Biosensors

23 pages, 6590 KiB

Open AccessArticle

Numerical Study of a Novel Kagome-Inspired Photonic Crystal Fiber-Based Surface Plasmon Resonance Biosensor for Detection of Blood Components and Analytical Targets

by Ayushman Ramola, Amit Kumar Shakya, Ali Droby and Arik Bergman

Biosensors 2025, 15(8), 539; https://doi.org/10.3390/bios15080539 - 15 Aug 2025

Abstract

This numerical study introduces a surface plasmon resonance (SPR)-based biosensor utilizing a kagome lattice-inspired hollow core photonic crystal fiber (PCF) for the highly sensitive detection of various blood biomarkers and analytical components. The sensor is designed to detect key blood biomarkers such as [...] Read more.

This numerical study introduces a surface plasmon resonance (SPR)-based biosensor utilizing a kagome lattice-inspired hollow core photonic crystal fiber (PCF) for the highly sensitive detection of various blood biomarkers and analytical components. The sensor is designed to detect key blood biomarkers such as water, glucose, plasma, and hemoglobin (Hb), as well as analytical targets including krypton, sylgard, ethanol, polyacrylamide (PA), and bovine serum albumin (BSA), by monitoring shifts in the resonance wavelength (RW). A dual-polarization approach is employed by analyzing both transverse magnetic (TM) and transverse electric (TE) modes. The proposed sensor demonstrates exceptional performance, achieving maximum wavelength sensitivities (Sw) of 18,900 nm RIU⁻¹ for TM pol. and 16,800 nm RIU⁻¹ for TE pol. Corresponding peak amplitude sensitivities (S_A) of 71,224 RIU⁻¹ for TM pol. and 58,112 RIU⁻¹ for TE pol. were also observed. The peak sensor resolution (S_R) for both modes is on the order of 10⁻⁶ RIU, underscoring its high precision. Owing to its enhanced sensitivity, compact design, and robust dual-polarization capability, the proposed biosensor holds strong promise for point-of-care diagnostics and real-time blood component analysis. Full article

(This article belongs to the Special Issue Surface Plasmon Resonance-Based Biosensors and Their Applications)

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15 pages, 1103 KiB

Open AccessArticle

Development of a Novel Aptamer-Antibody Sandwich Chemiluminescent Biosensor and Its Application in the Detection of Aflatoxin B₁

by Zhike Zhao, Jianghao Feng and Caizhang Wu

Biosensors 2025, 15(8), 538; https://doi.org/10.3390/bios15080538 - 15 Aug 2025

Abstract

In addressing the challenges posed by high costs, low accuracy, and cumbersome operations in mycotoxin detection, a novel aptamer-antibody sandwich chemiluminescent biosensor for detecting aflatoxin B₁ (AFB₁) was developed. The indirect competition between AFB₁, aflatoxin B₁-ovomucoid [...] Read more.

In addressing the challenges posed by high costs, low accuracy, and cumbersome operations in mycotoxin detection, a novel aptamer-antibody sandwich chemiluminescent biosensor for detecting aflatoxin B₁ (AFB₁) was developed. The indirect competition between AFB₁, aflatoxin B₁-ovomucoid complete antigen (AFB₁-OVA), and rabbit anti-ovomucoid (OVA) antibody results in the formation of a sandwich complex. This sandwich assay is linked to a horseradish peroxidase-labeled antibody, which catalyzes luminol chemiluminescence for the indirect detection of AFB₁. The biosensor was designed to operate with high precision, low cost, and a low detection limit for AFB₁, which is contingent upon experimental conditions such as pH, reagent concentration, temperature, and incubation time. The optimization of pH, aptamer concentration, competitive incubation time, competitive incubation temperature, and HRP-labeled antibody concentration was instrumental in achieving these objectives. Experimental findings demonstrated that the sensor’s detection limit was 0.067 ng/mL, exhibiting excellent linearity (R² = 0.99679) within the concentration range of 0.25–10 ng/mL. The recovery rate of spiked samples ranged from 94.4% to 108.05%. This sensor boasts a low detection limit, straightforward operation, and minimal cost, thus offering a novel solution for developing cost-effective, high-precision mycotoxin detection methods. Full article

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

16 pages, 2449 KiB

Open AccessArticle

Enzyme-Free Monitoring of Glucose Using Molecularly Imprinted Polymers and Gold Nanoparticles

by Ana Rita Aires Cardoso, Pedro Miguel Cândido Barquinha and Maria Goreti Ferreira Sales

Biosensors 2025, 15(8), 537; https://doi.org/10.3390/bios15080537 - 15 Aug 2025

Abstract

This work describes a non-enzymatic electrochemical glucose biosensor combining for the first time molecularly imprinted polymers (MIPs) for glucose concentration and gold nanoparticles (AuNPs) on screen-printed carbon electrodes (SPEs), where both MIPs and AuNPs were assembled in situ. Electrochemical impedance spectroscopy (EIS) was [...] Read more.

This work describes a non-enzymatic electrochemical glucose biosensor combining for the first time molecularly imprinted polymers (MIPs) for glucose concentration and gold nanoparticles (AuNPs) on screen-printed carbon electrodes (SPEs), where both MIPs and AuNPs were assembled in situ. Electrochemical impedance spectroscopy (EIS) was used to evaluate the analytical performance of the sensor, which has a linear range between 1.0 µM and 1.0 mM when standard solutions are prepared in buffer. Direct measurement of glucose was performed by chronoamperometry, measuring the oxidation current generated during direct glucose oxidation. The selectivity was tested against ascorbic acid and the results confirmed a selective discrimination of the electrode for glucose. Overall, the work presented here represents a promising tool for tracking glucose levels in serum. The use of glucose MIP on the electrode surface allows the concentration of glucose, resulting in lower detection limits, and the use of AuNPs reduces the potential required for the oxidation of glucose, which increases selectivity. In addition, this possible combination of two analytical measurements following different theoretical concepts can contribute to the accuracy of the analytical measurements. This combination can also be extended to other biomolecules that can be electrochemically oxidised at lower potentials. Full article

(This article belongs to the Special Issue Molecularly Imprinted Polymers in Biosensors: Assembly, Characterization and Applications)

13 pages, 7712 KiB

Open AccessArticle

Bifunctional TiO₂@AgNP Superstructures as a SERS-Sensing Platform for Identifying Flavonoids in Chinese Herbal Medicine

by Yulin Li, Jubo Li, Haisu Wang, Shaorui Qi, Zhehao Zhang, Yaqiu Wang, Ying Wang and Wei Ji

Biosensors 2025, 15(8), 536; https://doi.org/10.3390/bios15080536 - 15 Aug 2025

Abstract

Acanthopanax senticosus is an essential medicinal herb in traditional Chinese medicine, with its pharmacological properties largely attributed to bioactive flavonoids. The types and amounts of these flavonoids act as vital quality markers for both the raw materials and the resultant products. In this [...] Read more.

Acanthopanax senticosus is an essential medicinal herb in traditional Chinese medicine, with its pharmacological properties largely attributed to bioactive flavonoids. The types and amounts of these flavonoids act as vital quality markers for both the raw materials and the resultant products. In this work, we introduce a TiO₂@AgNP nanocomposite designed as a surface-enhanced Raman scattering (SERS) sensor aimed at the preliminary quantification and identification of flavonoids. This is achieved by leveraging the effective molecular adsorption properties of TiO₂ alongside the ‘hot spots’ generated by AgNPs. By optimizing SERS performance through adjustment of the molar ratio between TiO₂ and Ag, we can quantitatively evaluate four flavonoids—luteolin, kaempferol, quercetin, and rutin—with low detection concentrations of 10⁻⁶ M, 10⁻⁵ M, 5 × 10⁻⁶ M, and 10⁻⁶ M, respectively. Additionally, we observe a nearly linear relationship between the SERS signals and the flavonoid concentrations, allowing for dual or multiplex analysis of these compounds. Furthermore, we successfully differentiated Acanthopanax senticosus samples from six different geographical regions in China based on the detection of significant flavonoid constituents. This serves as a proof of concept for practical applications that can enhance the identification and distinction of traditional Chinese medicine, as well as assess quality and medicinal efficacy. Full article

(This article belongs to the Special Issue Surface-Enhanced Raman Scattering in Biosensing Applications)

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24 pages, 3609 KiB

Open AccessReview

Droplet-Based Microfluidics in Single-Bacterium Analysis: Advancements in Cultivation, Detection, and Application

by Haiyan Ma, Yuewen Zhang, Ren Shen and Yanwei Jia

Biosensors 2025, 15(8), 535; https://doi.org/10.3390/bios15080535 - 15 Aug 2025

Abstract

Microorganisms exhibit remarkable diversity, making their comprehensive characterization essential for understanding ecosystem functioning and safeguarding human health. However, traditional culture-based methods entail inherent limitations for resolving microbial heterogeneity, isolating slow-growing microorganisms, and accessing uncultivated microbes. Conversely, droplet-based microfluidics enables a high-throughput and precise [...] Read more.

Microorganisms exhibit remarkable diversity, making their comprehensive characterization essential for understanding ecosystem functioning and safeguarding human health. However, traditional culture-based methods entail inherent limitations for resolving microbial heterogeneity, isolating slow-growing microorganisms, and accessing uncultivated microbes. Conversely, droplet-based microfluidics enables a high-throughput and precise platform for single-bacterium manipulation by physically isolating individual cells within microdroplets. This technology presents a transformative approach to overcoming the constraints of conventional techniques. This review outlines the fundamental principles, recent research advances, and key application domains of droplet-based microfluidics, with a particular focus on innovations in single-bacterium encapsulation, sorting, cultivation, and functional analysis. Applications such as antibiotic susceptibility testing, enzyme-directed evolution screening, microbial interaction studies, and the cultivation of novel bacterial species are discussed, underscoring the technology’s broad potential in microbiological research and biotechnology. Full article

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

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16 pages, 1307 KiB

Open AccessArticle

Kinetic Analysis of SARS-CoV-2 S1–Integrin Binding Using Live-Cell, Label-Free Optical Biosensing

by Nicolett Kanyo, Krisztina Borbely, Beatrix Peter, Kinga Dora Kovacs, Anna Balogh, Beatrix Magyaródi, Sandor Kurunczi, Inna Szekacs and Robert Horvath

Biosensors 2025, 15(8), 534; https://doi.org/10.3390/bios15080534 - 14 Aug 2025

Abstract

The SARS-CoV-2 spike (S1) protein facilitates viral entry through binding to angiotensin-converting enzyme 2 (ACE2), but it also contains an Arg–Gly–Asp (RGD) motif that may enable interactions with RGD-binding integrins on ACE2-negative cells. Here, we provide quantitative evidence for this alternative binding pathway [...] Read more.

The SARS-CoV-2 spike (S1) protein facilitates viral entry through binding to angiotensin-converting enzyme 2 (ACE2), but it also contains an Arg–Gly–Asp (RGD) motif that may enable interactions with RGD-binding integrins on ACE2-negative cells. Here, we provide quantitative evidence for this alternative binding pathway using a live-cell, label-free resonant waveguide grating (RWG) biosensor. RWG technology allowed us to monitor real-time adhesion kinetics of live cells to RGD-displaying substrates, as well as cell adhesion to S1-coated surfaces. To characterize the strength of the integrin–S1 interaction, we determined the dissociation constant using two complementary approaches. First, we performed a live-cell competitive binding assay on RGD-displaying surfaces, where varying concentrations of soluble S1 were added to cell suspensions. Second, we recorded the adhesion kinetics of cells on S1-coated surfaces and fitted the data using a kinetic model based on coupled ordinary differential equations. By comparing the results from both methods, we estimate that approximately 33% of the S1 molecules immobilized on the Nb₂O₅ biosensor surface are capable of initiating integrin-mediated adhesion. These findings support the existence of an alternative integrin-dependent entry route for SARS-CoV-2 and highlight the effectiveness of label-free RWG biosensing for quantitatively probing virus–host interactions under physiologically relevant conditions without the need of the isolation of the interaction partners from the cells. Full article

(This article belongs to the Special Issue In Honor of Prof. Evgeny Katz: Biosensors: Science and Technology)

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15 pages, 1609 KiB

Open AccessArticle

Simultaneous Routing with Washing Droplets Based on Shape-Dependent Velocity Model in MEDA Biochips

by Chiharu Shiro, Hiroki Nishikawa, Xiangbo Kong, Hiroyuki Tomiyama and Shigeru Yamashita

Biosensors 2025, 15(8), 533; https://doi.org/10.3390/bios15080533 - 14 Aug 2025

Abstract

Micro Electrode Dot Array (MEDA) biochips have recently attracted considerable attention in the biochemical and medical industries. MEDA biochips manipulate micro droplets for biochemical experiments such as DNA analysis. Droplets on MEDA biochips are moved using the Electrowetting on Dielectric (EWOD) effect, but [...] Read more.

Micro Electrode Dot Array (MEDA) biochips have recently attracted considerable attention in the biochemical and medical industries. MEDA biochips manipulate micro droplets for biochemical experiments such as DNA analysis. Droplets on MEDA biochips are moved using the Electrowetting on Dielectric (EWOD) effect, but a portion of a droplet may remain on a cell after passing through, contaminating the cell. Other droplets cannot pass through a contaminated cell. In previous studies, contaminated cells were considered unavailable for droplet routing. As the number of contaminated cells increases, droplets may be prevented from moving to the desired position. Therefore, we propose a method for simultaneous routing of target functional and washing droplets based on a shape-dependent velocity model. In a simulation, the proposed method reduced the routing time by about 10% compared with an existing method. Full article

(This article belongs to the Special Issue Microfluidics for Biomedical Applications (3rd Edition))

16 pages, 6084 KiB

Open AccessArticle

First Design of a Contact Lens for Diagnosis of Dehydration

by Kundan Sivashanmugan, Reece E. Albert and Joseph R. Lakowicz

Biosensors 2025, 15(8), 532; https://doi.org/10.3390/bios15080532 - 14 Aug 2025

Abstract

Dehydration is a serious medical problem for elderly patients and young children. The most widely used diagnostics are measurements of sodium ion (Na⁺) and potassium ion (K⁺) in blood serum. Dehydration is difficult to diagnose even by trained health [...] Read more.

Dehydration is a serious medical problem for elderly patients and young children. The most widely used diagnostics are measurements of sodium ion (Na⁺) and potassium ion (K⁺) in blood serum. Dehydration is difficult to diagnose even by trained health care professionals because the body compensates to maintain the appearance of skin. These measurements required a blood draw because specific tests are generally not available for only Na⁺ and K⁺. The blood samples are analyzed by an electrolyte panel (EP) or a basic metabolic panel (BMP). Most hospitals limit EP and BMP to one per day to control costs. More frequent measurements of Na⁺ and K⁺ are needed, especially during rehydration. We designed a dehydration contact lens that can provide the Na⁺ and K⁺ concentrations as needed or for continuous monitoring. The measurements are obtained from the fluorescent lifetime or wavelength-ratiometric intensities of the Na⁺- and K⁺-sensitive fluorophores. The dehydration contact lens does not contain electronic components and are inexpensive to prepare. Full article

(This article belongs to the Special Issue Advanced Fluorescence Biosensors)

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15 pages, 3400 KiB

Open AccessArticle

Ti₃C₂T_X MXene/Polyaniline-Modified Nylon Fabric Electrode for Wearable Non-Invasive Glucose Monitoring in Sweat

by Lichao Wang, Meng Li, Shengnan Ya, Hang Tian, Kerui Li, Qinghong Zhang, Yaogang Li, Hongzhi Wang and Chengyi Hou

Biosensors 2025, 15(8), 531; https://doi.org/10.3390/bios15080531 - 14 Aug 2025

Abstract

Sweat-based electrochemical sensors for wearable applications have attracted substantial interest due to their non-invasive nature, compact design, and ability to provide real-time data. Remarkable advancements have been made in integrating these devices into flexible platforms. While thin-film polymer substrates are frequently employed for [...] Read more.

Sweat-based electrochemical sensors for wearable applications have attracted substantial interest due to their non-invasive nature, compact design, and ability to provide real-time data. Remarkable advancements have been made in integrating these devices into flexible platforms. While thin-film polymer substrates are frequently employed for their durability, the prolonged buildup of sweat on such materials can disrupt consistent sensing performance and adversely affect skin comfort over extended periods. Therefore, investigating lightweight, comfortable, and breathable base materials for constructing working electrodes is essential for producing flexible and breathable sweat electrochemical sensors. In this study, nylon fabric was chosen as the base material for constructing the working electrode. The electrode is prepared using a straightforward printing process, incorporating Ti₃C₂T_X MXene/polyaniline and methylene blue as modification materials in the electronic intermediary layer. The synergistic effect of the modified layer and the multi-level structure of the current collector enhances the electrochemical kinetics on the electrode surface, improves electron transmission efficiency, and enables the nylon fabric-based electrode to accurately and selectively measure glucose concentration in sweat. It exhibits a wide linear range (0.04~3.08 mM), high sensitivity (3.11 μA·mM⁻¹), strong anti-interference capabilities, and high stability. This system can monitor glucose levels and trends in sweat, facilitating the assessment of daily sugar intake for personal health management. Full article

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

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11 pages, 1327 KiB

Open AccessArticle

All-in-One Sustainable Thread Biosensor for Chemiluminescence Smartphone Detection of Lactate in Sweat

by Emanuela Maiorano, Maria Maddalena Calabretta, Eugenio Lunedei and Elisa Michelini

Biosensors 2025, 15(8), 530; https://doi.org/10.3390/bios15080530 - 13 Aug 2025

Abstract

Thanks to their low-cost, portability, and sustainability, microfluidic thread-based analytical devices (μTADs) are emerging as an attractive analytical platform for wearable biosensing. While several μTADs, mainly based on colorimetric and electrochemical detection methods, have been developed, achieving the needed sensitivity and accuracy for [...] Read more.

Thanks to their low-cost, portability, and sustainability, microfluidic thread-based analytical devices (μTADs) are emerging as an attractive analytical platform for wearable biosensing. While several μTADs, mainly based on colorimetric and electrochemical detection methods, have been developed, achieving the needed sensitivity and accuracy for these biosensors continues to present a significant challenge. Prompted by this need we investigated for the first time the implementation of chemiluminescence (CL) as a detection technique for μTADs. Exploiting the lactate oxidase-catalyzed reaction coupled with the enhanced luminol/H₂O₂/horseradish peroxidase CL system, we developed a cotton-thread-based chemiluminescent device enabling the detection of lactate with a limit of detection of 0.25 mM in a 2 µL volume of artificial sweat at pH 6.5 within 3 min. The use of recycled grape skin as support made the device sustainable, while the smartphone detection allowed a simple and quantitative readout for the end-user. Using a smartphone as a detector, the analytical performance was evaluated in different conditions and in the presence of potential interferents, showing suitability for monitoring lactate levels in physiological conditions, such as for monitoring anaerobic thresholds in endurance training. Full article

(This article belongs to the Special Issue Advanced Biosensing and Bioimaging by Nanomaterials and Machine Learning)

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13 pages, 2094 KiB

Open AccessArticle

Laser-Assisted Visible-Light Polymerization for Rapid Synthesis of Molecularly Imprinted Polymers

by Wissal Mrabet, Abdelhafid Karrat and Aziz Amine

Biosensors 2025, 15(8), 529; https://doi.org/10.3390/bios15080529 - 13 Aug 2025

Abstract

The demand for rapid, energy-efficient, and low-toxicity methods for synthesizing molecularly imprinted polymers (MIPs) is increasing, particularly for applications in environmental monitoring and green chemistry. In this context, the present work focuses on the development of a novel laser-assisted method for MIP synthesis, [...] Read more.

The demand for rapid, energy-efficient, and low-toxicity methods for synthesizing molecularly imprinted polymers (MIPs) is increasing, particularly for applications in environmental monitoring and green chemistry. In this context, the present work focuses on the development of a novel laser-assisted method for MIP synthesis, employing a visible laser (450 nm) and erythrosine B as a green photoinitiator. This visible-light approach enables fast and spatially controlled polymerization while avoiding the drawbacks of conventional methods (thermal heating, UV synthesis), such as the use of toxic initiators like AIBN and the need for UV shielding. MIPs were synthesized for bisphenol A and sulfamethoxazole, two emerging contaminants of significant environmental concern. The synthesis process was optimized for rapidity and scalability, and the resulting MIPs were integrated into a paper-based analytical device (MIP-PAD) for smartphone-assisted, on-site detection. The developed sensors exhibited excellent analytical performance, with recovery rates of 98.6% in tap water and 90.2% in river water and relative standard deviations (RSDs) below 1.88%. This study demonstrated a green, efficient, and highly controllable laser-assisted polymerization technique, offering a promising alternative to conventional MIP synthesis methods. Full article

(This article belongs to the Special Issue Molecularly Imprinted Polymers in Biosensors: Assembly, Characterization and Applications)

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12 pages, 2021 KiB

Open AccessArticle

Dual-Mode Optical Detection of Sulfide Ions Using Copper-Anchored Nitrogen-Doped Graphene Quantum Dot Nanozymes

by Van Anh Ngoc Nguyen, Trung Hieu Vu, Phuong Thy Nguyen and Moon Il Kim

Biosensors 2025, 15(8), 528; https://doi.org/10.3390/bios15080528 - 13 Aug 2025

Abstract

We present a dual-mode optical sensing strategy for selective and sensitive detection of sulfide ions (S²⁻), employing copper-anchored nitrogen-doped graphene quantum dots (Cu@N-GQDs) as bifunctional nanozymes. The Cu@N-GQDs were synthesized via citric acid pyrolysis in the presence of ammonium hydroxide (serving [...] Read more.

We present a dual-mode optical sensing strategy for selective and sensitive detection of sulfide ions (S²⁻), employing copper-anchored nitrogen-doped graphene quantum dots (Cu@N-GQDs) as bifunctional nanozymes. The Cu@N-GQDs were synthesized via citric acid pyrolysis in the presence of ammonium hydroxide (serving as both nitrogen source and reductant) and copper chloride, leading to uniform incorporation of copper oxide species onto the N-GQD surface. The resulting nanohybrids exhibit two synergistic functionalities: intrinsic fluorescence comparable to pristine N-GQDs, and significantly enhanced peroxidase-like catalytic activity attributed to the anchored copper species. Upon interaction with sulfide ions, the system undergoes a dual-optical response: (i) fluorescence quenching via Cu-S complexation, and (ii) inhibition of peroxidase-like activity due to the deactivation of Cu catalytic centers via the interaction with S²⁻. This dual-signal strategy enables sensitive quantification of S²⁻, achieving detection limits of 0.5 µM (fluorescence) and 3.5 µM (colorimetry). The sensor demonstrates excellent selectivity over competing substances and high reliability and precision in real tap water samples. These findings highlight the potential of Cu@N-GQDs as robust, bifunctional, and field-deployable nanozyme probes for environmental and biomedical sulfide ion monitoring. Full article

(This article belongs to the Special Issue Advanced Optics and Photonics in Biosensing Applications)

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15 pages, 2864 KiB

Open AccessArticle

Rapid Detection of Staphylococcus aureus in Milk Samples by DNA Nanodendrimer-Based Fluorescent Biosensor

by Mukaddas Mijit, Dongxia Pan, Hui Wang, Chaoqun Sun and Liang Yang

Biosensors 2025, 15(8), 527; https://doi.org/10.3390/bios15080527 - 12 Aug 2025

Abstract

Staphylococcus aureus is the primary pathogen responsible for mastitis in dairy cows and foodborne illnesses, posing a significant threat to public health and food safety. Here, we developed an enhanced sensor based on solid-phase separation using gold-magnetic nanoparticles (Au@Fe₃O₄) [...] Read more.

Staphylococcus aureus is the primary pathogen responsible for mastitis in dairy cows and foodborne illnesses, posing a significant threat to public health and food safety. Here, we developed an enhanced sensor based on solid-phase separation using gold-magnetic nanoparticles (Au@Fe₃O₄) and signal amplification via dendritic DNA nanostructures. The substrate chain was specifically immobilized using thiol–gold coordination, and a three-dimensional dendritic structure was constructed through sequential hybridization of DNAzymes, L chains, and Y chains, resulting in a 2.8-fold increase in initial fluorescence intensity. Upon specific cleavage of the substrate chain at the rA site by S. aureus DNA, the complex dissociates, resulting in fluorescence intensity decay. The fluorescence intensity is negatively correlated with the concentration of Staphylococcus aureus. After optimization, the biosensor maintains a detection limit of 1 CFU/mL within 3 min, with a linear range extended to 1–10⁷ CFU/mL (R² = 0.998) and recovery rates of 85.6–102.1%, significantly enhancing resistance to matrix interference. This provides an innovative solution for rapid on-site detection of foodborne pathogens. Full article

(This article belongs to the Special Issue The Application of Biomaterials in Electronics and Biosensors)

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18 pages, 2250 KiB

Open AccessArticle

Fumonisin B Determination in Maize Products from Belize Using an Immunosensor Based on Screen-Printed Carbon Electrodes

by Beatriz Pérez-Fernández, Britt Marianna Maestroni, Carlotta Cozzani, Colette Eusey, Natalie Gibson, Alfredo de la Escosura-Muñiz and Christina Vlachou

Biosensors 2025, 15(8), 526; https://doi.org/10.3390/bios15080526 - 12 Aug 2025

Abstract

A competitive electrochemical immunosensor, using screen-printed carbon electrodes (SPCEs), was developed for the determination of total fumonisins (sum of FB1, FB2 and FB3) extracted with a simple solvent extraction and dilution method, without clean up, from maize flour and maize tortillas. The optimized [...] Read more.

A competitive electrochemical immunosensor, using screen-printed carbon electrodes (SPCEs), was developed for the determination of total fumonisins (sum of FB1, FB2 and FB3) extracted with a simple solvent extraction and dilution method, without clean up, from maize flour and maize tortillas. The optimized biosensor has a linear range of 0.25 to 50 µg/L with 3% and 2% reproducibility for FB1 and (FB1 + FB2), respectively, and a linear range of 0.25 to 10 µg/L with 2% reproducibility for (FB1 + FB2 + FB3). The limits of detection and quantification in PBS buffer for total fumonisins are 0.12 µg/L and 0.39 µg/L, respectively. These values in the maize matrix are 6.07 µg/kg and 20.25 µg/kg, respectively. In addition, the stability and the selectivity of the sensor were studied. The immunosensor was validated with liquid chromatography–tandem mass spectrometry. This novel biosensor is more rapid, simpler and cheaper than current methods, and can also be used at the point of need. Full article

(This article belongs to the Special Issue Applications of Cutting-Edge Biosensors in Environment, Food and Healthcare Field)

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24 pages, 2773 KiB

Open AccessArticle

Highly Sensitive SOI-TFET Gas Sensor Utilizing Tailored Conducting Polymers for Selective Molecular Detection and Microbial Biosensing Integration

by Mohammad K. Anvarifard and Zeinab Ramezani

Biosensors 2025, 15(8), 525; https://doi.org/10.3390/bios15080525 - 11 Aug 2025

Abstract

We present a highly sensitive and selective gas sensor based on an advanced silicon-on-insulator tunnel field-effect transistor (SOI-TFET) architecture, enhanced through the integration of customized conducting polymers. In this design, traditional metal gates are replaced with distinct functional polymers—PPP-TOS/AcCN, PP-TOS/AcCN, PP-FE(CN)₆³⁻ [...] Read more.

We present a highly sensitive and selective gas sensor based on an advanced silicon-on-insulator tunnel field-effect transistor (SOI-TFET) architecture, enhanced through the integration of customized conducting polymers. In this design, traditional metal gates are replaced with distinct functional polymers—PPP-TOS/AcCN, PP-TOS/AcCN, PP-FE(CN)₆³⁻/H₂O, PPP-TCNQ-TOS/AcCN, and PPP-ClO₄/AcCN—which enable precise molecular recognition and discrimination of various target gases. To further enhance sensitivity, the device employs an oppositely doped source region, significantly improving gate control and promoting stronger band-to-band tunneling. This structural modification amplifies sensing signals and improves noise immunity, allowing reliable detection at trace concentrations. Additionally, optimization of the subthreshold swing contributes to faster switching and response times. Thermal stability is addressed by embedding a P-type buffer layer within the buried oxide, which increases thermal conductivity and reduces lattice temperature, further stabilizing device performance. Experimental results demonstrate that the proposed sensor outperforms conventional SOI-TFET designs, exhibiting superior sensitivity and selectivity toward analytes such as methanol, chloroform, isopropanol, and hexane. Beyond gas sensing, the unique polymer-functionalized gate design enables integration of microbial biosensing capabilities, making the platform highly versatile for biochemical detection. This work offers a promising pathway toward ultra-sensitive, low-power sensing technologies for environmental monitoring, industrial safety, and medical diagnostics. Full article

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

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40 pages, 14675 KiB

Open AccessReview

Recent Advances in Hydrogel-Promoted Photoelectrochemical Sensors

by Yali Cui, Yanyuan Zhang, Lin Wang and Yuanqiang Hao

Biosensors 2025, 15(8), 524; https://doi.org/10.3390/bios15080524 - 10 Aug 2025

Abstract

Photoelectrochemical (PEC) sensors have garnered increasing attention due to their high sensitivity, low background signal, and rapid response. The incorporation of hydrogels into PEC platforms has significantly expanded their analytical capabilities by introducing features such as biocompatibility, tunable porosity, antifouling behavior, and mechanical [...] Read more.

Photoelectrochemical (PEC) sensors have garnered increasing attention due to their high sensitivity, low background signal, and rapid response. The incorporation of hydrogels into PEC platforms has significantly expanded their analytical capabilities by introducing features such as biocompatibility, tunable porosity, antifouling behavior, and mechanical flexibility. This review systematically categorizes hydrogel materials into four main types—nucleic acid-based, synthetic polymer, natural polymer, and carbon-based—and summarizes their functional roles in PEC sensors, including structural support, responsive amplification, antifouling interface construction, flexible electrolyte integration, and visual signal output. Representative applications are highlighted, ranging from the detection of ions, small biomolecules, and biomacromolecules to environmental pollutants, photodetectors, and flexible bioelectronic devices. Finally, key challenges—such as improving fabrication scalability, enhancing operational stability, integrating emerging photoactive materials, and advancing bio-inspired system design—are discussed to guide the future development of hydrogel-enhanced PEC sensing technologies. Full article

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

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19 pages, 2087 KiB

Open AccessArticle

Kinematic Monitoring of the Thorax During the Respiratory Cycle Using a Biopolymer-Based Strain Sensor: A Chitosan–Glycerol–Graphite Composite

by María Claudia Rivas Ebner, Emmanuel Ackah, Seong-Wan Kim, Young-Seek Seok and Seung Ho Choi

Biosensors 2025, 15(8), 523; https://doi.org/10.3390/bios15080523 - 9 Aug 2025

Abstract

This study presents the development and the mechanical and clinical characterization of a flexible biodegradable chitosan–glycerol–graphite composite strain sensor for real-time respiratory monitoring, where the main material, chitosan, is derived and extracted from Tenebrio Molitor larvae shells. Chitosan was extracted using a sustainable, [...] Read more.

This study presents the development and the mechanical and clinical characterization of a flexible biodegradable chitosan–glycerol–graphite composite strain sensor for real-time respiratory monitoring, where the main material, chitosan, is derived and extracted from Tenebrio Molitor larvae shells. Chitosan was extracted using a sustainable, low-impact protocol and processed into a stretchable and flexible film through glycerol plasticization and graphite integration, forming a conductive biocomposite. The sensor, fabricated in a straight-line geometry to ensure uniform strain distribution and signal stability, was evaluated for its mechanical and electrical performance under cyclic loading. Results demonstrate linearity, repeatability, and responsiveness to strain variations in the stain sensor during mechanical characterization and performance, ranging from 1 to 15%, with minimal hysteresis and fast recovery times. The device reliably captured respiratory cycles during normal breathing across three different areas of measurement: the sternum, lower ribs, and diaphragm. The strain sensor also identified distinct breathing patterns, including eupnea, tachypnea, bradypnea, apnea, and Kussmaul respiration, showing the capability to sense respiratory cycles during pathological situations. Compared to conventional monitoring systems, the sensor offers superior skin conformity, better adhesion, comfort, and improved signal quality without the need for invasive procedures or complex instrumentation. Its low-cost, biocompatible design holds strong potential for wearable healthcare applications, particularly in continuous respiratory tracking, sleep disorder diagnostics, and home-based patient monitoring. Future work will focus on wireless integration, environmental durability, and clinical validation. Full article

(This article belongs to the Special Issue Multidimensional Nanomaterial-Based Biosensors for Environmental and Healthcare Monitoring)

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13 pages, 5735 KiB

Open AccessArticle

High-Resolution Imaging of Morphological Changes Associated with Apoptosis and Necrosis Using Single-Cell Full-Field Optical Coherence Tomography

by Suyeon Kang, Kyeong Ryeol Kim, Minju Cho, Joonseup Hwang, Joon-Mo Yang, Jun Ki Kim and Woo June Choi

Biosensors 2025, 15(8), 522; https://doi.org/10.3390/bios15080522 - 9 Aug 2025

Abstract

Full-field optical coherence tomography (FF-OCT) is a high-resolution interferometric imaging technique that enables label-free visualization of cellular structural changes. In this study, we employed a custom-built time-domain FF-OCT system to monitor morphological alterations in HeLa cells undergoing doxorubicin-induced apoptosis and ethanol-induced necrosis at [...] Read more.

Full-field optical coherence tomography (FF-OCT) is a high-resolution interferometric imaging technique that enables label-free visualization of cellular structural changes. In this study, we employed a custom-built time-domain FF-OCT system to monitor morphological alterations in HeLa cells undergoing doxorubicin-induced apoptosis and ethanol-induced necrosis at the single-cell level. Apoptotic cells showed characteristic features such as echinoid spine formation, cell contraction, membrane blebbing, and filopodia reorganization. In contrast, necrotic cells exhibited rapid membrane rupture, intracellular content leakage, and abrupt loss of adhesion structure. These dynamic events were visualized using high-resolution tomography and three-dimensional surface topography mapping. Furthermore, FF-OCT-based interference reflection microscopy (IRM)-like imaging effectively highlighted changes in cell–substrate adhesion and cell boundary integrity during the cell death process. Our findings suggest that FF-OCT is a powerful imaging platform for distinguishing cell death pathways and assessing dynamic cellular states, with potential applications in drug toxicity testing, anticancer therapy evaluation, and regenerative medicine. Full article

(This article belongs to the Special Issue Optical Sensors for Biological Detection)

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15 pages, 2370 KiB

Open AccessArticle

Microneedle–Tissue Interaction Across Varying Biological and Mechanical Conditions

by Elham Lori Zoudani, Prabuddha De Saram, Kyle Engel, Nam-Trung Nguyen and Navid Kashaninejad

Biosensors 2025, 15(8), 521; https://doi.org/10.3390/bios15080521 - 9 Aug 2025

Abstract

Microneedle (MN)–tissue interactions play a critical role in the efficiency and reliability of transdermal drug delivery and biosensing, yet their mechanistic understanding remains limited. This study systematically investigates the effects of biological (tissue type and temperature) and mechanical (needle design, material, and insertion [...] Read more.

Microneedle (MN)–tissue interactions play a critical role in the efficiency and reliability of transdermal drug delivery and biosensing, yet their mechanistic understanding remains limited. This study systematically investigates the effects of biological (tissue type and temperature) and mechanical (needle design, material, and insertion velocity) parameters on the performance of microneedle insertion and extraction. Experiments were performed on porcine skin, chicken breast, and agarose gel to represent varying tissue properties. Additionally, the effect of tissue temperature on replicating physiological conditions, such as hypo- and hyperthermia, was evaluated using porcine skin as the sample. A novel conical MN design integrated with surface suction-cup structures was developed to improve tissue adhesion. Mechanical responses were analyzed through force–displacement measurements, evaluating insertion force, extraction force, and relaxation time. Results show that elevated tissue temperature reduces insertion and extraction forces while shortening relaxation times, indicating increased tissue compliance. The suction-cup MNs significantly enhanced needle–tissue adhesion, with the most pronounced effect observed in chicken breast tissue, achieving more than a four-fold increase in extraction force compared to conventional conical needles. These findings provide valuable insights into optimizing the design of MNs for advanced biomedical applications. Full article

(This article belongs to the Special Issue Nano/Micro Biosensors for Biomedical Applications (2nd Edition))

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