Research

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16 pages, 4682 KiB

Open AccessArticle

Anion-Sensing Properties of Cyclopentaphenylalanine

by Ivan Petters, Matija Modrušan, Nikolina Vidović, Ivo Crnolatac, Nikola Cindro, Ivo Piantanida, Giovanna Speranza, Gordan Horvat and Vladislav Tomišić

Molecules 2022, 27(12), 3918; https://doi.org/10.3390/molecules27123918 - 18 Jun 2022

Viewed by 1690

Abstract

Cyclic pentaphenylalanine was studied as an efficient anion sensor for halides, thiocyanate and oxoanions in acetonitrile and methanol. Stability constants of the corresponding complexes were determined by means of fluorimetric, spectrophotometric, ¹H NMR, and microcalorimetric titrations. A detailed structural overview of receptor–anion [...] Read more.

Cyclic pentaphenylalanine was studied as an efficient anion sensor for halides, thiocyanate and oxoanions in acetonitrile and methanol. Stability constants of the corresponding complexes were determined by means of fluorimetric, spectrophotometric, ¹H NMR, and microcalorimetric titrations. A detailed structural overview of receptor–anion complexes was obtained by classical molecular dynamics (MD) simulations. The results of ¹H NMR and MD studies indicated that the bound anions were coordinated by the amide groups of cyclopeptide, as expected. Circular dichroism (CD) titrations were also carried out in acetonitrile. To the best of our knowledge, this is the first example of the detection of anion binding by cyclopeptide using CD spectroscopy. The CD spectra were calculated from the structures obtained by MD simulations and were qualitatively in agreement with the experimental data. The stoichiometry of almost all complexes was 1:1 (receptor:anion), except for dihydrogen phosphate where the binding of dihydrogen phosphate dimer was observed in acetonitrile. The affinity of the cyclopeptide receptor was correlated with the structure of anion coordination sphere, as well as with the solvation properties of the examined solvents. Full article

(This article belongs to the Special Issue Recent Advances in Molecular Sensors)

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9 pages, 2097 KiB

Open AccessArticle

A Double-Site Chemodosimeter for Selective Fluorescence Detection of a Nerve Agent Mimic

by Xin Guo, Chang-Xiang Liu, Yuan Lu, Ya-Wen Wang and Yu Peng

Molecules 2022, 27(2), 489; https://doi.org/10.3390/molecules27020489 - 13 Jan 2022

Cited by 8 | Viewed by 1541

Abstract

A novel two-site chemodosimeter (SWJT-4) based on fluorescein skeleton to detect diethyl chlorophosphate (DCP) was designed and synthesized. It is a turn-on fluorescent probe for DCP with good selectivity and obvious color change in aqueous solution. Interestingly, the two oxime groups [...] Read more.

A novel two-site chemodosimeter (SWJT-4) based on fluorescein skeleton to detect diethyl chlorophosphate (DCP) was designed and synthesized. It is a turn-on fluorescent probe for DCP with good selectivity and obvious color change in aqueous solution. Interestingly, the two oxime groups of SWJT-4 as dual response sites initiated different reactions with DCP to form a cyano group and an isoxazole ring, respectively. The corresponding mechanism was confirmed by ¹H NMR, MS and DFT calculation. Moreover, SWJT-4 could be used as a fluorescent test paper to detect DCP vapor. Full article

(This article belongs to the Special Issue Recent Advances in Molecular Sensors)

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10 pages, 9253 KiB

Open AccessArticle

Ferrocene-Labelled Electroactive Aptamer-Based Sensors (Aptasensors) for Glycated Haemoglobin

by Xue-Qing Feng, Yi Ju, Wei-Tao Dou, Qing Li, Zhong-Gan Jin, Xiao-Peng He, Tony D. James and Bang-Ce Ye

Molecules 2021, 26(23), 7077; https://doi.org/10.3390/molecules26237077 - 23 Nov 2021

Cited by 3 | Viewed by 2442

Abstract

Glycated haemoglobin (HbA_1c) is a diagnostic biomarker for type 2 diabetes. Traditional analytical methods for haemoglobin (Hb) detection rely on chromatography, which requires significant instrumentation and is labour-intensive; consequently, miniaturized devices that can rapidly sense HbA_1c are urgently required. With [...] Read more.

Glycated haemoglobin (HbA_1c) is a diagnostic biomarker for type 2 diabetes. Traditional analytical methods for haemoglobin (Hb) detection rely on chromatography, which requires significant instrumentation and is labour-intensive; consequently, miniaturized devices that can rapidly sense HbA_1c are urgently required. With this research, we report on an aptamer-based sensor (aptasensor) for the rapid and selective electrochemical detection of HbA_1c. Aptamers that specifically bind HbA_1c and Hb were modified with a sulfhydryl and ferrocene group at the 3′ and 5′-end, respectively. The modified aptamers were coated through sulfhydryl-gold self-assembly onto screen printed electrodes, producing aptasensors with built in electroactivity. When haemoglobin was added to the electrodes, the current intensity of the ferrocene in the sensor system was reduced in a concentration-dependent manner as determined by differential pulse voltammetry. In addition, electrochemical impedance spectroscopy confirmed selective binding of the analytes to the aptamer-coated electrode. This research offers new insight into the development of portable electrochemical sensors for the detection of HbA_1c Full article

(This article belongs to the Special Issue Recent Advances in Molecular Sensors)

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16 pages, 3890 KiB

Open AccessArticle

A 3D Plasmonic Crossed-Wire Nanostructure for Surface-Enhanced Raman Scattering and Plasmon-Enhanced Fluorescence Detection

by Chun-Ta Huang, Fuh-Jyh Jan and Cheng-Chung Chang

Molecules 2021, 26(2), 281; https://doi.org/10.3390/molecules26020281 - 08 Jan 2021

Cited by 12 | Viewed by 2891

Abstract

In this manuscript, silver nanowire 3D random crossed-wire woodpile (3D-RCW) nanostructures were designed and prepared. The 3D-RCW provides rich “antenna” and “hot spot” effects that are responsive for surface-enhanced Raman scattering (SERS) effects and plasmon-enhanced fluorescence (PEF). The optimal construction mode for the [...] Read more.

In this manuscript, silver nanowire 3D random crossed-wire woodpile (3D-RCW) nanostructures were designed and prepared. The 3D-RCW provides rich “antenna” and “hot spot” effects that are responsive for surface-enhanced Raman scattering (SERS) effects and plasmon-enhanced fluorescence (PEF). The optimal construction mode for the 3D-RCW, based on the ratio of silver nanowire and control compound R6G, was explored and established for use in PEF and SERS analyses. We found that the RCW nanochip capable of emission and Raman-enhanced detections uses micro levels of analysis volumes. Consequently, and SERS and PEF of pesticides (thiram, carbaryl, paraquat, fipronil) were successfully measured and characterized, and their detection limits were within 5 μM~0.05 µM in 20 µL. We found that the designed 3D plasmon-enhanced platform cannot only collect the SERS of pesticides, but also enhance the fluorescence of a weak emitter (pesticides) by more than 1000-fold via excitation of the surface plasmon resonance, which can be used to extend the range of a fluorescence biosensor. More importantly, solid-state measurement using a 3D-RCW nanoplatform shows promising potential based on its dual applications in creating large SERS and PEF enhancements. Full article

(This article belongs to the Special Issue Recent Advances in Molecular Sensors)

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Review

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12 pages, 4220 KiB

Open AccessReview

Use of Silicon Nanowire Sensors for Early Cancer Diagnosis

by Yuri D. Ivanov, Tatyana S. Romanova, Kristina A. Malsagova, Tatyana O. Pleshakova and Alexander I. Archakov

Molecules 2021, 26(12), 3734; https://doi.org/10.3390/molecules26123734 - 18 Jun 2021

Cited by 13 | Viewed by 3042

Abstract

The review covers some research conducted in the field of medical and biomedical application of devices based on silicon sensor elements (Si-NW-sensors). The use of Si-NW-sensors is one of the key methods used in a whole range of healthcare fields. Their biomedical use [...] Read more.

The review covers some research conducted in the field of medical and biomedical application of devices based on silicon sensor elements (Si-NW-sensors). The use of Si-NW-sensors is one of the key methods used in a whole range of healthcare fields. Their biomedical use is among the most important ones as they offer opportunities for early diagnosis of oncological pathologies, for monitoring the prescribed therapy and for improving the people’s quality of life. Full article

(This article belongs to the Special Issue Recent Advances in Molecular Sensors)

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25 pages, 3946 KiB

Open AccessReview

Broad Applications of Thiazole Orange in Fluorescent Sensing of Biomolecules and Ions

by Ohad Suss, Leila Motiei and David Margulies

Molecules 2021, 26(9), 2828; https://doi.org/10.3390/molecules26092828 - 10 May 2021

Cited by 27 | Viewed by 5354

Abstract

Fluorescent sensing of biomolecules has served as a revolutionary tool for studying and better understanding various biological systems. Therefore, it has become increasingly important to identify fluorescent building blocks that can be easily converted into sensing probes, which can detect specific targets with [...] Read more.

Fluorescent sensing of biomolecules has served as a revolutionary tool for studying and better understanding various biological systems. Therefore, it has become increasingly important to identify fluorescent building blocks that can be easily converted into sensing probes, which can detect specific targets with increasing sensitivity and accuracy. Over the past 30 years, thiazole orange (TO) has garnered great attention due to its low fluorescence background signal and remarkable ‘turn-on’ fluorescence response, being controlled only by its intramolecular torsional movement. These features have led to the development of numerous molecular probes that apply TO in order to sense a variety of biomolecules and metal ions. Here, we highlight the tremendous progress made in the field of TO-based sensors and demonstrate the different strategies that have enabled TO to evolve into a versatile dye for monitoring a collection of biomolecules. Full article

(This article belongs to the Special Issue Recent Advances in Molecular Sensors)

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53 pages, 17973 KiB

Open AccessReview

Ratiometric Electrochemistry: Improving the Robustness, Reproducibility and Reliability of Biosensors

by Sam A. Spring, Sean Goggins and Christopher G. Frost

Molecules 2021, 26(8), 2130; https://doi.org/10.3390/molecules26082130 - 07 Apr 2021

Cited by 19 | Viewed by 3849

Abstract

Electrochemical biosensors are an increasingly attractive option for the development of a novel analyte detection method, especially when integration within a point-of-use device is the overall objective. In this context, accuracy and sensitivity are not compromised when working with opaque samples as the [...] Read more.

Electrochemical biosensors are an increasingly attractive option for the development of a novel analyte detection method, especially when integration within a point-of-use device is the overall objective. In this context, accuracy and sensitivity are not compromised when working with opaque samples as the electrical readout signal can be directly read by a device without the need for any signal transduction. However, electrochemical detection can be susceptible to substantial signal drift and increased signal error. This is most apparent when analysing complex mixtures and when using small, single-use, screen-printed electrodes. Over recent years, analytical scientists have taken inspiration from self-referencing ratiometric fluorescence methods to counteract these problems and have begun to develop ratiometric electrochemical protocols to improve sensor accuracy and reliability. This review will provide coverage of key developments in ratiometric electrochemical (bio)sensors, highlighting innovative assay design, and the experiments performed that challenge assay robustness and reliability. Full article

(This article belongs to the Special Issue Recent Advances in Molecular Sensors)

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19 pages, 5348 KiB

Open AccessReview

Azulene—A Bright Core for Sensing and Imaging

by Lloyd C. Murfin and Simon E. Lewis

Molecules 2021, 26(2), 353; https://doi.org/10.3390/molecules26020353 - 12 Jan 2021

Cited by 34 | Viewed by 4837

Abstract

Azulene is a hydrocarbon isomer of naphthalene known for its unusual colour and fluorescence properties. Through the harnessing of these properties, the literature has been enriched with a series of chemical sensors and dosimeters with distinct colorimetric and fluorescence responses. This review focuses [...] Read more.

Azulene is a hydrocarbon isomer of naphthalene known for its unusual colour and fluorescence properties. Through the harnessing of these properties, the literature has been enriched with a series of chemical sensors and dosimeters with distinct colorimetric and fluorescence responses. This review focuses specifically on the latter of these phenomena. The review is subdivided into two sections. Section one discusses turn-on fluorescent sensors employing azulene, for which the literature is dominated by examples of the unusual phenomenon of azulene protonation-dependent fluorescence. Section two focuses on fluorescent azulenes that have been used in the context of biological sensing and imaging. To aid the reader, the azulene skeleton is highlighted in blue in each compound. Full article

(This article belongs to the Special Issue Recent Advances in Molecular Sensors)

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