Biosensors

17 pages, 5826 KiB

Open AccessArticle

Fluorescent RET-Based Chemosensor Bearing 1,8-Naphthalimide and Styrylpyridine Chromophores for Ratiometric Detection of Hg²⁺ and Its Bio-Application

by Pavel A. Panchenko, Anastasija V. Efremenko, Anna S. Polyakova, Alexey V. Feofanov, Maria A. Ustimova, Yuri V. Fedorov and Olga A. Fedorova

Biosensors 2022, 12(9), 770; https://doi.org/10.3390/bios12090770 - 19 Sep 2022

Cited by 7 | Viewed by 2517

Abstract

Dyad compound NI-SP bearing 1,8-naphthalimide (NI) and styrylpyridine (SP) photoactive units, in which the N-phenylazadithia-15-crown-5 ether receptor is linked with the energy donor naphthalimide chromophore, has been evaluated as a ratiometric fluorescent chemosensor for mercury (II) ions in living cells. In an aqueous [...] Read more.

Dyad compound NI-SP bearing 1,8-naphthalimide (NI) and styrylpyridine (SP) photoactive units, in which the N-phenylazadithia-15-crown-5 ether receptor is linked with the energy donor naphthalimide chromophore, has been evaluated as a ratiometric fluorescent chemosensor for mercury (II) ions in living cells. In an aqueous solution, NI-SP selectively responds to the presence of Hg²⁺ via the enhancement in the emission intensity of NI due to the inhibition of the photoinduced electron transfer from the receptor to the NI fragment. At the same time, the long wavelength fluorescence band of SP, arising as a result of resonance energy transfer from the excited NI unit, appears to be virtually unchanged upon Hg²⁺ binding. This allows self-calibration of the optical response. The observed spectral behavior is consistent with the formation of the (NI-SP)·Hg²⁺ complex (dissociation constant 0.13 ± 0.04 µM). Bio-imaging studies showed that the ratio of fluorescence intensity in the 440–510 nm spectral region to that in the 590–650 nm region increases from 1.1 to 2.8 when cells are exposed to an increasing concentration of mercury (II) ions, thus enabling the detection of intracellular Hg²⁺ ions and their quantitative analysis in the 0.04–1.65 μM concentration range. Full article

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

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13 pages, 2390 KiB

Open AccessArticle

Electrochemical Sensing of Favipiravir with an Innovative Water-Dispersible Molecularly Imprinted Polymer Based on the Bimetallic Metal-Organic Framework: Comparison of Morphological Effects

by Nevin Erk, Mohammad Mehmandoust and Mustafa Soylak

Biosensors 2022, 12(9), 769; https://doi.org/10.3390/bios12090769 - 19 Sep 2022

Cited by 25 | Viewed by 3053

Abstract

Molecularly imprinted polymers (MIPs) are widely used as modifiers in electrochemical sensors due to their high sensitivity and promise of inexpensive mass manufacturing. Here, we propose and demonstrate a novel MIP-sensor that can measure the electrochemical activity of favipiravir (FAV) as an antiviral [...] Read more.

Molecularly imprinted polymers (MIPs) are widely used as modifiers in electrochemical sensors due to their high sensitivity and promise of inexpensive mass manufacturing. Here, we propose and demonstrate a novel MIP-sensor that can measure the electrochemical activity of favipiravir (FAV) as an antiviral drug, thereby enabling quantification of the concentration of FAV in biological and river water samples and in real-time. MOF nanoparticles’ application with various shapes to determine FAV at nanomolar concentrations was described. Two different MOF nanoparticle shapes (dodecahedron and sheets) were systematically compared to evaluate the electrochemical performance of FAV. After carefully examining two different morphologies of MIP-Co-Ni@MOF, the nanosheet form showed a higher performance and efficiency than the nanododecahedron. When MIP-Co/Ni@MOF-based and NIP-Co/Ni@MOF electrodes (nanosheets) were used instead, the minimum target concentrations detected were 7.5 × 10⁻¹¹ (MIP-Co-Ni@MOF) and 8.17 × 10⁻⁹ M (NIP-Co-Ni@MOF), respectively. This is a significant improvement (>10²), which is assigned to the large active surface area and high fraction of surface atoms, increasing the amount of greater analyte adsorption during binding. Therefore, water-dispersible MIP-Co-Ni@MOF nanosheets were successfully applied for trace-level determination of FAV in biological and water samples. Our findings seem to provide useful guidance in the molecularly imprinted polymer design of MOF-based materials to help establish quantitative rules in designing MOF-based sensors for point of care (POC) systems. Full article

(This article belongs to the Special Issue Role of Electrochemical Biosensors within Sustainable Food Chains and Food Safety)

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13 pages, 1817 KiB

Open AccessArticle

Model of the SARS-CoV-2 Virus for Development of a DNA-Modified, Surface-Enhanced Raman Spectroscopy Sensor with a Novel Hybrid Plasmonic Platform in Sandwich Mode

by Mariia V. Samodelova, Olesya O. Kapitanova, Nadezda F. Meshcheryakova, Sergey. M. Novikov, Nikita R. Yarenkov, Oleg A. Streletskii, Dmitry I. Yakubovsky, Fedor I. Grabovenko, Gleb A. Zhdanov, Aleksey V. Arsenin, Valentyn S. Volkov, Elena G. Zavyalova, Irina A. Veselova and Maria I. Zvereva

Biosensors 2022, 12(9), 768; https://doi.org/10.3390/bios12090768 - 19 Sep 2022

Cited by 7 | Viewed by 3092

Abstract

The recent severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) infection has posed a great challenge for the development of ultra-fast methods for virus identification based on sensor principles. We created a structure modeling surface and size of the SARS-CoV-2 virus and used it [...] Read more.

The recent severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) infection has posed a great challenge for the development of ultra-fast methods for virus identification based on sensor principles. We created a structure modeling surface and size of the SARS-CoV-2 virus and used it in comparison with the standard antigen SARS-CoV-2—the receptor-binding domain (RBD) of the S-protein of the envelope of the SARS-CoV-2 virus from the Wuhan strain—for the development of detection of coronaviruses using a DNA-modified, surface-enhanced Raman scattering (SERS)-based aptasensor in sandwich mode: a primary aptamer attached to the plasmonic surface—RBD-covered Ag nanoparticle—the Cy3-labeled secondary aptamer. Fabricated novel hybrid plasmonic structures based on “Ag mirror-SiO₂-nanostructured Ag” demonstrate sensitivity for the detection of investigated analytes due to the combination of localized surface plasmons in nanostructured silver surface and the gap surface plasmons in a thin dielectric layer of SiO₂ between silver layers. A specific SERS signal has been obtained from SERS-active compounds with RBD-specific DNA aptamers that selectively bind to the S protein of synthetic virion (dissociation constants of DNA-aptamer complexes with protein in the range of 10 nM). The purpose of the study is to systematically analyze the combination of components in an aptamer-based sandwich system. A developed virus size simulating silver particles adsorbed on an aptamer-coated sensor provided a signal different from free RBD. The data obtained are consistent with the theory of signal amplification depending on the distance of the active compound from the amplifying surface and the nature of such a compound. The ability to detect the target virus due to specific interaction with such DNA is quantitatively controlled by the degree of the quenching SERS signal from the labeled compound. Developed indicator sandwich-type systems demonstrate high stability. Such a platform does not require special permissions to work with viruses. Therefore, our approach creates the promising basis for fostering the practical application of ultra-fast, amplification-free methods for detecting coronaviruses based on SARS-CoV-2. Full article

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

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32 pages, 4938 KiB

Open AccessReview

Recent Progresses in Development of Biosensors for Thrombin Detection

by Reza Eivazzadeh-Keihan, Zahra Saadatidizaji, Ali Maleki, Miguel de la Guardia, Mohammad Mahdavi, Sajjad Barzegar and Samad Ahadian

Biosensors 2022, 12(9), 767; https://doi.org/10.3390/bios12090767 - 19 Sep 2022

Cited by 21 | Viewed by 3872

Abstract

Thrombin is a serine protease with an essential role in homeostasis and blood coagulation. During vascular injuries, thrombin is generated from prothrombin, a plasma protein, to polymerize fibrinogen molecules into fibrin filaments. Moreover, thrombin is a potent stimulant for platelet activation, which causes [...] Read more.

Thrombin is a serine protease with an essential role in homeostasis and blood coagulation. During vascular injuries, thrombin is generated from prothrombin, a plasma protein, to polymerize fibrinogen molecules into fibrin filaments. Moreover, thrombin is a potent stimulant for platelet activation, which causes blood clots to prevent bleeding. The rapid and sensitive detection of thrombin is important in biological analysis and clinical diagnosis. Hence, various biosensors for thrombin measurement have been developed. Biosensors are devices that produce a quantifiable signal from biological interactions in proportion to the concentration of a target analyte. An aptasensor is a biosensor in which a DNA or RNA aptamer has been used as a biological recognition element and can identify target molecules with a high degree of sensitivity and affinity. Designed biosensors could provide effective methods for the highly selective and specific detection of thrombin. This review has attempted to provide an update of the various biosensors proposed in the literature, which have been designed for thrombin detection. According to their various transducers, the constructions and compositions, the performance, benefits, and restrictions of each are summarized and compared. Full article

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

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16 pages, 6639 KiB

Open AccessArticle

Development of an Open Microfluidic Platform for Oocyte One-Stop Vitrification with Cryotop Method

by Shu Miao, Chenxi Guo, Ze Jiang, Hao-Xiang Wei, Xin Jiang, Jingkai Gu, Zhuo Hai, Tianren Wang and Yun-Hui Liu

Biosensors 2022, 12(9), 766; https://doi.org/10.3390/bios12090766 - 19 Sep 2022

Cited by 7 | Viewed by 2954

Abstract

Oocyte vitrification technology is widely used for assisted reproduction and fertility preservation, which requires precise washing sequences and timings of cryoprotectant agents (CPAs) treatment to relieve the osmotic shock to cells. The gold standard Cryotop method is extensively used in oocyte vitrification and [...] Read more.

Oocyte vitrification technology is widely used for assisted reproduction and fertility preservation, which requires precise washing sequences and timings of cryoprotectant agents (CPAs) treatment to relieve the osmotic shock to cells. The gold standard Cryotop method is extensively used in oocyte vitrification and is currently the most commonly used method in reproductive centers. However, the Cryotop method requires precise and complex manual manipulation by an embryologist, whose proficiency directly determines the effect of vitrification. Therefore, in this study, an automatic microfluidic system consisting of a novel open microfluidic chip and a set of automatic devices was established as a standardized operating protocol to facilitate the conventional manual Cryotop method and minimize the osmotic shock applied to the oocyte. The proposed open microfluidic system could smoothly change the CPA concentration around the oocyte during vitrification pretreatment, and transferred the treated oocyte to the Cryotop with a tiny droplet. The system better conformed to the operating habits of embryologists, whereas the integration of commercialized Cryotop facilitates the subsequent freezing and thawing processes. With standardized operating procedures, our system provides consistent treatment effects for each operation, leading to comparable survival rate, mitochondrial membrane potential (MMP) and reactive oxygen species (ROS) level of oocytes to the manual Cryotop operations. The vitrification platform is the first reported microfluidic system integrating the function of cells transfer from the processing chip, which avoids the risk of cell loss or damage in a manual operation and ensures the sufficient cooling rate during liquid nitrogen (

{LN}_{2}

) freezing. Our study demonstrates significant potential of the automatic microfluidic approach to serve as a facile and universal solution for the vitrification of various precious cells. Full article

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

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15 pages, 3715 KiB

Open AccessArticle

Escherichia coli Enumeration in a Capillary-Driven Microfluidic Chip with SERS

by Üzeyir Dogan, Ferah Sucularlı, Ender Yildirim, Demet Cetin, Zekiye Suludere, Ismail Hakkı Boyaci and Ugur Tamer

Biosensors 2022, 12(9), 765; https://doi.org/10.3390/bios12090765 - 17 Sep 2022

Cited by 9 | Viewed by 2914

Abstract

Pathogen detection is still a challenging issue for public health, especially in food products. A selective preconcentration step is also necessary if the target pathogen concentration is very low or if the sample volume is limited in the analysis. Plate counting (24–48 h) [...] Read more.

Pathogen detection is still a challenging issue for public health, especially in food products. A selective preconcentration step is also necessary if the target pathogen concentration is very low or if the sample volume is limited in the analysis. Plate counting (24–48 h) methods should be replaced by novel biosensor systems as an alternative reliable pathogen detection technique. The usage of a capillary-driven microfluidic chip is an alternative method for pathogen detection, with the combination of surface-enhanced Raman scattering (SERS) measurements. Here, we constructed microchambers with capillary microchannels to provide nanoparticle–pathogen transportation from one chamber to the other. Escherichia coli (E. coli) was selected as a model pathogen and specific antibody-modified magnetic nanoparticles (MNPs) as a capture probe in a complex milk matrix. MNPs that captured E. coli were transferred in a capillary-driven microfluidic chip consisting of four chambers, and 4-aminothiophenol (4-ATP)-labelled gold nanorods (Au NRs) were used as the Raman probe in the capillary-driven microfluidic chip. The MNPs provided immunomagnetic (IMS) separation and preconcentration of analytes from the sample matrix and then, 4-ATP-labelled Au NRs provided an SERS response by forming sandwich immunoassay structures in the last chamber of the capillary-driven microfluidic chip. The developed SERS-based method could detect 10¹–10⁷ cfu/mL of E. coli with the total analysis time of less than 60 min. Selectivity of the developed method was also tested by using Salmonella enteritidis (S. enteritidis) and Staphylococcus aureus (S. aureus) as analytes, and very weak signals were observed. Full article

(This article belongs to the Special Issue Advances and New Perspectives in Micro-Nanofabricated Sensors for Bioanalysis)

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13 pages, 3200 KiB

Open AccessArticle

A Highly Integrated and Diminutive Fluorescence Detector for Point-of-Care Testing: Dual Negative Feedback Light-Emitting Diode (LED) Drive and Photoelectric Processing Circuits Design and Implementation

by Yue Wang, Yile Fang, Haoran Liu, Xiangyi Su, Zhu Chen, Song Li and Nongyue He

Biosensors 2022, 12(9), 764; https://doi.org/10.3390/bios12090764 - 16 Sep 2022

Cited by 5 | Viewed by 2755

Abstract

As an important detection tool in biochemistry, fluorescence detection has wide applications. Quantitative detection can be achieved by detecting fluorescence signals excited by excitation light at a specific wavelength range. Therefore, the key to fluorescence detection is the stable control of the excitation [...] Read more.

As an important detection tool in biochemistry, fluorescence detection has wide applications. Quantitative detection can be achieved by detecting fluorescence signals excited by excitation light at a specific wavelength range. Therefore, the key to fluorescence detection is the stable control of the excitation light and the accurate acquisition of weak photoelectric signals. Moreover, to improve portability and instantaneity, devices are developing in miniaturization and integration. As the core of such devices, fluorescence detectors should also have these features. Under this circumstance, we designed a highly integrated and diminutive fluorescence detector and focused on its excitation light driving and photoelectric signal processing. A current–light dual negative feedback light-emitting diode (LED) driving circuit was proposed to obtain constant current and luminance. In addition, a silicon photodiode (PD) was used to receive and convert the fluorescence signal to an electric signal. Then, amplifying, filtering, and analog-to-digital (A/D) converting were applied to make the detection of weak fluorescence signals possible. The test results showed that the designed circuit has wonderful performance, and the detector shows good linearity (R² = 0.9967) and sensitivity (LOD = 0.077 nM) in the detection of fluorescein sodium solution. Finally, a real-time fluorescence polymerase chain reaction (real-time PCR) of Legionella pneumophila was carried out on a homemade platform equipped with this detector, indicating that the detector met the requirements of real-time PCR detection. Full article

(This article belongs to the Special Issue Materials and Techniques for Bioanalysis and Biosensing)

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24 pages, 5312 KiB

Open AccessArticle

Comparative Analysis of Cell Metabolic Activity Sensing by Escherichia coli rrnB P1-lux and Cd Responsive-Lux Biosensors: Time-Resolved Experiments and Mechanistic Modelling

by Eva Delatour, Christophe Pagnout, Marie L. Zaffino and Jérôme F. L. Duval

Biosensors 2022, 12(9), 763; https://doi.org/10.3390/bios12090763 - 16 Sep 2022

Cited by 4 | Viewed by 2242

Abstract

Whole-cell bacterial sensors are used in medical/environmental applications to detect chemicals, and to assess medium toxicity or stress. Non-specific constitutive biosensors generally serve the latter purpose, whereas chemical detection is performed with biosensors involving a specific chemical-inducible promoter. Herein, we show that functioning [...] Read more.

Whole-cell bacterial sensors are used in medical/environmental applications to detect chemicals, and to assess medium toxicity or stress. Non-specific constitutive biosensors generally serve the latter purpose, whereas chemical detection is performed with biosensors involving a specific chemical-inducible promoter. Herein, we show that functioning principles of specific and non-specific whole-cell biosensors are not exclusive as both can probe modulations of cell metabolic activity under stressing conditions. The demonstration is based on (i) time-resolved measurements of bioluminescence produced by constitutive rrnB P1-luxCDABE Escherichia coli biosensor in media differing with respect to carbon source, (ii) theoretical reconstruction of the measured signals using a here-reported theory for bioluminescence generated by constitutive cells, (iii) comparison between time-dependent cell photoactivity (reflecting metabolic activity) retrieved by theory with that we reported recently for cadmium-inducible PzntA-luxCDABE E. coli in media of similar compositions. Whereas signals of constitutive and non-constitutive biosensors differ in terms of shape, amplitude and peak number depending on nutritional medium conditions, analysis highlights the features shared by their respective cell photoactivity patterns mediated by the interplay between stringent response and catabolite repressions. The work advocates for the benefits of a theoretical interpretation for the time-dependent response of biosensors to unravel metabolic and physicochemical contributions to the bioluminescence signal. Full article

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

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34 pages, 7448 KiB

Open AccessReview

Recent Advances in Nanomechanical Membrane-Type Surface Stress Sensors towards Artificial Olfaction

by Kosuke Minami, Gaku Imamura, Ryo Tamura, Kota Shiba and Genki Yoshikawa

Biosensors 2022, 12(9), 762; https://doi.org/10.3390/bios12090762 - 16 Sep 2022

Cited by 19 | Viewed by 3957

Abstract

Nanomechanical sensors have gained significant attention as powerful tools for detecting, distinguishing, and identifying target analytes, especially odors that are composed of a complex mixture of gaseous molecules. Nanomechanical sensors and their arrays are a promising platform for artificial olfaction in combination with [...] Read more.

Nanomechanical sensors have gained significant attention as powerful tools for detecting, distinguishing, and identifying target analytes, especially odors that are composed of a complex mixture of gaseous molecules. Nanomechanical sensors and their arrays are a promising platform for artificial olfaction in combination with data processing technologies, including machine learning techniques. This paper reviews the background of nanomechanical sensors, especially conventional cantilever-type sensors. Then, we focus on one of the optimized structures for static mode operation, a nanomechanical Membrane-type Surface stress Sensor (MSS), and discuss recent advances in MSS and their applications towards artificial olfaction. Full article

(This article belongs to the Special Issue Nanomechanical Sensors for Gas Detection)

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17 pages, 3889 KiB

Open AccessArticle

Development of New Simple Compositions of Silver Inks for the Preparation of Pseudo-Reference Electrodes

by Jéssica R. Camargo, Wilson S. Fernandes-Junior, Déborah C. Azzi, Raquel G. Rocha, Lucas V. Faria, Eduardo M. Richter, Rodrigo A. A. Muñoz and Bruno C. Janegitz

Biosensors 2022, 12(9), 761; https://doi.org/10.3390/bios12090761 - 16 Sep 2022

Cited by 12 | Viewed by 3094

Abstract

Silver materials are known to present excellent properties, such as high electrical and thermal conductivity as well as chemical stability. Silver-based inks have drawn a lot of attention for being compatible with various substrates, which can be used in the production uniform and [...] Read more.

Silver materials are known to present excellent properties, such as high electrical and thermal conductivity as well as chemical stability. Silver-based inks have drawn a lot of attention for being compatible with various substrates, which can be used in the production uniform and stable pseudo-reference electrodes with low curing temperatures. Furthermore, the interest in the use of disposable electrodes has been increasing due to the low cost and the possibility of their use in point-of-care and point-of-need situations. Thus, in this work, two new inks were developed using Ag as conductive material and colorless polymers (nail polish (NP) and shellac (SL)), and applied to different substrates (screen-printed electrodes, acetate sheets, and 3D-printed electrodes) to verify the performance of the proposed inks. Measurements attained with open circuit potential (OCP) attested to the stability of the potential of the pseudo-reference proposed for 1 h. Analytical curves for β-estradiol were also obtained using the devices prepared with the proposed inks as pseudo-references electrodes, which presented satisfactory results concerning the potential stability (RSD < 2.6%). These inks are simple to prepare and present great alternatives for the development of pseudo-reference electrodes useful in the construction of disposable electrochemical systems. Full article

(This article belongs to the Special Issue Advances and New Perspectives in Micro-Nanofabricated Sensors for Bioanalysis)

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13 pages, 2381 KiB

Open AccessArticle

Electrochemical Determination of 4-Bromophenoxyacetic Acid Based on CeO₂/eGr Composite

by Haijun Du, Yan Zhang, Xin Wang, Huali Hu, Jixing Ai, Huanxi Zhou, Xia Yan, Yang Yang and Zhiwei Lu

Biosensors 2022, 12(9), 760; https://doi.org/10.3390/bios12090760 - 15 Sep 2022

Cited by 4 | Viewed by 1997

Abstract

The determination of plant growth regulators is of great importance for the quality monitoring of crops. In this work, 4-bromophenoxyacetic acid (4-BPA), one of the phenoxyacetic acids, was detected via the electrochemical method for the first time. A CeO₂-decorated electrochemical exfoliated [...] Read more.

The determination of plant growth regulators is of great importance for the quality monitoring of crops. In this work, 4-bromophenoxyacetic acid (4-BPA), one of the phenoxyacetic acids, was detected via the electrochemical method for the first time. A CeO₂-decorated electrochemical exfoliated graphene (eGr) composite (CeO₂/eGr) was constructed as the sensor for sensitive detection of 4-BPA due to the synergistic effect of the excellent catalytic active sites of CeO₂ and good electron transference of the eGr. The developed CeO₂/eGr sensor displayed a good linearity in a wide range from 0.3 to 150 μmol/L and the lowest detection limit of 0.06 μmol/L for 4-BPA detection. Electrochemical oxidation of 4-BPA follows a mix-controlled process on the CeO₂/eGr electrode, which involves 2e in the transference process. This developed CeO₂/eGr sensor has excellent repeatability with a relative standard deviation (RSD) of 2.35% in 10 continuous measurements. Moreover, the practical application of the sensor for 4-BPA detection in apple juice has recoveries in the range of 90–108%. This proposed CeO₂/eGr sensor has great potential for detecting plant growth regulators in the agricultural industry. Full article

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

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11 pages, 3929 KiB

Open AccessCommunication

High-Sensitive FAM Labeled Aptasensor Based on Fe₃O₄/Au/g-C₃N₄ for the Detection of Sulfamethazine in Food Matrix

by Xueling Yan, Lulan Yang, Jiaming Tang, Xu Wen, Xingyue Chen, Xiaoling Zheng, Lingling Chen, Jiaqi Li and Tao Le

Biosensors 2022, 12(9), 759; https://doi.org/10.3390/bios12090759 - 15 Sep 2022

Cited by 5 | Viewed by 2079

Abstract

In this study, we developed a fluorescent aptasensor based on Fe₃O₄/Au/g-C₃N₄ and a FAM-labeled aptamer (FAM-SMZ1S) against sulfamethazine (SMZ) for the specific and sensitive detection of SMZ in food matrix. The FAM-SMZ1S was adsorbed by the [...] Read more.

In this study, we developed a fluorescent aptasensor based on Fe₃O₄/Au/g-C₃N₄ and a FAM-labeled aptamer (FAM-SMZ1S) against sulfamethazine (SMZ) for the specific and sensitive detection of SMZ in food matrix. The FAM-SMZ1S was adsorbed by the Fe₃O₄/Au/g-C₃N₄ via π–π stacking and electrostatic adsorption, serving as a basis for the ultrasensitive detection of SMZ. Molecular dynamics was used to explain the reasons why SMZ1S and SMZ were combined. This aptasensor presented sensitive recognition performance, with a limit of detection of 0.16 ng/mL and a linear range of 1–100 ng/mL. The recovery rate ranged from 91.6% to 106.8%, and the coefficient of variation (CV) ranged from 2.8% to 13.4%. In addition, we tested the aptasensor for the monitoring of SMZ in various matrix samples, and the results were well-correlated (R² ≥ 0.9153) with those obtained for HPLC detection. According to these results, the aptasensor was sensitive and accurate, representing a potentially useful tool for the detection of SMZ in food matrix. Full article

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

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25 pages, 4791 KiB

Open AccessReview

Liquid Crystal Droplet-Based Biosensors: Promising for Point-of-Care Testing

by Ruwen Xie, Na Li, Zunhua Li, Jinrong Chen, Kaixuan Li, Qiang He, Lishang Liu and Shusheng Zhang

Biosensors 2022, 12(9), 758; https://doi.org/10.3390/bios12090758 - 15 Sep 2022

Cited by 14 | Viewed by 4968

Abstract

The development of biosensing platforms has been impressively accelerated by advancements in liquid crystal (LC) technology. High response rate, easy operation, and good stability of the LC droplet-based biosensors are all benefits of the long-range order of LC molecules. Bioprobes emerged when LC [...] Read more.

The development of biosensing platforms has been impressively accelerated by advancements in liquid crystal (LC) technology. High response rate, easy operation, and good stability of the LC droplet-based biosensors are all benefits of the long-range order of LC molecules. Bioprobes emerged when LC droplets were combined with biotechnology, and these bioprobes are used extensively for disease diagnosis, food safety, and environmental monitoring. The LC droplet biosensors have high sensitivity and excellent selectivity, making them an attractive tool for the label-free, economical, and real-time detection of different targets. Portable devices work well as the accessory kits for LC droplet-based biosensors to make them easier to use by anyone for on-site monitoring of targets. Herein, we offer a review of the latest developments in the design of LC droplet-based biosensors for qualitative target monitoring and quantitative target analysis. Full article

(This article belongs to the Special Issue Materials and Techniques for Bioanalysis and Biosensing)

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15 pages, 3501 KiB

Open AccessArticle

Implementation of an Integrated Dielectrophoretic and Magnetophoretic Microfluidic Chip for CTC Isolation

by Kai Zhao, Penglu Zhao, Jianhong Dong, Yunman Wei, Bin Chen, Yanjuan Wang, Xinxiang Pan and Junsheng Wang

Biosensors 2022, 12(9), 757; https://doi.org/10.3390/bios12090757 - 14 Sep 2022

Cited by 16 | Viewed by 2963

Abstract

Identification of circulating tumor cells (CTCs) from a majority of various cell pools has been an appealing topic for diagnostic purposes. This study numerically demonstrates the isolation of CTCs from blood cells by the combination of dielectrophoresis and magnetophoresis in a microfluidic chip. [...] Read more.

Identification of circulating tumor cells (CTCs) from a majority of various cell pools has been an appealing topic for diagnostic purposes. This study numerically demonstrates the isolation of CTCs from blood cells by the combination of dielectrophoresis and magnetophoresis in a microfluidic chip. Taking advantage of the label-free property, the separation of red blood cells, platelets, T cells, HT-29, and MDA-231 was conducted in the microchannel. By using the ferromagnet structure with double segments and a relatively shorter distance in between, a strong gradient of the magnetic field, i.e., sufficiently large MAP forces acting on the cells, can be generated, leading to a high separation resolution. In order to generate strong DEP forces, the non-uniform electric field gradient is induced by applying the electric voltage through the microchannel across a pair of asymmetric orifices, i.e., a small orifice and a large orifice on the opposite wall of the channel sides. The distribution of the gradient of the magnetic field near the edge of ferromagnet segments, the gradient of the non-uniform electric field in the vicinity of the asymmetric orifices, and the flow field were investigated. In this numerical simulation, the effects of the ferromagnet structure on the magnetic field, the flow rate, as well as the strength of the electric field on their combined magnetophoretic and dielectrophoretic behaviors and trajectories are systemically studied. The simulation results demonstrate the potential of both property- and size-based cell isolation in the microfluidic device by implementing magnetophoresis and dielectrophoresis. Full article

(This article belongs to the Special Issue Advanced Microfluidic Chips and Their Applications)

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15 pages, 3318 KiB

Open AccessArticle

Ultra-Sensitive and Semi-Quantitative Vertical Flow Assay for the Rapid Detection of Interleukin-6 in Inflammatory Diseases

by Rongwei Lei, Hufsa Arain, Maryam Obaid, Nivriti Sabhnani and Chandra Mohan

Biosensors 2022, 12(9), 756; https://doi.org/10.3390/bios12090756 - 14 Sep 2022

Cited by 8 | Viewed by 3245

Abstract

The inflammation biomarker Interleukin 6 (IL-6) exhibits a concentration of less than 7 pg/mL in healthy serum but increases 10–100-fold when inflammation occurs. Increased serum IL-6 has been reported in chronic diseases such as rheumatoid arthritis (RA), as well as in life-threatening acute [...] Read more.

The inflammation biomarker Interleukin 6 (IL-6) exhibits a concentration of less than 7 pg/mL in healthy serum but increases 10–100-fold when inflammation occurs. Increased serum IL-6 has been reported in chronic diseases such as rheumatoid arthritis (RA), as well as in life-threatening acute illnesses such as sepsis and cytokine release syndrome (CRS). This work seeks to meet the demand for rapid detection of serum IL-6 both for rapid monitoring of chronic diseases and for triaging patients with acute illnesses. Following the optimization of several types of gold nanoparticles, membrane pore sizes, and buffer systems, an ultra-sensitive vertical flow assay (VFA) was engineered, allowing the detection of recombinant IL-6 in spiked buffer with a limit of detection (LoD) of 10 pg/mL and a reportable range of 10–10,000 pg/mL with a 15-min assay time. The detection of IL-6 in spiked pooled healthy serum exhibited an LoD of 3.2 pg/mL and a reportable range of 10–10,000 pg/mL. The VFA’s stability was demonstrated over 1-day, two-week, four-week, and six-week storage durations at room temperature. The inter-operator CV and intra-operator CV were determined to be 14.3% and 15.2%, respectively. Three reference zones, high, low, and blank, were introduced into the cartridge to facilitate on-site semi-quantitative measurements across a 6-point semi-quantitative range. Finally, the performance of the IL-6 VFA was validated using 20 RA and 20 healthy control (HC) clinical serum samples, using ELISA as the gold standard platform. The ultra-sensitive, rapid IL-6 VFA could potentially be used to triage patients for intensive care, treatment adjustments, or for monitoring disease activity in inflammatory conditions. Full article

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

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18 pages, 3570 KiB

Open AccessArticle

The Utilization of Tunable Transducer Elements Formed by the Manipulation of Magnetic Beads with Different Sizes via Optically Induced Dielectrophoresis (ODEP) for High Signal-to-Noise Ratios (SNRs) and Multiplex Fluorescence-Based Biosensing Applications

by Chia-Ming Yang, Jian-Cyun Yu, Po-Yu Chu, Chia-Hsun Hsieh and Min-Hsien Wu

Biosensors 2022, 12(9), 755; https://doi.org/10.3390/bios12090755 - 14 Sep 2022

Cited by 10 | Viewed by 2170

Abstract

Magnetic beads improve biosensing performance by means of their small volume and controllability by magnetic force. In this study, a new technique composed of optically induced dielectrodphoresis (ODEP) manipulation and image processing was used to enhance the signal-to-noise ratio of the fluorescence for [...] Read more.

Magnetic beads improve biosensing performance by means of their small volume and controllability by magnetic force. In this study, a new technique composed of optically induced dielectrodphoresis (ODEP) manipulation and image processing was used to enhance the signal-to-noise ratio of the fluorescence for stained magnetic beads. According to natural advantages of size-dependent particle isolation by ODEP manipulation, biomarkers in clinical samples can be easily separated by different sizes of magnetic beads with corresponding captured antibodies, and rapidly distinguished by separated location of immunofluorescence. To verify the feasibility of the concept, magnetic beads with three different diameters, including 21.8, 8.7, and 4.2 μm, were easily separated and collected into specific patterns in the defined target zone treated as three dynamic transducer elements to evaluate fluorescence results. In magnetic beads with diameter of 4.2 μm, the lowest signal-to-noise ratio between stained and nonstained magnetic beads was 3.5. With the help of ODEP accumulation and detection threshold setting of 32, the signal-to-noise ratio was increased to 77.4, which makes this method more reliable. With the further optimization of specific antibodies immobilized on different-size magnetic beads in the future, this platform can be a potential candidate for a high-efficiency sensor array in clinical applications. Full article

(This article belongs to the Section Biosensor Materials)

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18 pages, 5159 KiB

Open AccessReview

Recent Progress of Perovskite Nanocrystals in Chem/Bio Sensing

by Dailu Jia, Meng Xu, Shuang Mu, Wei Ren and Chenghui Liu

Biosensors 2022, 12(9), 754; https://doi.org/10.3390/bios12090754 - 14 Sep 2022

Cited by 11 | Viewed by 3551

Abstract

Perovskite nanocrystals (PNCs) are endowed with extraordinary photophysical properties such as wide absorption spectra, high quantum yield, and narrow emission bands. However, the inherent shortcomings, especially the instability in polar solvents and water incompatibility, have hindered their application as probes in chem/bio sensing. [...] Read more.

Perovskite nanocrystals (PNCs) are endowed with extraordinary photophysical properties such as wide absorption spectra, high quantum yield, and narrow emission bands. However, the inherent shortcomings, especially the instability in polar solvents and water incompatibility, have hindered their application as probes in chem/bio sensing. In this review, we give a fundamental understanding of the challenges when using PNCs for chem/bio sensing and summarize recent progress in this area, including the application of PNCs in various sensors and the corresponding strategies to maintain their structural integrity. Finally, we provide perspectives to promote the future development of PNCs for chem/bio sensing applications. Full article

(This article belongs to the Special Issue Advances in Quantum Dots Biosensing)

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10 pages, 1423 KiB

Open AccessArticle

The Feasibility of Early Alzheimer’s Disease Diagnosis Using a Neural Network Hybrid Platform

by Xinke Yu, Siddharth Srivastava, Shan Huang, Eric Y. Hayden, David B. Teplow and Ya-Hong Xie

Biosensors 2022, 12(9), 753; https://doi.org/10.3390/bios12090753 - 13 Sep 2022

Cited by 8 | Viewed by 3131

Abstract

Early diagnosis of Alzheimer’s Disease (AD) is critical for disease prevention and cure. However, currently, techniques with the required high sensitivity and specificity are lacking. Recently, with the advances and increased accessibility of data analysis tools, such as machine learning, research efforts have [...] Read more.

Early diagnosis of Alzheimer’s Disease (AD) is critical for disease prevention and cure. However, currently, techniques with the required high sensitivity and specificity are lacking. Recently, with the advances and increased accessibility of data analysis tools, such as machine learning, research efforts have increasingly focused on using these computational methods to solve this challenge. Here, we demonstrate a convolutional neural network (CNN)-based AD diagnosis approach using the surface-enhanced Raman spectroscopy (SERS) fingerprints of human cerebrospinal fluid (CSF). SERS and CNN were combined for biomarker detection to analyze disease-associated biochemical changes in the CSF. We achieved very high reproducibility in double-blind experiments for testing the feasibility of our system on human samples. We achieved an overall accuracy of 92% (100% for normal individuals and 88.9% for AD individuals) based on the clinical diagnosis. Further, we observed an excellent correlation coefficient between our test score and the Clinical Dementia Rating (CDR) score. Our findings offer a substantial indication of the feasibility of detecting AD biomarkers using the innovative combination of SERS and machine learning. We are hoping that this will serve as an incentive for future research in the field. Full article

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

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24 pages, 6684 KiB

Open AccessArticle

Non-Invasive Microwave-Based Imaging System for Early Detection of Breast Tumours

by Carolina Blanco-Angulo, Andrea Martínez-Lozano, Roberto Gutiérrez-Mazón, Carlos G. Juan, Héctor García-Martínez, Julia Arias-Rodríguez, José M. Sabater-Navarro and Ernesto Ávila-Navarro

Biosensors 2022, 12(9), 752; https://doi.org/10.3390/bios12090752 - 12 Sep 2022

Cited by 9 | Viewed by 3197

Abstract

This work introduces a microwave-based system able to detect tumours in breast phantoms in a non-invasive way. The data acquisition system is composed of a hardware system which involves high-frequency components (antennas, switches and cables), a microcontroller, a vector network analyser used as [...] Read more.

This work introduces a microwave-based system able to detect tumours in breast phantoms in a non-invasive way. The data acquisition system is composed of a hardware system which involves high-frequency components (antennas, switches and cables), a microcontroller, a vector network analyser used as measurement instrument and a computer devoted to the control and automation of the operation of the system. Concerning the software system, the computer runs a Python script which is in charge of mastering and automatising all the required stages for the data acquisition, from initialisation of the hardware system to performing and saving the measurements. We also report on the design of the high-performance broadband antenna used to carry out the measurements, as well as on the algorithm employed to build the final medical images, based on an adapted version of the so-called Improved Delay-and-Sum (IDAS) algorithm improved by a Hamming window filter and averaging preprocessing. The calibration and start-up of the system are also described. The experimental validation includes the use of different tumour models with different dielectric properties inside the breast phantom. The results show promising tumour detection capabilities, even when there is low dielectric contrast between the tumoural and healthy tissues, as is the usual case for dense breasts in young women. Full article

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

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16 pages, 780 KiB

Open AccessArticle

EEG Evaluation in a Neuropsychological Intervention Program Based on Virtual Reality in Adults with Parkinson’s Disease

by Daniela Muñoz, Patricio Barria, Carlos A. Cifuentes, Rolando Aguilar, Karim Baleta, José M. Azorín and Marcela Múnera

Biosensors 2022, 12(9), 751; https://doi.org/10.3390/bios12090751 - 12 Sep 2022

Cited by 2 | Viewed by 3364

Abstract

Nowadays, several strategies for treating neuropsychologic function loss in Parkinson’s disease (PD) have been proposed, such as physical activity performance and developing games to exercise the mind. However, few studies illustrate the incidence of these therapies in neuronal activity. This work aims to [...] Read more.

Nowadays, several strategies for treating neuropsychologic function loss in Parkinson’s disease (PD) have been proposed, such as physical activity performance and developing games to exercise the mind. However, few studies illustrate the incidence of these therapies in neuronal activity. This work aims to study the feasibility of a virtual reality-based program oriented to the cognitive functions’ rehabilitation of PD patients. For this, the study was divided into intervention with the program, acquisition of signals, data processing, and results analysis. The alpha and beta bands’ power behavior was determined by evaluating the electroencephalography (EEG) signals obtained during the execution of control tests and games of the “Hand Physics Lab” Software, from which five games related to attention, planning, and sequencing, concentration, and coordination were taken. Results showed the characteristic performance of the cerebral bands during resting states and activity states. In addition, it was determined that the beta band increased its activity in all the cerebral lobes in all the tested games (p-value < 0.05). On the contrary, just one game exhibited an adequate performance of the alpha band activity of the temporal and frontal lobes (p-value < 0.02). Furthermore, the visual attention and the capacity to process and interpret the information given by the surroundings was favored during the execution of trials (p-value < 0.05); thus, the efficacy of the virtual reality program to recover cognitive functions was verified. The study highlights implementing new technologies to rehabilitate people with neurodegenerative diseases. Full article

(This article belongs to the Special Issue Biosensors in Rehabilitation and Assistance Robotics)

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17 pages, 3571 KiB

Open AccessReview

Strategies for Enhancing the Sensitivity of Electrochemiluminescence Biosensors

by Yueyue Huang, Yuanyuan Yao, Yueliang Wang, Lifen Chen, Yanbo Zeng, Lei Li and Longhua Guo

Biosensors 2022, 12(9), 750; https://doi.org/10.3390/bios12090750 - 11 Sep 2022

Cited by 16 | Viewed by 3662

Abstract

Electrochemiluminescence (ECL) has received considerable attention as a powerful analytical technique for the sensitive and accurate detection of biological analytes owing to its high sensitivity and selectivity and wide dynamic range. To satisfy the growing demand for ultrasensitive analysis techniques with high efficiency [...] Read more.

Electrochemiluminescence (ECL) has received considerable attention as a powerful analytical technique for the sensitive and accurate detection of biological analytes owing to its high sensitivity and selectivity and wide dynamic range. To satisfy the growing demand for ultrasensitive analysis techniques with high efficiency and accuracy in complex real sample matrices, considerable efforts have been dedicated to developing ECL strategies to improve the sensitivity of bioanalysis. As one of the most effective approaches, diverse signal amplification strategies have been integrated with ECL biosensors to achieve desirable analytical performance. This review summarizes the recent advances in ECL biosensing based on various signal amplification strategies, including DNA-assisted amplification strategies, efficient ECL luminophores, surface-enhanced electrochemiluminescence, and ratiometric strategies. Sensitivity-enhancing strategies and bio-related applications are discussed in detail. Moreover, the future trends and challenges of ECL biosensors are discussed. Full article

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

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11 pages, 3189 KiB

Open AccessArticle

Unraveling the Secrets of Colistin Resistance with Label-Free Raman Spectroscopy

by Dimple Saikia, Priyanka Jadhav, Arti R. Hole, Chilakapati Murali Krishna and Surya P. Singh

Biosensors 2022, 12(9), 749; https://doi.org/10.3390/bios12090749 - 11 Sep 2022

Cited by 6 | Viewed by 2902

Abstract

The rise in number of infections from multidrug-resistant (MDR) Gram-negative microbes has led to an increase in the use of a variety of ‘polymyxins’ such as colistin. Even though colistin is known to cause minor nephro- and neuro-toxicity, it is still considered as [...] Read more.

The rise in number of infections from multidrug-resistant (MDR) Gram-negative microbes has led to an increase in the use of a variety of ‘polymyxins’ such as colistin. Even though colistin is known to cause minor nephro- and neuro-toxicity, it is still considered as last resort antibiotic for treating MDR infections. In this study, we have applied Raman spectroscopy to understand the differences among colistin sensitive and resistant bacterial strains at community level. We have successfully generated colistin resistant clones and verified the presence of resistance-causing MCR-1 plasmid. A unique spectral profile associated with specific drug concentration has been obtained. Successful delineation between resistant and sensitive cells has also been achieved via principal component analysis. Overall findings support the prospective utility of Raman spectroscopy in identifying anti-microbial resistance. Full article

(This article belongs to the Special Issue Raman Spectroscopy for Clinics)

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5 pages, 408 KiB

Open AccessEditorial

Conjugated Polymers-Based Biosensors for Virus Detection: Lessons from COVID-19

by Vinh Van Tran

Biosensors 2022, 12(9), 748; https://doi.org/10.3390/bios12090748 - 10 Sep 2022

Cited by 7 | Viewed by 2127

Abstract

Human beings continue to endure the coronavirus disease (COVID-19) pandemic, which has spread throughout the world and significantly affected all countries and territories, causing a socioeconomic crunch. Human pathogenic viruses are considered a global burden for public health, both in the present and [...] Read more.

Human beings continue to endure the coronavirus disease (COVID-19) pandemic, which has spread throughout the world and significantly affected all countries and territories, causing a socioeconomic crunch. Human pathogenic viruses are considered a global burden for public health, both in the present and the future. Therefore, the early and accurate diagnosis of viruses has been and still is critical and should be accorded a degree of priority that is equivalent to vaccinations and drugs. We have opened a Special Issue titled “Conjugated polymers-based biosensors for virus detection”. This editorial seeks to emphasize the importance and potential of conjugated polymers in the design and development of biosensors. Furthermore, we briefly provide an overview, scientific evidence, and opinions on promising strategies for the development of CP-based electrochemical biosensors for virus detection. Full article

(This article belongs to the Special Issue Conjugated Polymers-Based Biosensors for Virus Detection)

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11 pages, 3199 KiB

Open AccessArticle

Facile Label-Free Electrochemical DNA Biosensor for Detection of Osteosarcoma-Related Survivin Gene

by Yao Chen, Yu Zhong, Ji-Xing Ye, Yun Lei and Ai-Lin Liu

Biosensors 2022, 12(9), 747; https://doi.org/10.3390/bios12090747 - 9 Sep 2022

Cited by 5 | Viewed by 2092

Abstract

A sensitive and selective electrochemical deoxyribonucleic acid (DNA) biosensor was developed for the determination of a osteosarcoma-related survivin gene by using celestine blue (CB) as a label-free hybridization indicator. The proposed strategy adopted a facile and low-cost working electrode with no need for [...] Read more.

A sensitive and selective electrochemical deoxyribonucleic acid (DNA) biosensor was developed for the determination of a osteosarcoma-related survivin gene by using celestine blue (CB) as a label-free hybridization indicator. The proposed strategy adopted a facile and low-cost working electrode with no need for other substances for electrode or DNA functionalization. The interaction mode between CB and DNA was studied by electrochemical and spectroscopic approaches, illustrating that the possible mode was intercalation with a binding number of 2 and a binding constant β of 10^12.87. Moreover, the label-free electrochemical DNA biosensor exhibited a good linear relationship toward the target gene in a range from 1.00 nM to 50.00 nM with a detection limit as low as 0.046 nM using 3σ estimating system. This facile and low-cost electrochemical method realized the rapid detection and accurate quantification of the target sequence in complicated serum samples, endowing its promising potential in the diagnosis and monitoring of genetic diseases. Full article

(This article belongs to the Special Issue DNA Based Biosensors and Related Applications)

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14 pages, 2326 KiB

Open AccessArticle

Ultrasensitive and Rapid Detection of N-Terminal Pro-B-Type Natriuretic Peptide (NT-proBNP) Using Fiber Optic Nanogold-Linked Immunosorbent Assay

by Han-Long Liu, Yen-Ta Tseng, Mei-Chu Lai and Lai-Kwan Chau

Biosensors 2022, 12(9), 746; https://doi.org/10.3390/bios12090746 - 9 Sep 2022

Cited by 10 | Viewed by 2892

Abstract

The N-terminal pro-brain natriuretic peptide (NT-proBNP) is considered an important blood biomarker for heart failure. Herein, we report about a fiber optic nanogold-linked immunosorbent assay (FONLISA) method for the rapid, sensitive, and low-cost detection of NT-proBNP. The method is based on a sandwich [...] Read more.

The N-terminal pro-brain natriuretic peptide (NT-proBNP) is considered an important blood biomarker for heart failure. Herein, we report about a fiber optic nanogold-linked immunosorbent assay (FONLISA) method for the rapid, sensitive, and low-cost detection of NT-proBNP. The method is based on a sandwich immunoassay approach that uses two monoclonal NT-proBNP antibodies, a capture antibody (Ab^C), and a detection antibody (Ab^D). Ab^D is conjugated to a free gold nanoparticle (AuNP) to form the free AuNP@Ab^D conjugate, and Ab^C is immobilized on an unclad segment of an optical fiber. The detection of analyte (A), in this case NT-proBNP, is based on the signal change due to the formation of an AuNP@Ab^D–A–Ab^C complex on the fiber core surface, where a green light transmitted through the optical fiber will decrease in intensity due to light absorption by AuNPs via the localized surface plasmon resonance effect. This method provides a wide linear dynamic range of 0.50~5000 pg·mL⁻¹ and a limit of detection of 0.058 pg·mL⁻¹ for NT-proBNP. Finally, the method exhibits good correlation (r = 0.979) with the commercial central laboratory-based electrochemiluminescent immunoassay method that uses a Roche Cobas e411 instrument. Hence, our method is potentially a suitable tool for point-of-care testing. Full article

(This article belongs to the Special Issue Photonics-Based Biosensors for Environmental, Food Safety and Biomedical Applications)

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13 pages, 4214 KiB

Open AccessArticle

Detection of Pb²⁺ in Tea Using Aptamer Labeled with AIEgen Nanospheres Based on MOFs Sensors

by Li Gao, Yixi Deng, Haolu Liu, King Solomon, Bianjiang Zhang and Huimei Cai

Biosensors 2022, 12(9), 745; https://doi.org/10.3390/bios12090745 - 9 Sep 2022

Cited by 13 | Viewed by 2666

Abstract

Tea is an important economic crop and health beverage in China. The presence of heavy metal ions in tea poses a significant threat to public health. Here, we prepared an aptamer biosensor labelled with AIEgen nanospheres to detect Pb²⁺ in tea. The [...] Read more.

Tea is an important economic crop and health beverage in China. The presence of heavy metal ions in tea poses a significant threat to public health. Here, we prepared an aptamer biosensor labelled with AIEgen nanospheres to detect Pb²⁺ in tea. The dsDNA modified by amino and phosphoric acid was combined with the carboxylated AIEgen NPs to form AIEgen-DNA with a fluorescence group, which was then fixed to the surface of Zr-MOFs to quench the fluorescence of AIEgen NPs. At the same time, PEG was added to remove nonspecific adsorption. Then Pb²⁺ was added to cut the DNA sequences containing the cutting sites, and AIEgen NPs and part of the DNA sequences were separated from the Zr-MOFs surface to recover the fluorescence. By comparing the fluorescence changes before and after adding Pb²⁺, the detection limit of Pb²⁺ can reach 1.70 nM. The fluorescence sensor was applied to detect Pb²⁺ in tea, and the detection results showed that the tea purchased on the market did not contain the concentration of Pb²⁺ within the detection range. This study provides new insights into monitoring food and agriculture-related pollutants based on fluorescent biosensors. Full article

(This article belongs to the Special Issue Advances and New Perspectives in Micro-Nanofabricated Sensors for Bioanalysis)

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12 pages, 2978 KiB

Open AccessCommunication

Nanoparticle-Based Visual Detection of Amplified DNA for Diagnosis of Hepatitis C Virus

by Soo-Kyung Kim, Yoon-Hee Oh, Dae-Hyun Ko, Heungsup Sung, Heung-Bum Oh and Sang-Hyun Hwang

Biosensors 2022, 12(9), 744; https://doi.org/10.3390/bios12090744 - 9 Sep 2022

Cited by 13 | Viewed by 2957

Abstract

Rapid, simple, and inexpensive diagnostic point-of-care tests (POCTs) are essential for controlling infectious diseases in resource-limited settings. In this study, we developed a new detection system based on nanoparticle–DNA aggregation (STat aggregation of tagged DNA, STAT-DNA) to yield a visual change that can [...] Read more.

Rapid, simple, and inexpensive diagnostic point-of-care tests (POCTs) are essential for controlling infectious diseases in resource-limited settings. In this study, we developed a new detection system based on nanoparticle–DNA aggregation (STat aggregation of tagged DNA, STAT-DNA) to yield a visual change that can be easily detected by the naked eye. This simplified optical detection system was applied to detect hepatitis C virus (HCV). Reverse transcription-polymerase chain reaction (RT-PCR) was performed using primers labeled with biotin and digoxigenin. Streptavidin-coated magnetic particles (1 μm) and anti-digoxigenin antibody-coated polystyrene particles (250–350 nm) were added to form aggregates. The limit of detection (LoD) and analytical specificity were analyzed. The STAT-DNA results were compared with those of the standard real-time PCR assay using serum samples from 54 patients with hepatitis C. We achieved visualization of amplified DNA with the naked eye by adding nanoparticles to the PCR mixture without employing centrifugal force, probe addition, incubation, or dilution. The LoD of STAT-DNA was at least 10¹ IU/mL. STAT-DNA did not show cross-reactivity with eight viral pathogens. The detection using STAT-DNA was consistent with that using standard real-time PCR. Full article

(This article belongs to the Section Biosensors and Healthcare)

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24 pages, 4028 KiB

Open AccessReview

Biomedical Applications of an Ultra-Sensitive Surface Plasmon Resonance Biosensor Based on Smart MXene Quantum Dots (SMQDs)

by Seyyed Mojtaba Mousavi, Seyyed Alireza Hashemi, Masoomeh Yari Kalashgrani, Vahid Rahmanian, Ahmad Gholami, Wei-Hung Chiang and Chin Wei Lai

Biosensors 2022, 12(9), 743; https://doi.org/10.3390/bios12090743 - 9 Sep 2022

Cited by 20 | Viewed by 4414

Abstract

In today’s world, the use of biosensors occupies a special place in a variety of fields such as agriculture and industry. New biosensor technologies can identify biological compounds accurately and quickly. One of these technologies is the phenomenon of surface plasmon resonance (SPR) [...] Read more.

In today’s world, the use of biosensors occupies a special place in a variety of fields such as agriculture and industry. New biosensor technologies can identify biological compounds accurately and quickly. One of these technologies is the phenomenon of surface plasmon resonance (SPR) in the development of biosensors based on their optical properties, which allow for very sensitive and specific measurements of biomolecules without time delay. Therefore, various nanomaterials have been introduced for the development of SPR biosensors to achieve a high degree of selectivity and sensitivity. The diagnosis of deadly diseases such as cancer depends on the use of nanotechnology. Smart MXene quantum dots (SMQDs), a new class of nanomaterials that are developing at a rapid pace, are perfect for the development of SPR biosensors due to their many advantageous properties. Moreover, SMQDs are two-dimensional (2D) inorganic segments with a limited number of atomic layers that exhibit excellent properties such as high conductivity, plasmonic, and optical properties. Therefore, SMQDs, with their unique properties, are promising contenders for biomedicine, including cancer diagnosis/treatment, biological sensing/imaging, antigen detection, etc. In this review, SPR biosensors based on SMQDs applied in biomedical applications are discussed. To achieve this goal, an introduction to SPR, SPR biosensors, and SMQDs (including their structure, surface functional groups, synthesis, and properties) is given first; then, the fabrication of hybrid nanoparticles (NPs) based on SMQDs and the biomedical applications of SMQDs are discussed. In the next step, SPR biosensors based on SMQDs and advanced 2D SMQDs-based nanobiosensors as ultrasensitive detection tools are presented. This review proposes the use of SMQDs for the improvement of SPR biosensors with high selectivity and sensitivity for biomedical applications. Full article

(This article belongs to the Special Issue Plasmonic Sensors: A New Frontier in Nanotechnology)

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13 pages, 1509 KiB

Open AccessArticle

A Luciferase Mutant with Improved Brightness and Stability for Whole-Cell Bioluminescent Biosensors and In Vitro Biosensing

by Maria Maddalena Calabretta, Denise Gregucci, Héctor Martínez-Pérez-Cejuela and Elisa Michelini

Biosensors 2022, 12(9), 742; https://doi.org/10.3390/bios12090742 - 9 Sep 2022

Cited by 16 | Viewed by 4802

Abstract

The availability of new bioluminescent proteins with tuned properties, both in terms of emission wavelength, kinetics and protein stability, is highly valuable in the bioanalytical field, with the potential to improve the sensitivity and analytical performance of the currently used methods for ATP [...] Read more.

The availability of new bioluminescent proteins with tuned properties, both in terms of emission wavelength, kinetics and protein stability, is highly valuable in the bioanalytical field, with the potential to improve the sensitivity and analytical performance of the currently used methods for ATP detection, whole-cell biosensors, and viability assays among others. We present a new luciferase mutant, called BgLuc, suitable for developing whole-cell biosensors and in vitro biosensors characterized by a bioluminescence maximum of 548 nm, narrow emission bandwidth, favorable kinetic properties, and excellent pH- and thermo-stabilities at 37 and 45 °C and pH from 5.0 to 8.0. We assessed the suitability of this new luciferase for whole-cell biosensing with a cell-based bioreporter assay for Nuclear Factor-kappa B (NF-kB) signal transduction pathway using 2D and 3D human embryonic kidney (HEK293T) cells, and for ATP detection with the purified enzyme. In both cases the luciferase showed suitable for sensitive detection of the target analytes, with better or similar performance than the commercial counterparts. Full article

(This article belongs to the Special Issue Cell-Based Biosensors for Rapid Detection and Monitoring)

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21 pages, 26821 KiB

Open AccessArticle

Nanomaterials as Redox Mediators in Laccase-Based Amperometric Biosensors for Catechol Assay

by Olha Demkiv, Galina Gayda, Nataliya Stasyuk, Olena Brahinetz, Mykhailo Gonchar and Marina Nisnevitch

Biosensors 2022, 12(9), 741; https://doi.org/10.3390/bios12090741 - 8 Sep 2022

Cited by 9 | Viewed by 2640

Abstract

Laccase is a copper-containing enzyme that does not require hydrogen peroxide as a co-substrate or additional cofactors for an enzymatic reaction. Nanomaterials of various chemical structures are usually applied to the construction of enzyme-based biosensors. Metals, metal oxides, semiconductors, and composite NPs perform [...] Read more.

Laccase is a copper-containing enzyme that does not require hydrogen peroxide as a co-substrate or additional cofactors for an enzymatic reaction. Nanomaterials of various chemical structures are usually applied to the construction of enzyme-based biosensors. Metals, metal oxides, semiconductors, and composite NPs perform various functions in electrochemical transformation schemes as a platform for the enzyme immobilization, a mediator of an electron transfer, and a signal amplifier. We describe here the development of amperometric biosensors (ABSs) based on laccase and redox-active micro/nanoparticles (hereafter—NPs), which were immobilized on a graphite electrode (GE). For this purpose, we isolated a highly purified enzyme from the fungus Trametes zonatus, and then synthesized bi- and trimetallic NPs of noble and transition metals, as well as hexacyanoferrates (HCF) of noble metals; these were layered onto the surfaces of GEs. The electroactivity of many of the NPs immobilized on the GEs was characterized by cyclic voltammetry (CV) experiments. The most effective mediators of electron transfer were selected as the platform for the development of laccase-based ABSs. As a result, a number of catechol-sensitive ABSs were constructed and characterized. The laccase/CuCo/GE was demonstrated to possess the highest sensitivity to catechol (4523 A·M⁻¹·m⁻²) among the tested ABSs. The proposed ABSs may be promising for the analysis of phenolic derivatives in real samples of drinking water, wastewater, and food products. Full article

(This article belongs to the Special Issue Recent Progress in Nanomaterial-Enhanced Biosensing)

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