Biosensors

13 pages, 1932 KB

Open AccessArticle

Universal Platform Based on Carbon Nanotubes Functionalised with Carboxylic Acid Groups for Multi-Analyte Enzymatic Biosensing

by Edmundas Lukoševičius, Julija Kravčenko, Grėta Mikėnaitė, Augustas Markevičius and Gintautas Bagdžiūnas

Biosensors 2025, 15(10), 686; https://doi.org/10.3390/bios15100686 - 10 Oct 2025

Abstract

This work presents the development of carbon nanotubes functionalised with carboxylic acid groups (CNT-COOH) as an oxygen-sensitive electrochemical platform for parallel multi-analyte enzymatic biosensing. The platform was constructed by depositing carboxylic-acid-functionalised single-walled carbon nanotubes covalently onto nanostructured gold electrodes modified with a self-assembled [...] Read more.

This work presents the development of carbon nanotubes functionalised with carboxylic acid groups (CNT-COOH) as an oxygen-sensitive electrochemical platform for parallel multi-analyte enzymatic biosensing. The platform was constructed by depositing carboxylic-acid-functionalised single-walled carbon nanotubes covalently onto nanostructured gold electrodes modified with a self-assembled monolayer of 4-aminothiophenol. Atomic force microscopy characterization revealed that the nanotubes attached via their ends to the surface and had a predominantly horizontal orientation. Glucose oxidase, lactate oxidase, glutamate oxidase, and tyrosinase were immobilised onto the electrodes to create selective biosensor for lactate, glucose, glutamate, and dopamine, respectively. A key finding is that incorporating catalase significantly extends the linear detection range for analytes by mitigating the accumulation of hydrogen peroxide. The resulting multifunctional biosensor demonstrated its capability for the simultaneous and independent measurement of glucose, lactate as the key bioanalytes under uniform conditions in blood plasma samples, highlighting its potential for applications in health and food technologies. Full article

(This article belongs to the Topic Applications of Nanomaterials in Biosensing: Current Trends and Future Prospects)

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15 pages, 2897 KB

Open AccessArticle

A Molecularly Imprinted Membrane for High-Density Lipoprotein Extraction in Point-of-Care Testing

by Gian Luca de Gregorio, Denis Prim, Alberto Zavattoni, Italo Mottini, Daniele Pezzoli, Federico Roveda, Marc E. Pfeifer and Jean-Manuel Segura

Biosensors 2025, 15(10), 685; https://doi.org/10.3390/bios15100685 - 10 Oct 2025

Abstract

Cholesterol blood levels in low-density lipoproteins (LDLs) are a key parameter for assessing the risk of cardiovascular diseases. Direct quantification of LDL cholesterol at the point of care would be possible if all other lipoproteins, particularly the high-density lipoproteins (HDLs), could be removed [...] Read more.

Cholesterol blood levels in low-density lipoproteins (LDLs) are a key parameter for assessing the risk of cardiovascular diseases. Direct quantification of LDL cholesterol at the point of care would be possible if all other lipoproteins, particularly the high-density lipoproteins (HDLs), could be removed prior to measurement. Here, we investigated whether a molecularly imprinted membrane (MIM) could be used for the solid-phase affinity extraction (SPAE) of HDL in a paper-based lateral flow test. Samples traveled by capillarity through the MIM before reaching a detection zone where LDL cholesterol was quantified enzymatically. MIMs were produced by impregnation of the membrane with a dispersion of molecularly imprinted polymers (MIPs) selective for HDL. MIPs were synthesized using precipitation polymerization and exhibited good selectivity for HDL compared with LDL and an uptake capacity of 5.0–7.0 µg of HDL-C/mg of MIP. The MIM enabled the removal of HDL with an efficiency of typically 68%. However, quantification of LDL cholesterol suffered from strong non-specific binding of LDL, likely due to its inherent colloidal instability. Overall, our results highlight the challenges associated with SPAE of colloidal particles. Furthermore, our study demonstrates a novel, efficient, and potentially generic modality to integrate SPAE into paper-based POC diagnostic tests. Full article

(This article belongs to the Special Issue Biosensing and Diagnosis—2nd Edition)

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56 pages, 7355 KB

Open AccessReview

Carbon Nanomaterial-Based Electrochemical Biosensors for Alzheimer’s Disease Biomarkers: Progress, Challenges, and Future Perspectives

by Berfin Şak, Helena B. A. Sousa and João A. V. Prior

Biosensors 2025, 15(10), 684; https://doi.org/10.3390/bios15100684 - 9 Oct 2025

Abstract

Alzheimer’s disease (AD) requires early and accurate identification of affected brain regions, which can be achieved through the detection of specific biomarkers to enable timely intervention. Carbon nanomaterials (CNMs), including graphene derivatives, carbon nanotubes, graphitic carbon nitride, carbon black, fullerenes, and carbon dots, [...] Read more.

Alzheimer’s disease (AD) requires early and accurate identification of affected brain regions, which can be achieved through the detection of specific biomarkers to enable timely intervention. Carbon nanomaterials (CNMs), including graphene derivatives, carbon nanotubes, graphitic carbon nitride, carbon black, fullerenes, and carbon dots, offer high conductivity, large electroactive surface area, and versatile surface chemistry that enhance biosensor performance. While such properties benefit a wide range of transduction principles (e.g., electrochemical, optical, and plasmonic), this review focuses on their role in electrochemical biosensors. This review summarizes CNM-based electrochemical platforms reported from 2020 to mid-2025, employing aptamers, antibodies, and molecularly imprinted polymers for AD biomarker detection. Covered topics include fabrication strategies, transduction formats, analytical performance in complex matrices, and validation. Reported devices achieve limits of detection from the femtomolar to picogram per milliliter range, with linear ranges typically spanning 2–3 orders of magnitude (e.g., from femtomolar to picomolar, or from picogram to nanogram per milliliter levels). They exhibit high selectivity against common interferents such as BSA, glucose, uric acid, ascorbic acid, dopamine, and non-target peptides, along with growing capabilities for multiplexing and portable operation. Remaining challenges include complex fabrication, limited long-term stability and reproducibility data, scarce clinical cohort testing, and sustainability issues. Opportunities for scalable production and integration into point-of-care workflows are outlined. Full article

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

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26 pages, 3265 KB

Open AccessReview

Kinetics and Activation Strategies in Toehold-Mediated and Toehold-Free DNA Strand Displacement

by Yuqin Wu, Mingguang Jin, Cuizheng Peng, Guan Alex Wang and Feng Li

Biosensors 2025, 15(10), 683; https://doi.org/10.3390/bios15100683 - 9 Oct 2025

Abstract

Nucleic acid strand displacement reactions (SDRs) are fundamental building blocks of dynamic DNA nanotechnology. A detailed understanding of their kinetics is crucial for designing efficient sequences and regulating reaction networks with applications in biosensing, synthetic biology, biocomputing, and medical diagnostics. Since the development [...] Read more.

Nucleic acid strand displacement reactions (SDRs) are fundamental building blocks of dynamic DNA nanotechnology. A detailed understanding of their kinetics is crucial for designing efficient sequences and regulating reaction networks with applications in biosensing, synthetic biology, biocomputing, and medical diagnostics. Since the development of toehold-mediated strand displacement, researchers have devised many strategies to adjust reaction kinetics. These efforts have expanded the available tools in DNA nanotechnology. This review summarizes the basic principles and recent advances in activation strategies, emphasizing the role of strand proximity as a central driving force. Proximity-based approaches include toehold docking, associative toeholds, remote toeholds, and allosteric designs, as well as strategies that operate without explicit toehold motifs. These methods enable flexible and scalable construction of DNA reaction networks. We further discuss how combining different activation and kinetic control approaches gives rise to dynamic networks with complex and dissipative behaviors, providing new directions for DNA-based nanotechnology. Full article

(This article belongs to the Special Issue Aptamer-Based Biosensors for Point-of-Care Diagnostics)

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40 pages, 2958 KB

Open AccessReview

Multiplexed Optical Nanobiosensing Technologies for Disease Biomarker Detection

by Pureum Kim, Min Yu Choi, Yubeen Lee, Ki-Bum Lee and Jin-Ha Choi

Biosensors 2025, 15(10), 682; https://doi.org/10.3390/bios15100682 - 9 Oct 2025

Abstract

Most biomarkers exhibit abnormal expression in more than one disease, making conventional single-biomarker detection strategies prone to false-negative results. Detecting multiple biomarkers associated with a single disease can therefore substantially improve diagnostic accuracy. Accordingly, recent research has focused on precise multiplex detection, leading [...] Read more.

Most biomarkers exhibit abnormal expression in more than one disease, making conventional single-biomarker detection strategies prone to false-negative results. Detecting multiple biomarkers associated with a single disease can therefore substantially improve diagnostic accuracy. Accordingly, recent research has focused on precise multiplex detection, leading to the development of sensors employing various readout methods, including electrochemical, fluorescence, Raman, and colorimetric approaches. This review focuses on optical sensing applications, such as fluorescence, Raman spectroscopy, and colorimetry, which offer rapid and straightforward detection and are well suited for point-of-care testing (POCT). These optical sensors exploit nanoscale phenomena derived from the intrinsic properties of nanomaterials, including metal-enhanced fluorescence (MEF), Förster resonance energy transfer (FRET), and surface-enhanced Raman scattering (SERS), which can be tailored through modifications in material type and structure. We summarize the types and properties of commonly used nanomaterials, including plasmonic and carbon-based nanoparticles, and provide a comprehensive overview of recent advances in multiplex biomarker detection. Furthermore, we address the potential of these nanosensors for clinical translation and POCT applications, highlighting their relevance for next-generation disease diagnostic platforms. Full article

(This article belongs to the Special Issue Nanomaterial-Based Biosensors for Point-of-Care Testing)

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12 pages, 1745 KB

Open AccessArticle

Construction and Characterization of a Novel Direct Electron Transfer Type Enzymatic Sensor Using Spermidine Dehydrogenase

by Sheng Tong, Yuki Yaegashi, Mao Fukushi, Takumi Yanase, Junko Okuda-Shimazaki, Ryutaro Asano, Kazunori Ikebukuro, Madoka Nagata, Koji Sode and Wakako Tsugawa

Biosensors 2025, 15(10), 681; https://doi.org/10.3390/bios15100681 - 9 Oct 2025

Abstract

This study reports on the direct electron transfer (DET) ability of the enzyme spermidine dehydrogenase (SpDH) and its use in a DET-type enzymatic sensor for detecting spermine. SpDH was found to exhibit internal electron transfer from its cofactor, flavin adenine dinucleotide (FAD), to [...] Read more.

This study reports on the direct electron transfer (DET) ability of the enzyme spermidine dehydrogenase (SpDH) and its use in a DET-type enzymatic sensor for detecting spermine. SpDH was found to exhibit internal electron transfer from its cofactor, flavin adenine dinucleotide (FAD), to heme b. This was confirmed by observing the heme b-derived reduction peak at 560 nm in the presence of spermine, the substrate. SpDH was immobilized on a gold electrode via a dithiobis (succinimidyl hexanoate) self-assembled monolayer. The cyclic voltammetry analysis of the SpDH-immobilized gold electrode revealed an increased oxidation current in the presence of 0.1 mM spermine with an onset potential of −0.14 V vs. Ag/AgCl in the absence of an additional external electron acceptor. This result confirmed that SpDH is capable of DET. Chronoamperometric analyses were conducted using an SpDH-immobilized gold electrode with spermine as the substrate under a 0 V oxidation potential vs. Ag/AgCl using an artificial saliva matrix containing 10 µM ascorbic acid and 100 µM uric acid. The sensor exhibited good linear correlation between the current increase and spermine concentration from 0.2 to 2.0 µM, with a limit of detection of 0.084 µM, which encompasses the physiologically relevant spermine concentration found in the saliva. Primary structure alignments and 3D structure predictions revealed that all SpDH homologs possess two conserved histidine residues in the same location on the surface as the heme b ligand of SpDH. This indicates their potential for DET-ability with an electrode. Full article

(This article belongs to the Special Issue New Trends in Electrochemical Biosensors for Healthcare and Environmental Monitoring)

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19 pages, 5194 KB

Open AccessArticle

Automatic Removal of Physiological Artifacts in OPM-MEG: A Framework of Channel Attention Mechanism Based on Magnetic Reference Signal

by Yong Li, Dawei Wang, Hao Lu, Yuyu Ma, Chunhui Wang, Binyi Su, Jianzhi Yang, Fuzhi Cao and Xiaolin Ning

Biosensors 2025, 15(10), 680; https://doi.org/10.3390/bios15100680 - 9 Oct 2025

Abstract

The high spatiotemporal resolution of optically pumped magnetometers (OPMs) makes them an essential tool for functional brain imaging, enabling accurate recordings of neuronal activity. However, physiological signals such as eye blinks and cardiac activity overlap with neural magnetic signals in the frequency domain, [...] Read more.

The high spatiotemporal resolution of optically pumped magnetometers (OPMs) makes them an essential tool for functional brain imaging, enabling accurate recordings of neuronal activity. However, physiological signals such as eye blinks and cardiac activity overlap with neural magnetic signals in the frequency domain, resulting in contamination and creating challenges for the observation of brain activity and the study of neurological disorders. To address this problem, an automatic physiological artifact removal method based on OPM magnetic reference signals and a channel attention mechanism is proposed. The randomized dependence coefficient (RDC) is employed to evaluate the correlation between independent components and reference signals, enabling reliable recognition of artifact components and the construction of training and testing datasets. A channel attention mechanism is subsequently introduced, which fuses features from global average pooling (GAP) and global max pooling (GMP) layers through convolution to establish a data-driven automatic recognition model. The backbone network is further optimized to enhance performance. Experimental results demonstrate a strong correlation between the magnetic reference signals and artifact components, confirming the reliability of magnetic signals as artifact references for OPM-MEG. The proposed model achieves an artifact recognition accuracy of 98.52% and a macro-average score of 98.15%. After artifact removal, both the event-related field (ERF) responses and the signal-to-noise ratio (SNR) are significantly improved. Leveraging the flexible and modular characteristics of OPM-MEG, this study introduces an artifact recognition framework that integrates magnetic reference signals with an attention mechanism. This approach enables highly accurate automatic recognition and removal of OPM-MEG artifacts, paving the way for real-time, automated data analysis in both scientific research and clinical applications. Full article

(This article belongs to the Section Wearable Biosensors)

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15 pages, 2459 KB

Open AccessArticle

Conductometric Chemosensor for Saccharides Based on Thin Films of Poly(3-Thienylboronic) Acid: Measurements of Transversal Resistance

by Berfinsu Kaya, Yulia Efremenko and Vladimir M. Mirsky

Biosensors 2025, 15(10), 679; https://doi.org/10.3390/bios15100679 - 9 Oct 2025

Abstract

Poly(3-thienylboronic acid) (PThBA) has recently been suggested as a conducting polymer with affinity for saccharides. In this study, thin films of this compound were deposited onto gold electrodes. The system obtained was studied as a possible chemical sensor. The measurements were performed by [...] Read more.

Poly(3-thienylboronic acid) (PThBA) has recently been suggested as a conducting polymer with affinity for saccharides. In this study, thin films of this compound were deposited onto gold electrodes. The system obtained was studied as a possible chemical sensor. The measurements were performed by impedance spectroscopy using potassium ferro/ferricyanide as a redox mediator. The thickness of the polymer and the deposition of the adhesive sublayer were optimized to achieve a compromise between the blocking of defects in the polymer layer and the unnecessary increase in the internal resistance of this conductometric sensor. A comparative study of the influence of fructose, glucose, and sorbitol on transversal polymer resistance was conducted. The binding constants for these saccharides were extracted from the concentration dependencies of sensor conductance. Among them, sorbitol showed the highest affinity with a binding constant up to ~15,000 L·mol⁻¹, followed by fructose (~8700 L·mol⁻¹) and glucose (~4500 L·mol⁻¹). In order to exclude the contribution of the analyte tautomers on the obtained binding constants, measurements of ethylene glycol were also performed. The effects of pH and the redox state of PThBA on its affinity properties were studied, revealing higher affinities at alkaline pH and in oxidized state of the chemosensitive polymer. The developed system has the capacity to be applied in chemical sensors and virtual sensor arrays with electrical affinity control. Full article

(This article belongs to the Special Issue Electrochemical Biosensor Applications in Agriculture, Environment and Health Systems)

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30 pages, 2315 KB

Open AccessReview

Progress in NiO Based Materials for Electrochemical Sensing Applications

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

Biosensors 2025, 15(10), 678; https://doi.org/10.3390/bios15100678 - 9 Oct 2025

Abstract

Nickel oxide (NiO), a wide bandgap p-type semiconductor, has emerged as a promising material for electrochemical sensing owing to its excellent redox properties, chemical stability, and facile synthesis. Its strong electrocatalytic activity enables effective detection of diverse analytes, including glucose, hydrogen peroxide, environmental [...] Read more.

Nickel oxide (NiO), a wide bandgap p-type semiconductor, has emerged as a promising material for electrochemical sensing owing to its excellent redox properties, chemical stability, and facile synthesis. Its strong electrocatalytic activity enables effective detection of diverse analytes, including glucose, hydrogen peroxide, environmental pollutants, and biomolecules. Advances in nanotechnology have enabled the development of NiO-based nanostructures such as nanoparticles, nanowires, and nanoflakes, which offer enhanced surface area and improved electron transfer. Integration with conductive materials like graphene, carbon nanotubes, and metal–organic frameworks (MOFs) further enhance sensor performance through synergistic effects. Innovations in synthesis techniques, including hydrothermal, sol–gel, and green approaches, have expanded the applicability of NiO in next-generation sensing platforms. This review summarizes recent progress in the structural engineering, composite formation, and electrochemical mechanisms of NiO-based materials for advanced electrochemical sensing applications. Full article

(This article belongs to the Special Issue Advances, Challenges and Opportunities in the Use of 2D Materials for Biosensing and Biomedical Applications)

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34 pages, 4923 KB

Open AccessReview

Recent Developments and Applications of Terahertz Spectroscopy in Food Analysis

by Pengpeng Yu, Chaoping Shen, Wenhui Zhu, Wenya Zhang, Junhui Cheng and Jinxiu Song

Biosensors 2025, 15(10), 677; https://doi.org/10.3390/bios15100677 - 8 Oct 2025

Abstract

The terahertz waves are electromagnetic waves with frequencies ranging from 0.1 to 10 THz, exhibiting characteristics of both microwave and infrared, including fingerprint characteristics, coherence, and safety. Due to the weak interactions among most organic macromolecules in substances, the vibrational modes of molecular [...] Read more.

The terahertz waves are electromagnetic waves with frequencies ranging from 0.1 to 10 THz, exhibiting characteristics of both microwave and infrared, including fingerprint characteristics, coherence, and safety. Due to the weak interactions among most organic macromolecules in substances, the vibrational modes of molecular frameworks, as well as dipole rotation and vibration transitions, often correspond to the terahertz spectral region. Consequently, there has been growing interest in applying terahertz technology within the food industry. This review summarizes the fundamental principles of terahertz spectroscopy for substance detection and highlights recent advances and applications in food analysis. Key applications include harmful contaminant detection, component analysis, quality assessment, and adulteration identification. Additionally, this review discusses current challenges in applying terahertz spectroscopy to food analysis, such as strong water absorption, matrix interference, and the lack of comprehensive spectral databases. Finally, the paper outlines future prospects, including the development of lightweight and cost-effective terahertz sources and detectors for on-site analysis, as well as the integration of terahertz spectroscopy with other modern detection technologies to enhance analytical performance. This work aims to serve as a reference for further research and development of terahertz spectroscopy in the food sector. Full article

(This article belongs to the Special Issue Optical and Electrochemical Biosensors for Biological, Environmental, and Food Analysis)

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33 pages, 781 KB

Open AccessReview

Recent Advances in Electrochemical Sensors for the Detection of Anti-Inflammatory and Antibiotic Drugs: A Comprehensive Review

by Gisele Afonso Bento Mello, Stephen Rathinaraj Benjamin, Fábio de Lima and Rosa F. Dutra

Biosensors 2025, 15(10), 676; https://doi.org/10.3390/bios15100676 - 8 Oct 2025

Abstract

Electrochemical sensors have emerged as powerful analytical tools for the detection of anti-inflammatory and antibiotic drugs due to their high sensitivity, rapid response, and cost-effectiveness compared to conventional chromatographic and spectrophotometric methods. This review highlights recent advances in electrode materials, surface modification strategies, [...] Read more.

Electrochemical sensors have emerged as powerful analytical tools for the detection of anti-inflammatory and antibiotic drugs due to their high sensitivity, rapid response, and cost-effectiveness compared to conventional chromatographic and spectrophotometric methods. This review highlights recent advances in electrode materials, surface modification strategies, and signal amplification approaches for quantifying nonsteroidal anti-inflammatory drugs (NSAIDs) and various antibiotic classes, including sulfonamides, tetracyclines, macrolides, and quinolones. Particular attention is given to nanostructured carbon-based materials, metal nanoparticles, and polymer composites that enhance electron transfer, improve selectivity, and lower limits of detection (LODs). The analytical performance of different electrochemical techniques such as cyclic voltammetry, differential pulse voltammetry, and square-wave voltammetry is critically compared across various drug targets. Trends indicate that hybrid nanomaterial-modified electrodes consistently achieve sub-micromolar detection limits in biological and environmental samples, offering potential for point-of-care diagnostics and environmental monitoring. Current challenges include improving sensor stability, mitigating fouling effects, and ensuring reproducibility in complex matrices. Future research should focus on integrated, miniaturized sensing platforms capable of multiplex detection, paving the way for rapid, portable, and sustainable analytical solutions in pharmaceutical and biomedical applications. Full article

(This article belongs to the Special Issue Functional Nanomaterials for Advanced Biosensing: From Molecular Design to Real-World Applications)

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21 pages, 2923 KB

Open AccessReview

Structure-Based Understanding of Cu²⁺ Coordination in Fluorescent Proteins for Metal Biosensor Applications—A Review

by Ki Hyun Nam

Biosensors 2025, 15(10), 675; https://doi.org/10.3390/bios15100675 - 7 Oct 2025

Abstract

Copper ions play essential roles in biological systems, but they can cause toxicity following dysregulation or excessive accumulation. In addition, environmental overexposure to Cu²⁺ can lead to serious agricultural and ecological issues. Accurate detection of Cu²⁺ is therefore critical in both [...] Read more.

Copper ions play essential roles in biological systems, but they can cause toxicity following dysregulation or excessive accumulation. In addition, environmental overexposure to Cu²⁺ can lead to serious agricultural and ecological issues. Accurate detection of Cu²⁺ is therefore critical in both medical diagnostics and environmental monitoring. Fluorescent proteins (FPs), which are widely used in molecular and cell biology, have been suggested as attractive modalities for metal ion detection owing to their biocompatibility and specific responsiveness to metal ions. The fluorescence emission of FPs is efficiently quenched by Cu²⁺ in a reversible manner, suggesting the potential to develop Cu²⁺-responsive biosensors. To develop highly sensitive and selective Cu²⁺ biosensors based on FPs, an understanding of Cu²⁺ binding to FPs is crucial, along with FP engineering guided by structural analysis. In this study, the molecular properties of FPs and their fluorescence responses to metal ions were reviewed. The crystal structures of FPs complexed with Cu²⁺ were analyzed, revealing both specific and nonspecific Cu²⁺ binding modes. This structural analysis provides insights into the potential of engineering FPs to enhance sensitivity and selectivity for Cu²⁺ detection. Full article

(This article belongs to the Special Issue Fluorescent Probes: Design and Biological Applications)

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17 pages, 2361 KB

Open AccessArticle

A Biofuel Cell for Electricity Generation from Biomass-Derived Cellobiose

by Piyanut Pinyou, Peeranat Jatooratthawichot, Luciranon Sribrahma, Salila Pengthaisong, Chamaipon Beagbandee, Kantapat Chansaenpak, Vincent Blay and James R. Ketudat Cairns

Biosensors 2025, 15(10), 674; https://doi.org/10.3390/bios15100674 - 7 Oct 2025

Abstract

We have developed a new bioanode based on a cascade of reactions catalyzed by two enzymes. A glassy carbon electrode is modified with β-glucosidase and glucose oxidase enzymes entrapped within an osmium redox polymer. Cellobiose, the fuel for the anode, is hydrolyzed by [...] Read more.

We have developed a new bioanode based on a cascade of reactions catalyzed by two enzymes. A glassy carbon electrode is modified with β-glucosidase and glucose oxidase enzymes entrapped within an osmium redox polymer. Cellobiose, the fuel for the anode, is hydrolyzed by β-glucosidase (TxGH116), yielding two molecules of D-glucose. Glucose is then oxidized by glucose oxidase (GOx) into δ-gluconolactone and produces electrons that are transferred to the electrode mediated by osmium redox polymer. We investigated the kinetic parameters of both enzymes at different temperatures. For GOx, the effect of enzyme loading and enzyme/polymer ratio were also optimized. The proposed bioanode is coupled to a biocathode based on horseradish peroxidase (HRP) in which H₂O₂, the oxidant, is reduced. We investigated the performance of the biofuel cell on cellobiose and sugarcane hydrolysates subjected to different pretreatments. Alkaline pretreatments of biomass were found to be more effective than phosphoric acid pretreatment. Adding TxGH116 β-glucosidase further enhanced current generation, even when commercial cellulase was used. Full article

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

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41 pages, 25159 KB

Open AccessReview

Overview on the Sensing Materials and Methods Based on Reversible Addition–Fragmentation Chain-Transfer Polymerization

by Zhao-Jiang Yu, Lin Liu, Su-Ling Yang and Shuai-Bing Yu

Biosensors 2025, 15(10), 673; https://doi.org/10.3390/bios15100673 - 7 Oct 2025

Abstract

Reversible addition–fragmentation chain-transfer (RAFT) polymerization has become an efficient method in the field of polymer synthesis. Recently, the RAFT polymerization technique has been successfully used to prepare functional materials and develop various sensing methods used in different scenarios. The polymerization reaction can be [...] Read more.

Reversible addition–fragmentation chain-transfer (RAFT) polymerization has become an efficient method in the field of polymer synthesis. Recently, the RAFT polymerization technique has been successfully used to prepare functional materials and develop various sensing methods used in different scenarios. The polymerization reaction can be initiated by thermal, electrochemical, photochemical, enzymatic, and mechanical stimulation. More interestingly, RAFT polymerization can be performed in situ by recruiting a large number of signal tags at the solid interface to amplify the signals. In this review, we addressed the latest achievements in the preparation of sensing materials and the design of different sensors based on the RAFT polymerization technique for sensing ions and small molecules and bioimaging of tumor cells and viruses. Then, electrochemical and optical biosensors through the signal amplification of the RAFT polymerization method were summarized. This work could provide inspiration for researchers to prepare fascinating sensing materials and develop novel detection technologies applied in various fields. Full article

(This article belongs to the Special Issue Signal Amplification in Biosensing)

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27 pages, 1664 KB

Open AccessReview

Actomyosin-Based Nanodevices for Sensing and Actuation: Bridging Biology and Bioengineering

by Nicolas M. Brunet, Peng Xiong and Prescott Bryant Chase

Biosensors 2025, 15(10), 672; https://doi.org/10.3390/bios15100672 - 4 Oct 2025

Abstract

The actomyosin complex—nature’s dynamic engine composed of actin filaments and myosin motors—is emerging as a versatile tool for bio-integrated nanotechnology. This review explores the growing potential of actomyosin-powered systems in biosensing and actuation applications, highlighting their compatibility with physiological conditions, responsiveness to biochemical [...] Read more.

The actomyosin complex—nature’s dynamic engine composed of actin filaments and myosin motors—is emerging as a versatile tool for bio-integrated nanotechnology. This review explores the growing potential of actomyosin-powered systems in biosensing and actuation applications, highlighting their compatibility with physiological conditions, responsiveness to biochemical and physical cues and modular adaptability. We begin with a comparative overview of natural and synthetic nanomachines, positioning actomyosin as a uniquely scalable and biocompatible platform. We then discuss experimental advances in controlling actomyosin activity through ATP, calcium, heat, light and electric fields, as well as their integration into in vitro motility assays, soft robotics and neural interface systems. Emphasis is placed on longstanding efforts to harness actomyosin as a biosensing element—capable of converting chemical or environmental signals into measurable mechanical or electrical outputs that can be used to provide valuable clinical and basic science information such as functional consequences of disease-associated genetic variants in cardiovascular genes. We also highlight engineering challenges such as stability, spatial control and upscaling, and examine speculative future directions, including emotion-responsive nanodevices. By bridging cell biology and bioengineering, actomyosin-based systems offer promising avenues for real-time sensing, diagnostics and therapeutic feedback in next-generation biosensors. Full article

(This article belongs to the Special Issue Biosensors for Personalized Treatment)

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25 pages, 2285 KB

Open AccessArticle

Rationally Designed Molecularly Imprinted Polymer Electrochemical Biosensor with Graphene Oxide Interface for Selective Detection of Matrix Metalloproteinase-8 (MMP-8)

by Jae Won Lee, Rowoon Park, Sangheon Jeon, Sung Hyun Kim, Young Woo Kwon, Dong-Wook Han and Suck Won Hong

Biosensors 2025, 15(10), 671; https://doi.org/10.3390/bios15100671 - 4 Oct 2025

Abstract

Molecularly imprinted polymer (MIP) biosensors offer an attractive strategy for selective biomolecule detection, yet imprinting proteins with structural fidelity remains a major challenge. In this work, we present a rationally designed electrochemical biosensor for matrix metal-loproteinase-8 (MMP-8), a key salivary biomarker of periodontal [...] Read more.

Molecularly imprinted polymer (MIP) biosensors offer an attractive strategy for selective biomolecule detection, yet imprinting proteins with structural fidelity remains a major challenge. In this work, we present a rationally designed electrochemical biosensor for matrix metal-loproteinase-8 (MMP-8), a key salivary biomarker of periodontal disease. By integrating graphene oxide (GO) with electropolymerized poly(eriochrome black T, EBT) films on screen-printed carbon electrodes, the partially reduced GO interface enhanced electrical conductivity and facilitated the formation of well-defined poly(EBT) films with re-designed polymerization route, while template extraction generated artificial antibody-like sites capable of specific protein binding. The MIP-based electrodes were comprehensively validated through morphological, spectroscopic, and electrochemical analyses, demonstrating stable and selective recognition of MMP-8 against structurally similar interferents. Complementary density functional theory (DFT) modeling revealed energetically favorable interactions between the EBT monomer and catalytic residues of MMP-8, providing molecular-level insights into imprinting specificity. These experimental and computational findings highlight the importance of rational monomer selection and nanomaterial-assisted polymerization in achieving selective protein imprinting. This work presents a systematic approach that integrates electrochemical engineering, nanomaterial interfaces, and computational validation to address long-standing challenges in protein-based MIP biosensors. By bridging molecular design with practical sensing performance, this study advances the translational potential of MIP-based electrochemical biosensors for point-of-care applications. Full article

(This article belongs to the Special Issue Molecularly Imprinted Polymers-Based Biosensors)

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17 pages, 4089 KB

Open AccessArticle

Affinity-Based Copolymer Coating for Oriented Protein Immobilization in Biosensor Development

by Lorenzo Zarini, Thomas Carzaniga, Morena Pirotta, Francesco Damin, Dario Brambilla, Marcella Chiari, Ivan Bassanini, Paola Gagni, Alessandro Mussida, Luca Casiraghi, Marco Buscaglia and Laura Sola

Biosensors 2025, 15(10), 670; https://doi.org/10.3390/bios15100670 - 4 Oct 2025

Abstract

Effective protein immobilization is a critical step in biosensor development, as it ensures the stability, functionality, and orientation of biomolecules on the sensor surface. Here, we present a novel affinity-based terpolymer coating designed to enhance protein immobilization for biosensor applications. The novelty lies [...] Read more.

Effective protein immobilization is a critical step in biosensor development, as it ensures the stability, functionality, and orientation of biomolecules on the sensor surface. Here, we present a novel affinity-based terpolymer coating designed to enhance protein immobilization for biosensor applications. The novelty lies in the incorporation of nitrilotriacetic acid (NTA) ligands directly into the polymeric chains, facilitating histidine-tagged protein oriented binding through a robust metal-chelating interaction. To validate the system, magnetic microbeads coated with the polymer were tested for their ability to bind native and His-tagged proteins. The results demonstrated the superior binding capacity, enhanced stability, and reversibility of the interactions compared to traditional coatings, which immobilize proteins through nucleophile reactions with amine residues. Moreover, enzyme immobilization tests confirmed that the polymer preserves enzymatic activity, highlighting its potential for biosensor applications requiring functional biomolecules. This innovative polymeric coating offers a fast, versatile, and scalable solution for next-generation biosensor platforms, paving the way for improved sensitivity, reliability, and accessibility in diagnostic and analytical technologies. Full article

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

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14 pages, 5634 KB

Open AccessArticle

Validation of Analytical Models for the Development of Non-Invasive Glucose Measurement Devices

by Bruna Gabriela Pedro, Fernanda Maltauro de Cordova, Yana Picinin Sandri Lissarassa, Fabricio Noveletto and Pedro Bertemes-Filho

Biosensors 2025, 15(10), 669; https://doi.org/10.3390/bios15100669 - 3 Oct 2025

Abstract

Non-invasive glucose monitoring remains a persistent challenge in the scientific literature due to the complexity of biological samples and the limitations of traditional optical methods. Although advances have been made in the use of near-infrared (NIR) spectrophotometry, the direct application of the Lambert–Beer [...] Read more.

Non-invasive glucose monitoring remains a persistent challenge in the scientific literature due to the complexity of biological samples and the limitations of traditional optical methods. Although advances have been made in the use of near-infrared (NIR) spectrophotometry, the direct application of the Lambert–Beer Law (LBL) to such systems has proven problematic, particularly due to the non-linear behavior observed in complex organic solutions. In this context, the objective of this work is to propose and validate a methodology for the determination of the extinction coefficient of glucose in blood, taking into account the limitations of the LBL and the specificities of molecular interactions. The method was optimized through an iterative process to provide consistent results over multiple replicates. Whole blood and plasma samples from two individuals were analyzed using spectrophotometry in the 700 nm to 1400 nm. The results showed that glucose has a high spectral sensitivity close to 975 nm.The extinction coefficients obtained for glucose (

α_{g}

) ranged from −0.0045 to −0.0053, and for insulin (

α_{i}

) from 0.000075 to 0.000078, with small inter-individual variations, indicating strong stability of these parameters. The non-linear behaviour observed in the relationship between absorbance, glucose and insulin concentrations might be explained by the changes imposed by both s and p orbitals of organic molecules. In order to make the LBL valid in this context, the extinction coefficients must be functions of the analyte concentrations, and the insulin concentration must also be a function of glucose. A regression model was found which allows to differentiate glucose from insulin concentration, by considering the cuvette thickness and sample absorbance at 965, 975, and 985 nm. It can also be concluded from experiments that wavelength of approximately 975 nm is more suitable for blood glucose calculation by using photometry. The final spectra are consistent with those reported in mid-infrared validation studies, suggesting that the proposed model encompasses the key aspects of glucose behavior in biological media. Full article

(This article belongs to the Special Issue Recent Advances in Glucose Biosensors)

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29 pages, 2876 KB

Open AccessReview

Exhaled Aldehydes and Ketones as Biomarkers of Lung Cancer and Diabetes: Review of Sensor Technologies for Early Disease Diagnosis

by Rafał Kiejzik, Tomasz Wasilewski and Wojciech Kamysz

Biosensors 2025, 15(10), 668; https://doi.org/10.3390/bios15100668 - 3 Oct 2025

Abstract

Exhaled breath (EB) contains numerous volatile organic compounds (VOCs) that can reflect pathological metabolic processes, making breath analysis a promising non-invasive diagnostic approach. In particular, volatile aldehydes and ketones have been identified as disease biomarkers in EB. Gas sensors are expected to play [...] Read more.

Exhaled breath (EB) contains numerous volatile organic compounds (VOCs) that can reflect pathological metabolic processes, making breath analysis a promising non-invasive diagnostic approach. In particular, volatile aldehydes and ketones have been identified as disease biomarkers in EB. Gas sensors are expected to play a crucial role in the diagnosis of numerous diseases at an early stage. Among the various available approaches, sensors stand out as especially attractive tools for diagnosing diseases such as lung cancer (LC) and diabetes, due to their affordability and operational simplicity. There is an urgent need in the field of disease detection for the development of affordable, non-invasive, and user-friendly sensors capable of detecting various biomarkers. Devices of the new generation should also demonstrate high repeatability of measurements and extended operational stability of the employed sensors. Due to these demands, the past few years have seen significant advancements in the development and implementation of electronic noses (ENs), which are composed of an array of sensors for the determination of VOCs present in EB. To meet these requirements, the development and integration of advanced receptor coatings on sensor transducers is essential. These coatings include nanostructured materials, molecularly imprinted polymers, and bioreceptors, which collectively enhance selectivity, sensitivity, and operational stability. However, reliable biomarker detection in point-of-care (PoC) mode remains a significant challenge, constrained by several factors. This review provides a comprehensive and critical evaluation of recent studies demonstrating that the detection of VOCs using gas sensor platforms enables disease detection and can be implemented in PoC mode. Full article

(This article belongs to the Special Issue Functional Materials for Biosensing Applications)

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