Chemosensors

15 pages, 1054 KiB

Open AccessArticle

A Hairpin DNA-Based Piezoelectric E-Nose: Exploring the Performances of Heptamer Loops for the Detection of Volatile Organic Compounds

by Sara Gaggiotti, Marcello Mascini, Angelo Cichelli, Michele Del Carlo and Dario Compagnone

Chemosensors 2021, 9(5), 115; https://doi.org/10.3390/chemosensors9050115 - 20 May 2021

Cited by 2 | Viewed by 2580

Abstract

A hairpin DNA (hpDNA) piezoelectric gas sensors array with heptamer loops as sensing elements was designed, realized, and challenged with pure volatile organic compounds VOCs and real samples (beer). The virtual binding versus five chemical classes (alcohols, aldehydes, esters, hydrocarbons, and ketones) of [...] Read more.

A hairpin DNA (hpDNA) piezoelectric gas sensors array with heptamer loops as sensing elements was designed, realized, and challenged with pure volatile organic compounds VOCs and real samples (beer). The virtual binding versus five chemical classes (alcohols, aldehydes, esters, hydrocarbons, and ketones) of the entire combinatorial library of heptamer loops (16,384 elements) was studied by molecular modelling. Six heptamer loops, having the largest variance in binding the chemical classes, were selected to build the array. The six gas sensors were realized by immobilizing onto gold nanoparticles (AuNPs) via a thiol spacer the hpDNA constituted by the heptamer loops and the same double helix stem of four base pairs (GAAG at 5′ and CTTC at 3′ end). The HpDNA-AuNP was used to modify the surface of 20 MHz quartz crystal microbalances (QCMs). The realized E-nose was able to clearly discriminate among 15 pure VOCs of different chemical classes, as demonstrated by hierarchical cluster analysis. The analysis of real beer samples during fermentation was also carried out. In such a challenging matrix consisting of 23 different VOCs, the hpDNA E-nose with heptamer loops was able to discriminate among different fermentation times with high success rate. Class assignment using the Bayes theorem gave an excellent 98% correct beer samples classification in cross-validation. Full article

(This article belongs to the Collection Recent Advances in Multifunctional Sensing Technology for Gas Analysis)

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12 pages, 1484 KiB

Open AccessArticle

Optimized 3D Finite-Difference-Time-Domain Algorithm to Model the Plasmonic Properties of Metal Nanoparticles with Near-Unity Accuracy

by Mehran Rafiee, Subhash Chandra, Hind Ahmed and Sarah J. McCormack

Chemosensors 2021, 9(5), 114; https://doi.org/10.3390/chemosensors9050114 - 20 May 2021

Cited by 4 | Viewed by 3797

Abstract

The finite difference time domain (FDTD) method is a grid-based, robust, and straightforward method to model the optical properties of metal nanoparticles (MNPs). Modelling accuracy and optical properties can be enhanced by increasing FDTD grid resolution; however, the resolution of the grid size [...] Read more.

The finite difference time domain (FDTD) method is a grid-based, robust, and straightforward method to model the optical properties of metal nanoparticles (MNPs). Modelling accuracy and optical properties can be enhanced by increasing FDTD grid resolution; however, the resolution of the grid size is limited by the memory and computational requirements. In this paper, a 3D optimized FDTD (OFDTD) was designed and developed, which introduced new FDTD approximation terms based on the physical events occurring during the plasmonic oscillations in MNP. The proposed method not only required ~52% less memory than conventional FDTD, but also reduced the calculation requirements by ~9%. The 3D OFDTD method was used to model and obtain the extinction spectrum, localized surface plasmon resonance (LSPR) frequency, and the electric field enhancement factor (EF) for spherical silver nanoparticles (Ag NPs). The model’s predicted results were compared with traditional FDTD as well as experimental results to validate the model. The OFDTD results were found to be in excellent agreement with the experimental results. The EF accuracy was improved by 74% with respect to FDTD simulation, which helped reaching a near-unity OFDTD accuracy of ~99%. The

λ_{L S P R}

discrepancy reduced from 20 nm to 3 nm. The EF peak position discrepancy improved from ±5.5 nm to only ±0.5 nm. Full article

(This article belongs to the Special Issue Innovative Materials, Technologies, and Sensors)

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Graphical abstract

8 pages, 2446 KiB

Open AccessCommunication

CH₃SH and H₂S Sensing Properties of V₂O₅/WO₃/TiO₂ Gas Sensor

by Takafumi Akamatsu, Toshio Itoh, Akihiro Tsuruta and Yoshitake Masuda

Chemosensors 2021, 9(5), 113; https://doi.org/10.3390/chemosensors9050113 - 19 May 2021

Cited by 14 | Viewed by 3419

Abstract

Resistive-type semiconductor-based gas sensors were fabricated for the detection of methyl mercaptan and hydrogen sulfide. To fabricate these sensors, V₂O₅/WO₃/TiO₂ (VWT) particles were deposited on interdigitated Pt electrodes. The vanadium oxide content of the utilized VWT [...] Read more.

Resistive-type semiconductor-based gas sensors were fabricated for the detection of methyl mercaptan and hydrogen sulfide. To fabricate these sensors, V₂O₅/WO₃/TiO₂ (VWT) particles were deposited on interdigitated Pt electrodes. The vanadium oxide content of the utilized VWT was 1.5, 3, or 10 wt.%. The structural properties of the VWT particles were investigated by X-ray diffraction and scanning electron microscopy analyses. The resistance of the VWT gas sensor decreased with increasing methyl mercaptan and hydrogen sulfide gas concentrations in the range of 50 to 500 ppb. The VWT gas sensor with 3 wt.% vanadium oxide showed high methyl mercaptan and hydrogen sulfide responses and good gas selectivity against hydrogen at 300 °C. Full article

(This article belongs to the Special Issue Nanomaterials Synthesis for Both Sensors and Environmental Applications)

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15 pages, 7698 KiB

Open AccessArticle

Antioxidant and Antiradical Properties of Some Examples of Flavonoids and Coumarins—Potentiometric Studies

by Elena Gerasimova, Elena Gazizullina, Ekaterina Radosteva and Alla Ivanova

Chemosensors 2021, 9(5), 112; https://doi.org/10.3390/chemosensors9050112 - 18 May 2021

Cited by 9 | Viewed by 2797

Abstract

A comprehensive study of a range of flavonoids and coumarins is presented in this article. The work uses an approach that evaluates the activity of these compounds by various mechanisms: the electron transfer (ET), the hydrogen atom transfer (HAT), and the mechanism of [...] Read more.

A comprehensive study of a range of flavonoids and coumarins is presented in this article. The work uses an approach that evaluates the activity of these compounds by various mechanisms: the electron transfer (ET), the hydrogen atom transfer (HAT), and the mechanism of metal chelation. The studies were carried out using the methods of the cyclic voltammetry and the potentiometry. The electrochemical behavior of these compounds was studied by the method of cyclic voltammetry; the main types of voltammograms, depending on the oxidation mechanisms, were identified. Various versions of potentiometric sensor systems have been used to detect analytical signal in approaches implemented in ET, HAT and metal chelation mechanisms. The antioxidant capacity was studied by the electron-transfer mechanism. Compounds with antioxidant properties were selected; half-reaction periods for these compounds have been determined. It has been shown that electron-donating and complexing properties directly depend on the mutual arrangement of hydroxyl groups in the molecule. The antiradical ability of the compounds has been studied. It was shown that all studied compounds inhibit peroxyl radicals. Series on the change in antioxidant and antiradical properties of compounds have been compiled. There is no correlation between the results of the study of antioxidant properties obtained using sensory systems that reveal various antioxidant mechanisms. The need to use an integrated approach in the study of antioxidant properties is shown. Full article

(This article belongs to the Special Issue Electrochemical Sensors for Antioxidant/Oxidant Activity Monitoring)

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11 pages, 3946 KiB

Open AccessArticle

Charge Transfer on the Surface-Enhanced Raman Scattering of Ag/4-MBA/PEDOT:PSS System: Intermolecular Hydrogen Bonding

by Yuenan Pan, Wei Wang, Shuang Guo, Sila Jin, Eungyeong Park, Yantao Sun, Lei Chen and Young Mee Jung

Chemosensors 2021, 9(5), 111; https://doi.org/10.3390/chemosensors9050111 - 17 May 2021

Cited by 11 | Viewed by 3217

Abstract

A sandwich-structured noble metal-probe molecule-organic semiconductor consisting of Ag nanoparticles (NPs), 4-mercaptobenzoic acid (4-MBA) and different concentrations of poly(styrenesulfonate:poly(3,4-ethylenedioxythiophene) (PEDOT:PSS) was prepared by layer-by-layer assembly. Intermolecular hydrogen bonding was observed to have a significant effect on the surface-enhanced Raman scattering (SERS) of Ag/4-MBA/PEDOT:PSS. [...] Read more.

A sandwich-structured noble metal-probe molecule-organic semiconductor consisting of Ag nanoparticles (NPs), 4-mercaptobenzoic acid (4-MBA) and different concentrations of poly(styrenesulfonate:poly(3,4-ethylenedioxythiophene) (PEDOT:PSS) was prepared by layer-by-layer assembly. Intermolecular hydrogen bonding was observed to have a significant effect on the surface-enhanced Raman scattering (SERS) of Ag/4-MBA/PEDOT:PSS. Upon increasing the PEDOT:PSS concentration, the characteristic Raman band intensity of 4-MBA was enhanced. In addition, the selected b₂ vibration mode was significantly enhanced due to the influence of the charge transfer (CT) mechanism. The CT degree (ρ_CT) of the composite system was calculated before and after doping with PEDOT:PSS; when the concentration of PEDOT:PSS was 0.8%, the SERS intensity tended to be stable, and ρ_CT reached a maximum. Compared with that of the undoped PEDOT:PSS system, ρ_CT was significantly enhanced after doping, which can be explained by the CT effect induced by hydrogen bonds. These results indicate that hydrogen bonding transfers a charge from the Fermi energy level of Ag to the lowest unoccupied molecular orbital (LUMO) of 4-MBA, and due to the resulting potential difference, the charge will continue to transfer to the LUMO of PEDOT:PSS. Therefore, the introduction of organic semiconductors into the field of SERS not only expands the SERS substrate scope, but also provides a new idea for exploring the SERS mechanism. In addition, the introduction of hydrogen bonds has become an important guide for the study of CT and the structure of composite systems. Full article

(This article belongs to the Section Optical Chemical Sensors)

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14 pages, 3000 KiB

Open AccessArticle

Potentiometric Electronic Tongue for Pharmaceutical Analytics: Determination of Ascorbic Acid Based on Electropolymerized Films

by Gabriela Broncová, Vadim Prokopec and Tatiana V. Shishkanova

Chemosensors 2021, 9(5), 110; https://doi.org/10.3390/chemosensors9050110 - 14 May 2021

Cited by 5 | Viewed by 2808

Abstract

This work deals with the design of an experimental potentiometric electronic tongue (ET) for the recognition of various samples of effervescent tablets with different ascorbic acid (vitamin C) contents. The ET consisted of twelve potentiometric sensors based on conductive polymers, which were derived [...] Read more.

This work deals with the design of an experimental potentiometric electronic tongue (ET) for the recognition of various samples of effervescent tablets with different ascorbic acid (vitamin C) contents. The ET consisted of twelve potentiometric sensors based on conductive polymers, which were derived from 4-amino-2,1,3-benzothiadiazole, 3,4-diaminobenzoic acid, and neutral red on the surface of the platinum electrode using cyclic voltammetry. The aim of the potentiometric study was to assess the influence of the vitamin C content and the composition of the matrix of commercial samples on the potentiometric response. The results obtained from the sensor array proved that the stability of the potentiometric signal and the accuracy of measurements are affected by individual sensors. The identification of the vitamin C content in the individual samples of effervescent tablets obtained by means of the potentiometric electronic tongue corresponded with the results of the coulometric titration. Full article

(This article belongs to the Special Issue Functionalized Materials for Chemosensor Applications)

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22 pages, 4877 KiB

Open AccessReview

Photoluminescent Metal Complexes and Materials as Temperature Sensors—An Introductory Review

by John W. Kenney III and Jae Joon Lee

Chemosensors 2021, 9(5), 109; https://doi.org/10.3390/chemosensors9050109 - 14 May 2021

Cited by 11 | Viewed by 3192

Abstract

Temperature is a fundamental physical quantity whose accurate measurement is of critical importance in virtually every area of science, engineering, and biomedicine. Temperature can be measured in many ways. In this pedagogically focused review, we briefly discuss various standard contact thermometry measurement techniques. [...] Read more.

Temperature is a fundamental physical quantity whose accurate measurement is of critical importance in virtually every area of science, engineering, and biomedicine. Temperature can be measured in many ways. In this pedagogically focused review, we briefly discuss various standard contact thermometry measurement techniques. We introduce and touch upon the necessity of non-contact thermometry, particularly for systems in extreme environments and/or in rapid motion, and how luminescence thermometry can be a solution to this need. We review the various aspects of luminescence thermometry, including different types of luminescence measurements and the numerous materials used as luminescence sensors. We end the article by highlighting other physical quantities that can be measured by luminescence (e.g., pressure, electric field strength, magnetic field strength), and provide a brief overview of applications of luminescence thermometry in biomedicine. Full article

(This article belongs to the Special Issue Luminescent Metal Complexes as Sensors)

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26 pages, 8544 KiB

Open AccessEditor’s ChoiceReview

Current Trends in Polymer Based Sensors

by Giancarla Alberti, Camilla Zanoni, Vittorio Losi, Lisa Rita Magnaghi and Raffaela Biesuz

Chemosensors 2021, 9(5), 108; https://doi.org/10.3390/chemosensors9050108 - 13 May 2021

Cited by 64 | Viewed by 6997

Abstract

This review illustrates various types of polymer and nanocomposite polymeric based sensors used in a wide variety of devices. Moreover, it provides an overview of the trends and challenges in sensor research. As fundamental components of new devices, polymers play an important role [...] Read more.

This review illustrates various types of polymer and nanocomposite polymeric based sensors used in a wide variety of devices. Moreover, it provides an overview of the trends and challenges in sensor research. As fundamental components of new devices, polymers play an important role in sensing applications. Indeed, polymers offer many advantages for sensor technologies: their manufacturing methods are pretty simple, they are relatively low-cost materials, and they can be functionalized and placed on different substrates. Polymers can participate in sensing mechanisms or act as supports for the sensing units. Another good quality of polymer-based materials is that their chemical structure can be modified to enhance their reactivity, biocompatibility, resistance to degradation, and flexibility. Full article

(This article belongs to the Section Materials for Chemical Sensing)

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16 pages, 16594 KiB

Open AccessArticle

Anodic Stripping Voltammetry with the Hanging Mercury Drop Electrode for Trace Metal Detection in Soil Samples

by Kequan Xu, Clara Pérez-Ràfols, Amine Marchoud, María Cuartero and Gastón A. Crespo

Chemosensors 2021, 9(5), 107; https://doi.org/10.3390/chemosensors9050107 - 13 May 2021

Cited by 14 | Viewed by 5996

Abstract

The widely spread use of the hanging mercury drop electrode (HMDE) for multi-ion analysis is primarily ascribed to the following reasons: (i) excellent reproducibility owing to the easy renewal of the electrode surface avoiding any hysteresis effect (i.e., a new identical drop is [...] Read more.

The widely spread use of the hanging mercury drop electrode (HMDE) for multi-ion analysis is primarily ascribed to the following reasons: (i) excellent reproducibility owing to the easy renewal of the electrode surface avoiding any hysteresis effect (i.e., a new identical drop is generated for each measurement to be accomplished); (ii) a wide cathodic potential window originating from the passive hydrogen evolution and solvent electrolysis; (iii) the ability to form amalgams with many redox-active metal ions; and (iv) the achievement of (sub)nanomolar limits of detection. On the other hand, the main controversy of the HMDE usage is the high toxicity level of mercury, which has motivated the scientific community to question whether the HMDE deserves to continue being used despite its unique capability for multi-metal detection. In this work, the simultaneous determination of Zn²⁺, Cd²⁺, Pb²⁺, and Cu²⁺ using the HMDE is investigated as a model system to evaluate the main features of the technique. The analytical benefits of the HMDE in terms of linear range of response, reproducibility, limit of detection, proximity to ideal redox behavior of metal ions and analysis time are herein demonstrated and compared to other electrodes proposed in the literature as less-toxic alternatives to the HMDE. The results have revealed that the HMDE is largely superior to other reported methods in several aspects and, moreover, it displays excellent accuracy when simultaneously analyzing Zn²⁺, Cd²⁺, Pb²⁺, and Cu²⁺ in such a complex matrix as digested soils. Yet, more efforts are required towards the definitive replacement of the HMDE in the electroanalysis field, despite the elegant approaches already reported in the literature. Full article

(This article belongs to the Special Issue Modern Directions in Ion Electroanalysis for Real World Applications)

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11 pages, 3179 KiB

Open AccessArticle

A Surface Acoustic Wave Sensor with a Microfluidic Channel for Detecting C-Reactive Protein

by Ming-Jer Jeng, Ying-Chang Li, Mukta Sharma, Chia-Wei Chen, Chia-Lung Tsai, Yen-Heng Lin, Shiang-Fu Huang, Liann-Be Chang and Chao-Sung Lai

Chemosensors 2021, 9(5), 106; https://doi.org/10.3390/chemosensors9050106 - 10 May 2021

Cited by 9 | Viewed by 3322

Abstract

A surface acoustic wave (SAW) sensor with a microfluidic channel was studied to detect C-reactive protein (CRP). A piezoelectric lithium niobate substrate was used to examine the frequency response of the microfluidic SAW sensor. The amplitude (insertion loss) changes in the microfluidic SAW [...] Read more.

A surface acoustic wave (SAW) sensor with a microfluidic channel was studied to detect C-reactive protein (CRP). A piezoelectric lithium niobate substrate was used to examine the frequency response of the microfluidic SAW sensor. The amplitude (insertion loss) changes in the microfluidic SAW sensor were measured from the interaction of CRP/anti-CRP owing to mass variation. The fabricated microfluidic SAW sensor exhibited a detection limit of 4 ng/mL CRP concentration. A wide CRP concentration range (10 ng/mL to 0.1 mg/mL) can be detected by this sensor, which is higher than the existing CRP detection methods. A good linear relationship between the amplitude peak shift and CRP concentrations from 10 ng/mL to 0.1 mg/mL was obtained. The amplitude peak shifts in the sensor can be useful for estimating CRP concentration. This can be used as a biosensor to diagnose the risk of cardiovascular disease. Full article

(This article belongs to the Special Issue Selected Papers from the International Electron Devices & Materials Symposium 2020 (IEDMS 2020))

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23 pages, 3754 KiB

Open AccessReview

Sensitive Materials and Coating Technologies for Surface Acoustic Wave Sensors

by Alexandra Palla-Papavlu, Stefan Ioan Voicu and Maria Dinescu

Chemosensors 2021, 9(5), 105; https://doi.org/10.3390/chemosensors9050105 - 10 May 2021

Cited by 26 | Viewed by 4718

Abstract

Since their development, surface acoustic wave (SAW) devices have attracted much research attention due to their unique functional characteristics, which make them appropriate for the detection of chemical species. The scientific community has directed its efforts toward the development and integration of new [...] Read more.

Since their development, surface acoustic wave (SAW) devices have attracted much research attention due to their unique functional characteristics, which make them appropriate for the detection of chemical species. The scientific community has directed its efforts toward the development and integration of new materials as sensing elements in SAW sensor technology with a large area of applications, such as for example the detection of volatile organic compounds, warfare chemicals, or food spoilage, just to name a few. Thin films play an important role and are essential as recognition elements in sensor structures due to their wide range of capabilities. In addition, other requisites are the development and application of new thin film deposition techniques as well as the possibility to tune the size and properties of the materials. This review article surveys the latest progress in engineered complex materials, i.e., polymers or functionalized carbonaceous materials, for applications as recognizing elements in miniaturized SAW sensors. It starts with an overview of chemoselective polymers and the synthesis of functionalized carbon nanotubes and graphene, which is followed by surveys of various coating technologies and routes for SAW sensors. Different coating techniques for SAW sensors are highlighted, which provides new approaches and perspective to meet the challenges of sensitive and selective gas sensing. Full article

(This article belongs to the Special Issue Selective Acoustic Wave Sensors and their Applications)

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10 pages, 2051 KiB

Open AccessArticle

A MEMS µ-Preconcentrator Employing a Carbon Molecular Sieve Membrane for Highly Volatile Organic Compound Sampling

by Hung-Yen Kuo, Wei-Riu Cheng, Tzu-Heng Wu, Horn-Jiunn Sheen, Chih-Chia Wang and Chia-Jung Lu

Chemosensors 2021, 9(5), 104; https://doi.org/10.3390/chemosensors9050104 - 7 May 2021

Cited by 3 | Viewed by 2872

Abstract

This paper presents the synthesis and evaluation of a carbon molecular sieve membrane (CMSM) grown inside a MEMS-fabricated μ-preconcentrator for sampling highly volatile organic compounds. An array of µ-pillars measuring 100 µm in diameter and 250 µm in height were fabricated inside a [...] Read more.

This paper presents the synthesis and evaluation of a carbon molecular sieve membrane (CMSM) grown inside a MEMS-fabricated μ-preconcentrator for sampling highly volatile organic compounds. An array of µ-pillars measuring 100 µm in diameter and 250 µm in height were fabricated inside a microfluidic channel to increase the attaching surface for the CMSM. The surface area of the CMSM was measured as high as 899 m²/g. A GC peak amplification factor >2 × 10⁴ was demonstrated with gaseous ethyl acetate. Up to 1.4 L of gaseous ethanol at the 100 ppb level could be concentrated without exceeding the capacity of this microchip device. Sharp desorption chromatographic peaks (<3.5 s) were obtained while using this device directly as a GC injector. Less volatile compounds such as gaseous toluene, m-xylene, and mesitylene appeared to be adsorbed strongly on CMSM, showing a memory effect. Sampling parameters such as sample volatilities, sampling capacities, and compound residual issues were empirically determined and discussed. Full article

(This article belongs to the Special Issue Advances in Analytical Systems for Gaseous Mixture)

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12 pages, 2313 KiB

Open AccessArticle

Voltammetric Study of the Total Activity of Antioxidants in the Blood Serum of Patients with Neurological Diseases

by Olesya A. Voronova, Elena I. Korotkova, Evgenii V. Plotnikov, Alina V. Geraskevich, Nadegda G. Kataeva, Elena V. Dorozhko, Irina S. Gamayurova, Olga I. Lipskikh and Ksenia V. Derina

Chemosensors 2021, 9(5), 103; https://doi.org/10.3390/chemosensors9050103 - 7 May 2021

Cited by 2 | Viewed by 2381

Abstract

One of the main directions in the development of modern electroanalytical chemistry is the development of new effective methods for research and analysis of biological objects, particularly, human blood serum. The creation of new electrochemical sensors is a promising approach, which has determined [...] Read more.

One of the main directions in the development of modern electroanalytical chemistry is the development of new effective methods for research and analysis of biological objects, particularly, human blood serum. The creation of new electrochemical sensors is a promising approach, which has determined several main directions in applied voltammetry in the field of chemical analytical control. In this work, the dynamics and parameters of total antioxidant activity of human serum blood of patients with chronic cerebral ischemia, during treatment with pharmaceutical drugs Mexidol, Cavinton Comfort, and Cytoflavin was tested by cathode voltammetry with a model process of oxygen electroreduction, using a new electrochemical sensor. Full article

(This article belongs to the Special Issue Electrochemical Sensors for Antioxidant/Oxidant Activity Monitoring)

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29 pages, 5926 KiB

Open AccessArticle

Dual Transduction of H₂O₂ Detection Using ZnO/Laser-Induced Graphene Composites

by Julia Zanoni, Jorge P. Moura, Nuno F. Santos, Alexandre F. Carvalho, António J. S. Fernandes, Teresa Monteiro, Florinda M. Costa, Sónia O. Pereira and Joana Rodrigues

Chemosensors 2021, 9(5), 102; https://doi.org/10.3390/chemosensors9050102 - 5 May 2021

Cited by 15 | Viewed by 4280

Abstract

Zinc oxide (ZnO)/laser-induced graphene (LIG) composites were prepared by mixing ZnO, grown by laser-assisted flow deposition, with LIG produced by laser irradiation of a polyimide, both in ambient conditions. Different ZnO:LIG ratios were used to infer the effect of this combination on the [...] Read more.

Zinc oxide (ZnO)/laser-induced graphene (LIG) composites were prepared by mixing ZnO, grown by laser-assisted flow deposition, with LIG produced by laser irradiation of a polyimide, both in ambient conditions. Different ZnO:LIG ratios were used to infer the effect of this combination on the overall composite behavior. The optical properties, assessed by photoluminescence (PL), showed an intensity increase of the excitonic-related recombination with increasing LIG amounts, along with a reduction in the visible emission band. Charge-transfer processes between the two materials are proposed to justify these variations. Cyclic voltammetry (CV) and electrochemical impedance spectroscopy evidenced increased electron transfer kinetics and an electrochemically active area with the amount of LIG incorporated in the composites. As the composites were designed to be used as transducer platforms in biosensing devices, their ability to detect and quantify hydrogen peroxide (H₂O₂) was assessed by both PL and CV analysis. The results demonstrated that both methods can be employed for sensing, displaying slightly distinct operation ranges that allow extending the detection range by combining both transduction approaches. Moreover, limits of detection as low as 0.11 mM were calculated in a tested concentration range from 0.8 to 32.7 mM, in line with the values required for their potential application in biosensors. Full article

(This article belongs to the Collection Sustainable Metal Oxide Materials for Sensing Applications)

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40 pages, 6572 KiB

Open AccessReview

Progress in Metal-Organic Frameworks Facilitated Mercury Detection and Removal

by Muthaiah Shellaiah and Kien-Wen Sun

Chemosensors 2021, 9(5), 101; https://doi.org/10.3390/chemosensors9050101 - 4 May 2021

Cited by 37 | Viewed by 6320

Abstract

Metal Organic Frameworks (MOFs) are noted as exceptional candidates towards the detection and removal of specific analytes. MOFs were reported in particular for the detection/removal of environmental contaminants, such as heavy metal ions, toxic anions, hazardous gases, explosives, etc. Among heavy metal ions, [...] Read more.

Metal Organic Frameworks (MOFs) are noted as exceptional candidates towards the detection and removal of specific analytes. MOFs were reported in particular for the detection/removal of environmental contaminants, such as heavy metal ions, toxic anions, hazardous gases, explosives, etc. Among heavy metal ions, mercury has been noted as a global hazard because of its high toxicity in the elemental (Hg⁰), divalent cationic (Hg²⁺), and methyl mercury (CH₃Hg⁺) forms. To secure the environment and living organisms, many countries have imposed stringent regulations to monitor mercury at all costs. Regarding the detection/removal requirements of mercury, researchers have proposed and reported all kinds of MOFs-based luminescent/non-luminescent probes towards mercury. This review provides valuable information about the MOFs which have been engaged in detection and removal of elemental mercury and Hg²⁺ ions. Moreover, the involved mechanisms or adsorption isotherms related to sensors or removal studies are clarified for the readers. Finally, advantages and limitations of MOFs in mercury detection/removal are described together with future scopes. Full article

(This article belongs to the Special Issue Organic-Inorganic Hybrid Chemo- and Bio-Sensors)

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22 pages, 3156 KiB

Open AccessReview

Electronic Surveillance and Security Applications of Magnetic Microwires

by Valentina Zhukova, Paula Corte-Leon, Juan Maria Blanco, Mihail Ipatov, Julian Gonzalez and Arcady Zhukov

Chemosensors 2021, 9(5), 100; https://doi.org/10.3390/chemosensors9050100 - 30 Apr 2021

Cited by 33 | Viewed by 3070

Abstract

Applications in security and electronic surveillance require a combination of excellent magnetic softness with good mechanical and anticorrosive properties and low dimensionality. We overviewed the feasibility of using glass-coated microwires for electronic article surveillance and security applications, as well as different routes of [...] Read more.

Applications in security and electronic surveillance require a combination of excellent magnetic softness with good mechanical and anticorrosive properties and low dimensionality. We overviewed the feasibility of using glass-coated microwires for electronic article surveillance and security applications, as well as different routes of tuning the magnetic properties of individual microwires or microwire arrays, making them quite attractive for electronic article surveillance and security applications. We provide the routes for tuning the hysteresis loops’ nonlinearity by the magnetostatic interaction between the microwires in the arrays of different types of amorphous microwires. The presence of neighboring microwire (either Fe- or Co-based) significantly affects the hysteresis loop of the whole microwires array. In a microwires array containing magnetically bistable microwires, we observed splitting of the initially rectangular hysteresis loop with a number of Barkhausen jumps correlated with the number of magnetically bistable microwires. Essentially, nonlinear and irregular hysteresis loops have been observed in mixed arrays containing Fe- and Co-rich microwires. The obtained nonlinearity in hysteresis loops allowed to increase the harmonics and tune their magnetic field dependencies. On the other hand, several routes allowing to tune the switching field by either postprocessing or modifying the magnetoelastic anisotropy have been reviewed. Nonlinear hysteresis loops have been also observed upon devitrification of amorphous microwires. Semihard magnetic microwires have been obtained by annealing of Fe–Pt–Si microwires. The observed unique combination of magnetic properties together with thin dimensions and excellent mechanical and anticorrosive properties provide excellent perspectives for the use of glass-coated microwires for security and electronic surveillance applications. Full article

(This article belongs to the Special Issue Advances in Magnetic Sensors with Nanocomponents)

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21 pages, 3676 KiB

Open AccessReview

Advances in Wearable Chemosensors

by Panagiota Koralli and Dionysios E. Mouzakis

Chemosensors 2021, 9(5), 99; https://doi.org/10.3390/chemosensors9050099 - 29 Apr 2021

Cited by 9 | Viewed by 4339

Abstract

In this review, the latest research on wearable chemosensors is presented. In focus are the results from open literature, mainly from the last three years. The progress in wearable chemosensors is presented with attention drawn to the measuring technologies, their ability to provide [...] Read more.

In this review, the latest research on wearable chemosensors is presented. In focus are the results from open literature, mainly from the last three years. The progress in wearable chemosensors is presented with attention drawn to the measuring technologies, their ability to provide robust data, the manufacturing techniques, as well their autonomy and ability to produce power. However, from statistical studies, the issue of patients’ trust in these technologies has arisen. People do not trust their personal data be transferred, stored, and processed through the vastness of the internet, which allows for timely diagnosis and treatment. The issue of power consumption and autonomy of chemosensor-integrated devices is also studied and the most recent solutions to this problem thoroughly presented. Full article

(This article belongs to the Special Issue Chemical and Biosensors: A Theme Issue in Honor of Professor Otto S. Wolfbeis)

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19 pages, 5198 KiB

Open AccessEditor’s ChoiceReview

Recent Development in Nanomaterial-Based Electrochemical Sensors for Cholesterol Detection

by Hemraj Mahipati Yadav, Jong-Deok Park, Hyeong-Cheol Kang and Jae-Joon Lee

Chemosensors 2021, 9(5), 98; https://doi.org/10.3390/chemosensors9050098 - 29 Apr 2021

Cited by 27 | Viewed by 5682

Abstract

Functional nanomaterials have attracted significant attention in a variety of research fields (in particular, in the healthcare system) because of the easily controllable morphology, their high chemical and environmental stability, biocompatibility, and unique optoelectronic and sensing properties. The sensing properties of nanomaterials can [...] Read more.

Functional nanomaterials have attracted significant attention in a variety of research fields (in particular, in the healthcare system) because of the easily controllable morphology, their high chemical and environmental stability, biocompatibility, and unique optoelectronic and sensing properties. The sensing properties of nanomaterials can be used to detect biomolecules such as cholesterol. Over the past few decades, remarkable progress has been made in the production of cholesterol biosensors that contain nanomaterials as the key component. In this article, various nanomaterials for the electrochemical sensing of cholesterol were reviewed. Cholesterol biosensors are recognized tools in the clinical diagnosis of cardiovascular diseases (CVDs). The function of nanomaterials in cholesterol biosensors were thoroughly discussed. In this study, different pathways for the sensing of cholesterol with functional nanomaterials were investigated. Full article

(This article belongs to the Special Issue Microfluidic Biosensing Platform)

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12 pages, 2042 KiB

Open AccessArticle

Rapid and Sensitive Point of Care Detection of MRSA Genomic DNA by Nanoelectrokinetic Sensors

by Rania Oueslati, Yu Jiang, Jiangang Chen and Jayne Wu

Chemosensors 2021, 9(5), 97; https://doi.org/10.3390/chemosensors9050097 - 29 Apr 2021

Cited by 9 | Viewed by 2766

Abstract

Biosensors have shown great potential in realizing rapid, low cost, and portable on-site detection for diseases. This work reports the development of a new bioelectronic sensor called AC electrokinetics-based capacitive (ABC) biosensor, for the detection of genomic DNA (gDNA) of methicillin-resistant Staphylococcus aureus [...] Read more.

Biosensors have shown great potential in realizing rapid, low cost, and portable on-site detection for diseases. This work reports the development of a new bioelectronic sensor called AC electrokinetics-based capacitive (ABC) biosensor, for the detection of genomic DNA (gDNA) of methicillin-resistant Staphylococcus aureus (MRSA). The ABC sensor is based on interdigitated microelectrodes biofunctionalized with oligonucleotide probes. It uses a special AC signal for direct capacitive monitoring of topological change on nanostructured sensor surface, which simultaneously induces dielectrophoretic enrichment of target gDNAs. As a result, rapid and specific detection of gDNA/probe hybridization can be realized with high sensitivity. It requires no signal amplification such as labeling, hybridization chain reaction, or nucleic acid sequence-based amplification. This method involves only simple sample preparation. After optimization of nanostructured sensor surface and signal processing, the ABC sensor demonstrated fast turnaround of results (~10 s detection), excellent sensitivity (a detection limit of 4.7 DNA copies/µL MRSA gDNA), and high specificity, suitable for point of care diagnosis. As a bioelectronic sensor, the developed ABC sensors can be easily adapted for detections of other infectious agents. Full article

(This article belongs to the Section (Bio)chemical Sensing)

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12 pages, 2432 KiB

Open AccessArticle

A Paper-Based Potentiometric Platform for Determination of Water Hardness

by Mohammed L. Bouhoun, Pascal Blondeau, Yamina Louafi and Francisco J. Andrade

Chemosensors 2021, 9(5), 96; https://doi.org/10.3390/chemosensors9050096 - 28 Apr 2021

Cited by 12 | Viewed by 5852

Abstract

A novel paper-based potentiometric platform for the simple and fast monitoring of water hardness is presented. First, potentiometric ion-selective electrodes for calcium and magnesium printed on a paper substrate were built and optimized. These sensors, which display near-Nernstian sensitivity, were used for the [...] Read more.

A novel paper-based potentiometric platform for the simple and fast monitoring of water hardness is presented. First, potentiometric ion-selective electrodes for calcium and magnesium printed on a paper substrate were built and optimized. These sensors, which display near-Nernstian sensitivity, were used for the determination of the concentration of these cations and the calculation of the water hardness. Second, the incorporation of a solid-state reference electrode allowed building an integrated paper-based potentiometric cell for the determination of the hardness of artificial and real samples (mineral waters). The validation of the results shows good ability to predict hardness in the conventional scale. Truly decentralized measurements were demonstrated by integration of a miniaturized instrument and dedicated software in a portable device. The measurements were able to be performed in just under two minutes, including a two-point calibration. Since the method is simple to use and cost-effective, it can be implemented in domestic and industrial settings. Full article

(This article belongs to the Special Issue Paper-Based Sensors and Microfluidic Devices)

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14 pages, 4943 KiB

Open AccessArticle

Low-Cost Inkjet-Printed Temperature Sensors on Paper Substrate for the Integration into Natural Fiber-Reinforced Lightweight Components

by Johanna Zikulnig, Mohammed Khalifa, Lukas Rauter, Herfried Lammer and Jürgen Kosel

Chemosensors 2021, 9(5), 95; https://doi.org/10.3390/chemosensors9050095 - 27 Apr 2021

Cited by 14 | Viewed by 2764

Abstract

In a unique approach to develop a “green” solution for in-situ monitoring, low-cost inkjet-printed temperature sensors on paper substrate were fully integrated into natural fiber-reinforced lightweight components for which structural health monitoring is becoming increasingly important. The results showed that the sensors remained [...] Read more.

In a unique approach to develop a “green” solution for in-situ monitoring, low-cost inkjet-printed temperature sensors on paper substrate were fully integrated into natural fiber-reinforced lightweight components for which structural health monitoring is becoming increasingly important. The results showed that the sensors remained functional after the vacuum infusion process; furthermore, the integration of the sensors improved the mechanical integrity and stability of the lightweight parts, as demonstrated by tensile testing. To verify the qualification of the printed sensors for the target application, the samples were exposed to varying temperature and humidity conditions inside of a climate chamber. The sensors showed linear temperature dependence in the temperature range of interest (−20 to 60 °C) with a TCR ranging from 1.576 × 10⁻³ K⁻¹ to 1.713 × 10⁻³ K⁻¹. Furthermore, the results from the tests in humid environments indicated that the used paper-based sensors could be made almost insensitive to changes in ambient humidity by embedding them into fiber-reinforced lightweight materials. This study demonstrates the feasibility of fully integrating paper-based printed sensors into lightweight components, which paves the way towards integration of other highly relevant sensing devices, such as strain and humidity sensors, for structural health monitoring of smart, sustainable, and environmentally compatible lightweight composite materials. Full article

(This article belongs to the Special Issue Paper-Based Sensors and Microfluidic Devices)

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12 pages, 1282 KiB

Open AccessArticle

Determination of Trace Levels of Nickel(II) by Adsorptive Stripping Voltammetry Using a Disposable and Low-Cost Carbon Screen-Printed Electrode

by Víctor Padilla, Núria Serrano and José Manuel Díaz-Cruz

Chemosensors 2021, 9(5), 94; https://doi.org/10.3390/chemosensors9050094 - 26 Apr 2021

Cited by 20 | Viewed by 3677

Abstract

A commercial and disposable screen-printed carbon electrode (SPCE) has been proposed for a fast, simple and low-cost determination of Ni(II) at very low concentration levels by differential pulse adsorptive stripping voltammetry (DPAdSV) in the presence of dimethylglyoxime (DMG) as complexing agent. In contrast [...] Read more.

A commercial and disposable screen-printed carbon electrode (SPCE) has been proposed for a fast, simple and low-cost determination of Ni(II) at very low concentration levels by differential pulse adsorptive stripping voltammetry (DPAdSV) in the presence of dimethylglyoxime (DMG) as complexing agent. In contrast with previously proposed methods, the Ni(II)-DMG complex adsorbs directly on the screen-printed carbon surface, with no need of mercury, bismuth or antimony coatings. Well-defined stripping peaks and a linear dependence of the peak area on the concentration of Ni(II) was achieved in the range from 1.7 to 150 µg L⁻¹, with a limit of detection of 0.5 µg L⁻¹ using a deposition time of 120 s. An excellent reproducibility and repeatability with 0.3% (n = 3) and 1.5% (n = 15) relative standard deviation, respectively, were obtained. In addition, the suitability of the SPCE as sensing unit has been successfully assessed in a wastewater certificated reference material with remarkable trueness and very good reproducibility. Full article

(This article belongs to the Section Electrochemical Devices and Sensors)

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11 pages, 3199 KiB

Open AccessCommunication

Helix-Like Receptors for Perrhenate Recognition Forming Hydrogen Bonds with All Four Oxygen Atoms

by Boris S. Morozov, Anil Ravi, Aleksandr S. Oshchepkov, Tobias Rüffer, Heinrich Lang and Evgeny A. Kataev

Chemosensors 2021, 9(5), 93; https://doi.org/10.3390/chemosensors9050093 - 26 Apr 2021

Cited by 2 | Viewed by 2958

Abstract

Supramolecular recognition of perrhenate is a challenging task due to therelatively large size and low charge density of this anion. In this work, we design and synthesize a family of helix-like synthetic receptors that can bind perrhenate by forming hydrogen bonds with all [...] Read more.

Supramolecular recognition of perrhenate is a challenging task due to therelatively large size and low charge density of this anion. In this work, we design and synthesize a family of helix-like synthetic receptors that can bind perrhenate by forming hydrogen bonds with all four oxygen atoms of the anion. Among the investigated rigid helix-forming subunit derived from 1,1′-ferrocenedicarboxylic acid, 1,3-phenylenediacetic acid and 2,2′-(ethyne-1,2-diyl)dibenzoic acid, the latter one shows the best selectivity for perrhenate recognition. However, the receptor based on 1,1′-ferrocenedicarboxylic acid demonstrates selectivity to bind chloride in a 1:2 fashion. The properties of the receptors are investigated in the acetonitrile solution by using NMR, UV–Vis, and in the solid state by single crystal X-ray analysis. Full article

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Graphical abstract

15 pages, 3763 KiB

Open AccessArticle

Development of a Tri-Functional Nanoprobe for Background-Free SERS Detection of Sialic Acid on the Cell Surface

by Septila Renata, Nitish Verma, Zhijay Tu, Rong-Long Pan, Mario Hofmann and Chun-Hung Lin

Chemosensors 2021, 9(5), 92; https://doi.org/10.3390/chemosensors9050092 - 26 Apr 2021

Cited by 2 | Viewed by 3526

Abstract

Sialic acid (SA) on the surface of cells is indispensable in numerous physiological and pathological processes, and sensitive and reproducible detection of SA is crucial for diagnosis and therapy in many diseases. Here, we developed a tri-functional nanoprobe as a sensitive and straightforward [...] Read more.

Sialic acid (SA) on the surface of cells is indispensable in numerous physiological and pathological processes, and sensitive and reproducible detection of SA is crucial for diagnosis and therapy in many diseases. Here, we developed a tri-functional nanoprobe as a sensitive and straightforward surface-enhanced Raman spectroscopy (SERS) nanoprobe for sialoglycan detection on cell surfaces. The reporter was designed to provide three key functionalities that make it ideal for SA detection. First, we employed two recognition groups, phenylboronic acid and an ammonium group, that enhance SA recognition and capture efficiency. Second, we used cyano as the Raman reporter because it emits in the cellular Raman silent region. Finally, thiol acted as an anchoring agent to conjugate the reporter to silver nanocubes to provide SERS enhancement. Our molecular nanoprobe design demonstrated the ability to detect SA on the cell surface with high sensitivity and spatial resolution, opening up new routes to cellular diagnostics. Full article

(This article belongs to the Special Issue Latest Advances in Nanobiosensors: Novel Materials and Applications)

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Graphical abstract

18 pages, 747 KiB

Open AccessReview

Analytical Capabilities of Coulometric Sensor Systems in the Antioxidants Analysis

by Guzel Ziyatdinova and Herman Budnikov

Chemosensors 2021, 9(5), 91; https://doi.org/10.3390/chemosensors9050091 - 25 Apr 2021

Cited by 15 | Viewed by 4131

Abstract

The definition of antioxidants (AOs), their classification and properties as well as electrochemical sensor systems for AOs analysis are briefly discussed. The analytical capabilities of coulometric titration with electrogenerated titrants as sensor systems for AOs determination have been considered in detail. The attention [...] Read more.

The definition of antioxidants (AOs), their classification and properties as well as electrochemical sensor systems for AOs analysis are briefly discussed. The analytical capabilities of coulometric titration with electrogenerated titrants as sensor systems for AOs determination have been considered in detail. The attention focused on the individual AO quantification that was mainly used in the pharmaceutical analysis and estimation of total antioxidant parameters (total antioxidant capacity (TAC), ferric reducing power (FRP) and ceric reducing/antioxidant capacity (CRAC)) allowing the fast screening of the target samples including their quality control. The main advantages of coulometric sensor systems are pointed out. The selective quantification of individual AO in a complex matrix using a combination of chromatography with coulometric or coulometric array detection under potentiostatic mode is discussed. The future development of coulometric sensor systems for AOs analysis is focused on the application of novel coulometric titrants and the application of coulometric detection in flow injection analysis. Full article

(This article belongs to the Special Issue Electrochemical Sensors for Antioxidant/Oxidant Activity Monitoring)

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19 pages, 3487 KiB

Open AccessArticle

Metallo-Liposomes Derived from the [Ru(bpy)₃]²⁺ Complex as Nanocarriers of Therapeutic Agents

by Maria Luisa Moyá, Francisco José Ostos, Izamar Moreno, Diandra García, Paula Moreno-Gordillo, Ivan V. Rosado, Pilar López-Cornejo, José Antonio Lebrón and Manuel López-López

Chemosensors 2021, 9(5), 90; https://doi.org/10.3390/chemosensors9050090 - 25 Apr 2021

Cited by 7 | Viewed by 2867

Abstract

The obtaining of nanocarriers of gene material and small drugs is still an interesting research line. Side-effects produced by the toxicity of several pharmaceutics, the high concentrations needed to get therapeutic effects, or their excessive use by patients have motivated the search for [...] Read more.

The obtaining of nanocarriers of gene material and small drugs is still an interesting research line. Side-effects produced by the toxicity of several pharmaceutics, the high concentrations needed to get therapeutic effects, or their excessive use by patients have motivated the search for new nanostructures. For these reasons, cationic metallo-liposomes composed by phosphatidylcholine (PC), cholesterol (CHO) and RuC1C19 (a surfactant derived from the metallic complex [Ru(bpy)₃]²⁺) were prepared and characterized by using diverse techniques (zeta potential, dynamic light scattering and electronic transmission microscopy –TEM-). Unimodal or bimodal populations of spherical aggregates with small sizes were obtained depending on the composition of the liposomes. The presence of cholesterol favored the formation of small aggregates. ct-DNA was condensed in the presence of the liposomes investigated. In-vitro assays demonstrated the ability of these nanoaggregates to internalize into different cell lines. A positive gene transfection into human bone osteosarcoma epithelial cells (U2OS) was also observed. The RuC1C19 surfactant was used as sensor to quantify the binding of DNA to the liposomes. Doxorubicin was encapsulated into the metallo-liposomes, demonstrating their ability to be also used as nanocarriers of drugs. A relationship between then encapsulation percentage of the antibiotic and the composition of the aggregates has been established. Full article

(This article belongs to the Special Issue Nanostructured Devices for Biochemical Sensing)

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11 pages, 1564 KiB

Open AccessPerspective

Oxidative Free Radicals and Other Species: Selective Messengers with a Reactive Capacity for Unselective Tissue Damage

by Pankaj Vadgama

Chemosensors 2021, 9(5), 89; https://doi.org/10.3390/chemosensors9050089 - 24 Apr 2021

Cited by 5 | Viewed by 2936

Abstract

Oxygen and nitrogen free radicals (RONS) form an exceptionally reactive molecular assembly within eukaryote cells. This perspective article gives a combined overview of different facets of research covering molecular reactivity, resultant tissue damage and final tissue outcomes as they relate to major disease. [...] Read more.

Oxygen and nitrogen free radicals (RONS) form an exceptionally reactive molecular assembly within eukaryote cells. This perspective article gives a combined overview of different facets of research covering molecular reactivity, resultant tissue damage and final tissue outcomes as they relate to major disease. There is an emphasis on cardiovascular disease, as the damage processes are best liked to the pathology. The overriding importance of inflammation in driving damage across all tissues is highlighted. Brief coverage is also provided of measurement approaches, respectively for antioxidant status, using potentiometry, and voltammetry for selected target species. Whilst damage due to RONS is a common focus, the fundamental importance of RONS to biological signalling is also covered here as an indispensable basis for life. The article thus provides a global overview of this topic for anyone wishing to understand the current status across multiple fronts. Full article

(This article belongs to the Special Issue Electrochemical Sensors for Antioxidant/Oxidant Activity Monitoring)

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17 pages, 3872 KiB

Open AccessArticle

Glassy Carbon Electrode Modified with C/Au Nanostructured Materials for Simultaneous Determination of Hydroquinone and Catechol in Water Matrices

by Samuel Piña, Christian Candia-Onfray, Natalia Hassan, Paola Jara-Ulloa, David Contreras and Ricardo Salazar

Chemosensors 2021, 9(5), 88; https://doi.org/10.3390/chemosensors9050088 - 24 Apr 2021

Cited by 17 | Viewed by 3577

Abstract

The simultaneous determination of hydroquinone and catechol was conducted in aqueous and real samples by means of differential pulse voltammetry (DPV) using a glassy carbon electrode modified with Gold Nanoparticles (AuNP) and functionalized multiwalled carbon nanotubes by drop coating. A good response was [...] Read more.

The simultaneous determination of hydroquinone and catechol was conducted in aqueous and real samples by means of differential pulse voltammetry (DPV) using a glassy carbon electrode modified with Gold Nanoparticles (AuNP) and functionalized multiwalled carbon nanotubes by drop coating. A good response was obtained in the simultaneous determination of both isomers through standard addition to samples prepared with analytical grade water and multivariate calibration by partial least squares (PLS) in winery wastewater fortified with HQ and CT from 4.0 to 150.00 µM. A sensitivity of 0.154 µA µM⁻¹ and 0.107 µA µM⁻¹, and detection limits of 4.3 and 3.9 µM were found for hydroquinone and catechol, respectively. We verified the reliability of the developed method by simultaneously screening analytes in spiked tap water and industrial wastewater, achieving recoveries over 80%. In addition, this paper demonstrates the applicability of chemometric tools for the simultaneous quantification of both isomers in real matrices, obtaining prediction errors of lower than 10% in fortified wastewater. Full article

(This article belongs to the Special Issue Voltammperometric Sensors)

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19 pages, 31870 KiB

Open AccessArticle

Thiol-Amine Functionalized Decorated Carbon Nanotubes for Biomarker Gases Detection

by Atef Thamri, Hamdi Baccar, Juan Casanova-Chafer, Moataz Billeh Mejri, Eduard Llobet and Adnane Abdelghani

Chemosensors 2021, 9(5), 87; https://doi.org/10.3390/chemosensors9050087 - 23 Apr 2021

Cited by 4 | Viewed by 3615

Abstract

Thousands of gas molecules are expelled in exhaled breath, and some of them can reveal diseases and metabolomic disorders. For that reason, the development of fast, inexpensive, and reliable sensing devices has been attracting growing interest. Here, we present the development of different [...] Read more.

Thousands of gas molecules are expelled in exhaled breath, and some of them can reveal diseases and metabolomic disorders. For that reason, the development of fast, inexpensive, and reliable sensing devices has been attracting growing interest. Here, we present the development of different chemoresistors based on multi-walled carbon nanotubes (MWCNTs) decorated with platinum (MWCNT/Pt) and palladium (MWCNT/Pt) nanoparticles and also functionalized with a self-assembled monolayer (SAM) of 11-amino-1-undecanethiol (Thiol-amine). The nanocomposites developed are a proof-of-concept to detect some biomarker molecules. Specifically, the capability to identify and measure different concentrations of volatile organic compounds (VOCs), either aromatic (toluene and benzene) and non-aromatic (ethanol and methanol) was assessed. As a result, this paper reports the significant differences in sensing performance achieved according to the metal nanoparticle used, and the high sensitivity obtained when SAMs are grown on the sensitive film, acting as a receptor for biomarker vapours. Full article

(This article belongs to the Special Issue Chemical Sensors for Bio-Medical and Environmental Applications)

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10 pages, 1071 KiB

Open AccessArticle

Construction of a Highly Selective Membrane Sensor for the Determination of Cobalt (II) Ions

by Sabry Khalil and Mohamed El-Sharnouby

Chemosensors 2021, 9(5), 86; https://doi.org/10.3390/chemosensors9050086 - 21 Apr 2021

Cited by 9 | Viewed by 2139

Abstract

A highly Co (II) liquid ion-selective electrode depending on the reaction of cobalt ions with the reagent 2-(5-Bromo-2-pyridylazo)-5-[N-n-propyl-N-(3-sulfopropyl) amino] aniline is successfully fabricated. The characteristic slope (56.66 mV), the linear range response from 3.4 × 10⁻⁸ to 2.4 × 10⁻² molar, [...] Read more.

A highly Co (II) liquid ion-selective electrode depending on the reaction of cobalt ions with the reagent 2-(5-Bromo-2-pyridylazo)-5-[N-n-propyl-N-(3-sulfopropyl) amino] aniline is successfully fabricated. The characteristic slope (56.66 mV), the linear range response from 3.4 × 10⁻⁸ to 2.4 × 10⁻² molar, the detection limit (2.7 × 10⁻⁸) molar, the selectivity coefficient toward some metal ions, the time of response (10 s), lifetime (seven months), the pH effect on the sensor potential and the basic analytical parameters were studied. The sensor was used to estimate the concentration of cobalt ions in food products and pharmaceutical formulations. The obtained results of the developed sensor were statistically analyzed and compared with those of other different reported electrodes. Full article

(This article belongs to the Section Analytical Methods, Instrumentation and Miniaturization)

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