<i>In vivo</i>sodium concentration continuously monitored with fluorescent sensors

Dubach, J. Matthew; Lim, E. C.; Zhang, Ning; Francis, Kevin P.; Clark, Heather A.

doi:10.1039/c0ib00020e

Cited by 41 publications

(35 citation statements)

References 41 publications

(43 reference statements)

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“…Among the limited number of Na + sensors, such as sodium-binding benzofuran isophthalate (22), Sodium Green (23), CoroNa Green/Red (24,25), and Asante NaTRIUM Green-1/2 (26), most of them are not selective for Na + over K + (22-25, 27, 28) or have a low binding affinity for Na + (with a K d higher than 100 mM) (25,(27)(28)(29)(30)(31). Furthermore, the presence of organic solvents is frequently required to achieve the desired sensitivity and selectivity for many of the Na + probes (32)(33)(34), making it difficult to study Na + under physiological conditions.…”

mentioning

confidence: 99%

In vitro selection of a sodium-specific DNAzyme and its application in intracellular sensing

Torabi¹,

Wu²,

McGhee³

et al. 2015

Proc. Natl. Acad. Sci. U.S.A.

304

286

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Over the past two decades, enormous progress has been made in designing fluorescent sensors or probes for divalent metal ions. In contrast, the development of fluorescent sensors for monovalent metal ions, such as sodium (Na + ), has remained underdeveloped, even though Na + is one the most abundant metal ions in biological systems and plays a critical role in many biological processes. Here, we report the in vitro selection of the first (to our knowledge) Na + -specific, RNA-cleaving deoxyribozyme (DNAzyme) with a fast catalytic rate [observed rate constant (k obs ) ∼0.1 min −1 ], and the transformation of this DNAzyme into a fluorescent sensor for Na + by labeling the enzyme strand with a quencher at the 3′ end, and the DNA substrate strand with a fluorophore and a quencher at the 5′ and 3′ ends, respectively. The presence of Na + catalyzed cleavage of the substrate strand at an internal ribonucleotide adenosine (rA) site, resulting in release of the fluorophore from its quenchers and thus a significant increase in fluorescence signal. The sensor displays a remarkable selectivity (>10,000-fold) for Na + over competing metal ions and has a detection limit of 135 μM (3.1 ppm). Furthermore, we demonstrate that this DNAzyme-based sensor can readily enter cells with the aid of α-helical cationic polypeptides. Finally, by protecting the cleavage site of the Na + -specific DNAzyme with a photolabile o-nitrobenzyl group, we achieved controlled activation of the sensor after DNAzyme delivery into cells. Together, these results demonstrate that such a DNAzyme-based sensor provides a promising platform for detection and quantification of Na + in living cells.M etal ions play crucial roles in a variety of biochemical processes. As a result, the concentrations of cellular metal ions have to be highly regulated in different parts of cells, as both deficiency and surplus of metal ions can disrupt normal functions (1-4). To better understand the functions of metal ions in biology, it is important to detect metal ions selectively in living cells; such an endeavor will not only result in better understanding of cellular processes but also novel ways to reprogram these processes to achieve novel functions for biotechnological applications.Among the metal ions in cells, sodium (Na + ) serves particularly important functions, as changes in its concentrations influence the cellular processes of numerous living organisms and cells (5-8), such as epithelial and other excitable cells (9). As one of the most abundant metal ions in intracellular fluid (10), Na + affects cellular processes by triggering the activation of many signal transduction pathways, as well as influencing the actions of hormones (11). Therefore, it is important to carefully monitor the concentrations of Na + in cells. Toward this goal, instrumental analyses by atomic absorption spectroscopy (12), Xray fluorescence microscopy (13), and 23 Na NMR (14) have been used to detect the concentration of intracellular Na + . However, it is difficult to use these methods to o...

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mentioning

confidence: 99%

In vitro selection of a sodium-specific DNAzyme and its application in intracellular sensing

Torabi¹,

Wu²,

McGhee³

et al. 2015

Proc. Natl. Acad. Sci. U.S.A.

304

286

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“…To date, changes in physiological parameters (for example, histamine38, glucose39, sodium40 or lithium41 levels) remotely measured using different types of immobilised fluorescent sensors in mice were only intentionally induced by researchers via injections of the respective substances. In other words, no observation of the shift in a physiological parameter has been made under indirect influences, such as stress.…”

Section: Discussionmentioning

confidence: 99%

Remote in vivo stress assessment of aquatic animals with microencapsulated biomarkers for environmental monitoring

Gurkov

Shchapova

Bedulina

et al. 2016

Sci Rep

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Remote in vivo scanning of physiological parameters is a major trend in the development of new tools for the fields of medicine and animal physiology. For this purpose, a variety of implantable optical micro- and nanosensors have been designed for potential medical applications. At the same time, the important area of environmental sciences has been neglected in the development of techniques for remote physiological measurements. In the field of environmental monitoring and related research, there is a constant demand for new effective and quick techniques for the stress assessment of aquatic animals, and the development of proper methods for remote physiological measurements in vivo may significantly increase the precision and throughput of analyses in this field. In the present study, we apply pH-sensitive microencapsulated biomarkers to remotely monitor the pH of haemolymph in vivo in endemic amphipods from Lake Baikal, and we compare the suitability of this technique for stress assessment with that of common biochemical methods. For the first time, we demonstrate the possibility of remotely detecting a change in a physiological parameter in an aquatic organism under ecologically relevant stressful conditions and show the applicability of techniques using microencapsulated biomarkers for remote physiological measurements in environmental monitoring.

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“…Optode nanosensors are composed of a hydrophobic, plasticized polymer core that contains hydrophobic sensor components and a polyethylene glycol (PEG) coating for solubility and biocompatibility. The sensors are approximately 100 nm in diameter, and specific nanosensor formulations that emit a reversible, concentration-dependent fluorescent signal for specific ions (Na + ) or glucose in vivo are already published 9, 14, 15 . The nanosensors are small enough for a simple subcutaneous injection, and their transdermal fluorescent signal is measurable with commercially-available animal imaging systems.…”

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Phosphorescent Nanosensors for in Vivo Tracking of Histamine Levels

Cash

Clark

2013

Anal. Chem.

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Continuously tracking bio-analytes in vivo will enable clinicians and researchers to profile normal physiology and monitor diseased states. Current in vivo monitoring system designs are limited by invasive implantation procedures and bio-fouling, limiting the utility of these tools for obtaining physiologic data. In this work, we demonstrate the first success in optically tracking histamine levels in vivo using a modular, injectable sensing platform based on a diamine oxidase and a phosphorescent oxygen nanosensor. Our new approach increases the range of measureable analytes by combining an enzymatic recognition element with a reversible nanosensor capable of measuring the effects of enzymatic activity. We use these enzyme nanosensors (EnzNS) to monitor the in vivo histamine dynamics as the concentration rapidly increases and decreases due to administration and clearance. The EnzNS system measured kinetics that match those reported from ex vivo measurements. This work establishes a modular approach to in vivo nanosensor design for measuring a broad range of potential target analytes. Simply replacing the recognition enzyme, or both the enzyme and nanosensor, can produce a new sensor system capable of measuring a wide range of specific analytical targets in vivo.

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In vivosodium concentration continuously monitored with fluorescent sensors

Cited by 41 publications

References 41 publications

In vitro selection of a sodium-specific DNAzyme and its application in intracellular sensing

In vitro selection of a sodium-specific DNAzyme and its application in intracellular sensing

Remote in vivo stress assessment of aquatic animals with microencapsulated biomarkers for environmental monitoring

Phosphorescent Nanosensors for in Vivo Tracking of Histamine Levels

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