Far-field optical nanoscopy methods, especially STED (stimulated emission depletion), pose very strict and, at times, contradictory requirements on the utilized fluorescent markers. Photostable fluorescent dyes that absorb in the red optical region are indispensable as labels for various micro- and nanoscopic studies (e.g., with commercially available STED microscopes).
Despite many attempts to design novel and improved red-emitting dyes, the number of compounds that perform satisfactorily in fluorescence-based microscopy is still limited. Because of this, a great deal of research is being carried out by a large multidisciplinary team headed by Prof. Stefan W. Hell at the Department of NanoBiophotonics in Max Planck Institute for Biophysical Chemistry (Göttingen). In their recent paper published in the European Journal of Organic Chemistry the team describes a general synthetic route to new improved carbopyronine dyes and their performance in confocal and STED microscopy.
The new dyes have large fluorescence quantum yields, high water solubility, and the required positions of the absorption and emission bands in the red. The chemists came up with a synthetically feasible structural scaffold with functional groups that can be varied in the final steps of the synthesis or even in the resulting fluorescent dye to fit a given task. According to Dr. Kirill Kolmakov, who performed the synthesis, his “table book” contained a dissertation and articles and patents by Prof. K. Drexhage and co-workers, whose contribution to the synthesis of carbopyronines is fundamental. However, the synthetic approach presented in their EurJOC article is by far more flexible and improved. In particular, it starts from one simple precursor and utilizes a minimum amount of protecting groups. The key feature of the general strategy described therein is the interplay of certain protecting groups. Protecting groups will take an even more important part in the design and synthesis of caged carbopyronines and rhodamines that emit in the far-red spectral region. Besides the interesting chemistry, the team demonstrates that the performance of a dye in confocal microscopy and under STED conditions does not necessarily correlate. Dr. Kolmakov thus emphasizes that for their future research work, they will have to reconsider some of their old views on the “ideal” STED dye. All these make the primary article a good example of teamwork that is strategically sound, brilliantly planned, and perfectly delivered.
Author: Vladimir N. Belov, Max Planck Institute for Biophysical Chemistry, Göttingen (Germany),
Title: A Versatile Route to Red-Emitting Carbopyronine Dyes for Optical Microscopy and Nanoscopy
European Journal of Organic Chemistry , 2010, No. 19, 3593–3610, Permalink to the article: http://dx.doi.org/10.1002/ejoc.201000343
Rainbow colors reveal cell history: Uncovering β-cell heterogeneity
22.09.2017 | DFG-Forschungszentrum für Regenerative Therapien TU Dresden
The pyrenoid is a carbon-fixing liquid droplet
22.09.2017 | Max-Planck-Institut für Biochemie
Plants and algae use the enzyme Rubisco to fix carbon dioxide, removing it from the atmosphere and converting it into biomass. Algae have figured out a way to increase the efficiency of carbon fixation. They gather most of their Rubisco into a ball-shaped microcompartment called the pyrenoid, which they flood with a high local concentration of carbon dioxide. A team of scientists at Princeton University, the Carnegie Institution for Science, Stanford University and the Max Plank Institute of Biochemistry have unravelled the mysteries of how the pyrenoid is assembled. These insights can help to engineer crops that remove more carbon dioxide from the atmosphere while producing more food.
A warming planet
Our brains house extremely complex neuronal circuits, whose detailed structures are still largely unknown. This is especially true for the so-called cerebral cortex of mammals, where among other things vision, thoughts or spatial orientation are being computed. Here the rules by which nerve cells are connected to each other are only partly understood. A team of scientists around Moritz Helmstaedter at the Frankfiurt Max Planck Institute for Brain Research and Helene Schmidt (Humboldt University in Berlin) have now discovered a surprisingly precise nerve cell connectivity pattern in the part of the cerebral cortex that is responsible for orienting the individual animal or human in space.
The researchers report online in Nature (Schmidt et al., 2017. Axonal synapse sorting in medial entorhinal cortex, DOI: 10.1038/nature24005) that synapses in...
Whispering gallery mode (WGM) resonators are used to make tiny micro-lasers, sensors, switches, routers and other devices. These tiny structures rely on a...
Using ultrafast flashes of laser and x-ray radiation, scientists at the Max Planck Institute of Quantum Optics (Garching, Germany) took snapshots of the briefest electron motion inside a solid material to date. The electron motion lasted only 750 billionths of the billionth of a second before it fainted, setting a new record of human capability to capture ultrafast processes inside solids!
When x-rays shine onto solid materials or large molecules, an electron is pushed away from its original place near the nucleus of the atom, leaving a hole...
For the first time, physicists have successfully imaged spiral magnetic ordering in a multiferroic material. These materials are considered highly promising candidates for future data storage media. The researchers were able to prove their findings using unique quantum sensors that were developed at Basel University and that can analyze electromagnetic fields on the nanometer scale. The results – obtained by scientists from the University of Basel’s Department of Physics, the Swiss Nanoscience Institute, the University of Montpellier and several laboratories from University Paris-Saclay – were recently published in the journal Nature.
Multiferroics are materials that simultaneously react to electric and magnetic fields. These two properties are rarely found together, and their combined...
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