Imaging speed is more important than resolution in the majority of cellular investigations, Dr Eric Betzig has said during a presentation made at the World of Photonics Congress in Munich on 21 June.
Betzig of the Howard Hughes Medical Institute in the USA and Professor Stefan Hell of the Max Planck Institute in Göttingen, Germany both gave lectures on super resolution microscopy, for which, along with W.E. Moerner, they won the Nobel Prize in Chemistry in 2014.
Betzig said that 90 per cent of biological studies would rather have the speed of a technique called lattice light sheet microscopy than extremely high resolution. High speed with little phototoxicity is required to capture sub-cellular processes in events like embryogenesis.
Betzig, Hell and Moerner won the 2014 Nobel Prize in Chemistry for their work on super resolution microscopy, for going beyond the diffraction limit of light microscopy. Stimulated emission depletion (STED) microscopy, which Hell developed, can reach 20nm to 40nm resolution, depending on the fluorescent molecule.
STED overcomes the diffraction barrier by exciting fluorescent molecules at one laser wavelength, but also turning off a subset of those molecules at another wavelength in order to distinguish between them. PicoQuant now offers commercial STED systems, which the company was displaying at Laser World of Photonics.
Hell said that, because of the mechanism by which STED operates, the emphasis now becomes the design of the fluorescent molecules in order to achieve higher spatial resolution, rather than the optical design.
However, the high spatial resolution provided by STED comes at a cost of phototoxicity, as the technique uses intense illumination. Betzig commented that techniques like structured illumination microscopy – a super resolution technique that wasn’t awarded the Nobel Prize – and lattice light sheet microscopy, which don’t have quite the spatial resolution of STED but are less toxic to cells, will be important tools for cell biology in the future. He added that coupling these techniques with adaptive optics will also further in vivo studies.
The number of students in the audience to hear Betzig and Hell give their presentations was testament to the importance of the Nobel Prize to inspire future generations of photonics scientists. Nobel Prize winners, Professor Serge Haroche and Professor Theodor Hänsch, also spoke during the Congress.
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