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Chemosensors
Volume 9
Issue 10
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Chemosensors, Volume 9, Issue 10 (October 2021) – 22 articles

Cover Story (view full-size image): A microdevice requiring low power consumption to perform essential tests can be vital for scientific discovery or can significantly improve tests when conducting research in an isolated area or on field where access to electricity is extremely limited. Utilizing the wasted heat from daily activities, temperature difference in the environment, or simply from body heat to generate power using a thermoelectric generator, can be sufficient for operating the microdevices. Although the thermoelectric generator is robust and easy to operate, searching for a heat source and heat sink is a problem for this approach. Fortunately, the atmospheric infrared window allows for the utilization of outer space as a heat sink, and therefore, thermoelectric generator can be readily operated. View this paper.
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16 pages, 4783 KiB  
Article
Rapid Algae Identification and Concentration Prediction Based on Discrete Excitation Fluorescence Spectra
by Shihan Shan, Xiaoping Wang, Zhuoyun Xu and Mengmeng Tong
Chemosensors 2021, 9(10), 293; https://doi.org/10.3390/chemosensors9100293 - 18 Oct 2021
Cited by 2 | Viewed by 2574
Abstract
In this paper, an algal identification and concentration determination method based on discrete excitation fluorescence spectra is proposed for online algae identification and concentration prediction. The discrete excitation fluorescence spectra of eight species of harmful algae from four algal categories were assessed. After [...] Read more.
In this paper, an algal identification and concentration determination method based on discrete excitation fluorescence spectra is proposed for online algae identification and concentration prediction. The discrete excitation fluorescence spectra of eight species of harmful algae from four algal categories were assessed. After determining typical excitation wavelengths according to the distribution of photosynthetic pigments and eliminating strongly correlated wavelengths by applying the hierarchical clustering, seven characteristic excitation wavelengths (405, 435, 470, 490, 535, 555, and 590 nm) were selected. By adding the ratios between feature points (435 and 470 nm, 470 and 490 nm, as well as 535 and 555 nm), standard feature spectra were established for classification. The classification accuracy in pure samples exceeded 95%, and that of dominant algae species in a mixed sample was 77.4%. Prediction of algae concentration was achieved by establishing linear regression models between fluorescence intensity at seven characteristic excitation wavelengths and concentrations. All models performed better at low concentrations, not exceeding the threshold concentration of red tide algae outbreak, which provides a proximate cell density of dominant algal species. Full article
(This article belongs to the Section Optical Chemical Sensors)
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12 pages, 4054 KiB  
Article
Off-Grid Electrical Cell Lysis Microfluidic Device Utilizing Thermoelectricity and Thermal Radiation
by Duong-Duy Duong and Nae-Yoon Lee
Chemosensors 2021, 9(10), 292; https://doi.org/10.3390/chemosensors9100292 - 14 Oct 2021
Cited by 1 | Viewed by 2224
Abstract
Microfluidic devices have enormous potential and a wide range of applications. However, most applications end up as chip-in-a-lab systems because of power source constraints. This work focuses on reducing the reliance on the power network and expanding on the concept of a lab-on-a-chip [...] Read more.
Microfluidic devices have enormous potential and a wide range of applications. However, most applications end up as chip-in-a-lab systems because of power source constraints. This work focuses on reducing the reliance on the power network and expanding on the concept of a lab-on-a-chip for microfluidic devices. A cellulose-based radiator to reflect infrared (IR) radiation with wavelengths within the atmospheric window (8–13 µm) into outer space was fabricated. This process lowered the temperature inside the insulated environment. The difference in temperature was used to power a thermoelectric generator (TEG) and generate an electric current. This electric current was run through a DC-DC transformer to increase the voltage before being used to perform electrical cell lysis with a microfluidic device. This experimental setup successfully achieved 90% and 50% cell lysis efficiencies in ideal conditions and in field tests, respectively. This work demonstrated the possibility of utilizing the unique characteristics of a microfluidic device to perform an energy-intensive assay with minimal energy generated from a TEG and no initial power input for the system. The TEG system also required less maintenance than solar, wind, or hydroelectricity. The IR radiation process naturally allows for more dynamic working conditions for the entire system. Full article
(This article belongs to the Special Issue Microfluidic Biosensing Platform)
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40 pages, 2198 KiB  
Review
Sensing Methods for Hazardous Phenolic Compounds Based on Graphene and Conducting Polymers-Based Materials
by Hazwani Suhaila Hashim, Yap Wing Fen, Nur Alia Sheh Omar and Nurul Illya Muhamad Fauzi
Chemosensors 2021, 9(10), 291; https://doi.org/10.3390/chemosensors9100291 - 14 Oct 2021
Cited by 16 | Viewed by 3318
Abstract
It has been known for years that the phenolic compounds are able to exert harmful effects toward living organisms including humans due to their high toxicity. Living organisms were exposed to these phenolic compounds as they were released into the environment as waste [...] Read more.
It has been known for years that the phenolic compounds are able to exert harmful effects toward living organisms including humans due to their high toxicity. Living organisms were exposed to these phenolic compounds as they were released into the environment as waste products from several fast-growing industries. In this regard, tremendous efforts have been made by researchers to develop sensing methods for the detection of these phenolic compounds. Graphene and conducting polymers-based materials have arisen as a high potential sensing layer to improve the performance of the developed sensors. Henceforth, this paper reviews the existing investigations on graphene and conducting polymer-based materials incorporated with various sensors that aimed to detect hazardous phenolic compounds, i.e., phenol, 2-chlorophenol, 2,4-dichlorophenol, 2,4,6-trichlorophenol, pentachlorophenol, 2-nitrophenol, 4-nitrophenol, 2,4-dinitrophenol, and 2,4-dimethylphenol. The whole picture and up-to-date information on the graphene and conducting polymers-based sensors are arranged in systematic chronological order to provide a clearer insight in this research area. The future perspectives of this study are also included, and the development of sensing methods for hazardous phenolic compounds using graphene and conducting polymers-based materials is expected to grow more in the future. Full article
(This article belongs to the Collection Sensing Materials: Advances in Synthesis, Functionalities, and Applications)
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13 pages, 1631 KiB  
Communication
Mercaptosuccinic-Acid-Functionalized Gold Nanoparticles for Highly Sensitive Colorimetric Sensing of Fe(III) Ions
by Nadezhda S. Komova, Kseniya V. Serebrennikova, Anna N. Berlina, Svetlana M. Pridvorova, Anatoly V. Zherdev and Boris B. Dzantiev
Chemosensors 2021, 9(10), 290; https://doi.org/10.3390/chemosensors9100290 - 14 Oct 2021
Cited by 8 | Viewed by 2869
Abstract
The development of reliable and highly sensitive methods for heavy metal detection is a critical task for protecting the environment and human health. In this study, a qualitative colorimetric sensor that used mercaptosuccinic-acid-functionalized gold nanoparticles (MSA-AuNPs) to detect trace amounts of Fe(III) ions [...] Read more.
The development of reliable and highly sensitive methods for heavy metal detection is a critical task for protecting the environment and human health. In this study, a qualitative colorimetric sensor that used mercaptosuccinic-acid-functionalized gold nanoparticles (MSA-AuNPs) to detect trace amounts of Fe(III) ions was developed. MSA-AuNPs were prepared using a one-step reaction, where mercaptosuccinic acid (MSA) was used for both stabilization, which was provided by the presence of two carboxyl groups, and functionalization of the gold nanoparticle (AuNP) surface. The chelating properties of MSA in the presence of Fe(III) ions and the concentration-dependent aggregation of AuNPs showed the effectiveness of MSA-AuNPs as a sensing probe with the use of an absorbance ratio of A530/A650 as an analytical signal in the developed qualitative assay. Furthermore, the obvious Fe(III)-dependent change in the color of the MSA-AuNP solution from red to gray-blue made it possible to visually assess the metal content in a concentration above the detection limit with an assay time of less than 1 min. The detection limit that was achieved (23 ng/mL) using the proposed colorimetric sensor is more than 10 times lower than the maximum allowable concentration for drinking water defined by the World Health Organization (WHO). The MSA-AuNPs were successfully applied for Fe(III) determination in tap, spring, and drinking water, with a recovery range from 89.6 to 126%. Thus, the practicality of the MSA-AuNP-based sensor and its potential for detecting Fe(III) in real water samples were confirmed by the rapidity of testing and its high sensitivity and selectivity in the presence of competing metal ions. Full article
(This article belongs to the Special Issue Selected Papers from 1st International Electronic Conference on Chemical Sensors and Analytical Chemistry (CSAC2021))
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19 pages, 2864 KiB  
Review
Sensitive Electrochemical Detection of Bioactive Molecules (Hydrogen Peroxide, Glucose, Dopamine) with Perovskites-Based Sensors
by Imane Boubezari, Ali Zazoua, Abdelhamid Errachid and Nicole Jaffrezic-Renault
Chemosensors 2021, 9(10), 289; https://doi.org/10.3390/chemosensors9100289 - 12 Oct 2021
Cited by 10 | Viewed by 3475
Abstract
Perovskite-modified electrodes have received increasing attention in the last decade, due to their electrocatalytic properties to undergo the sensitive and selective detection of bioactive molecules, such as hydrogen peroxide, glucose, and dopamine. In this review paper, different types of perovskites involved for their [...] Read more.
Perovskite-modified electrodes have received increasing attention in the last decade, due to their electrocatalytic properties to undergo the sensitive and selective detection of bioactive molecules, such as hydrogen peroxide, glucose, and dopamine. In this review paper, different types of perovskites involved for their electrocatalytic properties are described, and the proposed mechanism of detection is presented. The analytical performances obtained for different electroactive molecules are listed and compared with those in terms of the type of perovskite used, its nanostructuration, and its association with other conductive nanomaterials. The analytical performance obtained with perovskites is shown to be better than those of Ni and Co oxide-based electrochemical sensors. Main trends and future challenges for enlarging and improving the use of perovskite-based electrochemical sensors are then discussed. Full article
(This article belongs to the Section Electrochemical Devices and Sensors)
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10 pages, 16199 KiB  
Communication
Electrical and Humidity-Sensing Properties of EuCl2, Eu2O3 and EuCl2/Eu2O3 Blend Films
by Pi-Guey Su and Nok-Him Choy
Chemosensors 2021, 9(10), 288; https://doi.org/10.3390/chemosensors9100288 - 11 Oct 2021
Cited by 1 | Viewed by 1897
Abstract
Impedance-type humidity sensors based on EuCl2, Eu2O3 and EuCl2/Eu2O3 blend films were fabricated. The electrical properties of the pure EuCl2 and Eu2O3 films and EuCl2/Eu2O [...] Read more.
Impedance-type humidity sensors based on EuCl2, Eu2O3 and EuCl2/Eu2O3 blend films were fabricated. The electrical properties of the pure EuCl2 and Eu2O3 films and EuCl2/Eu2O3 blend film that was blended with different amounts of EuCl2 were investigated as functions of relative humidity. The influences of the EuCl2 to the humidity-sensing properties (sensitivity and linearity) of the EuCl2/Eu2O3 blend film were thus elucidated. The impedance-type humidity sensor that was made of a 7 wt% EuCl2/Eu2O3 blend film exhibited the highest sensitivity, best linearity, a small hysteresis, a fast response time, a small temperature coefficient and long-term stability. The complex impedance plots were used to elucidate the role of ions in the humidity-sensing behavior of the EuCl2/Eu2O3 blend film. Full article
(This article belongs to the Section Electrochemical Devices and Sensors)
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12 pages, 4514 KiB  
Article
Spectroscopic and Colorimetric Studies for Anions with a New Urea-Based Molecular Cleft
by Sanchita Kundu, Tochukwu Kevin Egboluche, Zehra Yousuf and Md. Alamgir Hossain
Chemosensors 2021, 9(10), 287; https://doi.org/10.3390/chemosensors9100287 - 11 Oct 2021
Cited by 6 | Viewed by 1966
Abstract
A new simple urea-based dipodal molecular cleft (L) has been synthesized and studied for its binding affinity for a variety of anions by 1H-NMR, UV-Vis and colorimetric techniques in DMSO-d6 and DMSO, respectively. The results from titration studies [...] Read more.
A new simple urea-based dipodal molecular cleft (L) has been synthesized and studied for its binding affinity for a variety of anions by 1H-NMR, UV-Vis and colorimetric techniques in DMSO-d6 and DMSO, respectively. The results from titration studies suggest that the receptor forms a 1:2 complex with each of the anions used via hydrogen bonding interactions and exhibits strong selectivity for fluoride among halides, showing the binding affinity in the order of fluoride > chloride > bromide > iodide; meanwhile, it displays moderate selectivity for acetate among oxoanions, showing the binding affinity in the order of acetate > dihydrogen phosphate > bicarbonate > hydrogen sulfate > nitrate. Colorimetric studies of L for anions in DMSO reveal that the receptor is capable of detecting fluoride, acetate, bicarbonate and dihydrogen phosphate, displaying a visible color change in the presence of the respective anions. Full article
(This article belongs to the Special Issue Progress of Nanomaterials for Colorimetric Sensing)
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12 pages, 2374 KiB  
Article
Paper-Based Device for Sweat Chloride Testing Based on the Photochemical Response of Silver Halide Nanocrystals
by Tatiana G. Choleva, Christina Matiaki, Afroditi Sfakianaki, Athanasios G. Vlessidis and Dimosthenis L. Giokas
Chemosensors 2021, 9(10), 286; https://doi.org/10.3390/chemosensors9100286 - 8 Oct 2021
Cited by 4 | Viewed by 2603
Abstract
A new method for the determination of chloride anions in sweat is described. The novelty of the method relies on the different photochemical response of silver ions and silver chloride crystals when exposed to UV light. Silver ions undergo an intense colorimetric transition [...] Read more.
A new method for the determination of chloride anions in sweat is described. The novelty of the method relies on the different photochemical response of silver ions and silver chloride crystals when exposed to UV light. Silver ions undergo an intense colorimetric transition from colorless to dark grey-brown due to the formation of nanosized Ag while AgCl exhibits a less intense color change from white to slightly grey. The analytical signal is obtained as mean grey value of color intensity on the paper surface and is expressed as the absolute difference between the signal of the blank (i.e., in absence of chloride) and the sample (i.e., in the presence of chloride). The method is simple to perform (addition of sample, incubation in the absence of light, irradiation, and offline measurement in a flatbed scanner), does not require any special signal processing steps (the color intensity is directly measured from a constant window on the paper surface without any imager processing) and is performed with minimum sample volume (2 μL). The method operates within a large chloride concentration range (10–140 mM) with good detection limits (2.7 mM chloride), satisfactory recoveries (95.2–108.7%), and reproducibility (<9%). Based on these data the method could serve as a potential tool for the diagnosis of cystic fibrosis through the determination of chloride in human sweat. Full article
(This article belongs to the Special Issue Paper-Based Sensors and Microfluidic Devices)
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14 pages, 3963 KiB  
Article
Tetraphenylethylene-Substituted Bis(thienyl)imidazole (DTITPE), An Efficient Molecular Sensor for the Detection and Quantification of Fluoride Ions
by Ranjith Kumar Jakku, Nedaossadat Mirzadeh, Steven H. Privér, Govind Reddy, Anil Kumar Vardhaman, Giribabu Lingamallu, Rajiv Trivedi and Suresh Kumar Bhargava
Chemosensors 2021, 9(10), 285; https://doi.org/10.3390/chemosensors9100285 - 6 Oct 2021
Cited by 7 | Viewed by 3211
Abstract
Fluoride ion plays a pivotal role in a range of biological and chemical applications however excessive exposure can cause severe kidney and gastric problems. A simple and selective molecular sensor, 4,5-di(thien-2-yl)-2-(4-(1,2,2-triphenylvinyl)-phenyl)-1H-imidazole, DTITPE, has been synthesized for the detection of fluoride ions, with detection [...] Read more.
Fluoride ion plays a pivotal role in a range of biological and chemical applications however excessive exposure can cause severe kidney and gastric problems. A simple and selective molecular sensor, 4,5-di(thien-2-yl)-2-(4-(1,2,2-triphenylvinyl)-phenyl)-1H-imidazole, DTITPE, has been synthesized for the detection of fluoride ions, with detection limits of 1.37 × 10−7 M and 2.67 × 10−13 M, determined by UV-vis. and fluorescence spectroscopy, respectively. The variation in the optical properties of the molecular sensor in the presence of fluoride ions was explained by an intermolecular charge transfer (ICT) process between the bis(thienyl) and tetraphenylethylene (TPE) moieties upon the formation of a N-H---F− hydrogen bond of the imidazole proton. The sensing mechanism exhibited by DTITPE for fluoride ions was confirmed by 1H NMR spectroscopic studies and density functional theory (DFT) calculations. Test strips coated with the molecular sensor can detect fluoride ions in THF, undergoing a color change from white to yellow, which can be observed with the naked eye, showcasing their potential real-world application. Full article
(This article belongs to the Special Issue Gas Sensors: Simulation, Modeling, and Characterization)
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12 pages, 6154 KiB  
Article
Ppb-Level Butanone Sensor Based on ZnO-TiO2-rGO Nanocomposites
by Zhijia Liao, Yao Yu, Zhenyu Yuan and Fanli Meng
Chemosensors 2021, 9(10), 284; https://doi.org/10.3390/chemosensors9100284 - 6 Oct 2021
Cited by 7 | Viewed by 2462
Abstract
In this paper, ZnO-TiO2-rGO nanocomposites were successfully synthesized by the hydrothermal method. The morphology and structure of the synthesized nanomaterials were characterized by SEM, XRD, HRTEM, and XPS. Butanone is a typical ketone product. The vapors are extremely harmful once exposed, [...] Read more.
In this paper, ZnO-TiO2-rGO nanocomposites were successfully synthesized by the hydrothermal method. The morphology and structure of the synthesized nanomaterials were characterized by SEM, XRD, HRTEM, and XPS. Butanone is a typical ketone product. The vapors are extremely harmful once exposed, triggering skin irritation in mild cases and affecting our breathing in severe cases. In this paper, the gas-sensing properties of TiO2, ZnO, ZnO-TiO2, and ZnO-TiO2-rGO nanomaterials to butanone vapor were studied. The optimum operating temperature of the ZnO-TiO2-rGO sensor is 145 °C, which is substantially lower than the other three sensors. The selectivity for butanone vapor is greatly improved, and the response is 5.6 times higher than that of other organic gases. The lower detection limit to butanone can reach 63 ppb. Therefore, the ZnO-TiO2-rGO sensor demonstrates excellent gas-sensing performance to butanone. Meanwhile, the gas-sensing mechanism of the ZnO-TiO2-rGO sensor to butanone vapor was also analyzed. Full article
(This article belongs to the Special Issue 2D Materials for Gas Sensing)
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14 pages, 3598 KiB  
Article
pH-Induced Modulation of Vibrio fischeri Population Life Cycle
by Ana Rita Silva, Cláudia Sousa, Daniela Exner, Ruth Schwaiger, Maria Madalena Alves, Dmitri Y. Petrovykh and Luciana Pereira
Chemosensors 2021, 9(10), 283; https://doi.org/10.3390/chemosensors9100283 - 5 Oct 2021
Cited by 4 | Viewed by 3691
Abstract
Commonly used as biological chemosensors in toxicity assays, Vibrio fischeri bacteria were systematically characterized using complementary physicochemical and biological techniques to elucidate the evolution of their properties under varying environmental conditions. Changing the pH above or below the optimal pH 7 was used [...] Read more.
Commonly used as biological chemosensors in toxicity assays, Vibrio fischeri bacteria were systematically characterized using complementary physicochemical and biological techniques to elucidate the evolution of their properties under varying environmental conditions. Changing the pH above or below the optimal pH 7 was used to model the long-term stress that would be experienced by V. fischeri in environmental toxicology assays. The spectral shape of bioluminescence and cell-surface charge during the exponential growth phase were largely unaffected by pH changes. The pH-induced modulation of V. fischeri growth, monitored via the optical density (OD), was moderate. In contrast, the concomitant changes in the time-profiles of their bioluminescence, which is used as the readout in assays, were more significant. Imaging at discrete timepoints by scanning electron microscopy (SEM) and helium-ion microscopy (HIM) revealed that mature V. fischeri cells maintained a rod-shaped morphology with the average length of 2.2 ± 1 µm and diameter of 0.6 ± 0.1 µm. Detailed morphological analysis revealed subpopulations of rods having aspect ratios significantly larger than those of average individuals, suggesting the use of such elongated rods as an indicator of the multigenerational environmental stress. The observed modulation of bioluminescence and morphology supports the suitability of V. fischeri as biological chemosensors for both rapid and long-term assays, including under environmental conditions that can modify the physicochemical properties of novel anthropogenic pollutants, such as nanomaterials and especially stimulus-responsive nanomaterials. Full article
(This article belongs to the Special Issue Nanotechnology for Sensing, Medical and Environmental Application)
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18 pages, 2423 KiB  
Review
Conductive Hydrogel-Based Electrochemical Sensor: A Soft Platform for Capturing Analyte
by Li Fu, Aimin Yu and Guosong Lai
Chemosensors 2021, 9(10), 282; https://doi.org/10.3390/chemosensors9100282 - 4 Oct 2021
Cited by 45 | Viewed by 6623
Abstract
Electrode modifications for electrochemical sensors attract a lot of attention every year. Among them, hydrogels are a relatively special class of electrode modifier. Since hydrogels often contain polymers, even though they are conductive polymers, they are not ideal electrode modifiers because of their [...] Read more.
Electrode modifications for electrochemical sensors attract a lot of attention every year. Among them, hydrogels are a relatively special class of electrode modifier. Since hydrogels often contain polymers, even though they are conductive polymers, they are not ideal electrode modifiers because of their poor conductivity. However, the micro-aqueous environment and the three-dimensional structure of hydrogels are an excellent platform for immobilizing bioactive molecules and maintaining their activity. This gives the hydrogel-modified electrochemical sensor the potential to perform specific recognition. At the same time, the rapid development of nanomaterials also makes the composite hydrogel have good electrical conductivity. This has led many scientists to become interested in hydrogel-based electrochemical sensors. In this review, we summarize the development process of hydrogel-based electrochemical sensors, starting from 2000. Hydrogel-based electrochemical sensors were initially used only as a carrier for biomolecules, mostly for loading enzymes and for specific recognition. With the widespread use of noble metal nanoparticles and carbon materials, hydrogels can now be used to prepare enzyme-free sensors. Although there are some sporadic studies on the use of hydrogels for practical applications, the vast majority of reports are still limited to the detection of common model molecules, such as glucose and H2O2. In the review, we classify hydrogels according to their different conducting strategies, and present the current status of the application of different hydrogels in electrochemical sensors. We also summarize the advantages and shortcomings of hydrogel-based electrochemical sensors. In addition, future prospects regarding hydrogel for electrochemical sensor use have been provided at the end. Full article
(This article belongs to the Special Issue Advanced Nanomaterials for Flexible and Wearable Chemo- and Bio- Sensors)
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29 pages, 5531 KiB  
Review
Advances in Colorimetric Assay Based on AuNPs Modified by Proteins and Nucleic Acid Aptamers
by Sopio Melikishvili, Ivan Piovarci and Tibor Hianik
Chemosensors 2021, 9(10), 281; https://doi.org/10.3390/chemosensors9100281 - 2 Oct 2021
Cited by 24 | Viewed by 4442
Abstract
This review is focused on the biosensing assay based on AuNPs (AuNPs) modified by proteins, peptides and nucleic acid aptamers. The unique physical properties of AuNPs allow their modification by proteins, peptides or nucleic acid aptamers by chemisorption as well as other methods [...] Read more.
This review is focused on the biosensing assay based on AuNPs (AuNPs) modified by proteins, peptides and nucleic acid aptamers. The unique physical properties of AuNPs allow their modification by proteins, peptides or nucleic acid aptamers by chemisorption as well as other methods including physical adsorption and covalent immobilization using carbodiimide chemistry or based on strong binding of biotinylated receptors on neutravidin, streptavidin or avidin. The methods of AuNPs preparation, their chemical modification and application in several biosensing assays are presented with focus on application of nucleic acid aptamers for colorimetry assay for determination of antibiotics and bacteria in food samples. Full article
(This article belongs to the Special Issue Smart Polymer-Based Chemical and Biological Sensors)
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18 pages, 3726 KiB  
Article
Electrosynthesized Poly(o-aminophenol) Films as Biomimetic Coatings for Dopamine Detection on Pt Substrates
by Rosanna Ciriello, Martina Graziano, Giuliana Bianco and Antonio Guerrieri
Chemosensors 2021, 9(10), 280; https://doi.org/10.3390/chemosensors9100280 - 30 Sep 2021
Cited by 7 | Viewed by 3135
Abstract
Dopamine (DA) is a neurotransmitter, and its levels in the human body are associated with serious diseases. The need for a suitable detection method in medical practice has encouraged the development of electrochemical sensors that take advantage of DA electroactivity. Molecularly imprinted polymers [...] Read more.
Dopamine (DA) is a neurotransmitter, and its levels in the human body are associated with serious diseases. The need for a suitable detection method in medical practice has encouraged the development of electrochemical sensors that take advantage of DA electroactivity. Molecularly imprinted polymers (MIPs) are biomimetic materials able to selectively recognize target analytes. A novel MIP sensor for DA is proposed here based on a thin film of poly(o-aminophenol) electrosynthesized on bare Pt. A fast and easy method for executing the procedure for MIP deposition has been developed based on mild experimental conditions that are able to prevent electrode fouling from DA oxidation products. The MIP exhibited a limit of detection of 0.65 μM, and appreciable reproducibility and stability. The high recognition capability of poly(o-aminophenol) towards DA allowed for the achievement of notable selectivity: ascorbic acid, uric acid, serotonin, and tyramine did not interfere with DA detection, even at higher concentrations. The proposed sensor was successfully applied for DA detection in urine samples, showing good recovery. Full article
(This article belongs to the Collection Electrochemical Biosensors for Medical Diagnosis)
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23 pages, 5651 KiB  
Review
Advances in Chirality Sensing with Macrocyclic Molecules
by Xiaotong Liang, Wenting Liang, Pengyue Jin, Hongtao Wang, Wanhua Wu and Cheng Yang
Chemosensors 2021, 9(10), 279; https://doi.org/10.3390/chemosensors9100279 - 29 Sep 2021
Cited by 29 | Viewed by 4375
Abstract
The construction of chemical sensors that can distinguish molecular chirality has attracted increasing attention in recent years due to the significance of chiral organic molecules and the importance of detecting their absolute configuration and chiroptical purity. The supramolecular chirality sensing strategy has shown [...] Read more.
The construction of chemical sensors that can distinguish molecular chirality has attracted increasing attention in recent years due to the significance of chiral organic molecules and the importance of detecting their absolute configuration and chiroptical purity. The supramolecular chirality sensing strategy has shown promising potential due to its advantages of high throughput, sensitivity, and fast chirality detection. This review focuses on chirality sensors based on macrocyclic compounds. Macrocyclic chirality sensors usually have inherent complexing ability towards certain chiral guests, which combined with the signal output components, could offer many unique advantages/properties compared to traditional chiral sensors. Chirality sensing based on macrocyclic sensors has shown rapid progress in recent years. This review summarizes recent advances in chirality sensing based on both achiral and chiral macrocyclic compounds, especially newly emerged macrocyclic molecules. Full article
(This article belongs to the Collection Novel Chirogenic Systems and Sensing Materials for Stereoselective Sensors Development)
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19 pages, 2860 KiB  
Article
Thiourea Organocatalysts as Emerging Chiral Pollutants: En Route to Porphyrin-Based (Chir)Optical Sensing
by Nele Konrad, Matvey Horetski, Mariliis Sihtmäe, Khai-Nghi Truong, Irina Osadchuk, Tatsiana Burankova, Marc Kielmann, Jasper Adamson, Anne Kahru, Kari Rissanen, Mathias O. Senge, Victor Borovkov, Riina Aav and Dzmitry Kananovich
Chemosensors 2021, 9(10), 278; https://doi.org/10.3390/chemosensors9100278 - 29 Sep 2021
Cited by 5 | Viewed by 4377
Abstract
Environmental pollution with chiral organic compounds is an emerging problem requiring innovative sensing methods. Amino-functionalized thioureas, such as 2-(dimethylamino)cyclohexyl-(3,5-bis(trifluoromethyl)phenyl)thiourea (Takemoto’s catalyst), are widely used organocatalysts with virtually unknown environmental safety data. Ecotoxicity studies based on the Vibrio fischeri luminescence inhibition test reveal significant [...] Read more.
Environmental pollution with chiral organic compounds is an emerging problem requiring innovative sensing methods. Amino-functionalized thioureas, such as 2-(dimethylamino)cyclohexyl-(3,5-bis(trifluoromethyl)phenyl)thiourea (Takemoto’s catalyst), are widely used organocatalysts with virtually unknown environmental safety data. Ecotoxicity studies based on the Vibrio fischeri luminescence inhibition test reveal significant toxicity of Takemoto’s catalyst (EC50 = 7.9 mg/L) and its NH2-substituted analog (EC50 = 7.2–7.4 mg/L). The observed toxic effect was pronounced by the influence of the trifluoromethyl moiety. En route to the porphyrin-based chemosensing of Takemoto-type thioureas, their supramolecular binding to a series of zinc porphyrins was studied with UV-Vis and circular dichroism (CD) spectroscopy, computational analysis and single crystal X-ray diffraction. The association constant values generally increased with the increasing electron-withdrawing properties of the porphyrins and electron-donating ability of the thioureas, a result of the predominant Zn⋯N cation–dipole (Lewis acid–base) interaction. The binding event induced a CD signal in the Soret band region of the porphyrin hosts—a crucial property for chirality sensing of Takemoto-type thioureas. Full article
(This article belongs to the Collection Novel Chirogenic Systems and Sensing Materials for Stereoselective Sensors Development)
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15 pages, 3379 KiB  
Article
Electrochemical Performance of Lithographically-Defined Micro-Electrodes for Integration and Device Applications
by Zohreh Hirbodvash, Mohamed S. E. Houache, Oleksiy Krupin, Maryam Khodami, Howard Northfield, Anthony Olivieri, Elena A. Baranova and Pierre Berini
Chemosensors 2021, 9(10), 277; https://doi.org/10.3390/chemosensors9100277 - 28 Sep 2021
Cited by 6 | Viewed by 3749
Abstract
Small; lithographically-defined and closely-spaced metallic features of dimensions and separation in the micrometer range are of strong interest as working and counter electrodes in compact electrochemical sensing devices. Such micro-electrode systems can be integrated with microfluidics and optical biosensors, such as surface plasmon [...] Read more.
Small; lithographically-defined and closely-spaced metallic features of dimensions and separation in the micrometer range are of strong interest as working and counter electrodes in compact electrochemical sensing devices. Such micro-electrode systems can be integrated with microfluidics and optical biosensors, such as surface plasmon waveguide biosensors, to enable multi-modal sensing strategies. We investigate lithographically-defined gold and platinum micro-electrodes experimentally, via cyclic voltammetry (CV) measurements obtained at various scan rates and concentrations of potassium ferricyanide as the redox species, in potassium nitrate as the supporting electrolyte. The magnitude of the double-layer capacitance is estimated using the voltammograms. Concentration curves for potassium ferricyanide are extracted from our CV measurements as a function of scan rate, and could be used as calibration curves from which an unknown concentration of potassium ferricyanide in the range of 0.5–5 mM can be determined. A blind test was done to confirm the validity of the calibration curve. The diffusion coefficient of potassium ferricyanide is also extracted from our CV measurements by fitting to the Randles–Sevcik equation (D = 4.18 × 10−10 m2/s). Our CV measurements were compared with measurements obtained using macroscopic commercial electrodes, yielding good agreement and verifying that the shape of our CV curves do not depend on micro-electrode geometry (only on area). We also compare our CV measurements with theoretical curves computed using the Butler–Volmer equation, achieving essentially perfect agreement while extracting the rate constant at zero potential for our redox species (ko = 10−6 m/s). Finally, we demonstrate the importance of burn-in to stabilize electrodes from the effects of electromigration and grain reorganization before use in CV measurements, by comparing with results obtained with as-deposited electrodes. Burn-in (or equivalently, annealing) of lithographic microelectrodes before use is of general importance to electrochemical sensing devices Full article
(This article belongs to the Special Issue Microfluidic Biosensing Platform)
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15 pages, 7850 KiB  
Article
Ultrathin PANI-Decorated, Highly Purified and Well Dispersed Array Cncs for Highly Sensitive HCHO Sensors
by Qingmin Hu, Zhiheng Ma, Jie Yang, Tiange Gao, Yue Wu, Zhe Dong, Xuyi Li, Wen Zeng, Shichao Zhao and Jiaqiang Xu
Chemosensors 2021, 9(10), 276; https://doi.org/10.3390/chemosensors9100276 - 28 Sep 2021
Cited by 6 | Viewed by 2379
Abstract
The flocculation of small surficial groups on pristine CNCs (carbon nanocoils) bundles limit their application. In this study, we designed and fabricated novel array CNCs with a surficial decoration of polyaniline (PANI) using in situ methods. Atomic layer deposition (ALD) and chemical vapor [...] Read more.
The flocculation of small surficial groups on pristine CNCs (carbon nanocoils) bundles limit their application. In this study, we designed and fabricated novel array CNCs with a surficial decoration of polyaniline (PANI) using in situ methods. Atomic layer deposition (ALD) and chemical vapor deposition (CVD) methods were employed to fabricate the highly pure array CNCs. The array CNCs decorated with ultra-thin PANI were confirmed by different characterizations. Furthermore, this material displayed a good performance in its detection of formaldehyde. The detection results showed that the CNCs coated with PANI had a low limit of detection of HCHO, as low as 500 ppb, and the sensor also showed good selectivity for other interfering gases, as well as good repeatability over many tests. Furthermore, after increasing the PANI loading on the surface of the CNCs, their detection performance exhibited a typical volcanic curve, and the value of the enthalpy was extracted by using the temperature-varying micro-gravimetric method during the process of detection of the formaldehyde molecules on the CNCs. The use of array CNCs with surficial decoration offers a novel method for the application of CNCs and could be extended to other applications, such as catalysts and energy conversion. Full article
(This article belongs to the Special Issue Recent Developments in Electrochemical Sensing)
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23 pages, 1535 KiB  
Review
Current State of Laser-Induced Fluorescence Spectroscopy for Designing Biochemical Sensors
by Adam Thomas Taylor and Edward P. C. Lai
Chemosensors 2021, 9(10), 275; https://doi.org/10.3390/chemosensors9100275 - 27 Sep 2021
Cited by 26 | Viewed by 7358
Abstract
Laser-induced fluorescence (LIF) has been a valuable analytical technique since the 1970s that has only been made more useful through advances in other scientific fields such as biochemistry. Moreover, advances in laser and detector technology have seen a decrease in LIF detector costs [...] Read more.
Laser-induced fluorescence (LIF) has been a valuable analytical technique since the 1970s that has only been made more useful through advances in other scientific fields such as biochemistry. Moreover, advances in laser and detector technology have seen a decrease in LIF detector costs and an increase in their ease of use. These changes have allowed for LIF technology to be widely adopted for various sensor designs in combination with advanced instruments. With advances in biochemistry necessitating the detection of complex metabolites, labelling with fluorescent chemical reagents may be necessary to improve detection sensitivity. Furthermore, advances made in fluorescent labeling technologies have allowed for the use of LIF in the detection of nanoparticles as well as for imaging techniques using nanoparticles as signal amplifiers. This technology has become invaluable in the detection of environmental pollutants, monitoring of biological metabolites, biological imaging, and cancer diagnosis, making it one of the most valuable analytical science techniques currently available. Full article
(This article belongs to the Special Issue Nanomaterials, Nanoreagents, Nanostructures and Nanolight Sources for Designing Novel Chemical and Biochemical Sensors)
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14 pages, 5044 KiB  
Article
Potentiometric C2H4-Selective Detection on Solid-State Sensors Activated with Bifunctional Catalytic Nanoparticles
by Fidel Toldra-Reig and Jose Manuel Serra
Chemosensors 2021, 9(10), 274; https://doi.org/10.3390/chemosensors9100274 - 27 Sep 2021
Cited by 4 | Viewed by 2249
Abstract
This work presents a solid-state ionic-based device to selectively detect C2H4 in car exhaust gases. The sensor consists of 8YSZ as the electrolyte and two electrodes: Fe0.7Cr1.3O3/8YSZ and LSM/8YSZ. The main aim of this [...] Read more.
This work presents a solid-state ionic-based device to selectively detect C2H4 in car exhaust gases. The sensor consists of 8YSZ as the electrolyte and two electrodes: Fe0.7Cr1.3O3/8YSZ and LSM/8YSZ. The main aim of this work is to optimize the catalytic behavior of the working electrode to C2H4 and reduce cross-sensitivity toward CO and H2O. Several catalyst nanoparticles were infiltrated to tailor C2H4 adsorption and electrochemical oxidation properties while diminishing adsorption and conversion of other gas components such as CO. The infiltrated metal catalysts were selected, taking into account both adsorption and redox properties. Infiltration of Ti or Al, followed by a second infiltration of Ni, enabled the selective detection of C2H4 with low cross-sensitivity toward CO and H2O in a moist gas environment. Further insight into potentiometric C2H4 sensing is achieved by electrochemical impedance analysis of the electrodes activated with bifunctional catalysts. Full article
(This article belongs to the Special Issue Gas Sensors: Simulation, Modeling, and Characterization)
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19 pages, 3015 KiB  
Article
Comprehensive Characterization of 76 Pharmaceuticals and Metabolites in Wastewater by LC-MS/MS
by Cristian Gómez-Canela, Sílvia Edo, Natalia Rodríguez, Gemma Gotor and Sílvia Lacorte
Chemosensors 2021, 9(10), 273; https://doi.org/10.3390/chemosensors9100273 - 24 Sep 2021
Cited by 28 | Viewed by 4111
Abstract
Wastewaters are considered one of the main sources of pollution in the aquatic environment as release a large number of contaminants every day. Emerging contaminants such as pharmaceuticals have special interest due to the high levels of consumption by the global population, their [...] Read more.
Wastewaters are considered one of the main sources of pollution in the aquatic environment as release a large number of contaminants every day. Emerging contaminants such as pharmaceuticals have special interest due to the high levels of consumption by the global population, their bioactive properties and because actual directives do not include the monitoring of pharmaceuticals. Moreover, it is well-known that pharmaceuticals can be degraded to metabolites or transformation products (TPs), which could be more toxic than the parental compound. In this study, we have developed an analytical method based on solid-phase extraction (SPE) and liquid chromatography coupled to tandem mass spectrometry (LC-MS/MS) to determine 76 highly consumed pharmaceuticals, including metabolites and TPs in wastewater effluents. In the 10 wastewaters analysed, the mean concentrations were in the µg L−1 levels, being mycophenolic acid, levodopa, ibuprofen, 4-aminoantypirine, losartan, amylmetacresol, amoxicillin, fluticasone, tramadol, budesonide, chlorpheniramine and diclofenac the pharmaceuticals with the highest concentrations. This study provides a comprehensive optimization on the MS conditions to determine pharmaceutical compounds and their metabolites and provides a spectral characterization to be used for the identification of these compounds in water. Full article
(This article belongs to the Collection Recent Trend in Chromatography for Pharmaceutical Analysis)
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13 pages, 5229 KiB  
Article
MagnetoPlasmonic Waves/HOMO-LUMO Free π-Electron Transitions Coupling in Organic Macrocycles and Their Effect in Sensing Applications
by Maria Grazia Manera, Gabriele Giancane, Simona Bettini, Ludovico Valli, Victor Borovkov, Adriano Colombelli, Daniela Lospinoso and Roberto Rella
Chemosensors 2021, 9(10), 272; https://doi.org/10.3390/chemosensors9100272 - 22 Sep 2021
Cited by 1 | Viewed by 2175
Abstract
Optical and magneto-optical surface plasmon resonance (MOSPR) characterization and preliminary sensing test onto single- and multi-layers of two organic macrocycles have been performed; TbPc2(OC11H21)8 phthalocyanine and CoCoPo2 porphyrin were deposited by the Langmuir-Schäfer (LS) technique [...] Read more.
Optical and magneto-optical surface plasmon resonance (MOSPR) characterization and preliminary sensing test onto single- and multi-layers of two organic macrocycles have been performed; TbPc2(OC11H21)8 phthalocyanine and CoCoPo2 porphyrin were deposited by the Langmuir-Schäfer (LS) technique onto proper Au/Co/Au magneto-optical transducers. Investigations of the MOSPR properties in Kretschmann configuration by angular modulation, gives us an indication about the potential discrimination of two organic macrocycles with absorption electronic transition in and out of the propagating plasmon energy spectral range. An improved molecular vapors sensitivity increase by the MOSPR sensing probe can be demonstrated depending on the overlap between the plasmonic probe energy and the absorption electronic transitions of the macrocycles under investigation. If the interaction between the plasmon energy and molecular HOMO-LUMO transition is preserved, a variation in the complex refractive index takes place. Under this condition, the magneto-plasmonic effect reported as 1/|MOSPR| signal allows us to increase the detection of molecules deposited onto the plasmonic transducer and their gas sensing capacity. The detection mechanism appears strongly enhanced if the Plasmon Wave/HOMO-LUMO transitions energy are in resonance. Under coupling conditions, a different volatile organic compounds (VOC) sensing capability has been demonstrated using n-butylamine as the trial molecule. Full article
(This article belongs to the Section Materials for Chemical Sensing)
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