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Chemosensors, Volume 10, Issue 11 (November 2022) – 58 articles

Cover Story (view full-size image): GC and MS are widely used techniques in the analysis of complex mixtures due to their various advantages. However, data processing is often complex, time-consuming and requires a great deal of experience, which might be a serious drawback in certain areas. For these reasons, some authors have proposed the use of alternative data processing approaches, such as the TIC or TIMS, allowing these techniques to be treated as sensors where each retention time or ratio m/z acts as a sensor collecting total intensities. In this way, the main advantages associated with both techniques are maintained, but the outcomes from the analysis can be reached in a faster, simpler and almost automated way. In this review, the main features of the GC- and MS-based analysis methodologies and the ways in which to apply them are highlighted. View this paper
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26 pages, 2255 KiB  
Review
Electrochemical Sensing for Vitamins
by Yanting Yang, Ning Hu, Jinan Deng and Jun Yang
Chemosensors 2022, 10(11), 494; https://doi.org/10.3390/chemosensors10110494 - 21 Nov 2022
Cited by 6 | Viewed by 6848
Abstract
Vitamins are essential and necessary nutrients for the human body. Rapid and accurate quantification of their levels in various samples has attracted much attention. Compared with traditional analytical methods, electrochemical techniques, with the advantages of low cost, high sensitivity, flexible detection strategies, easy [...] Read more.
Vitamins are essential and necessary nutrients for the human body. Rapid and accurate quantification of their levels in various samples has attracted much attention. Compared with traditional analytical methods, electrochemical techniques, with the advantages of low cost, high sensitivity, flexible detection strategies, easy integration, and miniaturization, have gradually become the main tools in vitamin detection. In this paper, the advance of electrochemical sensing of vitamins in recent years is reviewed. Firstly, the basics of different vitamins are briefly introduced. Then, the commonly-used electrodes and electrochemical methods for vitamin electrochemical detection, as well as the specific implementation strategy and performance, are described in detail. The development of miniaturization devices, especially microfluidic and microsensor devices, is also presented. Finally, the challenges faced by the electrochemical detection of vitamins are discussed, and future development is prospected. Full article
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25 pages, 1785 KiB  
Review
Luminescent Analysis of ATP: Modern Objects and Processes for Sensing
by Elena Efremenko, Olga Senko, Nikolay Stepanov, Olga Maslova, Galina Yu. Lomakina and Natalia Ugarova
Chemosensors 2022, 10(11), 493; https://doi.org/10.3390/chemosensors10110493 - 21 Nov 2022
Cited by 7 | Viewed by 2265
Abstract
Bioluminescent analysis of adenosine triphosphate (ATP) concentrations is now acquiring new applications in the form of objects and processes in which it can be effectively used for sensing. A quick analysis of biological objects and systems for which the level of ATP concentrations [...] Read more.
Bioluminescent analysis of adenosine triphosphate (ATP) concentrations is now acquiring new applications in the form of objects and processes in which it can be effectively used for sensing. A quick analysis of biological objects and systems for which the level of ATP concentrations is one of the main parameters, and a forecast of the development of various situations in such biosystems under industrial production conditions or the ecological state of the environment, confirmed by various results of analytical control of other parameters, turns out to be simple and effective. Sanitary control, quality control of purified water, microbial analysis in the food industry, maintenance of drugs and estimation of their quality, and monitoring of the metabolic state of biocatalysts used in various biotechnological processes are between the main trends of recent applications of bioluminescent ATP-assay. Additionally, the new areas of ATP sensing are developed, and the following topics are their creation of synthetic microbial consortia, their introduction as new biocatalysts to biodegradation of pesticides, suppression of methane accumulation in model urban land fields, control of dangerous development of biocorrosive processes, design of chemical-biocatalytic hybrid processes, creation of effective antimicrobial dressing and protective tissue materials, etc. These aspects are the subject of this review. Full article
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8 pages, 1734 KiB  
Article
Mechanism of Fast NO Response in a WO3-Nanorod-Based Gas Sensor
by Giacometta Mineo, Kaveh Moulaee, Giovanni Neri, Salvo Mirabella and Elena Bruno
Chemosensors 2022, 10(11), 492; https://doi.org/10.3390/chemosensors10110492 - 20 Nov 2022
Cited by 4 | Viewed by 1694
Abstract
The development of fast and reliable gas sensors is a pressing and growing problem for environmental monitoring due to the presence of pollutants in the atmosphere. Among all gases, particular attention is devoted to NO, which can cause serious health problems. WO3 [...] Read more.
The development of fast and reliable gas sensors is a pressing and growing problem for environmental monitoring due to the presence of pollutants in the atmosphere. Among all gases, particular attention is devoted to NO, which can cause serious health problems. WO3 nanorods represent promising candidates for this purpose due to their high electrical stability and low cost of production. Here, the hydrothermal synthesis of WO3 nanorods is reported, in addition to the realization of a chemo-resistive NO sensor. NO-sensing tests were performed at different temperatures (250–400 °C) and under different gas concentrations (250–2500 ppm), and NO response and recovery curves were also modeled by using the Langmuir adsorption theory by highlighting the NO-sensing mechanism of the WO3 nanorods. An interaction occurred at the surface between NO and the adsorbed oxygen ions, thus clarifying the NO-reducing behavior. The fast response and recovery times open the route for the development of fast NO sensors based on WO3. Full article
(This article belongs to the Special Issue Room Temperature Detection and Sensing Technologies)
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13 pages, 1123 KiB  
Article
Screening of Chemical Composition, Antimicrobial and Antioxidant Activities of Essential Oil and Volatile Fraction from Olive Mill Wastewater
by Chahinez Ait Si Said, Nacera Riad, Mohamed Reda Zahi, Smain Sabour, Salah Akkal, Wissam Zam, Ouassila Touafek and Mohamed El Hattab
Chemosensors 2022, 10(11), 491; https://doi.org/10.3390/chemosensors10110491 - 19 Nov 2022
Cited by 5 | Viewed by 1692
Abstract
Oil mill wastewater is the main by-product of the olive oil industry resulting mainly from the treatment and pressing of olives in mills. It is a rich source of nutrients and phytochemicals with a wide spectrum of biological properties. The present study focuses [...] Read more.
Oil mill wastewater is the main by-product of the olive oil industry resulting mainly from the treatment and pressing of olives in mills. It is a rich source of nutrients and phytochemicals with a wide spectrum of biological properties. The present study focuses on the chemical analysis and evaluation of the antimicrobial and antioxidant activity of the essential oil (EO) and the volatile fraction (VF) obtained, respectively, by hydrodistillation. Chemical analysis by gas chromatography coupled to mass spectrometry (GC/MS) and a flame ionisation detector (GC/FID) revealed the predominance of phenolic compounds (25.71%, 60.36%) and fatty acids (62.37%, 38.25%) for the VF and EO, respectively. It was also shown that the main compounds were oleic acid (24.9%) for the VF and 4-ethylphenol (28.5%) for the EO. The results of the antimicrobial activity in terms of MIC values against twelve microorganisms showed that, overall, the VF was more active than the EO. The antioxidant activity of the VF and EO was evaluated using the DPPH assay and expressed as half-maximal inhibitory concentration (IC50), where the EO (218 μg/mL) showed better antioxidant activity than the VF (244 μg/mL). The results also revealed that the antimicrobial activity and antioxidant activity values for both oils were significantly lower than the standards used. Full article
(This article belongs to the Special Issue GC, MS and GC-MS Analytical Methods: Opportunities and Challenges)
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11 pages, 4556 KiB  
Communication
Detection of Carbon Content from Pulverized Coal Using LIBS Coupled with DSC-PLS Method
by Congrong Guan, Tianyu Wu, Jiwen Chen and Ming Li
Chemosensors 2022, 10(11), 490; https://doi.org/10.3390/chemosensors10110490 - 17 Nov 2022
Cited by 1 | Viewed by 1674
Abstract
The dust from pulverized coal weakens the acquired signal and increases the analysis difficulty for the quantitative analysis of the carbon content of pulverized coal when using laser-induced breakdown spectroscopy (LIBS). Moreover, there is a serious matrix effect and a self-absorption phenomenon. To [...] Read more.
The dust from pulverized coal weakens the acquired signal and increases the analysis difficulty for the quantitative analysis of the carbon content of pulverized coal when using laser-induced breakdown spectroscopy (LIBS). Moreover, there is a serious matrix effect and a self-absorption phenomenon. To improve the analysis accuracy, the DSC-PLS (double spectral correction-partial-least-squares) method was proposed to predict the carbon content of pulverized coal. Initially, the LIBS signal was corrected twice using P-operation-assisted adaptive iterative-weighted penalized-least-squares (P-airPLS), plasma temperature compensation, and spectral normalization algorithms. The goodness of fit of the carbon element was improved from nonlinearity to above 0.948. The modified signal was then used to establish DCS-PLS models for predicting unknown samples. In comparison to the conventional PLS model, the DSC-PLS method proposed in this paper significantly improves the ability to predict carbon content. The prediction error of the developed method was dropped from an average of 4.66% to about 0.41%, with the goodness of fit R2 of around 0.991. Full article
(This article belongs to the Special Issue Chemometrics for Analytical Chemistry)
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36 pages, 10219 KiB  
Article
Optimization of Aluminum Dopant Amalgamation Immersion Time on Structural, Electrical, and Humidity-Sensing Attributes of Pristine ZnO for Flexible Humidity Sensor Application
by A Shamsul Rahimi A Subki, Mohamad Hafiz Mamat, Musa Mohamed Zahidi, Mohd Hanapiah Abdullah, I. B. Shameem Banu, Nagamalai Vasimalai, Mohd Khairul Ahmad, Nafarizal Nayan, Suriani Abu Bakar, Azmi Mohamed, Muhammad Danang Birowosuto and Mohamad Rusop Mahmood
Chemosensors 2022, 10(11), 489; https://doi.org/10.3390/chemosensors10110489 - 17 Nov 2022
Cited by 8 | Viewed by 2885
Abstract
This study synthesized pristine and aluminum (Al)-doped zinc oxide (Al:ZnO) nanostructures through a simplistic low-temperature ultrasonicated solution immersion method. Al:ZnO nanostructures were synthesized as a sensing material using different immersion times varying from two to five hours. The Al:ZnO nanostructured-based flexible humidity sensor [...] Read more.
This study synthesized pristine and aluminum (Al)-doped zinc oxide (Al:ZnO) nanostructures through a simplistic low-temperature ultrasonicated solution immersion method. Al:ZnO nanostructures were synthesized as a sensing material using different immersion times varying from two to five hours. The Al:ZnO nanostructured-based flexible humidity sensor was fabricated by employing cellulose filter paper as a substrate and transparent paper glue as a binder through a simplistic brush printing technique. XRD, FESEM, HRTEM, EDS, XPS, a two-probe I–V measurement system, and a humidity measurement system were employed to investigate the structural, morphological, chemical, electrical, and humidity-sensing properties of the pristine ZnO and Al:ZnO nanostructures. The structural and morphological analysis confirmed that Al cations successfully occupied the Zn lattice or integrated into interstitial sites of the ZnO lattice matrix. Humidity-sensing performance analysis indicated that the resistance of the Al:ZnO nanostructure samples decreased almost linearly as the humidity level increased, leading to better sensitivity and sensing response. The Al:ZnO-4 h nanostructured-based flexible humidity sensor had a maximum sensing response and demonstrated the highest sensitivity towards humidity changes, which was noticeably superior to the other tested samples. Finally, this study explained the Al:ZnO nanostructures-based flexible humidity sensor sensing mechanism in terms of chemical adsorption, physical adsorption, and capillary condensation mechanisms. Full article
(This article belongs to the Collection Sustainable Metal Oxide Materials for Sensing Applications)
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15 pages, 3338 KiB  
Article
Nanostructured Diamond Composites for Multifunctional Sensing Applications
by Eric Y. Li, Elluz Pacheco, Andrew F. Zhou and Peter X. Feng
Chemosensors 2022, 10(11), 488; https://doi.org/10.3390/chemosensors10110488 - 17 Nov 2022
Cited by 3 | Viewed by 1371
Abstract
We report studies of multifunctional, nanostructured diamond composites that were fabricated using chemical vapor deposition (CVD) techniques. Grain sizes from micrometer, to submicron, nano, and ultrananocrystalline diamond (UNCD) were controlled by varying CH4, hydrogen, and argon gas concentrations during the syntheses. [...] Read more.
We report studies of multifunctional, nanostructured diamond composites that were fabricated using chemical vapor deposition (CVD) techniques. Grain sizes from micrometer, to submicron, nano, and ultrananocrystalline diamond (UNCD) were controlled by varying CH4, hydrogen, and argon gas concentrations during the syntheses. Scanning electron microscopy (SEM) and Raman scattering spectroscopy were used to investigate the morphologies, composites, and crystallinities of the films. Four multifunctional sensor prototypes were designed, fabricated, and tested, based on the four diamond materials of different grain sizes. The responses of the four prototypes to either pollution gas or UV light illumination were systematically investigated at different operating temperatures. Experimental data indicated the obtained UNCD composite from the low-cost simple CVD fabrication technique appeared to have very good sensitivities when exposed to low concentrations of H2 or NH3 gas with a decent response and fast recovery time. Furthermore, highly induced photocurrents from both microdiamond- and UNCD-based prototypes to deep UV illumination were also demonstrated, with responsivities up to 2750 mA/W and 550 mA/W at 250 nm wavelength, respectively. Overall, the fabricated UNCD prototypes displayed a good balance in performance for multifunctional sensor applications in terms of responsivity, stability, and repeatability. Full article
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14 pages, 5307 KiB  
Article
Detection of Azo Dyes Using Carbon Dots from Olive Mill Wastes
by Diogo A. Sousa, Mário N. Berberan-Santos and José V. Prata
Chemosensors 2022, 10(11), 487; https://doi.org/10.3390/chemosensors10110487 - 16 Nov 2022
Cited by 3 | Viewed by 1702
Abstract
Azo dyes are widely spread in our day life, being heavily used in cosmetics, healthcare products, textile industries, and as artificial food colorants. This intense industrial activity, which inherently includes their own production, inexorably leads to uncontrolled release of dyes into the environment. [...] Read more.
Azo dyes are widely spread in our day life, being heavily used in cosmetics, healthcare products, textile industries, and as artificial food colorants. This intense industrial activity, which inherently includes their own production, inexorably leads to uncontrolled release of dyes into the environment. As emerging pollutants, their detection, particularly in water systems, is a priority. Herein, a fluorescence-based method was employed for the sensitive and selective detection of anionic and neutral azo dyes. Carbon dots (CDs) synthesized from wet pomace (WP), an abundant semi-solid waste of olive mills, were used as probes. An outstanding capability for detection of azo dyes methyl orange (MO) and methyl red (MR) in aqueous solutions was disclosed, which reached a limit of detection (LOD) of 151 ppb for MO. The selectivity of WP-CDs for the anionic azo dye (MO) was established through competitive experiments with other dyes, either anionic (indigo carmine) or cationic (fuchsin, methylene blue, and rhodamine 6G); perchlorate salts of transition metal cations (Cu(II), Co(II), Fe(II), Fe(III), Hg(II), and Pb(II)); and sodium salts of common anions (NO3, CO32−, Cl, and SO42−). Evidence has been collected that supports static quenching as the main transduction event underlying the observed quenching of the probe’s fluorescence, combined with a dynamic resonance energy transfer (RET) mechanism at high MO concentrations. Full article
(This article belongs to the Special Issue Chemosensors for Ion Detection)
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19 pages, 3547 KiB  
Article
Electronic Nose Analysis and Statistical Methods for Investigating Volatile Organic Compounds and Yield of Mint Essential Oils Obtained by Hydrodistillation
by Sepideh Zorpeykar, Esmaeil Mirzaee-Ghaleh, Hamed Karami, Zeynab Ramedani and Alphus Dan Wilson
Chemosensors 2022, 10(11), 486; https://doi.org/10.3390/chemosensors10110486 - 16 Nov 2022
Cited by 8 | Viewed by 1923
Abstract
A major problem associated with the development of medicinal plant products is the lack of quick, easy, and inexpensive methods to assess and monitor product quality. Essential oils are natural plant-derived volatile substances used worldwide for numerous applications. The important uses of these [...] Read more.
A major problem associated with the development of medicinal plant products is the lack of quick, easy, and inexpensive methods to assess and monitor product quality. Essential oils are natural plant-derived volatile substances used worldwide for numerous applications. The important uses of these valuable products often induce producers to create fraudulent or lower quality products. As a result, consumers place a high value on authentic and certified products. Mint is valued for essential oil used in the food, pharmaceutical, cosmetic, and health industries. This study investigated the use of an experimental electronic nose (e-nose) for the detection of steam-distilled essential oils. The e-nose was used to evaluate and analyze VOC emissions from essential oil (EO) and distilled water extracts (DWEs) obtained from mint plants of different ages and for leaves dried in the shade or in the sun prior to hydrodistillation. Principal component analysis (PCA), linear discriminant analysis (LDA), and artificial neural networks (ANN) were performed on electrical signals generated from electronic nose sensors for the classification of VOC emissions. More accurate discriminations were obtained for DWEs sample VOCs than for EO VOCs. The electronic nose proved to be a reliable and fast tool for identifying plant EO. The age of plants had no statistically significant effect on the EO concentration extracted from mint leaves. Full article
(This article belongs to the Special Issue Chemometrics for Analytical Chemistry)
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8 pages, 3313 KiB  
Communication
Graphdiyne-Templated Platinum Nanoparticles as a Novel Platform for the Electrochemical Determination of Bisphenol AF
by Yu Zhang, Zhi Xia, Guofeng Gui, Ping Zhang, Qianzhu Li and Lifen Meng
Chemosensors 2022, 10(11), 485; https://doi.org/10.3390/chemosensors10110485 - 16 Nov 2022
Cited by 2 | Viewed by 1178
Abstract
This work constructed an ultrasensitive electrochemical bisphenol AF (BPAF) sensor using ultra-stable graphdiyne-templated platinum nanoparticles (PtNPs@GDY) as a sensing platform. PtNPs@GDY nanocomposite was synthesized by a chemical reduction method, and the preparation process was simple and rapid. GDY, with its natural porous structure, [...] Read more.
This work constructed an ultrasensitive electrochemical bisphenol AF (BPAF) sensor using ultra-stable graphdiyne-templated platinum nanoparticles (PtNPs@GDY) as a sensing platform. PtNPs@GDY nanocomposite was synthesized by a chemical reduction method, and the preparation process was simple and rapid. GDY, with its natural porous structure, was used as substrate to stabilize PtNPs. Due to the high adsorption ability of GDY, it can prevent PtNPs from aggregation and inactivation. Transmission electron microscopy (TEM), high-resolution TEM (HRTEM) and Energy-dispersive X-ray spectroscopy (EDS) were used to characterize the microstructure and morphologies of the materials. Cyclic voltammetry (CV), Electrochemical impedance spectroscopy (EIS) and differential pulse voltammetry (DPV) were employed to investigate the electrochemical properties of the material and the performance of the sensor. At an optimized condition, the sensor exhibited excellent catalytic activities towards BPAF. The linear ranges were from 0.4 to 15.4 μM and 35.4 to 775.4 μM. The limit of detection was 0.09 μM. In addition, the electrochemical sensor showed good reproducibility, stability and anti-interference. Full article
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30 pages, 11484 KiB  
Review
Triboelectric Nanogenerators in Sustainable Chemical Sensors
by Qiliang Zhu, Xia Cao and Ning Wang
Chemosensors 2022, 10(11), 484; https://doi.org/10.3390/chemosensors10110484 - 15 Nov 2022
Cited by 8 | Viewed by 2712
Abstract
The rapid development of sensing technology has created an urgent need for chemical sensor systems that can be rationally integrated into efficient, sustainable, and wearable electronic systems. In this case, the triboelectric nanogenerator (TENG) is expected to be a major impetus to such [...] Read more.
The rapid development of sensing technology has created an urgent need for chemical sensor systems that can be rationally integrated into efficient, sustainable, and wearable electronic systems. In this case, the triboelectric nanogenerator (TENG) is expected to be a major impetus to such innovation because it can not only power the sensor by scavenging mechanical energies and transforming them into electricity but also act as the chemical sensor itself due to its intrinsic sensitivity towards the chemical reaction that occurs at the triboelectric interface. In this review, recent research achievements of chemical sensors that are based on TENGs are comprehensively reviewed according to the role of TENGs in the system, that is, pure power supplies or self-powered active chemical sensors. Focus is put on discussing the design criteria and practical applications of the TENG-based active sensors in different fields, which is unfolded with a classification that includes biosensors, gas sensors, and ion sensors. The materials selection, working mechanism, and design strategies of TENG-based active chemical sensor systems (CSSs) are also discussed, ending with a concise illustration of the key challenges and possible corresponding solutions. We hope this review will bring inspiration for the creation and development of TENG-based chemical sensors with higher sensitivity, simpler structure, and enhanced reliability. Full article
(This article belongs to the Special Issue Latest Advances in Nanobiosensors: Novel Materials and Applications)
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15 pages, 6027 KiB  
Article
Optimizing the Heavy Metal Ion Sensing Properties of Functionalized Silver Nanoparticles: The Role of Surface Coating Density
by Andrea Rossi, Massimiliano Cuccioloni, Lisa Rita Magnaghi, Raffaela Biesuz, Marco Zannotti, Laura Petetta, Mauro Angeletti and Rita Giovannetti
Chemosensors 2022, 10(11), 483; https://doi.org/10.3390/chemosensors10110483 - 15 Nov 2022
Cited by 5 | Viewed by 2025
Abstract
We present a colorimetric sensor based on functionalized silver nanoparticles for the detection of metal ions in aqueous solutions. The interaction between the target metal ion and the functionalizing agent triggers the aggregation of these nanoparticles, and the consequent change in optical properties [...] Read more.
We present a colorimetric sensor based on functionalized silver nanoparticles for the detection of metal ions in aqueous solutions. The interaction between the target metal ion and the functionalizing agent triggers the aggregation of these nanoparticles, and the consequent change in optical properties allows the detection/quantification of the analyte. In detail, this work describes the synthesis of AgNPs by a chemical reduction method, and the production of mercaptoundecanoic acid functionalized NPs with different surface densities (multi-, full-, and two partial layers). UV-Vis spectroscopy was used to monitor the functionalization processes, and to investigate the aggregation behavior of each AgNPs@11MUA sensor upon titration with the metal ions of interest, namely Ni2+, Zn2+, Co2+, Cd2+, Mn2+, and Cu2+. The resulting UV-Vis raw data obtained for each layer density were submitted to principal component analysis to dissect the role of the metal ions in NP aggregation and in establishing the sensitivity and selectivity of the AgNPs@11MUA sensor. Interestingly, we observed an increase in sensor sensitivity and selectivity at a lower density of the functionalizing agent on the AgNPs’ surface, which results in characteristic colors of the NP suspension upon titration with each metal ion. Full article
(This article belongs to the Special Issue Chemosensors for Ion Detection)
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18 pages, 973 KiB  
Review
Recent Advances in Gas Sensing Technology Using Non-Oxide II-VI Semiconductors CdS, CdSe, and CdTe
by Masanori Ando, Hideya Kawasaki, Satoru Tamura, Yoshikazu Haramoto and Yasushi Shigeri
Chemosensors 2022, 10(11), 482; https://doi.org/10.3390/chemosensors10110482 - 15 Nov 2022
Cited by 6 | Viewed by 2287
Abstract
In recent years, there has been an increasing need and demand for gas sensors to detect hazardous gases in the atmosphere, as they are indispensable for environmental monitoring. Typical hazardous gas sensors that have been widely put to practical use include conductometric gas [...] Read more.
In recent years, there has been an increasing need and demand for gas sensors to detect hazardous gases in the atmosphere, as they are indispensable for environmental monitoring. Typical hazardous gas sensors that have been widely put to practical use include conductometric gas sensors, such as semiconductor gas sensors that use the change in electrical resistance of metal oxide semiconductors, catalytic combustion gas sensors, and electrochemical gas sensors. However, there is a growing demand for gas sensors that perform better and more safely, while also being smaller, lighter, less energy-demanding, and less costly. Therefore, new gas sensor materials are being explored, as well as optical gas sensor technology that expresses gas detection not electrically but optically. Cadmium sulfide (CdS), cadmium selenide (CdSe), and cadmium telluride (CdTe) are typical group II-VI non-oxide semiconductors that have been used as, for example, electronic materials. Recently, they have attracted attention as new gas sensor materials. In this article, recent advances in conductometric and optical gas sensing technologies using CdS, CdSe, and CdTe are reviewed. Full article
(This article belongs to the Special Issue Gas Sensing beyond MOX Semiconductors)
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14 pages, 4290 KiB  
Article
Porphyrin Hetero-Trimer Involving a Hydrophilic and a Hydrophobic Structure with Application in the Fluorescent Detection of Toluidine Blue
by Anca Lascu, Camelia Epuran, Ion Fratilescu, Mihaela Birdeanu, Liliana Halip and Eugenia Fagadar-Cosma
Chemosensors 2022, 10(11), 481; https://doi.org/10.3390/chemosensors10110481 - 15 Nov 2022
Viewed by 1527
Abstract
The combination of a metallated porphyrin, Pt(II)-5,10,15,20-tetrakis-(4-allyloxyphenyl)-porphyrin (Pt-allyloxyPP), and a water-soluble porphyrin, 5,10,15,20-tetrakis(4-sulfonatophenyl)-porphyrin (TSPP), leads to the formation of a porphyrin hetero-trimer. The hetero-trimer, consisting of two TSPP molecules linked via oxygen atoms axially to the platinum atom in the Pt-allyloxyPP molecule, was [...] Read more.
The combination of a metallated porphyrin, Pt(II)-5,10,15,20-tetrakis-(4-allyloxyphenyl)-porphyrin (Pt-allyloxyPP), and a water-soluble porphyrin, 5,10,15,20-tetrakis(4-sulfonatophenyl)-porphyrin (TSPP), leads to the formation of a porphyrin hetero-trimer. The hetero-trimer, consisting of two TSPP molecules linked via oxygen atoms axially to the platinum atom in the Pt-allyloxyPP molecule, was characterized by UV–Vis, FT-IR, fluorescence, and 1H-NMR spectroscopy, and the proposed structure was confirmed. The new porphyrin hetero-trimer offers both the advantage of enhanced fluorescence and the presence of multiple sites for the detection of toluidine blue, due to its high affinity for acidic binding sites. This work brings attention to the purposely designed fluorescent sensor for toluidine blue, in the biologically relevant concentration domain of 1.9 × 10−6–6.39 × 10−5 M, with a very good accuracy. Full article
(This article belongs to the Section Materials for Chemical Sensing)
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11 pages, 3017 KiB  
Article
Prediction of Diamene-Based Chemosensors
by Danil W. Boukhvalov and Vladimir Yu. Osipov
Chemosensors 2022, 10(11), 480; https://doi.org/10.3390/chemosensors10110480 - 15 Nov 2022
Cited by 4 | Viewed by 1662
Abstract
This paper presents the results of systematic studies of the atomic structure of the layered bulk, bilayer, and monolayer of diamene (a two-dimensional diamond monolayer recently synthesized by various methods) functionalized with fluorine and hydroxyl groups with the chemical formulas C2F [...] Read more.
This paper presents the results of systematic studies of the atomic structure of the layered bulk, bilayer, and monolayer of diamene (a two-dimensional diamond monolayer recently synthesized by various methods) functionalized with fluorine and hydroxyl groups with the chemical formulas C2F and C2OH. The results of our calculations show that both types of diamene under discussion have a wide optical gap corresponding to the absorption of light in the UV spectral range. The formation of a boundary between these two types of diamene layers leads to a significant decrease in the band gap. Therefore, this layered material, with an interface between fluorinated and hydroxylated diamenes (C2F/C2OH structures), can be considered a suitable material for converting UV radiation into visible light in the orange-yellow part of the spectrum. The adsorption of acetone or water on the C2F/C2OH structures results in visible changes in the band gap. The effect on photoemission is different for different detected analytes. The presence of formaldehyde in water ensures the appearance of distinct peaks in the absorption spectra of structures based on C2F/C2OH. Our simulation results suggest that the simulated C2F/C2OH structures can be used as chemically stable, lightweight materials composed of common elements for a highly selective chemical sensor in liquid and air. Full article
(This article belongs to the Special Issue Gas Sensors for Monitoring Environmental Changes)
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13 pages, 2671 KiB  
Article
Phthalocyanine-Carbon Nanotube Hybrid Materials: Mechanism of Sensor Response to Ammonia from Quantum-Chemical Point of View
by Pavel Krasnov, Victoria Ivanova, Darya Klyamer, Aleksandr Fedorov and Tamara Basova
Chemosensors 2022, 10(11), 479; https://doi.org/10.3390/chemosensors10110479 - 14 Nov 2022
Cited by 2 | Viewed by 1854
Abstract
Quantum chemical calculations of the geometric and electronic structure of periodic hybrid compounds representing carbon nanotubes (10,0) with zinc phthalocyanine molecules ZnPc-xpy (x = 0, 1, 2, 4) on their surface and their interaction with ammonia were carried out to explain [...] Read more.
Quantum chemical calculations of the geometric and electronic structure of periodic hybrid compounds representing carbon nanotubes (10,0) with zinc phthalocyanine molecules ZnPc-xpy (x = 0, 1, 2, 4) on their surface and their interaction with ammonia were carried out to explain the dependence of the sensor response of the hybrid materials to ammonia on the number of substituents in the ZnPc-xpy macrocycle and to clarify the nature of the interaction between ammonia and phthalocyanine molecules. It was found that the key feature of these materials, which determines their sensor response toward ammonia, is the presence of an impurity band in the band gap of a carbon nanotube, formed by the orbitals of macrocycle atoms. When ammonia adsorbs through the formation of hydrogen bonds with the side atoms of phthalocyanine, the energy of this impurity band decreases. As a consequence, the electron population of the conduction band and, accordingly, the electrical conductivity of the hybrid materials become lower. Moreover, with an increase in the number of oxypyrene substituents in ZnPc-xpy, the interaction energy of ammonia increases and, as a result, the decrease in the energy of the impurity band becomes higher. These facts may explain recent experimental measurements of the parameters of the sensor response of similar hybrid materials to ammonia, where, in particular, it was shown that the sensor response is reversible, and its value increases with an increase in the number of oxypyrene substituents in the phthalocyanine macrocycle. Full article
(This article belongs to the Special Issue Carbon Nanomaterials and Related Materials for Sensing Applications)
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14 pages, 4327 KiB  
Article
Development and Field Validation of Low-Cost Metal Oxide Nanosensors for Tropospheric Ozone Monitoring in Rural Areas
by Jaime Gómez-Suárez, Patricia Arroyo, María Cerrato-Álvarez, Esther Hontañón, Sergio Masa, Philippe Menini, Lionel Presmanes, Raimundo Alfonso, Eduardo Pinilla-Gil and Jesús Lozano
Chemosensors 2022, 10(11), 478; https://doi.org/10.3390/chemosensors10110478 - 14 Nov 2022
Cited by 3 | Viewed by 1584
Abstract
This work describes the technical features and the performance of two different types of metal-oxide semiconductor sensors, based on ZnO:Ga thin films and SnO2-G nanofibrous layers, for tropospheric ozone monitoring in ambient air. These nanostructures were tested and compared with commercial [...] Read more.
This work describes the technical features and the performance of two different types of metal-oxide semiconductor sensors, based on ZnO:Ga thin films and SnO2-G nanofibrous layers, for tropospheric ozone monitoring in ambient air. These nanostructures were tested and compared with commercial metal-oxide semiconductor sensors under controlled laboratory conditions and in a field campaign during summer 2021 in Monfragüe National Park (western Spain). The paper also details the design of the electronic device developed for this purpose. A machine learning algorithm based on Support Vector Regression (SVR) allowed the conversion of the resistive values into ozone concentration, which was evaluated afterward. The results showed that the manufactured sensors performed similarly to the commercial sensors in terms of R2 (0.94 and 0.95) and RMSE (5.21 and 4.83 μg∙m−3). Moreover, a novel uncertainty calculation based on European guides for air quality sensor testing was conducted, in which the manufactured sensors outperformed the commercial ones. Full article
(This article belongs to the Special Issue Chemosensors in Biological Challenges)
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14 pages, 3396 KiB  
Article
Rational Design of Ratiometric Fluorescent Probe for Zn2+ Imaging under Oxidative Stress in Cells
by Yaheng Li, Shankun Yao, Hongbao Fang, Weijiang He, Yuncong Chen and Zijian Guo
Chemosensors 2022, 10(11), 477; https://doi.org/10.3390/chemosensors10110477 - 13 Nov 2022
Cited by 5 | Viewed by 1643
Abstract
Zn2+ is a vital ion for most of the physiological processes in the human body, and it usually has a mutual effect with oxidative stress that often occurs in pathological tissues. Detecting fluctuation of Zn2+ level in cells undergoing oxidative stress [...] Read more.
Zn2+ is a vital ion for most of the physiological processes in the human body, and it usually has a mutual effect with oxidative stress that often occurs in pathological tissues. Detecting fluctuation of Zn2+ level in cells undergoing oxidative stress could be beneficial to understanding the relationship between them. Herein, a ratiometric fluorescent Zn2+ probe was rationally designed. The wavelength corresponding to the maximum fluorescence intensity bathometrically shifted from 620 nm to 650 nm after coordinating with Zn2+. The intensity ratio of two fluorescence channels changed significantly in cells treated by oxidative stress inducers. It was shown from the results that the labile zinc level was generally elevated under oxidative stress stimulated by various inducers. Full article
(This article belongs to the Special Issue Chemosensors for Ion Detection)
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16 pages, 2965 KiB  
Article
Energy-Efficient Chemiresistive Sensor Array Based on SWCNT Networks, WO3 Nanochannels and SWCNT-Pt Heterojunctions for NH3 Detection against the Background Humidity
by Alexey V. Romashkin, Andrey V. Lashkov, Victor V. Sysoev, Nikolay S. Struchkov, Evgeny V. Alexandrov and Denis D. Levin
Chemosensors 2022, 10(11), 476; https://doi.org/10.3390/chemosensors10110476 - 12 Nov 2022
Cited by 1 | Viewed by 1447
Abstract
Recently, promising results have been achieved in improving the sensitivity to ammonia in gas sensors through the use of structures composed of heterojunctions or nanochannels. However, their sensitivity is highly dependent on the background humidity under air conditions. The sensor structures which could [...] Read more.
Recently, promising results have been achieved in improving the sensitivity to ammonia in gas sensors through the use of structures composed of heterojunctions or nanochannels. However, their sensitivity is highly dependent on the background humidity under air conditions. The sensor structures which could ensure selective ammonia detection with a low detection limit, despite interference from changing background humidity, remain highly demanded. In this work, we consider sensing units containing (i) nanochannels formed by a continuous tungsten oxide nanolayer to appear in contact between single-walled carbon nanotubes (SWCNTs) and a Pt sublayer and (ii) SWCNT-Pt junctions in frames of mass-scale microelectronic technologies. SWCNTs were deposited by spray-coating on a thin WO3/Pt/W sublayer formed by a photolithographic pattern to be accompanied by satellite samples with just SWCNTs for reference purposes. We elucidate the specific differences that appeared in the response of sensors based on SWCNT-Pt junctions and WO3 nanochannels relative to satellite SWCNT samples with a similar SWCNT network density. Particularly, while a similar response to NH3 vapors mixed with dry air is observed for each sensor type, the response to NH3 is reduced significantly in the presence of background humidity, of 45 rel.%, especially in the case of WO3 nanochannel structures even at room temperature. A multisensor array based on the four various sensing structures involving SWCNT-Pt junctions, WO3 nanochannels, and their satellite-only-SWCNT ones allowed us to determine a correct ammonia concentration via utilizing the linear discriminant analysis despite the presence of background air humidity. Thus, such an energy-efficient multisensor system can be used for environmental monitoring of ammonia content, health monitoring, and other applications. Full article
(This article belongs to the Special Issue Gas Sensors for Monitoring Environmental Changes)
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19 pages, 2008 KiB  
Article
Applying Two-Dimensional Correlation Spectroscopy and Principal Component Analysis to Understand How Temperature Affects the Neptunium(V) Absorption Spectrum
by Luke R. Sadergaski and Kyle Morgan
Chemosensors 2022, 10(11), 475; https://doi.org/10.3390/chemosensors10110475 - 12 Nov 2022
Cited by 5 | Viewed by 1663
Abstract
The visible-near infrared (Vis-NIR) electronic absorption spectrum of neptunium(V) (NpO2+) comprises numerous f-f electronic transitions with mostly undocumented temperature dependencies. The effect of temperature on the absorption spectrum of the pentavalent neptunyl dioxocation (NpO2+) is an important [...] Read more.
The visible-near infrared (Vis-NIR) electronic absorption spectrum of neptunium(V) (NpO2+) comprises numerous f-f electronic transitions with mostly undocumented temperature dependencies. The effect of temperature on the absorption spectrum of the pentavalent neptunyl dioxocation (NpO2+) is an important factor to consider with spectrophotometric applications but has often been overlooked. Optical Vis-NIR absorption spectra (400–1700 nm) of Np(V) (0.017–0.89 M) in 1 M nitric acid were evaluated with varying temperatures (T = 10–80 °C). The intensity, position, and overall shape of the bands were sensitive to interactions with the solvent and coordination environment. Numerous temperature-induced isosbestic points were identified resulting from dynamic, overlapping peak shifts. Spectral variations were characterized using principal component analysis (PCA) and 2D correlation spectroscopy (COS). 2D-COS revealed that the absorption band near 1095 nm likely consists of two bands centered near 1087 and 1096 nm, which cannot be explained by current computational methods. 2D-COS analysis also provided an unambiguous assignment of unresolved peaks in the visible region for comparison with computational predictions. PCA was used to identify nonlinearity in the spectral response at elevated Np(V) concentrations ≥ 0.5 M. This unique experimental data and interpretation will foster a deeper understanding of the absorption spectra for complex actinyl ions. Full article
(This article belongs to the Special Issue Chemometrics for Analytical Chemistry)
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18 pages, 7899 KiB  
Article
Machine Learning-Based Multi-Level Fusion Framework for a Hybrid Voltammetric and Impedimetric Metal Ions Electronic Tongue
by Tianqi Lu, Ammar Al-Hamry, Junfeng Hao, Yang Liu, Yunze Qu and Olfa Kanoun
Chemosensors 2022, 10(11), 474; https://doi.org/10.3390/chemosensors10110474 - 12 Nov 2022
Cited by 1 | Viewed by 1902
Abstract
Electronic tongues and artificial gustation for crucial analytes in the environment, such as metal ions, are becoming increasingly important. In this contribution, we propose a multi-level fusion framework for a hybrid impedimetric and voltammetric electronic tongue to enhance the accuracy of K+ [...] Read more.
Electronic tongues and artificial gustation for crucial analytes in the environment, such as metal ions, are becoming increasingly important. In this contribution, we propose a multi-level fusion framework for a hybrid impedimetric and voltammetric electronic tongue to enhance the accuracy of K+, Mg2+, and Ca2+ detection in an extensive concentration range (100.0 nM–1.0 mM). The proposed framework extracts electrochemical-based features and separately fuses, in the first step, impedimetric features, which are characteristic points and fixed frequency features, and the voltammetric features, which are current and potential features, for data reduction by LDA and classification by kNN. Then, in a second step, a decision fusion is carried out to combine the results for both measurement methods based on Dempster–Shafer (DS) evidence theory. The classification results reach an accuracy of 80.98% and 81.48% for voltammetric measurements and impedimetric measurements, respectively. The decision fusion based on DS evidence theory improves the total recognition accuracy to 91.60%, thus realizing significantly high accuracy in comparison to the state-of-the-art. In comparison, the feature fusion for both voltammetric and impedimetric features in one step reaches an accuracy of only 89.13%. The proposed hierarchical framework considers for the first time the fusion of impedimetric and voltammetric data and features from multiple electrochemical sensor arrays. The developed approach can be implemented for several further applications of pattern fusion, e.g., for electronic noses, measurement of environmental contaminants such as heavy metal ions, pesticides, explosives, and measurement of biomarkers, such as for the detection of cancers and diabetes. Full article
(This article belongs to the Special Issue Chemometrics for Analytical Chemistry)
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16 pages, 2120 KiB  
Article
A Novel Synthesis of a Magnetic Porous Imprinted Polymer by Polyol Method Coupled with Electrochemical Biomimetic Sensor for the Detection of Folate in Food Samples
by Sabir Khan, Ademar Wong, Michael Rychlik and María del Pilar Taboada Sotomayor
Chemosensors 2022, 10(11), 473; https://doi.org/10.3390/chemosensors10110473 - 11 Nov 2022
Cited by 12 | Viewed by 1661
Abstract
The present study reports the development and application of a novel, sensitive, and selective voltammetric sensor for the quantitation of folate or vitamin B9 in foodstuffs. The sensor was made from magnetic molecularly imprinted polymers (MMIPs), which were synthesized by the core–shell [...] Read more.
The present study reports the development and application of a novel, sensitive, and selective voltammetric sensor for the quantitation of folate or vitamin B9 in foodstuffs. The sensor was made from magnetic molecularly imprinted polymers (MMIPs), which were synthesized by the core–shell method using magnetite nanoparticles obtained by the polyol method. The MMIP-based sensor was used for the selective and specific detection of folate in different food samples. The MMIP material was constructed using magnetic water-dispersible nanomaterial, which was prepared by immersing iron (III) acetylacetonate in tri-ethylene-glycol (TEG) solvent. The magnetic water-dispersible nanomaterial was then subjected to polymerization using allyl alcohol as a functional monomer, ethylene-glycol-dimethacrylate (EGDMA) as a cross-linking agent, and 2,2-Azobisisobutyronitrile (AIBN) as a radical initiator. The proposed magnetic materials were characterized by Brunauer–Emmett–Teller (BET), field emission gun scanning electron microscopy (FEG-SEM), thermogravimetric analysis (TGA), and vibrating sample magnetometer (VSM) analysis. The quantification of folate was performed by square wave voltammetry under optimized conditions using 15 mg of MMIPs and 85 mg of carbon paste. The modified electrode presented a linear dynamic range (LDR) of 2.0–12 µmol L−1 and a limit of detection (LOD) of 1.0 × 10−7 mol L−1 in 0.1 mol L−1 acetate buffer solution (pH 4.0). The proposed sensor was successfully applied for folate detection in different food samples, where recovery percentages ranging from 93 to 103% were obtained. Finally, the results obtained from the analysis of selectivity showed that the modified biomimetic sensor is highly efficient for folate determination in real food samples. Adsorption tests were used to evaluate and compare the efficiency of the MMIPs and magnetic non-molecularly imprinted polymer (MNIPs)—used as control material, through the application of HPLC as a standard method. Full article
(This article belongs to the Special Issue Molecularly Imprinted Plasmonic Sensor)
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13 pages, 3098 KiB  
Article
Elemental Determination in Stainless Steel via Laser-Induced Breakdown Spectroscopy and Back-Propagation Artificial Intelligence Network with Spectral Pre-Processing
by Yang Ni, Bowen Fan, Bin Fang, Jiuling Meng, Yubo Zhang and Tao Lü
Chemosensors 2022, 10(11), 472; https://doi.org/10.3390/chemosensors10110472 - 11 Nov 2022
Cited by 1 | Viewed by 1488
Abstract
Minor elements significantly influence the properties of stainless steel. In this study, a laser-induced breakdown spectroscopy (LIBS) technique combined with a back-propagation artificial intelligence network (BP-ANN) was used to detect nickel (Ni), chromium (Cr), and titanium (Ti) in stainless steel. For data pre-processing, [...] Read more.
Minor elements significantly influence the properties of stainless steel. In this study, a laser-induced breakdown spectroscopy (LIBS) technique combined with a back-propagation artificial intelligence network (BP-ANN) was used to detect nickel (Ni), chromium (Cr), and titanium (Ti) in stainless steel. For data pre-processing, cubic spline interpolation and wavelet threshold transform algorithms were used to perform baseline removal and denoising. The results show that this set of pre-processing methods can effectively improve the signal-to-noise ratio, remove the baseline of spectral baseline, reduce the average relative error, and reduce relative standard deviation of BP-ANN predictions. It indicates that BP-ANN combined with pre-processing methods has promising applications for the determination of Ni, Cr, and Ti in stainless steel with LIBS and improves prediction accuracy and stability. Full article
(This article belongs to the Special Issue Application of Laser-Induced Breakdown Spectroscopy)
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22 pages, 1969 KiB  
Review
Progress of Near-Infrared-Based Medical Imaging and Cancer Cell Suppressors
by Vicky Mudeng, Gelan Ayana, Sung-Uk Zhang and Se-woon Choe
Chemosensors 2022, 10(11), 471; https://doi.org/10.3390/chemosensors10110471 - 11 Nov 2022
Cited by 3 | Viewed by 1824
Abstract
Diffuse optical tomography, an imaging modality that utilizes near-infrared light, is a new way to assess soft tissue. It provides a non-invasive screening of soft tissue, such as the breast in females and prostate in males, to inspect the existence of cancer. This [...] Read more.
Diffuse optical tomography, an imaging modality that utilizes near-infrared light, is a new way to assess soft tissue. It provides a non-invasive screening of soft tissue, such as the breast in females and prostate in males, to inspect the existence of cancer. This new imaging method is considered cost-effective and preferred because the implementation is simply through the application of a laser or light-emitting diode as a light source. Near-infrared technology does not only offer cancer screening modality, but also acts as a cancer treatment method, called near-infrared photoimmunotherapy. Despite plentiful studies in the area of near-infrared technology for cancer imaging and cancer cell suppression, there is no consolidated review that provides an overview of near-infrared application in cancer cell imaging and therapy. The objective of this study is to review near-infrared-based medical imaging and novel approaches to eradicate cancer cells. Additionally, we have discussed prospective instrumentation to establish cancer therapeutics apparatuses based on near-infrared technology. This review is expected to guide researchers implementing near-infrared for a medical imaging modality and cancer suppression in vitro, in vivo, and in clinical settings. Full article
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13 pages, 7323 KiB  
Article
Gas Sensors Based on Exfoliated g-C3N4 for CO2 Detection
by Ahmed Kotbi, Manal Benyoussef, El Mostafa Ressami, Michael Lejeune, Brahim Lakssir and Mustapha Jouiad
Chemosensors 2022, 10(11), 470; https://doi.org/10.3390/chemosensors10110470 - 10 Nov 2022
Cited by 7 | Viewed by 2079
Abstract
We report on the investigation of graphitic carbon nitride (g-C3N4) for carbon dioxide (CO2) sensor applications. g-C3N4 is prepared by the thermal polycondensation of thiourea and sprayed onto a substrate with interdigitated electrodes. The [...] Read more.
We report on the investigation of graphitic carbon nitride (g-C3N4) for carbon dioxide (CO2) sensor applications. g-C3N4 is prepared by the thermal polycondensation of thiourea and sprayed onto a substrate with interdigitated electrodes. The resulting sensor device exhibited a high sensitivity to CO2 molecules of ~200 ppm, a high responsivity of ~730 ms at 40 °C and a full recovery time of 36 s. Furthermore, a set of various characterization measurements demonstrated the excellent stability of both the g-C3N4 nanosheets and the fabricated gas sensor device. Meanwhile, density functional theory (DFT) calculations for the bulk and monolayer models, based on tri-s-triazine, revealed the optoelectronic properties of g-C3N4 and the interaction energy with CO2, which is evaluated at −0.59 eV. This value indicates the very good affinity of g-C3N4 nanosheets to CO2 molecules. Our findings shed light on the potential for g-C3N4 to be used for the development of high-performing gas sensor devices. Full article
(This article belongs to the Special Issue Gas Sensors for Monitoring Environmental Changes)
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13 pages, 4774 KiB  
Article
Organic-Inorganic Semiconductor Heterojunction P3HT@Ag2NCN Composite Film as a Recyclable SERS Substrate for Molecule Detection Application
by Lin Xu, Tao Wang, Xuan Li and Zhengjian Chen
Chemosensors 2022, 10(11), 469; https://doi.org/10.3390/chemosensors10110469 - 10 Nov 2022
Cited by 2 | Viewed by 1718
Abstract
Semiconductor composite materials have attracted interest from surface-enhanced Raman scattering (SERS) substrate research. Here, we investigate an organic-inorganic semiconductor heterojunction P3HT@Ag2NCN composite film as a recyclable SERS substrate for molecule detection application. Our study shows that the SERS substrate of the [...] Read more.
Semiconductor composite materials have attracted interest from surface-enhanced Raman scattering (SERS) substrate research. Here, we investigate an organic-inorganic semiconductor heterojunction P3HT@Ag2NCN composite film as a recyclable SERS substrate for molecule detection application. Our study shows that the SERS substrate of the composite P3HT@Ag2NCN composite film has high sensitivity, excellent signal reproducibility, and is reusable. Significant π-stacking of the probe molecules with the thiophene π-cores molecules from P3HT plays an important role in the large SERS enhancement by the charge transfer mechanism. Due to physical interaction between P3HT and Ag2NCN, the organic-inorganic semiconductor heterojunction structure further improves charge transfer efficiency and the SERS property. Our results show that the enhancement factor (EF) of P3HT@Ag2NCN composite films (EF = 6147 ± 300) for the probe molecule methylene blue is more than 7 times that of P3HT substrate (EF = 848 ± 85) and is about 75 times that of Ag2NCN nanorods (EF = 82 ± 8). In addition, the SERS substrates of the P3HT@Ag2NCN composite film also display excellent reusability and signal reproducibility (RSD < 4.8%). Our study opens up a new opportunity for designing an ideal SERS substrate with high sensitivity, selectivity, long-term stability, low cost, and reusability. Full article
(This article belongs to the Special Issue Nanocomposites for SERS Sensing)
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19 pages, 4174 KiB  
Review
Deferoxamine-Based Materials and Sensors for Fe(III) Detection
by Giancarla Alberti, Camilla Zanoni, Lisa Rita Magnaghi and Raffaela Biesuz
Chemosensors 2022, 10(11), 468; https://doi.org/10.3390/chemosensors10110468 - 9 Nov 2022
Cited by 10 | Viewed by 2909
Abstract
Deferoxamine (DFO) is a siderophore widely studied for its ability to bind iron(III) strongly. Thanks to its versatility, it is suitable for several clinical and analytical applications, from the recognized iron(III) chelation therapy to the most recent applications in sensing. The presence of [...] Read more.
Deferoxamine (DFO) is a siderophore widely studied for its ability to bind iron(III) strongly. Thanks to its versatility, it is suitable for several clinical and analytical applications, from the recognized iron(III) chelation therapy to the most recent applications in sensing. The presence of three hydroxamic functional groups enables Deferoxamine to form stable complexes with iron(III) and other divalent and trivalent metal ions. Moreover, the terminal amino group in the DFO molecule, not involved in metal ion complexation, allows modification or functionalization of solid phases, nanoobjects, biopolymers, electrodes and optical devices. This review summarizes and discusses deferoxamine-based applications for the chelation and recognition of Fe(III). Full article
(This article belongs to the Special Issue Chemosensors for Ion Detection)
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13 pages, 2543 KiB  
Article
Enhanced Gas Detection by Altering Gate Voltage Polarity of Polypyrrole/Graphene Field-Effect Transistor Sensor
by Xiaohui Tang, Jean-Pierre Raskin, Nicolas Reckinger, Yiyi Yan, Nicolas André, Driss Lahem and Marc Debliquy
Chemosensors 2022, 10(11), 467; https://doi.org/10.3390/chemosensors10110467 - 9 Nov 2022
Cited by 6 | Viewed by 1783
Abstract
This work introduces a new measurement methodology for enhancing gas detection by tuning the magnitude and polarity of back-gate voltage of a field-effect transistor (FET)-based sensor. The aim is to simultaneously strengthen the sensor response and accelerate the sensor recovery. In addition, this [...] Read more.
This work introduces a new measurement methodology for enhancing gas detection by tuning the magnitude and polarity of back-gate voltage of a field-effect transistor (FET)-based sensor. The aim is to simultaneously strengthen the sensor response and accelerate the sensor recovery. In addition, this methodology can consume less energy compared with conventional measurements by direct current bias. To illustrate the benefits of the proposed methodology, we fabricated and characterized a polypyrrole/graphene (PPy/G) FET sensor for ammonia (NH3) detection. Our experiment, simulation and calculation results demonstrated that the redox reaction between the NH3 molecules and the PPy/G sensitive layer could be controlled by altering the polarity and the magnitude of the back-gate voltage. This proof-of-principle measurement methodology, which solves the inherent contradiction between high response and slow recovery of the chemiresistive sensor, could be extended to detect other gases, so as to improve global gas measurement systems. It opens up a new route for FET-based gas sensors in practical applications. Full article
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12 pages, 2857 KiB  
Article
The Role of the Synthesis Routes on the CO-Sensing Mechanism of NiO-Based Gas Sensors
by Adelina Stanoiu, Corneliu Ghica, Catalina Gabriela Mihalcea, Daniela Ghica and Cristian Eugen Simion
Chemosensors 2022, 10(11), 466; https://doi.org/10.3390/chemosensors10110466 - 9 Nov 2022
Cited by 2 | Viewed by 1440
Abstract
In this study, two alternative synthesis routes have been used in obtaining gas-sensitive NiO materials. The structural and morphological aspects were systematically investigated by X-ray diffraction (XRD) and transmission electron microscopy (TEM), revealing significant differences further mirrored in their sensing performances. Simultaneous electrical [...] Read more.
In this study, two alternative synthesis routes have been used in obtaining gas-sensitive NiO materials. The structural and morphological aspects were systematically investigated by X-ray diffraction (XRD) and transmission electron microscopy (TEM), revealing significant differences further mirrored in their sensing performances. Simultaneous electrical resistance and contact potential differences have been involved aiming to decouple the energetic contributions: work function (ΔΦ), surface band bending (qΔVs) and electron affinity (Δχ). Two sensing mechanism scenarios explained the enhancement and downgrading in the sensor response to carbon monoxide (CO) concerning the synthesis strategies. The role of relative humidity (RH) was considered throughout the electrical operando (in-field) investigations. Full article
(This article belongs to the Special Issue Application and Advance of Gas Sensors)
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18 pages, 1263 KiB  
Review
Total Ion Chromatogram and Total Ion Mass Spectrum as Alternative Tools for Detection and Discrimination (A Review)
by Marta Barea-Sepúlveda, Hugo Duarte, María José Aliaño-González, Anabela Romano and Bruno Medronho
Chemosensors 2022, 10(11), 465; https://doi.org/10.3390/chemosensors10110465 - 8 Nov 2022
Cited by 7 | Viewed by 3853
Abstract
Gas chromatography (GC) and mass spectrometry (MS) are widely used techniques in the analysis of complex mixtures due to their various advantages, such as high selectivity, reproducibility, precision, and sensitivity. However, the data processing is often complex and time-consuming and requires a great [...] Read more.
Gas chromatography (GC) and mass spectrometry (MS) are widely used techniques in the analysis of complex mixtures due to their various advantages, such as high selectivity, reproducibility, precision, and sensitivity. However, the data processing is often complex and time-consuming and requires a great deal of experience, which might be a serious drawback in certain areas, such as quality control, or regarding research in the field of medicine or forensic sciences, where time plays a crucial role. For these reasons, some authors have proposed the use of alternative data processing approaches, such as the total ion chromatogram or total mass spectrum, allowing these techniques to be treated as sensors where each retention time or ratio m/z acts as a sensor collecting total intensities. In this way, the main advantages associated with both techniques are maintained, but the outcomes from the analysis can be reached in a faster, simpler, and an almost automated way. In this review, the main features of the GC- and MS-based analysis methodologies and the ways in which to apply them are highlighted. Moreover, their implementation in different fields, such as agri-food, forensics, environmental sciences, or medicine is discussed, highlighting important advantages as well as limitations. Full article
(This article belongs to the Special Issue GC, MS and GC-MS Analytical Methods: Opportunities and Challenges)
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