Next Issue
Volume 11, April
Previous Issue
Volume 11, February
 
 

Chemosensors, Volume 11, Issue 3 (March 2023) – 51 articles

Cover Story (view full-size image): Neurotransmitters (NTs) such as dopamine, serotonin, and epinephrine have specific roles in the normal functioning of central nervous systems. The monitoring of NT levels is of paramount importance in the management of neurodegenerative diseases, such as Alzheimer’s and Parkinson’s. Recently, significant attention has been devoted to the fabrication of low-cost, sensitive, and reliable electrochemical sensors for NTs. In this paper, the recent developments in electrochemical sensors based on conducting polymers and metal nanoparticles for NT detection are discussed. The preparation strategies of sensing materials by means of classical methods and innovative methods are also reviewed in terms of improved overall analytical performance. Selected examples of dopamine, serotonin, and epinephrine detection in various samples are presented. View this paper
  • Issues are regarded as officially published after their release is announced to the table of contents alert mailing list.
  • You may sign up for e-mail alerts to receive table of contents of newly released issues.
  • PDF is the official format for papers published in both, html and pdf forms. To view the papers in pdf format, click on the "PDF Full-text" link, and use the free Adobe Reader to open them.
Order results
Result details
Section
Select all
Export citation of selected articles as:
22 pages, 3825 KiB  
Review
Molecularly Imprinted Plasmonic Sensors as Nano-Transducers: An Effective Approach for Environmental Monitoring Applications
by Raphael D. Ayivi, Bukola O. Adesanmi, Eric S. McLamore, Jianjun Wei and Sherine O. Obare
Chemosensors 2023, 11(3), 203; https://doi.org/10.3390/chemosensors11030203 - 22 Mar 2023
Cited by 6 | Viewed by 1898
Abstract
Molecularly imprinted plasmonic nanosensors are robust devices capable of selective target interaction, and in some cases reaction catalysis. Recent advances in control of nanoscale structure have opened the door for development of a wide range of chemosensors for environmental monitoring. The soaring rate [...] Read more.
Molecularly imprinted plasmonic nanosensors are robust devices capable of selective target interaction, and in some cases reaction catalysis. Recent advances in control of nanoscale structure have opened the door for development of a wide range of chemosensors for environmental monitoring. The soaring rate of environmental pollution through human activities and its negative impact on the ecosystem demands an urgent interest in developing rapid and efficient techniques that can easily be deployed for in-field assessment and environmental monitoring purposes. Organophosphate pesticides (OPPs) play a significant role for agricultural use; however, they also present environmental threats to human health due to their chemical toxicity. Plasmonic sensors are thus vital analytical detection tools that have been explored for many environmental applications and OPP detection due to their excellent properties such as high sensitivity, selectivity, and rapid recognition capability. Molecularly imprinted polymers (MIPs) have also significantly been recognized as a highly efficient, low-cost, and sensitive synthetic sensing technique that has been adopted for environmental monitoring of a wide array of environmental contaminants, specifically for very small molecule detection. In this review, the general concept of MIPs and their synthesis, a summary of OPPs and environmental pollution, plasmonic sensing with MIPs, surface plasmon resonance (SPR), surface-enhanced Raman spectroscopy (SERS) MIP sensors, and nanomaterial-based sensors for environmental monitoring applications and OPP detection have been elucidated according to the recent literature. In addition, a conclusion and future perspectives section at the end summarizes the scope of molecularly imprinted plasmonic sensors for environmental applications. Full article
(This article belongs to the Special Issue Molecularly Imprinted Plasmonic Sensor)
Show Figures

Figure 1

24 pages, 6570 KiB  
Review
Organic Thin Film Transistor for Effective Biomarker Detection in Early Disease Diagnosis
by Yifan Wang, Si Cheng, Chenfang Sun and Tie Wang
Chemosensors 2023, 11(3), 202; https://doi.org/10.3390/chemosensors11030202 - 21 Mar 2023
Cited by 1 | Viewed by 2452
Abstract
Recently, people are becoming more concerned about their physical health and putting forward higher requirements for an early and painless diagnosis of diseases. Traditional methods, such as surface plasmon resonance (SPR), enzyme-linked immunosorbent assay (ELISA), surface-enhanced raman spectroscopy (SERS), and colorimetric methods have [...] Read more.
Recently, people are becoming more concerned about their physical health and putting forward higher requirements for an early and painless diagnosis of diseases. Traditional methods, such as surface plasmon resonance (SPR), enzyme-linked immunosorbent assay (ELISA), surface-enhanced raman spectroscopy (SERS), and colorimetric methods have been used for the detection of biomarkers with high selectivity and sensitivity; however, these methods still need to be further improved for immediate and rapid diagnosis. Herein, organic thin-film transistors (OTFTs)-based biosensors offer the advantages of good flexibility, low-cost fabrication, reasonable sensitivity, and great biocompatibility for efficient determination of biomarkers in complex samples, including saliva, sweat, urine, and blood, respectively, exhibiting great potential in early disease diagnosis and clinical treatment. Full article
(This article belongs to the Section (Bio)chemical Sensing)
Show Figures

Figure 1

18 pages, 4489 KiB  
Article
Facile Electrochemical Approach Based on Hydrogen-Bonded MOFs-Derived Tungsten Ethoxide/Polypyrrole-Reduced GO Nanocrystal for ppb Level Ammonium Ions Detection
by Sara Maira Mohd Hizam and Mohamed Shuaib Mohamed Saheed
Chemosensors 2023, 11(3), 201; https://doi.org/10.3390/chemosensors11030201 - 21 Mar 2023
Viewed by 1235
Abstract
Ammonium (NH4+) ions are a primary contaminant in the river and along the waterside near an agricultural area, therefore, necessitating sensitive detection of pollutants before irreversibly damaging environment. Herein, a new approach of metal-organic framework-derived tungsten ethoxide/polypyrrole-reduced graphene oxide (MOFs-W(OCH [...] Read more.
Ammonium (NH4+) ions are a primary contaminant in the river and along the waterside near an agricultural area, therefore, necessitating sensitive detection of pollutants before irreversibly damaging environment. Herein, a new approach of metal-organic framework-derived tungsten ethoxide/polypyrrole-reduced graphene oxide (MOFs-W(OCH2CH3)6/Ppy-rGO) electrochemical sensors are introduced. Through a simple hydrothermal process, Ppy-rGO is linked to tungsten ethoxide as an organic linker. This creates the MOFs-W(OCH2CH3)6/Ppy-rGO nanocrystal through hydrogen bonding. The synergistic combination of tungsten ethoxide and Ppy-rGO provides three-fold advantages: stabilization of Ppy-rGO for extended usage, enabling detection of analytes at ambient temperature, and availability of multiple pathways for effective detection of analytes. This is demonstrated through excellent detection of NH4+ ions over a dynamic concentration range of 0.85 to 3.35 µM with a ppb level detection limit of 0.278 µM (9.74 ppb) and a quantitation limit of 0.843 µM (29.54 ppb). The increment in the concentration of NH4+ ions contributes to the increment in proton (H+) concentration. The increment in proton concentration in the solution will increase the bonding activity and thus increase the conductivity. The cyclic voltammetry curves of all concentrations of NH4+ analytes at the operating potential window between −1.5 and 1.5 V exhibit a quasi-rectangular shape, indicating consistent electronic and ionic transport. The distinctive resistance changes of the MOFs-W(OCH2CH3)6/Ppy-rGO to various NH4+ ion concentrations and ultrasensitive detection provide an extraordinary platform for its application in the agriculture industry. Full article
(This article belongs to the Special Issue Chemical and Biosensors Based on Metal-Organic Frames (MOFs))
Show Figures

Figure 1

16 pages, 3891 KiB  
Article
The Application of Combined Visible and Ultraviolet Irradiation to Improve the Functional Characteristics of Gas Sensors Based on ZnO/SnO2 and ZnO/Au Nanorods
by Alexandra P. Ivanishcheva, Victor V. Sysoev, Khabibulla A. Abdullin, Andrey V. Nesterenko, Soslan A. Khubezhov and Victor V. Petrov
Chemosensors 2023, 11(3), 200; https://doi.org/10.3390/chemosensors11030200 - 20 Mar 2023
Cited by 2 | Viewed by 1420
Abstract
Arrays of zinc oxide (ZnO) nanorods were synthesized over quartz substrates by the hydrothermal method. These nanorods were grown in a predominantly vertical orientation with lengths of 500–800 nm and an average cross-sectional size of 40–80 nm. Gold, with average sizes of 9 [...] Read more.
Arrays of zinc oxide (ZnO) nanorods were synthesized over quartz substrates by the hydrothermal method. These nanorods were grown in a predominantly vertical orientation with lengths of 500–800 nm and an average cross-sectional size of 40–80 nm. Gold, with average sizes of 9 ± 1 nm and 4 ± 0.5 nm, and tin nanoclusters, with average sizes of 30 ± 5 nm and 15 ± 3 nm, were formed on top of the ZnO nanorods. Annealing was carried out at 300 °C for 2 h to form ZnO/SnO2 and ZnO/Au nanorods. The resulting nanorod-arrayed films were comprehensively studied using X-ray diffraction (XRD), scanning electron microscopy (SEM), energy-dispersive X-ray spectrometry (EDS) and X-ray photoelectron spectroscopy (XPS). To fabricate resistive sensor elements, the films were supplied with V/Ni contact metallization on top of the nanorods. The gas sensor performance of the prepared films was evaluated at various temperatures in order to select 200 °C as the optimum one which enabled a selective detection of NO2. Adding UV-viz irradiation via a light-emitting diode, λ = 400 nm, allowed us to reduce the working temperature to 50 °C and to advance the detection limit of NO2 to 0.5 ppm. The minimum response time of the samples was 92 s, which is 9 times faster than in studies without exposure to UV-viz radiation. Full article
(This article belongs to the Special Issue Chemical Sensors for Bio-Medical and Environmental Applications)
Show Figures

Graphical abstract

10 pages, 4146 KiB  
Communication
A Broad Spectral Photodetector Using Organic Bisindolo Quinoxaline on ZnO Nanorods
by Ming-Hsien Li, Yao-Hong Huang, Chi-Chih Chuang, Sang-Hao Lin, Yi-Hsuan Huang, Chia-Feng Lin, Yung-Sen Lin, Ming-Yu Kuo and Hsiang Chen
Chemosensors 2023, 11(3), 199; https://doi.org/10.3390/chemosensors11030199 - 20 Mar 2023
Viewed by 963
Abstract
Inorganic/organic hybrids of ZnO nanorods (NRs)/bisindolo quinoxaline (BIQ) were fabricated for broadband photosensing applications. Multiple material characterizations revealed the BIQ was self-assembled in a regular form of rod-like domain and an irregular form of amorphous aggregation that were distributed on the ZnO NRs. [...] Read more.
Inorganic/organic hybrids of ZnO nanorods (NRs)/bisindolo quinoxaline (BIQ) were fabricated for broadband photosensing applications. Multiple material characterizations revealed the BIQ was self-assembled in a regular form of rod-like domain and an irregular form of amorphous aggregation that were distributed on the ZnO NRs. Optical measurements showed that BIQ can absorb visible light with a wavelength up to 630 nm and effectively generate photoelectrons. Moreover, clustering of BIQ can be observed via the 3D optical microscopy. ZnO/BIQ hybrids were promising for future UV and visible light environmental monitoring applications. Full article
Show Figures

Figure 1

18 pages, 3311 KiB  
Article
Electrochemical Behavior and Voltammetric Determination of Two Synthetic Aroyl Amides Opioids
by Andrea Capucciati, Anna Burato, Chiara Bersani, Stefano Protti, Antonella Profumo and Daniele Merli
Chemosensors 2023, 11(3), 198; https://doi.org/10.3390/chemosensors11030198 - 20 Mar 2023
Cited by 5 | Viewed by 1500
Abstract
In the present work, we describe the electrochemical behaviour of two opioids structurally related to aroyl amides of forensic interest, namely U-47700 and AH-7921. The data obtained allowed for the mise-au-point of a voltammetric determination protocol, that relies on differential pulse voltammetry (DPV) [...] Read more.
In the present work, we describe the electrochemical behaviour of two opioids structurally related to aroyl amides of forensic interest, namely U-47700 and AH-7921. The data obtained allowed for the mise-au-point of a voltammetric determination protocol, that relies on differential pulse voltammetry (DPV) at a glassy carbon electrode in ethanol/0.1 M lithium perchlorate/0.10 M 2,6-lutidine. To apply the method to the analysis of real samples (urines), a clean-up and a preconcentration strategy by solid phase extraction (SPE) using the adsorbent Florisil have been developed. LOQ of 0.2 μg·mL−1 in urine samples with an enrichment factor of 20 and linear range from 5 to 150 μg·mL−1 were obtained. Full article
Show Figures

Graphical abstract

27 pages, 16739 KiB  
Review
Micro/Nano Soft Film Sensors for Intelligent Plant Systems: Materials, Fabrications, and Applications
by Qin Jiang, Zhiping Chai, Zisheng Zong, Zhitong Hu, Shuo Zhang and Zhigang Wu
Chemosensors 2023, 11(3), 197; https://doi.org/10.3390/chemosensors11030197 - 19 Mar 2023
Viewed by 1929
Abstract
Being abundant as natural intelligence, plants have attracted huge attention from researchers. Soft film sensors present a novel and promising approach to connect plants with artificial devices, helping us to investigate plants’ intelligence further. Here, recent developments for micro/nano soft film sensors that [...] Read more.
Being abundant as natural intelligence, plants have attracted huge attention from researchers. Soft film sensors present a novel and promising approach to connect plants with artificial devices, helping us to investigate plants’ intelligence further. Here, recent developments for micro/nano soft film sensors that can be used for establishing intelligent plant systems are summarized, including essential materials, fabrications, and application scenarios. Conductive metals, nanomaterials, and polymers are discussed as basic materials for active layers and substrates of soft film sensors. The corresponding fabrication techniques, such as laser machining, printing, coating, and vapor deposition, have also been surveyed and discussed. Moreover, by combining soft film sensors with plants, applications for intelligent plant systems are also investigated, including plant physiology detection and plant-hybrid systems. Finally, the existing challenges and future opportunities are prospected. Full article
(This article belongs to the Special Issue Low-Cost Chemo/Bio-Sensors Based on Nanomaterials)
Show Figures

Figure 1

29 pages, 7976 KiB  
Review
Surface Plasmon Electrochemistry: Tutorial and Review
by Zohreh Hirbodvash and Pierre Berini
Chemosensors 2023, 11(3), 196; https://doi.org/10.3390/chemosensors11030196 - 19 Mar 2023
Cited by 2 | Viewed by 1789
Abstract
Surface plasmon polaritons (SPPs) are optical surface waves propagating along a metal surface. They exhibit attributes such as field enhancement and sub-wavelength localization, which make them attractive for surface sensing, as they are heavily exploited in surface plasmon biosensors. Electrochemistry also occurs on [...] Read more.
Surface plasmon polaritons (SPPs) are optical surface waves propagating along a metal surface. They exhibit attributes such as field enhancement and sub-wavelength localization, which make them attractive for surface sensing, as they are heavily exploited in surface plasmon biosensors. Electrochemistry also occurs on metal surfaces, and electrochemical techniques are also commonly applied in biosensors. As metal surfaces are integral in both, it is natural to combine these techniques into a single platform. Motivations include: (i) realising a multimodal biosensor (electrochemical and optical), (ii) using SPPs to probe the electrochemical double layer or to probe electrochemical activity, thus revealing complementary information on redox reactions, or (iii) using SPPs to pump electrochemical reactions by creating non-equilibrium energetic electrons and holes in a working electrode through the absorption of SPPs thereon. The latter is of interest as it may yield novel redox reaction pathways (i.e., plasmonic electrocatalysis). Full article
(This article belongs to the Special Issue Recent Developments in Electrochemical Sensing)
Show Figures

Figure 1

15 pages, 3085 KiB  
Article
Bioinspired Materials for Sensor and Clinical Applications: Two Case Studies
by Eleonora Alfinito, Mariangela Ciccarese, Giuseppe Maruccio, Anna Grazia Monteduro and Silvia Rizzato
Chemosensors 2023, 11(3), 195; https://doi.org/10.3390/chemosensors11030195 - 16 Mar 2023
Viewed by 1048
Abstract
The growing interest in bio-inspired materials is driven by the need for increasingly targeted and efficient devices that also have a low ecological impact. These devices often use specially developed materials (e.g., polymers, aptamers, monoclonal antibodies) capable of carrying out the process of [...] Read more.
The growing interest in bio-inspired materials is driven by the need for increasingly targeted and efficient devices that also have a low ecological impact. These devices often use specially developed materials (e.g., polymers, aptamers, monoclonal antibodies) capable of carrying out the process of recognizing and capturing a specific target in a similar way to biomaterials of natural origin. In this article, we present two case studies, in which the target is a biomolecule of medical interest, in particular, α-thrombin and cytokine IL-6. In these examples, different biomaterials are compared to establish, with a theoretical-computational procedure known as proteotronics, which of them has the greatest potential for use in a biodevice. Full article
(This article belongs to the Collection Women Special Issue in Chemosensors and Analytical Chemistry)
Show Figures

Figure 1

16 pages, 3127 KiB  
Article
Experimental-Theoretical Approach for the Chemical Detection of Glyphosate and Its Potential Interferents Using a Copper Complex Fluorescent Probe
by Guilherme Martins, Karolyne V. Oliveira, Saddam Weheabby, Ammar Al-Hamry, Olfa Kanoun, Tobias Rüffer, Benedito J. C. Cabral and Leonardo G. Paterno
Chemosensors 2023, 11(3), 194; https://doi.org/10.3390/chemosensors11030194 - 16 Mar 2023
Cited by 1 | Viewed by 1344
Abstract
The present contribution proposes an optical method for the detection of glyphosate (GLY) using a Cu(II) bis-(oxamate) complex ([Cu(opba)]2−) as the fluorescent probe. It wa found that in acetonitrile solution, its fluorescence increases in the presence of GLY and scales linearly [...] Read more.
The present contribution proposes an optical method for the detection of glyphosate (GLY) using a Cu(II) bis-(oxamate) complex ([Cu(opba)]2−) as the fluorescent probe. It wa found that in acetonitrile solution, its fluorescence increases in the presence of GLY and scales linearly (R2 = 0.99) with GLY concentration in the range of 0.7 to 5.5 µM, which is far below that established by different international regulations. The probe is also selective to GLY in the presence of potential interferents, namely aminomethyl phosphonic acid and N-nitrosoglyphosate. Theoretical results obtained by time-dependent density functional theory coupled to a simplified treatment of the liquid environment by using a self-consistent reaction-field revealed that GLY molecules do not coordinate with the central Cu2+ ion of [Cu(opba)]2−; instead, they interact with its peripheral ligand through hydrogen bond formation. Thereby, GLY plays mainly the role of the proton donor. The results also suggest that GLY increases the dielectric constant of the medium when it contributes to the stabilization of the excited state of the [Cu(opba)]2− and enhancement of its fluorescence. Full article
(This article belongs to the Special Issue Applications of Probe Sensing in Medicine)
Show Figures

Figure 1

12 pages, 1647 KiB  
Article
Elemental Analysis of Heated Soil Samples Using Laser-Induced Breakdown Spectroscopy Assisted with High-Voltage Discharges
by Mitzi Amador-Mejía, Hugo Sobral and Arturo Robledo-Martinez
Chemosensors 2023, 11(3), 193; https://doi.org/10.3390/chemosensors11030193 - 15 Mar 2023
Cited by 2 | Viewed by 1248
Abstract
In this study, a high-voltage (HV) oscillatory square pulse was used to re-excite the laser-induced breakdown spectroscopy (LIBS) signal produced by a nanosecond laser on different loamy soil samples at two different temperatures: ambient and 400 °C. The optimal delay was found for [...] Read more.
In this study, a high-voltage (HV) oscillatory square pulse was used to re-excite the laser-induced breakdown spectroscopy (LIBS) signal produced by a nanosecond laser on different loamy soil samples at two different temperatures: ambient and 400 °C. The optimal delay was found for each experimental scheme to maximize the emission signal-to-noise ratio. The detection limits of various contaminants in the soil were studied for different experimental configurations. It was found that the lowest detection limits were achieved by combining HV discharges with LIBS on heated samples, resulting in improvements of up to a factor of 7 compared to LIBS on room temperature samples. Plasma characterization shows that the increased detection sensitivity is due to the rise in plasma temperature and electron density with HV re-excitation, while an increase in removed matter contributes to the emission intensification observed when samples are heated. Full article
(This article belongs to the Section Optical Chemical Sensors)
Show Figures

Figure 1

11 pages, 3265 KiB  
Article
Carbon Dot-Functionalized Solution-Gated Graphene Transistors for Highly Sensitive Detection of Cobalt(II) Ions
by Zhanpeng Ren, Jianying Wang, Chenglong Xue, Minghua Deng, Ziqin Li, Huibin Zhang, Chen Cai, Bing Xu, Xianbao Wang and Jinhua Li
Chemosensors 2023, 11(3), 192; https://doi.org/10.3390/chemosensors11030192 - 15 Mar 2023
Cited by 1 | Viewed by 1120
Abstract
A carbon dot-functionalized solution-gated graphene transistor (CD-SGGT) was designed and prepared via the modification of CDs on the gate of SGGT. The above CDs were hydrothermally synthesized using DL-thioctic acid and triethylenetramine as C, N and S sources. The average size of CDs [...] Read more.
A carbon dot-functionalized solution-gated graphene transistor (CD-SGGT) was designed and prepared via the modification of CDs on the gate of SGGT. The above CDs were hydrothermally synthesized using DL-thioctic acid and triethylenetramine as C, N and S sources. The average size of CDs was ~6.2 nm, and there were many amino and carboxyl groups on the CDs’ surfaces. The CDs was then used as a probe for preparation of CD-SGGT sensor for the cobalt(II) (Co2+) ions detection. The CD-SGGT sensor showed excellent sensitivity and high selectivity. Remarkably, the limit of detection (LOD) reached 10−19 M. The linear detection range was obtained from 10−19 to 10−15 M. Additionally, the CD-SGGT also showed fast response and good stability. Full article
Show Figures

Graphical abstract

13 pages, 5228 KiB  
Article
Detection of Levofloxacin Using a Simple and Green Electrochemically Polymerized Glycine Layered Carbon Paste Electrode
by Kanthappa Bhimaraya, Jamballi G. Manjunatha, Karnayana P. Moulya, Ammar M. Tighezza, Munirah D. Albaqami and Mika Sillanpää
Chemosensors 2023, 11(3), 191; https://doi.org/10.3390/chemosensors11030191 - 13 Mar 2023
Cited by 11 | Viewed by 1568
Abstract
The easy and rapid analytical tool, electrochemically polymerized (EP) glycine (GN) layered carbon paste electrode (LCPE), was used for the analysis of levofloxacin (LN) using cyclic voltammogram (CV) and differential pulse voltammetry (DPV). The surface features and activities of the electrochemical sensors EPGNLCPE [...] Read more.
The easy and rapid analytical tool, electrochemically polymerized (EP) glycine (GN) layered carbon paste electrode (LCPE), was used for the analysis of levofloxacin (LN) using cyclic voltammogram (CV) and differential pulse voltammetry (DPV). The surface features and activities of the electrochemical sensors EPGNLCPE and bare carbon paste electrode (BCPE) were analyzed using electrochemical impedance spectroscopy (EIS), field emission scanning electron microscopy (FE-SEM), CV and DPV methods. The modified sensor (EPGNLCPE)offers a vibrant and sensitive electrochemical LN oxidation peak by controlling overpotential and the electrode material fouling effect unlike BCPE. Under improved experimental conditions, the DPV method was used to analyze LN on EPGNLCPE by varying its concentration in 0.2 M phosphate buffer solution from 30 to 90 µM, resulting in a good linear relationship(between peak current and concentration), lower limit of detection (LOD: 8.436 × 10−7 M) and lower limit of quantification (LOQ: 2.812 × 10−6 M). Finally, real-time application of the sensor was tested by analyzing LN in medicinal samples, and good LN recovery was observed. Full article
(This article belongs to the Special Issue Electrochemical Sensors in Bioanalytical Chemistry)
Show Figures

Figure 1

14 pages, 4271 KiB  
Article
Surface-Enhanced Raman Spectroscopic Analysis of Flavoenzyme Cofactors: Guidance for Flavin-Related Bio- and Chemo- Sensors
by Yawen Liu, Hao Ma, Junqi Zhao, Jihong Wang, Xiaoxia Han and Bing Zhao
Chemosensors 2023, 11(3), 190; https://doi.org/10.3390/chemosensors11030190 - 12 Mar 2023
Viewed by 1416
Abstract
Flavin mononucleotides (FMNs) and flavin adenine nucleotide (FAD) play vital roles in the electron-transfer processes in diverse enzymatic reactions. Owing to the isoalloxazine chromophore, flavins are easily detectable by surface-enhanced Raman spectroscopy (SERS), a surface-sensitive technique. However, the details of the adsorption of [...] Read more.
Flavin mononucleotides (FMNs) and flavin adenine nucleotide (FAD) play vital roles in the electron-transfer processes in diverse enzymatic reactions. Owing to the isoalloxazine chromophore, flavins are easily detectable by surface-enhanced Raman spectroscopy (SERS), a surface-sensitive technique. However, the details of the adsorption of flavins on SERS-active materials have never been investigated. In this study, a comprehensive SERS analysis of flavins containing lumichrome and lumiflavin on silver nanoparticles was conducted. With the aid of density-functional-theory calculations, our results suggested that the flavin molecules were adsorbed on the silver nanoparticles via the N3 site of the isoalloxazine moiety, which had a stronger adsorption ability than the adenine moiety in the FAD. The SERS spectra of the flavins at different pH values also supported this conclusion. This study demonstrated the feasibility of SERS for the structural characterization of flavins, paving the way for the functional exploration of flavin-labeled detection sensors and flavoprotein researches. Full article
(This article belongs to the Special Issue SERS: Analytical and Biological Challenges)
Show Figures

Figure 1

11 pages, 1810 KiB  
Article
A Facile Surface-Imprinting Strategy for Trypsin-Imprinted Polymeric Chemosensors Using Two-Step Spin-Coating
by Je Wook Byeon, Jin Chul Yang, Chae Hwan Cho, Seok Jin Lim, Jong Pil Park and Jinyoung Park
Chemosensors 2023, 11(3), 189; https://doi.org/10.3390/chemosensors11030189 - 11 Mar 2023
Cited by 3 | Viewed by 1484
Abstract
Surface imprinting used for protein recognition in functional cavities is highly effective in imprinting biomacromolecules to avoid template encapsulation during the formation of a molecularly imprinted polymer (MIP) matrix. Herein, we introduce a facile surface-imprinting method based on two-step spin-coating and photopolymerization to [...] Read more.
Surface imprinting used for protein recognition in functional cavities is highly effective in imprinting biomacromolecules to avoid template encapsulation during the formation of a molecularly imprinted polymer (MIP) matrix. Herein, we introduce a facile surface-imprinting method based on two-step spin-coating and photopolymerization to design highly efficient imprinted sites on polymeric films to detect trypsin (TRY). Well-distributed template imprinting is successfully achieved for maximized sensing responses by controlling the composition of functional monomers and crosslinkers in the precursor solution and the concentration of TRY in the imprinting solution. The MIP film exhibits higher sensitivity (−841 ± 65 Hz/(μg/mL)) with a coefficient of determination of 0.970 and a higher imprinting factor of 4.5 in a 0.24 µg/mL TRY solution compared to the nonimprinted polymer (NIP) film. Moreover, the limit of detection and limit of quantification are calculated to be 25.33 and 84.42 ng/mL, respectively. Finally, the selectivity coefficient is within the range of 3.90–6.78 for TRY against other proteins. These sensing properties are superior to those of the corresponding nonimprinted polymer matrix. Thus, the proposed facile surface-imprinting method is highly effective for protein imprinting with high sensitivity and selectivity. Full article
Show Figures

Graphical abstract

19 pages, 2566 KiB  
Article
Development of a Moisture Pretreatment Device for the Accurate Quantitation of Water-Soluble Volatile Organic Compounds in Air
by Sang-Woo Lee, Trieu-Vuong Dinh, Shin-Young Park, In-Young Choi, In-Young Kim, Byeong-Gyu Park, Da-Hyun Baek, Jae-Hyung Park, Ye-Bin Seo and Jo-Chun Kim
Chemosensors 2023, 11(3), 188; https://doi.org/10.3390/chemosensors11030188 - 11 Mar 2023
Viewed by 1412
Abstract
In air pollutant monitoring using sensors, moisture can adversely affect the analytical accuracy of volatile organic compounds (VOCs). Therefore, a new moisture pretreatment device (KPASS–Odor) for analyzing VOCs in the air was developed, based on frost and created by a desublimation process inside [...] Read more.
In air pollutant monitoring using sensors, moisture can adversely affect the analytical accuracy of volatile organic compounds (VOCs). Therefore, a new moisture pretreatment device (KPASS–Odor) for analyzing VOCs in the air was developed, based on frost and created by a desublimation process inside a cold tube. The performance of KPASS–Odor was compared with conventional devices (i.e., a NafionTM dryer and a cooler) through the measurements of low water-soluble VOCs (i.e., benzene, toluene, ethyl benzene, p-xylene, and styrene) and relatively high ones (i.e., methyl-ethyl ketone, methyl isobutyl ketone, butyl acetate, and isobutyl alcohol) using gas chromatography (GC) and sensor methods. Regarding the GC method, the recovery rates for KPASS–Odor and the cooler were >95% and >80%, respectively, at a flow rate of 500 mL/min for all compounds. For the NafionTM dryer, the recovery rates differed between low and high water-soluble compounds, which exhibited the rates ≥88% and ≤86%, respectively. In terms of the sensor method, the VOC recovery rates of KPASS–Odor and the NafionTM dryer were found to be >90% and <50%, respectively. Therefore, KPASS–Odor was determined to be the most suitable moisture pretreatment device for highly soluble VOCs of concern in this study. Full article
(This article belongs to the Section Analytical Methods, Instrumentation and Miniaturization)
Show Figures

Graphical abstract

15 pages, 6922 KiB  
Article
Highly Sensitive p-SmFeO3/p-YFeO3 Planar-Electrode Sensor for Detection of Volatile Organic Compounds
by Huiyang Liu, Denghui Zhu, Tingting Miao, Weikang Liu, Juan Chen, Bin Cheng, Hongwei Qin and Jifan Hu
Chemosensors 2023, 11(3), 187; https://doi.org/10.3390/chemosensors11030187 - 10 Mar 2023
Cited by 2 | Viewed by 1182
Abstract
Nanocomposites of SmFeO3/YFeO3 (1:0, 0.8:0.2, 0.6:0.4, 0.4:0.6, 0.2:0.8, and 0:1) with different molar proportions were prepared by the sol–gel method. The material’s properties were characterized by various test methods, such as scanning-electron microscopy (SEM) and X-ray photoelectron-diffraction spectrometry (XPS). The [...] Read more.
Nanocomposites of SmFeO3/YFeO3 (1:0, 0.8:0.2, 0.6:0.4, 0.4:0.6, 0.2:0.8, and 0:1) with different molar proportions were prepared by the sol–gel method. The material’s properties were characterized by various test methods, such as scanning-electron microscopy (SEM) and X-ray photoelectron-diffraction spectrometry (XPS). The gas-sensing characteristics of the sensor were tested in darkness and under illumination using monochromatic light with various selected wavelengths. The test results show that the SmFeO3/YFeO3 sensor with the molar ratio of 0.4:0.6 had the highest gas response to volatile organic compound (VOC) gases and that the optimum operating temperature was lower (120 °C). The light illumination improved the sensor’s sensitivity to gas. Under the 370-nanometer light illumination, the sensor’s responses to 30 ppm of ethanol, acetone, and methanol gases were 163.59, 134.02, and 111.637, respectively, which were 1.35, 1.28, and 1.59 times higher, respectively, than those without light. The high gas sensitivity of the sensor was mainly due to the adsorption of oxygen on the material’s surface and the formation of a p–p heterojunction. The SmFeO3/YFeO3 sensor, which can respond to different VOC gases, can be used to detect the safety of unknown environments and provide a timely warning of the presence of dangerous gases in working environments. Full article
(This article belongs to the Special Issue Chemical Sensors for Bio-Medical and Environmental Applications)
Show Figures

Figure 1

16 pages, 4154 KiB  
Article
Macrocyclic Compounds Comprising Tris(3-Aminopropyl)Amine Units and Fluorophore Moieties: Synthesis and Spectroscopic Studies in the Presence of Metal Salts
by Daria S. Kuliukhina, Nataliya M. Chernichenko, Alexei D. Averin, Anton S. Abel, Olga A. Maloshitskaya and Irina P. Beletskaya
Chemosensors 2023, 11(3), 186; https://doi.org/10.3390/chemosensors11030186 - 10 Mar 2023
Viewed by 1113
Abstract
The synthesis of a variety of polyazamacrocyclic compounds comprising structural units of tris(3-aminopropyl)amine (TRPN) and oxadiamines, decorated with one or two fluorophore groups (dansyl or quinoline) at different nitrogen atoms, was carried out using Pd(0)-catalyzed amination. The dependence of the yields of the [...] Read more.
The synthesis of a variety of polyazamacrocyclic compounds comprising structural units of tris(3-aminopropyl)amine (TRPN) and oxadiamines, decorated with one or two fluorophore groups (dansyl or quinoline) at different nitrogen atoms, was carried out using Pd(0)-catalyzed amination. The dependence of the yields of the macrocycles on the synthetic path was observed. The spectrophotometric and fluorescent properties of the target compounds were studied, and their coordination with metal cations using UV–vis, fluorescence spectra as well as NMR titration was investigated. The stoichiometry and binding constants of several complexes with Cu(II), Zn(II), Cd(II), Pb(II) and Hg(II) were established. Three of the six studied macrocycles can be judged as prospective detectors of Zn(II) cations due to the substantial enhancement of fluorescence. Full article
(This article belongs to the Special Issue Advances in Fluorescence Sensing)
Show Figures

Graphical abstract

13 pages, 2729 KiB  
Article
Simultaneous Electrochemical Analysis of Uric Acid and Xanthine in Human Saliva and Serum Samples Using a 3D Reduced Graphene Oxide Nanocomposite-Modified Electrode
by Seong-Hyun Han, Ki Won Moon, Yun Jong Lee and Gi-Ja Lee
Chemosensors 2023, 11(3), 185; https://doi.org/10.3390/chemosensors11030185 - 10 Mar 2023
Cited by 2 | Viewed by 1187
Abstract
Accurate and effective diagnosis and individualized management of gout can be potentially achieved by detecting uric acid (UA) and xanthine (XT) simultaneously using an easy-to-use method. Herein, we report simultaneous detection of UA and XT using a 3-dimensional (3D) macroporous gold nanoparticle-incorporated reduced [...] Read more.
Accurate and effective diagnosis and individualized management of gout can be potentially achieved by detecting uric acid (UA) and xanthine (XT) simultaneously using an easy-to-use method. Herein, we report simultaneous detection of UA and XT using a 3-dimensional (3D) macroporous gold nanoparticle-incorporated reduced graphene oxide–carbon nanotube nanocomposite (GNP/rGO-CNT). The GNP/rGO-CNT was simply prepared on a glassy carbon electrode (GCE) by one-step electrochemical deposition/co-reduction. It displayed highly sensitive and selective responses to UA and XT, showing excellent stability and good reproducibility in neutral pH. It was demonstrated that 3D GNP/rGO-CNT on GCE could detect UA and XT in human saliva and blood serum simultaneously. This GNP/rGO-CNT for simultaneous detection of UA and XT in human body fluids can be utilized for monitoring drug adherence for gout treatment, together with gout diagnosis. Full article
Show Figures

Figure 1

18 pages, 5130 KiB  
Article
Detection of Lysosomal Hg2+ Using a pH-Independent Naphthalene Monoimide-Based Fluoroprobe
by Rupam Roy, Tanoy Dutta, Shruti Nema and Apurba Lal Koner
Chemosensors 2023, 11(3), 184; https://doi.org/10.3390/chemosensors11030184 - 10 Mar 2023
Cited by 3 | Viewed by 1813
Abstract
The development of fluorometric detection methods for toxic metal ions in real samples and inside cellular environments using fluorescent dyes has gained tremendous research interest. This work represents the design and synthesis of a 1,8-naphthalimide-based visible light absorbing fluorescence probe His-NMI-Bu showing an [...] Read more.
The development of fluorometric detection methods for toxic metal ions in real samples and inside cellular environments using fluorescent dyes has gained tremendous research interest. This work represents the design and synthesis of a 1,8-naphthalimide-based visible light absorbing fluorescence probe His-NMI-Bu showing an intramolecular charge transfer (ICT) feature. Photophysical properties of the fluoroprobe are investigated in-depth through a combination of steady-state, time-resolved spectroscopic techniques, and DFT calculation. The probe displays outstanding pH tolerance in the pH range of 5–10 as evident from UV–Vis. and fluorescence measurements. The fluoroprobe exhibits chelation with Hg2+-induced fluorescence attenuation via PET in the solution, thus acting as a suitable fluorescence sensor for mercury ions with LOD 0.52 µM. The high sensitivity and selectivity of the probe towards Hg2+ are validated from fluorescence titration with various metal ions. Banking on its intriguing solid-state emissive properties, dye-loaded filter paper-based sensing of Hg2+ is also developed demonstrating the sensitivity in the micromolar range. Finally, His-NMI-Bu fluorophore depicts its selective localization inside the lysosomal compartment of live cells which assists further to monitor the presence of mercury ions inside the lysosome showing similar Hg2+-induced fluorescence depletion. Full article
Show Figures

Graphical abstract

11 pages, 2585 KiB  
Article
Aptamer Sensor Based on Hybrid Chain Reaction and CRISPR-Cas9 System for STX Detection
by Qinguo Zhao, Guizhen Li and Xuemei Li
Chemosensors 2023, 11(3), 183; https://doi.org/10.3390/chemosensors11030183 - 09 Mar 2023
Cited by 1 | Viewed by 1339
Abstract
In recent years, pollution incidents caused by red tide occur frequently, and the red tide biotoxins brought by it make the food safety problem of seafood become a difficult problem to be solved urgently, which has caused great damage to the mariculture industry. [...] Read more.
In recent years, pollution incidents caused by red tide occur frequently, and the red tide biotoxins brought by it make the food safety problem of seafood become a difficult problem to be solved urgently, which has caused great damage to the mariculture industry. Red tide toxin is also known as “shellfish toxin”. Saxitoxin (STX), is one of the strongest paralytic shellfish toxins and is also one of the most toxic marine toxins, which is extremely harmful. Aiming at the problems existing in the current research on the detection of red tide biotoxin in complex water bodies, this research developed an aptamer sensor based on hybrid chain reaction and a CRISPR-Cas9 gene editing system to detect the toxins of the clam and analyzed the feasibility of this method for the detection of the toxins of the clam. The results showed that the linear range of this method is 5.0 fM to 50 pM, and the detection limit is 1.2 fM. Meanwhile, the recovery rate of this sensor for the detection of toxins is 102.4–104.1% when applied in shellfish extract, which shows significant specificity and the reliability of this detection method. Full article
Show Figures

Figure 1

24 pages, 2016 KiB  
Article
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 - 09 Mar 2023
Cited by 4 | Viewed by 1970
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)
Show Figures

Figure 1

14 pages, 36554 KiB  
Article
Graphene Nanogap Interdigitated Asymmetric Electrodes for Photodetection
by Rabiaa Elkarous, Afrah Bardaoui, Jérôme Borme, Nabil Sghaier, Pedro Alpuim, Diogo M. F. Santos and Radhouane Chtourou
Chemosensors 2023, 11(3), 181; https://doi.org/10.3390/chemosensors11030181 - 08 Mar 2023
Cited by 1 | Viewed by 1924
Abstract
This work proposes a high-performance asymmetric gold/graphene/platinum photodetector. The new photodetector, operating without bias, integrates interdigitated 100 nm spaced metallic contacts that induce a built-in potential and a short carrier path, allowing an improvement in the separation and collection of the photocarriers. A [...] Read more.
This work proposes a high-performance asymmetric gold/graphene/platinum photodetector. The new photodetector, operating without bias, integrates interdigitated 100 nm spaced metallic contacts that induce a built-in potential and a short carrier path, allowing an improvement in the separation and collection of the photocarriers. A chemical vapor deposition graphene layer is transferred onto the interdigitated electrodes elaborated using high-resolution electron-beam lithography. Three devices with different side dimensions (100, 1000, and 3000 µm) are fabricated, and their photoresponsivities are evaluated at different wavelengths. The 100 µm device shows the highest photoresponsivity of 358 A/W at a 400 nm illumination. These promising results confirm the proposed design’s ability to increase the photodetector’s active area, improve light absorption, and achieve high separation and collection of photogenerated carriers. This makes it of great interest for optoelectronic applications. Full article
(This article belongs to the Special Issue Carbon Nanomaterials and Related Materials for Sensing Applications)
Show Figures

Graphical abstract

16 pages, 4738 KiB  
Article
Fabrication of Nanoparticle Agglomerate Films by Spark Ablation and Their Application in Surface-Enhanced Raman Spectroscopy
by Petra Pál, Viktória Horváth, Laura Juhász, Zoltán Kóródi, Attila Kohut and Istvan Csarnovics
Chemosensors 2023, 11(3), 180; https://doi.org/10.3390/chemosensors11030180 - 07 Mar 2023
Cited by 2 | Viewed by 1427
Abstract
This paper presents a systematic study of the investigation of nanoparticle (NP) agglomerate films fabricated via depositing spark-generated Au, Ag, and Au/Ag NPs onto quartz microscope coverslips in a low-pressure inertial impactor. The primary focus of the study is to characterize these nanostructures [...] Read more.
This paper presents a systematic study of the investigation of nanoparticle (NP) agglomerate films fabricated via depositing spark-generated Au, Ag, and Au/Ag NPs onto quartz microscope coverslips in a low-pressure inertial impactor. The primary focus of the study is to characterize these nanostructures and to examine their potential application in surface-enhanced Raman spectroscopy (SERS). The characterization of the produced nanostructures was carried out by performing optical absorbance measurements, morphology, and composition analysis, as well as testing the SERS performance of the NP films at three different excitation laser wavelengths in the visible range. The study aims to investigate the relationship between the optical properties, the morphology, and the enhancement of the produced samples at different excitations, and the results are presented and discussed. The study highlights the potential of using spark ablation and inertial impaction-based deposition as a method for producing nanoparticle films for SERS. Full article
(This article belongs to the Special Issue Nanocomposites for SERS Sensing)
Show Figures

Figure 1

24 pages, 1225 KiB  
Review
Nanocomposite Materials based on Metal Nanoparticles for the Electrochemical Sensing of Neurotransmitters
by Sorina-Alexandra Leau, Cecilia Lete and Stelian Lupu
Chemosensors 2023, 11(3), 179; https://doi.org/10.3390/chemosensors11030179 - 07 Mar 2023
Cited by 12 | Viewed by 2308
Abstract
Neurotransmitters (NTs) are known as endogenous chemical messengers with important roles in the normal functioning of central and peripheral nervous systems. Abnormal levels of certain NTs, such as dopamine, serotonin and epinephrine, have been linked with several neurodegenerative diseases (such as Alzheimer’s disease, [...] Read more.
Neurotransmitters (NTs) are known as endogenous chemical messengers with important roles in the normal functioning of central and peripheral nervous systems. Abnormal levels of certain NTs, such as dopamine, serotonin and epinephrine, have been linked with several neurodegenerative diseases (such as Alzheimer’s disease, Parkinson’s disease and Huntington’s disease). To date, various strategies have been employed for the quantitative determination of NTs, and nanocomposite materials based on conducting polymers and metal nanoparticles constitute a cornerstone for the development of electrochemical sensors with low costs, stability, fast response rates and high selectivity and sensitivity. The preparation and analytical applications of nanocomposite materials based on metal nanoparticles in the electrochemical sensing of neurotransmitters are discussed in this paper. Recent developments in the electrochemical sensing of neurotransmitters are also discussed with emphasis on the benefits brought by metal nanoparticles in improving the sensitivity of the analytical measurements. The electrochemical synthesis methods for the in situ generation of metal nanoparticles within conducting polymer layers are reviewed. The analytical applications of the nanocomposite-sensing materials towards the detection of neurotransmitters such as dopamine, epinephrine and serotonin are discussed in terms of detection and quantification limits, linear response range, sensitivity and selectivity. Full article
Show Figures

Figure 1

18 pages, 1708 KiB  
Article
Monitoring Molecular Structure Changes of Cow and Camel Milk Mixtures during Coagulation: A Study Based on TPA and 2DCOS-MIR Spectroscopy
by Oumayma Boukria, El Mestafa El Hadrami, Shakhnoza Sultanova, Randah Miqbil Alqurashi, Yana Cahyana and Abderrahmane Aït-Kaddour
Chemosensors 2023, 11(3), 178; https://doi.org/10.3390/chemosensors11030178 - 06 Mar 2023
Viewed by 1065
Abstract
The aim of the present study is to evaluate the potential of mid-infrared spectroscopy in combination with two-dimensional correlation spectroscopy (2DCOS) and partial least squares discriminant analysis (PLS-DA) to monitor molecular structure evolution of milk mixtures of two species (cow and camel) during [...] Read more.
The aim of the present study is to evaluate the potential of mid-infrared spectroscopy in combination with two-dimensional correlation spectroscopy (2DCOS) and partial least squares discriminant analysis (PLS-DA) to monitor molecular structure evolution of milk mixtures of two species (cow and camel) during enzymatic coagulation. Molecular structure changes and texture characteristics were investigated on five different milk formulations by mixing camel milk (CaM) and cow milk (CM) (i.e., CaM, CaM3:CM1, CaM1:CM1, CaM1:CM3, and CM, (v/v)). Regarding MIR spectroscopy, two spectral regions were considered to monitor milk coagulation, the fatty acid acyl-chain region (3000–2800 cm−1) and the protein region (1700–1500 cm−1). Different formulation dissimilarities were revealed through the synchronous 2DCOS spectra and their respective auto-peaks. Moreover, using the cross-peak symbols of the synchronous and asynchronous spectra helps to establish the sequence of molecular structure modifications during coagulation. Finally, the analysis of the 2DCOS-MIR synchronous and asynchronous maps by PLS-DA gave good discriminant accuracy (88 to 100%) between each formulation. Those results highlighted that different synchronous and asynchronous chemical phenomena occurred during milk coagulation depending on the milk formulation. Texture attributes were influenced by camel milk ratio in mixtures based on the initial composition of milks. Samples containing more than 50% of CM showed significantly higher hardness compared to pure CaM and CaM3:CM; however, CM gel displayed lower springiness contrary to CaM. Textural characteristics of the resulted gels also confirmed that 2DCOS MIR observations are consistent with textural observations of the gels obtained after milk mixtures coagulation. Full article
(This article belongs to the Section Applied Chemical Sensors)
Show Figures

Graphical abstract

12 pages, 2169 KiB  
Article
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 - 06 Mar 2023
Cited by 8 | Viewed by 1459
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 (KSV) 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 Ir1Ir3 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
Show Figures

Graphical abstract

15 pages, 3692 KiB  
Article
Design of a Boron-Doped Diamond Microcell Grafted with HRP for the Sensitive and Selective Detection of Ochratoxin A
by Amani Chrouda, Dhekra Ayed, Manahil Babiker Elamin, Shazalia Mahmoud Ahmed Ali, Laila M. Alhaidari, Francois Bessueille and Nicole Jaffrezic-Renault
Chemosensors 2023, 11(3), 176; https://doi.org/10.3390/chemosensors11030176 - 05 Mar 2023
Cited by 2 | Viewed by 1736
Abstract
Ochratoxin A (OTA) is considered the most toxic member of the ochratoxin group. Herein, a novel label-free electrochemical sensor based on the horseradish peroxidase (HRP) enzyme is developed for OTA detection. The HRP enzyme was covalently immobilized on the working electrode of a [...] Read more.
Ochratoxin A (OTA) is considered the most toxic member of the ochratoxin group. Herein, a novel label-free electrochemical sensor based on the horseradish peroxidase (HRP) enzyme is developed for OTA detection. The HRP enzyme was covalently immobilized on the working electrode of a planar boron-doped diamond (BDD) electrochemical microcell previously covered with diazonium film and grafted with single-walled carbon nanotubes (SWCNTs). Each surface modification step was evaluated by cyclic voltammetry and scanning electron microscopy. Square wave voltammetry was used for the detection of OTA. The linear working range of the biosensors ranged between 10−14 and 0.1 M, with a limit of detection (LOD) of 10 fM, an RSD equal to 5%, and a sensitivity of 0.8 µA per decade. In addition, the sensor showed good selectivity in the presence of OTA analogs; it was validated in samples such as corn, feed, and wheat. The metrological performance of the present sensor makes it a good alternative for OTA detection. Full article
(This article belongs to the Section Electrochemical Devices and Sensors)
Show Figures

Figure 1

13 pages, 3752 KiB  
Article
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 - 04 Mar 2023
Cited by 2 | Viewed by 1629
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 μM 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
Show Figures

Figure 1

12 pages, 1873 KiB  
Article
Novel Nitrate Ion-Selective Microsensor Fabricated by Means of Direct Ink Writing
by Franc Paré, Aida Visús, Gemma Gabriel and Mireia Baeza
Chemosensors 2023, 11(3), 174; https://doi.org/10.3390/chemosensors11030174 - 04 Mar 2023
Cited by 2 | Viewed by 1131
Abstract
In this work, the stability, electrical conductivity, and versatility of graphite-based inks were taken advantage of to fabricate a nitrate potentiometric sensor. One other key property that was exploited for the design of an ion-selective electrode was the hydrophobicity of graphite. This prevented [...] Read more.
In this work, the stability, electrical conductivity, and versatility of graphite-based inks were taken advantage of to fabricate a nitrate potentiometric sensor. One other key property that was exploited for the design of an ion-selective electrode was the hydrophobicity of graphite. This prevented the formation of a water layer between the solid contact and the polymeric selective membrane. Moreover, given the use of printing technologies for electrode fabrication, it was possible to easily miniaturize the sensors and achieve lower fabrication costs. In this article, a printed sensor, composed of a graphite working electrode and a Ag/AgCl reference electrode, is presented and thoroughly characterized. The working electrode was modified with a well-known PVC-ionophore membrane, and the reference electrode was protected with a PVB-NaCl saturated membrane. It showed almost-Nernstian sensitivity of −(55.4 ± 0.7) mV/dec to NO3, stability of up to 25 days of operation, limit of detection of 0.204 ± 0.009 mM, and repeatability of 99.02 % (N = 3). Coupled with its high selectivity compared with other anions, this low-cost, mass-producible sensor is a great alternative for environmental and industrial applications. Full article
(This article belongs to the Special Issue Chemosensors for Ion Detection)
Show Figures

Figure 1

Previous Issue
Next Issue
Back to TopTop