Forum for Science, Industry and Business

Sponsored by:     3M 
Search our Site:

 

The first precise measurement of a single molecule's effective charge

15.01.2018

For the first time, scientists have precisely measured the effective electrical charge of a single molecule in solution. This fundamental insight of an SNSF Professor could also pave the way for future medical diagnostics.

Electrical charge is one of the key properties that allows molecules to interact. Life itself depends on this phenomenon: many biological processes involve interactions between molecules like proteins, where their charge plays an essential role. Yet, the charge of a protein in an aqueous environment – its natural context in a living organism – is hard to determine accurately using traditional approaches.


Scientists can determine the effective electrical charge of a molecule by trapping it in a potential well by measuring how long it stays inside.

© Madhavi Krishnan / University of Zurich

Madhavi Krishnan, who holds an SNSF professorship at the University of Zurich, has developed a method to precisely measure the charge of a single molecule in solution. Her advance was described in a series of articles in Nature Nanotechnology, Physical Review E and the Journal of Chemical Physics.

This discovery could pave the way to new diagnostic tools since, at a chemical level, many diseases are linked to a shift in a protein's electrical charge, which prevents the molecule from acting the way it should.

A molecule's electrical charge can be quite different in the gas phase and in solution. The reason for this difference lies in complex interactions between the object and the surrounding liquid. Hence, standard gas-phase measurements do not directly yield information on the molecule's behaviour in its biological context.

"Like kids kicking a ball"

Molecules in solution are in constant motion, randomly kicking each other. Krishnan and PhD student Francesca Ruggeri took advantage of this well-known phenomenon, called Brownian motion, in order to measure the effective charge of a molecule directly in solution.

First, they trapped the molecule in a "potential well". Rather than an actual well, this is a situation where the potential energy of the molecule is at its minimum. In such a situation, bouncing water molecules continuously attempt to expel the molecule from the well.

"It is like kids playing with a ball at the bottom of a pit," explains Krishnan. "The ball is the molecule we are interested in, and the children are the water molecules. The ball would have to receive quite a hard kick in order to fly out of the pit."

The higher the effective charge of the molecule, the greater the depth of the potential well and, consequently, the lower the likelihood that the molecule is ejected from the well. In practice, this means that the time needed for the molecule to be kicked out of the well is directly related to its effective charge.

"Ultimately it boils down to a statistical principle," explains Krishnan. "If we know how long a molecule remains trapped in the well, we know precisely how deep the well is. And since this depth depends directly on the molecule's effective charge, we can deduce this value very precisely too."

Two glass plates

In order to create a potential well, scientists compressed a solution containing the proteins between two glass plates, one of them being covered with microscopic holes. Molecules trapped in potential wells were labelled with fluorescent agents, which allowed them to be tracked with an optical microscope.

While the discovery has important fundamental implications, it could also pave the way towards novel diagnostic tools for many diseases caused by misshaped proteins, such as Alzheimer's and cancers. "We know that the 3D conformation of a protein influences its effective charge, and our work might present a novel route to detecting defective proteins."

F. Ruggeri et al.: Single-molecule electrometry. Nature Nanotechnology (2017) doi:10.1038/nnano.2017.26 https://www.bioc.uzh.ch/schuler/assets/ruggeri17krishnan.pdf

M. Krishnan: A Simple Model for Electrical Charge in Globular Macromolecules and Linear Polyelectrolytes in Solution. Journal of Chemical Physics (2017) doi:10.1063/1.4983485 http://aip.scitation.org/doi/pdf/10.1063/1.4983485

F. Ruggeri and M. Krishnan: Spectrally resolved single-molecule electrometry. Journal of Chemical Physics (2017) doi.org/10.1063/1.5008936 http://aip.scitation.org/doi/pdf/10.1063/1.5008936

F. Ruggeri and M. Krishnan: Lattice diffusion of a single molecule in solution. Physical Review E (2017) doi:10.1103/PhysRevE.96.062406
(Available to journalists as a PDF file from the SNSF: com@snf.ch)


Promoting young researchers

The SNSF has launched a new funding scheme to support researchers working towards a professorship. SNSF Eccellenza Grants allow tenure-track assistant professors to form a new research team and lead an ambitious scientific project. SNSF Eccellenza Professorial Fellowships cover the salaries of assistant professors as well as their project costs. The new scheme replaces the SNSF professorship grant, which has supported 691 researchers since its launch in 2000. And it has done so with great success: approx. 80% of grantees went on to obtain a professorship at a higher education institution in Switzerland or abroad.

http://www.snf.ch/en/funding/careers/eccellenza/Pages/default.aspx

Contact

Prof. Madhavi Krishnan
Department of Chemistry
University of Zurich
Winterthurerstrasse 190
CH-8057 Zurich
Telephone: +41 44 635 44 65
Email: madhavi.krishnan@uzh.ch

Weitere Informationen:

http://www.snf.ch/en/researchinFocus/newsroom/Pages/news-180115-press-release-fi...
http://p3.snf.ch/Project-166244 'SNSF Project "New experimental concepts in the manipulation of matter at the nanoscale"'
http://www.snf.ch/SiteCollectionImages/Medienmitteilungen/mm-180115-erste-messun... 'Download-image'

Medien - Abteilung Kommunikation | idw - Informationsdienst Wissenschaft

More articles from Life Sciences:

nachricht NYSCF researchers develop novel bioengineering technique for personalized bone grafts
18.07.2018 | New York Stem Cell Foundation

nachricht Pollen taxi for bacteria
18.07.2018 | Technische Universität München

All articles from Life Sciences >>>

The most recent press releases about innovation >>>

Die letzten 5 Focus-News des innovations-reports im Überblick:

Im Focus: First evidence on the source of extragalactic particles

For the first time ever, scientists have determined the cosmic origin of highest-energy neutrinos. A research group led by IceCube scientist Elisa Resconi, spokesperson of the Collaborative Research Center SFB1258 at the Technical University of Munich (TUM), provides an important piece of evidence that the particles detected by the IceCube neutrino telescope at the South Pole originate from a galaxy four billion light-years away from Earth.

To rule out other origins with certainty, the team led by neutrino physicist Elisa Resconi from the Technical University of Munich and multi-wavelength...

Im Focus: Magnetic vortices: Two independent magnetic skyrmion phases discovered in a single material

For the first time a team of researchers have discovered two different phases of magnetic skyrmions in a single material. Physicists of the Technical Universities of Munich and Dresden and the University of Cologne can now better study and understand the properties of these magnetic structures, which are important for both basic research and applications.

Whirlpools are an everyday experience in a bath tub: When the water is drained a circular vortex is formed. Typically, such whirls are rather stable. Similar...

Im Focus: Breaking the bond: To take part or not?

Physicists working with Roland Wester at the University of Innsbruck have investigated if and how chemical reactions can be influenced by targeted vibrational excitation of the reactants. They were able to demonstrate that excitation with a laser beam does not affect the efficiency of a chemical exchange reaction and that the excited molecular group acts only as a spectator in the reaction.

A frequently used reaction in organic chemistry is nucleophilic substitution. It plays, for example, an important role in in the synthesis of new chemical...

Im Focus: New 2D Spectroscopy Methods

Optical spectroscopy allows investigating the energy structure and dynamic properties of complex quantum systems. Researchers from the University of Würzburg present two new approaches of coherent two-dimensional spectroscopy.

"Put an excitation into the system and observe how it evolves." According to physicist Professor Tobias Brixner, this is the credo of optical spectroscopy....

Im Focus: Chemical reactions in the light of ultrashort X-ray pulses from free-electron lasers

Ultra-short, high-intensity X-ray flashes open the door to the foundations of chemical reactions. Free-electron lasers generate these kinds of pulses, but there is a catch: the pulses vary in duration and energy. An international research team has now presented a solution: Using a ring of 16 detectors and a circularly polarized laser beam, they can determine both factors with attosecond accuracy.

Free-electron lasers (FELs) generate extremely short and intense X-ray flashes. Researchers can use these flashes to resolve structures with diameters on the...

All Focus news of the innovation-report >>>

Anzeige

Anzeige

VideoLinks
Industry & Economy
Event News

Leading experts in Diabetes, Metabolism and Biomedical Engineering discuss Precision Medicine

13.07.2018 | Event News

Conference on Laser Polishing – LaP: Fine Tuning for Surfaces

12.07.2018 | Event News

11th European Wood-based Panel Symposium 2018: Meeting point for the wood-based materials industry

03.07.2018 | Event News

 
Latest News

Machine-learning predicted a superhard and high-energy-density tungsten nitride

18.07.2018 | Materials Sciences

NYSCF researchers develop novel bioengineering technique for personalized bone grafts

18.07.2018 | Life Sciences

Why might reading make myopic?

18.07.2018 | Health and Medicine

VideoLinks
Science & Research
Overview of more VideoLinks >>>