Chemosensors

29 pages, 3233 KiB

Open AccessEditor’s ChoiceReview

Electrochemical vs. Optical Biosensors for Point-of-Care Applications: A Critical Review

by Seyedeh Rojin Shariati Pour, Donato Calabria, Afsaneh Emamiamin, Elisa Lazzarini, Andrea Pace, Massimo Guardigli, Martina Zangheri and Mara Mirasoli

Chemosensors 2023, 11(10), 546; https://doi.org/10.3390/chemosensors11100546 - 21 Oct 2023

Cited by 18 | Viewed by 4911

Abstract

Analytical chemistry applied to medical and diagnostic analysis has recently focused on the development of cost-effective biosensors able to monitor the health status or to assess the level of specific biomarkers that can be indicative of several diseases. The improvement of technologies relating [...] Read more.

Analytical chemistry applied to medical and diagnostic analysis has recently focused on the development of cost-effective biosensors able to monitor the health status or to assess the level of specific biomarkers that can be indicative of several diseases. The improvement of technologies relating to the possibility of the non-invasive sampling of biological fluids, as well as sensors for the detection of analytical signals and the computational capabilities of the systems routinely employed in everyday life (e.g., smartphones, computers, etc.), makes the complete integration of self-standing analytical devices more accessible. This review aims to discuss the biosensors that have been proposed in the last five years focusing on two principal detecting approaches, optical and electrochemical, which have been employed for quantifying different kinds of target analytes reaching detection limits below the clinical sample levels required. These detection principles applied to point-of-care (POC) devices have been extensively reported in literature, and even the limited examples found on the market are based on these strategies. This work will show the latest innovations considering the integration of optical and electrochemical detection with the most commonly reported analytical platforms for POC applications such as paper-based or wearable and implantable devices. Full article

(This article belongs to the Collection Electrochemical Biosensors for Medical Diagnosis)

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15 pages, 6254 KiB

Open AccessEditor’s ChoiceArticle

Signal Amplification for Detection of Nilutamide in Three-Dimensional Electrochemical Sensor Using Copper Metal–Organic Framework Decorated Carbon Nanofibers

by Elaiyappillai Elanthamilan and Sea-Fue Wang

Chemosensors 2023, 11(10), 544; https://doi.org/10.3390/chemosensors11100544 - 20 Oct 2023

Cited by 11 | Viewed by 2082

Abstract

The extensive use of antibiotics has rapidly spread antibiotic resistance, which poses significant health risks to humans. Unfortunately, despite this pressing issue, there is still a lack of a reliable on-site detection method for the residues of antibiotics, such as nilutamide (Nlu). Consequently, [...] Read more.

The extensive use of antibiotics has rapidly spread antibiotic resistance, which poses significant health risks to humans. Unfortunately, despite this pressing issue, there is still a lack of a reliable on-site detection method for the residues of antibiotics, such as nilutamide (Nlu). Consequently, there is an urgent need to develop and perfect such a detection method to effectively monitor and control antibiotic residues. In this study, the hydrothermal development of copper-metal-organic framework (Cu-MOF) polyhedrons on the functionalized carbon nanofiber (f-CNF) matrix allowed for the detection of Nlu in biological liquids via a sensitive amperometry technique. Further electrochemical detection of Nlu took place with the cyclic voltammetry (CV) technique Cu-MOF/f-CNF. Analytical and spectroscopic approaches were used to confirm the successful synthesis of Cu-MOF/f-CNF. The prepared material was decorated on the surface of GCE and performed as an electrochemical Nlu sensor, with a broad linear range of 0.01 to 141.4 μM and 2 nM as a lower limit of detection. In addition, the composites had a large surface area and many dedicated sites, which improved electrocatalysis. In practical applications, Cu-MOF/f-CNF/GCE provides a novel strategy for improving electrochemical activity by measuring Nlu concentrations in biological samples. Full article

(This article belongs to the Special Issue Electrochemical Sensors and Their Applications: A Theme Issue in Honor of Professor Richard G. Compton)

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16 pages, 6911 KiB

Open AccessEditor’s ChoiceArticle

Electro-Optical Nose for Indoor Air Quality Monitoring

by Víctor González, Félix Meléndez, Patricia Arroyo, Javier Godoy, Fernando Díaz, José Ignacio Suárez and Jesús Lozano

Chemosensors 2023, 11(10), 535; https://doi.org/10.3390/chemosensors11100535 - 11 Oct 2023

Cited by 5 | Viewed by 2484

Abstract

Nowadays, indoor air pollution is a major problem that affects human health. For that reason, measuring indoor air quality has an increasing interest. Electronic noses are low-cost instruments (compared with reference methods) capable of measuring air components and pollutants at different concentrations. In [...] Read more.

Nowadays, indoor air pollution is a major problem that affects human health. For that reason, measuring indoor air quality has an increasing interest. Electronic noses are low-cost instruments (compared with reference methods) capable of measuring air components and pollutants at different concentrations. In this paper, an electro-optical nose (electronic nose that includes optical sensors) with non-dispersive infrared sensors and metal oxide semiconductor sensors is used to measure gases that affect indoor air quality. To validate the developed prototype, different gas mixtures (CH₄ and CO₂) with variable concentrations and humidity values are generated to confirm the discrimination capabilities of the device. Principal Component Analysis (PCA) was used for dimensionality reduction purposes to show the measurements in a plot. Partial Least Squares Regression (PLS) was also performed to calculate the predictive capabilities of the device. PCA results using all the measurements from all the sensors obtained PC1 = 47% and PC2 = 10%; results are improved using only the relevant information of the sensors obtaining PC1 = 79% and PC2 = 9%. PLS results with CH₄ using only MOX sensors received an RMSE = 118.8. When using NDIR and MOX sensors, RMSE is reduced to 19.868; this tendency is also observed in CO₂ (RMSE = 116.35 with MOX and RMSE = 20.548 with MOX and NDIR). The results confirm that the designed electro-optical nose can detect different gas concentrations and discriminate between different mixtures of gases; also, a better correlation and dispersion is achieved. The addition of NDIR sensors gives better results in measuring specific gases, discrimination, and concentration prediction capabilities in comparison to electronic noses with metal oxide gas sensors. Full article

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

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12 pages, 2868 KiB

Open AccessEditor’s ChoiceCommunication

Detection of a Nerve Agent Simulant by a Fluorescent Sensor Array

by Rossella Santonocito, Mario Spina, Roberta Puglisi, Andrea Pappalardo, Nunzio Tuccitto and Giuseppe Trusso Sfrazzetto

Chemosensors 2023, 11(9), 503; https://doi.org/10.3390/chemosensors11090503 - 15 Sep 2023

Cited by 11 | Viewed by 2627

Abstract

Detection of nerve agents (NAs) gas in the environment through portable devices to protect people in case of emergencies still remains a challenge for scientists involved in this research field. Current detection strategies require the use of cumbersome, expensive equipment that is only [...] Read more.

Detection of nerve agents (NAs) gas in the environment through portable devices to protect people in case of emergencies still remains a challenge for scientists involved in this research field. Current detection strategies require the use of cumbersome, expensive equipment that is only accessible to specialized personnel. By contrast, emerging optical detection is one of the most promising strategies for the development of reliable, easy readout devices. However, the selectivity of the existing optical sensors needs to be improved. To overcome the lack of selectivity, the innovative strategy of the optical arrays is under evaluation due to the specific response, the ease of preparation, the portability of the equipment, and the possibility to use affordable detectors, such as smartphones, that are easily accessible to non-specialized operators. In this work, the first optical-based sensor array for the selective detection of gaseous dimethylmethylphosphonate (DMMP), a NAs simulant, is reported, employing a simple smartphone as a detector and obtaining remarkably efficient and selective detection. Full article

(This article belongs to the Special Issue Optical Chemical Sensors and Spectroscopy for Chemical Trace Element Detection)

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36 pages, 4557 KiB

Open AccessEditor’s ChoiceReview

Smartphone-Based Portable Bio-Chemical Sensors: Exploring Recent Advancements

by The Huy Bui, Balamurugan Thangavel, Mirkomil Sharipov, Kuangcai Chen and Joong Ho Shin

Chemosensors 2023, 11(9), 468; https://doi.org/10.3390/chemosensors11090468 - 22 Aug 2023

Cited by 21 | Viewed by 4849

Abstract

Traditionally, analytical chemistry and diagnosis relied on wet laboratories and skilled professionals utilizing sophisticated instruments for sample handling and analysis. However, with the development of novel materials and sensing techniques, there has been a significant shift towards the use of standalone sensors, allowing [...] Read more.

Traditionally, analytical chemistry and diagnosis relied on wet laboratories and skilled professionals utilizing sophisticated instruments for sample handling and analysis. However, with the development of novel materials and sensing techniques, there has been a significant shift towards the use of standalone sensors, allowing tests to be conducted on-site or even in real time, leading to cost- and time-efficiency. With their widespread adoption globally, smartphones have emerged as an ideal platform for such sensors, boasting extensive sensor capabilities, advanced processing power, and communication functionalities. Smartphone-based assays make use of optical and electrochemical sensors, utilizing built-in cameras, ambient light sensors, and other features for optical sensing, while the micro-USB port, Bluetooth, and wireless connection facilitate data transmission and analog voltage application for electrochemical sensing. Previous overview papers have explored smartphone-based sensing in specific domains; this review provides a comprehensive examination of recent advancements in smartphone-based sensors, encompassing both optical and electrochemical sensing methods. The review provides the fundamental principles of these sensors and their implementation using smartphones, showcases recent applications, and presents innovative designs that take advantage of the inherent functionalities and sensor capabilities of smartphones. The review concludes by offering an outlook on the prospects of smartphone-based sensing and includes a reflective section emphasizing the potential impact of sensors in chemical and biological analyses. This comprehensive resource aims to provide information to researchers and practitioners interested in using smartphones for cutting-edge analytical methodologies. Full article

(This article belongs to the Special Issue Application and Advance of Optical Immunosensors)

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15 pages, 2657 KiB

Open AccessEditor’s ChoiceArticle

Eco-Friendly, High-Performance Humidity Sensor Using Purple Sweet-Potato Peel for Multipurpose Applications

by Sheik Abdur Rahman, Shenawar Ali Khan, Shahzad Iqbal, Muhammad Muqeet Rehman and Woo Young Kim

Chemosensors 2023, 11(8), 457; https://doi.org/10.3390/chemosensors11080457 - 15 Aug 2023

Cited by 6 | Viewed by 2406

Abstract

Biomaterials offer great potential for enhancing the performance of humidity sensors, which play a critical role in controlling moisture levels across different applications. By utilizing environmentally friendly, sustainable, and cost-effective biomaterials, we can improve the manufacturing process of these sensors while reducing our [...] Read more.

Biomaterials offer great potential for enhancing the performance of humidity sensors, which play a critical role in controlling moisture levels across different applications. By utilizing environmentally friendly, sustainable, and cost-effective biomaterials, we can improve the manufacturing process of these sensors while reducing our environmental impact. In this study, we present a high-performance humidity sensor that utilizes purple sweet potato peel (PSPP) as both the substrate and sensing layer. The PSPP is chosen for its polar hydrophilic functional groups, as well as its environmentally friendly nature, sustainability, and cost-effectiveness. Remarkably, this humidity sensor does not require an external substrate. It exhibits a wide detection range of 0 to 85% relative humidity at various operating frequencies (100 Hz, 1 kHz, and 10 kHz) in ambient temperature, demonstrating its effectiveness in responding to different humidity levels. The sensor achieves a high sensitivity value of 183.23 pF/%RH and minimal hysteresis of only 5% at 10 kHz under ambient conditions. It also boasts rapid response and recovery times of 1 and 2 s, respectively, making it suitable for use in high-end electronic devices. Moreover, the sensor’s applications extend beyond environmental monitoring. It has proven effective in monitoring mouth and nasal breathing, indicating its potential for respiratory monitoring and noncontact proximity response. These findings suggest that sweet potato peel material holds great promise as a highly stable, non-toxic, biodegradable, cost-effective, and environmentally friendly option for various domains, including healthcare monitoring. Full article

(This article belongs to the Section Applied Chemical Sensors)

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12 pages, 1754 KiB

Open AccessEditor’s ChoiceArticle

Exploiting the Advantages of Ag/ITO/Enzyme Trapped Gel Layers to Develop a Highly Sensitive and Selective Fiber Optic Plasmonic Urea Sensor

by Sonika Sharma and Satyendra K. Mishra

Chemosensors 2023, 11(8), 421; https://doi.org/10.3390/chemosensors11080421 - 26 Jul 2023

Cited by 15 | Viewed by 1764

Abstract

The fabrication and characterization of a surface plasmon resonance (SPR)-based urea biosensor, with thin silver (Ag), ITO (In₂O₃: SnO₂), and enzyme-trapped gel over an unclad portion of plastic-clad silica fiber as a sensing element, is represented. The [...] Read more.

The fabrication and characterization of a surface plasmon resonance (SPR)-based urea biosensor, with thin silver (Ag), ITO (In₂O₃: SnO₂), and enzyme-trapped gel over an unclad portion of plastic-clad silica fiber as a sensing element, is represented. The working principle is to identify changes in the refractive index of the enzyme (urease) entrapped gel layer following the interaction with the incoming analyte. This interaction causes swelling and shrinkage of the gel layer, which alters the effective refractive index of the sensing layer. The wavelength interrogation method is used, and the optimized sensor probe is characterized by urea samples having different pH values. Scanning electron microscopy confirmed the uniformity of the silver layer over the unclad core of the fiber. The sensor operates from 0 to 160 mM of urea concentrations to cover the physiological concentration range of blood urea normally present in the human body. The sensitivity and limit of detection (LOD) offered by the sensor are marked 0.59387 nm/mM near zero concentration of the urea sample and 0.56 mM, respectively, along with the provisions of high stability, remote sensing, and online monitoring of urea. The proposed sensor has proven to be one of a kind due to its fast response time. Full article

(This article belongs to the Special Issue Advanced Bio-Chemical Sensors Based on Plasmonic Nanostructures)

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13 pages, 2784 KiB

Open AccessEditor’s ChoiceArticle

Application of the OECT-Based In Vivo Biosensor Bioristor in Fruit Tree Monitoring to Improve Agricultural Sustainability

by Filippo Vurro, Edoardo Marchetti, Manuele Bettelli, Luigi Manfrini, Adele Finco, Carlo Sportolaro, Nicola Coppedè, Nadia Palermo, Maria Grazia Tommasini, Andrea Zappettini and Michela Janni

Chemosensors 2023, 11(7), 374; https://doi.org/10.3390/chemosensors11070374 - 4 Jul 2023

Cited by 6 | Viewed by 2355

Abstract

Water scarcity is a major concern in agriculture worldwide. Fruit trees are severely affected by water deprivation in terms of growth, fruit yield, and quality. Plant monitoring combined with efficient irrigation is pivotal to achieve good quality standards and improve agricultural sustainability. This [...] Read more.

Water scarcity is a major concern in agriculture worldwide. Fruit trees are severely affected by water deprivation in terms of growth, fruit yield, and quality. Plant monitoring combined with efficient irrigation is pivotal to achieve good quality standards and improve agricultural sustainability. This study reports the use of in vivo sensing technology to monitor fruit tree species continuously, in real time and in vivo, through an Organic Electrochemical Transistor (OECT)-based biosensor called Bioristor. The sensor was applied to grapevines, apples, and kiwis, revealing its capability to trace the plant water status for the whole productive cycle. A correlation between the sensor response index (R) and environmental parameters such as air humidity and temperature were recorded for fruit species. The day/night oscillation of the ionic content in the transpiration stream varies during plant growth and fruit maturation and during severe drought stress. Bioristor promptly detected the occurrence of drought stress. The gate current (Igs) trend supports the reduction in the saturation of the system due to the lower water availability. The use of Bioristor-acquired indices can be used to improve precision irrigation techniques according to the real plant needs. Full article

(This article belongs to the Special Issue Recent Advances in Electrochemical Biosensors for Agricultural, Biological, and Environmental Applications)

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14 pages, 1657 KiB

Open AccessEditor’s ChoiceArticle

MoS₂@Au as Label for Sensitive Sandwich-Type Immunoassay of Neuron-Specific Enolase

by Yingying Wang, Huixin Wang, Yaliang Bai, Guanhui Zhao, Nuo Zhang, Yong Zhang, Yaoguang Wang and Hong Chi

Chemosensors 2023, 11(6), 349; https://doi.org/10.3390/chemosensors11060349 - 19 Jun 2023

Cited by 17 | Viewed by 1734

Abstract

Neuron-specific enolase (NSE) has gained extensive attention as a reliable target for detecting small cell carcinoma of lungs. In this paper, an electrochemical immunoassay method based on molybdenum disulfide (MoS₂) is proposed to detect NSE sensitively. By an in-situ growth method, [...] Read more.

Neuron-specific enolase (NSE) has gained extensive attention as a reliable target for detecting small cell carcinoma of lungs. In this paper, an electrochemical immunoassay method based on molybdenum disulfide (MoS₂) is proposed to detect NSE sensitively. By an in-situ growth method, MoS₂ and Au nanoclusters (Au NCs) were composited to form a MoS₂@Au nanozyme, and then the secondary antibodies were modified. Primary antibodies were immobilized on amino-reduced graphene oxides to capture NSE. The flower-like MoS₂ nanozyme provided abundant sites to load Au NCs and catalyze the decomposition of H₂O₂, which were beneficial to amplify an amperometric response as well as build up sensitivity. Under optimum conditions, the detection range of this strategy was 0.1 pg·mL⁻¹–10 ng·mL⁻¹ and the limit of detection was 0.05 pg·mL⁻¹. This sensing strategy achieved the prospect of sensitively detecting NSE. Moreover, the prepared electrochemical immunosensor provides a theoretical basis and technical support for the detection of other disease markers. Full article

(This article belongs to the Special Issue Bionic Recognition and Biosensors: A Theme Issue in Honor of Professor Hong-Yuan Chen)

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13 pages, 2661 KiB

Open AccessEditor’s ChoiceArticle

Layer-by-Layer Films of Silsesquioxane and Nickel(II) Tetrasulphophthalocyanine as Glucose Oxidase Platform Immobilization: Amperometric Determination of Glucose in Kombucha Beverages

by João Paulo Winiarski, Douglas José de Melo, Edson Roberto Santana, Cleverson Siqueira Santos, Cliciane Guadalupe de Jesus, Sérgio Toshio Fujiwara, Karen Wohnrath and Christiana Andrade Pessôa

Chemosensors 2023, 11(6), 346; https://doi.org/10.3390/chemosensors11060346 - 14 Jun 2023

Cited by 11 | Viewed by 1510

Abstract

This paper describes the development of a novel glucose biosensor through the layer-by-layer technique (LbL). The self-assembled architectures were composed of a positive-charged silsesquioxane polyelectrolyte, 3-n-propylpyridinium silsesquioxane chloride (SiPy⁺Cl⁻), nickel (II) tetrassulphophthalocyanine (NiTsPc), and a conductive surface [...] Read more.

This paper describes the development of a novel glucose biosensor through the layer-by-layer technique (LbL). The self-assembled architectures were composed of a positive-charged silsesquioxane polyelectrolyte, 3-n-propylpyridinium silsesquioxane chloride (SiPy⁺Cl⁻), nickel (II) tetrassulphophthalocyanine (NiTsPc), and a conductive surface of FTO (fluor tin oxide). The construction of the biosensor was influenced by the isoelectric point (pI) of the glucose oxidase enzyme (GOx), which allowed electrostatic interaction between the outer layer of the silsesquioxane film and the enzyme. The architecture of modified electrode GOx/(SiPy⁺Cl⁻/NiTsPc)_5.5/FTO was confirmed by UV-Vis, FTIR, and chronoamperometry techniques using different immobilization methods of GOx. Among the studied methods, a higher variation of current was observed for the modified electrode formed by mixed LbL films of SiPy⁺Cl⁻ and NiTsPc and the enzyme immobilized by drop coating. The stability and reproducibility of the biosensor were verified when the last layer containing the enzyme was coated with 0.2% Nafion^® polymer. Under these conditions, a linear response for glucose was obtained in the concentration range of 0.2 to 1.6 mmol L⁻¹ (R² = 0.991) with a limit of detection of 0.022 mmol L⁻¹. The proposed biosensor was applied to quantify glucose in two different samples of kombucha juices with accuracy, allowing the glucose content of the healthy beverages to be estimated. Full article

(This article belongs to the Special Issue Advanced Nanomaterials-Based (Bio)sensors for Electrochemical Detection and Analysis)

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28 pages, 2119 KiB

Open AccessEditor’s ChoiceReview

The Role of Nano-Sensors in Breath Analysis for Early and Non-Invasive Disease Diagnosis

by Nefeli Lagopati, Theodoros-Filippos Valamvanos, Vaia Proutsou, Konstantinos Karachalios, Natassa Pippa, Maria-Anna Gatou, Ioanna-Aglaia Vagena, Smaragda Cela, Evangelia A. Pavlatou, Maria Gazouli and Efstathios Efstathopoulos

Chemosensors 2023, 11(6), 317; https://doi.org/10.3390/chemosensors11060317 - 24 May 2023

Cited by 12 | Viewed by 5577

Abstract

Early-stage, precise disease diagnosis and treatment has been a crucial topic of scientific discussion since time immemorial. When these factors are combined with experience and scientific knowledge, they can benefit not only the patient, but also, by extension, the entire health system. The [...] Read more.

Early-stage, precise disease diagnosis and treatment has been a crucial topic of scientific discussion since time immemorial. When these factors are combined with experience and scientific knowledge, they can benefit not only the patient, but also, by extension, the entire health system. The development of rapidly growing novel technologies allows for accurate diagnosis and treatment of disease. Nanomedicine can contribute to exhaled breath analysis (EBA) for disease diagnosis, providing nanomaterials and improving sensing performance and detection sensitivity. Through EBA, gas-based nano-sensors might be applied for the detection of various essential diseases, since some of their metabolic products are detectable and measurable in the exhaled breath. The design and development of innovative nanomaterial-based sensor devices for the detection of specific biomarkers in breath samples has emerged as a promising research field for the non-invasive accurate diagnosis of several diseases. EBA would be an inexpensive and widely available commercial tool that could also be used as a disease self-test kit. Thus, it could guide patients to the proper specialty, bypassing those expensive tests, resulting, hence, in earlier diagnosis, treatment, and thus a better quality of life. In this review, some of the most prevalent types of sensors used in breath-sample analysis are presented in parallel with the common diseases that might be diagnosed through EBA, highlighting the impact of incorporating new technological achievements in the clinical routine. Full article

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

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16 pages, 5203 KiB

Open AccessEditor’s ChoiceArticle

Preparation of Reduced Graphene Oxide Sheets with Large Surface Area and Porous Structure for High-Sensitivity Humidity Sensor

by Seo Jin Kim, Hong Jun Park, Eun Seop Yoon and Bong Gill Choi

Chemosensors 2023, 11(5), 276; https://doi.org/10.3390/chemosensors11050276 - 4 May 2023

Cited by 9 | Viewed by 2499

Abstract

Humidity sensors provide environmental conditions suitable for several applications. However, they suffer from a limited reliable range originating from the low electrical conductivity and low water-sensitive sites of humidity-sensing materials. In this study, we developed high-sensitivity humidity sensors based on holey-reduced graphene oxide [...] Read more.

Humidity sensors provide environmental conditions suitable for several applications. However, they suffer from a limited reliable range originating from the low electrical conductivity and low water-sensitive sites of humidity-sensing materials. In this study, we developed high-sensitivity humidity sensors based on holey-reduced graphene oxide (HRGO) with a large surface area (274.5 m²/g) and an abundant pore structure. HRGO was prepared via the H₂O₂-etching-reaction-assisted hydrothermal processing of graphene oxide sheets. The resulting humidity sensor exhibited high sensitivity (−0.04317 log Z/%RH, R² = 0.9717), a fast response time (<3 s), and long-term stability over 28 days. The impedance responses of the humidity sensor were almost similar between the mechanically standard and bent states. Furthermore, electrochemical impedance spectroscopy was performed to understand the humidity-sensing mechanism of the HRGO materials. Full article

(This article belongs to the Special Issue Recent Advances in Electrochemical Biosensors for Agricultural, Biological, and Environmental Applications)

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15 pages, 15419 KiB

Open AccessEditor’s ChoiceArticle

Perovskite-Structured NiTiO₃ Modified NiO Gas Sensor for Xylene Detection

by Liyun Qin, Hongliang Gao and Fanli Meng

Chemosensors 2023, 11(5), 264; https://doi.org/10.3390/chemosensors11050264 - 29 Apr 2023

Cited by 15 | Viewed by 2054

Abstract

Xylene gas is highly toxic, can irritate the skin, and is also very harmful to the body. Therefore, it is necessary to prepare sensors that can accurately detect xylene. In this paper, NiTiO₃ nanoparticles were synthesized by the hydrothermal method and used [...] Read more.

Xylene gas is highly toxic, can irritate the skin, and is also very harmful to the body. Therefore, it is necessary to prepare sensors that can accurately detect xylene. In this paper, NiTiO₃ nanoparticles were synthesized by the hydrothermal method and used to modify NiO, and a NiTiO₃-modified NiO (NiTiO₃-NiO) nanosheet material was successfully prepared. Its microstructure and internal composition were observed and analyzed by various characterization methods. When detecting 100 ppm xylene gas at the optimum temperature, comparing the response level of the NiTiO₃-NiO sensor with that of a pure nickel oxide sensor, the former was 20 times that of the latter, and the sensitivity was greatly improved. In a 100 ppm xylene gas environment, the response level of the sensor reached 21, the minimum detection limit was 1 ppm, and the recovery time was 135.75 s. NiTiO₃ is a perovskite-structured material, with many active sites and good catalytic properties that promote redox reactions. Full article

(This article belongs to the Special Issue Application and Advance of Gas Sensors)

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17 pages, 5047 KiB

Open AccessEditor’s ChoiceArticle

MXene/NiO Composites for Chemiresistive-Type Room Temperature Formaldehyde Sensor

by Baoyu Huang, Xinwei Tong, Xiangpeng Zhang, Qiuxia Feng, Marina N. Rumyantseva, Jai Prakash and Xiaogan Li

Chemosensors 2023, 11(4), 258; https://doi.org/10.3390/chemosensors11040258 - 21 Apr 2023

Cited by 17 | Viewed by 3597

Abstract

In this work, MXene/NiO-composite-based formaldehyde (HCHO) sensing materials were successfully synthesized by an in situ precipitation method. The heterostructures between the MXene and NiO nanoparticles were verified by transmission electron microscopy (TEM), X-ray diffraction (XRD), and X-ray photoelectron spectroscopy (XPS). The HCHO sensing [...] Read more.

In this work, MXene/NiO-composite-based formaldehyde (HCHO) sensing materials were successfully synthesized by an in situ precipitation method. The heterostructures between the MXene and NiO nanoparticles were verified by transmission electron microscopy (TEM), X-ray diffraction (XRD), and X-ray photoelectron spectroscopy (XPS). The HCHO sensing performance of the MXene/NiO-based chemiresistive-type sensors was investigated. Compared to pure MXene and NiO materials, the sensing performance of the MXene/NiO-P2-based sensor to HCHO gas at room temperature was significantly enhanced by the formation of MXene/NiO heterojunctions. The response of the MXene/NiO-P2 sensor to 50 ppm HCHO gas was 8.8, which was much higher than that of the pure MXene and NiO. At room temperature, the detectable HCHO concentration of the MXene/NiO-P2-based sensor was 1 ppm, and the response and recovery time to 2 ppm HCHO was 279 s and 346 s, respectively. The MXene/NiO-P2 sensor also exhibited a good selectivity and a long-term stability to HCHO gas for 56 days. The in situ Fourier transform infrared (FTIR) spectra of the MXene/NiO-P2 sensor, when exposed to HCHO gas at different times, were investigated to verify the adsorption reaction products of HCHO molecules. Full article

(This article belongs to the Special Issue Low-Cost and High-Performance Gas Sensors: Materials, Design and Application)

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46 pages, 5210 KiB

Open AccessEditor’s ChoiceReview

Electrochemical Sweat Sensors

by Emanuel Bilbao, Octavio Garate, Theo Rodríguez Campos, Mariano Roberti, Mijal Mass, Alex Lozano, Gloria Longinotti, Leandro Monsalve and Gabriel Ybarra

Chemosensors 2023, 11(4), 244; https://doi.org/10.3390/chemosensors11040244 - 14 Apr 2023

Cited by 11 | Viewed by 5589

Abstract

Sweat analysis by means of minimally invasive wearable sensors is considered a potentially disruptive method for assessing clinical parameters, with exciting applications in early medical diagnostics and high-performance sports. Electrochemical sensors and biosensors are especially attractive because of the possibility of the electronic [...] Read more.

Sweat analysis by means of minimally invasive wearable sensors is considered a potentially disruptive method for assessing clinical parameters, with exciting applications in early medical diagnostics and high-performance sports. Electrochemical sensors and biosensors are especially attractive because of the possibility of the electronic integration of wearable devices. In this article, we review several aspects regarding the potentialities and present limitations of electrochemical sweat (bio)sensors, including: the main target analytes and their relationships with clinical conditions; most usual electrochemical techniques of transduction used according to the nature of the target analytes; issues connected to the collection of representative sweat samples; aspects regarding the associated, miniaturized electronic instrumentation used for signal processing and communication; and signal processing by machine learning. Full article

(This article belongs to the Special Issue Electrochemical Detection: Analytical and Biological Challenges)

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20 pages, 4647 KiB

Open AccessEditor’s ChoiceArticle

Flexible Miniaturized Electrochemical Sensors Based on Multiwalled Carbon Nanotube-Chitosan Nanomaterial for Determination of Nitrite in Soil Solutions

by Ana-Maria Gurban, Lucian-Gabriel Zamfir, Petru Epure, Ioana-Raluca Șuică-Bunghez, Raluca Mădălina Senin, Maria-Luiza Jecu, Maria Lorena Jinga and Mihaela Doni

Chemosensors 2023, 11(4), 224; https://doi.org/10.3390/chemosensors11040224 - 5 Apr 2023

Cited by 15 | Viewed by 2574

Abstract

Flexible screen-printed electrodes (SPE) were modified in a simple manner with different composite nanomaterials based on carbon allotropes, polymers, and metallic nanoparticles, for amperometric detection of nitrites in soil. Multiwalled carbon nanotubes (MWCNT), chitosan (CS), silver nanoparticles (AgNPs), 1,8-diaminonaphthalene (1,8-DAN), and a sol-gel [...] Read more.

Flexible screen-printed electrodes (SPE) were modified in a simple manner with different composite nanomaterials based on carbon allotropes, polymers, and metallic nanoparticles, for amperometric detection of nitrites in soil. Multiwalled carbon nanotubes (MWCNT), chitosan (CS), silver nanoparticles (AgNPs), 1,8-diaminonaphthalene (1,8-DAN), and a sol-gel (SG) matrix were used for modification of the carbon paste working electrodes. Sensitive and selective detection of nitrite was achieved by using a MWCNT-CS-modified sensor, in acetate buffer at pH 5, at an applied potential of 0.58 V vs. Ag/AgCl. The MWCNT-CS-based sensor displayed a specific sensitivity of 204.4 mA·M⁻¹·cm⁻², with a detection limit of 2.3 µM (S/N = 3) in a linear range up to 1.7 mM, showing good stability, reproducibility, and selectivity towards other interfering species. A miniaturized portable system using the developed flexible electrochemical MWCNT-CS-based sensors was dedicated for the detection of nitrite in different samples of soil solutions extracted by using suction lysimeters. Full article

(This article belongs to the Special Issue Carbon Nanomaterials and Related Materials for Sensing Applications)

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12 pages, 3045 KiB

Open AccessEditor’s ChoiceCommunication

Ultra-Low Detection of Perfluorooctanoic Acid Using a Novel Plasmonic Sensing Approach Combined with Molecularly Imprinted Polymers

by Rosalba Pitruzzella, Francesco Arcadio, Chiara Perri, Domenico Del Prete, Giovanni Porto, Luigi Zeni and Nunzio Cennamo

Chemosensors 2023, 11(4), 211; https://doi.org/10.3390/chemosensors11040211 - 26 Mar 2023

Cited by 10 | Viewed by 3471

Abstract

In this work, a novel optical fiber sensor system for ultra-low perfluorooctanoic acid (PFOA) detection in aqueous solutions is proposed. It is based on the connection, in series, of two different plastic optical fiber (POF) platforms: the first is a chemical chip realized [...] Read more.

In this work, a novel optical fiber sensor system for ultra-low perfluorooctanoic acid (PFOA) detection in aqueous solutions is proposed. It is based on the connection, in series, of two different plastic optical fiber (POF) platforms: the first is a chemical chip realized by using a D-shaped POF with microholes filled with a specific molecularly imprinted polymer (MIP); the second is a typical surface plasmon resonance (SPR) sensor based on a D-shaped POF. In particular, the MIP-based chemical chip was used to launch the light inside the SPR–POF chip to change the SPR phenomenon by exploiting the PFOA–MIP interaction in the microholes. At first, experimental results were performed in water to demonstrate the applicability of the proposed sensing approach for measuring PFOA (or C8) in a concentration range of 1 ppt to 750 ppt, obtaining an ultra-low limit of detection (LOD) equal to about 0.81 ppt. Then, experimental results were carried out in simulated seawater to implement a complex matrix. The obtained results denoted a slight matrix effect, paving the way for the applicability of the proposed chemical sensing mechanism in several aqueous solutions. Full article

(This article belongs to the Section Optical Chemical Sensors)

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25 pages, 6186 KiB

Open AccessEditor’s ChoiceReview

Electrospun Nanofibers as Chemosensors for Detecting Environmental Pollutants: A Review

by Yutong Du, Deng-Guang Yu and Tao Yi

Chemosensors 2023, 11(4), 208; https://doi.org/10.3390/chemosensors11040208 - 25 Mar 2023

Cited by 33 | Viewed by 5081

Abstract

Electrospun nanofibers have shown their advantages for applications in a wide variety of scientific fields thanks to their unique properties. Meanwhile, electrospinning is closely following the fast development of nano science and nanotechnology to move forward to smaller (pico-technology), more complicated nanostructures/nanodevices and [...] Read more.

Electrospun nanofibers have shown their advantages for applications in a wide variety of scientific fields thanks to their unique properties. Meanwhile, electrospinning is closely following the fast development of nano science and nanotechnology to move forward to smaller (pico-technology), more complicated nanostructures/nanodevices and more order (all kinds of nano arrays). Particularly, multiple-fluid electrospinning has the strong capability of creating nanostructures from a structural spinneret in a single-step and a straightforward “top-down” manner, holding great promise for creation on a large scale. This review is just to conclude the state-of-art studies on the related topics and also point out that the future directions of environmental detection require chemosensors, while the improvement of sensors requires new chemically synthesized functional substances, new nanostructured materials, application convenience, and functional integration or synergy. Based on the developments of electrospinning, more and more possibilities can be drawn out for detecting environmental pollutants with electrospun nanostructures as the strong support platform. Full article

(This article belongs to the Special Issue Chemical Sensors and Analytical Methods for Environmental Monitoring)

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24 pages, 2016 KiB

Open AccessEditor’s ChoiceArticle

Miniaturized NIR Spectrometers in a Nutshell: Shining Light over Sources of Variance

by Giulia Gorla, Paolo Taborelli, Hawbeer Jamal Ahmed, Cristina Alamprese, Silvia Grassi, Ricard Boqué, Jordi Riu and Barbara Giussani

Chemosensors 2023, 11(3), 182; https://doi.org/10.3390/chemosensors11030182 - 9 Mar 2023

Cited by 10 | Viewed by 2992

Abstract

The increasing portability and accessibility of miniaturized NIR spectrometers are promoting the spread of in-field and online applications. Alongside the successful outcomes, there are also several problems related to the acquisition strategies for each instrument and to experimental factors that can influence the [...] Read more.

The increasing portability and accessibility of miniaturized NIR spectrometers are promoting the spread of in-field and online applications. Alongside the successful outcomes, there are also several problems related to the acquisition strategies for each instrument and to experimental factors that can influence the collected signals. An insightful investigation of such factors is necessary and could lead to advancements in experimental set-up and data modelling. This work aimed to identify variation sources when using miniaturized NIR sensors and to propose a methodology to investigate such sources based on a multivariate method (ANOVA—Simultaneous Component Analysis) that considers the effects and interactions between them. Five different spectrometers were chosen for their different spectroscopic range and technical characteristics, and samples of worldwide interest were chosen as the case study. Comparing various portable sensors is interesting since results could significantly vary in the same application, justifying the idea that this kind of spectrometer is not to be treated as a general class of instruments. Full article

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

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12 pages, 2169 KiB

Open AccessEditor’s ChoiceArticle

Aggregation-Induced Emission-Active Iridium(III) Complexes for Sensing Picric Acid in Water

by Ping He, Yan Chen, Xiao-Na Li, Ying-Ying Yan and Chun Liu

Chemosensors 2023, 11(3), 177; https://doi.org/10.3390/chemosensors11030177 - 6 Mar 2023

Cited by 11 | Viewed by 2210

Abstract

Herein, two new iridium(III) complexes, namely Ir2 and Ir3, with a phenyl or triphenylamine (TPA) moiety at the 4-position of the phenyl ring at 2-phenylbenzothiazole, have been synthesized, and their emission properties have been studied systematically compared with the non-substituted complex Ir1 [...] Read more.

Herein, two new iridium(III) complexes, namely Ir2 and Ir3, with a phenyl or triphenylamine (TPA) moiety at the 4-position of the phenyl ring at 2-phenylbenzothiazole, have been synthesized, and their emission properties have been studied systematically compared with the non-substituted complex Ir1. These three complexes exhibit aggregation-induced emission (AIE) in H₂O/CH₃CN. The TPA-substituted complex Ir3 shows the highest AIE activity. All complexes can be used as sensors to detect picric acid (PA) in water. The Stern–Volmer constant (K_SV) of Ir3 for the detection of PA was determined to be 1.96 × 10⁶ M⁻¹, with a low limit of detection of 2.52 nM. Proton nuclear magnetic resonance spectra, high-resolution mass spectrometry analysis, and density function theory calculations confirm that the emission quenching mechanism of Ir3 is caused by photo-induced electron transfer. Furthermore, the efficient detection of PA in natural water proves that Ir1–Ir3 can be used as promising sensors in the natural environment. These results suggest that the AIE-active iridium(III) complexes can be used to detect PA under environment-friendly conditions. Full article

(This article belongs to the Special Issue 10th Anniversary of Chemosensors—Section 'Materials for Chemical Sensing')

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13 pages, 3752 KiB

Open AccessEditor’s ChoiceArticle

An Accessible Yarn-Based Sensor for In-Field Detection of Succinylcholine Poisoning

by Victor Ong, Nicholas R. Cortez, Ziru Xu, Farbod Amirghasemi, Mohamed K. Abd El-Rahman and Maral P. S. Mousavi

Chemosensors 2023, 11(3), 175; https://doi.org/10.3390/chemosensors11030175 - 4 Mar 2023

Cited by 4 | Viewed by 2403

Abstract

Succinylcholine (SUX) is a clinical anesthetic that induces temporary paralysis and is degraded by endogenous enzymes within the body. In high doses and without respiratory support, it results in rapid and untraceable death by asphyxiation. A potentiometric thread-based method was developed for the [...] Read more.

Succinylcholine (SUX) is a clinical anesthetic that induces temporary paralysis and is degraded by endogenous enzymes within the body. In high doses and without respiratory support, it results in rapid and untraceable death by asphyxiation. A potentiometric thread-based method was developed for the in-field and rapid detection of SUX for forensic use. We fabricated the first solid-contact SUX ion-selective electrodes from cotton yarn, a carbon black ink, and a polymeric ion-selective membrane. The electrodes could selectively measure SUX in a linear range of 1 mM to 4.3

μ

M in urine, with a Nernstian slope of 27.6 mV/decade. Our compact and portable yarn-based SUX sensors achieved 94.1% recovery at low concentrations, demonstrating feasibility in real-world applications. While other challenges remain, the development of a thread-based ion-selective electrode for SUX detection shows that it is possible to detect this poison in urine and paves the way for other low-cost, rapid forensic diagnostic devices. Full article

(This article belongs to the Special Issue Electrochemical Sensors and Their Applications: A Theme Issue in Honor of Professor Richard G. Compton)

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14 pages, 5608 KiB

Open AccessEditor’s ChoiceArticle

PEDOT:PSS/PEDOT Film Chemiresistive Sensors for Hydrogen Peroxide Vapor Detection under Ambient Conditions

by Xiaowen Xie, Nan Gao, Ling Zhu, Matthew Hunter, Shuai Chen and Ling Zang

Chemosensors 2023, 11(2), 124; https://doi.org/10.3390/chemosensors11020124 - 7 Feb 2023

Cited by 15 | Viewed by 2749

Abstract

Hydrogen peroxide (aqueous solution of H₂O₂) is one of the most used reagents i n medical sterilization, environmental disinfection, food storage, and other fields. However, hydrogen peroxide has the potential to cause serious harm to biological health and environmental [...] Read more.

Hydrogen peroxide (aqueous solution of H₂O₂) is one of the most used reagents i n medical sterilization, environmental disinfection, food storage, and other fields. However, hydrogen peroxide has the potential to cause serious harm to biological health and environmental safety. There are many methods (especially electrochemistry) for H₂O₂ detection in liquid phase systems, but a lack of methods for vapor detection. This is due to its colorless and tasteless nature, as well as the oxidative activity of the molecule and its coexistence with humidity. In this study, poly(3,4-ethylenedioxythiophene):polystyrene sulfonate (PEDOT:PSS), one of the most commercially successful and widely used conductive polymers, was employed to fabricate an all-organic chemiresistive sensor for simple, real-time, and on-site sensing of hydrogen peroxide vapor (HPV) at room temperature. In comparison with pristine PEDOT:PSS film, the PEDOT:PSS/PEDOT film was prepared by in situ electrochemical polymerization. Upon exposure to different concentrations of HPV, it was found that the hydrophobic and porous PEDOT layer could weaken the interference of humidity in HPV sensing, resulting in a more sensitive and accurate response. At 1.0 ppm HPV concentration, the resistance signal response was increased by nearly 89% compared with the pristine PEDOT:PSS film. This PEDOT-film-based chemiresistive sensor showcases the possibility for further development of nonenzymatic HPV monitoring technology. Full article

(This article belongs to the Special Issue 10th Anniversary of Chemosensors—Section 'Materials for Chemical Sensing')

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17 pages, 5695 KiB

Open AccessEditor’s ChoiceArticle

Pyrene-Based Fluorescent Probe for “Off-on-Off” Sequential Detection of Cu²⁺ and CN⁻ with HeLa Cells Imaging

by Muthaiah Shellaiah, Parthiban Venkatesan, Natesan Thirumalaivasan, Shu-Pao Wu and Kien-Wen Sun

Chemosensors 2023, 11(2), 115; https://doi.org/10.3390/chemosensors11020115 - 4 Feb 2023

Cited by 32 | Viewed by 3249

Abstract

The novel pyrene-appended Schiff base probe L with aggregation-induced emissions (AIE) relevant to an increase in water fractions (0–90%) is synthesized and applied in sequentially detecting Cu²⁺ and CN⁻. The pyrene-based probe L firstly induces the excimer formation in the [...] Read more.

The novel pyrene-appended Schiff base probe L with aggregation-induced emissions (AIE) relevant to an increase in water fractions (0–90%) is synthesized and applied in sequentially detecting Cu²⁺ and CN⁻. The pyrene-based probe L firstly induces the excimer formation in the presence of Cu²⁺. However, the process can be reversed by sequentially adding CN⁻, which is demonstrated using the fluorescence “Off-On-Off” response in semi-aqueous media ethanol water (v/v = 7/3) under physiological pH (5 mM HEPES, pH 7.0). The Job’s plot, mass analysis, ¹H NMR titrations, and density functional theory (DFT) interrogations confirm the 2:1 stoichiometry of excimer complex L–Cu²⁺-L*, preferential binding atoms, and CN⁻ tuned complex reversibility. Based on the photoluminescence (PL) titration, the association constant of L to Cu²⁺ is determined as 4.95 × 10⁶ M⁻¹. From standard deviation and linear fittings, the detection limits (LODs) of Cu²⁺ and CN⁻ are estimated as 219 nM and 580 nM, respectively. The practicality of Cu²⁺ and CN⁻ detection is demonstrated using a TLC plate and a blended polymer membrane through which significant color changes under a UV lamp can be monitored. Moreover, utility of the designed probe L towards biological application with low toxicity is demonstrated by detecting Cu²⁺ and CN⁻ inside HeLa cells. The responses of the probe to Cu(II) ions were also verified using living HeLa cells imaging. Full article

(This article belongs to the Special Issue Chemosensors for Ion Detection)

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23 pages, 4368 KiB

Open AccessEditor’s ChoiceReview

Engineering Rational SERS Nanotags for Parallel Detection of Multiple Cancer Circulating Biomarkers

by Zhipeng Zhang, Rui Guan, Junrong Li and Yao Sun

Chemosensors 2023, 11(2), 110; https://doi.org/10.3390/chemosensors11020110 - 3 Feb 2023

Cited by 17 | Viewed by 4153

Abstract

Precision cancer medicine necessitates a personalized treatment plan for each individual patient. Given cancer’s heterogeneity and dynamic nature, the plot of patient-specific signatures composed of multiple cancer circulating biomarkers is useful to reveal the complete tumor landscape for guiding precision medicine. As an [...] Read more.

Precision cancer medicine necessitates a personalized treatment plan for each individual patient. Given cancer’s heterogeneity and dynamic nature, the plot of patient-specific signatures composed of multiple cancer circulating biomarkers is useful to reveal the complete tumor landscape for guiding precision medicine. As an emerging new technology, surface-enhanced Raman scattering (SERS) shows the intrinsic advantage of performing multiplexed detection with the extremely narrow Raman spectral line widths. In this review, we first discuss the design principle of SERS nanotags to enable the detection of multiple circulating biomarkers, highlighting the important roles of plasmonic nanostructures and triple bond-modulated Raman reporters. Following this, we detail the use of isotropic and anisotropic nanostructures as SERS enhancement substrates for amplifying Raman signals in multi-biomarker detection. Furthermore, we present the triple bond-modulated molecules as Raman reporters in SERS nanotags to expand the multiplexing capability for biomarker measurements. Finally, we offer critical insights into the challenges and perspectives of SERS nanotags for cancer diagnosis, particularly from the aspect of future clinical transition. It is expected that this review can facilitate the design of more functional SERS nanotags with high sensitivity and multiplexing capability to assist early and accurate cancer screening. We also believe our review will be of interest in the fields of molecular imaging, biomedicine, and analytical chemistry. Full article

(This article belongs to the Collection Advances of Chemical and Biosensors in China)

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37 pages, 5976 KiB

Open AccessEditor’s ChoiceReview

Screen-Printed Electrodes: Fabrication, Modification, and Biosensing Applications

by Giti Paimard, Ehsan Ghasali and Mireia Baeza

Chemosensors 2023, 11(2), 113; https://doi.org/10.3390/chemosensors11020113 - 3 Feb 2023

Cited by 72 | Viewed by 16989

Abstract

As electrochemical measuring instruments, screen-printed electrodes (SPEs) are constructed via a technology called thick film deposition onto plastic or ceramic substrates, allowing for simple, inexpensive, and rapid on-site analysis with high reproducibility, sensitivity, and accuracy. Numerous substances such as gold, silver, platinum, and [...] Read more.

As electrochemical measuring instruments, screen-printed electrodes (SPEs) are constructed via a technology called thick film deposition onto plastic or ceramic substrates, allowing for simple, inexpensive, and rapid on-site analysis with high reproducibility, sensitivity, and accuracy. Numerous substances such as gold, silver, platinum, and carbon are applied for electrode construction, enabling the analyst to design the best device based on its purpose to determine an analyte’s selectivity and sensitivity. Thus, in the current review, we report the latest results and analyses conducted over the past eight years (2015–2022) on the expansion of SPE electrochemical biosensors, including aptasensors, immunosensors, DNA sensors, and enzymatic biosensors. Such expansion has resulted in new possibilities for the identification, distinction, and quantification of biocompounds, drugs, enzymes, etc. Therefore, in this paper, we review the role of different nanomaterials in manufacturing on-screen electrode methods as well as strategies for the future stable diagnosis of biorecognition elements. Full article

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

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32 pages, 6494 KiB

Open AccessEditor’s ChoiceReview

Fluorescence Modulation by Amines: Mechanistic Insights into Twisted Intramolecular Charge Transfer (TICT) and Beyond

by Cheng Chen and Chong Fang

Chemosensors 2023, 11(2), 87; https://doi.org/10.3390/chemosensors11020087 - 23 Jan 2023

Cited by 26 | Viewed by 4590

Abstract

Amine groups are common constituents of organic dyes and play important roles in tuning fluorescence properties. In particular, intensive research works have demonstrated the tendency and capabilities of amines in influencing chromophore brightness. Such properties have been explained by multiple mechanisms spanning from [...] Read more.

Amine groups are common constituents of organic dyes and play important roles in tuning fluorescence properties. In particular, intensive research works have demonstrated the tendency and capabilities of amines in influencing chromophore brightness. Such properties have been explained by multiple mechanisms spanning from twisted intramolecular charge transfer (TICT) to the energy gap law and beyond, which introduce additional nonradiative energy dissipation pathways. In this review, we aim to provide a focused overview of the mechanistic insights mainly for the TICT mechanism, accompanied by a few other less common or influential fluorescence quenching mechanisms in the amine-containing fluorescent molecules. Various aspects of current scientific findings including the rational design and synthesis of organic chromophores, theoretical calculations, steady-state and time-resolved electronic and vibrational spectroscopies are reviewed. These in-depth understandings of how the amine groups with diverse chemical structures at various atomic sites affect excited-state nonradiative decay pathways will facilitate the strategic and targeted development of fluorophores with desired emission properties as versatile chemosensors for broad applications. Full article

(This article belongs to the Special Issue Selected Papers from Optical Materials: Synthesis and Biological Applications Symposium (XXXVIII Biennial Meeting RSEQ))

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13 pages, 2061 KiB

Open AccessEditor’s ChoiceArticle

E-Nose Quality Evaluation of Extra Virgin Olive Oil Stored in Different Containers

by Elísabet Martín-Tornero, Juan Diego Barea-Ramos, Jesús Lozano, Isabel Durán-Merás and Daniel Martín-Vertedor

Chemosensors 2023, 11(2), 85; https://doi.org/10.3390/chemosensors11020085 - 21 Jan 2023

Cited by 7 | Viewed by 2514

Abstract

The degradation process of virgin olive oil (VOO) is related to storage time and the type of storage container used. The aim of this work is to explore the evolution of the VOO quality stored in different container types over a defined storage [...] Read more.

The degradation process of virgin olive oil (VOO) is related to storage time and the type of storage container used. The aim of this work is to explore the evolution of the VOO quality stored in different container types over a defined storage period in order to predict the organoleptic characteristics using a non-destructive technique such as the electronic-nose (E-nose). The “Picual” variety VOO was stored in different containers over a period of 21 months and monitored using sensory analysis, volatile compounds, and an E-nose. The panelists showed that oil stored in dark glass bottles and in green polyethylene bottles began to show defects after 12 and 15 weeks, respectively. However, oil stored in tin containers retained its quality throughout the 21 months studied. A total of 31 volatile compounds were identified, and the evolution of the volatile profile in the different containers during the storage period was studied. The E-nose data were able to classify oil quality by container using principal component analysis (PCA). Furthermore, the E-nose data combined with partial least squares (PLS) regression enabled the building of a predictive model to quantify sensory defect values (

R_{C V}^{2}

= 0.92;

R_{C V}^{2}

= 0.86), evidencing that this technique would be an appropriate screening tool to support a sensory panel. Full article

(This article belongs to the Special Issue GC, MS and GC-MS Analytical Methods: Opportunities and Challenges)

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12 pages, 2760 KiB

Open AccessEditor’s ChoiceArticle

Fe₃O₄-Nanoparticle-Modified Sensor for the Detection of Dopamine, Uric Acid and Ascorbic Acid

by Eduardo Gaya, Nieves Menendez, Eva Mazario and Pilar Herrasti

Chemosensors 2023, 11(2), 79; https://doi.org/10.3390/chemosensors11020079 - 20 Jan 2023

Cited by 18 | Viewed by 2563

Abstract

A simple electrochemical sensor based on electrochemically synthesized Fe₃O₄ nanoparticles was constructed by an ink with the nanoparticles, isopropanol, NAFION and carbon Vulcan to detect dopamine, uric acid and ascorbic acid. The electrocatalytic activity of the nanoparticles for the oxidation [...] Read more.

A simple electrochemical sensor based on electrochemically synthesized Fe₃O₄ nanoparticles was constructed by an ink with the nanoparticles, isopropanol, NAFION and carbon Vulcan to detect dopamine, uric acid and ascorbic acid. The electrocatalytic activity of the nanoparticles for the oxidation of the analyte molecules was examined by means of cyclic voltammetry and square wave voltammetry. The parameters controlling the performance of the sensor were optimized, such as the amount of Fe₃O₄ nanoparticles (1, 2, 3, 5, 8, 10 mg), amount of binder (5, 10, 15 µL) and carbon Vulcan in the ink (4, 6, 8 mg). The temperature was maintained at 25 °C and the pH was 7.5 with buffer phosphate. The optimal sensor conditions were 8 mg magnetite, 4 mg carbon Vulcan and 5 µL of NAFION@ 117. The calibration curves for the three analytes were determined separately, obtaining linear ranges of 10–100, 20–160 and 1050–2300 µM and limits of detection of 4.5, 14 and 95 µM for dopamine, uric acid and ascorbic acid, respectively. This electrochemical sensor has also shown significant sensitivity and selectivity without interference from the three analyte molecules presented simultaneously in solution. This sensor was applied for the detection of these molecules in real samples. Full article

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

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14 pages, 3263 KiB

Open AccessEditor’s ChoiceArticle

Self-Powered Wearable Breath-Monitoring Sensor Enabled by Electromagnetic Harvesting Based on Nano-Structured Electrochemically Active Aluminum

by Marko V. Bošković, Miloš Frantlović, Evgenija Milinković, Predrag D. Poljak, Dana Vasiljević Radović, Jelena N. Stevanović and Milija Sarajlić

Chemosensors 2023, 11(1), 51; https://doi.org/10.3390/chemosensors11010051 - 7 Jan 2023

Cited by 7 | Viewed by 2808

Abstract

Self-powered sensors are gaining a lot of attention in recent years due to their possible application in the Internet of Things, medical implants and wireless and wearable devices. Human breath detection has applications in diagnostics, medical therapy and metabolism monitoring. One possible approach [...] Read more.

Self-powered sensors are gaining a lot of attention in recent years due to their possible application in the Internet of Things, medical implants and wireless and wearable devices. Human breath detection has applications in diagnostics, medical therapy and metabolism monitoring. One possible approach for breath monitoring is detecting the humidity in exhaled air. Here, we present an extremely sensitive, self-powered sensor for breath humidity monitoring. As a power source, the sensor uses electromagnetic energy harvested from the environment. Even electromagnetic energy harvested from the human body is enough for the operation of this sensor. The signal obtained using the human body as a source was up to 100 mV with an estimated power of 1 nW. The relatively low amount of energy that could be harvested in this way was producing a signal that was modulated by an interdigitated capacitor made out of electrochemically activated aluminum. The signal obtained in this way was rectified by a set of Schottky diodes and measured by a voltmeter. The sensor was capable of following a variety of different respiration patterns during normal breathing, exercise and rest, at the same time powered only by electromagnetic energy harvested from the human body. Everything happened in the normal environment used for everyday work and life, without any additional sources, and at a safe level of electromagnetic radiation. Full article

(This article belongs to the Special Issue Nanomaterials in Chemosensors and Biosensors: Development and Application)

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24 pages, 4034 KiB

Open AccessEditor’s ChoiceReview

Recent Advances in Molecularly Imprinted Polymers for Glucose Monitoring: From Fundamental Research to Commercial Application

by Manlio Caldara, Julia Kulpa, Joseph W. Lowdon, Thomas J. Cleij, Hanne Diliën, Kasper Eersels and Bart van Grinsven

Chemosensors 2023, 11(1), 32; https://doi.org/10.3390/chemosensors11010032 - 1 Jan 2023

Cited by 15 | Viewed by 5670

Abstract

Molecularly imprinted polymers (MIPs) have gained growing interest among researchers worldwide, due to their key features that make these materials interesting candidates for implementation as receptors into sensor applications. In fact, MIP-based glucose sensors could overcome the stability issues associated with the enzymes [...] Read more.

Molecularly imprinted polymers (MIPs) have gained growing interest among researchers worldwide, due to their key features that make these materials interesting candidates for implementation as receptors into sensor applications. In fact, MIP-based glucose sensors could overcome the stability issues associated with the enzymes present in commercial glucose devices. Various reports describe the successful development of glucose MIPs and their coupling to a wide variety of transducers for creating sensors that are able to detect glucose in various matrices. In this review, we have summarized and critically evaluated the different production methods of glucose MIPs and the different transducer technologies used in MIP-based glucose sensors, and analyzed these from a commercial point of view. In this way, this review sets out to highlight the most promising approaches in MIP-based sensing in terms of both manufacturing methods and readout technologies employed. In doing so, we aim at delineating potential future approaches and identifying potential obstacles that the MIP-sensing field may encounter in an attempt to penetrate the commercial, analytical market. Full article

(This article belongs to the Special Issue Advances in the Manufacture of Sensors Based on Molecularly Imprinted Polymers)

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17 pages, 7400 KiB

Open AccessEditor’s ChoiceArticle

Au-Decorated Polyaniline-ZnO Electrospun Composite Nanofiber Gas Sensors with Enhanced Response to NO₂ Gas

by Maryam Bonyani, Seyed Mojtaba Zebarjad, Kamal Janghorban, Jin-Young Kim, Hyoun Woo Kim and Sang Sub Kim

Chemosensors 2022, 10(10), 388; https://doi.org/10.3390/chemosensors10100388 - 24 Sep 2022

Cited by 16 | Viewed by 2741

Abstract

Ternary systems are less studied for sensing applications due to complex synthesis procedures. However, they have more sources of resistance modulation, leading to an enhanced gas response. In this study, a ternary system, namely Au-decorated ZnO-polyaniline (PANI) composite nanofibers with different amounts of [...] Read more.

Ternary systems are less studied for sensing applications due to complex synthesis procedures. However, they have more sources of resistance modulation, leading to an enhanced gas response. In this study, a ternary system, namely Au-decorated ZnO-polyaniline (PANI) composite nanofibers with different amounts of PANI (10, 25, and 50 wt.%) were synthesized for NO₂ gas sensing studies. First, ZnO nanofibers were synthesized by electrospinning, and then an Au layer (9 nm) was coated on the ZnO nanofibers. Finally, PANI was coated onto the prepared Au-decorated ZnO nanofibers. NO₂ gas sensing investigations indicated that the sensor with 25 wt.% PANI had the best response to NO₂ gas at 300 °C. In addition, the optimized sensor exhibited high selectivity to NO₂ gas. The improved performance of the optimal gas sensor was attributed to the role of Au, the formation of ZnO-PANI heterojunctions, and the optimal amount of PANI. The promising effect of this ternary system for NO₂ sensing was demonstrated, and it can be extended to other similar systems. Full article

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

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21 pages, 6013 KiB

Open AccessEditor’s ChoiceArticle

Development of a Novel Electrochemical Biosensor Based on Organized Mesoporous Carbon and Laccase for the Detection of Serotonin in Food Supplements

by Dorin Dăscălescu and Constantin Apetrei

Chemosensors 2022, 10(9), 365; https://doi.org/10.3390/chemosensors10090365 - 11 Sep 2022

Cited by 11 | Viewed by 2779

Abstract

Serotonin is a biogenic amine that has multiple roles in the human body and is mainly known as the happiness hormone. A new laccase (Lac)-based biosensor has been developed for the qualitative and quantitative determination of serotonin in three dietary supplements from three [...] Read more.

Serotonin is a biogenic amine that has multiple roles in the human body and is mainly known as the happiness hormone. A new laccase (Lac)-based biosensor has been developed for the qualitative and quantitative determination of serotonin in three dietary supplements from three different manufacturers. The enzyme was immobilized on an organized mesoporous carbon-modified carbon screen-printed electrode (OMC-SPE) by the drop-and-dry method, the active surface being pretreated with glutaraldehyde. With the new biosensor, serotonin was selectively detected from different solutions. Square-wave voltammetry was the technique used for the quantitative determination of serotonin, obtaining a detection limit value of 316 nM and a quantification limit value of 948 nM in the linearity range of 0.1–1.2 µM. The pH for the determinations was 5.2; at this value, the biocatalytic activity of the laccase was optimal. At the same time, the electrochemical performance of the OMC-SPE/Lac biosensor was compared with that of the unmodified sensor, a performance that highlighted the superiority of the biosensor and the very important role of the enzyme in electrodetection. The results obtained from the quantitative determination of serotonin by square-wave voltammetry were compared with those from the FTIR method, revealing a very good correlation between the results obtained by the two quantitative determination methods. Full article

(This article belongs to the Special Issue Voltammperometric Sensors)

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22 pages, 2092 KiB

Open AccessEditor’s ChoiceReview

Electrochemical Sensors and Their Applications: A Review

by Jaya Baranwal, Brajesh Barse, Gianluca Gatto, Gabriela Broncova and Amit Kumar

Chemosensors 2022, 10(9), 363; https://doi.org/10.3390/chemosensors10090363 - 9 Sep 2022

Cited by 292 | Viewed by 57369

Abstract

The world of sensors is diverse and is advancing at a rapid pace due to the fact of its high demand and constant technological improvements. Electrochemical sensors provide a low-cost and convenient solution for the detection of variable analytes and are widely utilized [...] Read more.

The world of sensors is diverse and is advancing at a rapid pace due to the fact of its high demand and constant technological improvements. Electrochemical sensors provide a low-cost and convenient solution for the detection of variable analytes and are widely utilized in agriculture, food, and oil industries as well as in environmental and biomedical applications. The popularity of electrochemical sensing stems from two main advantages: the variability of the reporting signals, such as the voltage, current, overall power output, or electrochemical impedance, and the low theoretical detection limits that originate from the differences in the Faradaic and nonFaradaic currents. This review article attempts to cover the latest advances and applications of electrochemical sensors in different industries. The role of nanomaterials in electrochemical sensor research and advancements is also examined. We believe the information presented here will encourage further efforts on the understanding and progress of electrochemical sensors. Full article

(This article belongs to the Special Issue Electrochemical Detection: Analytical and Biological Challenges)

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12 pages, 2513 KiB

Open AccessEditor’s ChoiceArticle

Polyethylenimine-Based Electrochemical Sensor for the Determination of Caffeic Acid in Aromatic Herbs

by Felipe Zamarchi, Tânia Regina Silva, João Paulo Winiarski, Edson Roberto Santana and Iolanda Cruz Vieira

Chemosensors 2022, 10(9), 357; https://doi.org/10.3390/chemosensors10090357 - 2 Sep 2022

Cited by 26 | Viewed by 3039

Abstract

An electrochemical sensor based on carbon paste modified with polyethyleneimine was developed and employed for the determination of caffeic acid in aromatic herbs. The sensor was prepared by mixing polyethylenimine (1.5% v/v), graphite powder, and mineral oil. The polyethylenimine-based electrode [...] Read more.

An electrochemical sensor based on carbon paste modified with polyethyleneimine was developed and employed for the determination of caffeic acid in aromatic herbs. The sensor was prepared by mixing polyethylenimine (1.5% v/v), graphite powder, and mineral oil. The polyethylenimine-based electrode showed an enhancement of charge transfer at the electrode–solution interface and a higher current intensity for the electrochemical reaction of caffeic acid, in comparison to the unmodified electrode. The calibration plot of caffeic acid constructed in 0.1 mol L⁻¹ acetate buffer (pH 5.0) by square wave voltammetry was linear in the range of 1.25 to 19.9 μmol L⁻¹ with a limit of detection of 0.13 μmol L⁻¹, respectively. Finally, the proposed sensor was employed to monitor the caffeic acid with accuracy in dried Thymus vulgaris and Salvia officinalis samples, with recovery results from 93 to 105%. Full article

(This article belongs to the Special Issue Voltammperometric Sensors)

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34 pages, 4970 KiB

Open AccessEditor’s ChoiceReview

Cellulose-Based Functional Materials for Sensing

by Valeria Gabrielli and Marco Frasconi

Chemosensors 2022, 10(9), 352; https://doi.org/10.3390/chemosensors10090352 - 26 Aug 2022

Cited by 23 | Viewed by 6698

Abstract

The growing bioeconomic demand for lightweight materials with combined sustainability, large-scale production, ease in functionalization and competitive mechanical properties has seen the revival of cellulose as a scaffold for several applications. In particular, due to its multifunctional features, cellulose has found application in [...] Read more.

The growing bioeconomic demand for lightweight materials with combined sustainability, large-scale production, ease in functionalization and competitive mechanical properties has seen the revival of cellulose as a scaffold for several applications. In particular, due to its multifunctional features, cellulose has found application in sensor and biosensor fabrication. Nonetheless, the great variety of cellulose properties and formulations makes the choice of the best suited cellulose-based material for a specific sensing strategy a difficult task. This review offers a critical discussion and guide for the reader towards the understanding of which of the multiple cellulose derivatives and properties can be exploited for the optimal performance of the desired sensing device. We introduce the unique molecular structure, nanoarchitecture and main properties of cellulose and its derivatives. The different functionalization approaches for anchoring receptors on cellulose derivatives and the processing methodologies for fabricating cellulose-based sensors are explored. As far as the use and performance of cellulose-based functional materials in sensors is concerned, we discuss the recent advances of optical and electrochemical sensors and biosensors for biomedical and environmental monitoring. Full article

(This article belongs to the Special Issue 10th Anniversary of Chemosensors—Section 'Materials for Chemical Sensing')

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41 pages, 2036 KiB

Open AccessEditor’s ChoiceReview

Liquid Chromatography on the Different Methods for the Determination of Lipophilicity: An Essential Analytical Tool in Medicinal Chemistry

by José X. Soares, Álvaro Santos, Carla Fernandes and Madalena M. M. Pinto

Chemosensors 2022, 10(8), 340; https://doi.org/10.3390/chemosensors10080340 - 18 Aug 2022

Cited by 29 | Viewed by 8614

Abstract

Lipophilicity is one of many parameters involved in the biological activity of drugs, as it affects their pharmacokinetic and pharmacodynamic behavior. Generally, lipophilicity is assessed by the partition coefficient of a compound between a nonpolar phase (n-octanol) and an aqueous phase [...] Read more.

Lipophilicity is one of many parameters involved in the biological activity of drugs, as it affects their pharmacokinetic and pharmacodynamic behavior. Generally, lipophilicity is assessed by the partition coefficient of a compound between a nonpolar phase (n-octanol) and an aqueous phase (water), expressed as P (partition coefficient) or as its decimal logarithm (Log P). The gold standard method for the experimental determination of Log P is the shake-flask method. In this context, chromatographic methods enable the direct and simple quantification of the partitioned compound between the two phases. This review discusses the use of liquid chromatography (LC) for direct and indirect determination of lipophilicity. Beyond the classical isotropic log P determination, methods for assessing anisotropic lipophilicity are also reviewed. Several examples are discussed that highlight the versatility of LC technique and current trends. The last section of this review focuses on a case study describing an experience of our group and emphasizing the dual role of LC in determining Log P. Full article

(This article belongs to the Collection Women Special Issue in Chemosensors and Analytical Chemistry)

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15 pages, 4902 KiB

Open AccessEditor’s ChoiceArticle

Synthesis of ZIF-8 Coating on ZnO Nanorods for Enhanced Gas-Sensing Performance

by Bo Huang, Wen Zeng and Yanqiong Li

Chemosensors 2022, 10(8), 297; https://doi.org/10.3390/chemosensors10080297 - 30 Jul 2022

Cited by 11 | Viewed by 2881

Abstract

Firstly, ZnO nanorods were prepared by a relatively simple method, and then self-sacrificed by a water bath heating method to generate a commonly used porous ZIF-8 and firmly attached to the ZnO surface. The successful synthesis of synthetic composites was demonstrated with various [...] Read more.

Firstly, ZnO nanorods were prepared by a relatively simple method, and then self-sacrificed by a water bath heating method to generate a commonly used porous ZIF-8 and firmly attached to the ZnO surface. The successful synthesis of synthetic composites was demonstrated with various detection methods. The gas-sensing results show that the ZIF-8-coated ZnO with a core-shell structure exhibits better response than the raw ZnO because of the increased specific surface area and active sites. Full article

(This article belongs to the Special Issue Application and Advance of Gas Sensors)

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24 pages, 18053 KiB

Open AccessEditor’s ChoiceReview

A Critical Review on the Use of Molecular Imprinting for Trace Heavy Metal and Micropollutant Detection

by Patrick Marcel Seumo Tchekwagep, Robert D. Crapnell, Craig E. Banks, Kai Betlem, Uwe Rinner, Francesco Canfarotta, Joseph W. Lowdon, Kasper Eersels, Bart van Grinsven, Marloes Peeters and Jake McClements

Chemosensors 2022, 10(8), 296; https://doi.org/10.3390/chemosensors10080296 - 27 Jul 2022

Cited by 16 | Viewed by 4077

Abstract

Molecular recognition has been described as the “ultimate” form of sensing and plays a fundamental role in biological processes. There is a move towards biomimetic recognition elements to overcome inherent problems of natural receptors such as limited stability, high-cost, and variation in response. [...] Read more.

Molecular recognition has been described as the “ultimate” form of sensing and plays a fundamental role in biological processes. There is a move towards biomimetic recognition elements to overcome inherent problems of natural receptors such as limited stability, high-cost, and variation in response. In recent years, several alternatives have emerged which have found their first commercial applications. In this review, we focus on molecularly imprinted polymers (MIPs) since they present an attractive alternative due to recent breakthroughs in polymer science and nanotechnology. For example, innovative solid-phase synthesis methods can produce MIPs with sometimes greater affinities than natural receptors. Although industry and environmental agencies require sensors for continuous monitoring, the regulatory barrier for employing MIP-based sensors is still low for environmental applications. Despite this, there are currently no sensors in this area, which is likely due to low profitability and the need for new legislation to promote the development of MIP-based sensors for pollutant and heavy metal monitoring. The increased demand for point-of-use devices and home testing kits is driving an exponential growth in biosensor production, leading to an expected market value of over GPB 25 billion by 2023. A key requirement of point-of-use devices is portability, since the test must be conducted at “the time and place” to pinpoint sources of contamination in food and/or water samples. Therefore, this review will focus on MIP-based sensors for monitoring pollutants and heavy metals by critically evaluating relevant literature sources from 1993 to 2022. Full article

(This article belongs to the Special Issue Advances in the Manufacture of Sensors Based on Molecularly Imprinted Polymers)

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24 pages, 2300 KiB

Open AccessEditor’s ChoiceReview

Progress in Electrochemical Biosensing of SARS-CoV-2 Virus for COVID-19 Management

by Md. Mahbubur Rahman

Chemosensors 2022, 10(7), 287; https://doi.org/10.3390/chemosensors10070287 - 20 Jul 2022

Cited by 27 | Viewed by 3775

Abstract

Rapid and early diagnosis of lethal coronavirus disease-19 (COVID-19) caused by the severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) is an important issue considering global human health, economy, education, and other activities. The advancement of understanding of the chemistry/biochemistry and the structure of [...] Read more.

Rapid and early diagnosis of lethal coronavirus disease-19 (COVID-19) caused by the severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) is an important issue considering global human health, economy, education, and other activities. The advancement of understanding of the chemistry/biochemistry and the structure of the SARS-CoV-2 virus has led to the development of low-cost, efficient, and reliable methods for COVID-19 diagnosis over “gold standard” real-time reverse transcription-polymerase chain reaction (RT-PCR) due to its several limitations. This led to the development of electrochemical sensors/biosensors for rapid, fast, and low-cost detection of the SARS-CoV-2 virus from the patient’s biological fluids by detecting the components of the virus, including structural proteins (antigens), nucleic acid, and antibodies created after COVID-19 infection. This review comprehensively summarizes the state-of-the-art research progress of electrochemical biosensors for COVID-19 diagnosis. They include the detection of spike protein, nucleocapsid protein, whole virus, nucleic acid, and antibodies. The review also outlines the structure of the SARS-CoV-2 virus, different detection methods, and design strategies of electrochemical SARS-CoV-2 biosensors by highlighting the current challenges and future perspectives. Full article

(This article belongs to the Special Issue The Application of Electrochemical Sensors or Biosensors Based on Nanomaterials)

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16 pages, 3695 KiB

Open AccessEditor’s ChoiceArticle

Development and Optimization of Electrochemical Method for Determination of Vitamin C

by Ivana Škugor Rončević, Danijela Skroza, Ivana Vrca, Ana Marija Kondža and Nives Vladislavić

Chemosensors 2022, 10(7), 283; https://doi.org/10.3390/chemosensors10070283 - 15 Jul 2022

Cited by 16 | Viewed by 3270

Abstract

The focus of this work was to develop a simple electrochemical method for the determination of vitamin C (VitC) by using a specially constructed microelectrode made from pyrolytic graphite sheet (PGS). A procedure for quantifying VitC in a real sample was established. VitC [...] Read more.

The focus of this work was to develop a simple electrochemical method for the determination of vitamin C (VitC) by using a specially constructed microelectrode made from pyrolytic graphite sheet (PGS). A procedure for quantifying VitC in a real sample was established. VitC shows a single quasi-reversible reaction. The method was optimized, and analytical determination was performed by using cyclic voltammetry and square wave voltammetry for electroanalytical purposes. The obtained results show a linear response of the PGS electrode in a wide concentrations range. For the lower concentration range, 0.18–7.04 µg L⁻¹, the sensitivity is 11.7 µAcm⁻²/mgL⁻¹, while for the higher concentration range, 10.6–70.4 µg L⁻¹, the sensitivity is 134 µAcm⁻²/mgL⁻¹, preserving the linearity of 0.998 and 0.999. The second objective was to determine the effect of the addition of five different types of “green” biowaste on plant growth, VitC content, and antioxidant activity in arugula (Eruca sativa L.) using the developed method. After three weeks of cultivation, small differences in growth and large differences in certain nutritional characteristics were observed. The addition of black coffee makes the soil slightly alkaline and causes a significant increase in VitC content and antioxidant activity. Full article

(This article belongs to the Special Issue Chemosensors and Biosensors for Food Quality and Safety)

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47 pages, 3612 KiB

Open AccessEditor’s ChoiceReview

A Review on Potential Electrochemical Point-of-Care Tests Targeting Pandemic Infectious Disease Detection: COVID-19 as a Reference

by Gokul Chandra Biswas, Swapnila Choudhury, Mohammad Mahbub Rabbani and Jagotamoy Das

Chemosensors 2022, 10(7), 269; https://doi.org/10.3390/chemosensors10070269 - 11 Jul 2022

Cited by 30 | Viewed by 5457

Abstract

Fast and accurate point-of-care testing (POCT) of infectious diseases is crucial for diminishing the pandemic miseries. To fight the pandemic coronavirus disease 2019 (COVID-19), numerous interesting electrochemical point-of-care (POC) tests have been evolved to rapidly identify the causal organism SARS-CoV-2 virus, its nucleic [...] Read more.

Fast and accurate point-of-care testing (POCT) of infectious diseases is crucial for diminishing the pandemic miseries. To fight the pandemic coronavirus disease 2019 (COVID-19), numerous interesting electrochemical point-of-care (POC) tests have been evolved to rapidly identify the causal organism SARS-CoV-2 virus, its nucleic acid and antigens, and antibodies of the patients. Many of those electrochemical biosensors are impressive in terms of miniaturization, mass production, ease of use, and speed of test, and they could be recommended for future applications in pandemic-like circumstances. On the other hand, self-diagnosis, sensitivity, specificity, surface chemistry, electrochemical components, device configuration, portability, small analyzers, and other features of the tests can yet be improved. Therefore, this report reviews the developmental trend of electrochemical POC tests (i.e., test platforms and features) reported for the rapid diagnosis of COVID-19 and correlates any significant advancements with relevant references. POCTs incorporating microfluidic/plastic chips, paper devices, nanomaterial-aided platforms, smartphone integration, self-diagnosis, and epidemiological reporting attributes are also surfed to help with future pandemic preparedness. This review especially screens the low-cost and easily affordable setups so that management of pandemic disease becomes faster and easier. Overall, the review is a wide-ranging package for finding appropriate strategies of electrochemical POCT targeting pandemic infectious disease detection. Full article

(This article belongs to the Special Issue The Application of Electrochemical Sensors or Biosensors Based on Nanomaterials)

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13 pages, 1810 KiB

Open AccessEditor’s ChoiceArticle

UV-Excited Fluorescence as a Basis for the In-Situ Identification of Natural Binders in Historical Painting: A Critical Study on Model Samples

by Margherita Longoni, Ester Sara Cacciola and Silvia Bruni

Chemosensors 2022, 10(7), 256; https://doi.org/10.3390/chemosensors10070256 - 1 Jul 2022

Cited by 4 | Viewed by 2997

Abstract

The fluorescence emission by aged organic binders used in painting is a well-known phenomenon. Several literature studies were devoted to its investigation, both on pure binders and on their mixtures with some pigments. Nevertheless, a systematic study about the real possibility of exploiting [...] Read more.

The fluorescence emission by aged organic binders used in painting is a well-known phenomenon. Several literature studies were devoted to its investigation, both on pure binders and on their mixtures with some pigments. Nevertheless, a systematic study about the real possibility of exploiting such a phenomenon for the non-invasive identification of binders in ancient paintings is still lacking. In the present work, a prototype portable fluorimeter was used to analyze a significant number of model painting samples containing different binders (drying oils, egg yolk, milk, animal glue, and gum Arabic) mixed with various pigments having different hues. The model samples were naturally aged in a period ranging from fifteen to one year. The effects on the spectral pattern due to the different binders, the recipes used to prepare them, and the pigments mixed with them were examined. The fluorescence spectra were corrected for the absorption of the emitted radiation due to the pigments. Finally, the corrected spectra were treated by principal component analysis to determine if the possibility of distinguishing at least the most fluorescent and common binders, i.e., drying oils and egg, existed. It was shown that, even if the technique cannot be effectively applied in the case of mixed or superimposed binders, it allows to put forward at least a preliminary hypothesis when pure binders are used. Full article

(This article belongs to the Special Issue Advances in Fluorescence Sensing)

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22 pages, 5042 KiB

Open AccessEditor’s ChoiceReview

Advances in Electrochemical Techniques for the Detection and Analysis of Genetically Modified Organisms: An Analysis Based on Bibliometrics

by Yuhong Zheng, Hassan Karimi-Maleh and Li Fu

Chemosensors 2022, 10(5), 194; https://doi.org/10.3390/chemosensors10050194 - 21 May 2022

Cited by 18 | Viewed by 4208

Abstract

Since the first successful transgenic plants obtained in 1983, dozens of plants have been tested. On the one hand, genetically modified plants solve the problems of agricultural production. However, due to exogenous genes of transgenic plants, such as its seeds or pollen drift, [...] Read more.

Since the first successful transgenic plants obtained in 1983, dozens of plants have been tested. On the one hand, genetically modified plants solve the problems of agricultural production. However, due to exogenous genes of transgenic plants, such as its seeds or pollen drift, diffusion between populations will likely lead to superweeds or affect the original traits. The detection technology of transgenic plants and their products have received considerable attention. Electrochemical sensing technology is a fast, low-cost, and portable analysis technology. This review interprets the application of electrochemical technology in the analysis and detection of transgenic products through bibliometrics. A total of 83 research articles were analyzed, spanning 2001 to 2021. We described the different stages in the development history of the subject and the contributions of countries and institutions to the topic. Although there were more annual publications in some years, there was no explosive growth in any period. The lack of breakthroughs in this technology is a significant factor in the lack of experts from other fields cross-examining the subject. Through keyword co-occurrence analysis, different research directions on this topic were discussed. The use of nanomaterials with excellent electrical conductivity allows for more sensitive detection of GM crops by electrochemical sensors. Furthermore, co-citation analysis was used to interpret the most popular reports on the topic. In the end, we predict the future development of this topic according to the analysis results. Full article

(This article belongs to the Collection Electrochemical Biosensors for Medical Diagnosis)

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13 pages, 5328 KiB

Open AccessEditor’s ChoiceArticle

Digital Detection of Olive Oil Rancidity Levels and Aroma Profiles Using Near-Infrared Spectroscopy, a Low-Cost Electronic Nose and Machine Learning Modelling

by Claudia Gonzalez Viejo and Sigfredo Fuentes

Chemosensors 2022, 10(5), 159; https://doi.org/10.3390/chemosensors10050159 - 26 Apr 2022

Cited by 9 | Viewed by 3806

Abstract

The success of the olive oil industry depends on provenance and quality-trait consistency affecting the consumers' acceptability/preference and purchase intention. Companies rely on laboratories to analyze samples to assess consistency within the production chain, which may be time-consuming, cost-restrictive, and untimely obtaining results, [...] Read more.

The success of the olive oil industry depends on provenance and quality-trait consistency affecting the consumers' acceptability/preference and purchase intention. Companies rely on laboratories to analyze samples to assess consistency within the production chain, which may be time-consuming, cost-restrictive, and untimely obtaining results, making the process more reactive than predictive. This study proposed implementing digital technologies using near-infrared spectroscopy (NIR) and a novel low-cost e-nose to assess the level of rancidity and aromas in commercial extra-virgin olive oil. Four different olive oils were spiked with three rancidity levels (N = 17). These samples were evaluated using gas-chromatography-mass-spectroscopy, NIR, and an e-nose. Four machine learning models were developed to classify olive oil types and rancidity (Model 1: NIR inputs; Model 2: e-nose inputs) and predict the peak area of 16 aromas (Model 3: NIR; Model 4: e-nose inputs). The results showed high accuracies (Models 1–2: 97% and 87%; Models 3–4: R = 0.96 and 0.93). These digital technologies may change companies from a reactive to a more predictive production of food/beverages to secure product quality and acceptability. Full article

(This article belongs to the Special Issue Chemometrics for Multisensor Systems and Artificial Senses)

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17 pages, 1505 KiB

Open AccessEditor’s ChoiceReview

Advances in Nucleic Acid Amplification-Based Microfluidic Devices for Clinical Microbial Detection

by Thi Ngoc Diep Trinh and Nae Yoon Lee

Chemosensors 2022, 10(4), 123; https://doi.org/10.3390/chemosensors10040123 - 25 Mar 2022

Cited by 14 | Viewed by 4662

Abstract

Accurate and timely detection of infectious pathogens is urgently needed for disease treatment and control of possible outbreaks worldwide. Conventional methods for pathogen detection are usually time-consuming and labor-intensive. Novel strategies for the identification of pathogenic nucleic acids are necessary for practical application. [...] Read more.

Accurate and timely detection of infectious pathogens is urgently needed for disease treatment and control of possible outbreaks worldwide. Conventional methods for pathogen detection are usually time-consuming and labor-intensive. Novel strategies for the identification of pathogenic nucleic acids are necessary for practical application. The advent of microfluidic technology and microfluidic devices has offered advanced and miniaturized tools to rapidly screen microorganisms, improving many drawbacks of conventional nucleic acid amplification-based methods. In this review, we summarize advances in the microfluidic approach to detect pathogens based on nucleic acid amplification. We survey microfluidic platforms performing two major types of nucleic acid amplification strategies, namely, polymerase chain reaction (PCR) and isothermal nucleic acid amplification. We also provide an overview of nucleic acid amplification-based platforms including studies and commercialized products for SARS-CoV-2 detection. Technologically, we focus on the design of the microfluidic devices, the selected methods for sample preparation, nucleic acid amplification techniques, and endpoint analysis. We also compare features such as analysis time, sensitivity, and specificity of different platforms. The first section of the review discusses methods used in microfluidic devices for upstream clinical sample preparation. The second section covers the design, operation, and applications of PCR-based microfluidic devices. The third section reviews two common types of isothermal nucleic acid amplification methods (loop-mediated isothermal amplification and recombinase polymerase amplification) performed in microfluidic systems. The fourth section introduces microfluidic applications for nucleic acid amplification-based detection of SARS-CoV-2. Finally, the review concludes with the importance of full integration and quantitative analysis for clinical microbial identification. Full article

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

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19 pages, 2579 KiB

Open AccessEditor’s ChoiceReview

A Review on the Use of Biochar Derived Carbon Quantum Dots Production for Sensing Applications

by Giovanni Lo Bello, Mattia Bartoli, Mauro Giorcelli, Massimo Rovere and Alberto Tagliaferro

Chemosensors 2022, 10(3), 117; https://doi.org/10.3390/chemosensors10030117 - 19 Mar 2022

Cited by 23 | Viewed by 7196

Abstract

Since their discovery, carbon dots have attracted a great deal of interest for their perspective biological applications. Nevertheless, the quenching of carbon dots photoluminescence represents an interesting feature for quantitative analysis in very low concentration of many species. A particular approach for the [...] Read more.

Since their discovery, carbon dots have attracted a great deal of interest for their perspective biological applications. Nevertheless, the quenching of carbon dots photoluminescence represents an interesting feature for quantitative analysis in very low concentration of many species. A particular approach for the production of carbon dots is the use of biochar, a carbonized biomass, as a precursor. In this work, we overview the main achievements accomplished by using biochar-derived carbon dots for detecting and quantifying inorganic and organic species. We also provide background knowledge of the main properties, production and purification routes of carbon dots. Full article

(This article belongs to the Special Issue Biochar Based Sustainable Sensing Platforms)

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16 pages, 9877 KiB

Open AccessEditor’s ChoiceArticle

Rapid On-Site Detection of Illicit Drugs in Smuggled Samples with a Portable Electrochemical Device

by Marc Parrilla, Amorn Slosse, Robin Van Echelpoel, Noelia Felipe Montiel, Amelia R. Langley, Filip Van Durme and Karolien De Wael

Chemosensors 2022, 10(3), 108; https://doi.org/10.3390/chemosensors10030108 - 11 Mar 2022

Cited by 20 | Viewed by 6165

Abstract

The smuggling of illicit drugs urges the development of new tools for rapid on-site identification in cargos. Current methods rely on presumptive color tests and portable spectroscopic techniques. However, these methods sometimes exhibit inaccurate results due to commonly used cutting agents, the colorful [...] Read more.

The smuggling of illicit drugs urges the development of new tools for rapid on-site identification in cargos. Current methods rely on presumptive color tests and portable spectroscopic techniques. However, these methods sometimes exhibit inaccurate results due to commonly used cutting agents, the colorful nature of the sample or because the drugs are smuggled in common goods. Interestingly, electrochemical sensors can deal with these specific problems. Herein, an electrochemical device is presented that uses affordable screen-printed electrodes for the electrochemical profiling of several illicit drugs by square-wave voltammetry (SWV). The identification of the illicit compound is based on the oxidation potential of the analyte. Hence, a library of electrochemical profiles is built upon the analysis of illicit drugs and common cutting agents. This library allows the design of a tailor-made script that enables the identification of each drug through a user-friendly interface (laptop or mobile phone). Importantly, the electrochemical test is compared by analyzing 48 confiscated samples with other portable devices based on Raman and FTIR spectroscopy as well as a laboratory standard method (i.e., gas chromatography–mass spectrometry). Overall, the electrochemical results, obtained through the analysis of different samples from confiscated cargos at an end-user site, present a promising alternative to current methods, offering low-cost and rapid testing in the field. 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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27 pages, 3968 KiB

Open AccessEditor’s ChoiceReview

Inkjet Printing: A Viable Technology for Biosensor Fabrication

by Arif Hussain, Naseem Abbas and Ahsan Ali

Chemosensors 2022, 10(3), 103; https://doi.org/10.3390/chemosensors10030103 - 9 Mar 2022

Cited by 41 | Viewed by 7743

Abstract

Printing technology promises a viable solution for the low-cost, rapid, flexible, and mass fabrication of biosensors. Among the vast number of printing techniques, screen printing and inkjet printing have been widely adopted for the fabrication of biosensors. Screen printing provides ease of operation [...] Read more.

Printing technology promises a viable solution for the low-cost, rapid, flexible, and mass fabrication of biosensors. Among the vast number of printing techniques, screen printing and inkjet printing have been widely adopted for the fabrication of biosensors. Screen printing provides ease of operation and rapid processing; however, it is bound by the effects of viscous inks, high material waste, and the requirement for masks, to name a few. Inkjet printing, on the other hand, is well suited for mass fabrication that takes advantage of computer-aided design software for pattern modifications. Furthermore, being drop-on-demand, it prevents precious material waste and offers high-resolution patterning. To exploit the features of inkjet printing technology, scientists have been keen to use it for the development of biosensors since 1988. A vast number of fully and partially inkjet-printed biosensors have been developed ever since. This study presents a short introduction on the printing technology used for biosensor fabrication in general, and a brief review of the recent reports related to virus, enzymatic, and non-enzymatic biosensor fabrication, via inkjet printing technology in particular. Full article

(This article belongs to the Special Issue Feature Papers on Optical Chemical Sensors and Biosensors)

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26 pages, 2738 KiB

Open AccessEditor’s ChoiceReview

Flexible Sensors Based on Conductive Polymers

by Ileana-Alexandra Pavel, Sophie Lakard and Boris Lakard

Chemosensors 2022, 10(3), 97; https://doi.org/10.3390/chemosensors10030097 - 1 Mar 2022

Cited by 68 | Viewed by 11313

Abstract

Conductive polymers have attracted wide attention since their discovery due to their unique properties such as good electrical conductivity, thermal and chemical stability, and low cost. With different possibilities of preparation and deposition on surfaces, they present unique and tunable structures. Because of [...] Read more.

Conductive polymers have attracted wide attention since their discovery due to their unique properties such as good electrical conductivity, thermal and chemical stability, and low cost. With different possibilities of preparation and deposition on surfaces, they present unique and tunable structures. Because of the ease of incorporating different elements to form composite materials, conductive polymers have been widely used in a plethora of applications. Their inherent mechanical tolerance limit makes them ideal for flexible devices, such as electrodes for batteries, artificial muscles, organic electronics, and sensors. As the demand for the next generation of (wearable) personal and flexible sensing devices is increasing, this review aims to discuss and summarize the recent manufacturing advances made on flexible electrochemical sensors. Full article

(This article belongs to the Special Issue Smart Polymer-Based Chemical and Biological Sensors)

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12 pages, 1674 KiB

Open AccessEditor’s ChoiceArticle

An Electrochemical and Raman Scattering Dual Detection Biosensor for Rapid Screening and Biomolecular Profiling of Cancer Biomarkers

by Shuvashis Dey, Emtiaz Ahmed, Pranjal Satishchandra Somvanshi, Abu Ali Ibn Sina, Alain Wuethrich and Matt Trau

Chemosensors 2022, 10(3), 93; https://doi.org/10.3390/chemosensors10030093 - 28 Feb 2022

Cited by 6 | Viewed by 3502

Abstract

Detecting circulating biomarkers sensitively and quantitatively is paramount for cancer screening, diagnosis, and treatment selection. Particularly, screening of a panel of circulating protein biomarkers followed by mapping of individual biomarkers could assist better diagnosis and understanding of the cancer progression mechanisms. Herein, we [...] Read more.

Detecting circulating biomarkers sensitively and quantitatively is paramount for cancer screening, diagnosis, and treatment selection. Particularly, screening of a panel of circulating protein biomarkers followed by mapping of individual biomarkers could assist better diagnosis and understanding of the cancer progression mechanisms. Herein, we present a miniaturized biosensing platform with dual readout schemes (electrochemical and Surface enhanced Raman scattering (SERS)) for rapid cancer screening and specific biomarker expressional profiling to support cancer management. Our approach utilizes a controlled nanomixing phenomena under alternative current electrohydrodynamic condition to improve the isolation of cancer-associated circulating proteins (i.e., Epidermal growth factor receptor (EGFR), BRAF, Programmed death-ligand 1 (PD-L1)) with antibody functionalized sensor surface for rapid and efficient isolation of the targets and subsequent labelling with SERS nanotags. The method employs Differential Pulse Voltammetry (DPV) for rapidly screening for the presence of the circulating proteins on biosensor surface irrespective of their type. Upon positive DPV detection, SERS is applied for sensitive read-out of individual biomarkers biomarker levels. In a proof-of-concept study, we demonstrate the dual detection biosensor for analysing circulating BRAF, EGFR and PDL-1 proteins and successfully screened both ensemble and individual biomarker expressional levels as low as 10 pg (1 ng/mL). Our findings clearly indicate the potential of the proposed method for cancer biomarker analysis which may drive the translation of this dual sensing concept in clinical settings. Full article

(This article belongs to the Special Issue Quantitative Sensing in the Microspace)

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