scholarly journals DNA Aptamer Functionalized Hydrogels for Interferometric Fiber-Optic Based Continuous Monitoring of Potassium Ions

Biosensors ◽  
2021 ◽  
Vol 11 (8) ◽  
pp. 266
Author(s):  
Nataša Žuržul ◽  
Bjørn Torger Stokke
Keyword(s):  
Conformational Transition ◽  
Polymer Network ◽  
Potassium Ion ◽  
Ion Concentration ◽  
Dna Aptamer ◽  
Blood Levels ◽  
Label Free ◽  
Practical Applications ◽  
Hydrogel Matrix ◽  
K Concentration

In the present paper, we describe a potassium sensor based on DNA-aptamer functionalized hydrogel, that is capable of continuous label-free potassium ion (K+) monitoring with potential for in situ application. A hydrogel attached to the end of an optical fiber is designed with di-oligonucleotides grafted to the polymer network that may serve as network junctions in addition to the covalent crosslinks. Specific affinity toward K+ is based on exploiting a particular aptamer that exhibits conformational transition from single-stranded DNA to G-quadruplex formed by the di-oligonucleotide in the presence of K+. Integration of this aptamer into the hydrogel transforms the K+ specific conformational transition to a K+ concentration dependent deswelling of the hydrogel. High-resolution interferometry monitors changes in extent of swelling at 1 Hz and 2 nm resolution for the hydrogel matrix of 50 µm. The developed hydrogel-based biosensor displayed high selectivity for K+ ions in the concentration range up to 10 mM, in the presence of physiological concentrations of Na+. Additionally, the concentration dependent and selective K+ detection demonstrated in the artificial blood buffer environment, both at room and physiological temperatures, suggests substantial potential for practical applications such as monitoring of potassium ion concentration in blood levels in intensive care medicine.

Viscoelasticity, Conformational Transition and Ultrastructure of Kappa-Carrageenan in the Presence of Potassium Ion around the Critical Total Ion Concentration

2008 ◽  
Author(s):  
María C. Núñez-Santiago ◽  
Alberto Tecante ◽  
Sylvie Durand ◽  
Catherine Garnier ◽  
Jean L. Doublier ◽  
...  
Keyword(s):  
Conformational Transition ◽  
Potassium Ion ◽  
Ion Concentration ◽  
Kappa Carrageenan

Selection of a DNA Aptamer against Zearalenone and Docking Analysis for Highly Sensitive Rapid Visual Detection with Label-Free Aptasensor

2018 ◽  
Vol 66 (45) ◽  
pp. 12102-12110 ◽  
Author(s):  
Yuanyuan Zhang ◽  
Taofeng Lu ◽  
Yue Wang ◽  
Chenxi Diao ◽  
Yan Zhou ◽  
...  
Keyword(s):  
Visual Detection ◽  
Dna Aptamer ◽  
Label Free ◽  
Docking Analysis ◽  
Highly Sensitive ◽  
Selection Of

scholarly journals In Vivo Neocortical [K]o Modulation by Targeted Stimulation of Astrocytes

2021 ◽  
Vol 22 (16) ◽  
pp. 8658
Author(s):  
Azin EbrahimAmini ◽  
Shanthini Mylvaganam ◽  
Paolo Bazzigaluppi ◽  
Mohamad Khazaei ◽  
Alexander Velumian ◽  
...  
Keyword(s):  
Nervous System ◽  
Membrane Potential ◽  
Potassium Ion ◽  
Ion Concentration ◽  
Extracellular Potassium ◽  
Spreading Depolarization ◽  
Potential Tool ◽  
Stimulation Of

A normally functioning nervous system requires normal extracellular potassium ion concentration ([K]o). Throughout the nervous system, several processes, including those of an astrocytic nature, are involved in [K]o regulation. In this study we investigated the effect of astrocytic photostimulation on [K]o. We hypothesized that in vivo photostimulation of eNpHR-expressing astrocytes leads to a decreased [K]o. Using optogenetic and electrophysiological techniques we showed that stimulation of eNpHR-expressing astrocytes resulted in a significantly decreased resting [K]o and evoked K responses. The amplitude of the concomitant spreading depolarization-like events also decreased. Our results imply that astrocytic membrane potential modification could be a potential tool for adjusting the [K]o.

scholarly journals Effect of enzymic (collagenase) harvesting on the intracellular Na+/K+ ratio of Swiss/3T3 cells as revealed by X-ray microanalysis

1988 ◽  
Vol 90 (1) ◽  
pp. 99-104
Author(s):  
Z. Szallasi ◽  
A. Szallasi ◽  
F. Bojan ◽  
I. Zs-Nagy
Keyword(s):  
Cell Cultures ◽  
Freeze Fracture ◽  
Ion Concentration ◽  
Bulk Specimen ◽  
X Ray ◽  
Dependent Cell ◽  
Swiss 3T3 ◽  
K Concentration ◽  
Post Harvesting ◽  
Swiss 3T3 Cell

Swiss/3T3 cell cultures were harvested with 0.05% collagenase and after centrifugation the pellet was prepared by the freeze-fracture/freeze-drying (FFFD) method for bulk-specimen X-ray microanalysis. Time-dependent variations in the intracellular monovalent elemental concentrations (Na+, K+ and Cl-) as well as of the Na+/K+ ratio were followed for 120 min subsequent to harvesting. The quantitative measurements revealed a very considerable increase in the intracellular Na+ and Cl- accompanied by a decrease in the K+ concentration as soon as 5 min after harvesting. The Na+/K+ ratio had increased by this time to about 1.5 on average. These changes indicate a sustained depolarization of the cell membrane. During the first 60 min this depolarization tended to normalize as demonstrated by an exponential decrease in the intracellular Na+ and Cl- and an increase in the K+ content involving a decrease in the Na+/K+ ratio. The total intracellular monovalent ion concentration remained almost constant during this post-harvesting period. These results suggest that harvesting represents a serious depolarizing stimulus to the cells, the consequences of which are restored only after 1–2h. These alterations should be taken into consideration during various experimental designs when using anchorage-dependent cell cultures.

THE INFLUENCE OF POTASSIUM ION UPON GLUCOSE UPTAKE AND GLYCOGEN SYNTHESIS IN THE ISOLATED RAT DIAPHRAGM

1955 ◽  
Vol 33 (1) ◽  
pp. 687-694 ◽  
Author(s):  
D. W. Clarke
Keyword(s):  
Glucose Uptake ◽  
Glycogen Synthesis ◽  
Potassium Ion ◽  
Ion Concentration ◽  
Rat Diaphragm ◽  
High Potassium ◽  
High Concentrations ◽  
Glycogen Breakdown ◽  
Isolated Rat

The amounts of glucose taken from a medium, and the amounts of glycogen synthesized, by rat hemidiaphragms were studied under various conditions. High concentrations of potassium ion inhibited the glucose uptake and there was also a reduced net glycogen synthesis. Glycogen breakdown was probably not increased by high potassium ion concentration. The effect of potassium was most marked when conditions were such that one would ordinarily expect a considerable glucose uptake or glycogen synthesis. The action of insulin was not peculiarly susceptible to potassium ion inhibition.

scholarly journals Aptamer Functionalized Lipid Multilayer Gratings for Label-Free Analyte Detection

Nanomaterials ◽  
2020 ◽  
Vol 10 (12) ◽  
pp. 2433
Author(s):  
Plengchart Prommapan ◽  
Nermina Brljak ◽  
Troy W. Lowry ◽  
David Van Winkle ◽  
Steven Lenhert
Keyword(s):  
Lipid Composition ◽  
Optical Biosensor ◽  
Optical Signal ◽  
Dna Aptamer ◽  
Critical Parameters ◽  
Label Free ◽  
Scale Thickness ◽  
Label Free Detection ◽  
Analyte Detection ◽  
Micrometer Scale

Lipid multilayer gratings are promising optical biosensor elements that are capable of transducing analyte binding events into changes in an optical signal. Unlike solid state transducers, reagents related to molecular recognition and signal amplification can be incorporated into the lipid grating ink volume prior to fabrication. Here we describe a strategy for functionalizing lipid multilayer gratings with a DNA aptamer for the protein thrombin that allows label-free analyte detection. A double cholesterol-tagged, double-stranded DNA linker was used to attach the aptamer to the lipid gratings. This approach was found to be sufficient for binding fluorescently labeled thrombin to lipid multilayers with micrometer-scale thickness. In order to achieve label-free detection with the sub-100 nm-thick lipid multilayer grating lines, the binding affinity was improved by varying the lipid composition. A colorimetric image analysis of the light diffracted from the gratings using a color camera was then used to identify the grating nanostructures that lead to an optimal signal. Lipid composition and multilayer thickness were found to be critical parameters for the signal transduction from the aptamer functionalized lipid multilayer gratings.

Porous CoC2O4/Graphene Oxide Nanocomposite for Advanced Potassium-Ion Storage

2019 ◽  
Vol 19 (6) ◽  
pp. 3610-3615 ◽  
Author(s):  
Lifeng Wang ◽  
Kaiyuan Wei ◽  
Pengjun Zhang ◽  
Hong Wang ◽  
Xiujun Qi ◽  
...  
Keyword(s):  
Graphene Oxide ◽  
Lithium Ion Batteries ◽  
Low Cost ◽  
Rate Capability ◽  
Lithium Ion ◽  
Potassium Ion ◽  
Practical Applications ◽  
Ion Storage ◽  
Cheap Method ◽  
Excellent Cycling Stability

Potassium-ion batteries (PIBs), as one of the alternatives to lithium-ion batteries (LIBs), have attracted considerable attention on account of the affluence and low-cost of potassium. Moreover, CoC2O4 and graphene oxide (GO) have been used very well in lithium-ion batteries. Hence, the hybrid CoC2O4/GO was investigated as a new anode material for PIBs. The hybrid CoC2O4/GO was synthesized by a facile and cheap method combined with supersonic dispersion. Electrochemical measurements reveal that the hybrid CoC2O4/GO delivered an excellent cycling stability of 166 mAh g−1 at 50 mA g−1 and a superior rate capability even at 1 A g−1. These results demonstrate although the cycle ability was insufficient for practical applications, transition-metal oxalates composites can still bring new hope to the development of PIBs.

scholarly journals Label-free profiling of DNA aptamer-small molecule binding using T5 exonuclease

2020 ◽  
Vol 48 (20) ◽  
pp. e120-e120 ◽  
Author(s):  
Obtin Alkhamis ◽  
Weijuan Yang ◽  
Rifat Farhana ◽  
Haixiang Yu ◽  
Yi Xiao
Keyword(s):  
Ligand Binding ◽  
Small Molecule ◽  
High Throughput ◽  
Dna Aptamer ◽  
Label Free ◽  
General Applicability ◽  
Gold Standard Method ◽  
Characterization Methods ◽  
Increased Risk

Abstract In vitro aptamer isolation methods can yield hundreds of potential candidates, but selecting the optimal aptamer for a given application is challenging and laborious. Existing aptamer characterization methods either entail low-throughput analysis with sophisticated instrumentation, or offer the potential for higher throughput at the cost of providing a relatively increased risk of false-positive or -negative results. Here, we describe a novel method for accurately and sensitively evaluating the binding between DNA aptamers and small-molecule ligands in a high-throughput format without any aptamer engineering or labeling requirements. This approach is based on our new finding that ligand binding inhibits aptamer digestion by T5 exonuclease, where the extent of this inhibition correlates closely with the strength of aptamer-ligand binding. Our assay enables accurate and efficient screening of the ligand-binding profiles of individual aptamers, as well as the identification of the best target binders from a batch of aptamer candidates, independent of the ligands in question or the aptamer sequence and structure. We demonstrate the general applicability of this assay with a total of 106 aptamer-ligand pairs and validate these results with a gold-standard method. We expect that our assay can be readily expanded to characterize small-molecule-binding aptamers in an automated, high-throughput fashion.

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