Biosensors

16 pages, 1333 KiB

Open AccessArticle

CampyTube: Seamless Integration of a Molecular Test and Lateral Flow Detection of Campylobacter in a Single Vial

by Natalia Sandetskaya, Andreas Kölsch, Kai Mattern, Vanessa Vater, Dirk Kuhlmeier and Florian Priller

Biosensors 2025, 15(8), 497; https://doi.org/10.3390/bios15080497 (registering DOI) - 1 Aug 2025

Abstract

Background: The efficient control of hygiene and Campylobacter’s contamination status at various steps of poultry meat production is essential for the prevention of Campylobacter transmission to humans. Microbiological methods are laborious and time-consuming, and molecular methods of detection are often too skill- [...] Read more.

Background: The efficient control of hygiene and Campylobacter’s contamination status at various steps of poultry meat production is essential for the prevention of Campylobacter transmission to humans. Microbiological methods are laborious and time-consuming, and molecular methods of detection are often too skill- and infrastructure-demanding. Methods: We have developed CampyTube, a simple and user-friendly format for the integration of isothermal DNA amplification with embedded instrument-free detection on a miniaturized lateral flow test in a single vial. All test components, from the dry amplification reagents to the mini lateral flow tests, are incorporated into a standard single vial, which is closed after the addition of the liquid sample and never has to be opened again. This ensures the absolute prevention of carry-over contamination and makes the system very safe and simple to use in point-of-need settings. Results: As few as 60 Campylobacter genome copies per reaction could be successfully detected with CampyTube. We have primarily developed and evaluated CampyTube for the detection of Campylobacter in chicken neck skin samples and could reach 100% sensitivity and 100% specificity in the samples exceeding the regulatory limit of 1000 CFU/g confirmed microbiologically, while the sensitivity in all samples that tested positive using qPCR (1.4 × 10²–2.5 × 10⁶ genome copies/g) was 71.1%. We discuss the impact of sample preparation on CampyTube performance and suggest further options for test optimization. Conclusions: CampyTube is a highly versatile and efficient, yet simple, affordable, and material-saving system that can be adapted for other targets and sample types. Full article

(This article belongs to the Special Issue Biosensors for Monitoring and Diagnostics)

26 pages, 3787 KiB

Open AccessReview

Insights to Resistive Pulse Sensing of Microparticle and Biological Cells on Microfluidic Chip

by Yiming Yao, Kai Zhao, Haoxin Jia, Zhengxing Wei, Yiyang Huo, Yi Zhang and Kaihuan Zhang

Biosensors 2025, 15(8), 496; https://doi.org/10.3390/bios15080496 (registering DOI) - 1 Aug 2025

Abstract

Since the initial use of biological ion channels to detect single-stranded genomic base pair differences, label-free and highly sensitive resistive pulse sensing (RPS) with nanopores has made remarkable progress in single-molecule analysis. By monitoring transient ionic current disruptions caused by molecules translocating through [...] Read more.

Since the initial use of biological ion channels to detect single-stranded genomic base pair differences, label-free and highly sensitive resistive pulse sensing (RPS) with nanopores has made remarkable progress in single-molecule analysis. By monitoring transient ionic current disruptions caused by molecules translocating through a nanopore, this technology offers detailed insights into the structure, charge, and dynamics of the analytes. In this work, the RPS platforms based on biological, solid-state, and other sensing pores, detailing their latest research progress and applications, are reviewed. Their core capability is the high-precision characterization of tiny particles, ions, and nucleotides, which are widely used in biomedicine, clinical diagnosis, and environmental monitoring. However, current RPS methods involve bottlenecks, including limited sensitivity (weak signals from sub-nanometer targets with low SNR), complex sample interference (high false positives from ionic strength, etc.), and field consistency (solid-state channel drift, short-lived bio-pores failing POCT needs). To overcome this, bio-solid-state fusion channels, in-well reactors, deep learning models, and transfer learning provide various options. Evolving into an intelligent sensing ecosystem, RPS is expected to become a universal platform linking basic research, precision medicine, and on-site rapid detection. Full article

(This article belongs to the Special Issue Advanced Microfluidic Devices and Lab-on-Chip (Bio)sensors)

17 pages, 3738 KiB

Open AccessArticle

Beyond Spheres: Evaluating Gold Nano-Flowers and Gold Nano-Stars for Enhanced Aflatoxin B1 Detection in Lateral Flow Immunoassays

by Vinayak Sharma, Bilal Javed, Hugh J. Byrne and Furong Tian

Biosensors 2025, 15(8), 495; https://doi.org/10.3390/bios15080495 (registering DOI) - 1 Aug 2025

Abstract

The lateral flow immunoassay (LFIA) is a widely utilized, rapid diagnostic technique characterized by its short analysis duration, cost efficiency, visual result interpretation, portability and suitability for point-of-care applications. However, conventional LFIAs have limited sensitivity, a challenge that can be overcome by the [...] Read more.

The lateral flow immunoassay (LFIA) is a widely utilized, rapid diagnostic technique characterized by its short analysis duration, cost efficiency, visual result interpretation, portability and suitability for point-of-care applications. However, conventional LFIAs have limited sensitivity, a challenge that can be overcome by the introduction of gold nanoparticles, which provide enhanced sensitivity and selectivity (compared, for example, to latex beads or carbon nanoparticles) for the detection of target analytes, due to their optical properties, chemical stability and ease of functionalization. In this work, gold nanoparticle-based LFIAs are developed for the detection of aflatoxin B1, and the relative performance of different morphology particles is evaluated. LFIA using gold nano-labels allowed for aflatoxin B1 detection over a range of 0.01 ng/mL–100 ng/mL. Compared to spherical gold nanoparticles and gold nano-flowers, star-shaped gold nanoparticles show increased antibody binding efficiency of 86% due to their greater surface area. Gold nano-stars demonstrated the highest sensitivity, achieving a limit of detection of 0.01ng/mL, surpassing the performance of both spherical gold nanoparticles and gold nano-flowers. The use of star-shaped particles as nano-labels has demonstrated a five-fold improvement in sensitivity, underscoring the potential of integrating diverse nanostructures into LFIA for significantly improving analyte detection. Moreover, the robustness and feasibility of gold nano-stars employed as labels in LFIA was assessed in detecting aflatoxin B1 in a wheat matrix. Improved sensitivity with gold nano-stars holds promise for applications in food safety monitoring, public health diagnostics and rapid point-of-care diagnostics. This work opens the pathway for further development of LFIA utilizing novel nanostructures to achieve unparallel precision in diagnostics and sensing. Full article

(This article belongs to the Special Issue Bioassays and Biosensors for Rapid Detection and Analysis (2nd Edition))

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29 pages, 1477 KiB

Open AccessReview

Bioinformation and Monitoring Technology for Environmental DNA Analysis: A Review

by Hyo Jik Yoon, Joo Hyeong Seo, Seung Hoon Shin, Mohamed A. A. Abedlhamid and Seung Pil Pack

Biosensors 2025, 15(8), 494; https://doi.org/10.3390/bios15080494 (registering DOI) - 1 Aug 2025

Abstract

Environmental DNA (eDNA) analysis has emerged as a transformative tool in environmental monitoring, enabling non-invasive detection of species and microbial communities across diverse ecosystems. This study systematically reviews the role of bioinformation technology in eDNA analysis, focusing on methodologies and applications across air, [...] Read more.

Environmental DNA (eDNA) analysis has emerged as a transformative tool in environmental monitoring, enabling non-invasive detection of species and microbial communities across diverse ecosystems. This study systematically reviews the role of bioinformation technology in eDNA analysis, focusing on methodologies and applications across air, soil, groundwater, sediment, and aquatic environments. Advances in molecular biology, high-throughput sequencing, bioinformatics tools, and field-deployable detection systems have significantly improved eDNA detection sensitivity, allowing for early identification of invasive species, monitoring ecosystem health, and tracking pollutant degradation processes. Airborne eDNA monitoring has demonstrated potential for assessing microbial shifts due to air pollution and tracking pathogen transmission. In terrestrial environments, eDNA facilitates soil and groundwater pollution assessments and enhances understanding of biodegradation processes. In aquatic ecosystems, eDNA serves as a powerful tool for biodiversity assessment, invasive species monitoring, and wastewater-based epidemiology. Despite its growing applicability, challenges remain, including DNA degradation, contamination risks, and standardization of sampling protocols. Future research should focus on integrating eDNA data with remote sensing, machine learning, and ecological modeling to enhance predictive environmental monitoring frameworks. As technological advancements continue, eDNA-based approaches are poised to revolutionize environmental assessment, conservation strategies, and public health surveillance. Full article

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

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15 pages, 2400 KiB

Open AccessArticle

Robust Prediction of Cardiorespiratory Signals from a Multimodal Physiological System on the Upper Arm

by Kimberly L. Branan, Rachel Kurian, Justin P. McMurray, Madhav Erraguntla, Ricardo Gutierrez-Osuna and Gerard L. Coté

Biosensors 2025, 15(8), 493; https://doi.org/10.3390/bios15080493 (registering DOI) - 1 Aug 2025

Abstract

Many commercial wearable sensor systems typically rely on a single continuous cardiorespiratory sensing modality, photoplethysmography (PPG), which suffers from inherent biases (i.e., differences in skin tone) and noise (e.g., motion and pressure artifacts). In this research, we present a wearable device that provides [...] Read more.

Many commercial wearable sensor systems typically rely on a single continuous cardiorespiratory sensing modality, photoplethysmography (PPG), which suffers from inherent biases (i.e., differences in skin tone) and noise (e.g., motion and pressure artifacts). In this research, we present a wearable device that provides robust estimates of cardiorespiratory variables by combining three physiological signals from the upper arm: multiwavelength PPG, single-sided electrocardiography (SS-ECG), and bioimpedance plethysmography (BioZ), along with an inertial measurement unit (IMU) providing 3-axis accelerometry and gyroscope information. We evaluated the multimodal device on 16 subjects by its ability to estimate heart rate (HR) and breathing rate (BR) in the presence of various static and dynamic noise sources (e.g., skin tone and motion). We proposed a hierarchical approach that considers the subject’s skin tone and signal quality to select the optimal sensing modality for estimating HR and BR. Our results indicate that, when estimating HR, there is a trade-off between accuracy and robustness, with SS-ECG providing the highest accuracy (low mean absolute error; MAE) but low reliability (higher rates of sensor failure), and PPG/BioZ having lower accuracy but higher reliability. When estimating BR, we find that fusing estimates from multiple modalities via ensemble bagged tree regression outperforms single-modality estimates. These results indicate that multimodal approaches to cardiorespiratory monitoring can overcome the accuracy–robustness trade-off that occurs when using single-modality approaches. Full article

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

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14 pages, 3666 KiB

Open AccessArticle

A Sensitive Sandwich-Type Electrochemical Immunosensor for Carbohydrate Antigen 19-9 Based on Covalent Organic Frameworks

by Ting Wu, Rongfang Chen, Yaqin Duan, Longfei Miao, Yongmei Zhu and Li Wang

Biosensors 2025, 15(8), 492; https://doi.org/10.3390/bios15080492 (registering DOI) - 1 Aug 2025

Abstract

Since carbohydrate antigen 19-9 (CA 19-9) is a significant biomarker for the clinical diagnosis and treatment of pancreatic cancer, a sensitive sandwich-type immunosensor was proposed with an epoxy functionalized covalent organic framework (EP-COF_TTA-DHTA) as the antibody carrier and an electroactive COF [...] Read more.

Since carbohydrate antigen 19-9 (CA 19-9) is a significant biomarker for the clinical diagnosis and treatment of pancreatic cancer, a sensitive sandwich-type immunosensor was proposed with an epoxy functionalized covalent organic framework (EP-COF_TTA-DHTA) as the antibody carrier and an electroactive COF_{TTA-2,6-NA(OH)2} as the signal amplification probe for the sensitive detection of CA 19-9. The flexible covalent linkage between the epoxy-functionalized EP-COF_TTA-DHTA and the antibodies was employed to improve the dynamics of the antigen–antibody interaction significantly. Meanwhile, AuNPs@COF_{TTA-2,6-NA(OH)2} with abundant electroactive sites enhanced the current response of the immunoreaction significantly. After optimizing the incubation time and concentration of the antibody, CA 19-9 was quantitatively detected by differential pulse voltammetry (DPV) based on the sensitive sandwich-type immunosensor with a low detection limit of 0.0003 U/mL and a wide linear range of 0.0009–100 U/mL. The electrochemical immunosensor exhibits high specificity, stability and repeatability, and it provides a feasible and efficient method for the pathologic analysis and treatment of tumor markers. Full article

(This article belongs to the Special Issue Advances in Biosensors Based on Framework Materials)

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32 pages, 12213 KiB

Open AccessReview

Capacitive Sensors for Label-Free Detection in High-Ionic-Strength Bodily Fluids: A Review

by Seerat Sekhon, Richard Bayford and Andreas Demosthenous

Biosensors 2025, 15(8), 491; https://doi.org/10.3390/bios15080491 - 30 Jul 2025

Abstract

Capacitive sensors are platforms that enable label-free, real-time detection at low non-perturbing voltages. These sensors do not rely on Faradaic processes, thereby eliminating the need for redox-active species and simplifying system integration for point-of-care diagnostics. However, their sensitivity in high-ionic-strength solutions, such as [...] Read more.

Capacitive sensors are platforms that enable label-free, real-time detection at low non-perturbing voltages. These sensors do not rely on Faradaic processes, thereby eliminating the need for redox-active species and simplifying system integration for point-of-care diagnostics. However, their sensitivity in high-ionic-strength solutions, such as bodily fluids, is limited due to a reduced Debye length and non-specific interactions. The present review highlights advances in material integration, surface modification, and signal enhancement techniques to mitigate the challenges of deploying capacitive sensors in biofluids (sweat, saliva, blood, serum). This work further expands on the promise of such sensors for advancing liquid biopsies and highlights key technical challenges in translating capacitive systems to clinics. Full article

(This article belongs to the Special Issue Novel Designs and Applications for Electrochemical Biosensors)

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13 pages, 2697 KiB

Open AccessCommunication

Oxidation-Active Radical TTM-DMODPA for Catalysis-Free Hydrogen Peroxide Colorimetric Sensing

by Qingmei Zhong, Xiaomei Rong, Tingting Wu and Chuan Yan

Biosensors 2025, 15(8), 490; https://doi.org/10.3390/bios15080490 - 29 Jul 2025

Abstract

As a crucial reactive oxygen species, hydrogen peroxide (H₂O₂) serves as both a physiological regulator and a pathological indicator in human systems. Its urinary concentration has emerged as a valuable biomarker for assessing metabolic disorders and renal function. While [...] Read more.

As a crucial reactive oxygen species, hydrogen peroxide (H₂O₂) serves as both a physiological regulator and a pathological indicator in human systems. Its urinary concentration has emerged as a valuable biomarker for assessing metabolic disorders and renal function. While conventional colorimetric determination methods predominantly employ enzymatic or nanozyme catalysts, we present an innovative non-catalytic approach utilizing the redox-responsive properties of organic neutral radicals. Specifically, we designed and synthesized a novel radical TTM-DMODPA based on the tris (2,4,6-trichlorophenyl) methyl (TTM) scaffold, which exhibits remarkable optical tunability and oxidative sensitivity. This system enables dual-mode H₂O₂ quantification: (1) UV-vis spectrophotometry (linear range: 2.5–250 μmol/L, LOD: 1.275 μmol/L) and (2) smartphone-based visual analysis (linear range: 2.5–250 μmol/L, LOD: 3.633 μmol/L), the latter being particularly suitable for point-of-care testing. Validation studies using urine samples demonstrated excellent recovery rates (96–104%), confirming the method’s reliability for real-sample applications. Our work establishes a portable, instrument-free platform for urinary H₂O₂ determination, with significant potential in clinical diagnostics and environmental monitoring. Full article

(This article belongs to the Section Optical and Photonic Biosensors)

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14 pages, 1284 KiB

Open AccessArticle

Non-Enzymatic Selective Detection of Histamine in Fishery Product Samples on Boron-Doped Diamond Electrodes

by Hiroshi Aoki, Risa Miyazaki and Yasuaki Einaga

Biosensors 2025, 15(8), 489; https://doi.org/10.3390/bios15080489 - 29 Jul 2025

Abstract

Histamine sensing that uses enzymatic reactions is the most common form of testing due to its selectivity for histamine. However, enzymes are difficult to store for long periods of time, and the inactivation of enzymes decreases the reliability of the results. In this [...] Read more.

Histamine sensing that uses enzymatic reactions is the most common form of testing due to its selectivity for histamine. However, enzymes are difficult to store for long periods of time, and the inactivation of enzymes decreases the reliability of the results. In this study, we developed a novel, quick, and easily operated histamine sensing technique that takes advantage of the histamine redox reaction and does not require enzyme-based processes. Because the redox potential of histamine is relatively high, we used a boron-doped diamond (BDD) electrode that has a wide potential window. At pH 8.4, which is between the acidity constant of histamine and the isoelectric point of histidine, it was found that an oxygen-terminated BDD surface successfully detected histamine, both selectively and exclusively. Measurements of the sensor’s responses to extracts from fish meat samples that contained histamine at various concentrations revealed that the sensor responds linearly to the histamine concentration, thus allowing it to be used as a calibration curve. The sensor was used to measure histamine in another fish meat sample treated as an unknown sample, and the response was fitted to the calibration curve to perform an inverse estimation. When estimated in this way, the histamine concentration matched the certified value within the range of error. A more detailed examination showed that the sensor response was little affected by the histidine concentration in the sample. The detection limit was 20.9 ppm, and the linear response range was 0–150 ppm. This confirms that this sensing method can be used to measure standard histamine concentrations. Full article

(This article belongs to the Special Issue Advanced Biosensors for Food and Agriculture Safety)

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26 pages, 4449 KiB

Open AccessReview

Recent Progress in Electrocatalysts for Hydroquinone Electrochemical Sensing Application

by Mohammad Aslam, Khursheed Ahmad, Saood Ali, Khaled Hamdy and Danishuddin

Biosensors 2025, 15(8), 488; https://doi.org/10.3390/bios15080488 - 28 Jul 2025

Abstract

This review article compiled previous reports in the fabrication of hydroquinone (HQ) electrochemical sensors using differently modified electrodes. The electrode materials, which are also called electrocatalysts, play a crucial role in electrochemical detection of biomolecules and toxic substances. Metal oxides, MXenes, carbon-based materials [...] Read more.

This review article compiled previous reports in the fabrication of hydroquinone (HQ) electrochemical sensors using differently modified electrodes. The electrode materials, which are also called electrocatalysts, play a crucial role in electrochemical detection of biomolecules and toxic substances. Metal oxides, MXenes, carbon-based materials such as reduced graphene oxide (rGO), carbon nanotubes (CNTs), layered double hydroxides (LDH), metal sulfides, and hybrid composites were extensively utilized in the fabrication of HQ sensors. The electrochemical performance, including limit of detection, linearity, sensitivity, selectivity, stability, reproducibility, repeatability, and recovery for real-time sensing of the HQ sensors have been discussed. The limitations, challenges, and future directions are also discussed in the conclusion section. It is believed that the present review article may benefit researchers who are involved in the development of HQ sensors and catalyst preparation for electrochemical sensing of other toxic substances. Full article

(This article belongs to the Special Issue Advanced Materials for Electrochemical Sensors and Biosensors Development-2nd Edition)

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33 pages, 8681 KiB

Open AccessReview

AI-Empowered Electrochemical Sensors for Biomedical Applications: Technological Advances and Future Challenges

by Yafeng Liu, Xiaohui Liu, Xuemei Wang and Hui Jiang

Biosensors 2025, 15(8), 487; https://doi.org/10.3390/bios15080487 - 28 Jul 2025

Abstract

Biomarkers play a pivotal role in disease diagnosis, therapeutic efficacy evaluation, prognostic assessment, and drug screening. However, the trace concentrations of these markers in complex physiological environments pose significant challenges to efficient detection. It is necessary to avoid interference from non-specific signals, which [...] Read more.

Biomarkers play a pivotal role in disease diagnosis, therapeutic efficacy evaluation, prognostic assessment, and drug screening. However, the trace concentrations of these markers in complex physiological environments pose significant challenges to efficient detection. It is necessary to avoid interference from non-specific signals, which may lead to misjudgment of other substances as biomarkers and affect the accuracy of detection results. With the rapid advancements in electrochemical technologies and artificial intelligence (AI) algorithms, intelligent electrochemical biosensors have emerged as a promising approach for biomedical detection, offering speed, specificity, high sensitivity, and accuracy. This review focuses on elaborating the latest applications of AI-empowered electrochemical biosensors in the biomedical field, including disease diagnosis, treatment monitoring, drug development, and wearable devices. AI algorithms can further improve the accuracy, sensitivity, and repeatability of electrochemical sensors through the screening and performance prediction of sensor materials, as well as the feature extraction and noise reduction suppression of sensing signals. Even in complex physiological microenvironments, they can effectively address common issues such as electrode fouling, poor signal-to-noise ratio, chemical interference, and matrix effects. This work may provide novel insights for the development of next-generation intelligent biosensors for precision medicine. Full article

(This article belongs to the Special Issue Artificial Intelligence (AI) and Machine Learning (ML) in Biosensors: Innovation, Application, and Challenge)

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29 pages, 5407 KiB

Open AccessArticle

Noncontact Breathing Pattern Monitoring Using a 120 GHz Dual Radar System with Motion Interference Suppression

by Zihan Yang, Yinzhe Liu, Hao Yang, Jing Shi, Anyong Hu, Jun Xu, Xiaodong Zhuge and Jungang Miao

Biosensors 2025, 15(8), 486; https://doi.org/10.3390/bios15080486 - 28 Jul 2025

Abstract

Continuous monitoring of respiratory patterns is essential for disease diagnosis and daily health care. Contact medical devices enable reliable respiratory monitoring, but can cause discomfort and are limited in some settings. Radar offers a noncontact respiration measurement method for continuous, real-time, high-precision monitoring. [...] Read more.

Continuous monitoring of respiratory patterns is essential for disease diagnosis and daily health care. Contact medical devices enable reliable respiratory monitoring, but can cause discomfort and are limited in some settings. Radar offers a noncontact respiration measurement method for continuous, real-time, high-precision monitoring. However, it is difficult for a single radar to characterize the coordination of chest and abdominal movements during measured breathing. Moreover, motion interference during prolonged measurements can seriously affect accuracy. This study proposes a dual radar system with customized narrow-beam antennas and signals to measure the chest and abdomen separately, and an adaptive dynamic time warping (DTW) algorithm is used to effectively suppress motion interference. The system is capable of reconstructing respiratory waveforms of the chest and abdomen, and robustly extracting various respiratory parameters via motion interference. Experiments on 35 healthy subjects, 2 patients with chronic obstructive pulmonary disease (COPD), and 1 patient with heart failure showed a high correlation between radar and respiratory belt signals, with correlation coefficients of 0.92 for both the chest and abdomen, a root mean square error of 0.80 bpm for the respiratory rate, and a mean absolute error of 3.4° for the thoracoabdominal phase angle. This system provides a noncontact method for prolonged respiratory monitoring, measurement of chest and abdominal asynchrony and apnea detection, showing promise for applications in respiratory disorder detection and home monitoring. Full article

(This article belongs to the Section Wearable Biosensors)

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19 pages, 3862 KiB

Open AccessArticle

Estimation of Total Hemoglobin (SpHb) from Facial Videos Using 3D Convolutional Neural Network-Based Regression

by Ufuk Bal, Faruk Enes Oguz, Kubilay Muhammed Sunnetci, Ahmet Alkan, Alkan Bal, Ebubekir Akkuş, Halil Erol and Ahmet Çağdaş Seçkin

Biosensors 2025, 15(8), 485; https://doi.org/10.3390/bios15080485 - 25 Jul 2025

Abstract

Hemoglobin plays a critical role in diagnosing various medical conditions, including infections, trauma, hemolytic disorders, and Mediterranean anemia, which is particularly prevalent in Mediterranean populations. Conventional measurement methods require blood sampling and laboratory analysis, which are often time-consuming and impractical during emergency situations [...] Read more.

Hemoglobin plays a critical role in diagnosing various medical conditions, including infections, trauma, hemolytic disorders, and Mediterranean anemia, which is particularly prevalent in Mediterranean populations. Conventional measurement methods require blood sampling and laboratory analysis, which are often time-consuming and impractical during emergency situations with limited medical infrastructure. Although portable oximeters enable non-invasive hemoglobin estimation, they still require physical contact, posing limitations for individuals with circulatory or dermatological conditions. Additionally, reliance on disposable probes increases operational costs. This study presents a non-contact and automated approach for estimating total hemoglobin levels from facial video data using three-dimensional regression models. A dataset was compiled from 279 volunteers, with synchronized acquisition of facial video and hemoglobin values using a commercial pulse oximeter. After preprocessing, the dataset was divided into training, validation, and test subsets. Three 3D convolutional regression models, including 3D CNN, channel attention-enhanced 3D CNN, and residual 3D CNN, were trained, and the most successful model was implemented in a graphical interface. Among these, the residual model achieved the most favorable performance on the test set, yielding an RMSE of 1.06, an MAE of 0.85, and a Pearson correlation coefficient of 0.73. This study offers a novel contribution by enabling contactless hemoglobin estimation from facial video using 3D CNN-based regression techniques. Full article

(This article belongs to the Special Issue Non-Invasive Biosensors for Clinical Diagnostics and Healthcare Monitoring)

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17 pages, 7485 KiB

Open AccessReview

Organic Afterglow Materials for Tumor Diagnosis and Therapy

by Xiayi Chen, Bin Li, Baoli Yin, Dong Xu and Youjuan Wang

Biosensors 2025, 15(8), 484; https://doi.org/10.3390/bios15080484 - 25 Jul 2025

Abstract

Organic afterglow nanoparticles (OANs) represent a unique class of optical materials capable of sustaining luminescence after excitation cessation. Owing to their exceptional design flexibility, tunable optical properties, and favorable biosafety profiles, OAN-based afterglow imaging has emerged as an advanced modality in tumor diagnosis [...] Read more.

Organic afterglow nanoparticles (OANs) represent a unique class of optical materials capable of sustaining luminescence after excitation cessation. Owing to their exceptional design flexibility, tunable optical properties, and favorable biosafety profiles, OAN-based afterglow imaging has emerged as an advanced modality in tumor diagnosis and therapy. These nanostructures demonstrate significant potential in guiding precision surgical interventions and real-time monitoring of tumor treatment, including photodynamic therapy, photothermal therapy, and immunotherapy. This review systematically analyzes and discusses the luminescence mechanisms of OANs under various excitation sources, with particular emphasis on recent developments in tumor detection and treatment. Additionally, we also discuss the current challenges and future perspectives of using these nanoparticles in this field. Full article

(This article belongs to the Special Issue Single-Molecule Biosensing: Recent Advances and Future Challenges)

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14 pages, 1765 KiB

Open AccessArticle

Microfluidic System Based on Flexible Structures for Point-of-Care Device Diagnostics with Electrochemical Detection

by Kasper Marchlewicz, Robert Ziółkowski, Kamil Żukowski, Jakub Krzemiński and Elżbieta Malinowska

Biosensors 2025, 15(8), 483; https://doi.org/10.3390/bios15080483 - 24 Jul 2025

Abstract

Infectious diseases poses a growing public health challenge. The COVID-19 pandemic has further emphasized the urgent need for rapid, accessible diagnostics. This study presents the development of an integrated, flexible point-of-care (POC) diagnostic system for the rapid detection of Corynebacterium diphtheriae, the [...] Read more.

Infectious diseases poses a growing public health challenge. The COVID-19 pandemic has further emphasized the urgent need for rapid, accessible diagnostics. This study presents the development of an integrated, flexible point-of-care (POC) diagnostic system for the rapid detection of Corynebacterium diphtheriae, the pathogen responsible for diphtheria. The system comprises a microfluidic polymerase chain reaction (micro-PCR) device and an electrochemical DNA biosensor, both fabricated on flexible substrates. The micro-PCR platform offers rapid DNA amplification overcoming the time limitations of conventional thermocyclers. The biosensor utilizes specific molecular recognition and an electrochemical transducer to detect the amplified DNA fragment, providing a clear and direct indication of the pathogen’s presence. The combined system demonstrates the effective amplification and detection of a gene fragment from a toxic strain of C. diphtheriae, chosen due to its increasing incidence. The design leverages lab-on-a-chip (LOC) and microfluidic technologies to minimize reagent use, reduce cost, and support portability. Key challenges in microsystem design—such as flow control, material selection, and reagent compatibility—were addressed through optimized fabrication techniques and system integration. This work highlights the feasibility of using flexible, integrated microfluidic and biosensor platforms for the rapid, on-site detection of infectious agents. The modular and scalable nature of the system suggests potential for adaptation to a wide range of pathogens, supporting broader applications in global health diagnostics. The approach provides a promising foundation for next-generation POC diagnostic tools. Full article

(This article belongs to the Special Issue Microfluidics for Sample Pretreatment)

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24 pages, 4040 KiB

Open AccessReview

Progress in Electrode Materials for the Detection of Nitrofurazone and Nitrofurantoin

by Mohammad Aslam, Saood Ali, Khursheed Ahmad and Danishuddin

Biosensors 2025, 15(8), 482; https://doi.org/10.3390/bios15080482 - 24 Jul 2025

Abstract

Recently, it has been found that electrochemical sensing technology is one of the significant approaches for the monitoring of toxic and hazardous substances in food and the environment. Nitrofurazone (NFZ) and nitrofurantoin (NFT) possess a hazardous influence on the environment, aquatic life, and [...] Read more.

Recently, it has been found that electrochemical sensing technology is one of the significant approaches for the monitoring of toxic and hazardous substances in food and the environment. Nitrofurazone (NFZ) and nitrofurantoin (NFT) possess a hazardous influence on the environment, aquatic life, and human health. Thus, various advanced materials such as graphene, carbon nanotubes, metal oxides, MXenes, layered double hydroxides (LDHs), polymers, metal–organic frameworks (MOFs), metal-based composites, etc. are widely used for the development of nitrofurazone and nitrofurantoin sensors. This review article summarizes the progress in the fabrication of electrode materials for nitrofurazone and nitrofurantoin sensing applications. The performance of the various electrode materials for nitrofurazone and nitrofurantoin monitoring are discussed. Various electrochemical sensing techniques such as square wave voltammetry (SWV), differential pulse voltammetry (DPV), linear sweep voltammetry (LSV), amperometry (AMP), cyclic voltammetry (CV), and chronoamperometry (CA) are discussed for the determination of NFZ and NFT. It is observed that DPV, SWV, and AMP/CA are more sensitive techniques compared to LSV and CV. The challenges, future perspectives, and limitations of NFZ and NFT sensors are also discussed. It is believed that present article may be useful for electrochemists as well materials scientists who are working to design electrode materials for electrochemical sensing applications. Full article

(This article belongs to the Special Issue Advanced Nanomaterials for Electrochemical Biosensing Application)

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13 pages, 1823 KiB

Open AccessArticle

Wearable Personal Uroflowmeter for Measuring Urine Leakage in Women with Incontinence: Feasibility Study

by Ali Attari, Faezeh Shanehsazzadeh, Tana Kirkbride, Carol Day, John O. L. DeLancey and James A. Ashton-Miller

Biosensors 2025, 15(8), 481; https://doi.org/10.3390/bios15080481 - 24 Jul 2025

Abstract

This paper describes a novel wearable personal uroflowmeter and its use to log urine leakage episodes in women. Consisting of a miniature flow rate sensor attached under the urethral meatus, it recorded both urine flow rate and volume during activities of daily living. [...] Read more.

This paper describes a novel wearable personal uroflowmeter and its use to log urine leakage episodes in women. Consisting of a miniature flow rate sensor attached under the urethral meatus, it recorded both urine flow rate and volume during activities of daily living. The sensor communicated with a determining unit incorporating a microcontroller and an inertial measurement unit worn at the waist, facilitating the post-hoc determination of which activities and changes in pose caused leakage. Six women participated in a feasibility study performed in a clinical setting. The results indicate that the uroflowmeter was 97.5% accurate in assessing micturition flow compared to gold standard uroflowmetry and leakage measurements. The system also provides subject-specific information on the relationship between physical activity and urine leakage, thereby eliminating errors due to missing data and recall bias in bladder leakage diaries and circumventing the limitations of office-based uroflowmeters. Full article

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

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37 pages, 13718 KiB

Open AccessReview

Photothermal and Photodynamic Strategies for Diagnosis and Therapy of Alzheimer’s Disease by Modulating Amyloid-β Aggregation

by Fengli Gao, Yupeng Hou, Yaru Wang, Linyuan Liu, Xinyao Yi and Ning Xia

Biosensors 2025, 15(8), 480; https://doi.org/10.3390/bios15080480 - 24 Jul 2025

Abstract

Amyloid-β (Aβ) aggregates are considered as the important factors of Alzheimer’s disease (AD). Multifunctional materials have shown significant effects in the diagnosis and treatment of AD by modulating the aggregation of Aβ and production of reactive oxygen species (ROS). Compared to traditional surgical [...] Read more.

Amyloid-β (Aβ) aggregates are considered as the important factors of Alzheimer’s disease (AD). Multifunctional materials have shown significant effects in the diagnosis and treatment of AD by modulating the aggregation of Aβ and production of reactive oxygen species (ROS). Compared to traditional surgical treatment and radiotherapy, phototherapy has the advantages, including short response time, significant efficacy, and minimal side effects in disease diagnosis and treatment. Recent studies have shown that local thermal energy or singlet oxygen generated by irradiating certain organic molecules or nanomaterials with specific laser wavelengths can effectively degrade Aβ aggregates and depress the generation of ROS, promoting progress in AD diagnosis and therapy. Herein, we outline the development of photothermal therapy (PTT) and photodynamic therapy (PDT) strategies for the diagnosis and therapy of AD by modulating Aβ aggregation. The materials mainly include organic photothermal agents or photosensitizers, polymer materials, metal nanoparticles, quantum dots, carbon-based nanomaterials, etc. In addition, compared to traditional fluorescent dyes, aggregation-induced emission (AIE) molecules have the advantages of good stability, low background signals, and strong resistance to photobleaching for bioimaging. Some AIE-based materials exhibit excellent photothermal and photodynamic effects, showing broad application prospects in the diagnosis and therapy of AD. We further summarize the advances in the detection of Aβ aggregates and phototherapy of AD using AIE-based materials. Full article

(This article belongs to the Special Issue Biosensors Based on Self-Assembly and Boronate Affinity Interaction)

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12 pages, 1599 KiB

Open AccessArticle

CRISPR/Cas12a-Chemiluminescence Cascaded Bioassay for Amplification-Free and Sensitive Detection of Nucleic Acids

by Xiaotian Guan, Peizheng Wang, Yi Wang and Shuqing Sun

Biosensors 2025, 15(8), 479; https://doi.org/10.3390/bios15080479 - 24 Jul 2025

Abstract

The CRISPR/Cas system has attracted increasing attention in accurate nucleic acid detection. Herein, we reported a CRISPR/Cas12a-chemiluminescence cascaded bioassay (CCCB) for the amplification-free and sensitive detection of human papillomavirus type 16 (HPV-16) and parvovirus B19 (PB-19). A magnetic bead (MB)-linking single-stranded DNA (LssDNA)-alkaline [...] Read more.

The CRISPR/Cas system has attracted increasing attention in accurate nucleic acid detection. Herein, we reported a CRISPR/Cas12a-chemiluminescence cascaded bioassay (CCCB) for the amplification-free and sensitive detection of human papillomavirus type 16 (HPV-16) and parvovirus B19 (PB-19). A magnetic bead (MB)-linking single-stranded DNA (LssDNA)-alkaline phosphatase (ALP) complex was constructed as the core component of the bioassay. During the detection process, the single-stranded target DNA was captured and enriched by LssDNA and then activated the trans-cleavage activity of Cas12a. Due to the Cas12a-mediated cleavage of LssDNA, ALP was released from the MB, subsequently catalyzing the substrate to generate a chemiluminescence (CL) signal. Given the cascade combination of CRISPR/Cas12a with the CL technique, the limits of detection for HPV-16 and PB-19 DNA were determined as 0.14 pM and 0.37 pM, respectively, and the whole detection could be completed within 60 min. The practicality and reliability of the platform were validated through target-spiked clinical specimens, and the recovery rate was 93.4–103.5%. This dual-amplification strategy—operating without target pre-amplification—featured high specificity, low contamination risk, facile preparation, and robust stability. It provides a novel approach for sensitive nucleic acid detection, with the potential for rapid extension to the diagnosis of various infectious diseases. Full article

(This article belongs to the Special Issue Bioassays and Biosensors for Rapid Detection and Analysis (2nd Edition))

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