Biosensors

30 pages, 874 KB

Open AccessArticle

The Impact of Heat Stress on Dairy Cattle: Effects on Milk Quality, Rumination Behaviour, and Reticulorumen pH Response Using Machine Learning Models

by Karina Džermeikaitė, Justina Krištolaitytė, Dovilė Malašauskienė, Samanta Arlauskaitė, Akvilė Girdauskaitė and Ramūnas Antanaitis

Biosensors 2025, 15(9), 608; https://doi.org/10.3390/bios15090608 (registering DOI) - 15 Sep 2025

Abstract

Heat stress has a major impact on dairy cow health and productivity, especially during early lactation. Conventional heat stress monitoring methods frequently rely on single indicators, such as the temperature–humidity index (THI), which may miss subtle physiological and metabolic responses. This study presents [...] Read more.

Heat stress has a major impact on dairy cow health and productivity, especially during early lactation. Conventional heat stress monitoring methods frequently rely on single indicators, such as the temperature–humidity index (THI), which may miss subtle physiological and metabolic responses. This study presents a novel threshold-based classification framework that integrates biologically meaningful combinations of environmental, behavioural, and physiological variables to detect early-stage heat stress responses in dairy cows. Six composite heat stress conditions (C1–C6) were developed using real-time THI, milk temperature, reticulorumen pH, rumination time, milk lactose, and milk fat-to-protein ratio. The study applied and assessed five supervised machine learning models (Partial Least Squares Discriminant Analysis (PLS-DA), Support Vector Machine (SVM), Random Forest (RF0, Neural Network (NN), and an Ensemble approach) trained on daily datasets gathered from early-lactation dairy cows fitted with intraruminal boluses and monitored through milking parlour sensor systems. The dataset comprised approximately 36,000 matched records from 200 cows monitored over 60 days. The highest classification performance was observed for RF and NN models, particularly under C1 (THI > 73 and milk temperature > 38.6 °C) and C6 (THI > 74 and milk temperature > 38.7 °C), with AUC values exceeding 0.90. SHAP analysis revealed that milk temperature, THI, rumination time, and milk lactose were the most informative features across conditions. This integrative approach enhances precision livestock monitoring by enabling individualised heat stress risk classification well before clinical or production-level consequences emerge. Full article

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

17 pages, 1391 KB

Open AccessArticle

Gold Nanoparticle-Enhanced Recombinase Polymerase Amplification for Rapid Visual Detection of Mycobacterium tuberculosis

by Sukanya Saikaew, Sirikwan Sangboonruang, Rodjana Pongsararuk, Prapaporn Srilohasin, Bordin Butr-Indr, Sorasak Intorasoot, Ponrut Phunpae, Chayada Sitthidet Tharinjaroen, Surachet Arunothong, Wutthichai Panyasit, Angkana Chaiprasert, Khajornsak Tragoolpua and Usanee Wattananandkul

Biosensors 2025, 15(9), 607; https://doi.org/10.3390/bios15090607 (registering DOI) - 15 Sep 2025

Abstract

Tuberculosis (TB) remains a major global health challenge, particularly in resource-limited settings where access to rapid and reliable diagnostics is limited. Conventional diagnostic methods, such as smear microscopy and culture, are either time-consuming or lack adequate sensitivity. This study optimized recombinase polymerase amplification [...] Read more.

Tuberculosis (TB) remains a major global health challenge, particularly in resource-limited settings where access to rapid and reliable diagnostics is limited. Conventional diagnostic methods, such as smear microscopy and culture, are either time-consuming or lack adequate sensitivity. This study optimized recombinase polymerase amplification (RPA) using 16 primer combinations targeting IS6110 highly specific to the Mycobacterium tuberculosis complex (MTC). A novel naked-eye assay, TB-GoldDx, was developed by integrating RPA combined with gold nanoparticles (AuNPs), enabling equipment-free diagnostics. TB-GoldDx demonstrated a detection limit of 0.001 ng of MTB H37Rv DNA (~210 bacilli) per 25 µL reaction. Among 100 bacterial strains, it achieved 95.83% sensitivity and 100% specificity among 100 bacterial strains, comprising 72 MTB isolates and 28 nontuberculous bacterial species. In 140 sputum samples, the assay showed 81.43% sensitivity and 58.57% specificity versus acid-fast bacilli (AFB) smear microscopy, with sensitivity improving to 95.45% in high-load AFB 3+ specimens. Compared to a commercial line probe assay (LPA), TB-GoldDx exhibited slightly higher sensitivity (84.78% vs. 82.61%) but lower specificity (54.05% vs. 78.38%). Delivering rapid, visual results in under an hour, TB-GoldDx offers a low-cost, easily deployable solution for point-of-care tuberculosis detection, especially in underserved regions, reinforcing global End TB efforts. Full article

(This article belongs to the Section Biosensors and Healthcare)

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12 pages, 2384 KB

Open AccessArticle

Terahertz High-Sensitivity SPR Phase Biosensor Based on the Weyl Semimetals

by Yu Xie, Zean Shen, Mengjiao Ren, Mingming Zhang, Mingwei Guo and Leyong Jiang

Biosensors 2025, 15(9), 606; https://doi.org/10.3390/bios15090606 - 15 Sep 2025

Abstract

Optical biosensors play a crucial role in the field of biological detection by converting biological signals into optical signals for detection. Among them, Surface Plasmon Resonance (SPR) optical biosensors have become a research hotspot in this field due to their significant advantage of [...] Read more.

Optical biosensors play a crucial role in the field of biological detection by converting biological signals into optical signals for detection. Among them, Surface Plasmon Resonance (SPR) optical biosensors have become a research hotspot in this field due to their significant advantage of high sensitivity. Weyl Semimetals (WSMs), as a type of three-dimensional topological material with unique electronic structures and other properties, exhibit potential applications in the field of SPR sensing. Against this background, we designed a terahertz (THz) high-sensitivity SPR phase biosensor with a KR structure based on WSMs. When applied in gas sensing scenarios, the phase detection sensitivity of this sensor can reach 22,402

°

/RIU, showing a significant improvement compared to traditional SPR biosensors. Moreover, we found that the Weyl node separation distance and twist angle of WSMs have obvious effects on sensitivity regulation. Additionally, we optimized the sensitivity and structural parameters of this structure using a neural network-based deep learning algorithm. We expect that this proposed scheme can provide a feasible reference for the field of biological sensing. Full article

(This article belongs to the Special Issue New Progress in Optical Fiber-Based Biosensors—2nd Edition)

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20 pages, 3511 KB

Open AccessCommunication

An Aptamer-Based gFET-Sensor for Specific Quantification of Gene Therapeutic Human Adenovirus Type 5

by Runliu Li, Ann-Kathrin Kissmann, Hu Xing, Roger Hasler, Christoph Kleber, Wolfgang Knoll, Hannes Schmietendorf, Tatjana Engler, Lea Krutzke, Stefan Kochanek and Frank Rosenau

Biosensors 2025, 15(9), 605; https://doi.org/10.3390/bios15090605 - 14 Sep 2025

Abstract

The combination of rGO-FETs (reduced Graphene Oxide Field-Effect Transistors) and DNA-oligonucleotide aptamers to sense analytes has been shown to be a promising technological approach, achieving high sensitivity and selectivity. With human adenovirus type 5 (HAdV-5) particles as the target, we here demonstrate the [...] Read more.

The combination of rGO-FETs (reduced Graphene Oxide Field-Effect Transistors) and DNA-oligonucleotide aptamers to sense analytes has been shown to be a promising technological approach, achieving high sensitivity and selectivity. With human adenovirus type 5 (HAdV-5) particles as the target, we here demonstrate the application of the aptamer/FET combination for detection of this medically and biotechnologically relevant viral vector. A focused anti-HAdV-5 aptamer library was evolved in a nine-round SELEX process, allowing for the specific fluorescent labeling of HAdV-5 and related subtypes. Moreover, this library was already sufficient to serve as the binding entity on a gFET sensor for sensitive quantification of the virus particles. Adenoviruses have been widely used as gene delivery vectors for gene therapy and genetic vaccination. The use of adenoviral vectors within the vaccination campaign against COVID-19 emphasized the need for robust biotechnological production processes, which additionally require sensitive product formation monitoring. We believe that these type of gFET-based aptasensors can serve as the technological monitoring basis in virus production processes in the near future. Full article

(This article belongs to the Special Issue Transistor-Based Biosensors and Their Applications)

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20 pages, 2623 KB

Open AccessArticle

Construction of an Electrochemical Impedance Spectroscopy Matching Method Based on Adaptive Multi-Error Driving and Application Testing for Biofilm Impedance Verification

by Hanyang Bao, Fan Yu, Peiyan Dai, Boyu Guo and Ying Xu

Biosensors 2025, 15(9), 604; https://doi.org/10.3390/bios15090604 - 12 Sep 2025

Viewed by 79

Abstract

Electrochemical impedance spectroscopy (EIS) is a technique used to analyze the kinetics and interfacial processes of electrochemical systems. The selection of an appropriate equivalent circuit model for EIS interpretation was traditionally reliant on expert experience, rendering the process subjective and prone to error. [...] Read more.

Electrochemical impedance spectroscopy (EIS) is a technique used to analyze the kinetics and interfacial processes of electrochemical systems. The selection of an appropriate equivalent circuit model for EIS interpretation was traditionally reliant on expert experience, rendering the process subjective and prone to error. To address these limitations, an automated framework for both model selection and parameter estimation was proposed. The methodology was structured such that initial model screening was performed by a global heuristic search algorithm, adaptive optimization was guided by an integrated XGBoost-based error feedback mechanism, and precise parameter estimation was achieved using a Differential Evolution–Levenberg–Marquardt (DE-LM) algorithm. When evaluated on a purpose-built dataset comprising 4.8 × 10⁵ spectra across diverse circuit and biofilm scenarios, a model classification accuracy of 96.32% was achieved, and a 72.3% reduction in parameter estimation error was recorded. The practical utility of the method was validated through the quantitative analysis of bovine serum albumin–Clenbuterol hydrochloride (BSA-CLB), wherein an accuracy of 95.2% was demonstrated and a strong linear correlation with target concentration (R² = 0.999) was found. Through this approach, the limitations of traditional black-box models were mitigated by resolving the physical meaning of parameters. Consequently, the automated and quantitative monitoring of processes such as biofilm formation was facilitated, enabling the efficient evaluation of antimicrobial drugs or anti-fouling coatings. Full article

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

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28 pages, 4943 KB

Open AccessReview

From Biomarkers to Biosensors: Modern Approaches for the Detection of Matrix Metalloproteinases (MMPs)

by Raja Chinnappan, Lohit Ramachandran, Isha Uttam, Marimuthu Citartan, Nidambur Vasudev Ballal and Naresh Kumar Mani

Biosensors 2025, 15(9), 603; https://doi.org/10.3390/bios15090603 - 12 Sep 2025

Viewed by 157

Abstract

Matrix metalloproteinases (MMPs) are a class of extracellular Zn²⁺ peptidases involved in various physiological and pathological processes. These enzymes serve as excellent biomarkers for diagnosing various diseases, including cancer and periodontitis, to name a few. MMP levels also serve as a prognostic [...] Read more.

Matrix metalloproteinases (MMPs) are a class of extracellular Zn²⁺ peptidases involved in various physiological and pathological processes. These enzymes serve as excellent biomarkers for diagnosing various diseases, including cancer and periodontitis, to name a few. MMP levels also serve as a prognostic marker, which helps determine how much the disease has progressed. However, the current methods used to detect MMPs need a large sample volume, carry a high cost, and are not widely accessible to the public due to these challenges. Biosensing techniques tackle these problems by providing an efficient, cost-effective sensor with great sensitivity. This review provides a comprehensive overview of the latest developments and advancements in detecting MMPs using biosensors that employ various detection mechanisms such as electrochemical, colorimetric, and fluorescence methods. Furthermore, we have discussed the challenges and prospects of using MMPs as diagnostic tools. Full article

(This article belongs to the Special Issue Lighting Up Single-Molecule Biosensors and Bioimaging: Now and the Decade to Come)

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14 pages, 7832 KB

Open AccessArticle

Self-Adaptive Polymer Fabry–Pérot Thermometer for High-Sensitivity and Wide-Linear-Range Sensing

by Yifan Cheng, Maolin Yu, Junjie Liu, Yingling Tan and Jinhui Chen

Biosensors 2025, 15(9), 602; https://doi.org/10.3390/bios15090602 - 12 Sep 2025

Viewed by 128

Abstract

Fiber-optic temperature sensors with advantages such as simplicity, low cost, and high sensitivity have attracted increasing attention. In this work, we propose a self-adaptive polymer Fabry–Pérot interferometer (PFPI) sensor for ultrasensitive and wide-linear-range thermal sensing. This design achieves a temperature sensitivity of 0.95 [...] Read more.

Fiber-optic temperature sensors with advantages such as simplicity, low cost, and high sensitivity have attracted increasing attention. In this work, we propose a self-adaptive polymer Fabry–Pérot interferometer (PFPI) sensor for ultrasensitive and wide-linear-range thermal sensing. This design achieves a temperature sensitivity of 0.95 nm/°C, representing an enhancement of two orders of magnitude compared to conventional fiber Bragg gratings. To address the challenge of spectral shifts exceeding the free spectral range due to the high sensitivity, a local cross-correlation algorithm is introduced for accurate wavelength tracking. We demonstrate ultrahigh-resolution (0.025 °C) scanning thermal field imaging and sensitive human physiological monitoring, including precise body temperature and respiratory rate detection. These results highlight the dual capability of our PFPI sensor for both microscopic thermal mapping and non-invasive healthcare applications. Full article

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

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19 pages, 5463 KB

Open AccessArticle

PEI-Fe₃O₄/PTA-AuNPs Hybrid System for Rapid DNA Extraction and Colorimetric LAMP Detection of E. faecium

by Muniyandi Maruthupandi, Haang Seok Choi and Nae Yoon Lee

Biosensors 2025, 15(9), 601; https://doi.org/10.3390/bios15090601 - 12 Sep 2025

Viewed by 215

Abstract

This study introduces a novel nucleic acid testing (NAT) protocol that integrates rapid deoxyribonucleic acid (DNA) extraction, isothermal amplification, and visual detection to enable efficient analysis of opportunistic pathogens. Polyethylenimine-functionalized iron oxide (PEI-Fe₃O₄) nanoparticles were prepared by combining PEI, [...] Read more.

This study introduces a novel nucleic acid testing (NAT) protocol that integrates rapid deoxyribonucleic acid (DNA) extraction, isothermal amplification, and visual detection to enable efficient analysis of opportunistic pathogens. Polyethylenimine-functionalized iron oxide (PEI-Fe₃O₄) nanoparticles were prepared by combining PEI, acting as a stabilizing agent, with iron salt, which was utilized as the metal ion precursor by the ultrasonication-assisted co-precipitation method, and characterized for structural, optical, and magnetic properties. PEI-Fe₃O₄ exhibited cationic and anionic behavior in response to pH variations, enhancing adaptability for DNA binding and release. PEI-Fe₃O₄ enabled efficient extraction of E. faecium DNA within 10 min at 40 °C, yielding 17.4 ng/µL and achieving an extraction efficiency of ~59% compared to a commercial kit (29.5 ng/µL). The extracted DNA was efficiently amplified by loop-mediated isothermal amplification (LAMP) at 65 °C for 45 min. Pyrogallol-rich poly(tannic acid)-stabilized gold nanoparticles (PTA-AuNPs) served as colorimetric probes for direct visual detection of the DNA amplified using LAMP. The magnetic-nanogold (PEI-Fe₃O₄/PTA-AuNPs) hybrid system achieved a limit of quantification of 1 fg/µL. To facilitate field deployment, smartphone-based RGB analysis enabled quantitative and equipment-free readouts. Overall, the PEI-Fe₃O₄/PTA-AuNPs hybrid system used in NAT offers a rapid, cost-effective, and portable solution for DNA detection, making the system suitable for microbial monitoring. Full article

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

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26 pages, 5753 KB

Open AccessReview

Metal–Phenolic Networks for Sensing Applications

by Ning Xia, Sirui Liang, Dehua Deng, Yong Chang and Xinyao Yi

Biosensors 2025, 15(9), 600; https://doi.org/10.3390/bios15090600 - 11 Sep 2025

Viewed by 278

Abstract

The preparation of new inorganic–organic hybrid materials is beneficial for the development of powerful sensing methods and technologies. Polyphenols, a type of organic molecule containing phenolic hydroxyl groups, are widely present in natural plants and have beneficial effects on human health. Metal ions [...] Read more.

The preparation of new inorganic–organic hybrid materials is beneficial for the development of powerful sensing methods and technologies. Polyphenols, a type of organic molecule containing phenolic hydroxyl groups, are widely present in natural plants and have beneficial effects on human health. Metal ions are ubiquitous in nature and play an important role in the development of inorganic–organic hybrid materials. Metal–phenolic networks (MPNs) are formed by the self-assembly of metal ions and polyphenols through dynamic coordination bonds. Due to their mild synthesis conditions, facilely engineered functionalities, and multiple modification strategies, MPNs have become potential platforms for sensing applications. Timely understanding of the function and application of MPNs in sensing fields will facilitate the development of novel chemical and biological sensors and devices. This article summarizes the typical preparation methods and excellent advantages of MPNs and focuses on their latest achievements in sensing applications. We highlight representative MPN-based sensing examples, including the direct detection of small molecules and biological species, immunoassays, bioimaging, and wearable devices. Finally, the prospects and future directions of MPNs in sensing fields are addressed. Full article

(This article belongs to the Special Issue Biosensors Based on Self-Assembly and Molecular Recognition—2nd Edition)

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20 pages, 6524 KB

Open AccessArticle

Foreign Body Reaction to Neural Implants: A Comparative Study of Polymer Toxicity and Tissue Response

by Ciara Makievskaya, Anna Brezgunova, Nadezda Andrianova, Evgeny Kelm, Maria Solovyova, Gelena Naumova, Alina Zeinalova, Olga Gancharova, Tatiana Bushkova, Daniil Kozlov, Valery Putlayev, Pavel Evdokimov, Alexander Petrov, Mikhail Lebedev, Egor Plotnikov and Vasily Popkov

Biosensors 2025, 15(9), 599; https://doi.org/10.3390/bios15090599 - 11 Sep 2025

Viewed by 260

Abstract

This study investigated the toxicity of ten polymer materials intended for the development of invasive neural interfaces improving the treatment of neurological diseases. Most of the materials for neural implants can cause traumatization of the surrounding tissue, inflammation, and foreign body reaction. In [...] Read more.

This study investigated the toxicity of ten polymer materials intended for the development of invasive neural interfaces improving the treatment of neurological diseases. Most of the materials for neural implants can cause traumatization of the surrounding tissue, inflammation, and foreign body reaction. In this study, in vitro and in vivo toxicity assessment was performed for nylon 618 (NY), polycaprolactone (PCL), polyethylene glycol diacrylate (PEGDA), polydimethylsiloxane (PDMS), polyethylene terephthalate (PET), polylactide (PLA), thermoplastic polyurethane (TPU), polypropylene (PP), polyethylene terephthalate glycol (PET-G), and polyimide (PI). The biocompatibility of these ten materials was assessed based on cell adhesion, growth and cytotoxicity on neural (PC-12) and fibroblast (NRK-49F) cultures. Furthermore, brain tissue responses to the implanted phantom scaffolds were analyzed in rats. According to these measurements, PI showed the highest compatibility for both cell types. PEGDA exhibited cytotoxic effects, low cell adhesion and the strongest foreign body reaction, including fibrosis and multinucleated cell formation. The other polymers showed lower pathological responses which makes them potentially usable for neural interfacing. We conclude that PEGDA appears to be unsuitable for long-term use due to adverse tissue and cellular reactions, whereas PI, PLA, PDMS and TPU hold promise as materials for safe and effective neural interface applications. Full article

(This article belongs to the Special Issue Implantable, Wireless Biosensors and Biodevices for Neuroscience Research, 2nd Edition)

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19 pages, 7792 KB

Open AccessArticle

Evaluation of Fluorescence Detection Algorithms for Efficient ROI Setting in Low-Cost Real-Time PCR Systems

by Seul-Bit-Na Koo, Ji-Soo Hwang, Chan-Young Park and Deuk-Ju Lee

Biosensors 2025, 15(9), 598; https://doi.org/10.3390/bios15090598 - 10 Sep 2025

Viewed by 169

Abstract

This study proposes a region of interest (ROI) setting method to improve the accuracy and efficiency of fluorescence detection in a compact real-time multiplex fluorescence PCR system. Conventional commercial real-time PCR systems are limited in point-of-care (POC) environments due to their high cost [...] Read more.

This study proposes a region of interest (ROI) setting method to improve the accuracy and efficiency of fluorescence detection in a compact real-time multiplex fluorescence PCR system. Conventional commercial real-time PCR systems are limited in point-of-care (POC) environments due to their high cost and complex optical structures. To address this issue, we developed a low-cost, compact system using an open-platform camera and a Fresnel lens. However, in such a simply structured system, variations between the wells of the polymerase chain reaction (PCR) plate may affect the accuracy of fluorescence detection. In this study, after capturing images with a CMOS camera, we propose two ROI image processing algorithms. The proposed algorithms reliably extract fluorescence signals and compare ROI deviations caused by variations between wells to determine whether physical correction is necessary. To validate the system, we performed comparative analysis of real-time DNA amplification images and fluorescence dye images collected over multiple periods. Based on evaluations using manual detection as a reference, it was confirmed that even a simple algorithm can achieve stable fluorescence detection while minimizing ROI distortion. This study presents an efficient method for enhancing the accuracy of quantitative fluorescence analysis in small PCR systems and is expected to contribute to improving the performance of point-of-care diagnostics, thereby increasing accessibility to on-site diagnostics in the future. Full article

(This article belongs to the Special Issue Recent Advances and Applications of Multiplexed Analysis and Multiplexed Nanobiosensors)

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11 pages, 2701 KB

Open AccessArticle

Simulation-Based Performance Assessment of Bulk Junctionless FET with Asymmetric Source/Drain for Ultrasensitive Detection of Biomolecules

by Jeongmin Son, M. Meyyappan and Kihyun Kim

Biosensors 2025, 15(9), 597; https://doi.org/10.3390/bios15090597 - 10 Sep 2025

Viewed by 170

Abstract

Bio field-effect transistors (BioFETs) have attracted attention for their ability to rapidly detect physiological data with a simple structure. While conventional BioFETs offer high sensitivity, they often require reference electrodes or involve complex fabrication processes. A recently proposed bulk junctionless BioFET (Bulk JL-BioFET) [...] Read more.

Bio field-effect transistors (BioFETs) have attracted attention for their ability to rapidly detect physiological data with a simple structure. While conventional BioFETs offer high sensitivity, they often require reference electrodes or involve complex fabrication processes. A recently proposed bulk junctionless BioFET (Bulk JL-BioFET) features a simple fabrication process to address these issues. This structure utilizes a depletion region formed by a p-n junction, as the active layer is directly in contact with a substrate of the opposite type. As a result, the device can operate effectively with only two terminals—drain and source—without the need for a reference electrode. In this study, we propose a novel Bulk JL-BioFET, incorporating a doped field stop layer and an asymmetric source/drain structure, and verify its performance through simulations. The doped field stop layer blocks the electric field expansion, enhancing channel modulation, while the asymmetric source/drain structure promotes electron injection, reducing the on-off swing voltage and turn-on voltage. This improves the electrical performance, enabling lower power consumption and higher sensitivity. Simulation results show that the combination of these two novel features results in a sensitivity increase of approximately 30-fold. Moreover, high sensitivity was observed below the turn-on voltage region for all the structures when analyzing the sensitivity with overdrive voltage, identifying the optimal operating conditions. This study suggests that the combination of the doped field stop layer and asymmetric source/drain structure is an effective design strategy to maximize the sensing performance of BioFETs while minimizing power consumption. Full article

(This article belongs to the Special Issue Transistor-Based Biosensors and Their Applications)

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14 pages, 4226 KB

Open AccessArticle

Pathogen-on-a-Chip: Impedance-Based Detection of Biofilm Formation of Staphylococcus aureus and Staphylococcus epidermidis

by Bengisu Yöney, Radka Obořilová, Karel Lacina, Zdeněk Farka and Petr Skládal

Biosensors 2025, 15(9), 596; https://doi.org/10.3390/bios15090596 - 10 Sep 2025

Viewed by 171

Abstract

Bacterial biofilms are complex microbial communities that contribute to the pathogenesis of chronic infections. Therefore, it is crucial to detect biofilm-associated infections in early stages as their delayed treatment becomes more complicated. Herein, we describe a label-free electrochemical impedance spectroscopy (EIS) method for [...] Read more.

Bacterial biofilms are complex microbial communities that contribute to the pathogenesis of chronic infections. Therefore, it is crucial to detect biofilm-associated infections in early stages as their delayed treatment becomes more complicated. Herein, we describe a label-free electrochemical impedance spectroscopy (EIS) method for detecting biofilm formation by Staphylococcus aureus and Staphylococcus epidermidis. Printed circuit board-based biamperometric gold electrodes were modified with poly-L-lysine to enhance bacterial attachment to the sensor surface. Formation and inhibition of biofilms were evaluated based on changes in charge transfer resistance (R_ct). The control R_ct value increased by ~90 kΩ for S. epidermidis biofilm and by ~60 kΩ for S. aureus biofilms. Antibiotic-treated samples exhibited similar values to those using the control. In addition, biofilm formation was evaluated through optical microscopy using safranin staining, and the micrographs suggest significant biomass on the electrodes, whereas the control appeared clear. Atomic force microscopy was used to visualize the biofilm on the electrode surface, obtain cross-sectional profiles, and evaluate its roughness. The roughness parameters indicate that S. aureus forms a rougher biofilm than S. epidermidis, while S. epidermidis forms a more compact biofilm. These findings suggest that the optimized EIS-based method effectively monitors changes related to biofilms and serves as a promising tool for evaluation of new anti-biofilm agents, such as antibiotics, phages or antibodies. Full article

(This article belongs to the Special Issue Electrochemical (Bio)Sensors as Promising Analytical Tools in the Analysis of Soils, Plants and Environmental Monitoring)

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23 pages, 1211 KB

Open AccessReview

Advancements and Applications of Split Technology in CRISPR/Cas12a: Transforming Molecular Diagnostics and Biosensing

by Saikarthik Jayakumar, Srinivasan Vengadassalapathy, Santhosh Venkadassalapathy, Sheela Durairajan, Radha Vijayaraj and Lakshmanan Govindan

Biosensors 2025, 15(9), 595; https://doi.org/10.3390/bios15090595 - 10 Sep 2025

Viewed by 244

Abstract

The rapid evolution of CRISPR technology has revolutionized molecular biology, and among the various systems, CRISPR/Cas12a stands out for its high specificity and efficient collateral cleavage activity. This review article focuses on the recent advancements and applications of split technology within the CRISPR/Cas12a [...] Read more.

The rapid evolution of CRISPR technology has revolutionized molecular biology, and among the various systems, CRISPR/Cas12a stands out for its high specificity and efficient collateral cleavage activity. This review article focuses on the recent advancements and applications of split technology within the CRISPR/Cas12a framework, highlighting its transformative role in molecular diagnostics and biosensing. Split technology innovatively divides functional nucleic acid components into modular segments that are activated by specific targets, significantly enhancing the specificity and sensitivity of biosensors. This design addresses the inherent limitations of traditional sensor systems, enabling the direct detection of ultrashort nucleic acids and improved discrimination of single-nucleotide variants, thereby facilitating the simultaneous detection of multiple biomolecules. The versatility of split-enabled biosensors extends beyond genetic testing, making them valuable tools in diagnostics, therapeutics, and environmental science. Despite challenges such as crRNA degradation and reassembly kinetics, ongoing research and engineering solutions continue to enhance the stability and performance of these systems. This review synthesizes the foundational principles, recent advancements, and potential applications of split technology while also identifying challenges and opportunities for future exploration. Ultimately, our insights provide a comprehensive resource to leverage the full potential of CRISPR/Cas12a-based split technology in advancing biosensing methodologies and clinical applications. Full article

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

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15 pages, 613 KB

Open AccessArticle

Whole-Cell Bioreporter-Based Assay for Detecting Fungal-Derived β-Lactamase Inhibitors

by Raz Benou, Robert S. Marks, Alex Sivan, Esti Kramarsky-Winter, Karina Golberg and Ariel Kushmaro

Biosensors 2025, 15(9), 594; https://doi.org/10.3390/bios15090594 - 9 Sep 2025

Viewed by 218

Abstract

β-lactams are an important family of antibiotics that are prone to undergo resistance inhibition though the production of β-lactamases by some microorganisms. To combat this resistance and preserve the efficacy of β-lactam antibiotics, we developed a strategy for the discovery of such β-lactamase [...] Read more.

β-lactams are an important family of antibiotics that are prone to undergo resistance inhibition though the production of β-lactamases by some microorganisms. To combat this resistance and preserve the efficacy of β-lactam antibiotics, we developed a strategy for the discovery of such β-lactamase inhibitors. When combined with β-lactams, these inhibitors allow the antibiotics to be effective and prevent resistance. To date, the development of such combinatory drugs is limited due to the complexity of screening for new β-lactamase inhibitors. Therefore, to facilitate this development, it was essential to find sensitive assays to effectively screen for lactamase inhibitory compounds. To this end, a novel bioassay utilizing bioluminescent indicator bacteria as bioreporters was developed. The assay was first optimized using commercial antibiotics together with known β-lactamase inhibitors. Using this bioassay, we then screened for novel natural β-lactamase inhibitors derived from coral-associated fungi. We showed that the fungus Penicillium spinulosum, originating from the coral Pocillopora sp. from the Gulf of Aqaba Eilat, produced compounds with anti-β-lactamase activity. We further demonstrated that the bioreporter bacteria used here responded to the combined antibiotics and β-lactamase inhibitors in a concentration-dependent manner, indicating their usefulness for β-lactamase-inhibiting compound discovery. Future structural identification will promote the validation of this assay’s usefulness. Full article

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

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28 pages, 6575 KB

Open AccessReview

Role of Polymeric Stabilizing Agents as a Molecular Spacer in Gold Nanoparticle-Mediated FRET-Based Biosensing

by Atul Kumar Tiwari and Roger J. Narayan

Biosensors 2025, 15(9), 593; https://doi.org/10.3390/bios15090593 - 9 Sep 2025

Viewed by 338

Abstract

In FRET-based sensing, the interaction between the analytes and metal nanoparticles is significantly regulated by the physicochemical characteristics of the nanoparticles, such as their shape, size, zeta potential, surface-linked ligands, doping, pH of the medium, particle surface roughness, and lattice structure (atomic arrangements). [...] Read more.

In FRET-based sensing, the interaction between the analytes and metal nanoparticles is significantly regulated by the physicochemical characteristics of the nanoparticles, such as their shape, size, zeta potential, surface-linked ligands, doping, pH of the medium, particle surface roughness, and lattice structure (atomic arrangements). During the synthesis process, to avert the aggregation of gold nanoparticles (AuNPs), synthetic polymers (including polyethylene glycol, polyethyleneimine, and poly-N-vinylpyrrolidone) and natural polymers (such as chitosan, starch, gellan, welan, and κ-carrageenan) are frequently employed for stabilization. This stabilization is accomplished through mechanisms such as steric repulsion and electrostatic stabilization, which form a protective layer around AuNPs. These stabilizing polymers act as molecular spacers in nanoparticle-based FRET sensing, enabling the precise regulation of the molecular distance between the acceptor and donor fluorophore molecules. This regulation enhances the efficiency and sensitivity of FRET assays. By modifying the length and flexibility of the spacer polymer, researchers can adjust the spacing between fluorophores, ensuring effective energy transfer and the accurate detection of target molecules. However, there is a limited understanding of the role and broad application of these molecular spacers in nanoparticle-mediated FRET-based sensing of various analytes. Consequently, this review explores different fundamental aspects of FRET, polymeric stabilization of gold nanoparticles, and various polymeric spacers in FRET-based sensing, along with the recent advancements and challenges associated with this approach. Full article

(This article belongs to the Special Issue Advances in Portable and Wearable Sensing Systems for Biochemical Monitoring)

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19 pages, 2679 KB

Open AccessArticle

Development of a Multiplex Lateral Flow Immunoassay for the Detection of Antibiotics in Milk Utilizing Lyophilized Gold Nanoparticle Conjugates

by Ivan V. Maksin, Azhar Kuandykova, Darya I. Polyakova, Viktoriia A. Kesareva, Timofei A. Luzyanin, Vladislav S. Ivanov, Evgeniia I. Simonova, German A. Khunteev and Yuliya G. Kirillova

Biosensors 2025, 15(9), 592; https://doi.org/10.3390/bios15090592 - 9 Sep 2025

Viewed by 335

Abstract

Lateral flow immunoassays (LFAs) are widely recognized as a powerful and versatile analytical platform. Nevertheless, the development of multiplex formats remains a distinct challenge. The aim of this study was to develop a multiplex LFA using gold nanoparticles (GNPs) as a label, selected [...] Read more.

Lateral flow immunoassays (LFAs) are widely recognized as a powerful and versatile analytical platform. Nevertheless, the development of multiplex formats remains a distinct challenge. The aim of this study was to develop a multiplex LFA using gold nanoparticles (GNPs) as a label, selected for their ease of synthesis and functionalization with biomolecules. We provide practical recommendations regarding protein–hapten synthesis, membrane selection, application buffer composition, and methods to improve the long-term stability of the freeze-dried gold conjugate. The developed assay shows good tolerance to high-fat milk, stability at elevated temperatures, and promising sensitivity, with visual detection limits of 4–100 ng/mL for

β

-lactams, 1–10 ng/mL for tetracyclines, 50 ng/mL for streptomycin, and 0.3 ng/mL for chloramphenicol. Full article

(This article belongs to the Special Issue Immunosensors: Design and Applications)

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18 pages, 3215 KB

Open AccessReview

Review of Pulsation Signal Detection and Applications in Dynamic Photoacoustic Imaging

by Wenhan Zheng, Chuqin Huang and Jun Xia

Biosensors 2025, 15(9), 591; https://doi.org/10.3390/bios15090591 - 8 Sep 2025

Viewed by 248

Abstract

Pulsatile signal detection plays an important role in monitoring various physiological parameters, primarily heart rate and blood oxygen saturation. Their applications range from clinical settings to personal health and wellness monitoring. PPG (photoplethysmography) can provide non-invasive optical measurements to detect blood volume changes [...] Read more.

Pulsatile signal detection plays an important role in monitoring various physiological parameters, primarily heart rate and blood oxygen saturation. Their applications range from clinical settings to personal health and wellness monitoring. PPG (photoplethysmography) can provide non-invasive optical measurements to detect blood volume changes in peripheral tissues. Yet, it suffers from low spatial resolution to precisely detect the pulsatile signal originating over 2 mm in human tissue. Ultrasound (US) provides a deep detectable range compared to the pure optical method. However, its low contrast to red blood cells and cluster artifacts makes it only detect the indirect pulsation from the surrounding tissue of blood vessels. Recent advances in PA imaging show its capability to precisely measure pulsatile signals originating from blood vessels in deep regions (over 10 mm) and its potential to accurately record blood oxygen saturation with high spatial and temporal resolution. This review article summarizes studies on photoacoustic (PA) pulsatile signal monitoring, highlights the technical advances, and compares it against optical and ultrasonic approaches. Full article

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

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44 pages, 8360 KB

Open AccessSystematic Review

Natural Iron Oxide Nanoparticles Produced by Aquatic Magnetotactic Bacteria as Ideal Nanozymes for Nano-Guided Biosensing Platforms—A Systematic Review

by Natalia Lorela Paul, Catalin Ovidiu Popa and Rodica Elena Ionescu

Biosensors 2025, 15(9), 590; https://doi.org/10.3390/bios15090590 - 8 Sep 2025

Viewed by 299

Abstract

In response to the ongoing challenges associated with natural enzymes, their high production costs, low stability and limited functionality; nanozymes have rapidly emerged as versatile alternative. Such nanocatalysts, based on nanomaterials and nanostructures, offer remarkable tunability of physicochemical properties and excellent durability, and [...] Read more.

In response to the ongoing challenges associated with natural enzymes, their high production costs, low stability and limited functionality; nanozymes have rapidly emerged as versatile alternative. Such nanocatalysts, based on nanomaterials and nanostructures, offer remarkable tunability of physicochemical properties and excellent durability, and adapt themselves effectively to the requirements of modern biotechnological applications. This review article aims to provide a comprehensive overview of recent advances in the use of naturally occurring iron oxide nanoparticles, produced by magnetotactic bacteria, and to highlight their emerging role as key elements in the development of the new generation of nano-guided biosensors. It provides a comprehensive and systematic analysis of publications in the Web of Science database between 2022 and August 2025, conducted in accordance with PRISMA guidelines. The aim was to assess the current state of the art and identify knowledge gaps in the exploration and application of magnetotactic bacteria as natural and sustainable sources in the design of next-generation biosensors. The natural nanoparticles, formed through biological processes, represent a unique and sustainable alternative to synthetic nanoparticles, offering naturally mimetic enzymatic activity, high biocompatibility, and exceptional stability. This approach opens up revolutionary perspectives in the field of biosensors, proposing a new class of functional materials, iron nanoparticles of biological origin, capable of fundamentally changing the performance, sustainability and reliability of future nanoenzymatic sensing platforms. Full article

(This article belongs to the Special Issue Cutting-Edge Nanozyme Biosensing Strategies for Biomedical and Environmental Applications)

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37 pages, 2546 KB

Open AccessReview

POC Sensor Systems and Artificial Intelligence—Where We Are Now and Where We Are Going?

by Prashanthi Kovur, Krishna M. Kovur, Dorsa Yahya Rayat and David S. Wishart

Biosensors 2025, 15(9), 589; https://doi.org/10.3390/bios15090589 - 8 Sep 2025

Viewed by 362

Abstract

Integration of machine learning (ML) and artificial intelligence (AI) into point-of-care (POC) sensor systems represents a transformative advancement in healthcare. This integration enables sophisticated data analysis and real-time decision-making in emergency and intensive care settings. AI and ML algorithms can process complex biomedical [...] Read more.

Integration of machine learning (ML) and artificial intelligence (AI) into point-of-care (POC) sensor systems represents a transformative advancement in healthcare. This integration enables sophisticated data analysis and real-time decision-making in emergency and intensive care settings. AI and ML algorithms can process complex biomedical data, improve diagnostic accuracy, and enable early disease detection for better patient outcomes. Predictive analytics in POC devices supports proactive healthcare by analyzing data to forecast health issues and facilitating early intervention and personalized treatment. This review covers the key areas of ML and AI integration in POC devices, including data analysis, pattern recognition, real-time decision support, predictive analytics, personalization, automation, and workflow optimization. Examples of current POC devices that use ML and AI include AI-powered blood glucose monitors, portable imaging devices, wearable cardiac monitors, AI-enhanced infectious disease detection, and smart wound care sensors are also discussed. The review further explores new directions for POC sensors and ML integration, including mental health monitoring, nutritional monitoring, metabolic health tracking, and decentralized clinical trials (DCTs). We also examined the impact of integrating ML and AI into POC devices on healthcare accessibility, efficiency, and patient outcomes. Full article

(This article belongs to the Special Issue Trends in Development of Biosensors for Disease Diagnosis, Treatment and Management—2nd Edition)

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17 pages, 2819 KB

Open AccessArticle

Robust Pt/Au Composite Nanostructures for Abiotic Glucose Sensing

by Asghar Niyazi, Ashley Linden and Mirella Di Lorenzo

Biosensors 2025, 15(9), 588; https://doi.org/10.3390/bios15090588 - 8 Sep 2025

Viewed by 278

Abstract

Effective glucose monitoring is paramount for patients with diabetes to effectively manage their condition and prevent health complications. Electrochemical sensors for glucose monitoring have key advantages over other systems, including cost-effectiveness, miniaturisation and portability, enabling the design of compact and wearable devices. Typically, [...] Read more.

Effective glucose monitoring is paramount for patients with diabetes to effectively manage their condition and prevent health complications. Electrochemical sensors for glucose monitoring have key advantages over other systems, including cost-effectiveness, miniaturisation and portability, enabling the design of compact and wearable devices. Typically, enzymes are used in these sensors, with the limitations of poor stability and high cost. In alternative, this study reports the development of a gold and platinum composite nanostructured electrode and its testing as an abiotic (enzyme-free) electrocatalyst for glucose oxidation. The electrode consists of a film of highly porous gold electrodeposited onto gold-plated electrodes on a printed circuit board (PCB), which is coated with polyaniline decorated with platinum nanoparticles. The resulting nanocomposite structure shows a sensitivity towards glucose as high as 95.12 ± 2.54 µA mM⁻¹ cm⁻², nearly twice that of the highly porous gold electrodes, and excellent stability in synthetic interstitial fluid over extended testing, thus demonstrating robustness. Accordingly, this study lays the groundwork for the next generation of durable, selective, and affordable abiotic glucose biosensors. Full article

(This article belongs to the Special Issue Biosensor Nanoengineering: Design, Operation and Implementation—2nd Edition)

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50 pages, 4023 KB

Open AccessReview

Organic Bioelectronics: Diversity of Electronics Along with Biosciences

by Syed Abdul Moiz, Mohammed Saleh Alshaikh and Ahmed N. M. Alahmadi

Biosensors 2025, 15(9), 587; https://doi.org/10.3390/bios15090587 - 7 Sep 2025

Viewed by 599

Abstract

This review article provides an introductory overview of organic bioelectronics, focusing on the creation of electrical devices that use specialized carbon-based semiconducting materials to interact successfully with biological processes. These organic materials demonstrate flexibility, biocompatibility, and the capacity to carry both electrical and [...] Read more.

This review article provides an introductory overview of organic bioelectronics, focusing on the creation of electrical devices that use specialized carbon-based semiconducting materials to interact successfully with biological processes. These organic materials demonstrate flexibility, biocompatibility, and the capacity to carry both electrical and ionic impulses, making them an ideal choice for connecting human tissue with electronic technology. The review study examines diverse materials, such as the conductive polymers Poly(3,4-ethylenedioxythiophene) polystyrene sulfonate (PEDOT:PSS) and Polyaniline (PANI), along with critical devices like organic electrochemical transistors (OECTs), which are exceptionally efficient for sensitive biosensing applications. Significant applications include implanted neural interfaces for the brain and nerves, wearable health monitoring, tissue engineering scaffolds that facilitate tissue repair, and sophisticated drug delivery systems. The review acknowledges current challenges, including long-term stability and safety, while envisioning a future where these technologies revolutionize healthcare, human–machine interaction, and environmental monitoring via continuous multidisciplinary innovation. Full article

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

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40 pages, 3625 KB

Open AccessReview

Graphene-Based Biosensors: Enabling the Next Generation of Diagnostic Technologies—A Review

by John Paolo Ramoso, Manoochehr Rasekh and Wamadeva Balachandran

Biosensors 2025, 15(9), 586; https://doi.org/10.3390/bios15090586 - 6 Sep 2025

Viewed by 675

Abstract

Graphene, a two-dimensional carbon material with a hexagonal lattice structure, possesses remarkable properties. Exceptional electrical conductivity, mechanical strength, and high surface area that make it a powerful platform for biosensing applications. Its sp²-hybridised network facilitates efficient electron mobility and enables diverse [...] Read more.

Graphene, a two-dimensional carbon material with a hexagonal lattice structure, possesses remarkable properties. Exceptional electrical conductivity, mechanical strength, and high surface area that make it a powerful platform for biosensing applications. Its sp²-hybridised network facilitates efficient electron mobility and enables diverse surface functionalisation through bio-interfacing. This review highlights the core detection mechanisms in graphene-based biosensors. Optical sensing techniques, such as surface plasmon resonance (SPR) and surface-enhanced Raman scattering (SERS), benefit significantly from graphene’s strong light–matter interaction, which enhances signal sensitivity. Although graphene itself lacks intrinsic piezoelectricity, its integration with piezoelectric substrates can augment the performance of piezoelectric biosensors. In electrochemical sensing, graphene-based electrodes support rapid electron transfer, enabling fast response times across a range of techniques, including impedance spectroscopy, amperometry, and voltammetry. Graphene field-effect transistors (GFETs), which leverage graphene’s high carrier mobility, offer real-time, label-free, and highly sensitive detection of biomolecules. In addition, the review also explores multiplexed detection strategies vital for point-of-care diagnostics. Graphene’s nanoscale dimensions and tunable surface chemistry facilitate both array-based configurations and the simultaneous detection of multiple biomarkers. This adaptability makes graphene an ideal material for compact, scalable, and accurate biosensor platforms. Continued advancements in graphene biofunctionalisation, sensing modalities, and integrated multiplexing are driving the development of next-generation biosensors with superior sensitivity, selectivity, and diagnostic reliability. Full article

(This article belongs to the Special Issue Novel Graphene-Based Biosensors for Biomedical Applications)

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26 pages, 6690 KB

Open AccessArticle

Head-Specific Spatial Spectra of Electroencephalography Explained: A Sphara and BEM Investigation

by Uwe Graichen, Sascha Klee, Patrique Fiedler, Lydia Hofmann and Jens Haueisen

Biosensors 2025, 15(9), 585; https://doi.org/10.3390/bios15090585 - 6 Sep 2025

Viewed by 216

Abstract

Electroencephalography (EEG) is a non-invasive biosensing platform with a spatial-frequency content that is of significant relevance for a multitude of aspects in the neurosciences, ranging from optimal spatial sampling of the EEG to the design of spatial filters and source reconstruction. In the [...] Read more.

Electroencephalography (EEG) is a non-invasive biosensing platform with a spatial-frequency content that is of significant relevance for a multitude of aspects in the neurosciences, ranging from optimal spatial sampling of the EEG to the design of spatial filters and source reconstruction. In the past, simplified spherical head models had to be used for this analysis. We propose a method for spatial frequency analysis in EEG for realistically shaped volume conductors, and we exemplify our method with a five-compartment Boundary Element Method (BEM) model of the head. We employ the recently developed technique for spatial harmonic analysis (Sphara), which allows for spatial Fourier analysis on arbitrarily shaped surfaces in space. We first validate and compare Sphara with the established method for spatial Fourier analysis on spherical surfaces, discrete spherical harmonics, using a spherical volume conductor. We provide uncertainty limits for Sphara. We derive relationships between the signal-to-noise ratio (SNR) and the required spatial sampling of the EEG. Our results demonstrate that conventional 10–20 sampling might misestimate EEG power by up to 50%, and even 64 electrodes might misestimate EEG power by up to 15%. Our results also provide insights into the targeting problem of transcranial electric stimulation. Full article

(This article belongs to the Special Issue Biomarkers of Disability and Movement Disorders: Insights from Wearable Devices)

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30 pages, 6580 KB

Open AccessArticle

Advanced Nanomaterial-Based Electrochemical Biosensing of Loop-Mediated Isothermal Amplification Products

by Ana Kuprešanin, Marija Pavlović, Ljiljana Šašić Zorić, Milinko Perić, Stefan Jarić, Teodora Knežić, Ljiljana Janjušević, Zorica Novaković, Marko Radović, Mila Djisalov, Nikola Kanas, Jovana Paskaš and Zoran Pavlović

Biosensors 2025, 15(9), 584; https://doi.org/10.3390/bios15090584 - 5 Sep 2025

Viewed by 643

Abstract

The rapid and sensitive detection of regulatory elements within transgenic constructs of genetically modified organisms (GMOs) is essential for effective monitoring and control of their distribution. In this study, we present several innovative electrochemical biosensing platforms for the detection of regulatory sequences in [...] Read more.

The rapid and sensitive detection of regulatory elements within transgenic constructs of genetically modified organisms (GMOs) is essential for effective monitoring and control of their distribution. In this study, we present several innovative electrochemical biosensing platforms for the detection of regulatory sequences in genetically modified (GM) plants, combining the loop-mediated isothermal amplification (LAMP) method with electrodes functionalized by two-dimensional (2D) nanomaterials. The sensor design exploits the high surface area and excellent conductivity of reduced graphene oxide, Ti₃C₂T_x, and molybdenum disulfide (MoS₂) to enhance signal transduction. Furthermore, we used a “green synthesis” method for Ti₃C₂T_x preparation that eliminates the use of hazardous hydrofluoric acid (HF) and hydrochloric acid (HCl), providing a safer and more sustainable approach for nanomaterial production. Within this framework, the performance of various custom-fabricated electrodes, including laser-patterned gold leaf films, physical vapor deposition (PVD)-deposited gold electrodes, and screen-printed gold electrodes, is evaluated and compared with commercial screen-printed gold electrodes. Additionally, gold and carbon electrodes were electrochemically covered by gold nanoparticles (AuNPs), and their properties were compared. Several electrochemical methods were used during the DNA detection, and their importance and differences in excitation signal were highlighted. Electrochemical properties, sensitivity, selectivity, and reproducibility are characterized for each electrode type to assess the influence of fabrication methods and material composition on sensor performance. The developed biosensing systems exhibit high sensitivity, specificity, and rapid response, highlighting their potential as practical tools for on-site GMO screening and regulatory compliance monitoring. This work advances electrochemical nucleic acid detection by integrating environmentally-friendly nanomaterial synthesis with robust biosensing technology. Full article

(This article belongs to the Section Biosensor Materials)

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14 pages, 1771 KB

Open AccessArticle

A Bluetooth-Enabled Electrochemical Platform Based on Saccharomyces cerevisiae Yeast Cells for Copper Detection

by Ehtisham Wahid, Ohiemi Benjamin Ocheja, Antonello Longo, Enrico Marsili, Massimo Trotta, Matteo Grattieri, Cataldo Guaragnella and Nicoletta Guaragnella

Biosensors 2025, 15(9), 583; https://doi.org/10.3390/bios15090583 - 5 Sep 2025

Viewed by 1395

Abstract

Copper contamination in the environment poses significant risks to both soil and human health, making the need for reliable monitoring methods crucial. In this study, we report the use of the EmStat Pico module as potentiostat to develop a portable electrochemical biosensor for [...] Read more.

Copper contamination in the environment poses significant risks to both soil and human health, making the need for reliable monitoring methods crucial. In this study, we report the use of the EmStat Pico module as potentiostat to develop a portable electrochemical biosensor for copper detection, utilizing yeast Saccharomyces cerevisiae cells immobilized on a polydopamine (PDA)-coated screen-printed electrode (SPE). By optimizing the sensor design with a horizontal assembly and the volume reduction in the electrolyte solution, we achieved a 10-fold increase in current density with higher range of copper concentrations (0–300 µM CuSO₄) compared to traditional (or previous) vertical dipping setups. Additionally, the use of genetically engineered copper-responsive yeast cells further improved sensor performance, with the recombinant strain showing a 1.7-fold increase in current density over the wild-type strain. The biosensor demonstrated excellent reproducibility (R² > 0.95) and linearity over a broad range of copper concentrations, making it suitable for precise quantitative analysis. To further enhance portability and usability, a Bluetooth-enabled electrochemical platform was integrated with a web application for real-time data analysis, enabling on-site monitoring and providing a reliable, cost-effective tool for copper detection in real world settings. This system offers a promising solution for addressing the growing need for efficient environmental monitoring, especially in agriculture. Full article

(This article belongs to the Special Issue Sensors for Environmental Monitoring and Food Safety—2nd Edition)

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14 pages, 3684 KB

Open AccessArticle

Accuracy Enhancement in Refractive Index Sensing via Full-Spectrum Machine Learning Modeling

by Majid Aalizadeh, Chinmay Raut, Morteza Azmoudeh Afshar, Ali Tabartehfarahani and Xudong Fan

Biosensors 2025, 15(9), 582; https://doi.org/10.3390/bios15090582 - 5 Sep 2025

Viewed by 310

Abstract

We present a full-spectrum machine learning framework for refractive index sensing using simulated absorption spectra from meta-grating structures composed of titanium or silicon nanorods under TE and TM polarizations. Linear regression was applied to 80 principal components extracted from each spectrum, and model [...] Read more.

We present a full-spectrum machine learning framework for refractive index sensing using simulated absorption spectra from meta-grating structures composed of titanium or silicon nanorods under TE and TM polarizations. Linear regression was applied to 80 principal components extracted from each spectrum, and model performance was assessed using five-fold cross-validation, simulating real-world biosensing scenarios where unknown patient samples are predicted based on standard calibration data. Titanium-based structures, dominated by broadband intensity changes, yielded the lowest mean squared errors and the highest accuracy improvements—up to an 8128-fold reduction compared to the best single-feature model. In contrast, silicon-based structures, governed by narrow resonances, showed more modest gains due to spectral nonlinearity that limits the effectiveness of global linear models. We also show that even the best single-wavelength predictor is identified through data-driven analysis, not visual selection, highlighting the value of automated feature preselection. These findings demonstrate that spectral shape plays a key role in modeling performance and that full-spectrum linear approaches are especially effective for intensity-modulated index sensors. Full article

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

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16 pages, 3627 KB

Open AccessArticle

In Vivo Study on the Safe Use of a Novel Intraoperative Sensing Tool for Tissue Stiffness Assessment in Endoscopic Surgery

by Georgios Violakis, Pantelis Antonakis, Emmanouil Kritsotakis, Theodoros Kozonis, Leonidas Chardalias, Apostolos Papalois, Georgios Agrogiannis, Effrosyni Kampouroglou, Nikolaos Vardakis, Stylianos Kostakis, Eleni Athanasaki, Zhenyu Zhang, Martin Angelmahr, Manousos Konstadoulakis and Panagiotis Polygerinos

Biosensors 2025, 15(9), 581; https://doi.org/10.3390/bios15090581 - 5 Sep 2025

Viewed by 351

Abstract

A novel endoscopic palpation tool (EPT), designed for tactile and stiffness sensing using fiber Bragg gratings (FBGs) was evaluated in a surgical environment for intraoperative safety and effectiveness. The EPT consisted of four FBGs arranged in a cross pattern and embedded within an [...] Read more.

A novel endoscopic palpation tool (EPT), designed for tactile and stiffness sensing using fiber Bragg gratings (FBGs) was evaluated in a surgical environment for intraoperative safety and effectiveness. The EPT consisted of four FBGs arranged in a cross pattern and embedded within an elastic, hollow, silicone hemispherical dome designed to deform upon contact with soft tissue. The EPT was employed to scan both in vivo and ex vivo tissue samples. Monitoring of porcine vital signs during minimally invasive and open surgical procedures showed no significant changes during use of the EPT. Perioperative blood tests including inflammatory markers and liver and renal function studies were unremarkable. Histopathological analyses of tissues involved (liver, spleen, bowel, and abdominal wall) showed no evidence of inflammation, necrosis, or tissue damage, confirming the device’s biocompatibility. To the best of our knowledge, this is the first study reporting in vivo stiffness measurements using an FBG-based EPT. The probe successfully distinguished between soft and hard tissue regions’ relative stiffness. Furthermore, successive measurements on liver samples demonstrated the device’s ability to generate stiffness maps, enabling clear visualization of spatial variation in tissue stiffness. Full article

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

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32 pages, 5916 KB

Open AccessReview

Advances and Innovations in Conjugated Polymer Fluorescent Sensors for Environmental and Biological Detection

by Viet-Duc Phung and Vinh Van Tran

Biosensors 2025, 15(9), 580; https://doi.org/10.3390/bios15090580 - 4 Sep 2025

Viewed by 416

Abstract

Thanks to their multiple outstanding features—such as high fluorescence quantum yield, good photostability, and excellent sensitivity—conjugated polymers (CPs) have emerged as a pioneering class of fluorescent materials for sensing applications, particularly in environmental and biological fields, for the detection of a wide range [...] Read more.

Thanks to their multiple outstanding features—such as high fluorescence quantum yield, good photostability, and excellent sensitivity—conjugated polymers (CPs) have emerged as a pioneering class of fluorescent materials for sensing applications, particularly in environmental and biological fields, for the detection of a wide range of environmental pollutants and bioactive compounds. The presence of delocalized π-electrons in the CP backbone significantly enhances sensing performance through a unique phenomenon known as the “molecular wire effect.” As a result, CP-based fluorescent sensors have been extensively developed and employed as exceptional tools for monitoring various analytes in environmental and biological contexts. A deep understanding of their unique properties, fabrication techniques, and recent innovations is essential for guiding the strategic development of advanced CP-based fluorescent sensors, particularly for future point-of-care applications. This study presents a critical review of the key characteristics of fluorescent sensors and highlights several common types of conjugated polymers (CPs) used in their design and fabrication. It summarizes and discusses the main sensing mechanisms, state-of-the-art applications, and recent innovations of CP-based fluorescent sensors for detecting target compounds in environmental and biological fields. Furthermore, potential strategies and future perspectives for designing and developing high-performance CP-based fluorescent sensors are emphasized. By consolidating current scientific evidence, this review aims to support the advancement of highly sensitive fluorescent sensors based on various CP nanoparticles for environmental and biological applications. Full article

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

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17 pages, 1568 KB

Open AccessArticle

Cell-Free DNA Versus Circulating Tumor Cells: A Pilot Study of Alpha-Fetoprotein Analysis for Diagnosis and Treatment Monitoring in Hepatocellular Carcinoma

by Ga Young Moon, Hyun Sung Park, Ha Neul Kim, Hei-Gwon Choi, Yonghan Han, Hyuk Soo Eun, Tae Hee Lee and Jiyoon Bu

Biosensors 2025, 15(9), 579; https://doi.org/10.3390/bios15090579 - 4 Sep 2025

Viewed by 422

Abstract

Serum alpha-fetoprotein (AFP) is widely used for hepatocellular carcinoma (HCC) management, yet its limited sensitivity and specificity restrict diagnostic and prognostic utility. In this study, we explore the clinical potential of AFP quantification from cell-free DNA (cfDNA) and circulating tumor cells (CTCs) using [...] Read more.

Serum alpha-fetoprotein (AFP) is widely used for hepatocellular carcinoma (HCC) management, yet its limited sensitivity and specificity restrict diagnostic and prognostic utility. In this study, we explore the clinical potential of AFP quantification from cell-free DNA (cfDNA) and circulating tumor cells (CTCs) using a novel bead-based liquid biopsy platform. Following isolation, AFP abundance in cfDNA was quantified by qPCR, while AFP protein expression in CTCs was assessed via immunohistochemistry. Compared to serum AFP, cfDNA-derived AFP demonstrated significantly greater diagnostic accuracy in distinguishing HCC patients from non-cancerous individuals (p < 0.0001, AUC = 0.998), while AFP⁺ CTCs showed high specificity. Post-treatment changes in AFP levels from cfDNA and CTCs were significantly associated with therapeutic response and overall survival, outperforming conventional serum AFP. Longitudinal monitoring further revealed that cfDNA AFP levels reliably captured recurrence events prior to clinical diagnosis. Moreover, a combined metric integrating AFP levels from cfDNA and CTCs significantly improved response stratification (AUC = 0.89), outperforming individual biomarkers. This pilot study highlights the potential of multimodal AFP profiling through cfDNA and CTCs as a promising, non-invasive approach for enhancing diagnosis, prognosis, and treatment monitoring in HCC, with direct implications for personalized therapeutic strategies. Full article

(This article belongs to the Special Issue Advanced Cell-Analyzing Technologies and Their Biosensing Applications)

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