Sensors

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10 pages, 1357 KiB

Open AccessCommunication

Short Duplex Module Coupled to G-Quadruplexes Increases Fluorescence of Synthetic GFP Chromophore Analogues

by Snizhana O. Zaitseva, Nadezhda S. Baleeva, Timofei S. Zatsepin, Ivan N. Myasnyanko, Anton V. Turaev, Galina E. Pozmogova, Alexei A. Khrulev, Anna M. Varizhuk, Mikhail S. Baranov and Andrey V. Aralov

Sensors 2020, 20(3), 915; https://doi.org/10.3390/s20030915 - 9 Feb 2020

Cited by 1 | Viewed by 4024

Abstract

Aptasensors became popular instruments in bioanalytical chemistry and molecular biology. To increase specificity, perspective signaling elements in aptasensors can be separated into a G-quadruplex (G4) part and a free fluorescent dye that lights up upon binding to the G4 part. However, current systems [...] Read more.

Aptasensors became popular instruments in bioanalytical chemistry and molecular biology. To increase specificity, perspective signaling elements in aptasensors can be separated into a G-quadruplex (G4) part and a free fluorescent dye that lights up upon binding to the G4 part. However, current systems are limited by relatively low enhancement of fluorescence upon dye binding. Here, we added duplex modules to G4 structures, which supposedly cause the formation of a dye-binding cavity between two modules. Screening of multiple synthetic GFP chromophore analogues and variation of the duplex module resulted in the selection of dyes that light up after complex formation with two-module structures and their RNA analogues by up to 20 times compared to parent G4s. We demonstrated that the short duplex part in TBA25 is preferable for fluorescence light up in comparison to parent TBA15 molecule as well as TBA31 and TBA63 stabilized by longer duplexes. Duplex part of TBA25 may be partially unfolded and has reduced rigidity, which might facilitate optimal dye positioning in the joint between G4 and the duplex. We demonstrated dye enhancement after binding to modified TBA, LTR-III, and Tel23a G4 structures and propose that such architecture of short duplex-G4 signaling elements will enforce the development of improved aptasensors. Full article

(This article belongs to the Special Issue Fluorescent Biosensors 2019)

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19 pages, 4150 KiB

Open AccessArticle

Development of Ratiometric Fluorescence Sensors Based on CdSe/ZnS Quantum Dots for the Detection of Hydrogen Peroxide

by Hong Dinh Duong and Jong Il Rhee

Sensors 2019, 19(22), 4977; https://doi.org/10.3390/s19224977 - 15 Nov 2019

Cited by 12 | Viewed by 2742

Abstract

In this study, carboxyl group functionalized-CdSe/ZnS quantum dots (QDs) and aminofluorescein (AF)-encapsulated polymer particles were synthesized and immobilized to a sol–gel mixture of glycidoxypropyl trimethoxysilane (GPTMS) and aminopropyl trimethoxysilane (APTMS) for the fabrication of a hydrogen peroxide-sensing membrane. CdSe/ZnS QDs were used for [...] Read more.

In this study, carboxyl group functionalized-CdSe/ZnS quantum dots (QDs) and aminofluorescein (AF)-encapsulated polymer particles were synthesized and immobilized to a sol–gel mixture of glycidoxypropyl trimethoxysilane (GPTMS) and aminopropyl trimethoxysilane (APTMS) for the fabrication of a hydrogen peroxide-sensing membrane. CdSe/ZnS QDs were used for the redox reaction of hydrogen peroxide (H₂O₂) via a reductive pathway by transferring electrons to the acceptor that led to fluorescence quenching of QDs, while AF was used as a reference dye. Herein, the ratiometric fluorescence intensity of CdSe/ZnS QDs and AF was proportional to the concentration of hydrogen peroxide. The fluorescence membrane (i.e., QD–AF membrane) could detect hydrogen peroxide in linear detection ranges from 0.1 to 1.0 mM with a detection limit (LOD) of 0.016 mM and from 1.0 to 10 mM with an LOD of 0.058 mM. The sensitivity of the QD–AF membrane was increased by immobilizing horseradish peroxidase (HRP) over the surface of the QD–AF membrane (i.e., HRP–QD–AF membrane). The HRP–QD–AF membrane had an LOD of 0.011 mM for 0.1–1 mM H₂O₂ and an LOD of 0.068 mM for 1–10 mM H₂O₂. It showed higher sensitivity than the QD–AF membrane only, although both membranes had good selectivity. The HRP–QD–AF membrane could be applied to determine the concentration of hydrogen peroxide in wastewater, while the QD–AF membrane could be employed for the detection of α-ketobutyrate. Full article

(This article belongs to the Special Issue Fluorescent Biosensors 2019)

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11 pages, 1297 KiB

Open AccessArticle

A New pH-Dependent Macrocyclic Rhodamine B-Based Fluorescent Probe for Copper Detection in White Wine

by Nour Doumani, Elias Bou-Maroun, Jacqueline Maalouly, Maya Tueni, Adrien Dubois, Claire Bernhard, Franck Denat, Philippe Cayot and Nicolas Sok

Sensors 2019, 19(20), 4514; https://doi.org/10.3390/s19204514 - 17 Oct 2019

Cited by 17 | Viewed by 3673

Abstract

For efficiently measuring copper (II) ions in the acidic media of white wine, a new chemosensor based on rhodamine B coupled to a tetraazamacrocyclic ring (13aneN₄CH₂NH₂) was designed and synthesized by a one-pot reaction using ethanol as [...] Read more.

For efficiently measuring copper (II) ions in the acidic media of white wine, a new chemosensor based on rhodamine B coupled to a tetraazamacrocyclic ring (13aneN₄CH₂NH₂) was designed and synthesized by a one-pot reaction using ethanol as a green solvent. The obtained chemosensor was characterized via NMR, UV and fluorescent spectra. It was marked with no color emission under neutral pH conditions, with a pink color emission under acidic conditions, and a magenta color emission under acidic conditions where copper (II) ions were present. The sensitivity towards copper (II) ions was tested and verified over Ca²⁺, Ag⁺, Zn²⁺, Mg²⁺, Co²⁺, Ni²⁺, Fe²⁺, Pb²⁺, Cd²⁺, Fe³⁺, and Mn²⁺, with a detection limit of 4.38

\times

10⁻⁸ M in the fluorescence spectrum. Full article

(This article belongs to the Special Issue Fluorescent Biosensors 2019)

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15 pages, 2858 KiB

Open AccessArticle

Label-Free Fluorescent Aptasensor for Small Targets via Displacement of Groove Bound Curcumin Molecules

by Baraa J. Alyamani, Omar A. Alsager and Mohammed Zourob

Sensors 2019, 19(19), 4181; https://doi.org/10.3390/s19194181 - 26 Sep 2019

Cited by 10 | Viewed by 3495

Abstract

Signal transduction based on fluorescence is one of the most common optical aptasensors for small molecules. Sensors with a number of unique features including high sensitivity, low cost, and simple operation can be constructed easily. However, the label-free fluorescent approach is limited to [...] Read more.

Signal transduction based on fluorescence is one of the most common optical aptasensors for small molecules. Sensors with a number of unique features including high sensitivity, low cost, and simple operation can be constructed easily. However, the label-free fluorescent approach is limited to synthetic dyes that bind strongly to the aptamer sequence and result in a diminished sensor operation with high detection limits. In this study, we report the use of curcumin as a fluorescent probe to signal aptamer/small target binding events. A substantial enhancement in curcumin’s fluorescent emission was observed when bound into the grooves of vitamin D₃ (VTD3) binding aptamer, as an example. However, the introduction of the target molecule causes the aptamer to undergo a conformational change that favors complexing the target molecule over binding the curcumin dye. The sensor was able to detect VTD3 down to 1 fM concentration in buffer solutions and extracted blood samples, operate at a wide dynamic range, and discriminate against potential biological interfering molecules including VTD2. The operation of the curcumin based fluorescent sensor is at least six orders of magnitude more sensitive than a VTD3 sensor constructed with the synthetic dye SYBR Green I. The generality of the reported label-free approach was applied with a previously isolated 75-mer bisphenol-A (BPA) aptamer, confirming that the reported sensing strategy is not confined on a particular aptamer sequence. Our work not only reports a novel sensor format for the detection of small molecules, but also serves fluorescent sensor’s most pressing need being novel fluorophores for multiplex targets detection. Full article

(This article belongs to the Special Issue Fluorescent Biosensors 2019)

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12 pages, 2349 KiB

Open AccessArticle

Red Fluorescent Genetically Encoded Voltage Indicators with Millisecond Responsiveness

by Liubov A. Kost, Violetta O. Ivanova, Pavel M. Balaban, Konstantin A. Lukyanov, Evgeny S. Nikitin and Alexey M. Bogdanov

Sensors 2019, 19(13), 2982; https://doi.org/10.3390/s19132982 - 6 Jul 2019

Cited by 3 | Viewed by 3658

Abstract

Genetically encoded fluorescent indicators typically consist of the sensitive and reporter protein domains connected with the amino acid linkers. The final performance of a particular indicator may depend on the linker length and composition as strong as it depends on the both domains [...] Read more.

Genetically encoded fluorescent indicators typically consist of the sensitive and reporter protein domains connected with the amino acid linkers. The final performance of a particular indicator may depend on the linker length and composition as strong as it depends on the both domains nature. Here we aimed to optimize interdomain linkers in VSD-FR189-188—a recently described red fluorescent protein-based voltage indicator. We have tested 13 shortened linker versions and monitored the dynamic range, response speed and polarity of the corresponding voltage indicator variants. While the new indicators didn’t show a contrast enhancement, some of them carrying very short interdomain linkers responded 25-fold faster than the parental VSD-FR189-188. Also we found the critical linker length at which fluorescence response to voltage shift changes its polarity from negative to positive slope. Our observations thus make an important contribution to the designing principles of the fluorescent protein-derived voltage indicators. Full article

(This article belongs to the Special Issue Fluorescent Biosensors 2019)

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9 pages, 1357 KiB

Open AccessArticle

DNAzyme-Functionalized R-Phycoerythrin as a Cost-Effective and Environment-Friendly Fluorescent Biosensor for Aqueous Pb²⁺ Detection

by Jikui Wu, Yunfei Lu, Ningna Ren, Min Jia, Ruinan Wang and Junling Zhang

Sensors 2019, 19(12), 2732; https://doi.org/10.3390/s19122732 - 18 Jun 2019

Cited by 16 | Viewed by 3819

Abstract

The sensitive detection of Pb²⁺ is of significant importance for food safety, environmental monitoring, and human health care. To this end, a novel fluorescent biosensor, DNAzyme-functionalized R-phycoerythrin (DNAzyme-R-PE), was presented for Pb²⁺ analysis. The biosensor was prepared via the immobilization of [...] Read more.

The sensitive detection of Pb²⁺ is of significant importance for food safety, environmental monitoring, and human health care. To this end, a novel fluorescent biosensor, DNAzyme-functionalized R-phycoerythrin (DNAzyme-R-PE), was presented for Pb²⁺ analysis. The biosensor was prepared via the immobilization of Iowa Black^® FQ-modified DNAzyme–substrate complex onto the surface of SPDP-functionalized R-PE. The biosensor produced a minimal fluorescence signal in the absence of Pb²⁺. However, Pb²⁺ recognition can induce the cleavage of substrate, resulting in a fluorescence restoration of R-PE. The fluorescence changes were used to measure sensitively Pb²⁺ and the limit of detection was 0.16 nM with a linear range from 0.5–75 nM. Furthermore, the proposed biosensor showed excellent selectivity towards Pb²⁺ even in the presence of other metal ions interferences and was demonstrated to successfully determine Pb²⁺ in spiked lake water samples. Full article

(This article belongs to the Special Issue Fluorescent Biosensors 2019)

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7 pages, 1167 KiB

Open AccessCommunication

A Schiff Base Fluorescence Enhancement Probe for Fe(III) and Its Sensing Applications in Cancer Cells

by Na Hee Kim, Junho Lee, Sungnam Park, Junyang Jung and Dokyoung Kim

Sensors 2019, 19(11), 2500; https://doi.org/10.3390/s19112500 - 31 May 2019

Cited by 24 | Viewed by 4511

Abstract

We report a new Schiff base fluorescent probe which senses ferric ion, Fe(III), with a significant fluorescence enhancement response. The probe showed high sensitivity (0.8 ppb), and fast response time (<10 s) of Fe(III) in aqueous media. In addition, the probe showed the [...] Read more.

We report a new Schiff base fluorescent probe which senses ferric ion, Fe(III), with a significant fluorescence enhancement response. The probe showed high sensitivity (0.8 ppb), and fast response time (<10 s) of Fe(III) in aqueous media. In addition, the probe showed the ability to sense Fe(III) in a HeLa cancer cell line, with very low cytotoxicity. As a new bio-imaging probe for Fe(III), it gave bright fluorescent images in confocal laser scanning microscopy (CLSM). Full article

(This article belongs to the Special Issue Fluorescent Biosensors 2019)

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8 pages, 1213 KiB

Open AccessCommunication

Single-Step Detection of the Influenza Virus Hemagglutinin Using Bacterially-Produced Quenchbodies

by Hee-Jin Jeong, Jinhua Dong and Hiroshi Ueda

Sensors 2019, 19(1), 52; https://doi.org/10.3390/s19010052 - 23 Dec 2018

Cited by 21 | Viewed by 4186

Abstract

We have successfully generated a Quenchbody that enables the detection of the influenza virus hemagglutinin (HA), in a simple and convenient manner. By two-site labeling of the bacterially-produced anti-HA Fab with ATTO520, its fluorescence intensity was increased to 4.4-fold, in the presence of [...] Read more.

We have successfully generated a Quenchbody that enables the detection of the influenza virus hemagglutinin (HA), in a simple and convenient manner. By two-site labeling of the bacterially-produced anti-HA Fab with ATTO520, its fluorescence intensity was increased to 4.4-fold, in the presence of a nanomolar concentration of H1N1 HA. Our results indicate the potential use of this Quenchbody, as a sensor for the simple in situ detection of influenza A virus. Full article

(This article belongs to the Special Issue Fluorescent Biosensors 2019)

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