Biosensors

19 pages, 6630 KiB

Open AccessArticle

Improving the Accuracy of a Wearable Uroflowmeter for Incontinence Monitoring Under Dynamic Conditions: Leveraging Machine Learning Methods

by Faezeh Shanehsazzadeh, John O. L. DeLancey and James A. Ashton-Miller

Biosensors 2025, 15(5), 306; https://doi.org/10.3390/bios15050306 (registering DOI) - 11 May 2025

Abstract

Urinary incontinence affects many women, yet there are no monitoring devices capable of accurately capturing flow dynamics during everyday activities. Building on our initial development of a wearable personal uroflowmeter, this study enhances the device’s performance under realistic, dynamic conditions similar to those [...] Read more.

Urinary incontinence affects many women, yet there are no monitoring devices capable of accurately capturing flow dynamics during everyday activities. Building on our initial development of a wearable personal uroflowmeter, this study enhances the device’s performance under realistic, dynamic conditions similar to those encountered in daily living. We integrated an optimized eight-vane Etoile flow conditioner with a 0.2D opening into the device. Both computational fluid dynamics simulations and experimental tests demonstrated that this flow conditioner significantly reduced turbulence intensity by 82% and stabilized the axial velocity profile by 67%, increasing the R² of flow rate measurements from 0.44 to 0.92. Furthermore, our machine learning framework—utilizing a support vector machine (SVM) and an extreme gradient boosting (XGBoost) model with principal component analysis (PCA)—accurately predicted the true flow rate with high correlations, robust performance, and minimal overfitting. For the test dataset, the SVM achieved a correlation of 0.86, an R² of 0.74, and an MAE of 2.8, whereas the XGBoost-PCA model exhibited slightly stronger performance, with a correlation of 0.88, an R² of 0.76, and an MAE of 2.6. These advances established a solid foundation for developing a reliable, wearable uroflowmeter capable of effectively monitoring urinary incontinence in real-world settings. Full article

(This article belongs to the Special Issue Advances in Flexible and Wearable Biosensors)

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21 pages, 1189 KiB

Open AccessArticle

Gait Phase Recognition in Multi-Task Scenarios Based on sEMG Signals

by Xin Shi, Xiaheng Zhang, Pengjie Qin, Liangwen Huang, Yaqin Zhu and Zixiang Yang

Biosensors 2025, 15(5), 305; https://doi.org/10.3390/bios15050305 (registering DOI) - 10 May 2025

Abstract

In the human–exoskeleton interaction process, accurately recognizing gait phases is crucial for effectively assessing the assistance provided by the exoskeleton. However, due to the similarity in muscle activation patterns between adjacent gait phases, the recognition accuracy is often low, which can easily lead [...] Read more.

In the human–exoskeleton interaction process, accurately recognizing gait phases is crucial for effectively assessing the assistance provided by the exoskeleton. However, due to the similarity in muscle activation patterns between adjacent gait phases, the recognition accuracy is often low, which can easily lead to confusion in surface electromyography (sEMG) feature extraction. This paper proposes a real-time recognition method based on multi-scale fuzzy approximate root mean entropy (MFAREn) and an Efficient Multi-Scale Attention Convolutional Neural Network (EMACNN), building upon the concept of fuzzy approximate entropy. MFAREn is used to extract the dynamic complexity and energy intensity features of sEMG signals, serving as the input matrix for EMACNN to achieve fast and accurate gait phase recognition. This study collected sEMG signals from 10 subjects performing continuous lower limb gait movements in five common motion scenarios for experimental validation. The results show that the proposed method achieves an average recognition accuracy of 95.72%, outperforming the other comparison methods. The method proposed in this paper is significantly different compared to other methods (p < 0.001). Notably, the recognition accuracy for walking in level walking, stairs ascending, and ramp ascending exceeds 95.5%. This method demonstrates a high recognition accuracy, enabling sEMG-based gait phase recognition and meeting the requirements for effective human–exoskeleton interaction. Full article

(This article belongs to the Section Wearable Biosensors)

16 pages, 1919 KiB

Open AccessArticle

Multi-Parametric Electrochemical Sensing Platform: Applications in Animal Welfare

by C. Ferreira, E. Lynch, A. O’Herlihy, F. Barry, L. C. Nagle, S. R. Teixeira and P. Galvin

Biosensors 2025, 15(5), 304; https://doi.org/10.3390/bios15050304 (registering DOI) - 10 May 2025

Abstract

The rapid growth of the dairy sector requires advanced monitoring tools to ensure sustainable practices that benefit the environment, economy, and human health. Current monitoring devices often lack multi-parametric capabilities, limiting their ability to provide comprehensive data on critical chemical and biochemical parameters. [...] Read more.

The rapid growth of the dairy sector requires advanced monitoring tools to ensure sustainable practices that benefit the environment, economy, and human health. Current monitoring devices often lack multi-parametric capabilities, limiting their ability to provide comprehensive data on critical chemical and biochemical parameters. To address this challenge, this work presented the integration of a real-time multi-parametric device with sensors for pH, temperature, nitrate, and nitrite, providing a comprehensive solution to dairy cattle health monitoring. This solution included an electrochemical platform, Portable Unit for Lab-on-Site Electrochemistry (PULSE), and an application for data processing and display. In-house fabricated flexible gold-printed electrodes demonstrated accurate detection of nitrite and nitrate when integrated with the PULSE, achieving sensitivities of 6.32

μ

A/ppm/

{cm}^{2}

in artificial interstitial fluid and 1.92

μ

A/ppm/

{cm}^{2}

in phosphate buffered saline, respectively. The PULSE achieved 65.83% and 58.3% lower limits of detection in phosphate buffered saline than a benchtop potentiostat, for nitrate and nitrite, respectively, along with a 24.5% increase in nitrite sensitivity, enhancing its ability to detect lower analyte concentrations. pH sensing was carried out with a commercial screen-printed electrode coated with a layer of iridium oxide. The pH was tested in ruminal complex fluid, obtaining a pH sensitivity of −59.63 mV/pH and an accuracy of 98.9%. These findings highlighted the potential of this technology as an effective tool for dairy cattle health monitoring and its deployment in real-world scenarios. Full article

(This article belongs to the Special Issue Novel Nanomaterials and Nanotechnology: From Fabrication Methods and Improvement Strategies to Applications in Biosensing and Biomedicine (2nd Edition))

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16 pages, 4093 KiB

Open AccessArticle

AFM-Based Monitoring of Enzymatic Activity of Individual Molecules of Cytochrome CYP102A1

by Yuri D. Ivanov, Natalia S. Bukharina, Ivan D. Shumov, Oleg N. Afonin, Vadim Y. Tatur, Anna V. Grudo and Alexander I. Archakov

Biosensors 2025, 15(5), 303; https://doi.org/10.3390/bios15050303 (registering DOI) - 10 May 2025

Abstract

Herein, we report the use of a nanotechnology-based approach for the study of enzyme-functionalized mica surfaces. Atomic force microscopy (AFM) has been employed for the determination of the catalytic activity of single molecules of heme-containing cytochrome P450 CYP102A1 (CYP102A1) enzyme, which was immobilized [...] Read more.

Herein, we report the use of a nanotechnology-based approach for the study of enzyme-functionalized mica surfaces. Atomic force microscopy (AFM) has been employed for the determination of the catalytic activity of single molecules of heme-containing cytochrome P450 CYP102A1 (CYP102A1) enzyme, which was immobilized on the surface of a mica chip. Height fluctuations in individual molecules of the enzyme were measured under near-native conditions by AFM measurements in liquid using a cantilever with a 10 to 20 nm tip curvature radius. We have found that in the process of enzymatic catalysis, the mean amplitude of height fluctuations in individual enzyme molecules is 1.4-fold higher than that of enzyme molecules in an inactive state. The temperature dependence of the mean amplitude of height fluctuations in cytochrome CYP102A1 has been revealed, and the maximum of this dependence has been observed at 22 °C. The proposed nanotechnology-based approach can be employed in studies of a wide variety of enzymes, which are important for the development of novel diagnostic tests and systems for pharmaceutical analysis. The approach developed in our work will favor further miniaturization of enzyme-based biosensors and the transition from traditional sensors to nanobiosensors. Full article

(This article belongs to the Special Issue Miniature Sensors Based on Highly Efficient Chemical and Biological Sensing Interfaces)

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11 pages, 2977 KiB

Open AccessArticle

An Electrochemical Aptasensor for Accurate and Sensitive Detection of Exosomes Based on Dual-Probe Recognition and Hybridization Chain Reaction

by Haojie Ma, Jie Li, Mengjia Gao, Yan Dong, Yi Luo and Shao Su

Biosensors 2025, 15(5), 302; https://doi.org/10.3390/bios15050302 - 9 May 2025

Abstract

The accurate and sensitive detection of tumor-derived exosomes holds significant promise for the early diagnosis of cancer. In this study, an electrochemical aptasensor was developed for the high-performance detection of exosomes by integrating dual-probe recognition and hybridization chain reaction (HCR). A dual-probe recognition [...] Read more.

The accurate and sensitive detection of tumor-derived exosomes holds significant promise for the early diagnosis of cancer. In this study, an electrochemical aptasensor was developed for the high-performance detection of exosomes by integrating dual-probe recognition and hybridization chain reaction (HCR). A dual-probe recognition unit composed of a MUC1 aptamer (MUC1-Apt) probe and cholesterol probe was designed for capturing target exosomes and reducing the interference from free proteins, significantly improving the accuracy of exosome detection. It should be noted that the dual-probe recognition unit was formed in conjunction with the HCR. Moreover, a large number of biotins were also assembled on the HCR product, which were used to capture avidin–horseradish peroxidase (SA-HRP) for signal amplification. The CD63 aptamer (CD63-Apt) was immobilized on the surface of a gold electrode for specifically capturing exosomes to construct a classical sandwiched structure. The loaded SA-HRP can efficiently catalyze the reaction of 3, 3′, 5, 5′ tetramethylbenzidine (TMB) and hydrogen peroxide (H₂O₂) to generate a large electrochemical signal. According to this phenomenon, a linear relationship of this proposed aptasensor was achieved between the electrochemical response and 1 × 10²–1 × 10⁷ particles/mL exosomes, with a detection limit of 45 particles/mL. Moreover, the aptasensor exhibited accepted stability and potential clinical applicability. All results proved that this aptasensor has a promising application in exosome-based disease diagnostics. Full article

(This article belongs to the Special Issue Electrochemical Biosensing Platforms for Food, Drug and Health Safety)

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13 pages, 5541 KiB

Open AccessArticle

Bridging Blood and Skin: Biomarker Profiling in Dermal Interstitial Fluid (dISF) for Minimally Invasive Diagnostics

by Yann Sprunger, Johan Longo, Ali Saeidi and Adrian M. Ionescu

Biosensors 2025, 15(5), 301; https://doi.org/10.3390/bios15050301 - 9 May 2025

Abstract

Understanding the biochemical relationship between serum and dermal interstitial fluid (dISF) is critical for advancing minimally invasive diagnostics with wearables and point of care devices focusing on most relevant biomarkers accessible in the ISF. This work compares the composition of dISF and serum [...] Read more.

Understanding the biochemical relationship between serum and dermal interstitial fluid (dISF) is critical for advancing minimally invasive diagnostics with wearables and point of care devices focusing on most relevant biomarkers accessible in the ISF. This work compares the composition of dISF and serum using Xsensio’s microneedle-based collector, which yields an average of 3.4

μ

L/h. In the first study, total protein content, human serum albumin (HSA), and immunoglobulin G (IgG) are quantified in twelve volunteers. A second study is dedicated to screening 50 inflammation-related protein biomarkers across twenty volunteers. The results demonstrate that dISF closely resembles serum in its major protein constituents but at reduced concentrations (e.g., 57% for total protein). Strong correlations are observed between dISF and serum for CRP and SAA (

R^{2} > 0.87

), primarily driven by a subject with pathological levels, demonstrating the ability of dISF to reflect systemic inflammation. This study originally reports NT-proBNP detection at comparable levels in both fluids, suggesting that dISF could serve as a reliable proxy for blood NT-proBNP in the non-invasive diagnosis of cardiac failure. Cytokine profiling reveals 36 detectable cytokines, including several unique to dISF. Notably, interleukin concentrations are found to be highly similar between the two fluids. These experimental findings support dISF as a promising diagnostic medium for monitoring both localized and systemic biomarkers in clinical applications. Full article

(This article belongs to the Special Issue Nano Biosensors and Their Applications for In Vivo/Vitro Diagnosis—2nd Edition)

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17 pages, 2642 KiB

Open AccessArticle

Optimizing Whole-Cell Biosensors for the Early Detection of Crop Infections: A Proof-of-Concept Study

by Nadav Zanger and Evgeni Eltzov

Biosensors 2025, 15(5), 300; https://doi.org/10.3390/bios15050300 - 8 May 2025

Abstract

This study presents a proof-of-concept evaluation of optimized whole-cell biosensors designed for the real-time detection of crop infections. Genetically engineered luminescent bacterial strains were used to detect volatile organic compounds (VOCs) emitted by crops during spoilage. Key factors investigated include bacterial uniformity, nutrient [...] Read more.

This study presents a proof-of-concept evaluation of optimized whole-cell biosensors designed for the real-time detection of crop infections. Genetically engineered luminescent bacterial strains were used to detect volatile organic compounds (VOCs) emitted by crops during spoilage. Key factors investigated include bacterial uniformity, nutrient supply, and temperature effects. The results demonstrated that lower temperatures (+4 °C) yielded higher sensor sensitivity and prolonged bacterial viability. A proof-of-concept evaluation was conducted in storage-like conditions, showing effective infection detection in potatoes. These findings underscore the potential of whole-cell-based biosensors for monitoring postharvest production in cold storage environments. Full article

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

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17 pages, 13507 KiB

Open AccessArticle

Molecular Association Assay Systems for Imaging Protein–Protein Interactions in Mammalian Cells

by Sung-Bae Kim, Tadaomi Furuta, Suresh Thangudu, Arutselvan Natarajan and Ramasamy Paulmurugan

Biosensors 2025, 15(5), 299; https://doi.org/10.3390/bios15050299 - 8 May 2025

Abstract

Molecular imaging probes play a pivotal role in assaying molecular events in various physiological systems. In this study, we demonstrate a new genre of bioluminescent probes for imaging protein–protein interactions (PPIs) in mammalian cells, named the molecular association assay (MAA) probe. The MAA [...] Read more.

Molecular imaging probes play a pivotal role in assaying molecular events in various physiological systems. In this study, we demonstrate a new genre of bioluminescent probes for imaging protein–protein interactions (PPIs) in mammalian cells, named the molecular association assay (MAA) probe. The MAA probe is designed to be as simple as a full-length marine luciferase fused to a protein of interest with a flexible linker. This simple fusion protein alone surprisingly works by recognizing a specific ligand, interacting with a counterpart protein of the PPI, and developing bioluminescence (BL) in mammalian cells. We made use of an artificial intelligence (AI) tool to simulate the binding modes and working mechanisms. Our AlphaFold-based analysis on the binding mode suggests that the hinge region of the MAA probe is flexible before ligand binding but becomes stiff after ligand binding and protein association. The sensorial properties of representative MAA probes, FRB-ALuc23 and FRB-R86SG, are characterized with respect to the quantitative feature, BL spectrum, and in vivo tumor imaging using xenografted mice. Our AI-based simulation of the working mechanisms reveals that the association of MAA probes with the other proteins works in a way to facilitate the substrate’s access to the active sites of the luciferase (ALuc23 or R86SG). We prove that the concept of MAA is generally applicable to other examples, such as the ALuc16- or R86SG-fused estrogen receptor ligand-binding domain (ER LBD). Considering the versatility of this conceptionally unique and distinctive molecular imaging probe compared to conventional ones, we are expecting the widespread application of these probes as a new imaging repertoire to determine PPIs in living organisms. Full article

(This article belongs to the Special Issue AI-Enabled Biosensor Technologies for Boosting Medical Applications)

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16 pages, 4866 KiB

Open AccessArticle

Centrifugation-Induced Stable Colloidal Silver Nanoparticle Aggregates for Reproducible Surface-Enhanced Raman Scattering Detection

by Tianyu Zhou and Zhiyang Zhang

Biosensors 2025, 15(5), 298; https://doi.org/10.3390/bios15050298 - 8 May 2025

Abstract

Colloidal noble metal nanoparticle aggregates have demonstrated significant advantages in surface-enhanced Raman scattering (SERS) analysis, particularly for online detection, due to their excellent optical properties, spatial homogeneity, and fluidic compatibility. However, conventional chemically induced aggregation methods (such as salt-induced nanoparticle aggregation) suffer from [...] Read more.

Colloidal noble metal nanoparticle aggregates have demonstrated significant advantages in surface-enhanced Raman scattering (SERS) analysis, particularly for online detection, due to their excellent optical properties, spatial homogeneity, and fluidic compatibility. However, conventional chemically induced aggregation methods (such as salt-induced nanoparticle aggregation) suffer from uncontrolled aggregation, limited stability, and narrow detection windows, which restrict their quantitative and long-term applications. In this study, we developed a non-chemical method for fabricating stable colloidal aggregates from uniform β-cyclodextrin-stabilized silver nanoparticles (β-CD@AgNPs) via centrifugation. By precisely controlling the addition rate of silver nitrate, we synthesized β-cyclodextrin-stabilized silver nanoparticles with a uniform size. Surprisingly, these nanoparticles can form highly dispersed and homogeneous colloidal aggregates simply via centrifugation, which is completely different from the behavior of traditional ligand-modified nanoparticles. Notably, the resulting aggregates exhibit excellent SERS enhancement, enabling the sensitive detection of various dyes at nanomolar levels. Furthermore, they maintain a stable SERS signal (RSD = 6.99%) over a detection window exceeding 1 h, markedly improving signal stability and reproducibility compared with salt-induced aggregates. Additionally, using pyocyanin as a model analyte, we evaluated the quantitative performance of these aggregates (LOD = 0.2 nM), achieving satisfactory recovery (82–117%) in spiked samples of drinking water, lake water, and tap water. This study provides a facile strategy for fabricating stable colloidal SERS substrates and paves the way for the advancement of SERS applications in analytical sciences. Full article

(This article belongs to the Special Issue Miniature Sensors Based on Highly Efficient Chemical and Biological Sensing Interfaces)

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45 pages, 8234 KiB

Open AccessReview

Review of Non-Invasive Imaging Technologies for Cutaneous Melanoma

by Luke Horton, Joseph W. Fakhoury, Rayyan Manwar, Ali Rajabi-Estarabadi, Dilara Turk, Sean O’Leary, Audrey Fotouhi, Steven Daveluy, Manu Jain, Keyvan Nouri, Darius Mehregan and Kamran Avanaki

Biosensors 2025, 15(5), 297; https://doi.org/10.3390/bios15050297 - 7 May 2025

Abstract

Imaging technologies are constantly being developed to improve not only melanoma diagnosis, but also staging, treatment planning, and disease progression. We start with a description of how melanoma is characterized using histology, and then continue by discussing nearly two dozen different technologies, including [...] Read more.

Imaging technologies are constantly being developed to improve not only melanoma diagnosis, but also staging, treatment planning, and disease progression. We start with a description of how melanoma is characterized using histology, and then continue by discussing nearly two dozen different technologies, including systems currently used in medical practice and those in development. For each technology, we describe its method of operation, how it is or would be projected to be most commonly used in diagnosing and managing melanoma, and for systems in current use, we identify at least one current manufacturer. We also provide a table including the biomarkers identified by and main limitations associated with each technology and conclude by offering suggestions on specific characteristics that might best enhance a technology’s potential for widespread clinical adoption. Full article

(This article belongs to the Special Issue Advanced Optical Methods for Biosensing)

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23 pages, 5249 KiB

Open AccessReview

Carbon Nanotube-Based Field-Effect Transistor Biosensors for Biomedical Applications: Decadal Developments and Advancements (2016–2025)

by Joydip Sengupta and Chaudhery Mustansar Hussain

Biosensors 2025, 15(5), 296; https://doi.org/10.3390/bios15050296 - 7 May 2025

Abstract

Advancements in carbon nanotube-based FET (CNT-FET) biosensors from 2016 to 2025 have boosted their sensitivity, specificity, and rapid detection performance for biomedical purposes. This review highlights key innovations in transducer materials, functionalization strategies, and device architectures, including floating-gate CNT-FETs for detecting cancer biomarkers, [...] Read more.

Advancements in carbon nanotube-based FET (CNT-FET) biosensors from 2016 to 2025 have boosted their sensitivity, specificity, and rapid detection performance for biomedical purposes. This review highlights key innovations in transducer materials, functionalization strategies, and device architectures, including floating-gate CNT-FETs for detecting cancer biomarkers, infectious disease antigens, and neurodegenerative disease markers. Novel approaches, such as dual-microfluidic field-effect biosensor (dual-MFB) structures and carboxylated graphene quantum dot (cGQD) coupling, have further expanded their diagnostic potential. Despite significant progress, challenges in scalability, reproducibility, and long-term stability remain. Overall, this work highlights the transformative potential of CNT-FET biosensors while outlining a roadmap for translating laboratory innovations into practical, high-impact biomedical applications. Full article

(This article belongs to the Special Issue Biosensors Based on Transistors)

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13 pages, 1045 KiB

Open AccessArticle

Rapid and Highly Sensitive Detection of Ricin in Biological Fluids Using Optical Modulation Biosensing

by Eliana Levy, Linoy Golani-Zaidie, Shmuel Burg, Efi Makdasi, Ron Alcalay, Reut Falach, Ofir Schuster and Amos Danielli

Biosensors 2025, 15(5), 295; https://doi.org/10.3390/bios15050295 - 6 May 2025

Abstract

Ricin, a highly toxic glycoprotein derived from the seeds of Ricinus communis, poses significant risks in bioterrorism and toxicology due to its rapid absorption and ease of dissemination. Rapid, ultra-sensitive detection is crucial for timely medical intervention and implementing security measures. However, existing [...] Read more.

Ricin, a highly toxic glycoprotein derived from the seeds of Ricinus communis, poses significant risks in bioterrorism and toxicology due to its rapid absorption and ease of dissemination. Rapid, ultra-sensitive detection is crucial for timely medical intervention and implementing security measures. However, existing methods often lack sufficient sensitivity or require lengthy processing, limiting their utility for trigger-to-treat scenarios. Here, we present an optical modulation biosensing (OMB)-based ricin assay capable of detecting low concentrations of ricin in buffer, plasma, and biological samples. The assay combines magnetic-bead-based target capture with fluorescent signal enhancement, achieving a limit of detection (LoD) of 15 pg/mL in buffer and 62 pg/mL in plasma, with a 4-log dynamic range. Optimized protocols reduced the assay time to 60 min, maintaining an LoD of 114 pg/mL in plasma while preserving accuracy and reproducibility. The assay successfully detected ricin in bronchoalveolar lavage fluid and serum from mice that were intranasally exposed to ricin, with signals persisting up to 48 h post exposure. Its rapid, high-throughput capabilities and simplified workflow make the OMB-based assay a powerful tool for toxicology, forensic analysis, and counter-bioterrorism. This study highlights the OMB platform’s potential as a sensitive and robust diagnostic tool for detecting hazardous biological agents. Full article

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

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18 pages, 1686 KiB

Open AccessArticle

An Extracellular Vesicle (EV) Paper Strip for Rapid and Convenient Estimation of EV Concentration

by Gisela Ströhle, Rebecca Goodrum and Huiyan Li

Biosensors 2025, 15(5), 294; https://doi.org/10.3390/bios15050294 - 6 May 2025

Abstract

Extracellular vesicles (EVs) have emerged as promising biomarkers and therapeutic agents, yet their quantification remains technically challenging due to the limitations of conventional methods. Here, a low-cost, fluorescence-based, paper-strip immunoassay is presented for rapid and semi-quantitative estimation of EV concentration, inspired by pH [...] Read more.

Extracellular vesicles (EVs) have emerged as promising biomarkers and therapeutic agents, yet their quantification remains technically challenging due to the limitations of conventional methods. Here, a low-cost, fluorescence-based, paper-strip immunoassay is presented for rapid and semi-quantitative estimation of EV concentration, inspired by pH strips. The assay utilizes nitrocellulose membranes functionalized with capture antibodies (anti-CD63, CD9, CD81) and fluorescent dye (ExoBrite™) for EV detection. Systematic optimization of assay parameters—including dye application sequence, incubation time, antibody configuration, and dye concentration—revealed that labeling EVs with dye and incubating on the nitrocellulose paper strips for 20 min yielded the strongest and most reproducible signal. A 200× dilution of ExoBrite™ dye was determined to provide the best balance between sensitivity and specificity. A standard curve generated through twofold serial dilution of EVs from ovarian cancer cell culture medium confirmed a positive, concentration-dependent fluorescence response, establishing a usable dynamic range. Compared to existing technologies, this platform enables fast, simple-to-implement EV quantification using minimal sample volume and equipment. The simplicity and scalability of the method offer strong potential for use in clinical diagnostics and EV research applications. Full article

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

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13 pages, 1455 KiB

Open AccessReview

Quantification of Cisplatin Encapsulated in Nanomedicine: An Overview

by Ziwen Zhang, Jiayu Chen, Tao Wen, Hong Deng, Yiyi Zhang, Hua Guo, Hui Chang, Haiyan Xu and Weiqi Zhang

Biosensors 2025, 15(5), 293; https://doi.org/10.3390/bios15050293 - 6 May 2025

Abstract

Cisplatin, which kills cancer cells mainly through DNA crosslinking, has been widely used as a first-line chemotherapeutic agent although it also causes severe side effects. To improve anticancer outcomes, various types of cisplatin-based nanomedicines have been developed, either through direct incorporation or coordination [...] Read more.

Cisplatin, which kills cancer cells mainly through DNA crosslinking, has been widely used as a first-line chemotherapeutic agent although it also causes severe side effects. To improve anticancer outcomes, various types of cisplatin-based nanomedicines have been developed, either through direct incorporation or coordination of cisplatin within nanoparticles (NPs). During the formulation and characterization of cisplatin-loaded NPs, quantitative determination of cisplatin is crucial for both clinically used and newly developed NPs. While NPs facilitate cisplatin delivery, the use of different nanomaterials inevitably complicates its determination and increases the cost of quantification. Currently, there is still a significant demand for an accurate, simple, and cost-effective method to determine cisplatin in NPs, which would facilitate the screening and quality control of cisplatin-based nanomedicines. This review aims to discuss the main strategies for quantifying cisplatin, following a summary of the main types of cisplatin-loaded NPs. Application examples of cisplatin determination in NPs are provided, and the key features of each quantification strategy are compared. In addition, NP-based electrochemical sensors are included as an emerging approach for characterizing cisplatin loaded in NPs. Rational selection of an appropriate cisplatin determination method for NPs according to the quantification principle and specific drug-delivery settings is highly recommended. Full article

(This article belongs to the Special Issue Recent Developments in Nanomaterial-Based Electrochemical Biosensors)

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45 pages, 15218 KiB

Open AccessReview

Comprehensive Analysis of Advancement in Optical Biosensing Techniques for Early Detection of Cancerous Cells

by Ayushman Ramola, Amit Kumar Shakya and Arik Bergman

Biosensors 2025, 15(5), 292; https://doi.org/10.3390/bios15050292 - 5 May 2025

Abstract

This investigation presents an overview of various optical biosensors utilized for the detection of cancer cells. It covers a comprehensive range of technologies, including surface plasmon resonance

(S P R)

sensors, which exploit changes in refractive index

(R I)

[...] Read more.

This investigation presents an overview of various optical biosensors utilized for the detection of cancer cells. It covers a comprehensive range of technologies, including surface plasmon resonance

(S P R)

sensors, which exploit changes in refractive index

(R I)

at the sensor surface to detect biomolecular interactions. Localized surface plasmon resonance

(L S P R)

sensors offer high sensitivity and versatility in detecting cancer biomarkers. Colorimetric sensors, based on color changes induced via specific biochemical reactions, provide a cost-effective and simple approach to cancer detection. Sensors based on fluorescence work using the light emitted from fluorescent molecules detect cancer-specific targets with specificity and high sensitivity. Photonics and waveguide sensors utilize optical waveguides to detect changes in light propagation, offering real-time and label-free detection of cancer biomarkers. Raman spectroscopy-based sensors utilize surface-enhanced Raman scattering

(S E R S)

to provide molecular fingerprint information for cancer diagnosis. Lastly, fiber optic sensors offer flexibility and miniaturization, making them suitable for in vivo and point-of-care applications in cancer detection. This study provides insights into the principles, applications, and advancements of these optical biosensors in cancer diagnostics, highlighting their potential in improving early detection and patient outcomes. Full article

(This article belongs to the Special Issue Fiber Optic Biosensors: Advancements and Applications)

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12 pages, 3280 KiB

Open AccessArticle

A Dual-Signal Electrochemiluminescence Sensor for Kanamycin Detection Based on a Self-Enhanced Zr MOF and Single Co-Reactant Competition Mechanism

by Yawen Zhu, Xuemei Wang, Zhiyong Yan, Feifei Zhang, Jianfei Xia, Lili Lv and Zonghua Wang

Biosensors 2025, 15(5), 291; https://doi.org/10.3390/bios15050291 - 5 May 2025

Abstract

The dual-signal output self-calibration mode reduces the false positive and negative signals of electrochemiluminescence (ECL) aptamer sensors. A competitive dual-signal ECL platform was designed for the ultrasensitive detection of kanamycin (KAN) using a zirconium metal–organic framework (Zr MOF) and Luminol as ECL emitters. [...] Read more.

The dual-signal output self-calibration mode reduces the false positive and negative signals of electrochemiluminescence (ECL) aptamer sensors. A competitive dual-signal ECL platform was designed for the ultrasensitive detection of kanamycin (KAN) using a zirconium metal–organic framework (Zr MOF) and Luminol as ECL emitters. To enhance the ECL efficiency, a co-reactant (polyethyleneimine, PEI) was covalently bound to the Zr MOF to achieve self-enhanced ECL. Based on the selective interaction between KAN and its aptamer, the Luminol/KAN/Zr MOF-PEI “sandwich” structure was immobilized on the electrode surface. The competition for PEI between emitters increased the Luminol ECL signal and decreased the Zr MOF’s ECL signal. The ratio in ECL signals between the two competitive emitters enabled the quantitative analysis of KAN, achieving a detection limit as low as 7.86 × 10⁻⁴ ng/mL. This study elucidated the synergistic mechanism between self-enhanced ECL and ECL competition, offering a novel approach for constructing dual-signal ECL sensors using a single co-reactant. Full article

(This article belongs to the Special Issue Progress in Electrochemiluminescence Biosensors)

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54 pages, 21736 KiB

Open AccessReview

Whole Cells of Microorganisms—A Powerful Bioanalytical Tool for Measuring Integral Parameters of Pollution: A Review

by Maxim Cheliukanov, George Gurkin, Roman Perchikov, Anastasia Medvedeva, Tatyana Lavrova, Tatyana Belousova, Aleksandra Titova, Yulia Plekhanova, Sergei Tarasov, Anna Kharkova, Vyacheslav Arlyapov, Philippe Mandin, Hideaki Nakamura and Anatoly Reshetilov

Biosensors 2025, 15(5), 290; https://doi.org/10.3390/bios15050290 - 4 May 2025

Abstract

Microbial biosensors are bioanalytical devices that can measure the toxicity of pollutants or detect specific substances. This is the greatest advantage of microbial biosensors which use whole cells of microorganisms as powerful tools for measuring integral parameters of environmental pollution. This review explores [...] Read more.

Microbial biosensors are bioanalytical devices that can measure the toxicity of pollutants or detect specific substances. This is the greatest advantage of microbial biosensors which use whole cells of microorganisms as powerful tools for measuring integral parameters of environmental pollution. This review explores the core principles of microbial biosensors including biofuel devices, emphasizing their capacity to evaluate biochemical oxygen demand (BOD), toxicity, heavy metals, surfactants, phenols, pesticides, inorganic pollutants, and microbiological contamination. However, practical challenges, such as sensitivity to environmental factors like pH, salinity, and the presence of competing substances, continue to hinder their broader application and long-term stability. The performance of these biosensors is closely tied to both technological advancement and the scientific understanding of biological systems, which influence data interpretation and device optimization. The review further examines cutting-edge developments, including the integration of electroactive biofilms with nanomaterials, molecular biology techniques, and artificial intelligence, all of which significantly enhance biosensor functionality and analytical accuracy. Commercial implementations and improvement strategies are also discussed, providing a comprehensive overview of the state-of-the-art in this field. Overall, this work consolidates recent progress and identifies both the potential and limitations of microbial biosensors, offering valuable insights into their future development for environmental monitoring. Full article

(This article belongs to the Special Issue Microbial Biosensor: From Design to Applications—2nd Edition)

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30 pages, 5773 KiB

Open AccessArticle

A Novel Working Memory Task-Induced EEG Response (WM-TIER) Feature Extraction Framework for Detecting Alzheimer’s Disease and Mild Cognitive Impairment

by Yi-Hung Liu, Thanh-Tung Trinh, Chia-Fen Tsai, Jie-Kai Yang, Chun-Ying Lee and Chien-Te Wu

Biosensors 2025, 15(5), 289; https://doi.org/10.3390/bios15050289 - 4 May 2025

Abstract

The electroencephalography (EEG)-based approach provides a promising low-cost and non-invasive approach to the early detection of pathological cognitive decline. However, current studies predominantly utilize EEGs from resting state (rsEEG) or task-state (task EEG), posing challenges to classification performances due to the unconstrainted nature [...] Read more.

The electroencephalography (EEG)-based approach provides a promising low-cost and non-invasive approach to the early detection of pathological cognitive decline. However, current studies predominantly utilize EEGs from resting state (rsEEG) or task-state (task EEG), posing challenges to classification performances due to the unconstrainted nature of mind wandering during resting state or the inherent inter-participant variability from task execution. To address these limitations, this study proposes a novel feature extraction framework, working memory task-induced EEG response (WM-TIER), which adjusts task EEG features by rsEEG features and leverages the often-overlooked inter-state changes of EEGs. We recorded EEGs from 21 AD individuals, 24 MCI individuals, and 27 healthy controls (HC) during both resting and working memory task conditions. We then compared the classification performance of WM-TIER to the conventional rsEEG or task EEG framework. For each framework, three feature types were examined: relative power, spectral coherence, and filter-bank phase lag index (FB-PLI). Our results indicated that FB-PLI-based WM-TIER features provide (1) better AD/MCI versus HC classification accuracy than rsEEG and task EEG frameworks and (2) high accuracy for three-class classification of AD vs. MCI vs. HC. These findings suggest that the EEG-based rest-to-task state transition can be an effective neural marker for the early detection of pathological cognitive decline. Full article

(This article belongs to the Section Biosensors and Healthcare)

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48 pages, 13318 KiB

Open AccessReview

Recent Progress in MXene-Based Materials for Supercapacitors and Electrochemical Sensing Applications

by Khursheed Ahmad and Tae Hwan Oh

Biosensors 2025, 15(5), 288; https://doi.org/10.3390/bios15050288 - 3 May 2025

Abstract

In recent years, MXene-based materials have received extensive interest for a variety of applications, including energy storage, solar cells, sensors, photo-catalysis, etc., due to their extraordinary optoelectronic and physicochemical properties. MXene-based electrode materials exhibit excellent electrochemical properties for supercapacitors (SCs) and electrochemical sensing [...] Read more.

In recent years, MXene-based materials have received extensive interest for a variety of applications, including energy storage, solar cells, sensors, photo-catalysis, etc., due to their extraordinary optoelectronic and physicochemical properties. MXene-based electrode materials exhibit excellent electrochemical properties for supercapacitors (SCs) and electrochemical sensing technologies due to the presence of acceptable electrocatalytic characteristics. Herein, we reviewed publications from recent years on the development of MXenes and their composites for SCs and electrochemical sensors. MXene-based materials with polymers, metal oxides, metal sulfides or selenides; metal–organic frameworks (MOFs); layered double hydroxides (LDHs); and carbon-based materials such as graphene, carbon nanotubes, etc., have been reviewed for their potential applications in SCs. MXene-based hybrid composites have also been reviewed for electrochemical sensing applications. Furthermore, challenges and future perspectives are discussed. It is expected that the present article will be beneficial for scientists working on the modification of MXene-based materials for SCs and electrochemical sensing technologies. Full article

(This article belongs to the Special Issue Biosensors Based on Functional Nanomaterials)

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