In collaboration with colleagues from Berlin and Madrid, researchers at the Department of Physics at the University of Basel have pulled up isolated molecular chains from a gold surface, using the tip of an atomic force microscope (AFM). The observed signal provides insight into the detachment force and binding energy of molecules. The results have been published in the renowned scientific journal PNAS.
Atomic force microscopy is a method normally used for imaging matter with very high resolution. The sharp tip of the microscope is used to scan the surface line by line. The resolution is so high, that single atoms can be seen.
“This method is roughly equivalent to using the tip of the Matterhorn to scan the surface of a tennis ball”, says Prof. Ernst Meyer of the Department for Physics at the University of Basel. Due to an improved method, the scientists are now able to investigate the mechanical behavior of a single polymer being pulled off a surface.
Using the tip of the AFM, the researchers were able to pull single chains of molecules (polymers) off a gold surface. “The molecule-surface interaction during pulling is so weak that each chain link (molecular unit) detaches successively.
Thus, the whole chain can be pulled off almost vertically to the surface”, explains Meyer. By analyzing the observed oscillations, the researchers are able to make quantitative statements on the binding energy of each molecular unit.
Motion without friction
Furthermore, the experiments showed that the polymers could be pulled off with almost no lateral forces. This remarkable behavior of nearly frictionless motion was predicted by a theoretical model and has now been verified for molecules on a gold surface.
Previously, the mechanical behavior of single polymer during pulling from a surface had never been investigated with atomic-scale resolution. The findings and calculations of the research team now provide detailed insight into this process for the first time.
Such investigations are not only of interest for the field of physics, but also for biology and chemistry, since the method of pulling polymers from surfaces can also be applied to biological molecules. So far, valuable insights have been obtianed into the folding and unfolding of DNA and proteins. Chemical reactions of small biopolymer sub units or complex polymer chains under the influence of traction forces and catalytic nanoparticles could be investigated with this new method.
Shigeki Kawai, Matthias Koch, Enrico Gnecco, Ali Sadeghi, Rémy Pawlak, Thilo Glatzel, Jutta Schwarz, Stefan Goedecker, Stefan Hecht, Alexis Baratoff, Leonhard Grill and Ernst Meyer
Quantifying the atomic-level mechanics of single long physisorbed molecular chains
PNAS Early Edition | doi: 10.1073/pnas.1319938111
Prof. Ernst Meyer, University of Basel, Department of Physics, phone: +41 61 267 37 24, email: firstname.lastname@example.org
Olivia Poisson | Universität Basel
Graphene microphone outperforms traditional nickel and offers ultrasonic reach
27.11.2015 | Institute of Physics
Tracking down the 'missing' carbon from the Martian atmosphere
25.11.2015 | California Institute of Technology
Planet Earth experienced a global climate shift in the late 1980s on an unprecedented scale, fuelled by anthropogenic warming and a volcanic eruption, according to new research published this week.
Scientists say that a major step change, or ‘regime shift’, in the Earth’s biophysical systems, from the upper atmosphere to the depths of the ocean and from...
The Fraunhofer Institute for Solar Energy Systems ISE has installed 70 photovoltaic modules on the outer façade of one of its lab buildings. The modules were...
Nerve cells cover their high energy demand with glucose and lactate. Scientists of the University of Zurich now provide new support for this. They show for the first time in the intact mouse brain evidence for an exchange of lactate between different brain cells. With this study they were able to confirm a 20-year old hypothesis.
In comparison to other organs, the human brain has the highest energy requirements. The supply of energy for nerve cells and the particular role of lactic acid...
In laser material processing, the simulation of processes has made great strides over the past few years. Today, the software can predict relatively well what will happen on the workpiece. Unfortunately, it is also highly complex and requires a lot of computing time. Thanks to clever simplification, experts from Fraunhofer ILT are now able to offer the first-ever simulation software that calculates processes in real time and also runs on tablet computers and smartphones. The fast software enables users to do without expensive experiments and to find optimum process parameters even more effectively.
Before now, the reliable simulation of laser processes was a job for experts. Armed with sophisticated software packages and after many hours on computer...
Researchers at Heidelberg University have devised a new way to study the phenomenon of magnetism. Using ultracold atoms at near absolute zero, they prepared a...
25.11.2015 | Event News
17.11.2015 | Event News
21.10.2015 | Event News
27.11.2015 | Press release
27.11.2015 | Life Sciences
27.11.2015 | Materials Sciences