Biosensors

16 pages, 5366 KiB

Open AccessArticle

Understanding the Mechanism of Bent DNA Amplifying Sensors Using All-Atom Molecular Dynamics Simulations

by Kaitlin Bullard, Deborah Okyere, Shelbi J. Foster, Asmaa A. Sadoon, Jiali Li, Jingyi Chen and Yong Wang

Biosensors 2025, 15(5), 272; https://doi.org/10.3390/bios15050272 - 26 Apr 2025

Abstract

Bent DNA amplifying sensors were recently developed to amplify and quantify the interactions of DNA with various salts and molecules. However, a thorough quantitative understanding of their mechanism is missing. Here, using all-atom molecular dynamics (MD) simulations, we investigate the behavior and dynamics [...] Read more.

Bent DNA amplifying sensors were recently developed to amplify and quantify the interactions of DNA with various salts and molecules. However, a thorough quantitative understanding of their mechanism is missing. Here, using all-atom molecular dynamics (MD) simulations, we investigate the behavior and dynamics of sharply bent DNA molecules in the absence and presence of Mg²⁺ ions at different concentrations. The simulations show that Mg²⁺ ions reduce the fluctuations of DNA strands, enhance base-pairing, and stabilize bent DNA molecules. The computational results are further verified by both melting curve experiments and ensemble FRET measurements, highlighting the mechanical instability and sensitivity of bent DNA molecules. Full article

(This article belongs to the Special Issue DNA Molecular Engineering-Based Biosensors)

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16 pages, 8827 KiB

Open AccessArticle

One-Pot Colorimetric Nucleic Acid Test Mediated by Silver Nanoparticles for DNA Extraction and Detection

by Seung Kyun Park, Kieu The Loan Trinh and Nae Yoon Lee

Biosensors 2025, 15(5), 271; https://doi.org/10.3390/bios15050271 - 25 Apr 2025

Abstract

This study introduces a one-pot colorimetric nucleic acid test (NAT) platform that integrates silver nanoparticle (AgNP)-based DNA isolation and colorimetric detection of bacterial genes. The NAT platform is comprised with purification and reaction units that enable cell lysis, DNA purification, loop-mediated isothermal amplification [...] Read more.

This study introduces a one-pot colorimetric nucleic acid test (NAT) platform that integrates silver nanoparticle (AgNP)-based DNA isolation and colorimetric detection of bacterial genes. The NAT platform is comprised with purification and reaction units that enable cell lysis, DNA purification, loop-mediated isothermal amplification (LAMP), and colorimetric detection. In the purification unit, polyethyleneimine (PEI)-capped AgNPs were used as cell lysis agents because of their cell-disrupting and antimicrobial properties and were immobilized on a glass fiber membrane for DNA capture and isolation. The reaction unit enabled colorimetric detection of DNA amplicons, achieved by the synthesis of AgNPs on chromatography paper formed via the reduction of silver ions present on the paper, mediated by the use of sodium ascorbate, a reducing agent, present in the LAMP reagent, after the reaction. AgNPs were formed only in the presence of the target amplicons in the positive samples after reaction at 65 °C for 5 min. Bacterial DNA was efficiently extracted using this method, and Enterococcus faecium was detected with a detection limit of 10² CFU/mL. This platform is a promising alternative for rapid and cost-effective nucleic acid testing in resource-limited settings. Full article

(This article belongs to the Special Issue Micro-/Nano Biomedical Point-of-Care Devices)

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16 pages, 9379 KiB

Open AccessArticle

Activation and Expansion of Human T-Cells Using Microfluidic Devices

by Ana Belén Peñaherrera-Pazmiño, Gustavo Rosero, Dario Ruarte, Julia Pinter, Karla Vizuete, Maximiliano Perez, Marie Follo, Betiana Lerner and Roland Mertelsmann

Biosensors 2025, 15(5), 270; https://doi.org/10.3390/bios15050270 - 25 Apr 2025

Abstract

Treatment of cancer patients with autologous T-cells expressing a chimeric antigen receptor (CAR) is one of the most promising therapeutic modalities for hematological malignancy treatment. For this treatment, primary T-cell expansion is needed. Microfluidic technologies can be used to better understand T-cell activation [...] Read more.

Treatment of cancer patients with autologous T-cells expressing a chimeric antigen receptor (CAR) is one of the most promising therapeutic modalities for hematological malignancy treatment. For this treatment, primary T-cell expansion is needed. Microfluidic technologies can be used to better understand T-cell activation and proliferation. Microfluidics have had a meaningful impact in the way experimental biology and biomedical research are approached in general. Furthermore, microfluidic technology allows the generation of large amounts of data and enables the use of image processing for analysis. However, one of the major technical hurdles involved in growing suspension cells under microfluidic conditions is their immobilization, to avoid washing them out of the microfluidic chip during medium renewal. In this work, we use a multilevel microfluidic chip to successfully capture and immobilize suspension cells. Jurkat cells and T-cells are isolated through traps to microscopically track their development and proliferation after activation over a period of 8 days. The T-cell area of four independent microchannels was compared and there is no statistically significant difference between them (ANOVA p-value = 0.976). These multilevel microfluidic chips provide a new method of studying T-cell activation. Full article

(This article belongs to the Special Issue Microfluidics and Organ-on-a-Chip for Disease Modeling and Drug Screening (2nd Edition))

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14 pages, 17614 KiB

Open AccessArticle

Unraveling Charge Transfer Mechanisms in Graphene–Quantum Dot Hybrids for High-Sensitivity Biosensing

by Shinto Mundackal Francis, Hugo Sanabria and Ramakrishna Podila

Biosensors 2025, 15(5), 269; https://doi.org/10.3390/bios15050269 - 24 Apr 2025

Abstract

Colloidal quantum dots (QDs) and graphene hybrids have emerged as promising platforms for optoelectronic and biosensing applications due to their unique photophysical and electronic properties. This study investigates the fundamental mechanism underlying the photoluminescence (PL) quenching and recovery in graphene–QD hybrid systems using [...] Read more.

Colloidal quantum dots (QDs) and graphene hybrids have emerged as promising platforms for optoelectronic and biosensing applications due to their unique photophysical and electronic properties. This study investigates the fundamental mechanism underlying the photoluminescence (PL) quenching and recovery in graphene–QD hybrid systems using single-layer graphene field-effect transistors (SLG-FETs) and time-resolved photoluminescence (TRPL) spectroscopy. We demonstrate that PL quenching and its recovery are primarily driven by charge transfer, as evidenced by an unchanged fluorescence lifetime upon quenching. Density functional theory calculations reveal a significant charge redistribution at the graphene–QD interface, corroborating experimental observations. We also provide a simple analytical quantum mechanical model to differentiate charge transfer-induced PL quenching from resonance energy transfer. Furthermore, we leverage the charge transfer mechanism for ultrasensitive biosensing to detect biomarkers such as immunoglobulin G (IgG) at femtomolar concentrations. The sensor’s electrical response, characterized by systematic shifts in the Dirac point of SLG-FETs, confirms the role of analyte-induced charge modulation in PL recovery. Our findings provide a fundamental framework for designing next-generation graphene-based biosensors with exceptional sensitivity and specificity. Full article

(This article belongs to the Section Nano- and Micro-Technologies in Biosensors)

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Graphical abstract

15 pages, 2844 KiB

Open AccessArticle

Synergistic Signal Amplification via Weak Value Amplification Effect and Sandwich Structure for Highly Sensitive and Specific Real-Time Detection of CA125

by Bei Wang, Yang Xu, Han Li, Zishuo Song, Tian Guan and Yonghong He

Biosensors 2025, 15(5), 268; https://doi.org/10.3390/bios15050268 - 23 Apr 2025

Abstract

Biomolecule detection is pivotal in disease diagnosis. In this study, we present a novel aptamer–antibody sandwich module integrated with an imaging weak measurement system to enhance the sensitivity and specificity of biomolecule detection. The feasibility of this approach is demonstrated using CA125. CA125 [...] Read more.

Biomolecule detection is pivotal in disease diagnosis. In this study, we present a novel aptamer–antibody sandwich module integrated with an imaging weak measurement system to enhance the sensitivity and specificity of biomolecule detection. The feasibility of this approach is demonstrated using CA125. CA125 is a glycoprotein tumor marker widely used for ovarian cancer diagnosis and monitoring, with its level changes closely associated with disease progression. Given its clinical significance, developing highly sensitive and specific CA125 detection methods is crucial for precision medicine. The dual-recognition mechanism combines the high affinity of aptamers and the specificity of antibodies, significantly improving detection performance while utilizing antibodies for signal amplification. In the presence of CA125, the anti-CA125 aptamer immobilized on the chip surface captures the target, which is then specifically bound by the CA125 antibody, forming the aptamer–CA125–antibody complex. This interaction induces a change in the refractive index of the chip surface, which is detected by the imaging weak measurement system and ultimately manifested as a variation in light intensity in the resulting images. The method achieves the highly sensitive detection of CA125 in the 0.01 mU/mL range to 100 U/mL, with preliminary results showing a detection resolution of 3.98 μU/mL and high specificity against non-target proteins. Additionally, detecting CA125 in serum samples further validates the feasibility of the method’s applicability in complex biological matrices. The proposed method offers significant advantages, including high sensitivity, high specificity, label-free, multiplexed detection, low cost, and real-time detection, making it a promising platform for bio-molecule detection with a wide range of applications. Full article

(This article belongs to the Section Biosensors and Healthcare)

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16 pages, 2277 KiB

Open AccessArticle

Simultaneous Trace Analysis of Lead and Cadmium in Drinking Water, Milk, and Honey Samples Through Modified Screen-Printed Electrode

by Fei Wang, Xiao Peng, Ziqian Xiao, Ying Ge, Bilin Tao, Zhaoyong Shou, Yifei Feng, Jing Yuan and Liang Xiao

Biosensors 2025, 15(5), 267; https://doi.org/10.3390/bios15050267 - 23 Apr 2025

Abstract

A composite (N-rGO@ppy) of N-doped reduced graphene oxide (N-rGO) coated with polypyrrole (ppy) particles was successfully synthesized. The incorporation of N-rGO significantly mitigates the aggregation of ppy synthesized in situ, and the doped N atoms improve the conductivity of graphene oxide (GO), thereby [...] Read more.

A composite (N-rGO@ppy) of N-doped reduced graphene oxide (N-rGO) coated with polypyrrole (ppy) particles was successfully synthesized. The incorporation of N-rGO significantly mitigates the aggregation of ppy synthesized in situ, and the doped N atoms improve the conductivity of graphene oxide (GO), thereby enhancing N-rGO@ppy’s redox properties. Firstly, a glassy carbon electrode (GCE) modified with N-rGO@ppy (N-rGO@ppy/GCE) was used in combination with a bismuth film and square-wave anodic stripping voltammetry (SWASV) for the simultaneous trace analysis of Pb²⁺ and Cd²⁺. N-rGO@ppy/GCE exhibited distinct stripping peaks for Pb²⁺ and Cd²⁺, with a linear range of 1 to 500 μg L⁻¹. The limits of detection (LODs) were found to be 0.080 μg L⁻¹ for Pb²⁺ and 0.029 μg L⁻¹ for Cd²⁺, both of which are significantly below the standards set by the World Health Organization (WHO). Subsequently, the same electrochemical sensing strategy was adapted to a more portable screen-printed electrode (SPE) to accommodate the demand for in situ detection. The performance of N-rGO@ppy/SPE for analyzing Pb²⁺ and Cd²⁺ in actual samples, such as drinking water, milk, and honey, showed results consistent with those obtained from conventional graphite furnace atomic absorption spectrometry (GFAAS). Full article

(This article belongs to the Special Issue Electrochemical Sensors and Biosensors for Environmental, Health, and Food Safety Applications (Volume II))

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13 pages, 1853 KiB

Open AccessArticle

Aptamer-Based Microfluidic Assay for In-Field Detection of Salicylic Acid in Botrytis cinerea-Infected Strawberries

by Cristiana Domingues, Rafaela R. Rosa, Rodolfo G. Rodrigues, Ana Margarida Fortes, Virginia Chu and João Pedro Conde

Biosensors 2025, 15(5), 266; https://doi.org/10.3390/bios15050266 - 22 Apr 2025

Abstract

Rapid detection of plant infections is crucial for minimising crop loss and optimising management strategies, particularly in the context of climate change. While traditional diagnostic methods provide precise measurements of phytohormones such as salicylic acid (SA), a key regulator of plant defence responses, [...] Read more.

Rapid detection of plant infections is crucial for minimising crop loss and optimising management strategies, particularly in the context of climate change. While traditional diagnostic methods provide precise measurements of phytohormones such as salicylic acid (SA), a key regulator of plant defence responses, their reliance on bulky equipment and lengthy analysis times limits field applicability. This study presents a microfluidic-based aptamer assay for SA detection, enabling rapid and sensitive fluorescence-based readout from plant samples. A tailored sample pre-treatment protocol was developed and validated with real strawberry samples using HPLC measurements. The assay demonstrated a detection limit ranging from 10⁻⁹ to 10⁻⁶ mg/mL, within the relevant range for early infection diagnosis. The integration of the microfluidic platform with the optimised pre-treatment protocol offers a portable, cost-effective solution for on-site phytohormone analysis, providing a valuable tool for early infection detection and improved crop management. Full article

(This article belongs to the Special Issue Microfluidic Devices for Biological Sample Analysis)

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15 pages, 3804 KiB

Open AccessReview

Current Trends in In Vitro Diagnostics Using Surface-Enhanced Raman Scattering in Translational Biomedical Research

by Sitansu Sekhar Nanda, Dae-Gyeom Park and Dong Kee Yi

Biosensors 2025, 15(5), 265; https://doi.org/10.3390/bios15050265 - 22 Apr 2025

Abstract

Immunoassays using surface-enhanced Raman scattering (SERS) are prosperous in disease diagnosis due to their excellent multiplexing ability, high sensitivity, and large dynamic range. Given the recent advancements in SERS immunoassays, this work provides a comprehensive overview, from fundamental principles to practical applications. An [...] Read more.

Immunoassays using surface-enhanced Raman scattering (SERS) are prosperous in disease diagnosis due to their excellent multiplexing ability, high sensitivity, and large dynamic range. Given the recent advancements in SERS immunoassays, this work provides a comprehensive overview, from fundamental principles to practical applications. An mRNA sensor utilizing Raman spectroscopy is a detection method that leverages the unique vibrational characteristics of mRNA molecules to identify and quantify their presence in a sample, often achieved through a technique called SERS, where specially designed nanoparticles amplify the Raman signal, allowing for the highly sensitive detection of even small amounts of mRNA. This review analyzes SERS assays used to detect RNA biomarkers, which show promise in cancer diagnostics and are being actively studied clinically. To selectively detect a specific mRNA sequence, a probe molecule (e.g., a DNA oligonucleotide complementary to the target mRNA) is attached to the SERS substrate, allowing the target mRNA to hybridize and generate a detectable Raman signal upon binding. Thus, the discussion includes proposals to enhance SERS immunoassay performance, along with future challenges and perspectives, offering concise, valid guidelines for platform selection based on application. Full article

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

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10 pages, 4315 KiB

Open AccessArticle

Point-of-Care NSE Biosensor for Objective Assessment of Stroke Risk

by Cheng Hsu Chen, Erick Wang, Tsung-Han Lee, Cheng-Chieh Huang, Chun-San Tai, Yan-Ren Lin and Wen-Liang Chen

Biosensors 2025, 15(4), 264; https://doi.org/10.3390/bios15040264 - 20 Apr 2025

Abstract

The rapid identification of stroke is critical to improving stroke patient outcomes. Existing protocols for assessing the risk of stroke are subjective and may be further complicated by nonspecific symptoms, increasing the risk of misdiagnosis. Neuron-specific enolase (NSE) has emerged as a promising [...] Read more.

The rapid identification of stroke is critical to improving stroke patient outcomes. Existing protocols for assessing the risk of stroke are subjective and may be further complicated by nonspecific symptoms, increasing the risk of misdiagnosis. Neuron-specific enolase (NSE) has emerged as a promising stroke biomarker. However, current detection methods such as the electrochemiluminescence immunoassay (ECLIA) are time-consuming and costly. In this research, we developed an electrochemical biosensor for the rapid quantification of NSE in whole blood. Mouse stroke models were established, and blood samples collected were analyzed using both hospital-standard ECLIA as well as the biosensor. The biosensor limit of detection was 1.15 ng/mL. NSE measurements were highly correlated between the two methods and were obtained in 5 min using 20 μL of unprocessed whole blood samples. Notably, the biosensor could accurately quantify elevated blood NSE blood that was associated with more severe stroke. Our results demonstrate the utility of the proposed biosensor in pre-hospital settings. Combined with existing stroke assessment methods, the biosensor may enable emergency personnel to identify stroke risk with greater accuracy to optimize the chances of receiving necessary treatment within the effective window. Full article

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

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16 pages, 1263 KiB

Open AccessArticle

Smart Prussian Blue Analog Decorated with Zinc Oxide Nanohybrid: Fluorescent Sensing and Sustainability of Sunset Yellow in Food and Environment

by Hany A. Batakoushy, Amr K. A. Bass, Hassanien Gomaa, Sami El Deeb and Adel Ehab Ibrahim

Biosensors 2025, 15(4), 263; https://doi.org/10.3390/bios15040263 - 20 Apr 2025

Abstract

In the current study, the Prussian blue analog decorated with zinc oxide (PBA@ZnO) was produced using a simple chemical co-precipitation method. The nanohybrid was examined using XRD, EDX, SEM, and TEM techniques, where it exhibited a polycrystalline structure with highly intense broadening peaks. [...] Read more.

In the current study, the Prussian blue analog decorated with zinc oxide (PBA@ZnO) was produced using a simple chemical co-precipitation method. The nanohybrid was examined using XRD, EDX, SEM, and TEM techniques, where it exhibited a polycrystalline structure with highly intense broadening peaks. The surface morphology was observed as thin nanosheets decorated with tiny spheres. Following excitation at 360 nm, the fluorescence spectra of PBA@ZnO showed fluorescence emission at 455 nm. The developed PBA@ZnO was used to qualitatively and quantitatively assess sunset yellow (SY), where its native fluorescence was selectively quenched as SY concentrations increased. For the first time, PBA@ZnO was used as a turn-off nano-sensor for the spectrofluorimetric measurement of SY. The method’s markable sensitivity was demonstrated within an SY linearity range of 50–500 ng/mL, where the limit of detection was calculated as 9.77 ng/mL. Real sample analysis in the food industry, including samples from real food, soft drinks, and sun cream, was made possible by the detection of tiny amounts of SY. Analytical Greenness (AGREE), AGREEprep, and the complementing Green Analytical Procedure Index (Complex MoGAPI) were used to illustrate the new approach’s exceptional eco-friendliness and greenness. The RGB 12 algorithm worked to demonstrate that the suggested approach is less costly, more environmentally friendly, more sustainable, analytically sound, and whiter than the ones that were previously published. In accordance with ICH principles, the suggested method was validated. This approach offers a promising way to rapidly and accurately identify and measure SY in the food industry, helping to guarantee food safety and maintain the health of customers. Full article

(This article belongs to the Special Issue Innovative Biosensing Technologies for Sustainable Healthcare)

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15 pages, 3266 KiB

Open AccessArticle

Distinct Neural Activities in Hippocampal Subregions Revealed Using a High-Performance Wireless Microsystem with PtNPs/PEDOT:PSS-Enhanced Microelectrode Arrays

by Peiyao Jiao, Qianli Jia, Shuqi Li, Jin Shan, Wei Xu, Yu Wang, Yu Liu, Mingchuan Wang, Yilin Song, Yulian Zhang, Yanbing Yu, Mixia Wang and Xinxia Cai

Biosensors 2025, 15(4), 262; https://doi.org/10.3390/bios15040262 - 18 Apr 2025

Abstract

Wireless microsystems for neural signal recording have emerged as a solution to overcome the limitations of tethered systems, which restrict the mobility of subjects and introduce noise interference. However, existing microsystems often face data throughput, signal processing, and long-distance wireless transmission challenges. This [...] Read more.

Wireless microsystems for neural signal recording have emerged as a solution to overcome the limitations of tethered systems, which restrict the mobility of subjects and introduce noise interference. However, existing microsystems often face data throughput, signal processing, and long-distance wireless transmission challenges. This study presents a high-performance wireless microsystem capable of 32-channel, 30 kHz real-time recording, featuring Field Programmable Gate Array (FPGA)-based signal processing to reduce transmission load. The microsystem is integrated with platinum nanoparticles/poly (3,4-ethylenedioxythiophene) polystyrene sulfonate-enhanced microelectrode arrays for improved signal quality. A custom NeuroWireless platform was developed for seamless data reception and storage. Experimental validation in rats demonstrated the microsystem’s ability to detect spikes and local field potentials from the hippocampal CA1 and CA2 subregions. Comparative analysis of the neural signals revealed distinct activity patterns between these subregions. The wireless microsystem achieves high accuracy and throughput over distances up to 30 m, demonstrating its resilience and potential for neuroscience research. This work provides a compact, adaptable solution for multi-channel neural signal detection and offers a foundation for future applications in brain–computer interfaces. Full article

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

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11 pages, 3253 KiB

Open AccessArticle

Development of a Smartphone-Linked Immunosensing System for Oxytocin Determination

by Miku Sarubo, Yoka Suzuki, Yuka Numazaki and Hiroyuki Kudo

Biosensors 2025, 15(4), 261; https://doi.org/10.3390/bios15040261 - 18 Apr 2025

Abstract

We report an optical immunosensing system for oxytocin (OXT) based on image analysis of color reactions in an enzyme-linked immunosorbent assay (ELISA). We employed a miniaturized optical immunosensing unit that was functionally connected to an LED and a smartphone camera. Our system measures [...] Read more.

We report an optical immunosensing system for oxytocin (OXT) based on image analysis of color reactions in an enzyme-linked immunosorbent assay (ELISA). We employed a miniaturized optical immunosensing unit that was functionally connected to an LED and a smartphone camera. Our system measures OXT levels using a metric called the RGBscore, which is derived from the red, green, and blue (RGB) information in the captured images. By calculating the RGBscore regressively using the brute-force method, this approach can be applied to smartphones with various CMOS image sensors and firmware. The lower detection limit was determined to be 5.26 pg/mL, and the measurement results showed a higher correlation (r = 0.972) with those obtained from conventional ELISA. These results suggest the potential for its application in a simplified health management system for individuals. Full article

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

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16 pages, 4048 KiB

Open AccessReview

Challenges of Using Whole-Cell Bioreporter for Assessment of Heavy Metal Bioavailability in Soil/Sediment

by Shanshan Bai, Zhipeng Liu, Jiazhi Xu, Yongshuo Li, Zirun Zhang, Zefeng Huang, Williamson Gustave, Boling Li, Xiaokai Zhang and Feng He

Biosensors 2025, 15(4), 260; https://doi.org/10.3390/bios15040260 - 18 Apr 2025

Abstract

Soil and sediment contamination with heavy metals (HMs) is a critical environmental issue, posing significant risks to both ecosystems and human health. Whole-cell bioreporter (WCB) technology offers a promising alternative to traditional detection techniques due to its ability to rapidly assess the bioavailability [...] Read more.

Soil and sediment contamination with heavy metals (HMs) is a critical environmental issue, posing significant risks to both ecosystems and human health. Whole-cell bioreporter (WCB) technology offers a promising alternative to traditional detection techniques due to its ability to rapidly assess the bioavailability of pollutants. Specifically, lights-on WCBs quantify pollutant bioavailability by measuring bioluminescence or fluorescence in response to pollutant exposure, demonstrating comparable accuracy to traditional methods for quantitative pollutant detection. However, when applied to soil and sediment, the signal intensity directly measured by WCBs is often attenuated due to interference from solid particles, leading to the underestimation of bioavailability. Currently, no standardized method exists to correct for this signal attenuation. This review provides a critical analysis of the benefits and limitations of traditional detection methods and WCB technology in assessing HM bioavailability in soil and sediment. Based on the approaches used to address WCB signal attenuation, correction methods are categorized into four types: the assumed negligible method, the non-inducible luminescent control method, the addition of a standard to a reference soil, and a pre-exposure bioreporter. We provide a comprehensive analysis of each method’s applicability, benefits, and limitations. Lastly, potential future directions for advancing WCB technology are proposed. This review seeks to establish a theoretical foundation for researchers and environmental professionals utilizing WCB technology for pollutant bioavailability assessment in soil and sediment. Full article

(This article belongs to the Special Issue Application of Biosensors in Environmental Monitoring)

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16 pages, 4084 KiB

Open AccessArticle

Movement Recognition and Muscle Force Estimation of Wrist Based on Electromyographic Signals of Forearm

by Leiyu Zhang, Zhenxing Jiao, Yongzhen Li and Yawei Chang

Biosensors 2025, 15(4), 259; https://doi.org/10.3390/bios15040259 - 17 Apr 2025

Abstract

To enhance wrist impairment rehabilitation efficiency, self-rehabilitation training using healthy-side forearm sEMG was introduced, improving patient engagement and proprioception. A sEMG-based movement recognition and muscle force estimation algorithm was proposed to transmit the estimated results to a wrist rehabilitation robot. Dominant eigenvalues of [...] Read more.

To enhance wrist impairment rehabilitation efficiency, self-rehabilitation training using healthy-side forearm sEMG was introduced, improving patient engagement and proprioception. A sEMG-based movement recognition and muscle force estimation algorithm was proposed to transmit the estimated results to a wrist rehabilitation robot. Dominant eigenvalues of raw forearm EMG signals were selected to construct a movement recognition model that included a BPNN, a voting decision, and an intensified algorithm. An experimental platform for muscle force estimation was established to measure sEMG under various loads. The linear fitting was performed between mean absolute values (MAVs) and external loads to derive static muscle force estimation models. A dynamic muscle force estimation model was established through linear fitting average MAVs. Volunteers wore EMG sensors and performed six typical movements to complete the verification experiment. The average accuracy of only BPNN was 90.7%, and after the addition of the voting decision and intensified algorithm, it was improved to 98.7%. In the resistance training, the measured and estimated muscle forces exhibited similar trends, with RMSE of 4.2 N for flexion/extension and 5.8 N for ulnar/radial deviation. Under two different speeds and loads, the theoretical and estimated values of dynamic muscle forces showed similar trends with almost no phase difference, and the estimation accuracy was better during flexion movements compared to radial deviations. The proposed algorithms had strong versatility and practicality, aiming to realize the self-rehabilitation trainings of patients. Full article

(This article belongs to the Section Wearable Biosensors)

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15 pages, 3390 KiB

Open AccessArticle

Achievement of 15-Minute Adaptive PCR Benchmark with 1370 nm Laser Heating

by Nicholas Spurlock, Rosana Alfaro, William E. Gabella, Kunal Chugh, Megan E. Pask, Franz Baudenbacher and Frederick R. Haselton

Biosensors 2025, 15(4), 258; https://doi.org/10.3390/bios15040258 - 17 Apr 2025

Abstract

In low-resource and point-of-care settings, traditional PCR often faces challenges of poor sample preparation, adverse environmental conditions, and long assay times. We have previously described a laboratory-based instrument to achieve “adaptive” PCR, a PCR thermocycling control system that replaces preset cycling times and [...] Read more.

In low-resource and point-of-care settings, traditional PCR often faces challenges of poor sample preparation, adverse environmental conditions, and long assay times. We have previously described a laboratory-based instrument to achieve “adaptive” PCR, a PCR thermocycling control system that replaces preset cycling times and temperatures with the optical monitoring of added L-DNA stereoisomers matching the sequences of the reaction primers and target. These L-DNA biosensors directly monitor DNA hybridization, compensating for ambient environmental conditions and poor sample preparation. This report describes instrument simplifications and a comparative evaluation of both direct photothermal and plasmonic laser heating to reduce the assay time to 15 min. Instrument performance was assessed using a split sample design to compare reaction performances of 1370 and 808 nm adaptive PCR heating modalities to a standard PCR instrument. Both the novel 1370 nm direct heating and the 808 nm plasmonic method achieved target amplification similar to the traditional PCR system within 15 min. However, a major disadvantage of 808 nm heating was nanorod optical interference that reduced the fluorescence signal from PCR probes and optical cycling components. Further characterization of the 1370 nm direct heating method found comparable limits of detection of 10⁰ copies/µL and reaction efficiencies of approximately 2 for both the 1370 nm system and the traditional PCR instrument. These results suggest that a field-deployable PCR instrument design incorporating both adaptive optical control and 1370 nm laser heating can achieve 15 min sample assay times without sacrificing analytical sensitivity. Full article

(This article belongs to the Special Issue Feature Paper in Biosensor and Bioelectronic Devices 2025)

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24 pages, 1661 KiB

Open AccessReview

Innovative Methodologies for the Early Detection of Breast Cancer: A Review Categorized by Target Biological Samples

by Antonella Grasso, Vittorio Altomare, Giulia Fiorini, Alessandro Zompanti, Giorgio Pennazza and Marco Santonico

Biosensors 2025, 15(4), 257; https://doi.org/10.3390/bios15040257 - 17 Apr 2025

Abstract

Innovative biosensor technologies are revolutionizing cancer detection by offering non-invasive, sensitive, and rapid diagnostic tools, addressing the limitations of conventional screening. Non-invasive samples like breath, saliva, urine, and sweat, analyzed using advanced technologies like electronic nose systems and AI, show promise for early [...] Read more.

Innovative biosensor technologies are revolutionizing cancer detection by offering non-invasive, sensitive, and rapid diagnostic tools, addressing the limitations of conventional screening. Non-invasive samples like breath, saliva, urine, and sweat, analyzed using advanced technologies like electronic nose systems and AI, show promise for early detection and frequent monitoring, though validation is needed. AI integration enhances data analysis and personalization. While blood-based methods remain the gold standard, combining them with less invasive sample types like saliva or sweat, and using sensitive techniques, is a promising direction. Conventional methods (mammography, MRI, etc.) offer proven efficacy, but are costly and invasive. Innovative methods using biosensors offer reduced infrastructure needs, lower costs, and patient-friendly sampling. However, challenges remain in validation, standardization, and low biomarker concentrations. Integrating both methodologies could create a comprehensive framework, combining reliability with accessibility. Future research should focus on robust biosensor development, standardization, expanding application to other cancers, exploring less-studied samples like sweat, and improving affordability for wider adoption, especially in resource-limited settings. The future lies in integrating diverse approaches for more sensitive, specific, and patient-friendly screening, improving early detection and outcomes. Full article

(This article belongs to the Special Issue Innovative Strategies for Cancer Biosensing)

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21 pages, 9099 KiB

Open AccessArticle

Polymerized Alizarin Red–Inorganic Hybrid Nanoarchitecture (PARIHN) as a Novel Fluorogenic Label for the Immunosorbent Assay of COVID-19

by Fatema Kaladari, Mahmoud El-Maghrabey, Naoya Kishikawa, Rania El-Shaheny and Naotaka Kuroda

Biosensors 2025, 15(4), 256; https://doi.org/10.3390/bios15040256 - 16 Apr 2025

Abstract

This study seeks to develop and implement a non-enzymatic fluorescent labeling for immunoassay and immunochromatographic assay (ICAs) targeting SARS-CoV-2, to meet the extensive interest and need for effective COVID-19 diagnosis. In this manuscript, we delineate the development, synthesis, and evaluation of a novel [...] Read more.

This study seeks to develop and implement a non-enzymatic fluorescent labeling for immunoassay and immunochromatographic assay (ICAs) targeting SARS-CoV-2, to meet the extensive interest and need for effective COVID-19 diagnosis. In this manuscript, we delineate the development, synthesis, and evaluation of a novel quinone polymer zinc hybrid nanoarchitecture, referred to as polymerized alizarin red–inorganic hybrid nanoarchitecture (PARIHN), which integrates an antibody for direct use in fluorescent immunoassays, offering enhanced sensitivity, reduced costs, and improved environmental sustainability. The designed nanoarchitecture can enhance the sensitivity of the immunoassay and enable rapid results without the complexities associated with enzymes, such as their low stability and high cost. At first, a chitosan–alizarin polymer was synthesized utilizing quinone–chitosan conjugation chemistry (QCCC). Then, the chitosan–alizarin polymer was embedded with the detection antibody using zinc ion, forming PARIHN, which was proven to be a stable label with the ability to enhance the assay stability and sensitivity of the immunoassay. PARIHN can react with phenylboronic acid (PBA) or boric acid through its alizarin content to produce fluorescence signals with an LOD of 15.9 and 2.6 pm for PBA and boric acid, respectively, which is the first use of a boric acid derivative in signal generation in the immunoassay. Furthermore, PARIHN demonstrated high practicality in detecting SARS-CoV-2 nucleoprotein in fluorescence (PBA and boric acid) systems with an LOD of 0.76 and 10.85 pm, respectively. Furthermore, owing to the high brightness of our PARIHN fluorogenic reaction, our labeling approach was extended to immunochromatographic assays for SARS-CoV-2 with high sensitivity down to 9.45 pg/mL. Full article

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

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27 pages, 7099 KiB

Open AccessArticle

Diabetes: Non-Invasive Blood Glucose Monitoring Using Federated Learning with Biosensor Signals

by Narmatha Chellamani, Saleh Ali Albelwi, Manimurugan Shanmuganathan, Palanisamy Amirthalingam and Anand Paul

Biosensors 2025, 15(4), 255; https://doi.org/10.3390/bios15040255 - 16 Apr 2025

Abstract

Diabetes is a growing global health concern, affecting millions and leading to severe complications if not properly managed. The primary challenge in diabetes management is maintaining blood glucose levels (BGLs) within a safe range to prevent complications such as renal failure, cardiovascular disease, [...] Read more.

Diabetes is a growing global health concern, affecting millions and leading to severe complications if not properly managed. The primary challenge in diabetes management is maintaining blood glucose levels (BGLs) within a safe range to prevent complications such as renal failure, cardiovascular disease, and neuropathy. Traditional methods, such as finger-prick testing, often result in low patient adherence due to discomfort, invasiveness, and inconvenience. Consequently, there is an increasing need for non-invasive techniques that provide accurate BGL measurements. Photoplethysmography (PPG), a photosensitive method that detects blood volume variations, has shown promise for non-invasive glucose monitoring. Deep neural networks (DNNs) applied to PPG signals can predict BGLs with high accuracy. However, training DNN models requires large and diverse datasets, which are typically distributed across multiple healthcare institutions. Privacy concerns and regulatory restrictions further limit data sharing, making conventional centralized machine learning (ML) approaches less effective. To address these challenges, this study proposes a federated learning (FL)-based solution that enables multiple healthcare organizations to collaboratively train a global model without sharing raw patient data, thereby enhancing model performance while ensuring data privacy and security. In the data preprocessing stage, continuous wavelet transform (CWT) is applied to smooth PPG signals and remove baseline drift. Adaptive cycle-based segmentation (ACBS) is then used for signal segmentation, followed by particle swarm optimization (PSO) for feature selection, optimizing classification accuracy. The proposed system was evaluated on diverse datasets, including VitalDB and MUST, under various conditions with data collected during surgery and anesthesia. The model achieved a root mean square error (RMSE) of 19.1 mg/dL, demonstrating superior predictive accuracy. Clarke error grid analysis (CEGA) confirmed the model’s clinical reliability, with 99.31% of predictions falling within clinically acceptable limits. The FL-based approach outperformed conventional deep learning models, making it a promising method for non-invasive, privacy-preserving glucose monitoring. Full article

(This article belongs to the Section Biosensors and Healthcare)

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14 pages, 4011 KiB

Open AccessArticle

The Optimization of a T-Cell Resonator: Towards Highly Sensitive Photoacoustic Spectroscopy for Noninvasive Blood Glucose Detection

by Thasin Mohammad Zaman, Md Rejvi Kaysir, Shazzad Rassel and Dayan Ban

Biosensors 2025, 15(4), 254; https://doi.org/10.3390/bios15040254 - 16 Apr 2025

Abstract

Noninvasive blood glucose monitoring is crucial for diabetes management, and photoacoustic spectroscopy (PAS) offers a promising solution by detecting glucose levels through human skin. However, weak acoustic signals in PAS systems require optimized resonator designs for enhanced detection sensitivity. Designing such resonators physically [...] Read more.

Noninvasive blood glucose monitoring is crucial for diabetes management, and photoacoustic spectroscopy (PAS) offers a promising solution by detecting glucose levels through human skin. However, weak acoustic signals in PAS systems require optimized resonator designs for enhanced detection sensitivity. Designing such resonators physically is complex, requiring the precise identification of critical parameters before practical implementation. This study focused on optimizing a T-shaped photoacoustic resonator using finite element modeling in a COMSOL Multiphysics environment. By systematically varying the geometric design parameters of the T-cell resonator, a maximum increase in the pressure amplitude of 12.76 times with a quality factor (Q-factor) of 47.5 was achieved compared to the previously designed reference acoustic resonator. This study took a significant step forward by identifying key geometric parameters that influence resonator performance, paving the way for more sensitive and reliable noninvasive glucose monitoring systems. Full article

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

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