Biosensors

11 pages, 3188 KiB

Open AccessArticle

A Novel Ferrocene-Linked Thionine as a Dual Redox Mediator for the Electrochemical Detection of Dopamine and Hydrogen Peroxide

by Manikandan Palinci Nagarajan, Manikandan Ramalingam, Ilakeya Subbiah Arivuthilagam, Vishwa Paramaguru, Md. Mahbubur Rahman, Jongdeok Park, Francis Kwaku Asiam, Byungjik Lee, Kwang Pyo Kim and Jae-Joon Lee

Biosensors 2024, 14(9), 448; https://doi.org/10.3390/bios14090448 - 19 Sep 2024

Abstract

We introduce a novel dual redox mediator synthesized by covalently linking ferrocene dicarboxylic acid (FcDA) and thionine (TH) onto a pre-treated glassy carbon electrode. This unique structure significantly enhances the electro-oxidation of dopamine (DA) and the reduction of hydrogen peroxide (H₂O [...] Read more.

We introduce a novel dual redox mediator synthesized by covalently linking ferrocene dicarboxylic acid (FcDA) and thionine (TH) onto a pre-treated glassy carbon electrode. This unique structure significantly enhances the electro-oxidation of dopamine (DA) and the reduction of hydrogen peroxide (H₂O₂), offering a sensitive detection method for both analytes. The electrode exhibits exceptional sensitivity, selectivity, and stability, demonstrating potential for practical applications in biosensing. It facilitates rapid electron transfer between the analyte and the electrode surface, detecting H₂O₂ concentrations ranging from 1.5 to 60 µM with a limit of detection (LoD) of 0.49 µM and DA concentrations from 0.3 to 230 µM with an LoD of 0.07 µM. The electrode’s performance was validated through real-sample analyses, yielding satisfactory results. Full article

(This article belongs to the Special Issue Nanomaterial-Based Biosensors to Support the One Health Concept)

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5 pages, 176 KiB

Open AccessEditorial

Editorial to the Special Issue “Advances in Optical Biosensors and Chemical Sensors”

by Flavio Esposito, Stefania Campopiano and Agostino Iadicicco

Biosensors 2024, 14(9), 447; https://doi.org/10.3390/bios14090447 - 19 Sep 2024

Abstract

Optical biosensors and optical chemical sensors are innovative analytical tools that utilize light-based techniques to detect and quantify a plethora of biological and chemical substances [...] Full article

(This article belongs to the Special Issue Advances in Optical Biosensors and Chemical Sensors)

14 pages, 1913 KiB

Open AccessArticle

Ultrasensitive Electrochemical Biosensors Based on Allosteric Transcription Factors (aTFs) for Pb²⁺ Detection

by Ningkang Yu, Chen Zhao, Xiaodan Kang, Cheng Zhang, Xi Zhang, Chenyu Li, Shang Wang, Bin Xue, Xiaobo Yang, Chao Li, Zhigang Qiu, Jingfeng Wang and Zhiqiang Shen

Biosensors 2024, 14(9), 446; https://doi.org/10.3390/bios14090446 - 18 Sep 2024

Abstract

Exposure to Pb²⁺ in the environment, especially in water, poses a significant threat to human health and urgently necessitates the development of highly sensitive Pb²⁺ detection methods. In this study, we have integrated the high sensitivity of electrochemical techniques with allosteric [...] Read more.

Exposure to Pb²⁺ in the environment, especially in water, poses a significant threat to human health and urgently necessitates the development of highly sensitive Pb²⁺ detection methods. In this study, we have integrated the high sensitivity of electrochemical techniques with allosteric transcription factors (aTFs) to develop an innovative electrochemical biosensing platform. This biosensors leverage the specific binding and dissociation of DNA to the aTFs (PbrR) on electrode surfaces to detect Pb²⁺. Under the optimal conditions, the platform has a broad linear detection range from 1 pM to 10 nM and an exceptionally low detection threshold of 1 pM, coupled with excellent selectivity for Pb²⁺. Notably, the biosensor demonstrates regenerative capabilities, enabling up to five effective Pb²⁺ measurements. After one week of storage at 4 °C, effective lead ion detection was still possible, demonstrating the biosensor’s excellent stability, this can effectively save the cost of detection. The biosensor also achieves a recovery rate of 93.3% to 106.6% in real water samples. The biosensor shows its potential as a robust tool for the ultrasensitive detection of Pb²⁺ in environmental monitoring. Moreover, this research provides new insights into the future applications of aTFs in electrochemical sensing. Full article

(This article belongs to the Section Environmental Biosensors and Biosensing)

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12 pages, 3242 KiB

Open AccessArticle

Electrochemical Impedance Spectroscopy-Based Microfluidic Biosensor Using Cell-Imprinted Polymers for Bacteria Detection

by Shiva Akhtarian, Satinder Kaur Brar and Pouya Rezai

Biosensors 2024, 14(9), 445; https://doi.org/10.3390/bios14090445 - 18 Sep 2024

Abstract

The rapid and sensitive detection of bacterial contaminants using low-cost and portable point-of-need (PoN) biosensors has gained significant interest in water quality monitoring. Cell-imprinted polymers (CIPs) are emerging as effective and inexpensive materials for bacterial detection as they provide specific binding sites designed [...] Read more.

The rapid and sensitive detection of bacterial contaminants using low-cost and portable point-of-need (PoN) biosensors has gained significant interest in water quality monitoring. Cell-imprinted polymers (CIPs) are emerging as effective and inexpensive materials for bacterial detection as they provide specific binding sites designed to capture whole bacterial cells, especially when integrated into PoN microfluidic devices. However, improving the sensitivity and detection limits of these sensors remains challenging. In this study, we integrated CIP-functionalized stainless steel microwires (CIP-MWs) into a microfluidic device for the impedimetric detection of E. coli bacteria. The sensor featured two parallel microchannels with three-electrode configurations that allowed simultaneous control and electrochemical impedance spectroscopy (EIS) measurements. A CIP-MW and a non-imprinted polymer (NIP)-MW suspended perpendicular to the microchannels served as the working electrodes in the test and control channels, respectively. Electrochemical spectra were fitted with equivalent electrical circuits, and the charge transfer resistances of both cells were measured before and after incubation with target bacteria. The charge transfer resistance of the CIP-MWs after 30 min of incubation with bacteria was increased. By normalizing the change in charge transfer resistance and analyzing the dose–response curve for bacterial concentrations ranging from 0 to 10⁷ CFU/mL, we determined the limits of detection and quantification as 2 × 10² CFU/mL and 1.4 × 10⁴ CFU/mL, respectively. The sensor demonstrated a dynamic range of 10² to 10⁷ CFU/mL, where bacterial counts were statistically distinguishable. The proposed sensor offers a sensitive, cost-effective, durable, and rapid solution for on-site identification of waterborne pathogens. Full article

(This article belongs to the Special Issue Molecularly Imprinted Polymer Based Biosensors for Environmental, Agricultural and Food Safety Applications)

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20 pages, 3010 KiB

Open AccessArticle

Salmonella Detection in Food Using a HEK-hTLR5 Reporter Cell-Based Sensor

by Esma Eser, Victoria A. Felton, Rishi Drolia and Arun K. Bhunia

Biosensors 2024, 14(9), 444; https://doi.org/10.3390/bios14090444 - 18 Sep 2024

Abstract

The development of a rapid, sensitive, specific method for detecting foodborne pathogens is paramount for supplying safe food to enhance public health safety. Despite the significant improvement in pathogen detection methods, key issues are still associated with rapid methods, such as distinguishing living [...] Read more.

The development of a rapid, sensitive, specific method for detecting foodborne pathogens is paramount for supplying safe food to enhance public health safety. Despite the significant improvement in pathogen detection methods, key issues are still associated with rapid methods, such as distinguishing living cells from dead, the pathogenic potential or health risk of the analyte at the time of consumption, the detection limit, and the sample-to-result. Mammalian cell-based assays analyze pathogens’ interaction with host cells and are responsive only to live pathogens or active toxins. In this study, a human embryonic kidney (HEK293) cell line expressing Toll-Like Receptor 5 (TLR-5) and chromogenic reporter system (HEK dual hTLR5) was used for the detection of viable Salmonella in a 96-well tissue culture plate. This cell line responds to low concentrations of TLR5 agonist flagellin. Stimulation of TLR5 ligand activates nuclear factor-kB (NF-κB)—linked alkaline phosphatase (AP-1) signaling cascade inducing the production of secreted embryonic alkaline phosphatase (SEAP). With the addition of a ρ-nitrophenyl phosphate as a substrate, a colored end product representing a positive signal is quantified. The assay’s specificity was validated with the top 20 Salmonella enterica serovars and 19 non-Salmonella spp. The performance of the assay was also validated with spiked food samples. The total detection time (sample-to-result), including shortened pre-enrichment (4 h) and selective enrichment (4 h) steps with artificially inoculated outbreak-implicated food samples (chicken, peanut kernel, peanut butter, black pepper, mayonnaise, and peach), was 15 h when inoculated at 1–100 CFU/25 g sample. These results show the potential of HEK-Dual^TM hTLR5 cell-based functional biosensors for the rapid screening of Salmonella. Full article

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

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19 pages, 5389 KiB

Open AccessReview

Recent Electrochemical Advancements for Liquid-Biopsy Nucleic Acid Detection for Point-of-Care Prostate Cancer Diagnostics and Prognostics

by Joseph Broomfield, Melpomeni Kalofonou, Charlotte L. Bevan and Pantelis Georgiou

Biosensors 2024, 14(9), 443; https://doi.org/10.3390/bios14090443 - 14 Sep 2024

Abstract

Current diagnostic and prognostic tests for prostate cancer require specialised laboratories and have low specificity for prostate cancer detection. As such, recent advancements in electrochemical devices for point of care (PoC) prostate cancer detection have seen significant interest. Liquid-biopsy detection of relevant circulating [...] Read more.

Current diagnostic and prognostic tests for prostate cancer require specialised laboratories and have low specificity for prostate cancer detection. As such, recent advancements in electrochemical devices for point of care (PoC) prostate cancer detection have seen significant interest. Liquid-biopsy detection of relevant circulating and exosomal nucleic acid markers presents the potential for minimally invasive testing. In combination, electrochemical devices and circulating DNA and RNA detection present an innovative approach for novel prostate cancer diagnostics, potentially directly within the clinic. Recent research in electrochemical impedance spectroscopy, voltammetry, chronoamperometry and potentiometric sensing using field-effect transistors will be discussed. Evaluation of the PoC relevance of these techniques and their fulfilment of the WHO’s REASSURED criteria for medical diagnostics is described. Further areas for exploration within electrochemical PoC testing and progression to clinical implementation for prostate cancer are assessed. Full article

(This article belongs to the Special Issue Lab-on-a-Chip Devices for Point-of-Care Diagnostics)

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11 pages, 1982 KiB

Open AccessArticle

Paper-Based Microfluidic Device for Extracellular Lactate Detection

by Yan Nan, Peng Zuo and Bangce Ye

Biosensors 2024, 14(9), 442; https://doi.org/10.3390/bios14090442 - 14 Sep 2024

Abstract

Lactate is a critical regulatory factor secreted by tumors, influencing tumor development, metastasis, and clinical prognosis. Precise analysis of tumor-cell-secreted lactate is pivotal for early cancer diagnosis. This study describes a paper-based microfluidic chip to enable the detection of lactate levels secreted externally [...] Read more.

Lactate is a critical regulatory factor secreted by tumors, influencing tumor development, metastasis, and clinical prognosis. Precise analysis of tumor-cell-secreted lactate is pivotal for early cancer diagnosis. This study describes a paper-based microfluidic chip to enable the detection of lactate levels secreted externally by living cells. Under optimized conditions, the lactate biosensor can complete the assay in less than 30 min. In addition, the platform can be used to distinguish lactate secretion levels in different cell lines and can be applied to the screening of antitumor drugs. Through enzymatic chemical conversion, this platform generates fluorescent signals, enabling qualitative assessment under a handheld UV lamp and quantitative analysis via grayscale intensity measurements using ImageJ (Ver. 1.50i) software. The paper-based platform presented in this study is rapid and highly sensitive and does not necessitate other costly and intricate instruments, thus making it applicable in resource-constrained areas and serving as a valuable tool for investigating cell lactate secretion and screening various anti-cancer drugs. Full article

(This article belongs to the Special Issue Application of Microfluidics in Cell Manipulation and Biosensing)

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12 pages, 3019 KiB

Open AccessArticle

Analysis of Random Lasing in Human Blood

by Sergio de Armas-Rillo, Beatriz Abdul-Jalbar, Josmar Salas-Hernández, Jose María Raya-Sánchez, Tomás González-Hernández and Fernando Lahoz

Biosensors 2024, 14(9), 441; https://doi.org/10.3390/bios14090441 - 13 Sep 2024

Abstract

Random lasing (RL) is an optical phenomenon that arises from the combination of light amplification with optical feedback through multiple scattering events. In this paper, we present our investigations of RL generation from human blood samples. We tested mixtures of rhodamine B dye [...] Read more.

Random lasing (RL) is an optical phenomenon that arises from the combination of light amplification with optical feedback through multiple scattering events. In this paper, we present our investigations of RL generation from human blood samples. We tested mixtures of rhodamine B dye solutions with different blood components, including platelets, lymphocytes, erythrocytes, and whole blood. Intense coherent RL was obtained in all cases at relatively low pump thresholds, except for erythrocytes. We also studied the potential of RL signal analysis for biosensing applications using blood samples from healthy individuals and patients suffering from Chronic Lymphocytic Leukemia (CLL). CLL is a blood disease characterized by a high count of lymphocytes with significant morphological changes. A statistical analysis of the RL spectra based on principal component and linear discriminant analyses was conducted for classification purposes. RL-based sample discrimination was conducted for whole blood, platelet, and lymphocyte samples, being especially successful (86.7%) for the latter. Our results highlight the potential of RL analysis as a sensing tool in blood. Full article

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

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10 pages, 3134 KiB

Open AccessCommunication

All-Dielectric Metasurface-Based Terahertz Molecular Fingerprint Sensor for Trace Cinnamoylglycine Detection

by Qiyuan Xu, Mingjun Sun, Weijin Wang and Yanpeng Shi

Biosensors 2024, 14(9), 440; https://doi.org/10.3390/bios14090440 - 13 Sep 2024

Abstract

Terahertz (THZ) spectroscopy has emerged as a superior label-free sensing technology in the detection, identification, and quantification of biomolecules in various biological samples. However, the limitations in identification and discrimination sensitivity of current methods impede the wider adoption of this technology. In this [...] Read more.

Terahertz (THZ) spectroscopy has emerged as a superior label-free sensing technology in the detection, identification, and quantification of biomolecules in various biological samples. However, the limitations in identification and discrimination sensitivity of current methods impede the wider adoption of this technology. In this article, a meticulously designed metasurface is proposed for molecular fingerprint enhancement, consisting of a periodic array of lithium tantalate triangular prism tetramers arranged in a square quartz lattice. The physical mechanism is explained by the finite-difference time-domain (FDTD) method. The metasurface achieves a high quality factor (Q-factor) of 231 and demonstrates excellent THz sensing capabilities with a figure of merit (FoM) of 609. By varying the incident angle of the THz wave, the molecular fingerprint signal is strengthened, enabling the highly sensitive detection of trace amounts of analyte. Consequently, cinnamoylglycine can be detected with a sensitivity limit as low as

1.23 μ g \cdot {c m}^{- 2}

. This study offers critical insights into the advanced application of THz waves in biomedicine, particularly for the detection of urinary biomarkers in various diseases, including gestational diabetes mellitus (GDM). Full article

(This article belongs to the Special Issue Photonics for Bioapplications: Sensors and Technology)

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12 pages, 2608 KiB

Open AccessArticle

Investigation of Interferences of Wearable Sensors with Plant Growth

by Xiao Xiao, Xinyue Liu, Yanbo Liu, Chengjin Tu, Menglong Qu, Jingjing Kong, Yongnian Zhang and Cheng Zhang

Biosensors 2024, 14(9), 439; https://doi.org/10.3390/bios14090439 - 11 Sep 2024

Abstract

Plant wearable sensors have shown exceptional promise in continuously monitoring plant health. However, the potential adverse effects of these sensors on plant growth remain unclear. This study systematically quantifies wearable sensors’ interference with plant growth using two ornamental species, Peperomia tetraphylla and Epipremnum [...] Read more.

Plant wearable sensors have shown exceptional promise in continuously monitoring plant health. However, the potential adverse effects of these sensors on plant growth remain unclear. This study systematically quantifies wearable sensors’ interference with plant growth using two ornamental species, Peperomia tetraphylla and Epipremnum aureum. We evaluated the impacts of four common disturbances—mechanical pressure, hindrance of gas exchange, hindrance of light acquisition, and mechanical constraint—on leaf growth. Our results indicated that the combination of light hindrance and mechanical constraint demonstrated the most significant interference. When the sensor weight was no greater than 0.6 g and the coverage was no greater than 5% of the leaf area, these four disturbances resulted in slight impacts on leaf growth. Additionally, we fabricated a minimally interfering wearable sensor capable of measuring the air temperature of the microclimate of the plant while maintaining plant growth. This research provides valuable insights into optimizing plant wearable sensors, balancing functionality with minimal plant interference. Full article

(This article belongs to the Special Issue Wearable Sensors for Plant Health Monitoring)

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16 pages, 14127 KiB

Open AccessArticle

2PP-Hydrogel Covered Electrodes to Compensate for Media Effects in the Determination of Biomass in a Capillary Wave Micro Bioreactor

by Sven Meinen, Steffen Brinkmann, Kevin Viebrock, Bassant Elbardisy, Henning Menzel, Rainer Krull and Andreas Dietzel

Biosensors 2024, 14(9), 438; https://doi.org/10.3390/bios14090438 - 9 Sep 2024

Abstract

Microbioreactors increase information output in biopharmaceutical screening applications because they can be operated in parallel without consuming large quantities of the pharmaceutical formulations being tested. A capillary wave microbioreactor (cwMBR) has recently been reported, allowing cost-efficient parallelization in an array that can be [...] Read more.

Microbioreactors increase information output in biopharmaceutical screening applications because they can be operated in parallel without consuming large quantities of the pharmaceutical formulations being tested. A capillary wave microbioreactor (cwMBR) has recently been reported, allowing cost-efficient parallelization in an array that can be activated for mixing as a whole. Although impedance spectroscopy can directly distinguish between dead and viable cells, the monitoring of cells in suspension within bioreactors is challenging because the signal is influenced by the potentially varying properties of the culture medium. In order to address this challenge, an impedance sensor consisting of two sets of microelectrodes in a cwMBR is presented. Only one set of electrodes was covered by a two-photon cross-linked hydrogel to become insensitive to the influence of cells while remaining sensitive to the culture medium. With this impedance sensor, the biomass of Saccharomyces cerevisiae could be measured in a range from 1 to 20 g L⁻¹. In addition, the sensor can compensate for a change in the conductivity of the suspension of 5 to 15 mS cm⁻¹. Moreover, the two-photon cross-linking of hydroxyethyl starch methacrylate hydrogel, which has been studied in detail, recommends itself for even much broader sensing applications in miniaturized bioreactors and biosensors. Full article

(This article belongs to the Special Issue MEMS Based Biosensors and Its Applications)

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Graphical abstract

18 pages, 6050 KiB

Open AccessArticle

Investigation of a Camera-Based Contactless Pulse Oximeter with Time-Division Multiplex Illumination Applied on Piglets for Neonatological Applications

by René Thull, Sybelle Goedicke-Fritz, Daniel Schmiech, Aly Marnach, Simon Müller, Christina Körbel, Matthias W. Laschke, Erol Tutdibi, Nasenien Nourkami-Tutdibi, Elisabeth Kaiser, Regine Weber, Michael Zemlin and Andreas R. Diewald

Biosensors 2024, 14(9), 437; https://doi.org/10.3390/bios14090437 - 9 Sep 2024

Abstract

(1) Objective: This study aims to lay a foundation for noncontact intensive care monitoring of premature babies. (2) Methods: Arterial oxygen saturation and heart rate were measured using a monochrome camera and time-division multiplex controlled lighting at three different wavelengths (660 nm, 810 [...] Read more.

(1) Objective: This study aims to lay a foundation for noncontact intensive care monitoring of premature babies. (2) Methods: Arterial oxygen saturation and heart rate were measured using a monochrome camera and time-division multiplex controlled lighting at three different wavelengths (660 nm, 810 nm and 940 nm) on a piglet model. (3) Results: Using this camera system and our newly designed algorithm for further analysis, the detection of a heartbeat and the calculation of oxygen saturation were evaluated. In motionless individuals, heartbeat and respiration were separated clearly during light breathing and with only minor intervention. In this case, the mean difference between noncontact and contact saturation measurements was 0.7% (RMSE = 3.8%, MAE = 2.93%). (4) Conclusions: The new sensor was proven effective under ideal animal experimental conditions. The results allow a systematic improvement for the further development of contactless vital sign monitoring systems. The results presented here are a major step towards the development of an incubator with noncontact sensor systems for use in the neonatal intensive care unit. Full article

(This article belongs to the Special Issue Selected Papers from the 4th International Electronic Conference on Biosensors (IECB 2024))

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12 pages, 2070 KiB

Open AccessArticle

Ultrasensitive Electrochemical Biosensor for Rapid Screening of Chemicals with Estrogenic Effect

by Ruixin Li, Jin Li, Xianbo Lu, Fanli Meng and Jiping Chen

Biosensors 2024, 14(9), 436; https://doi.org/10.3390/bios14090436 - 9 Sep 2024

Abstract

Estrogenic chemicals are widely distributed and structurally diverse. They primarily disrupt estrogen-related metabolism in animals or humans by mimicking the agonistic receptor effects of natural estrogens, thereby influencing the transcription of estrogen receptors to regulate their quantity and sensitivity. This disruption of estrogen-related [...] Read more.

Estrogenic chemicals are widely distributed and structurally diverse. They primarily disrupt estrogen-related metabolism in animals or humans by mimicking the agonistic receptor effects of natural estrogens, thereby influencing the transcription of estrogen receptors to regulate their quantity and sensitivity. This disruption of estrogen-related metabolism can lead to estrogen-related effects, posing risks to biological health, emphasizing the urgent need for simple and effective methods to screen compounds with estrogenic effects. Herein, a new electrochemical biological effect biosensor based on human estrogen receptor α (hERα) is developed, which uses hERα as the biorecognition element and employs the electroactive horseradish peroxidase (HRP) labeled 17β-estradiol (E2) multifunctional conjugate HRP-E2 as the signal-boosting element and ligand competition agent. Based on the specific ligand–receptor interaction principle between the target and nuclear receptor, by allowing the test compound to compete with HRP-E2 conjugate for binding to hERα and testing the electrocatalytic signal of the conjugate that fails to bind to the hERα estrogen receptor, rapid screening and quantitative detection of chemical substances with estrogenic effect have been achieved. The biosensor shows a wide linear range of 40 pM to 40 nM with a detection limit of 17 pM (S/N = 3) for E2, and the detection limit is 2 orders of magnitude better than that of the previously reported sensors. The biosensor based on ligand–receptor binding can not only quantitatively analyze the typical estrogen E2, but also evaluate the relative estrogen effect strength of other estrogen compounds, which has good stability and selectivity. This electrochemical sensing platform displays its promising potential for rapid screening and quantitative detection of chemicals with estrogenic effects. Full article

(This article belongs to the Special Issue Electrochemical and Fluorescent Biosensors: Novel Strategies, Methods, and Materials II)

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17 pages, 4247 KiB

Open AccessArticle

Advanced Liver-on-a-Chip Model for Evaluating Drug Metabolism and Hepatotoxicity

by Sonia Frojdenfal and Agnieszka Zuchowska

Biosensors 2024, 14(9), 435; https://doi.org/10.3390/bios14090435 - 6 Sep 2024

Abstract

The liver has many important functions, including the biotransformation of drugs and detoxification of the human organism. As such, it is also exposed to many harmful substances, which leads to disorders and diseases such as cirrhosis. For these reasons, it seems important to [...] Read more.

The liver has many important functions, including the biotransformation of drugs and detoxification of the human organism. As such, it is also exposed to many harmful substances, which leads to disorders and diseases such as cirrhosis. For these reasons, it seems important to consider liver metabolism and the direct effects on the liver when evaluating the efficacy of new drugs. Accordingly, we have developed an advanced in vitro liver model using an organ-on-a-chip approach that replicates many of the morphological and functional features of the liver in vivo. The model we created can metabolize drugs, which we demonstrated using two widely used anticancer drugs, 5-fluorouracil (5FU) and capecitabine (CAP). In addition, to the best of our knowledge, we are the first who evaluate the direct effects of these drugs not only on the viability of liver model-building cells but on their functions, such as cytochrome P450 activity and albumin production. Our study brings new hope to properly evaluating drug efficacy at the in vitro level. Full article

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

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33 pages, 10567 KiB

Open AccessArticle

Microwave Technique for Linear Skull Fracture Detection—Simulation and Experimental Study Using Realistic Human Head Models

by Mariella Särestöniemi, Daljeet Singh, Mikael von und zu Fraunberg and Teemu Myllylä

Biosensors 2024, 14(9), 434; https://doi.org/10.3390/bios14090434 - 6 Sep 2024

Abstract

Microwave (MW) sensing is regarded as a promising technique for various medical monitoring and diagnostic applications due to its numerous advantages and the potential to be developed into a portable device for use outside hospital settings. The detection of skull fractures and the [...] Read more.

Microwave (MW) sensing is regarded as a promising technique for various medical monitoring and diagnostic applications due to its numerous advantages and the potential to be developed into a portable device for use outside hospital settings. The detection of skull fractures and the monitoring of their healing process would greatly benefit from a rapidly and frequently usable application that can be employed outside the hospital. This paper presents a simulation- and experiment-based study on skull fracture detection with the MW technique using realistic models for the first time. It also presents assessments on the most promising frequency ranges for skull fracture detection within the Industrial, Scientific and Medical (ISM) and ultrawideband (UWB) ranges. Evaluations are carried out with electromagnetic simulations using different head tissue layer models corresponding to different locations in the human head, as well as an anatomically realistic human head simulation model. The measurements are conducted with a real human skull combined with tissue phantoms developed in our laboratory. The comprehensive evaluations show that fractures cause clear differences in antenna and channel parameters (S11 and S21). The difference in S11 is 0.1–20 dB and in S21 is 0.1–30 dB, depending on the fracture width and location. Skull fractures with a less than 1 mm width can be detected with microwaves at different fracture locations. The detectability is frequency dependent. Power flow representations illustrate how fractures impact on the signal propagation at different frequencies. MW-based detection of skull fractures provides the possibility to (1) detect fractures using a safe and low-cost portable device, (2) monitor the healing-process of fractures, and (3) bring essential information for emerging portable MW-based diagnostic applications that can detect, e.g., strokes. Full article

(This article belongs to the Special Issue Medical Imaging and Biosensing)

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14 pages, 7836 KiB

Open AccessReview

Recent Progress in the Synthesis of 3D Complex Plasmonic Intragap Nanostructures and Their Applications in Surface-Enhanced Raman Scattering

by Li Ma, Keyi Zhou, Xinyue Wang, Jiayue Wang, Ruyu Zhao, Yifei Zhang and Fang Cheng

Biosensors 2024, 14(9), 433; https://doi.org/10.3390/bios14090433 - 6 Sep 2024

Abstract

Plasmonic intragap nanostructures (PINs) have garnered intensive attention in Raman-related analysis due to their exceptional ability to enhance light–matter interactions. Although diverse synthetic strategies have been employed to create these nanostructures, the emphasis has largely been on PINs with simple configurations, which often [...] Read more.

Plasmonic intragap nanostructures (PINs) have garnered intensive attention in Raman-related analysis due to their exceptional ability to enhance light–matter interactions. Although diverse synthetic strategies have been employed to create these nanostructures, the emphasis has largely been on PINs with simple configurations, which often fall short in achieving effective near-field focusing. Three-dimensional (3D) complex PINs, distinguished by their intricate networks of internal gaps and voids, are emerging as superior structures for effective light trapping. These structures facilitate the generation of hot spots and hot zones that are essential for enhanced near-field focusing. Nevertheless, the synthesis techniques for these complex structures and their specific impacts on near-field focusing are not well-documented. This review discusses the recent advancements in the synthesis of 3D complex PINs and their applications in surface-enhanced Raman scattering (SERS). We begin by describing the foundational methods for fabricating simple PINs, followed by a discussion on the rational design strategies aimed at developing 3D complex PINs with superior near-field focusing capabilities. We also evaluate the SERS performance of various 3D complex PINs, emphasizing their advanced sensing capabilities. Lastly, we explore the future perspective of 3D complex PINs in SERS applications. Full article

(This article belongs to the Special Issue Functional Nanomaterials for Biosensing (Volume II))

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13 pages, 4393 KiB

Open AccessArticle

A Cost-Effective and Easy-to-Fabricate Conductive Velcro Dry Electrode for Durable and High-Performance Biopotential Acquisition

by Jun Guo, Xuanqi Wang, Ruiyu Bai, Zimo Zhang, Huazhen Chen, Kai Xue, Chuang Ma, Dawei Zang, Erwei Yin, Kunpeng Gao and Bowen Ji

Biosensors 2024, 14(9), 432; https://doi.org/10.3390/bios14090432 - 6 Sep 2024

Abstract

Compared with the traditional gel electrode, the dry electrode is being taken more seriously in bioelectrical recording because of its easy preparation, long-lasting ability, and reusability. However, the commonly used dry AgCl electrodes and silver cloth electrodes are generally hard to record through [...] Read more.

Compared with the traditional gel electrode, the dry electrode is being taken more seriously in bioelectrical recording because of its easy preparation, long-lasting ability, and reusability. However, the commonly used dry AgCl electrodes and silver cloth electrodes are generally hard to record through hair due to their flat contact surface. Claw electrodes can contact skin through hair on the head and body, but the internal claw structure is relatively hard and causes discomfort after being worn for a few hours. Here, we report a conductive Velcro electrode (CVE) with an elastic hook hair structure, which can collect biopotential through body hair. The elastic hooks greatly reduce discomfort after long-time wearing and can even be worn all day. The CVE electrode is fabricated by one-step immersion in conductive silver paste based on the cost-effective commercial Velcro, forming a uniform and durable conductive coating on a cluster of hook microstructures. The electrode shows excellent properties, including low impedance (15.88 kΩ @ 10 Hz), high signal-to-noise ratio (16.0 dB), strong water resistance, and mechanical resistance. After washing in laundry detergent, the impedance of CVE is still 16% lower than the commercial AgCl electrodes. To verify the mechanical strength and recovery capability, we conducted cyclic compression experiments. The results show that the displacement change of the electrode hook hair after 50 compression cycles was still less than 1%. This electrode provides a universal acquisition scheme, including effective acquisition of different parts of the body with or without hair. Finally, the gesture recognition from electromyography (EMG) by the CVE electrode was applied with accuracy above 90%. The CVE proposed in this study has great potential and promise in various human–machine interface (HMI) applications that employ surface biopotential signals on the body or head with hair. Full article

(This article belongs to the Special Issue Advances in Flexible Bioelectronics and Intelligent Biosensing Systems)

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14 pages, 2357 KiB

Open AccessArticle

Comparative Analysis of QCM and Electrochemical Aptasensors for SARS-CoV-2 Detection

by Katarína Nemčeková, Jana Korčeková, Veronika Svitková, Denis Baraniak, Michaela Domšicová, Eva Melníková, Michaela Hornychová, Viktória Szebellaiová, Miroslav Gál and Alexandra Poturnayová

Biosensors 2024, 14(9), 431; https://doi.org/10.3390/bios14090431 - 6 Sep 2024

Abstract

The rapid and accurate detection of SARS-CoV-2, particularly its spike receptor-binding domain (S-RBD), was crucial for managing the COVID-19 pandemic. This study presents the development and optimization of two types of aptasensors: quartz crystal microbalance (QCM) and electrochemical sensors, both employing thiol-modified DNA [...] Read more.

The rapid and accurate detection of SARS-CoV-2, particularly its spike receptor-binding domain (S-RBD), was crucial for managing the COVID-19 pandemic. This study presents the development and optimization of two types of aptasensors: quartz crystal microbalance (QCM) and electrochemical sensors, both employing thiol-modified DNA aptamers for S-RBD detection. The QCM aptasensor demonstrated exceptional sensitivity, achieved by optimizing aptamer concentration, buffer composition, and pre-treatment conditions, with a limit of detection (LOD) of 0.07 pg/mL and a linear range from 1 pg/mL to 0.1 µg/mL, and a significant frequency change was observed upon target binding. The electrochemical aptasensor, designed for rapid and efficient preparation, utilized a one-step modification process that reduced the preparation time to 2 h while maintaining high sensitivity and specificity. Electrochemical impedance spectroscopy (EIS) enabled the detection of S-RBD concentrations as low as 132 ng/mL. Both sensors exhibited high specificity, with negligible non-specific interactions observed in the presence of competing proteins. Additionally, the QCM aptasensor’s functionality and stability were verified in biological fluids, indicating its potential for real-world applications. This study highlights the comparative advantages of QCM and electrochemical aptasensors in terms of preparation time, sensitivity, and specificity, offering valuable insights for the development of rapid, sensitive, and specific diagnostic tools for the detection of SARS-CoV-2 and other viruses. Full article

(This article belongs to the Special Issue Aptamer-Based Biosensing and Bioassays)

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19 pages, 20339 KiB

Open AccessArticle

Enhancing Colorimetric Detection of Nucleic Acids on Nitrocellulose Membranes: Cutting-Edge Applications in Diagnostics and Forensics

by Nidhi Subhashini, Yannick Kerler, Marcus M. Menger, Olga Böhm, Judith Witte, Christian Stadler and Alexander Griberman

Biosensors 2024, 14(9), 430; https://doi.org/10.3390/bios14090430 - 5 Sep 2024

Abstract

This study re-introduces a protein-free rapid test method for nucleic acids on paper based lateral flow assays utilizing special multichannel nitrocellulose membranes and DNA-Gold conjugates, achieving significantly enhanced sensitivity, easier protocols, reduced time of detection, reduced costs of production and advanced multiplexing possibilities. [...] Read more.

This study re-introduces a protein-free rapid test method for nucleic acids on paper based lateral flow assays utilizing special multichannel nitrocellulose membranes and DNA-Gold conjugates, achieving significantly enhanced sensitivity, easier protocols, reduced time of detection, reduced costs of production and advanced multiplexing possibilities. A protein-free nucleic acid-based lateral flow assay (NALFA) with a limit of detection of 1 pmol of DNA is shown for the first time. The total production duration of such an assay was successfully reduced from the currently known several days to just a few hours. The simplification and acceleration of the protocol make the method more accessible and practical for various applications. The developed method supports multiplexing, enabling the simultaneous detection of up to six DNA targets. This multiplexing capability is a significant improvement over traditional line tests and offers more comprehensive diagnostic potential in a single assay. The approach significantly reduces the run time compared to traditional line tests, which enhances the efficiency of diagnostic procedures. The protein-free aspect of this assay minimizes the prevalent complications of cross-reactivity in immunoassays especially in cases of multiplexing. It is also demonstrated that the NALFA developed in this study is amplification-free and hence does not rely on specialized technicians, nor does it involve labour-intensive steps like DNA extraction and PCR processes. Overall, this study presents a robust, efficient, and highly sensitive platform for DNA or RNA detection, addressing several limitations of current methods documented in the literature. The advancements in sensitivity, cost reduction, production time, and multiplexing capabilities mark a substantial improvement, holding great potential for various applications in diagnostics, forensics, and molecular biology. Full article

(This article belongs to the Section Biosensors and Healthcare)

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