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195 results on '"Rant, Ulrich"'

18. Data analysis of translocation events in nanopore experiments

Author

Pedone, Daniel, Firnkes, Matthias, and Rant, Ulrich

Subjects
Electronic data processing -- Methods, Membranes (Technology) -- Electric properties, Membranes (Technology) -- Chemical properties, Membranes (Technology) -- Structure, Translocation (Genetics) -- Research, Chemistry
Abstract

Nanopores have become important tools for single molecule experiments, where information about the properties of DNA/RNA or proteins is inferred from current pulses elicited by individual molecules as they traverse a single pore. However, because of necessary electronic filters employed in the measurement technique, the extraction of meaningful information from short pulses is limited. This restricts the use of nanopores for the investigation of small molecules which cross the pore rapidly. Here we present a method which significantly improves the accuracy of the analysis of noise-filtered current pulses. We introduce improved criteria to measure the pulse width and propose a method to evaluate the pulse height from the falling edge of the pulse, which renders the identification of a pulse plateau unnecessary. The new methods are compared to conventional routines and validated by analyzing representative current pulses as well as experimental protein translocation data. It is demonstrated that the pulse properties can be recovered with satisfying accuracy beyond the usual limitations of Bessel filters, i.e., from pulses featuring a width of merely [0.3f.sup.-1.sub.c] ([f.sub.c] being the filter cutoff frequency). 10.1021/ac901877z

Published
2009

20. Silicon-on-insulator microfluidic device with monolithic sensor integration for [micro]TAS applications

Author

Sharma, Sanjiv, Buchholz, Karin, Luber, Sebastian M., Rant, Ulrich, Tornow, Marc, and Abstreiter, Gerhard

Subjects
Sensors -- Research, Field-effect transistors -- Research, Microelectromechanical systems -- Research, Engineering and manufacturing industries, Science and technology
Abstract

A novel concept for the integration of liquid phase charge sensors into microfluidic devices based on silicon-on-insulator (SOI) technology is reported. Utilizing standard silicon processing we fabricated basic microfluidic cross geometries comprising of 5-10-mm-long and 55-[micro]m-wide channels of 3 [micro]m depth by wet sacrificial etching of the buried oxide of an SOI substrate. To demonstrate the feasibility of fluid manipulation along the channel we performed electroosmotic pumping of a dye-labeled buffer solution. At selected positions along the channel we patterned the 205-nm thin top silicon layer into freely suspended, 10-[micro]m wide bars bridging the channel. We demonstrate how these monolithically integrated bars work as thin-film resistors that sensitively probe changes of the surface potential via the field effect. In this way, a combination of electrokinetic manipulation and separation of charged analytes together with an on-chip electronic detection can provide a new basis for the label-free analysis of, e.g., biomolecular species as envisaged in the concept of micrototal analysis systems ([micro]TAS) or Lab-on-Chip (LOC). [1484] Index Terms--Field-effect transistor [FET), lab-on-chip (LOC), microfluidics, micrototal analysis system ([micro]TAS), silicon-on-insulator (SOI).

Published
2006

27. Electrical Actuation of a DNA Origami Nanolever on an Electrode

Author

Kroener, Felix, Heerwig, Andreas, Kaiser, Wolfgang, Mertig, Michael, and Rant, Ulrich

Abstract

Development of electrically powered DNA origami nanomachines requires effective means to actuate moving origami parts by externally applied electric fields. We demonstrate how origami nanolevers on an electrode can be manipulated (switched) at high frequency by alternating voltages. Orientation switching is long-time stable and can be induced by applying low voltages of 200 mV. The mechanical response time of a 100 nm long origami lever to an applied voltage step is less than 100 μs, allowing dynamic control of the induced motion. Moreover, through voltage assisted capture, origamis can be immobilized from folding solution without purification, even in the presence of excess staple strands. The results establish a way for interfacing and controlling DNA origamis with standard electronics, and enable their use as moving parts in electro-mechanical nanodevices.

Published
2024
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32. Observation of electrostatically released DNA from gold electrodes with controlled threshold voltages.

Author

Takeishi, Shunsaku, Rant, Ulrich, Fujiwara, Tsuyoshi, Buchholz, Karin, Usuki, Tatsuya, Arinaga, Kenji, Takemoto, Kazuya, Yamaguchi, Yoshitaka, Tornow, Marc, Fujita, Shozo, Abstreiter, Gerhard, and Yokoyama, Naoki

Subjects
*DNA, *OLIGONUCLEOTIDES, *GOLD, *ELECTRODES, *FLUORESCENCE, *CYANIDES
Abstract

DNA oligo-nucleotides, localized at Au metal electrodes in aqueous solution, are found to be released when applying a negative bias voltage to the electrode. The release was confirmed by monitoring the intensity of the fluorescence of cyanine dyes (Cy3) linked to the 5[sup ′] end of the DNA. The threshold voltage of the release changes depending on the kind of linker added to the DNA 3[sup ′]-terminal. The amount of released DNA depends on the duration of the voltage pulse. Using this technique, we can retain DNA at Au electrodes or Au needles, and release the desired amount of DNA at a precise location in a target. The results suggest that DNA injection into living cells is possible with this method. © 2004 American Institute of Physics. [ABSTRACT FROM AUTHOR]

Published
2004
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33. Conformations of end-tethered DNA molecules on gold surfaces: influences of applied electric potential, electrolyte screening, and temperature

Author

Kaiser, Wolfgang and Rant, Ulrich

Subjects
DNA -- Structure, DNA -- Chemical properties, DNA -- Electric properties, Electric fields -- Usage, Voltage -- Measurement, Oligonucleotides -- Structure, Oligonucleotides -- Chemical properties, Chemistry
Abstract

The properties of 72mer oligonucleotides that are end-tethered to gold surfaces under the influence of applied electric fields are described. The experiments provide insight into an interesting temperature-dependent stiffening of single-stranded DNA at low ionic strength.

Published
2010

40. Electroosmotic Flow and Protein Trapping in Solid-State Nanopores

Author

Abstreiter, Gerhard (Prof. Dr.), Simmel, Friedrich (Prof. Dr.), Zacharias, Martin (Prof. Dr.), Rant, Ulrich (Dr.), Firnkes, Matthias, Abstreiter, Gerhard (Prof. Dr.), Simmel, Friedrich (Prof. Dr.), Zacharias, Martin (Prof. Dr.), Rant, Ulrich (Dr.), and Firnkes, Matthias

Abstract

This thesis covers the detection and analysis of proteins by means of solid-state nanopores in silicon nitride. Monitoring the ionic current through a single pore permits to detect the passage of single proteins, leaving a fingerprint in the current-time trace from which information about the molecule may be derived. In the first part, the influence of the electroosmotic flow on protein translocation is investigated. The zeta potential of pore and protein are determined independently. From the sign and magnitude of the potentials, the translocation direction under an applied electric field can be predicted. In the second part, we investigate proteasome molecules by translocation and by trapping of single molecules in a suitable pore geometry. The third part covers Nanoparticle-DNA conjugates, which are used to block the pore for a certain amount of time reversibly., Diese Arbeit behandelt die Detektion und Analyse von Proteinen mittels künstlicher Nanoporen in Silizium-Nitrid. Indem man den zeitlichen Verlauf des Ionenstroms durch eine einzelne Pore misst, kann man den Durchgang (Translokation) eines einzelnen Proteins durch die Pore sichtbar machen. Das Protein hinterlässt einen charakteristischen Fingerabdruck im Strom-Zeit Verlauf, anhand dessen man Informationen über das untersuchte Protein ableiten kann. Im ersten Teil der Arbeit wird der Einfluss des elektroosmotischen Flusses auf Protein Translokationen untersucht. Hierzu wird das Zeta-Potential der Nanopore und des Proteins bestimmt. Aus dem Verhältnis beider Potentiale können Aussagen über die zu erwartende Translokationsrichtung getroffen werden. Im zweiten Teil der Arbeit werden Translokationen von Proteasom-Molekülen untersucht sowie einzelne Moleküle in einer speziellen Pore gefangen. Der dritte Teil behandelt Nanopartikel-DNA Konjugate, die eine Pore für kurze Zeit reversibel verschließen können.

Published
2013

41. Electroosmotic Flow and Protein Trapping in Solid-State Nanopores

Author

Abstreiter, Gerhard (Prof. Dr.);Rant, Ulrich (Dr.), Abstreiter, Gerhard (Prof. Dr.);Simmel, Friedrich (Prof. Dr.);Zacharias, Martin (Prof. Dr.), Firnkes, Matthias, Abstreiter, Gerhard (Prof. Dr.);Rant, Ulrich (Dr.), Abstreiter, Gerhard (Prof. Dr.);Simmel, Friedrich (Prof. Dr.);Zacharias, Martin (Prof. Dr.), and Firnkes, Matthias

Abstract

This thesis covers the detection and analysis of proteins by means of solid-state nanopores in silicon nitride. Monitoring the ionic current through a single pore permits to detect the passage of single proteins, leaving a fingerprint in the current-time trace from which information about the molecule may be derived. In the first part, the influence of the electroosmotic flow on protein translocation is investigated. The zeta potential of pore and protein are determined independently. From the sign and magnitude of the potentials, the translocation direction under an applied electric field can be predicted. In the second part, we investigate proteasome molecules by translocation and by trapping of single molecules in a suitable pore geometry. The third part covers Nanoparticle-DNA conjugates, which are used to block the pore for a certain amount of time reversibly., Diese Arbeit behandelt die Detektion und Analyse von Proteinen mittels künstlicher Nanoporen in Silizium-Nitrid. Indem man den zeitlichen Verlauf des Ionenstroms durch eine einzelne Pore misst, kann man den Durchgang (Translokation) eines einzelnen Proteins durch die Pore sichtbar machen. Das Protein hinterlässt einen charakteristischen Fingerabdruck im Strom-Zeit Verlauf, anhand dessen man Informationen über das untersuchte Protein ableiten kann. Im ersten Teil der Arbeit wird der Einfluss des elektroosmotischen Flusses auf Protein Translokationen untersucht. Hierzu wird das Zeta-Potential der Nanopore und des Proteins bestimmt. Aus dem Verhältnis beider Potentiale können Aussagen über die zu erwartende Translokationsrichtung getroffen werden. Im zweiten Teil der Arbeit werden Translokationen von Proteasom-Molekülen untersucht sowie einzelne Moleküle in einer speziellen Pore gefangen. Der dritte Teil behandelt Nanopartikel-DNA Konjugate, die eine Pore für kurze Zeit reversibel verschließen können.

Published
2013

43. DNA Nanostructures for Electrophysiology

Author

Martin, Thomas G., primary, Wei, Ruoshan, additional, Langecker, Martin, additional, Arnaut, Vera, additional, List, Jonathan, additional, Renner, Stefan, additional, Mayer, Michael, additional, Rant, Ulrich, additional, Simmel, Friedrich C., additional, and Dietz, Hendrik, additional

Published
2013
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