Biosensors

13 pages, 1808 KiB

Open AccessArticle

Prediction of Thrombus Formation within an Oxygenator via Bioimpedance Analysis

by Jan Korte, Tobias Lauwigi, Lisa Herzog, Alexander Theißen, Kai Suchorski, Lasse J. Strudthoff, Jannis Focke, Sebastian V. Jansen, Thomas Gries, Rolf Rossaint, Christian Bleilevens and Patrick Winnersbach

Biosensors 2024, 14(10), 511; https://doi.org/10.3390/bios14100511 - 18 Oct 2024

Viewed by 249

Abstract

Blood clot formation inside the membrane oxygenator (MO) remains a risk in extracorporeal membrane oxygenation (ECMO). It is associated with thromboembolic complications and normally detectable only at an advanced stage. Established clinical monitoring techniques lack predictive capabilities, emphasizing the need for refinement in [...] Read more.

Blood clot formation inside the membrane oxygenator (MO) remains a risk in extracorporeal membrane oxygenation (ECMO). It is associated with thromboembolic complications and normally detectable only at an advanced stage. Established clinical monitoring techniques lack predictive capabilities, emphasizing the need for refinement in MO monitoring towards an early warning system. In this study, an MO was modified by integrating four sensor fibers in the middle of the hollow fiber mat bundle, allowing for bioimpedance measurement within the MO. The modified MO was perfused with human blood in an in vitro test circuit until fulminant clot formation. The optical analysis of clot residues on the extracted hollow fibers showed a clot deposition area of 51.88% ± 14.25%. This was detectable via an increased bioimpedance signal with a significant increase 5 min in advance to fulminant clot formation inside the MO, which was monitored by the clinical gold standard (pressure difference across the MO (dp-MO)). This study demonstrates the feasibility of detecting clot growth early and effectively by measuring bioimpedance within an MO using integrated sensor fibers. Thus, bioimpedance may even outperform the clinical gold standard of dp-MO as a monitoring method by providing earlier clot detection. Full article

(This article belongs to the Special Issue Biophysical Sensors for Biomedical/Health Monitoring Applications (2nd Edition))

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15 pages, 7613 KiB

Open AccessArticle

Electrochemical Analysis of Amyloid Plaques and ApoE4 with Chitosan-Coated Gold Nanostars for Alzheimer’s Detection

by Min-Kyung Shin, Ariadna Schuck, Minhee Kang and Yong-Sang Kim

Biosensors 2024, 14(10), 510; https://doi.org/10.3390/bios14100510 - 17 Oct 2024

Viewed by 314

Abstract

Monitoring the progression of Alzheimer’s disease (AD) is crucial for mitigating dementia symptoms, alleviating pain, and improving mobility. Traditionally, AD biomarkers like amyloid plaques are predominantly identified in cerebrospinal fluid (CSF) due to their concentrated presence. However, detecting these markers in blood is [...] Read more.

Monitoring the progression of Alzheimer’s disease (AD) is crucial for mitigating dementia symptoms, alleviating pain, and improving mobility. Traditionally, AD biomarkers like amyloid plaques are predominantly identified in cerebrospinal fluid (CSF) due to their concentrated presence. However, detecting these markers in blood is hindered by the blood–brain barrier (BBB), resulting in lower concentrations. To address this challenge and identify pertinent AD biomarkers—specifically amyloid plaques and apolipoprotein E4 (ApoE4)—in blood plasma, we propose an innovative approach. This involves enhancing a screen-printed carbon electrode (SPCE) with an immobilization matrix comprising gold nanostars (AuNSs) coated with chitosan. Morphological and electrical analyses confirmed superior dispersion and conductivity with 0.5% chitosan, supported by UV–Vis spectroscopy, cyclic voltammetry, and Nyquist plots. Subsequent clinical assays measured electrical responses to quantify amyloid-β 42 (Aβ42) (15.63–1000 pg/mL) and APoE4 levels (0.41 to 40 ng/mL) in human blood plasma samples. Differential pulse voltammetry (DPV) responses exhibited peak currents proportional to biomarker concentrations, demonstrating high linear correlations (0.985 for Aβ42 and 0.919 for APoE4) with minimal error bars. Cross-reactivity tests with mixed solutions of amyloid-β 40 (Aβ40), Aβ42, and ApoE4 indicated minimal interference between biomarkers (<3% variation), further confirming the high specificity of the developed sensor. Validation studies demonstrated a strong concurrence with the gold-standard enzyme-linked immunosorbent assay (ELISA), while interference tests indicated a minimal variation in peak currents. This improved device presents promising potential as a point-of-care system, offering a less invasive, cost-effective, and simplified approach to detecting and tracking the progression of AD. The substantial surface binding area further supports the efficacy of our method, offering a promising avenue for advancing AD diagnostics. Full article

(This article belongs to the Special Issue Nano Biosensors and Their Applications for In Vivo/Vitro Diagnosis—2nd Edition)

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13 pages, 2541 KiB

Open AccessArticle

Enhancing Target Detection: A Fluorescence-Based Streptavidin-Bead Displacement Assay

by Sireethorn Tungsirisurp and Nunzianda Frascione

Biosensors 2024, 14(10), 509; https://doi.org/10.3390/bios14100509 - 17 Oct 2024

Viewed by 324

Abstract

Fluorescence-based aptasensors have been regarded as innovative analytical tools for the detection and quantification of analytes in many fields, including medicine and therapeutics. Using DNA aptamers as the biosensor recognition component, conventional molecular beacon aptasensor designs utilise target-induced structural switches of the DNA [...] Read more.

Fluorescence-based aptasensors have been regarded as innovative analytical tools for the detection and quantification of analytes in many fields, including medicine and therapeutics. Using DNA aptamers as the biosensor recognition component, conventional molecular beacon aptasensor designs utilise target-induced structural switches of the DNA aptamers to generate a measurable fluorescent signal. However, not all DNA aptamers undergo sufficient target-specific conformational changes for significant fluorescence measurements. Here, the use of complementary ‘antisense’ strands is proposed to enable fluorescence measurement through strand displacement upon target binding. Using a published target-specific DNA aptamer against the receptor binding domain of SARS-CoV-2, we designed a streptavidin-aptamer bead complex as a fluorescence displacement assay for target detection. The developed assay demonstrates a linear range from 50 to 800 nanomolar (nM) with a limit of detection calculated at 67.5 nM and a limit of quantification calculated at 204.5 nM. This provides a ‘fit-for-purpose’ model assay for the detection and quantification of any target of interest by adapting and functionalising a suitable target-specific DNA aptamer and its complementary antisense strand. Full article

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

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14 pages, 3205 KiB

Open AccessArticle

High-Performance Flexible PLA/BTO-Based Pressure Sensor for Motion Monitoring and Human–Computer Interaction

by Xuguang Sui, Qingmiao Mu, Jia Li, Bo Zhao, Hongxi Gu, Han Yu, Juan Du, Lijun Ren and Dengwei Hu

Biosensors 2024, 14(10), 508; https://doi.org/10.3390/bios14100508 - 17 Oct 2024

Viewed by 413

Abstract

Flexible electronics show wide application prospects in electronic skin, health monitoring, and human–machine interfacing. As an essential part of flexible electronics, flexible pressure sensors have become a compelling subject of academic research. There is an urgent need to develop piezoelectric sensors with high [...] Read more.

Flexible electronics show wide application prospects in electronic skin, health monitoring, and human–machine interfacing. As an essential part of flexible electronics, flexible pressure sensors have become a compelling subject of academic research. There is an urgent need to develop piezoelectric sensors with high sensitivity and stability. In this work, the high flexibility of polylactic acid (PLA) film and the excellent ferroelectric properties and high dielectric constant of tetragonal barium titanate (BTO) led to their use as filling materials to fabricate flexible piezoelectric composite films by spinning coating. PLA is used to produce flexible binding substrates, and BTO is added to the composite to enhance its electrical output by improving its piezoelectric performance. The peak output voltage of the PLA/BTO tetragonal piezoelectric film is 22.57 V, and the maximum short-circuit current was 3041 nA. Durability tests showed that during 40,000 s of continuous operation, in the range of 15~120 kPa, the linear relationship between pressure and the film was excellent, the sensitivity for the output voltage is 0.176 V/kPa, and the output current is 27.77 nA/kPa. The piezoelectric pressure sensor (PPS) also enables accurate motion detection, and the extensive capabilities of the PENG highlight its potential in advancing motion sensing and human–computer interactions. Full article

(This article belongs to the Special Issue Recent Advances in Hydrogels-Based Biosensors for Point-of-Care Testing)

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3 pages, 135 KiB

Open AccessEditorial

Innovations in Microfluidics to Enable Novel Biomedical Applications

by Nan Xiang and Zhonghua Ni

Biosensors 2024, 14(10), 507; https://doi.org/10.3390/bios14100507 - 17 Oct 2024

Viewed by 258

Abstract

As a new technique for precisely controlling micro-/nanoparticles and fluids at the microscale, microfluidics has been attracting increased interest in the fields of material science, medical diagnosis, biological research, and even soft robotics [...] Full article

(This article belongs to the Special Issue Microfluidics for Biomedical Applications (Volume II))

17 pages, 10881 KiB

Open AccessReview

Role of Peroxynitrite in the Pathogenesis of Parkinson’s Disease and Its Fluorescence Imaging-Based Detection

by Jiye Lv, Feiyu Chen, Changchan Zhang, Yubing Kang, Yan Yang and Chengwu Zhang

Biosensors 2024, 14(10), 506; https://doi.org/10.3390/bios14100506 - 17 Oct 2024

Viewed by 310

Abstract

Parkinson’s disease (PD) is the second most common neurodegenerative disorder, affecting the lives of millions of people worldwide. Although the mechanism underlying PD pathogenesis is largely undefined, increasing evidence indicates that oxidative and nitrosative stresses play a crucial role in PD occurrence and [...] Read more.

Parkinson’s disease (PD) is the second most common neurodegenerative disorder, affecting the lives of millions of people worldwide. Although the mechanism underlying PD pathogenesis is largely undefined, increasing evidence indicates that oxidative and nitrosative stresses play a crucial role in PD occurrence and development. Among them, the role of oxidative stress has been widely acknowledged, but there is relatively less attention given to nitrosative stress, which is mainly derived from peroxynitrite. In the present review, after briefly introducing the background of PD, we discuss the physiopathological function of peroxynitrite and especially highlight how overloaded peroxynitrite is involved in PD pathogenesis. Then, we summarize the currently reported fluorescence imaging-based peroxynitrite detection probes. Moreover, we specifically emphasize the probes that have been applied in PD research. Finally, we propose perspectives on how to develop a more applicable peroxynitrite probe and leverage it for PD theranostics. Conclusively, the present review broadens the knowledge on the pathological role of peroxynitrite in the context of PD and sheds light on how to develop and utilize fluorescence imaging-based strategies for peroxynitrite detection. Full article

(This article belongs to the Special Issue Fluorescent Biosensors: New Methods, Devices and Important Applications)

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16 pages, 2525 KiB

Open AccessArticle

SDBS-AEO Mixture for Triton X-100 Replacement: Surface Activity and Application in Biosensors

by Zhenzhen Li, Lei Wang, Mengjie Tang, Yulong Sun, Li Zhang and Zhongxiu Chen

Biosensors 2024, 14(10), 505; https://doi.org/10.3390/bios14100505 - 16 Oct 2024

Viewed by 338

Abstract

Triton X-100 (TX-100) is a commonly used surfactant in the manufacture of biosensors. The factors limiting the use of TX-100 in biosensors are environmental concerns. In this study, the binary system of sodium dodecyl benzene sulfonate (SDBS) and fatty alcohol-polyoxyethlene ether (AEO) was [...] Read more.

Triton X-100 (TX-100) is a commonly used surfactant in the manufacture of biosensors. The factors limiting the use of TX-100 in biosensors are environmental concerns. In this study, the binary system of sodium dodecyl benzene sulfonate (SDBS) and fatty alcohol-polyoxyethlene ether (AEO) was investigated from the physicochemical principle of surfactant interaction and its application in biosensors. The results demonstrated that a mixture of SDBS and AEO at an appropriate molar ratio had a comparable activity to TX-100 in terms of surface activity, micelle formation, dynamic adsorption, foaming, emulsifying, and cell permeability. Theory and experimentation support the idea that SDBS-AEO might take the place of TX-100 in the manufacturing of biosensors. This study contributes to the development of alternatives to TX-100 and provides a new perspective for an in-depth study of the interaction mechanism of additives in biosensor design. Full article

(This article belongs to the Special Issue State-of-the-Art Biosensors in China (2nd Edition))

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18 pages, 4283 KiB

Open AccessArticle

A Machine Learning Assisted Non-Enzymatic Electrochemical Biosensor to Detect Urea Based on Multi-Walled Carbon Nanotube Functionalized with Copper Oxide Micro-Flowers

by Jitendra B. Zalke, Manish L. Bhaiyya, Pooja A. Jain, Devashree N. Sakharkar, Jayu Kalambe, Nitin P. Narkhede, Mangesh B. Thakre, Dinesh R. Rotake, Madhusudan B. Kulkarni and Shiv Govind Singh

Biosensors 2024, 14(10), 504; https://doi.org/10.3390/bios14100504 (registering DOI) - 15 Oct 2024

Viewed by 409

Abstract

Detecting urea is crucial for diagnosing related health conditions and ensuring timely medical intervention. The addition of machine learning (ML) technologies has completely changed the field of biochemical sensing, providing enhanced accuracy and reliability. In the present work, an ML-assisted screen-printed, flexible, electrochemical, [...] Read more.

Detecting urea is crucial for diagnosing related health conditions and ensuring timely medical intervention. The addition of machine learning (ML) technologies has completely changed the field of biochemical sensing, providing enhanced accuracy and reliability. In the present work, an ML-assisted screen-printed, flexible, electrochemical, non-enzymatic biosensor was proposed to quantify urea concentrations. For the detection of urea, the biosensor was modified with a multi-walled carbon nanotube-zinc oxide (MWCNT-ZnO) nanocomposite functionalized with copper oxide (CuO) micro-flowers (MFs). Further, the CuO-MFs were synthesized using a standard sol-gel approach, and the obtained particles were subjected to various characterization techniques, including X-ray diffraction (XRD), field emission scanning electron microscopy (FESEM), and Fourier transform infrared (FTIR) spectroscopy. The sensor’s performance for urea detection was evaluated by assessing the dependence of peak currents on analyte concentration using cyclic voltammetry (CV) at different scan rates of 50, 75, and 100 mV/s. The designed non-enzymatic biosensor showed an acceptable linear range of operation of 0.5–8 mM, and the limit of detection (LoD) observed was 78.479 nM, which is well aligned with the urea concentration found in human blood and exhibits a good sensitivity of 117.98 mA mM⁻¹ cm⁻². Additionally, different regression-based ML models were applied to determine CV parameters to predict urea concentrations experimentally. ML significantly improves the accuracy and reliability of screen-printed biosensors, enabling accurate predictions of urea levels. Finally, the combination of ML and biosensor design emphasizes not only the high sensitivity and accuracy of the sensor but also its potential for complex non-enzymatic urea detection applications. Future advancements in accurate biochemical sensing technologies are made possible by this strong and dependable methodology. Full article

(This article belongs to the Special Issue Advances in Biosensing and Bioanalysis Based on Nanozymes)

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14 pages, 4605 KiB

Open AccessArticle

Electrical Impedance Spectroscopy as a Tool to Detect the Epithelial to Mesenchymal Transition in Prostate Cancer Cells

by Lexi L. C. Simpkins, Luis A. Henriquez, Mary Tran and Tayloria N. G. Adams

Biosensors 2024, 14(10), 503; https://doi.org/10.3390/bios14100503 (registering DOI) - 15 Oct 2024

Viewed by 312

Abstract

Prostate cancer (PCa) remains a significant health threat, with chemoresistance and recurrence posing major challenges despite advances in treatment. The epithelial to mesenchymal transition (EMT), a biochemical process where cells lose epithelial features and gain mesenchymal traits, is linked to chemoresistance and metastasis. [...] Read more.

Prostate cancer (PCa) remains a significant health threat, with chemoresistance and recurrence posing major challenges despite advances in treatment. The epithelial to mesenchymal transition (EMT), a biochemical process where cells lose epithelial features and gain mesenchymal traits, is linked to chemoresistance and metastasis. Electrical impedance spectroscopy (EIS), a novel label-free electrokinetic technique, offers promise in detecting cell phenotype changes. In this study, we employed EIS to detect EMT in prostate cancer cells (PCCs). PC3, DU145, and LNCaP cells were treated with EMT induction media for five days. EIS characterization revealed unique impedance spectra correlating with metastatic potential, distinguishing DU145 EMT+ and EMT− cells, and LNCaP EMT+ and EMT− cells (in combination with dielectrophoresis), with comparisons made to epithelial and mesenchymal controls. These changes were supported by shifts in electrical signatures, morphologies, and protein expression, including the downregulation of E-cadherin and upregulation of vimentin. No phenotype change was observed in PC3 cells, which maintained a mesenchymal phenotype. EMT+ cells were also distinguishable from mixtures of EMT+ and EMT− cells. This study demonstrates key advancements: the application of EIS and dielectrophoresis for label-free EMT detection in PCCs, characterization of cell electrical signatures after EMT, and EIS sensitivity to EMT transitions. Detecting EMT in PCa is important to the development of more effective treatments and overcoming the challenges of chemoresistance. Full article

(This article belongs to the Section Biosensors and Healthcare)

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23 pages, 16627 KiB

Open AccessArticle

Intelligent Evaluation and Dynamic Prediction of Oysters Freshness with Electronic Nose Non-Destructive Monitoring and Machine Learning

by Baichuan Wang, Yueyue Li, Kang Liu, Guangfen Wei, Aixiang He, Weifu Kong and Xiaoshuan Zhang

Biosensors 2024, 14(10), 502; https://doi.org/10.3390/bios14100502 - 14 Oct 2024

Viewed by 446

Abstract

Physiological and environmental fluctuations in the oyster cold chain can lead to quality deterioration, highlighting the importance of monitoring and evaluating oyster freshness. In this study, an electronic nose was developed using ten partially selective metal oxide-based gas sensors for rapid freshness assessment. [...] Read more.

Physiological and environmental fluctuations in the oyster cold chain can lead to quality deterioration, highlighting the importance of monitoring and evaluating oyster freshness. In this study, an electronic nose was developed using ten partially selective metal oxide-based gas sensors for rapid freshness assessment. Simultaneous analyses, including GC-MS, TVBN, microorganism, texture, and sensory evaluations, were conducted to assess the quality status of oysters. Real-time electronic nose measurements were taken at various storage temperatures (4 °C, 12 °C, 20 °C, 28 °C) to thoroughly investigate quality changes under different storage conditions. Principal component analysis was utilized to reduce the 10-dimensional vectors to 3-dimensional vectors, enabling the clustering of samples into fresh, sub-fresh, and decayed categories. A GA-BP neural network model based on these three classes achieved a test data accuracy rate exceeding 93%. Expert input was solicited for performance analysis and optimization suggestions enhanced the efficiency and applicability of the established prediction system. The results demonstrate that combining an electronic nose with quality indices is an effective approach for diagnosing oyster spoilage and mitigating quality and safety risks in the oyster industry. Full article

(This article belongs to the Special Issue Biosensing Strategies for Food Safety Applications)

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33 pages, 4616 KiB

Open AccessReview

Progression in Near-Infrared Fluorescence Imaging Technology for Lung Cancer Management

by Xinglong Chen, Yuning Li, Jialin Su, Lemeng Zhang and Hongwen Liu

Biosensors 2024, 14(10), 501; https://doi.org/10.3390/bios14100501 - 14 Oct 2024

Viewed by 431

Abstract

Lung cancer is a major threat to human health and a leading cause of death. Accurate localization of tumors in vivo is crucial for subsequent treatment. In recent years, fluorescent imaging technology has become a focal point in tumor diagnosis and treatment due [...] Read more.

Lung cancer is a major threat to human health and a leading cause of death. Accurate localization of tumors in vivo is crucial for subsequent treatment. In recent years, fluorescent imaging technology has become a focal point in tumor diagnosis and treatment due to its high sensitivity, strong selectivity, non-invasiveness, and multifunctionality. Molecular probes-based fluorescent imaging not only enables real-time in vivo imaging through fluorescence signals but also integrates therapeutic functions, drug screening, and efficacy monitoring to facilitate comprehensive diagnosis and treatment. Among them, near-infrared (NIR) fluorescence imaging is particularly prominent due to its improved in vivo imaging effect. This trend toward multifunctionality is a significant aspect of the future advancement of fluorescent imaging technology. In the past years, great progress has been made in the field of NIR fluorescence imaging for lung cancer management, as well as the emergence of new problems and challenges. This paper generally summarizes the application of NIR fluorescence imaging technology in these areas in the past five years, including the design, detection principles, and clinical applications, with the aim of advancing more efficient NIR fluorescence imaging technologies to enhance the accuracy of tumor diagnosis and treatment. Full article

(This article belongs to the Special Issue Probes for Biosensing and Bioimaging)

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24 pages, 5046 KiB

Open AccessArticle

Ultrasensitive Electrochemical Detection of Salmonella typhimurium in Food Matrices Using Surface-Modified Bacterial Cellulose with Immobilized Phage Particles

by Wajid Hussain, Huan Wang, Xiaohan Yang, Muhammad Wajid Ullah, Jawad Hussain, Najeeb Ullah, Mazhar Ul-Islam, Mohamed F. Awad and Shenqi Wang

Biosensors 2024, 14(10), 500; https://doi.org/10.3390/bios14100500 - 14 Oct 2024

Viewed by 642

Abstract

The rapid and sensitive detection of Salmonella typhimurium in food matrices is crucial for ensuring food safety. This study presents the development of an ultrasensitive electrochemical biosensor using surface-modified bacterial cellulose (BC) integrated with polypyrrole (Ppy) and reduced graphene oxide (RGO), further functionalized [...] Read more.

The rapid and sensitive detection of Salmonella typhimurium in food matrices is crucial for ensuring food safety. This study presents the development of an ultrasensitive electrochemical biosensor using surface-modified bacterial cellulose (BC) integrated with polypyrrole (Ppy) and reduced graphene oxide (RGO), further functionalized with immobilized S. typhimurium-specific phage particles. The BC substrate, with its ultra-fibrous and porous structure, was modified through in situ oxidative polymerization of Ppy and RGO, resulting in a highly conductive and flexible biointerface. The immobilization of phages onto this composite was facilitated by electrostatic interactions between the polycationic Ppy and the negatively charged phage capsid heads, optimizing phage orientation and enhancing bacterial capture efficiency. Morphological and chemical characterization confirmed the successful fabrication and phage immobilization. The biosensor demonstrated a detection limit of 1 CFU/mL for S. typhimurium in phosphate-buffered saline (PBS), with a linear detection range spanning 10⁰ to 10⁷ CFU/mL. In real samples, the sensor achieved detection limits of 5 CFU/mL in milk and 3 CFU/mL in chicken, with a linear detection range spanning 10⁰ to 10⁶ CFU/mL, maintaining high accuracy and reproducibility. The biosensor also effectively discriminated between live and dead bacterial cells, demonstrating its potential in real-world food safety applications. The biosensor performed excellently over a wide pH range (4–10) and remained stable for up to six weeks. Overall, the developed BC/Ppy/RGO–phage biosensor offers a promising tool for the rapid, sensitive, and selective detection of S. typhimurium, with robust performance across different food matrices. Full article

(This article belongs to the Special Issue Advancements in Biosensors for Foodborne Pathogens Detection)

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3 pages, 160 KiB

Open AccessEditorial

Trends and Perspectives in Biosensing and Diagnosis

by Yan Zhang, Sai Bi, Qin Xu and Yingju Liu

Biosensors 2024, 14(10), 499; https://doi.org/10.3390/bios14100499 - 12 Oct 2024

Viewed by 411

Abstract

Biosensors are attractive tools for detecting molecules and small particles, as they can produce rapid, sensitive, and specific signals [...] Full article

(This article belongs to the Special Issue Biosensing and Diagnosis)

16 pages, 4570 KiB

Open AccessReview

Synthetic Microwave Focusing Techniques for Medical Imaging: Fundamentals, Limitations, and Challenges

by Younis M. Abbosh, Kamel Sultan, Lei Guo and Amin Abbosh

Biosensors 2024, 14(10), 498; https://doi.org/10.3390/bios14100498 - 12 Oct 2024

Viewed by 514

Abstract

Synthetic microwave focusing methods have been widely adopted in qualitative medical imaging to detect and localize anomalies based on their electromagnetic scattering signatures. This paper discusses the principles, challenges, and limitations of synthetic microwave-focusing techniques in medical applications. It is shown that the [...] Read more.

Synthetic microwave focusing methods have been widely adopted in qualitative medical imaging to detect and localize anomalies based on their electromagnetic scattering signatures. This paper discusses the principles, challenges, and limitations of synthetic microwave-focusing techniques in medical applications. It is shown that the various focusing techniques, including time reversal, confocal imaging, and delay-and-sum, are all based on the scalar solution of the electromagnetic scattering problem, assuming the imaged object, i.e., the tissue or object, is linear, reciprocal, and time-invariant. They all aim to generate a qualitative image, revealing any strong scatterer within the imaged domain. The differences among these techniques lie only in the assumptions made to derive the solution and create an image of the relevant tissue or object. To get a fast solution using limited computational resources, those methods assume the tissue is homogeneous and non-dispersive, and thus, a simplified far-field Green’s function is used. Some focusing methods compensate for dispersive effects and attenuation in lossy tissues. Other approaches replace the simplified Green’s function with more representative functions. While these focusing techniques offer benefits like speed and low computational requirements, they face significant ongoing challenges in real-life applications due to their oversimplified linear solutions to the complex problem of non-linear medical microwave imaging. This paper discusses these challenges and potential solutions. Full article

(This article belongs to the Section Biosensors and Healthcare)

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39 pages, 10199 KiB

Open AccessReview

Recent Advancements in MXene-Based Biosensors for Health and Environmental Applications—A Review

by Ashraf Ali, Sanjit Manohar Majhi, Lamia A. Siddig, Abdul Hakeem Deshmukh, Hongli Wen, Naser N. Qamhieh, Yaser E. Greish and Saleh T. Mahmoud

Biosensors 2024, 14(10), 497; https://doi.org/10.3390/bios14100497 - 12 Oct 2024

Viewed by 486

Abstract

Owing to their unique physicochemical properties, MXenes have emerged as promising materials for biosensing applications. This review paper comprehensively explores the recent advancements in MXene-based biosensors for health and environmental applications. This review begins with an introduction to MXenes and biosensors, outlining various [...] Read more.

Owing to their unique physicochemical properties, MXenes have emerged as promising materials for biosensing applications. This review paper comprehensively explores the recent advancements in MXene-based biosensors for health and environmental applications. This review begins with an introduction to MXenes and biosensors, outlining various types of biosensors including electrochemical, enzymatic, optical, and fluorescent-based systems. The synthesis methods and characteristics of MXenes are thoroughly discussed, highlighting the importance of these processes in tailoring MXenes for specific biosensing applications. Particular attention is given to the development of electrochemical MXene-based biosensors, which have shown remarkable sensitivity and selectivity in detecting various analytes. This review then delves into enzymatic MXene-based biosensors, exploring how the integration of MXenes with enzymes enhances sensor performance and expands the range of detectable biomarkers. Optical biosensors based on MXenes are examined, focusing on their mechanisms and applications in both healthcare and environmental monitoring. The potential of fluorescent-based MXene biosensors is also investigated, showcasing their utility in imaging and sensing applications. In addition, MXene-based potential wearable biosensors have been discussed along with the role of MXenes in volatile organic compound (VOC) detection for environmental applications. Finally, this paper concludes with a critical analysis of the current state of MXene-based biosensors and provides insights into future perspectives and challenges in this rapidly evolving field. Full article

(This article belongs to the Special Issue Nanotechnology-Enabled Biosensors)

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26 pages, 4155 KiB

Open AccessReview

Enhancing Sensitivity and Selectivity: Current Trends in Electrochemical Immunosensors for Organophosphate Analysis

by Yin Shen, Shichao Zhao, Fei Chen, Yanfei Lv and Li Fu

Biosensors 2024, 14(10), 496; https://doi.org/10.3390/bios14100496 - 12 Oct 2024

Viewed by 278

Abstract

This review examines recent advancements in electrochemical immunosensors for the detection of organophosphate pesticides, focusing on strategies to enhance sensitivity and selectivity. The widespread use of these pesticides has necessitated the development of rapid, accurate, and field-deployable detection methods. We discuss the fundamental [...] Read more.

This review examines recent advancements in electrochemical immunosensors for the detection of organophosphate pesticides, focusing on strategies to enhance sensitivity and selectivity. The widespread use of these pesticides has necessitated the development of rapid, accurate, and field-deployable detection methods. We discuss the fundamental principles of electrochemical immunosensors and explore innovative approaches to improve their performance. These include the utilization of nanomaterials such as metal nanoparticles, carbon nanotubes, and graphene for signal amplification; enzyme-based amplification strategies; and the design of three-dimensional electrode architectures. The integration of these sensors into microfluidic and lab-on-a-chip devices has enabled miniaturization and automation, while screen-printed and disposable electrodes have facilitated on-site testing. We analyze the challenges faced in real sample analysis, including matrix effects and the stability of biological recognition elements. Emerging trends such as the application of artificial intelligence for data interpretation and the development of aptamer-based sensors are highlighted. The review also considers the potential for commercialization and the hurdles that must be overcome for widespread adoption. Future research directions are identified, including the development of multi-analyte detection platforms and the integration of sensors with emerging technologies like the Internet of Things. This comprehensive overview provides insights into the current state of the field and outlines promising avenues for future development in organophosphate pesticide detection. Full article

(This article belongs to the Special Issue State-of-the-Art Biosensors in China (2nd Edition))

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25 pages, 3691 KiB

Open AccessReview

Metal–Organic Framework-Based Nanostructures for Electrochemical Sensing of Sweat Biomarkers

by Jing Meng, Moustafa Zahran and Xiaolin Li

Biosensors 2024, 14(10), 495; https://doi.org/10.3390/bios14100495 - 12 Oct 2024

Viewed by 721

Abstract

Sweat is considered the most promising candidate to replace conventional blood samples for noninvasive sensing. There are many tools and optical and electrochemical methods that can be used for detecting sweat biomarkers. Electrochemical methods are known for their simplicity and cost-effectiveness. However, they [...] Read more.

Sweat is considered the most promising candidate to replace conventional blood samples for noninvasive sensing. There are many tools and optical and electrochemical methods that can be used for detecting sweat biomarkers. Electrochemical methods are known for their simplicity and cost-effectiveness. However, they need to be optimized in terms of selectivity and catalytic activity. Therefore, electrode modifiers such as nanostructures and metal–organic frameworks (MOFs) or combinations of them were examined for boosting the performance of the electrochemical sensors. The MOF structures can be prepared by hydrothermal/solvothermal, sonochemical, microwave synthesis, mechanochemical, and electrochemical methods. Additionally, MOF nanostructures can be prepared by controlling the synthesis conditions or mixing bulk MOFs with nanoparticles (NPs). In this review, we spotlight the previously examined MOF-based nanostructures as well as promising ones for the electrochemical determination of sweat biomarkers. The presence of NPs strongly improves the electrical conductivity of MOF structures, which are known for their poor conductivity. Specifically, Cu-MOF and Co-MOF nanostructures were used for detecting sweat biomarkers with the lowest detection limits. Different electrochemical methods, such as amperometric, voltammetric, and photoelectrochemical, were used for monitoring the signal of sweat biomarkers. Overall, these materials are brilliant electrode modifiers for the determination of sweat biomarkers. Full article

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

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11 pages, 5333 KiB

Open AccessArticle

Fluorescence Immunoassay of Prostate-Specific Antigen Using 3D Paddle Screw-Type Devices and Their Rotating System

by Su Bin Han, Han Sol Kim, Young Ju Jo and Soo Suk Lee

Biosensors 2024, 14(10), 494; https://doi.org/10.3390/bios14100494 - 11 Oct 2024

Viewed by 388

Abstract

In this paper, we present a sensitive and highly reproducible fluorescence immunosensor for detecting PSA in human serum. A unique feature of this study is that it uses creatively designed paddle screw-type devices and their custom-made rotating system for PSA immunoassay. The paddle [...] Read more.

In this paper, we present a sensitive and highly reproducible fluorescence immunosensor for detecting PSA in human serum. A unique feature of this study is that it uses creatively designed paddle screw-type devices and their custom-made rotating system for PSA immunoassay. The paddle screw devices were designed to maximize the surface-to-volume ratio over which the immunoassay reaction could occur to improve detection sensitivity. This paddle screw-based immunoassay offers an accessible and efficient method with a short analysis time of less than 30 min. Active rotation of the paddle screw plays a crucial role in fast and accurate analysis of PSA. Additionally, a paddle screw-based immunoassay and subsequent fluorescence detection using a custom prototype fluorescence detection system were compared to a typical well plate-based immunoassay system. Results of PSA detection in human serum showed that the detection sensitivity through the paddle screw-based analysis improved about five times compared to that with a well plate-based analysis. Full article

(This article belongs to the Special Issue Nano Biosensors and Their Applications for In Vivo/Vitro Diagnosis—2nd Edition)

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12 pages, 2643 KiB

Open AccessArticle

Highly Sensitive Molecular Diagnostic Platform for Scrub Typhus Diagnosis Using O. tsutsugamushi Enrichment and Nucleic Acid Extraction

by Myoung Gyu Kim, Seulki Kim, Juho Jang, Jinkwan Lee, Namheon Kim, Yeji Yu, A Reum Kim, Seungjin Lim, Moonsuk Bae and Yong Shin

Biosensors 2024, 14(10), 493; https://doi.org/10.3390/bios14100493 - 10 Oct 2024

Viewed by 596

Abstract

Scrub typhus is caused by the Gram-negative obligate intracellular bacterium Orientia tsutsugamushi, and this tick-borne disease is difficult to distinguish from other acute febrile illnesses as it typically presents with symptoms such as rash, crusting at the bite site, headache, myalgia, lymphadenopathy, [...] Read more.

Scrub typhus is caused by the Gram-negative obligate intracellular bacterium Orientia tsutsugamushi, and this tick-borne disease is difficult to distinguish from other acute febrile illnesses as it typically presents with symptoms such as rash, crusting at the bite site, headache, myalgia, lymphadenopathy, and elevated liver transaminases. It can often be diagnosed clinically, but not all patients present with characteristic symptoms, so serological diagnosis and molecular techniques may be required. However, existing diagnostic tests often have low sensitivity and specificity, making early detection difficult. This study presents a nucleic acid extraction method using large volumes of plasma and buffy coat to increase sensitivity, as well as an improved detection method using two target genes. Using the I-PULL device, nucleic acids can be extracted from up to 4 mL of sample in 30 min, avoiding contamination. The extracted DNA detects two genes of O. tsutsugamushi, increasing sensitivity compared to single-gene detection. Clinical validation in 38 patient samples showed 100% specificity and 95.24% sensitivity for the single target gene, with specificity and sensitivity rising to 100% when both genes are analyzed. This molecular diagnostic platform can be useful for distinguishing scrub typhus from similar diseases. Full article

(This article belongs to the Special Issue Development of Point-of-Care Diagnostic Tools and New Bioassays)

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24 pages, 12425 KiB

Open AccessReview

Metal Organic Frameworks Based Wearable and Point-of-Care Electrochemical Sensors for Healthcare Monitoring

by K Theyagarajan and Young-Joon Kim

Biosensors 2024, 14(10), 492; https://doi.org/10.3390/bios14100492 - 10 Oct 2024

Viewed by 581

Abstract

The modern healthcare system strives to provide patients with more comfortable and less invasive experiences, focusing on noninvasive and painless diagnostic and treatment methods. A key priority is the early diagnosis of life-threatening diseases, which can significantly improve patient outcomes by enabling treatment [...] Read more.

The modern healthcare system strives to provide patients with more comfortable and less invasive experiences, focusing on noninvasive and painless diagnostic and treatment methods. A key priority is the early diagnosis of life-threatening diseases, which can significantly improve patient outcomes by enabling treatment at earlier stages. While most patients must undergo diagnostic procedures before beginning treatment, many existing methods are invasive, time-consuming, and inconvenient. To address these challenges, electrochemical-based wearable and point-of-care (PoC) sensing devices have emerged, playing a crucial role in the noninvasive, continuous, periodic, and remote monitoring of key biomarkers. Due to their numerous advantages, several wearable and PoC devices have been developed. In this focused review, we explore the advancements in metal–organic frameworks (MOFs)-based wearable and PoC devices. MOFs are porous crystalline materials that are cost-effective, biocompatible, and can be synthesized sustainably on a large scale, making them promising candidates for sensor development. However, research on MOF-based wearable and PoC sensors remains limited, and no comprehensive review has yet to synthesize the existing knowledge in this area. This review aims to fill that gap by emphasizing the design of materials, fabrication methodologies, sensing mechanisms, device construction, and real-world applicability of these sensors. Additionally, we underscore the importance and potential of MOF-based wearable and PoC sensors for advancing healthcare technologies. In conclusion, this review sheds light on the current state of the art, the challenges faced, and the opportunities ahead in MOF-based wearable and PoC sensing technologies. Full article

(This article belongs to the Special Issue Wearable Bio/Chemical Sensors for Healthcare Monitoring)

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12 pages, 3170 KiB

Open AccessArticle

Mycotoxin Detection through Colorimetric Immunoprobing with Gold Nanoparticle Antibody Conjugates

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

Biosensors 2024, 14(10), 491; https://doi.org/10.3390/bios14100491 - 10 Oct 2024

Viewed by 467

Abstract

Driven by their exceptional optical characteristics, robust chemical stability, and facile bioconjugation, gold nanoparticles (AuNPs) have emerged as a preferred material for detection and biosensing applications in scientific research. This study involves the development of a simple, rapid, and cost-effective colorimetric immuno-sensing probe [...] Read more.

Driven by their exceptional optical characteristics, robust chemical stability, and facile bioconjugation, gold nanoparticles (AuNPs) have emerged as a preferred material for detection and biosensing applications in scientific research. This study involves the development of a simple, rapid, and cost-effective colorimetric immuno-sensing probe to detect aflatoxin B1 and zearalenone using AuNP antibody (AuNP-mAb) conjugates. Anti-toxin antibodies were attached to the AuNPs by using the physical adsorption method. The colorimetric immunosensor developed operates on the principle that the optical properties of the AuNP are very sensitive to aggregation, which can be induced by a critical high salt concentration. Although the presence of antibodies on the AuNP surface inhibits the aggregation, these antibodies bind to the toxin with higher affinity, which leads to exposure of the surface of AuNPs and aggregation in a salt environment. The aggregation triggers a noticeable but variable alteration in color from red to purple and blueish gray, as a result of a red shift in the surface plasmon resonance band of the AuNPs. The extent of the shift is dependent on the toxin exposure dose and can be quantified using a calibration curve through UV–Visible–NIR spectroscopy. The limit of detection using this assay was determined to be as low as 0.15 ng/mL for both zearalenone and aflatoxin B1. The specificity of the prepared immunoprobe was analyzed for a particular mycotoxin in the presence of other mycotoxins. The developed immunoprobe was evaluated for real-world applicability using artificially spiked samples. This colorimetric immunoprobe based on localized surface plasmon resonance (LSPR) has a reduced detection limit compared to other immunoassays, a rapid readout, low cost, and facile fabrication. Full article

(This article belongs to the Special Issue Biosensors for the Analysis and Detection of Drug, Food or Disease)

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22 pages, 10435 KiB

Open AccessReview

Review of Liquid Metal Fiber Based Biosensors and Bioelectronics

by Xiaotong Liu, Hui Xu, Jiameng Li, Yanqing Liu and Haojun Fan

Biosensors 2024, 14(10), 490; https://doi.org/10.3390/bios14100490 - 9 Oct 2024

Viewed by 684

Abstract

Liquid metal, as a novel material, has become ideal for the fabrication of flexible conductive fibers and has shown great potential in the field of biomedical sensing. This paper presents a comprehensive review of the unique properties of liquid metals such as gallium-based [...] Read more.

Liquid metal, as a novel material, has become ideal for the fabrication of flexible conductive fibers and has shown great potential in the field of biomedical sensing. This paper presents a comprehensive review of the unique properties of liquid metals such as gallium-based alloys, including their excellent electrical conductivity, mobility, and biocompatibility. These properties make liquid metals ideal for the fabrication of flexible and malleable biosensors. The article explores common preparation methods for liquid metal conductive fibers, such as internal liquid metal filling, surface printing with liquid metal, and liquid metal coating techniques, and their applications in health monitoring, neural interfaces, and wearable devices. By summarizing and analyzing the current research, this paper aims to reveal the current status and challenges of liquid metal conductive fibers in the field of biosensors and to look forward to their development in the future, which will provide valuable references and insights for researchers in the field of biomedical engineering. Full article

(This article belongs to the Special Issue Advanced Biosensors and Bioelectronics: From Liquid Metal-Based to Flexible Devices)

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12 pages, 1482 KiB

Open AccessArticle

Non-Invasive On–Off Fluorescent Biosensor for Endothelial Cell Detection

by Qingyun Jiang, Shuai Shao, Na Li, Zhengyao Zhang and Bo Liu

Biosensors 2024, 14(10), 489; https://doi.org/10.3390/bios14100489 - 9 Oct 2024

Viewed by 540

Abstract

For rapid and convenient detection of living endothelial cells (ECs) specifically without immunostaining, we developed a biosensor based on turn-on fluorescent protein, named LV-EcpG. It includes a high-affinity peptide E12P obtained through phage display technology for specifically recognizing ECs and a turn-on EGFP [...] Read more.

For rapid and convenient detection of living endothelial cells (ECs) specifically without immunostaining, we developed a biosensor based on turn-on fluorescent protein, named LV-EcpG. It includes a high-affinity peptide E12P obtained through phage display technology for specifically recognizing ECs and a turn-on EGFP fused with two linker peptides. The “on-off” switching mechanism of this genetically encoded fluorescent protein-based biosensor (FPB) ensured that fluorescence signals were activated only when binding with ECs, thus enabling these FPB characters for direct, visual, and non-invasive detection of ECs. Its specificity and multicolor imaging capability established LV-EcpG as a powerful tool for live EC research, with significant potential for diagnosing and treating cardiovascular diseases and tumor angiogenesis. Full article

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

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13 pages, 8057 KiB

Open AccessCommunication

ZnS and Reduced Graphene Oxide Nanocomposite-Based Non-Enzymatic Biosensor for the Photoelectrochemical Detection of Uric Acid

by Yao Zhao, Niancai Peng, Weizhuo Gao, Fei Hu, Chuanyu Zhang and Xueyong Wei

Biosensors 2024, 14(10), 488; https://doi.org/10.3390/bios14100488 - 8 Oct 2024

Viewed by 402

Abstract

In this work, we report a study of a zinc sulfide (ZnS) nanocrystal and reduced graphene oxide (RGO) nanocomposite-based non-enzymatic uric acid biosensor. ZnS nanocrystals with different morphologies were synthesized through a hydrothermal method, and both pure nanocrystals and related ZnS/RGO were characterized [...] Read more.

In this work, we report a study of a zinc sulfide (ZnS) nanocrystal and reduced graphene oxide (RGO) nanocomposite-based non-enzymatic uric acid biosensor. ZnS nanocrystals with different morphologies were synthesized through a hydrothermal method, and both pure nanocrystals and related ZnS/RGO were characterized with SEM, XRD and an absorption spectrum and resistance test. It was found that compared to ZnS nanoparticles, the ZnS nanoflakes had stronger UV light absorption ability at the wavelength of 280 nm of UV light. The RGO significantly enhanced the electron transfer efficiency of the ZnS nanoflakes, which further led to a better photoelectrochemical property of the ZnS/RGO nanocomposites. The ZnS nanoflake/RGO nanocomposite-based biosensor showed an excellent uric acid detecting sensitivity of 534.5 μA·cm⁻²·mM⁻¹ in the linear range of 0.01 to 2 mM and a detection limit of 0.048 μM. These results will help to improve non-enzymatic biosensor properties for the rapid and accurate clinical detection of uric acid. Full article

(This article belongs to the Special Issue Biosensing Technologies in Medical Diagnosis)

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9 pages, 1078 KiB

Open AccessBrief Report

Paralytic Shellfish Toxin Extraction from Bivalve Meat for Analysis Using Potentiometric Chemical Sensors

by Ana Filipa R. Cerqueira, Catarina Moreirinha, Mariana Raposo, Maria Teresa S. R. Gomes, Sara T. Costa, Maria João Botelho and Alisa Rudnitskaya

Biosensors 2024, 14(10), 487; https://doi.org/10.3390/bios14100487 - 8 Oct 2024

Viewed by 413

Abstract

A simple and reliable methodology for the detection of paralytic shellfish toxins (PSTs) in bivalve tissues using potentiometric chemical sensors was developed. Five methods of PST extraction from mussel and oyster tissues were evaluated, including the AOAC-recommended method, which served as the reference. [...] Read more.

A simple and reliable methodology for the detection of paralytic shellfish toxins (PSTs) in bivalve tissues using potentiometric chemical sensors was developed. Five methods of PST extraction from mussel and oyster tissues were evaluated, including the AOAC-recommended method, which served as the reference. The main objective was to minimize the matrix effect of the extracts on the sensors’ responses and ensure efficient toxin recovery. Extraction procedures using acetic acid with heating and water yielded the highest responses from the potentiometric chemical sensors to PSTs. The highest recovery of PSTs from bivalve tissues was achieved with extraction using acetic acid and heating. Further extract purification, which is indispensable for liquid chromatography with fluorometric detection (LC-FLD) analysis, was found to be unnecessary for analysis with chemical sensors. While water extraction can also be used as a rapid and simple PST extraction method, the lower recoveries should be considered when interpreting the results. Further research is needed to identify the compounds remaining in the extracts that cause a decrease in sensor responses and to develop procedures for their elimination. Full article

(This article belongs to the Special Issue Feature Paper in Biosensor and Bioelectronic Devices 2024)

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10 pages, 1238 KiB

Open AccessArticle

Noninvasive Monitoring of Glycemia Level in Diabetic Patients by Wearable Advanced Biosensors

by Elena V. Daboss, Maria A. Komkova, Vita N. Nikitina, Egor A. Andreev, Darya V. Vokhmyanina and Arkady A. Karyakin

Biosensors 2024, 14(10), 486; https://doi.org/10.3390/bios14100486 - 8 Oct 2024

Viewed by 603

Abstract

We report on the possibility of noninvasive diabetes monitoring through continuous analysis of sweat. The prediction of the blood glucose level in diabetic patients is possible on the basis of their sweat glucose content due to the positive correlation discovered. The ratio between [...] Read more.

We report on the possibility of noninvasive diabetes monitoring through continuous analysis of sweat. The prediction of the blood glucose level in diabetic patients is possible on the basis of their sweat glucose content due to the positive correlation discovered. The ratio between the blood glucose and sweat glucose concentrations for a certain diabetic subject is stable within weeks, excluding requirements for frequent blood probing. The glucose variations in sweat display allometric (non-linear) dependence on those in blood, allowing more precise blood glucose estimation. Selective (avoiding false-positive responses) and sensitive (sweat glucose is on average 30–50 times lower) detection is possible with biosensors based on the glucose oxidase enzyme coupled with a Prussian Blue transducer. Reliable glucose detection in just secreted sweat would allow noninvasive monitoring of the glycemia level in diabetic patients. Full article

(This article belongs to the Special Issue Feature Paper in Biosensor and Bioelectronic Devices 2024)

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Graphical abstract

13 pages, 3048 KiB

Open AccessArticle

Paper-Based DNA Biosensor for Rapid and Selective Detection of miR-21

by Alexander Hunt, Sri Ramulu Torati and Gymama Slaughter

Biosensors 2024, 14(10), 485; https://doi.org/10.3390/bios14100485 - 8 Oct 2024

Viewed by 668

Abstract

Cancer is the second leading cause of death globally, with 9.7 million fatalities in 2022. While routine screenings are vital for early detection, healthcare disparities persist, highlighting the need for equitable solutions. Recent advancements in cancer biomarker identification, particularly microRNAs (miRs), have improved [...] Read more.

Cancer is the second leading cause of death globally, with 9.7 million fatalities in 2022. While routine screenings are vital for early detection, healthcare disparities persist, highlighting the need for equitable solutions. Recent advancements in cancer biomarker identification, particularly microRNAs (miRs), have improved early detection. MiR-21 is notably overexpressed in various cancers and can be a valuable diagnostic tool. Traditional detection methods, though accurate, are costly and complex, limiting their use in resource-limited settings. Paper-based electrochemical biosensors offer a promising alternative, providing cost-effective, sensitive, and rapid diagnostics suitable for point-of-care use. This study introduces an innovative electrochemical paper-based biosensor that leverages gold inkjet printing for the quantitative detection of miR-21. The biosensor, aimed at developing cost-effective point-of-care devices for low-resource settings, uses thiolated self-assembled monolayers to immobilize single-stranded DNA-21 (ssDNA-21) on electrodeposited gold nanoparticles (AuNPs) on the printed gold surface, facilitating specific miR-21 capture. The hybridization of ssDNA-21 with miR-21 increases the anionic barrier density, impeding electron transfer from the redox probe and resulting in a current suppression that correlates with miR-21 concentration. The biosensor exhibited a linear detection range from 1 fM to 1 nM miR-21 with a sensitivity of 7.69 fM µA⁻¹ cm² and a rapid response time (15 min). With a low detection limit of 0.35 fM miR-21 in serum, the biosensor also demonstrates excellent selectivity against interferent species. This study introduces an electrochemical paper-based biosensor that uses gold inkjet printing to precisely detect miR-21, a key biomarker overexpressed in various cancers. This innovative device highlights the potential for cost-effective, accessible cancer diagnostics in underserved areas. Full article

(This article belongs to the Special Issue Nano Biosensors and Their Applications for In Vivo/Vitro Diagnosis—2nd Edition)

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17 pages, 13470 KiB

Open AccessArticle

Hydrocarbonoclastic Biofilm-Based Microbial Fuel Cells: Exploiting Biofilms at Water-Oil Interface for Renewable Energy and Wastewater Remediation

by Nicola Lovecchio, Roberto Giuseppetti, Lucia Bertuccini, Sandra Columba-Cabezas, Valentina Di Meo, Mario Figliomeni, Francesca Iosi, Giulia Petrucci, Michele Sonnessa, Fabio Magurano and Emilio D’Ugo

Biosensors 2024, 14(10), 484; https://doi.org/10.3390/bios14100484 - 8 Oct 2024

Viewed by 515

Abstract

Microbial fuel cells (MFCs) represent a promising technology for sustainable energy generation, which leverages the metabolic activities of microorganisms to convert organic substrates into electrical energy. In oil spill scenarios, hydrocarbonoclastic biofilms naturally form at the water–oil interface, creating a distinct environment for [...] Read more.

Microbial fuel cells (MFCs) represent a promising technology for sustainable energy generation, which leverages the metabolic activities of microorganisms to convert organic substrates into electrical energy. In oil spill scenarios, hydrocarbonoclastic biofilms naturally form at the water–oil interface, creating a distinct environment for microbial activity. In this work, we engineered a novel MFC that harnesses these biofilms by strategically positioning the positive electrode at this critical junction, integrating the biofilm’s natural properties into the MFC design. These biofilms, composed of specialized hydrocarbon-degrading bacteria, are vital in supporting electron transfer, significantly enhancing the system’s power generation. Next-generation sequencing and scanning electron microscopy were used to characterize the microbial community, revealing a significant enrichment of hydrocarbonoclastic Gammaproteobacteria within the biofilm. Notably, key genera such as Paenalcaligenes, Providencia, and Pseudomonas were identified as dominant members, each contributing to the degradation of complex hydrocarbons and supporting the electrogenic activity of the MFCs. An electrochemical analysis demonstrated that the MFC achieved a stable power output of 51.5 μW under static conditions, with an internal resistance of about 1.05 kΩ. The system showed remarkable long-term stability, which maintained consistent performance over a 5-day testing period, with an average daily energy storage of approximately 216 mJ. Additionally, the MFC effectively recovered after deep discharge cycles, sustaining power output for up to 7.5 h before requiring a recovery period. Overall, the study indicates that MFCs based on hydrocarbonoclastic biofilms provide a dual-functionality system, combining renewable energy generation with environmental remediation, particularly in wastewater treatment. Despite lower power output compared to other hydrocarbon-degrading MFCs, the results highlight the potential of this technology for autonomous sensor networks and other low-power applications, which required sustainable energy sources. Moreover, the hydrocarbonoclastic biofilm-based MFC presented here offer significant potential as a biosensor for real-time monitoring of hydrocarbons and other contaminants in water. The biofilm’s electrogenic properties enable the detection of organic compound degradation, positioning this system as ideal for environmental biosensing applications. Full article

(This article belongs to the Special Issue Microbial Biosensor: From Design to Applications)

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25 pages, 14822 KiB

Open AccessReview

Tear-Based Ocular Wearable Biosensors for Human Health Monitoring

by Arunima Rajan, Jithin Vishnu and Balakrishnan Shankar

Biosensors 2024, 14(10), 483; https://doi.org/10.3390/bios14100483 - 8 Oct 2024

Viewed by 899

Abstract

Wearable tear-based biosensors have garnered substantial interest for real time monitoring with an emphasis on personalized health care. These biosensors utilize major tear biomarkers such as proteins, lipids, metabolites, and electrolytes for the detection and recording of stable biological signals in a non-invasive [...] Read more.

Wearable tear-based biosensors have garnered substantial interest for real time monitoring with an emphasis on personalized health care. These biosensors utilize major tear biomarkers such as proteins, lipids, metabolites, and electrolytes for the detection and recording of stable biological signals in a non-invasive manner. The present comprehensive review delves deep into the tear composition along with potential biomarkers that can identify, monitor, and predict certain ocular diseases such as dry eye disease, conjunctivitis, eye-related infections, as well as diabetes mellitus. Recent technologies in tear-based wearable point-of-care medical devices, specifically the state-of-the-art and prospects of glucose, pH, lactate, protein, lipid, and electrolyte sensing from tear are discussed. Finally, the review addresses the existing challenges associated with the widespread application of tear-based sensors, which will pave the way for advanced scientific research and development of such non-invasive health monitoring devices. Full article

(This article belongs to the Special Issue Recent Advances in Wearable Biosensors for Human Health Monitoring)

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20 pages, 6698 KiB

Open AccessArticle

A Low-Cost, Portable, Multi-Cancer Screening Device Based on a Ratio Fluorometry and Signal Correlation Technique

by Abdulaziz S. Alghamdi and Rabah W. Aldhaheri

Biosensors 2024, 14(10), 482; https://doi.org/10.3390/bios14100482 - 7 Oct 2024

Viewed by 811

Abstract

The autofluorescence of erythrocyte porphyrins has emerged as a potential method for multi-cancer early detection (MCED). With this method’s dependence on research-grade spectrofluorometers, significant improvements in instrumentation are necessary to translate its potential into clinical practice, as with any promising medical technology. To [...] Read more.

The autofluorescence of erythrocyte porphyrins has emerged as a potential method for multi-cancer early detection (MCED). With this method’s dependence on research-grade spectrofluorometers, significant improvements in instrumentation are necessary to translate its potential into clinical practice, as with any promising medical technology. To fill this gap, in this paper, we present an automated ratio porphyrin analyzer for cancer screening (ARPA-CS), a low-cost, portable, and automated instrument for MCED via the ratio fluorometry of porphyrins. The ARPA-CS aims to facilitate cancer screening in an inexpensive, rapid, non-invasive, and reasonably accurate manner for use in primary clinics or at point of care. To accomplish this, the ARPA-CS uses an ultraviolet-excited optical apparatus for ratio fluorometry that features two photodetectors for detection at 590 and 630 nm. Additionally, it incorporates a synchronous detector for the precision measurement of signals based on the Walsh-ordered Walsh–Hadamard transform (WHT)_w and circular shift. To estimate its single-photodetector capability, we established a linear calibration curve for the ARBA-CS exceeding four orders of magnitude with a linearity of up to 0.992 and a low detection limit of 0.296 µg/mL for riboflavin. The ARPA-CS also exhibited excellent repeatability (0.21%) and stability (0.60%). Moreover, the ratio fluorometry of three serially diluted standard solutions of riboflavin yielded a ratio of 0.4, which agrees with that expected based on the known emission spectra of riboflavin. Additionally, the ratio fluorometry of the porphyrin solution yielded a ratio of 49.82, which was ascribed to the predominant concentration of protoporphyrin IX in the brown eggshells, as confirmed in several studies. This study validates this instrument for the ratio fluorometry of porphyrins as a biomarker for MCED. Nevertheless, large and well-designed clinical trials are necessary to further elaborate more on this matter. Full article

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

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