fabrication, and Functions

by Prashant Kishor Sharma and Chia-Yuan Chen

Biosensors 2025, 15(12), 793; https://doi.org/10.3390/bios15120793 - 2 Dec 2025

Abstract

The integration of artificial intelligence (AI) and micro/nanorobotics is fundamentally reshaping biosensing by enabling autonomous, adaptive, and high-resolution biological analysis. These miniaturized robotic systems fabricated using advanced techniques such as photolithography, soft lithography, nanoimprinting, 3D printing, and self-assembly can navigate complex biological environments [...] Read more.

The integration of artificial intelligence (AI) and micro/nanorobotics is fundamentally reshaping biosensing by enabling autonomous, adaptive, and high-resolution biological analysis. These miniaturized robotic systems fabricated using advanced techniques such as photolithography, soft lithography, nanoimprinting, 3D printing, and self-assembly can navigate complex biological environments to perform targeted sensing, diagnostics, and therapeutic delivery. AI-driven algorithms, mainly those in machine learning (ML) and deep learning (DL), act as the brains of the operation, allowing for sophisticated modeling, genuine real-time control, and complex signal interpretation. This review focuses recent advances in the design, fabrication, and functional integration of AI-enabled micro/nanorobots for biomedical sensing. Applications that demonstrate their potential range from quick point-of-care diagnostics and in vivo biosensing to next-generation organ-on-chip systems and truly personalized medicine. We also discuss key challenges in scalability, energy autonomy, data standardization, and closed-loop control. Collectively, these advancements are paving the way for intelligent, responsive, and clinically transformative biosensing systems. Full article

(This article belongs to the Section Biosensors and Healthcare)

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18 pages, 1698 KB

Open AccessReview

Opportunities and Challenges in Gas Sensor Technologies for Accurate Detection of COVID-19

by Masoom Fatima, Munazza Fatima, Naseem Abbas and Pil-Gu Park

Biosensors 2025, 15(12), 792; https://doi.org/10.3390/bios15120792 - 2 Dec 2025

Abstract

Gas sensors provide versatile opportunities for detecting volatile organic compounds (VOCs) such as acetone, methanol, ethanol, propanol, isoprene, and aldehydes in exhaled breath (EB) associated with COVID-19 respiratory infections. These VOCs provide valuable information about metabolic markers linked with COVID-19. They have opened [...] Read more.

Gas sensors provide versatile opportunities for detecting volatile organic compounds (VOCs) such as acetone, methanol, ethanol, propanol, isoprene, and aldehydes in exhaled breath (EB) associated with COVID-19 respiratory infections. These VOCs provide valuable information about metabolic markers linked with COVID-19. They have opened opportunities to develop sensors for COVID-19 screening based on breath analysis. These sensors have the potential to provide the rapid detection of viruses in healthcare settings. RT-PCR, as a conventionally adopted diagnostic method, has a detection limit around 10–100 RNA copies/mL, with an accuracy of around 95%. Gas sensors have demonstrated VOC detection limits at the ppm level in COVID-19 EB and have displayed a sensitivity and specificity of 98.2% and 74.3%, respectively. Multiple gas sensors combined with machine learning algorithms have the potential to enhance the specificity of VOC detection. In addition to having an accuracy similar to that of the PCR method, the VOC-based diagnosis of COVID-19 offers unique advantages in terms of non-invasive and rapid detection. This review provides an overview of state-of-the-art gas sensors developed for COVID-19 detection. Despite there being significant developments in this field, there are certain challenges that still need to be addressed—these include the impact of environmental factors, the specificity of detection, the sensing range, and precision limitations, leading to accuracy issues. Despite these existing challenges, the integration of gas sensors with machine learning methods can enhance the accuracy of the detection of COVID-19. Future research directions are proposed to validate and standardize the application of gas sensors for COVID-19 in clinical settings. Full article

(This article belongs to the Special Issue Sensors for Detection of Virus and Bacteria)

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12 pages, 2207 KB

Open AccessArticle

Rapid Detection of Staphylococcus aureus from Gym Environments for Health Risk Monitoring Using Printed Nanochains-Based Biosensors

by Liang Huang, Shidong Hu, Zhicheng Zheng, Yaxin Li, Maolin Xu, Zeying Zhang, Jingqun Cheng, Yujing Zhang, Yonggan Xue, Meng Su and Xiaohui Du

Biosensors 2025, 15(12), 791; https://doi.org/10.3390/bios15120791 - 1 Dec 2025

Abstract

Gyms are indoor environments in which many people perform physical exercise and could potentially increase the risks of bacterial contamination and dissemination. Staphylococcus aureus (S. aureus) is one of the most prevalent bacteria in community-acquired infections; thus, the rapid detection and [...] Read more.

Gyms are indoor environments in which many people perform physical exercise and could potentially increase the risks of bacterial contamination and dissemination. Staphylococcus aureus (S. aureus) is one of the most prevalent bacteria in community-acquired infections; thus, the rapid detection and continuous monitoring of S. aureus are crucial for evaluating the hygienic status of gym environments. This work describes the fabrication of a nanochain-based biosensor for S. aureus detection using carboxyl-modified polystyrene (PS) nanoparticles functionalized with a specific antibody. When target bacteria bind to the nanochains, they yield distinct color changes which support the directly visualizable analysis of optical images, recorded using optical microscopy or even a smart mobile phone. In addition to high portability, this biosensor is also capable of the quantification and continuous monitoring of the bacterial load in a gym environment over a broad linear range (10⁰ CFU/mL~10⁵ CFU/mL), with a detection limit of 1 CFU/mL. In summary, this study validated the applicability of the biosensors for the rapid detection and real-time monitoring of gym environmental pathogens. Full article

(This article belongs to the Section Biosensor and Bioelectronic Devices)

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16 pages, 4816 KB

Open AccessArticle

Deep Learning-Assisted Cactus-Inspired Osmosis-Enrichment Patch for Biosafety-Isolative Wearable Sweat Metabolism Assessment

by Yuwen Yan, Ting Xiao, Miaorong Lin, Wenyan Yue, Jihan Qu, Yonghuan Chen, Zhihao Zhang, Jianxin Meng, Dong Pan, Fengyu Li and Bingtian Su

Biosensors 2025, 15(12), 790; https://doi.org/10.3390/bios15120790 - 1 Dec 2025

Abstract

Sweat, which contains a rich array of biomarkers, serves as a vital biological fluid for non-invasive biosensing. Wearable sweat sensors have garnered significant interest owing to their portability and capacity for continuous monitoring. However, there are safety concerns regarding the direct contact of [...] Read more.

Sweat, which contains a rich array of biomarkers, serves as a vital biological fluid for non-invasive biosensing. Wearable sweat sensors have garnered significant interest owing to their portability and capacity for continuous monitoring. However, there are safety concerns regarding the direct contact of sweat sensors with the skin during the detection process. The chemical substances in the sensor patches may cause contamination of the epidermis when in contact with the skin, leading to skin allergic reactions. Sample collection and biosafety isolation are critical issues in wearable sweat detection. To address this, we develop a cactus-inspired biomimetic Janus membrane capable of unidirectionally transporting and concentrating sweat toward a designated detection zone. Through unidirectional transport from the hydrophobic layer to the hydrophilic layer of the Janus membrane, sweat droplets are enriched at the designated detection point of the conical hydrophilic pattern via Laplace pressure. The bionic osmosis-enrichment sensing patch effectively inhibits direct contact between indicators and skin, eliminating potential epidermal contamination. This achieved the effect of in situ perspiration collection under the premise of biosafety isolation. To rapidly and accurately analyze sweat biomarkers, we employ a deep learning (DL)-assisted fluorescence sensor for efficient and precise detection of biomarker concentrations. A dataset of 4500 fluorescence images are constructed and used to evaluate two DL and seven machine learning (ML) algorithms. The convolutional neural network (CNN) model could easily and accurately classify and quantitatively analyze the total concentration of the amino acid mixture, Ca²⁺ and Cl⁻, with 100% classification accuracy. The consistency between the detection results of actual sweat by the DL-assisted fluorescence method and fluorescence spectroscopy was 91.4–96.0%. This approach demonstrates high reliability in sweat collection and analysis, offering a practical tool for clinical health monitoring, early disease intervention, and diagnosis. Full article

(This article belongs to the Section Biosensor and Bioelectronic Devices)

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34 pages, 4925 KB

Open AccessReview

Nanomaterial Engineered Biosensors and Stimulus–Responsive Platform for Emergency Monitoring and Intelligent Diagnosis

by Bo Fang, Yuanyuan Chen, Hui Jiang, Xiaohui Liu and Xuemei Wang

Biosensors 2025, 15(12), 789; https://doi.org/10.3390/bios15120789 - 1 Dec 2025

Abstract

Biosensing technology serves as a cornerstone in biomedical diagnostics, environmental monitoring, personalized medicine, and wearable devices, playing an indispensable role in precise detection and real–time monitoring. Compared with traditional sensing platforms, functional nanomaterials—by virtue of their ultra–large specific surface area, exceptional optoelectronic properties, [...] Read more.

Biosensing technology serves as a cornerstone in biomedical diagnostics, environmental monitoring, personalized medicine, and wearable devices, playing an indispensable role in precise detection and real–time monitoring. Compared with traditional sensing platforms, functional nanomaterials—by virtue of their ultra–large specific surface area, exceptional optoelectronic properties, and superior catalytic activity—significantly enhance the sensitivity, selectivity, and response speed of biosensors. This has enabled ultrasensitive, rapid, and even in situ detection of disease biomarkers, pollutants, and pathogens. This review summarizes recent advances in five key categories of functional nanomaterials—metallic, semiconductor, carbon–based, two–dimensional, and stimulus–responsive materials—for advanced biosensing applications. It elucidates the structure–property relationships governing sensing performance, such as the surface plasmon resonance of gold nanoparticles and the high carrier mobility of graphene, and analyzes the core mechanisms behind optical sensing, electrochemical sensing, and emerging multimodal sensing strategies. With a focus on medical diagnostics, wearable health monitoring, and environmental and food safety surveillance, the review highlights the application value of functional nanomaterials across diverse scenarios. Current research is progressively moving beyond single–performance optimization toward intelligent design, multifunctional integration, and real–world deployment, though challenges related to industrial application remain. Finally, the review outlines existing issues in the development of functional nanomaterial–based biosensors and offers perspectives on the integration of nanomaterials with cutting–edge technologies and the construction of novel sensing systems. This work aims to provide insights for the rational design of functional nanomaterials and the cross–disciplinary translation of biosensing technologies. Full article

(This article belongs to the Special Issue Nanomaterial-Based Biosensors for Biomedical Detection)

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20 pages, 3539 KB

Open AccessArticle

Real-Time Monitoring of NIH/3T3 Cell Growth and Drug Reaction Using Impedance Biosensors and Comparison with Biological Assays

by Seok-kyu Kim, Gayoung Lee, Yeeun Kim, Dahyun Kang and Moongyu Jang

Biosensors 2025, 15(12), 788; https://doi.org/10.3390/bios15120788 - 1 Dec 2025

Abstract

Impedance biosensors are manufactured on glass slides using a semiconductor process to monitor cell growth and cell–drug reactions in real time, and the results are compared with biological assay results to confirm the validity of impedance measurement method. Approximately 10,000 cells per well [...] Read more.

Impedance biosensors are manufactured on glass slides using a semiconductor process to monitor cell growth and cell–drug reactions in real time, and the results are compared with biological assay results to confirm the validity of impedance measurement method. Approximately 10,000 cells per well were cultured for 48 h, after which 6.67 μg/mL puromycin was injected to observe apoptosis over the following 48 h. A frequency sweep from 1 kHz to 1 MHz was performed to determine the optimal frequency range, identifying 367–440 kHz as the most sensitive for detecting impedance changes. Impedance was measured every 10 min for 96 h. Capacitance gradually increased during cell proliferation, while after drug administration, a transient increase occurred within 9 h, followed by a rapid decline, indicating cell death within 24 h. The sensor utilized Electrical Cell–substrate Impedance Sensing (ECIS) to detect real-time changes in cell status without the need for staining or destruction. Comparison with conventional biological assays such as MTS and FACS confirmed that the impedance biosensor provided higher sensitivity and quantitative accuracy in monitoring both cell proliferation and apoptosis. This study demonstrates that the developed biosensor enables label-free, non-invasive, and continuous monitoring of cellular behaviors with acceptable coincidence with 3 different biological assay results. Impedance biosensor presents a promising alternative to conventional biological assays and offers potential applications in drug screening, cytotoxicity evaluation, and real-time biological monitoring. Full article

(This article belongs to the Special Issue Advanced Biosensors for Disease Screening, Monitoring, Diagnosis and Treatment)

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