In order to observe the individual particles in a solution, Prof. Madhavi Krishnan and her co-workers «entice» each particle into an «electrostatic trap». It works like this: between two glass plates the size of a chip, the researchers create thousands of round energy holes. The trick is that these holes have just a weak electrostatic charge. The scientists than add a drop of the solution to the plates, whereupon each particle falls into an energy hole and remains trapped there. But the particles do not remain motionless in their trap. Instead, molecules in the solution collide with them continuously, causing the particles to move in a circular motion. «We measure these movements, and are then able to determine the charge of each individual particle», explains Prof. Madhavi Krishnan.
Put simply, particles with just a small charge make large circular movements in their traps, while those with a high charge move in small circles. This phenomenon can be compared to that of a light-weight ball which, when thrown, travels further than a heavy one. The US physicist Robert A. Millikan used a similar method 100 years ago in his oil drop experiment to determine the velocity of electrically charged oil drops. In 1923, he received the Nobel Prize in physics in recognition of his achievements. «But he examined the drops in a vacuum», Prof. Krishnan explains. «We on the other hand are examining nano particles in a solution which itself influences the properties of the particles».
Electrostatic charge of «nano drugs packages»
For all solutions manufactured industrially, the electrical charge of the nano particles contained therein is also of primary interest, because it is the electrical charge that allows a fluid solution to remain stable and not to develop a lumpy consistency. «With our new method, we get a picture of the entire suspension along with all of the particles contained in it», emphasizes Prof. Madhavi Krishnan. A suspension is a fluid in which miniscule particles or drops are finely distributed, for example in milk, blood, various paints, cosmetics, vaccines and numerous pharmaceuticals. «The charge of the particles plays a major role in this», the Zurich-based scientist tells us.
One example is the manufacture of medicines that have to be administered in precise doses over a longer period using drug-delivery systems. In this context, nano particles act as «packages» that transport the drugs to where they need to take effect. Very often, it is their electrical charge that allows them to pass through tissue and cell membranes in the body unobstructed and so to take effect. «That's why it is so important to be able to measure their charge. So far most of the results obtained have been imprecise», the researcher tells us.
«The new method allows us to even measure in real-time a change in the charge of a single entity», adds Prof. Madhavi Krishnan. «This is particularly exciting for basic research and has never before been possible». This is because changes in charge play a role in all bodily reactions, whether in proteins, large molecules such as the DNA double helix, where genetic make-up is encoded, or cell organelles. «We're examining how material works in the field of millionths of a millimeter».
University of Zurich: http://www.uzh.ch
This press release was posted to serve as a topic for discussion. Please comment below. We try our best to only post press releases that are associated with peer reviewed scientific literature. Critical discussions of the research are appreciated. If you need help finding a link to the original article, please contact us on twitter or via e-mail.
So much of the food we eat these days is encased in plastic. And behind it is a whole lot of research and innovation. We dive into some of the materials that keep food fresh and portable.
Researchers at MIT have created a ball with a customizable surface texture through the science of wrinkling.
A new way of turning vegetable waste directly into bioplastics could make such materials even more environmentally friendly
A 2-billion-year-old rock has revealed the first evidence of the isolated pockets where oxygen-breathing life may have evolved
A series of explosions set off by a team of scientists were expected to rattle Washington state's Mount St. Helens on Wednesday as researchers map the interior of the volcano, whose 1980 eruption was the deadliest in U.S. history.
Researchers say the right mix of erosion and stress creates Earth’s natural sandstone arches and columns
Michael Slezak goes deep under the outback to find a home for the southern hemisphere's first WIMP detector, which could confirm our best direct signal yet
Pick the right plastic off a refuse tip, then shred, melt and convert it into feedstock for 3D printers – it's a living for some of India's poorest people
Sky surveys suggest that dark matter or some other mysterious dark material may be lighting up the universe with too much ultraviolet radiation
Rare particle scattering detected at CERN may help test how the Higgs boson imparts mass to other particles – and perhaps lead to new physics