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641 KiB

Open AccessArticle

Near-Infrared Fluorescence Detection of Acetylcholine in Aqueous Solution Using a Complex of Rhodamine 800 and p-Sulfonato-calix[8]arene

by Takashi Jin

Sensors 2010, 10(3), 2438-2449; https://doi.org/10.3390/s100302438 - 23 Mar 2010

Cited by 36 | Viewed by 12449

Abstract

The complexing properties of p-sulfonatocalix[n]arenes (n = 4: S[4], n = 6: S[6], and n = 8: S[8]) for rhodamine 800 (Rh800) and indocyanine green (ICG) were examined to develop a near-infrared (NIR) fluorescence detection method for acetylcholine (ACh). We found that [...] Read more.

The complexing properties of p-sulfonatocalix[n]arenes (n = 4: S[4], n = 6: S[6], and n = 8: S[8]) for rhodamine 800 (Rh800) and indocyanine green (ICG) were examined to develop a near-infrared (NIR) fluorescence detection method for acetylcholine (ACh). We found that Rh800 (as a cation) forms an inclusion complex with S[n], while ICG (as a twitter ion) have no binding ability for S[n]. The binding ability of Rh800 to S[n] decreased in the order of S[8] > S[6] >> S[4]. By the formation of the complex between Rh800 and S[8], fluorescence intensity of the Rh800 was significantly decreased. From the fluorescence titration of Rh800 by S[8], stoichiometry of the Rh800-S[8] complex was determined to be 1:1 with a dissociation constant of 2.2 mM in PBS. The addition of ACh to the aqueous solution of the Rh800-S[8] complex caused a fluorescence increase of Rh800, resulting from a competitive replacement of Rh800 by ACh in the complex. From the fluorescence change by the competitive fluorophore replacement, stoichiometry of the Rh800-ACh complex was found to be 1:1 with a dissociation constant of 1.7 mM. The effects of other neurotransmitters on the fluorescence spectra of the Rh800-S[8] complex were examined for dopamine, GABA, glycine, and L-asparatic acid. Among the neurotransmitters examined, fluorescence response of the Rh800-S[8] complex was highly specific to ACh. Rh800-S[8] complexes can be used as a NIR fluorescent probe for the detection of ACh (5 × 10^-4−10^-3 M) in PBS buffer (pH = 7.2). Full article

(This article belongs to the Special Issue Fluorescent Chemosensors)

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343 KiB

Open AccessArticle

Fluorescent Silicate Materials for the Detection of Paraoxon

by Brandy J. Johnson, Brian J. Melde, Cassandra Thomas, Anthony P. Malanoski, Iwona A. Leska, Paul T. Charles, Damon A. Parrish and Jeffrey R. Deschamps

Sensors 2010, 10(3), 2315-2331; https://doi.org/10.3390/s100302315 - 19 Mar 2010

Cited by 26 | Viewed by 14259

Abstract

Porphyrins are a family of highly conjugated molecules that strongly absorb visible light and fluoresce intensely. These molecules are sensitive to changes in their immediate environment and have been widely described for optical detection applications. Surfactant-templated organosilicate materials have been described for the [...] Read more.

Porphyrins are a family of highly conjugated molecules that strongly absorb visible light and fluoresce intensely. These molecules are sensitive to changes in their immediate environment and have been widely described for optical detection applications. Surfactant-templated organosilicate materials have been described for the semi-selective adsorption of small molecule contaminants. These structures offer high surface areas and large pore volumes within an organized framework. The organic bridging groups in the materials can be altered to provide varied binding characteristics. This effort seeks to utilize the tunable binding selectivity, high surface area, and low materials density of these highly ordered pore networks and to combine them with the unique spectrophotometric properties of porphyrins. In the porphyrin-embedded materials (PEMs), the organosilicate scaffold stabilizes the porphyrin and facilitates optimal orientation of porphyrin and target. The materials can be stored under ambient conditions and offer exceptional shelf-life. Here, we report on the design of PEMs with specificity for organophosphates and compounds of similar structure. Full article

(This article belongs to the Special Issue Fluorescent Chemosensors)

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306 KiB

Open AccessArticle

Reduced Fluoresceinamine as a Fluorescent Sensor for Nitric Oxide

by Abel J. Duarte and Joaquim C.G. Esteves da Silva

Sensors 2010, 10(3), 1661-1669; https://doi.org/10.3390/s100301661 - 02 Mar 2010

Cited by 13 | Viewed by 11527

Abstract

A new fluorescent sensor for nitric oxide (NO) is presented that is based on its reaction with a non fluorescent substance, reduced fluoresceinamine, producing the highly fluorescent fluoresceinamine. Using a portable homemade stabilized light source consisting of 450 nm LED and fiber optics [...] Read more.

A new fluorescent sensor for nitric oxide (NO) is presented that is based on its reaction with a non fluorescent substance, reduced fluoresceinamine, producing the highly fluorescent fluoresceinamine. Using a portable homemade stabilized light source consisting of 450 nm LED and fiber optics to guide the light, the sensor responds linearly within seconds in the NO concentration range between about 10–750 μM with a limit of detection (LOD) of about 1 μM. The system generated precise intensity readings, with a relative standard deviation of less than 1%. The suitability of the sensor was assessed by monitoring the NO generated by either the nitrous acid decomposition reaction or from a NO-releasing compound. Using relatively high incubation times, the sensor also responds quantitatively to hydrogen peroxide and potassium superoxide, however, using transient signal measurements results in no interfering species. Full article

(This article belongs to the Special Issue Fluorescent Chemosensors)

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373 KiB

Open AccessArticle

Whole-Cell Fluorescent Biosensors for Bioavailability and Biodegradation of Polychlorinated Biphenyls

by Xuemei Liu, Kieran J. Germaine, David Ryan and David N. Dowling

Sensors 2010, 10(2), 1377-1398; https://doi.org/10.3390/s100201377 - 21 Feb 2010

Cited by 47 | Viewed by 16153

Abstract

Whole-cell microbial biosensors are one of the newest molecular tools used in environmental monitoring. Such biosensors are constructed through fusing a reporter gene such as lux, gfp or lacZ,to a responsive promoter. There have been many reports of the applications of [...] Read more.

Whole-cell microbial biosensors are one of the newest molecular tools used in environmental monitoring. Such biosensors are constructed through fusing a reporter gene such as lux, gfp or lacZ,to a responsive promoter. There have been many reports of the applications of biosensors, particularly their use in assaying pollutant toxicity and bioavailability. This paper reviews the basic concepts behind the construction of whole-cell microbial biosensors for pollutant monitoring, and describes the applications of two such biosensors for detecting the bioavailability and biodegradation of Polychlorinated Biphenyls (PCBs). Full article

(This article belongs to the Special Issue Fluorescent Chemosensors)

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306 KiB

Open AccessCommunication

A Lanthanide-Based Chemosensor for Bioavailable Fe³⁺ Using a Fluorescent Siderophore: An Assay Displacement Approach

by Karen M. Orcutt, W. Scott Jones, Andrea McDonald, David Schrock and Karl J. Wallace

Sensors 2010, 10(2), 1326-1337; https://doi.org/10.3390/s100201326 - 11 Feb 2010

Cited by 42 | Viewed by 12255

Abstract

The measurement of trace analytes in aqueous systems has become increasingly important for understanding ocean primary productivity. In oceanography, iron (Fe) is a key element in regulating ocean productivity, microplankton assemblages and has been identified as a causative element in the development of [...] Read more.

The measurement of trace analytes in aqueous systems has become increasingly important for understanding ocean primary productivity. In oceanography, iron (Fe) is a key element in regulating ocean productivity, microplankton assemblages and has been identified as a causative element in the development of some harmful algal blooms.The chemosenor developed in this study is based on an indicator displacement approach that utilizes time-resolved fluorescence and fluorescence resonance energy transfer as the sensing mechanism to achieve detection of Fe³⁺ions as low as 5 nM. This novel approach holds promise for the development of photoactive chemosensors for ocean deployment. Full article

(This article belongs to the Special Issue Fluorescent Chemosensors)

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344 KiB

Open AccessArticle

Fluorescence-based Sensing of 2,4,6-Trinitrotoluene (TNT) Using a Multi-channeled Poly(methyl methacrylate) (PMMA) Microimmunosensor

by Paul T. Charles, Andre A. Adams, Peter B. Howell, Scott A. Trammell, Jeffrey R. Deschamps and Anne W. Kusterbeck

Sensors 2010, 10(1), 876-889; https://doi.org/10.3390/s100100876 - 22 Jan 2010

Cited by 23 | Viewed by 13214

Abstract

Fluorescence immunoassays employing monoclonal antibodies directed against the explosive 2,4,6-trinitrotoluene (TNT) were conducted in a multi-channel microimmunosensor. The multi-channel microimmunosensor was prepared in poly (methyl methacrylate) (PMMA) via hot embossing from a brass molding tool. The multi-channeled microfluidic device was sol-gel coated to [...] Read more.

Fluorescence immunoassays employing monoclonal antibodies directed against the explosive 2,4,6-trinitrotoluene (TNT) were conducted in a multi-channel microimmunosensor. The multi-channel microimmunosensor was prepared in poly (methyl methacrylate) (PMMA) via hot embossing from a brass molding tool. The multi-channeled microfluidic device was sol-gel coated to generate a siloxane surface that provided a scaffold for antibody immobilization. AlexaFluor-cadaverine-trinitrobenzene (AlexaFluor-Cad-TNB) was used as the reporter molecule in a displacement immunoassay. The limit of detection was 1-10 ng/mL (ppb) with a linear dynamic range that covered three orders of magnitude. In addition, antibody crossreactivity was investigated using hexahydro-1,3,5-triazine (RDX), HMX, 2,4-dinitrotoluene (DNT), 4-nitrotoluene (4-NT) and 2-amino-4,6-DNT. Full article

(This article belongs to the Special Issue Fluorescent Chemosensors)

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3226 KiB

Open AccessArticle

Synthesis and Characterization of Anti-HER2 Antibody Conjugated CdSe/CdZnS Quantum Dots for Fluorescence Imaging of Breast Cancer Cells

by Dhermendra K. Tiwari, Shin-Ichi Tanaka, Yasushi Inouye, Keiko Yoshizawa, Tomonobu M. Watanabe and Takashi Jin

Sensors 2009, 9(11), 9332-9354; https://doi.org/10.3390/s91109332 - 19 Nov 2009

Cited by 71 | Viewed by 19777

Abstract

The early detection of HER2 (human epidermal growth factor receptor 2) status in breast cancer patients is very important for the effective implementation of anti-HER2 antibody therapy. Recently, HER2 detections using antibody conjugated quantum dots (QDs) have attracted much attention. QDs are a [...] Read more.

The early detection of HER2 (human epidermal growth factor receptor 2) status in breast cancer patients is very important for the effective implementation of anti-HER2 antibody therapy. Recently, HER2 detections using antibody conjugated quantum dots (QDs) have attracted much attention. QDs are a new class of fluorescent materials that have superior properties such as high brightness, high resistance to photo-bleaching, and multi-colored emission by a single-light source excitation. In this study, we synthesized three types of anti-HER2 antibody conjugated QDs (HER2Ab-QDs) using different coupling agents (EDC/sulfo-NHS, iminothiolane/sulfo-SMCC, and sulfo-SMCC). As water-soluble QDs for the conjugation of antibody, we used glutathione coated CdSe/CdZnS QDs (GSH-QDs) with fluorescence quantum yields of 0.23~0.39 in aqueous solution. Dispersibility, hydrodynamic size, and apparent molecular weights of the GSH-QDs and HER2Ab-QDs were characterized by using dynamic light scattering, fluorescence correlation spectroscopy, atomic force microscope, and size-exclusion HPLC. Fluorescence imaging of HER2 overexpressing cells (KPL-4 human breast cancer cell line) was performed by using HER2Ab-QDs as fluorescent probes. We found that the HER2Ab-QD prepared by using SMCC coupling with partially reduced antibody is a most effective probe for the detection of HER2 expression in KPL-4 cells. We have also studied the size dependency of HER2Ab-QDs (with green, orange, and red emission) on the fluorescence image of KPL-4 cells. Full article

(This article belongs to the Special Issue Fluorescent Chemosensors)

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Review

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1408 KiB

Open AccessReview

Fluorescent Chemosensors for Toxic Organophosphorus Pesticides: A Review

by Sherine O. Obare, Chandrima De, Wen Guo, Tajay L. Haywood, Tova A. Samuels, Clara P. Adams, Noah O. Masika, Desmond H. Murray, Ginger A. Anderson, Keith Campbell and Kenneth Fletcher

Sensors 2010, 10(7), 7018-7043; https://doi.org/10.3390/s100707018 - 21 Jul 2010

Cited by 125 | Viewed by 22104

Abstract

Many organophosphorus (OP) based compounds are highly toxic and powerful inhibitors of cholinesterases that generate serious environmental and human health concerns. Organothiophosphates with a thiophosphoryl (P=S) functional group constitute a broad class of these widely used pesticides. They are related to the more [...] Read more.

Many organophosphorus (OP) based compounds are highly toxic and powerful inhibitors of cholinesterases that generate serious environmental and human health concerns. Organothiophosphates with a thiophosphoryl (P=S) functional group constitute a broad class of these widely used pesticides. They are related to the more reactive phosphoryl (P=O) organophosphates, which include very lethal nerve agents and chemical warfare agents, such as, VX, Soman and Sarin. Unfortunately, widespread and frequent commercial use of OP-based compounds in agricultural lands has resulted in their presence as residues in crops, livestock, and poultry products and also led to their migration into aquifers. Thus, the design of new sensors with improved analyte selectivity and sensitivity is of paramount importance in this area. Herein, we review recent advances in the development of fluorescent chemosensors for toxic OP pesticides and related compounds. We also discuss challenges and progress towards the design of future chemosensors with dual modes for signal transduction. Full article

(This article belongs to the Special Issue Fluorescent Chemosensors)

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293 KiB

Open AccessReview

Environmentally Sensitive Fluorescent Sensors Based on Synthetic Peptides

by Laurence Choulier and Karin Enander

Sensors 2010, 10(4), 3126-3144; https://doi.org/10.3390/s100403126 - 31 Mar 2010

Cited by 23 | Viewed by 11591

Abstract

Biosensors allow the direct detection of molecular analytes, by associating a biological receptor with a transducer able to convert the analyte-receptor recognition event into a measurable signal. We review recent work aimed at developing synthetic fluorescent molecular sensors for a variety of analytes, [...] Read more.

Biosensors allow the direct detection of molecular analytes, by associating a biological receptor with a transducer able to convert the analyte-receptor recognition event into a measurable signal. We review recent work aimed at developing synthetic fluorescent molecular sensors for a variety of analytes, based on peptidic receptors labeled with environmentally sensitive fluorophores. Fluorescent indicators based on synthetic peptides are highly interesting alternatives to protein-based sensors, since they can be synthesized chemically, are stable, and can be easily modified in a site-specific manner for fluorophore coupling and for immobilization on solid supports. Full article

(This article belongs to the Special Issue Fluorescent Chemosensors)

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548 KiB

Open AccessReview

Design Strategies of Fluorescent Biosensors Based on Biological Macromolecular Receptors

by Kazuki Tainaka, Reiko Sakaguchi, Hironori Hayashi, Shun Nakano, Fong Fong Liew and Takashi Morii

Sensors 2010, 10(2), 1355-1376; https://doi.org/10.3390/s100201355 - 12 Feb 2010

Cited by 60 | Viewed by 17641

Abstract

Fluorescent biosensors to detect the bona fide events of biologically important molecules in living cells are increasingly demanded in the field of molecular cell biology. Recent advances in the development of fluorescent biosensors have made an outstanding contribution to elucidating not only the [...] Read more.

Fluorescent biosensors to detect the bona fide events of biologically important molecules in living cells are increasingly demanded in the field of molecular cell biology. Recent advances in the development of fluorescent biosensors have made an outstanding contribution to elucidating not only the roles of individual biomolecules, but also the dynamic intracellular relationships between these molecules. However, rational design strategies of fluorescent biosensors are not as mature as they look. An insatiable request for the establishment of a more universal and versatile strategy continues to provide an attractive alternative, so-called modular strategy, which permits facile preparation of biosensors with tailored characteristics by a simple combination of a receptor and a signal transducer. This review describes an overview of the progress in design strategies of fluorescent biosensors, such as auto-fluorescent protein-based biosensors, protein-based biosensors covalently modified with synthetic fluorophores, and signaling aptamers, and highlights the insight into how a given receptor is converted to a fluorescent biosensor. Furthermore, we will demonstrate a significance of the modular strategy for the sensor design. Full article

(This article belongs to the Special Issue Fluorescent Chemosensors)

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371 KiB

Open AccessReview

Use of Biosensors as Alternatives to Current Regulatory Methods for Marine Biotoxins

by Natalia Vilariño, Eva S. Fonfría, M. Carmen Louzao and Luis M. Botana

Sensors 2009, 9(11), 9414-9443; https://doi.org/10.3390/s91109414 - 24 Nov 2009

Cited by 40 | Viewed by 16404

Abstract

Marine toxins are currently monitored by means of a bioassay that requires the use of many mice, which poses a technical and ethical problem in many countries. With the exception of domoic acid, there is a legal requirement for the presence of other [...] Read more.

Marine toxins are currently monitored by means of a bioassay that requires the use of many mice, which poses a technical and ethical problem in many countries. With the exception of domoic acid, there is a legal requirement for the presence of other toxins (yessotoxin, saxitoxin and analogs, okadaic acid and analogs, pectenotoxins and azaspiracids) in seafood to be controlled by bioassay, but other toxins, such as palytoxin, cyclic imines, ciguatera and tetrodotoxin are potentially present in European food and there are no legal requirements or technical approaches available to identify their presence. The need for alternative methods to the bioassay is clearly important, and biosensors have become in recent years a feasible alternative to animal sacrifice. This review will discuss the advantages and disadvantages of using biosensors as alternatives to animal assays for marine toxins, with particular focus on surface plasmon resonance (SPR) technology. Full article

(This article belongs to the Special Issue Fluorescent Chemosensors)

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159 KiB

Open AccessReview

Sensing Mercury for Biomedical and Environmental Monitoring

by Paul D. Selid, Hanying Xu, E. Michael Collins, Marla Striped Face-Collins and Julia Xiaojun Zhao

Sensors 2009, 9(7), 5446-5459; https://doi.org/10.3390/s90705446 - 09 Jul 2009

Cited by 163 | Viewed by 19344

Abstract

Mercury is a very toxic element that is widely spread in the atmosphere, lithosphere, and surface water. Concentrated mercury poses serious problems to human health, as bioaccumulation of mercury within the brain and kidneys ultimately leads to neurological diseases. To control mercury pollution [...] Read more.

Mercury is a very toxic element that is widely spread in the atmosphere, lithosphere, and surface water. Concentrated mercury poses serious problems to human health, as bioaccumulation of mercury within the brain and kidneys ultimately leads to neurological diseases. To control mercury pollution and reduce mercury damage to human health, sensitive determination of mercury is important. This article summarizes some current sensors for the determination of both abiotic and biotic mercury. A wide array of sensors for monitoring mercury is described, including biosensors and chemical sensors, while piezoelectric and microcantilever sensors are also described. Additionally, newly developed nanomaterials offer great potential for fabricating novel mercury sensors. Some of the functional fluorescent nanosensors for the determination of mercury are covered. Afterwards, the in vivo determination of mercury and the characterization of different forms of mercury are discussed. Finally, the future direction for mercury detection is outlined, suggesting that nanomaterials may provide revolutionary tools in biomedical and environmental monitoring of mercury. Full article

(This article belongs to the Special Issue Fluorescent Chemosensors)

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