Intracellular K$^+$ Determination With a Potentiometric Microelectrode Based on ZnO Nanowires

Ali, Syed M. Usman; Asif, Muhammad; Fulati, A.; Nur, Omer; Willander, Magnus; Brännmark, Cecilia; Strålfors, Peter; Englund, Ulrika H.; Elinder, Fredrik; Danielsson, Bengt

doi:10.1109/tnano.2010.2089696

Cited by 30 publications

(20 citation statements)

References 45 publications

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“…ϩ -selective Microelectrodes-The K ϩ -selective microelectrodes were fabricated as described previously (7). Briefly, ZnO nanorods were chemically grown on the tip of a borosilicate glass capillary in an aqueous solution of Zn(NO 3 ) 2 ⅐ 6H 2 O.…”

Section: Fabrication Of Kmentioning

confidence: 99%

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Intracellular K+ Concentration Decrease Is Not Obligatory for Apoptosis

Börjesson

Englund

Asif

et al. 2011

Journal of Biological Chemistry

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Section: Fabrication Of Kmentioning

confidence: 99%

“…We have previously designed a K ϩ -selective ZnO nanorodcovered microelectrode and reported on its stability when measuring intracellular K ϩ concentrations (7). The significant physiological role of altered intracellular K ϩ , however, makes it important also to be able to detect changes in intracellular K ϩ .…”

mentioning

confidence: 99%

Intracellular K+ Concentration Decrease Is Not Obligatory for Apoptosis

Börjesson

Englund

Asif

et al. 2011

Journal of Biological Chemistry

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“…Moreover, due to the unique properties of nanostructures/nanomaterials in the biosensing area, nanosensors offer some significant advantages owing to their small size and high surface area to volume ratios allowing larger signals, better catalysis and the more rapid movement of analytes through sensors. Recently, nanostructured materials such as zinc oxide (ZnO) [10][11][12][13][14], cerium oxide (CeO 2 ) [15], tin oxide (SnO 2 ) [16], titanium oxide (TiO 2 ) [17], iron oxide (FeO 2 ) [18] and zirconium oxide (ZrO 2 ) nanoparticles [19] have been used for fabrication of transducer surface because of their unique ability to promote faster electron transfer between electrode and active site of desired enzyme. Among these nanomaterials, ZnO nanostructures receive growing attention due to their unique properties including high specific surface area, high catalytic efficiency, strong adsorption ability, high isoelectric point (IEP 9.5), wide band gap (3.37 eV), biocompatibility and high electron communication features.…”

Section: Introductionmentioning

confidence: 99%

Selective determination of urea using urease immobilized on ZnO nanowires

Ali

Ibupoto

Salman³

et al. 2011

Sensors and Actuators B: Chemical

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Well-aligned zinc oxide (ZnO) nanowire arrays were fabricated on gold-coated plastic substrates using a low-temperature aqueous chemical growth (ACG) method. The ZnO nanowire arrays with 50-130 nm diameters and ~1 µm in lengths were used in an enzymebased urea sensor through immobilization of the enzyme urease that was found to be sensitive to urea concentrations from 0.1 mM to 100 mM. Two linear sensitivity regions were observed when the electrochemical responses (EMF) of the sensors were plotted vs. the logarithmic concentration range of urea from 0.1 mM to 100 mM. The proposed sensor showed a sensitivity of 52.8 mV/decade for 0.1-40 mM urea and a fast response time less than 4 s was achieved with good selectivity, reproducibility and negligible response to common interferents such as ascorbic acid and uric acid, glucose, K + and Na + ions.Index Terms: ZnO-nanowire arrays, electrochemical nanodevices, urease enzyme and urea determination.

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“…1). The second method was to measure the concentration directly by a K + -selective microelectrode, which we have developed in collaboration with another research group at Linköping University, Sweden (Usman Ali et al, 2011). The two methods gave similar results, suggesting that they could be used interchangeably (grey bars in Fig.…”

Section: Resultsmentioning

confidence: 99%

“…2 I is the current, and V is the absolute membrane voltage. To quantify the conductance data we used the Boltzmann equation Construction of a nanorod microelectrode for intracellular K + concentration measurements A ZnO-nanorod microelectrode which measures the intracellular K + concentration was developed and tested in collaboration with Magnus Willander's group at the Department of Science and Technology (Linköping University) (Usman Ali et al, 2011). ZnO nanorods were chemically grown on the tip of a borosilicate glass capillary in an aqueous solution of Zn(NO 3 ) 2 • 6H 2 O.…”

Section: Ethical Considerationsmentioning

confidence: 99%

The role of ion channels and intracellular metal ions in apoptosis of Xenopus oocytes

Englund¹

2014

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Apoptosis is one type of programmed cell death, important during tissue development and to maintain the tissue homeostasis. Apoptosis comprises a complex network of internal signaling pathways, and an important part of this signaling network is the action of voltage‐gated ion channels. The aim of this thesis was to explore the role of ion channels and the role of intracellular metal ions during apoptosis in Xenopus laevis oocytes. The reasons for using these oocytes are that they are large, robust, easy to handle, and easy to study electrophysiologically. Apoptosis was induced either chemically by incubation of the oocytes in staurosporine (STS) or mechanically by centrifugation of the oocytes. Ion currents were measured by a two‐electrode voltage clamp technique, intracellular ion concentrations were measured either directly by in‐house developed K+‐selective microelectrodes or indirectly by the electrophysiological technique, and apoptosis was measured by caspase‐3 activation. Paper I describes that the intracellular K+ concentration was reduced by about 30 % during STS‐induced apoptosis. However, this reduction was prevented by excessive expression of exogenous ion channels. Despite the magnitude of the intracellular K+ concentration, either normal or reduced level, the oocytes displayed normal signs of apoptosis, suggesting that the intracellular K+ reduction was not required for the apoptotic process. Because the intracellular K+ concentration was not critical for apoptosis we searched for other ion fluxes by exploring the electrophysiological properties of X. laevis oocytes. Paper II, describes a non‐inactivating Na+ current activated at positive membrane voltages that was upregulated by a factor of five during STS‐induced apoptosis. By preventing influx of Na+, the apoptotic signaling network involving capsase‐3 was prevented. To molecularly identify this voltage‐gated Na channel, the X. tropicalis genome and conserved regions of the human SCNA genes were used as a map. Paper III, shows that the voltage‐gated Na channel corresponds to the SCN2A gene ortholog and that supression of this SCN2A ortholog using miRNA prevented cell death. In conclusion, this thesis work demonstrated that a voltage‐gated Na channel is critical for the apoptotic process in X. laevis oocytes by increasing the intracellular Na+ concentration

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Intracellular K$^+$ Determination With a Potentiometric Microelectrode Based on ZnO Nanowires

Cited by 30 publications

References 45 publications

Intracellular K+ Concentration Decrease Is Not Obligatory for Apoptosis

Intracellular K+ Concentration Decrease Is Not Obligatory for Apoptosis

Selective determination of urea using urease immobilized on ZnO nanowires

The role of ion channels and intracellular metal ions in apoptosis of Xenopus oocytes

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