Biosensors

Open AccessArticle

Immuno-Sensing at Ultra-Low Concentration of TG2 Protein by Organic Electrochemical Transistors

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Valentina Preziosi

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Mario Barra

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Valeria Rachela Villella

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Biosensors 2023, 13(4), 448; https://doi.org/10.3390/bios13040448 (registering DOI) - 31 Mar 2023

Abstract

Transglutaminase 2 (TG2) is a ubiquitously expressed member of the transglutaminase family with Ca2+-dependent protein crosslinking activity. Its subcellular localization is crucial in determining its function, and indeed, TG2 is found in the extracellular matrix, mitochondria, recycling endosomes, plasma membrane, cytosol, and nucleus [...] Read more.

Transglutaminase 2 (TG2) is a ubiquitously expressed member of the transglutaminase family with Ca2+-dependent protein crosslinking activity. Its subcellular localization is crucial in determining its function, and indeed, TG2 is found in the extracellular matrix, mitochondria, recycling endosomes, plasma membrane, cytosol, and nucleus because it is associated with cell growth, differentiation, and apoptosis. It is involved in several pathologies, such as celiac disease, cardiovascular, hepatic, renal, and fibrosis diseases, carrying out opposite functions of up and down regulation in the progression of the same pathology. Therefore, this fine regulation requires a very sensitive and specific method of identification of TG2, which is to be detected in very small quantities in a deregulated condition. Here, we demonstrate the possibility of detecting TG2 down to attomolar concentration by using organic electrochemical transistors driven by gold electrodes functionalized with anti-TG2 antibodies. In particular, a direct correlation between the TG2 concentration and the transistor transconductance values, as extracted from typical transfer curves, was found. Overall, our findings highlight the potentialities of this new biosensing approach for the detection of TG2 in the context of pathological diseases, offering a rapid and cost-effective alternative to traditional methods. Full article

(This article belongs to the Special Issue Biosensors for Determination of Protein Biomarkers)

Open AccessCommunication

Coumarin-Based Fluorescence Probe for Differentiated Detection of Biothiols and Its Bioimaging in Cells

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Biosensors 2023, 13(4), 447; https://doi.org/10.3390/bios13040447 - 31 Mar 2023

Abstract

In this work, a coumarin derivative, SWJT-14, was synthesized as a fluorescence probe to distinguish cysteine (Cys), homocysteine (Hcy) and glutathione (GSH) in aqueous solutions. The detection limit of Cys, Hcy and GSH for the probe was 0.02 μM, 0.42 μM and [...] Read more.

In this work, a coumarin derivative, SWJT-14, was synthesized as a fluorescence probe to distinguish cysteine (Cys), homocysteine (Hcy) and glutathione (GSH) in aqueous solutions. The detection limit of Cys, Hcy and GSH for the probe was 0.02 μM, 0.42 μM and 0.92 μM, respectively, which was lower than biothiols in cells. The probe reacted with biothiols to generate different products with different conjugated structures. Additionally, it could distinguish Cys, Hcy and GSH using fluorescence and UV-Vis spectra. The detection mechanism was confirmed by MS. SWJT-14 was successfully used in cellular experiments and detected both endogenous and exogenous biothiols. Full article

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

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Open AccessArticle

Craft-and-Stick Xurographic Manufacturing of Integrated Microfluidic Electrochemical Sensing Platform

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Proespichaya Kanatharana

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Panote Thavarungkul

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Wing Cheung Mak

Biosensors 2023, 13(4), 446; https://doi.org/10.3390/bios13040446 - 31 Mar 2023

Abstract

An innovative modular approach for facile design and construction of flexible microfluidic biosensor platforms based on a dry manufacturing “craft-and-stick” approach is developed. The design and fabrication of the flexible graphene paper electrode (GPE) unit and polyethylene tetraphthalate sheet (PET)6/adhesive fluidic unit are [...] Read more.

An innovative modular approach for facile design and construction of flexible microfluidic biosensor platforms based on a dry manufacturing “craft-and-stick” approach is developed. The design and fabrication of the flexible graphene paper electrode (GPE) unit and polyethylene tetraphthalate sheet (PET)6/adhesive fluidic unit are completed by an economic and generic xurographic craft approach. The GPE widths and the microfluidic channels can be constructed down to 300 μm and 200 μm, respectively. Both units were assembled by simple double-sided adhesive tapes into a microfluidic integrated GPE (MF-iGPE) that are flexible, thin (<0.5 mm), and lightweight (0.4 g). We further functionalized the iGPE with Prussian blue and glucose oxidase for the fabrication of MF-iGPE glucose biosensors. With a closed-channel PET fluidic pattern, the MF-iGPE glucose biosensors were packaged and sealed to protect the integrated device from moisture for storage and could easily open with scissors for sample loading. Our glucose biosensors showed 2 linear dynamic regions of 0.05–1.0 and 1.0–5.5 mmol L⁻¹ glucose. The MF-iGPE showed good reproducibility for glucose detection (RSD < 6.1%, n = 6) and required only 10 μL of the analyte. This modular craft-and-stick manufacturing approach could potentially further develop along the concept of paper-crafted model assembly kits suitable for low-resource laboratories or classroom settings. Full article

(This article belongs to the Special Issue Feature Issue of Nano- and Micro-Technologies in Biosensors Section)

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Open AccessArticle

Obtaining of ZnO/Fe₂O₃ Thin Nanostructured Films by AACVD for Detection of Ppb-Concentrations of NO₂ as a Biomarker of Lung Infections

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Artem S. Mokrushin

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Yulia M. Gorban

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Aleksey A. Averin

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Philipp Yu. Gorobtsov

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Nikolay P. Simonenko

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Yury Yu. Lebedinskii

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Elizaveta P. Simonenko

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Nikolay T. Kuznetsov

Biosensors 2023, 13(4), 445; https://doi.org/10.3390/bios13040445 - 31 Mar 2023

Abstract

ZnO/Fe₂O₃ nanocomposites with different concentration and thickness of the Fe₂O₃ layer were obtained by two-stage aerosol vapor deposition (AACVD). It was shown that the ZnO particles have a wurtzite structure with an average size of 51–66 nm, [...] Read more.

ZnO/Fe₂O₃ nanocomposites with different concentration and thickness of the Fe₂O₃ layer were obtained by two-stage aerosol vapor deposition (AACVD). It was shown that the ZnO particles have a wurtzite structure with an average size of 51–66 nm, and the iron oxide particles on the ZnO surface have a hematite structure and an average size of 23–28 nm. According to EDX data, the iron content in the films was found to be 1.3–5.8 at.%. The optical properties of the obtained films were studied, and the optical band gap was found to be 3.16–3.26 eV. Gas-sensitive properties at 150–300 °C were studied using a wide group of analyte gases: CO, NH₃, H₂, CH₄, C₆H₆, ethanol, acetone, and NO₂. A high response to 100 ppm acetone and ethanol at 225–300 °C and a high and selective response to 300–2000 ppb NO₂ at 175 °C were established. The effect of humidity on the magnitude and shape of the signal obtained upon NO₂ detection was studied. Full article

(This article belongs to the Special Issue Smart Materials for Chemical and Biosensing)

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Open AccessArticle

Advanced Urea Precursors Driven NiCo₂O₄ Nanostructures Based Non-Enzymatic Urea Sensor for Milk and Urine Real Sample Applications

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Zafar Hussain Ibupoto

Biosensors 2023, 13(4), 444; https://doi.org/10.3390/bios13040444 - 31 Mar 2023

Abstract

The electrochemical performance of NiCo₂O₄ with urea precursors was evaluated in order to develop a non-enzymatic urea sensor. In this study, NiCo₂O₄ nanostructures were synthesized hydrothermally at different concentrations of urea and characterized using scanning electron microscopy [...] Read more.

The electrochemical performance of NiCo₂O₄ with urea precursors was evaluated in order to develop a non-enzymatic urea sensor. In this study, NiCo₂O₄ nanostructures were synthesized hydrothermally at different concentrations of urea and characterized using scanning electron microscopy and X-ray diffraction. Nanostructures of NiCo₂O₄ exhibit a nanorod-like morphology and a cubic phase crystal structure. Urea can be detected with high sensitivity through NiCo₂O₄ nanostructures driven by urea precursors under alkaline conditions. A low limit of detection of 0.05 and an analytical range of 0.1 mM to 10 mM urea are provided. The concentration of 006 mM was determined by cyclic voltammetry. Chronoamperometry was used to determine the linear range in the range of 0.1 mM to 8 mM. Several analytical parameters were assessed, including selectivity, stability, and repeatability. NiCo₂O₄ nanostructures can also be used to detect urea in various biological samples in a practical manner. Full article

(This article belongs to the Special Issue Nanomaterials for Biosensors)

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Open AccessEditorial

New and Improved Nanomaterials and Approaches for Optical Bio- and Immunosensors

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Boris B. Dzantiev

Biosensors 2023, 13(4), 443; https://doi.org/10.3390/bios13040443 - 31 Mar 2023

Abstract

The current state in the development of biosensors is largely associated with the search for new approaches to simplify measurements and lower detection limits [...] Full article

(This article belongs to the Special Issue New and Improved Nanomaterials and Approaches for Optical Bio- and Immunosensors)

Open AccessArticle

Viscoelastic Properties of Zona Pellucida of Oocytes Characterized by Transient Electrical Impedance Spectroscopy

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Biosensors 2023, 13(4), 442; https://doi.org/10.3390/bios13040442 - 30 Mar 2023

Abstract

The success rate in vitro fertilization is significantly linked to the quality of the oocytes. The oocyte’s membrane is encapsulated by a shell of gelatinous extracellular matrix, called zona pellucida, which undergoes dynamic changes throughout the reproduction cycle. During the window of highest [...] Read more.

The success rate in vitro fertilization is significantly linked to the quality of the oocytes. The oocyte’s membrane is encapsulated by a shell of gelatinous extracellular matrix, called zona pellucida, which undergoes dynamic changes throughout the reproduction cycle. During the window of highest fertility, the zona pellucida exhibits a softening phase, while it remains rigid during oocyte maturation and again after fertilization. These variations in mechanical properties facilitate or inhibit sperm penetration. Since successful fertilization considerably depends on the state of the zona pellucida, monitoring of the hardening process of the zona pellucida is vital. In this study, we scrutinized two distinct genetic mouse models, namely, fetuin-B wild-type and fetuin-B/ovastacin double deficient with normal and super-soft zona pellucida, respectively. We evaluated the hardening with the help of a microfluidic aspiration-assisted electrical impedance spectroscopy system. An oocyte was trapped by a microhole connected to a microfluidic channel by applying suction pressure. Transient electrical impedance spectra were taken by microelectrodes surrounding the microhole. The time-depending recovery of zona pellucida deflections to equilibrium was used to calculate the Young’s modulus and, for the first time, absolute viscosity values. The values were obtained by fitting the curves with an equivalent mechanical circuit consisting of a network of dashpots and springs. The observer-independent electrical readout in combination with a fitting algorithm for the calculation of the viscoelastic properties demonstrates a step toward a more user-friendly and easy-to-use tool for the characterizing and better understanding of the rheological properties of oocytes. Full article

(This article belongs to the Special Issue Impedance-Spectroscopy-Based Biosensors)

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Open AccessFeature PaperArticle

A Direct Catalytic Ethanol Fuel Cell (DCEFC) Modified by LDHs, or by Catalase-LDHs, and Improvement in Its Kinetic Performance: Applications for Human Saliva and Disinfectant Products for COVID-19

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Biosensors 2023, 13(4), 441; https://doi.org/10.3390/bios13040441 - 30 Mar 2023

Abstract

In this work, it has been experimentally proven that the kinetic performance of a common Direct Catalytic Ethanol Fuel Cell (DCEFC) can be increased by introducing nanostructured (Zn^II,Al^III(OH)₂)⁺NO₃⁻·H₂O Layered Double [...] Read more.

In this work, it has been experimentally proven that the kinetic performance of a common Direct Catalytic Ethanol Fuel Cell (DCEFC) can be increased by introducing nanostructured (Zn^II,Al^III(OH)₂)⁺NO₃⁻·H₂O Layered Double Hydroxides (LDHs) into the anode compartment. Carrying out the measurements with the open-circuit voltage method and using a kinetic format, it has been shown that the introduction of LDHs in the anodic compartment implies a 1.3-fold increase in the calibration sensitivity of the method. This improvement becomes even greater in the presence of hydrogen peroxide in a solution. Furthermore, we show that the calibration sensitivity increased by 8-times, when the fuel cell is modified by the enzyme catalase, crosslinked on LDHs and in the presence of hydrogen peroxide. The fuel cell, thus modified (with or without enzyme), has been used for analytical applications on real samples, such as biological (human saliva) and hand disinfectant samples, commonly used for the prevention of COVID-19, obtaining very positive results from both analytical and kinetic points of view on ethanol detection. Moreover, if the increase in the calibration sensitivity is of great importance from the point of view of analytical applications, it must be remarked that the increase in the speed of the ethanol oxidation process in the fuel cell can also be extremely useful for the purposes of improving the energy performance of a DCEFC. Full article

(This article belongs to the Special Issue New Biosensors and Nanosensors)

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Open AccessArticle

Bioimpedance-Measurement-Based Non-Invasive Method for In Ovo Chicken Egg Sexing

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Congo Tak Shing Ching

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Biosensors 2023, 13(4), 440; https://doi.org/10.3390/bios13040440 - 30 Mar 2023

Abstract

Day-old male chick culling is one of the world’s most inhumane problems in the poultry industry. Every year, seven billion male chicks are slaughtered in laying-hen hatcheries due to their higher feed exchange rate, lower management than female chicks, and higher production costs. [...] Read more.

Day-old male chick culling is one of the world’s most inhumane problems in the poultry industry. Every year, seven billion male chicks are slaughtered in laying-hen hatcheries due to their higher feed exchange rate, lower management than female chicks, and higher production costs. This study describes a novel non-invasive method for determining the gender of chicken eggs. During the incubation period of fourteen days, four electrodes were attached to each egg for data collection. On the last day of incubation, a standard polymerase chain reaction (PCR)-based chicken gender determination protocol was applied to the eggs to obtain the gender information. A relationship was built between the collected data and the egg’s gender, and it was discovered to have a reliable connection, indicating that the chicken egg gender can be determined by measuring the impedance data of the eggs on day 9 of incubation with the four electrodes set and using the self-normalization technique. This is a groundbreaking discovery, demonstrating that impedance spectroscopy can be used to sex chicken eggs before they hatch, relieving the poultry industry of such an ethical burden. Full article

(This article belongs to the Special Issue Field and Remote Sensors for Environmental Health and Food Safety Diagnostics)

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Open AccessReview

Optical Detection of Cancer Cells Using Lab-on-a-Chip

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Luis Abraham García-Hernández

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Eduardo Martínez-Martínez

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Denni Pazos-Solís

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Javier Aguado-Preciado

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Ateet Dutt

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Abraham Ulises Chávez-Ramírez

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Brian Korgel

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Ashutosh Sharma

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Goldie Oza

Biosensors 2023, 13(4), 439; https://doi.org/10.3390/bios13040439 - 30 Mar 2023

Abstract

The global need for accurate and efficient cancer cell detection in biomedicine and clinical diagnosis has driven extensive research and technological development in the field. Precision, high-throughput, non-invasive separation, detection, and classification of individual cells are critical requirements for successful technology. Lab-on-a-chip devices [...] Read more.

The global need for accurate and efficient cancer cell detection in biomedicine and clinical diagnosis has driven extensive research and technological development in the field. Precision, high-throughput, non-invasive separation, detection, and classification of individual cells are critical requirements for successful technology. Lab-on-a-chip devices offer enormous potential for solving biological and medical problems and have become a priority research area for microanalysis and manipulating cells. This paper reviews recent developments in the detection of cancer cells using the microfluidics-based lab-on-a-chip method, focusing on describing and explaining techniques that use optical phenomena and a plethora of probes for sensing, amplification, and immobilization. The paper describes how optics are applied in each experimental method, highlighting their advantages and disadvantages. The discussion includes a summary of current challenges and prospects for cancer diagnosis. Full article

(This article belongs to the Special Issue Microfluidic Systems for Diagnosing Cancer and Infectious Diseases)

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Open AccessEditorial

Special Issue “Women in Science”—The First Edition

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Cecilia Cristea

Biosensors 2023, 13(4), 438; https://doi.org/10.3390/bios13040438 - 30 Mar 2023

Abstract

This Special Issue entitled “Women in Biosensors” has been launched to celebrate and highlight the achievements of women in the biosensors research area, presenting biosensor-related work performed in groups leaded by women scientists [...] Full article

(This article belongs to the Special Issue Women in Biosensors)

Open AccessArticle

Kinetic Determination of Acetylsalicylic Acid Using a CdTe/AgInS₂ Photoluminescence Probe and Different Chemometric Models

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Rafael C. Castro

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Ricardo N. M. J. Páscoa

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M. Lúcia M. F. S. Saraiva

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João L. M. Santos

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David S. M. Ribeiro

Biosensors 2023, 13(4), 437; https://doi.org/10.3390/bios13040437 - 30 Mar 2023

Abstract

The combination of multiple quantum dots (QDs) in a multi-emitter nanoprobe can be envisaged as a promising sensing scheme, as it enables obtaining a collective response of individual emitters towards a given analyte and allows for achieving specific analyte-response profiles. The processing of [...] Read more.

The combination of multiple quantum dots (QDs) in a multi-emitter nanoprobe can be envisaged as a promising sensing scheme, as it enables obtaining a collective response of individual emitters towards a given analyte and allows for achieving specific analyte-response profiles. The processing of these profiles using adequate chemometric methods empowers a more sensitive, reliable and selective determination of the target analyte. In this work, we developed a kinetic fluorometric method consisting of a dual CdTe/AgInS₂ quantum dots photoluminescence probe for the determination of acetylsalicylic acid (ASA). The fluorometric response was acquired as second-order time-based excitation/emission matrices that were subsequently processed using chemometric methods seeking to assure the second-order advantage. The data obtained in this work are considered second-order data as they have a three-dimensional size, I × J × K (where I represents the samples’ number, J the fluorescence emission wavelength while K represents the time). In order to select the most adequate chemometric method regarding the obtained data structure, different chemometric models were tested, namely unfolded partial least squares (U-PLS), N-way partial least squares (N-PLS), multilayer feed-forward neural networks (MLF-NNs) and radial basis function neural networks (RBF-NNs). Full article

(This article belongs to the Special Issue Electrochemiluminescence Biosensors for Imaging or Detection of Biomarkers, Virus, Bacteria, and Metal Ions)

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Open AccessEditorial

Microfluidic Based Organ-on-Chips and Biomedical Application

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Qiushi Li

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Zhaoduo Tong

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Hongju Mao

Biosensors 2023, 13(4), 436; https://doi.org/10.3390/bios13040436 - 29 Mar 2023

Abstract

Organ-on-a-Chip is a microfluidic cell culture device manufactured via microchip fabrication methods [...] Full article

(This article belongs to the Special Issue Microfluidic Based Organ-on-Chips and Biomedical Application)

Open AccessReview

Luminescent Guests Encapsulated in Metal–Organic Frameworks for Portable Fluorescence Sensor and Visual Detection Applications: A Review

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Biosensors 2023, 13(4), 435; https://doi.org/10.3390/bios13040435 - 29 Mar 2023

Abstract

Metal–organic frameworks (MOFs) have excellent applicability in several fields and have significant structural advantages, due to their open pore structure, high porosity, large specific surface area, and easily modifiable and functionalized porous surface. In addition, a variety of luminescent guest (LG) species can [...] Read more.

Metal–organic frameworks (MOFs) have excellent applicability in several fields and have significant structural advantages, due to their open pore structure, high porosity, large specific surface area, and easily modifiable and functionalized porous surface. In addition, a variety of luminescent guest (LG) species can be encapsulated in the pores of MOFs, giving MOFs a broader luminescent capability. The applications of a variety of LG@MOF sensors, constructed by doping MOFs with LGs such as lanthanide ions, carbon quantum dots, luminescent complexes, organic dyes, and metal nanoclusters, for fluorescence detection of various target analyses such as ions, biomarkers, pesticides, and preservatives are systematically introduced in this review. The development of these sensors for portable visual fluorescence sensing applications is then covered. Finally, the challenges that these sectors currently face, as well as the potential for future growth, are briefly discussed. Full article

(This article belongs to the Special Issue Advances in Fluorescent Probe Biosensing)

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Open AccessArticle

Surfactant-Assisted Label-Free Fluorescent Aptamer Biosensors and Binding Assays

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Hanxiao Zhang

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Albert Zehan Li

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Juewen Liu

Biosensors 2023, 13(4), 434; https://doi.org/10.3390/bios13040434 - 29 Mar 2023

Abstract

Using DNA staining dyes such as SYBR Green I (SGI) and thioflavin T (ThT) to perform label-free detection of aptamer binding has been performed for a long time for both binding assays and biosensor development. Since these dyes are cationic, they can also [...] Read more.

Using DNA staining dyes such as SYBR Green I (SGI) and thioflavin T (ThT) to perform label-free detection of aptamer binding has been performed for a long time for both binding assays and biosensor development. Since these dyes are cationic, they can also adsorb to the wall of reaction vessels leading to unstable signals and even false interpretations of the results. In this work, the stability of the signal was first evaluated using ThT and the classic adenosine aptamer. In a polystyrene microplate, a drop in fluorescence was observed even when non-binding targets or water were added, whereas a more stable signal was achieved in a quartz cuvette. Equilibrating the system can also improve signal stability. In addition, a few polymers and surfactants were also screened, and 0.01% Triton X-100 was found to have the best protection effect against fluorescence signal decrease due to dye adsorption. Three aptamers for Hg²⁺, adenosine, and cortisol were tested for their sensitivity and signal stability in the absence and presence of Triton X-100. In each case, the sensitivity was similar, whereas the signal stability was better for the surfactant. This study indicates that careful control experiments need to be designed to ensure reliable results and that the reliability can be improved by using Triton X-100 and a long equilibration time. Full article

(This article belongs to the Special Issue Fluorescent Materials with Excellent Biocompatibility and Their Application in Bio-Sensing, Bio-Imaging)

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Open AccessArticle

Biosensor Design for the Detection of Circulating Tumor Cells Using the Quartz Crystal Resonator Technique

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Raad A. Alawajji

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Zeid A. Nima Alsudani

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Alexandrus S. Biris

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Ganesh K. Kannarpady

Biosensors 2023, 13(4), 433; https://doi.org/10.3390/bios13040433 - 29 Mar 2023

Abstract

A new mass-sensitive biosensing approach for detecting circulating tumor cells (CTCs) using a quartz crystal resonator (QCR) has been developed. A mathematical model was used to design a ring electrode-based QCR to eliminate the Gaussian spatial distribution of frequency response in the first [...] Read more.

A new mass-sensitive biosensing approach for detecting circulating tumor cells (CTCs) using a quartz crystal resonator (QCR) has been developed. A mathematical model was used to design a ring electrode-based QCR to eliminate the Gaussian spatial distribution of frequency response in the first harmonic mode, a characteristic of QCRs, without compromising the sensitivity of frequency response. An ink-dot method was used to validate the ring electrode fabricated based on our model. Furthermore, the ring electrode QCR was experimentally tested for its ability to capture circulating tumor cells, and the results were compared with a commercially available QCR with a keyhole electrode. An indirect method of surface immobilization technique was employed via modification of the SiO₂ surface of the ring electrode using a silane, protein, and anti-EpCAM. The ring electrode successfully demonstrated eliminating the spatial nonuniformity of frequency response for three cancer cell lines, i.e., MCF-7, PANC-1, and PC-3, compared with the keyhole QCR, which showed nonuniform spatial response for the same cancer cell lines. These results are promising for developing QCR-based biosensors for the early detection of cancer cells, with the potential for point-of-care diagnosis for cancer screening. Full article

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

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Open AccessCommunication

Estradiol Detection for Aquaculture Exploiting Plasmonic Spoon-Shaped Biosensors

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Francesco Arcadio

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Mimimorena Seggio

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Luigi Zeni

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Alessandra Maria Bossi

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Nunzio Cennamo

Biosensors 2023, 13(4), 432; https://doi.org/10.3390/bios13040432 - 29 Mar 2023

Abstract

In this work, a surface plasmon resonance (SPR) biosensor based on a spoon-shaped waveguide combined with an estrogen receptor (ERα) was developed and characterized for the detection and the quantification of estradiol in real water samples. The fabrication process for realizing the SPR [...] Read more.

In this work, a surface plasmon resonance (SPR) biosensor based on a spoon-shaped waveguide combined with an estrogen receptor (ERα) was developed and characterized for the detection and the quantification of estradiol in real water samples. The fabrication process for realizing the SPR platform required a single step consisting of metal deposition on the surface of a polystyrene spoon-shaped waveguide featuring a built-in measuring cell. The biosensor was achieved by functionalizing the bowl sensitive surface with a specific estrogen receptor (ERα) that was able to bind the estradiol. In a first phase, the biosensor tests were performed in a phosphate buffer solution obtaining a limit of detection (LOD) equal to 0.1 pM. Then, in order to evaluate the biosensor’s response in different real matrices related to aquaculture, its performances were examined in seawater and freshwater. The experimental results support the possibility of using the ERα-based biosensor for the screening of estradiol in both matrices. Full article

(This article belongs to the Special Issue New Progress in Optical Fiber-Based Biosensors)

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Open AccessArticle

Development of Single-Channel Dual-Element Custom-Made Ultrasound Scanner with Miniature Optical Position Tracker for Freehand Imaging

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Yen-Lung Chen

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Huihua Kenny Chiang

Biosensors 2023, 13(4), 431; https://doi.org/10.3390/bios13040431 - 28 Mar 2023

Abstract

Handheld ultrasound has great potential in resource-limited areas, and can improve healthcare for rural populations. Single-channel ultrasound has been widely used in many clinical ultrasound applications, and optical tracking is considered accurate and reliable. In this study, we developed a 10 MHz lead [...] Read more.

Handheld ultrasound has great potential in resource-limited areas, and can improve healthcare for rural populations. Single-channel ultrasound has been widely used in many clinical ultrasound applications, and optical tracking is considered accurate and reliable. In this study, we developed a 10 MHz lead magnesium niobate–lead titanate (PMN-PT) dual-element ultrasound transducer combined with a miniature optical position tracker, and then measured the rectus femoris of the thigh, upper arm, and cheek muscles. Compared to single-element transducers, dual-element transducers improve the contrast of near-field signals, effectively reduce noise, and are suitable for measuring curved surfaces. The purpose of position tracking is to calculate the location of the ultrasound transducer during the measurement process. By utilizing positioning information, 2D ultrasound imaging can be achieved while maintaining structural integrity. The dual-element ultrasound scanner presented in this study can enable continuous scanning over a large area without a scanning width limitation. The custom-made dual-element ultrasound scanner has the advantage of being a portable, reliable, and low-cost ultrasound device, and is helpful in popularizing medical care for remote villages. Full article

(This article belongs to the Special Issue Ultrasound Imaging and Sensing in Medicine with Innovative Transducers)

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Open AccessArticle

Development of an Enzymatic Biosensor Using Glutamate Oxidase on Organic–Inorganic-Structured, Electrospun Nanofiber-Modified Electrodes for Monosodium Glutamate Detection

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Hamdiye Atilgan

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Betul Unal

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Esra Evrim Yalcinkaya

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Biosensors 2023, 13(4), 430; https://doi.org/10.3390/bios13040430 - 28 Mar 2023

Abstract

Herein, dendrimer-modified montmorillonite (Mt)-decorated poly-Ɛ-caprolactone (PCL) and chitosan (CHIT)-based nanofibers were prepared. Mt was modified with a poly(amidoamine) generation 1 (PAMAM_G1) dendrimer, and the obtained PAMAM_G1–Mt was incorporated into the PCL–CHIT nanofiber’s structure. The PCL–CHIT/PAMAM_G1–Mt nanofibers were [...] Read more.

Herein, dendrimer-modified montmorillonite (Mt)-decorated poly-Ɛ-caprolactone (PCL) and chitosan (CHIT)-based nanofibers were prepared. Mt was modified with a poly(amidoamine) generation 1 (PAMAM_G1) dendrimer, and the obtained PAMAM_G1–Mt was incorporated into the PCL–CHIT nanofiber’s structure. The PCL–CHIT/PAMAM_G1–Mt nanofibers were conjugated with glutamate oxidase (GluOx) to design a bio-based detection system for monosodium glutamate (MSG). PAMAM_G1–Mt was added to the PCL–CHIT backbone to provide a multipoint binding side to immobilize GluOx via covalent bonds. After the characterization of PCL–CHIT/PAMAM_G1–Mt/GluOx, it was calibrated for MSG. The linear ranges were determined from 0.025 to 0.25 mM MSG using PCL–CHIT/Mt/GluOx and from 0.0025 to 0.175 mM MSG using PCL–CHIT/PAMAMG₁–Mt/GluOx (with a detection limit of 7.019 µM for PCL–CHIT/Mt/GluOx and 1.045 µM for PCL–CHIT/PAMAMG₁–Mt/GluOx). Finally, PCL–CHIT/PAMAMG₁–Mt/GluOx was applied to analyze MSG content in tomato soup without interfering with the sample matrix, giving a recovery percentage of 103.125%. Hence, the nanofiber modification with dendrimer-intercalated Mt and GluOx conjugation onto the formed nanocomposite structures was performed, and the PCL–CHIT/PAMAM_G1–Mt/GluOx system was successfully developed for MSG detection. Full article

(This article belongs to the Special Issue Advances in Enzyme-Based Biosensors)

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