In the June issue of Physics World, Paul O’Shea, a biophysicist at the University of Nottingham, Michael Somekh, an optical engineer at Nottingham’s Institute of Biophysics, Imaging & Optical Science, and William Barnes, professor of photonics at the University of Exeter, outline these new techniques and explore why their development is an endeavour that requires the best efforts of both biologists and physicists.
The traditional division between the disciplines has found common ground in the effort to image cellular functions. While some living cells are larger than 80 micrometres across, important and interesting cellular processes - such as signalling between cells - can take place at length scales of less than one micrometre.
This poses serious challenges for traditional imaging techniques such as fluorescence microscopy, whereby optical microscopes are used to observe biological structures that have been tagged with fluorescent molecules that emit photons when irradiated with light of a specific wavelength, as these offer a resolution of at best 200 nanometres. Increasingly, biologists have turned to physicists for help in breaking through this “diffraction” limit.
The result has been the development in recent years of several novel techniques to extend the reach of fluorescence microscopy. These include methods such as stimulated emission depletion microscopy (STED), stochastic reconstruction microscopy (STORM), photo-activated localization microscopy (PALM) and structured illumination microscopy, all of which are capable of resolving structures as small as 50 nanometres across. These techniques build on theoretical and experimental tools common to physics that allow the physical diffraction limits of light to be broken.
As the authors of the article explain, “What is fascinating is that the experimental needs of biology are driving developments in imaging technology, while advances in imaging technology are in turn inspiring new biological questions. Many of these developments are also going hand in hand with a revolution that is taking place in biological thinking, which intimately involves physicists.”
Also in this issue:
• Physics World looks at how experiments on B-mesons using the LHCb detector at CERN’s Large Hadron Collider could provide the facility with its first discoveries
• A century after Henri Becquerel’s death, Physics World explores the role of serendipity in science and whether his discovery of radioactivity was down to luck or genius
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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...
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...
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...
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....
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...
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