American researchers have developed a probe for marking biomolecules that begins to fluoresce only when it is “switched on” by binding. As reported in the journal Angewandte Chemie, the reaction takes place very quickly and the difference in brightness between the “on” and “off” states is two orders of magnitude bigger than for conventional activatable probes.
Marking biomolecules in living cells with fluorescent probes is a well-established technique. New research possibilities open up when these probes are combined with bioorthogonal reactions. Such reactions can occur inside a living system without disrupting normal biochemical processes.
This makes it possible to generate “turn-on” probes: a bioorthogonal reaction binding partner is bound to the biomolecule of interest (without affecting it) and acts as an anchoring site for the fluorescent probe. The probe is devised so that its fluorescence is significantly increased when it binds to the anchoring site. Because the probes not bound to the target fluoresce far less, background fluorescence is reduced. This eliminates the need for complex washing procedures that delay observation of the cells.
For all of this to work, the probe system must work without a toxic catalyst, react quickly to allow for time-resolved observation of biological processes, and fluoresce very strongly after being “turned on” to maximize the signal–strength relative to the background. It has not previously been possible to meet all of these requirements in one system.
A team led by Ralph Weissleder at Massachusetts General Hospital and Harvard University has now developed a system that fits the bill: an unusually bright, fast reacting, biocompatible probe system with a large difference between the switched on and switched off states.
The new probe consists of two components: The first is a fluorescent dye called BODIPY (boron dipyrromethene), a three-ring system with a subunit made of one boron, two nitrogen, and two fluorine atoms. The second component is a tetrazine molecule, a six-membered ring containing four nitrogen and two carbon atoms. Tetrazine quenches the fluorescence of BODIPY, which passes incoming energy off to the tetrazine component without radiation instead of fluorescing.
The reaction destroys the probe’s tetrazine group, turning off the quenching of the fluorescence and allowing the BODIPY molecule to glow an intense green. The researchers recorded fluorescence over a thousand times stronger than that of the probe in the “off” state. This is two orders of magnitude stronger than all previously described turn-on probes.
The success of this system is due to the particularly strong fluorescence quenching made possible by the special electronic constellation and spatial arrangement of the BODIPY and tetrazine components relative to each other.About the Author
Ralph Weissleder | Angewandte Chemie
Repairing damaged hearts with self-healing heart cells
22.08.2017 | National University Health System
Biochemical 'fingerprints' reveal diabetes progression
22.08.2017 | Umea University
Whether you call it effervescent, fizzy, or sparkling, carbonated water is making a comeback as a beverage. Aside from quenching thirst, researchers at the University of Illinois at Urbana-Champaign have discovered a new use for these "bubbly" concoctions that will have major impact on the manufacturer of the world's thinnest, flattest, and one most useful materials -- graphene.
As graphene's popularity grows as an advanced "wonder" material, the speed and quality at which it can be manufactured will be paramount. With that in mind,...
Physicists at the University of Bonn have managed to create optical hollows and more complex patterns into which the light of a Bose-Einstein condensate flows. The creation of such highly low-loss structures for light is a prerequisite for complex light circuits, such as for quantum information processing for a new generation of computers. The researchers are now presenting their results in the journal Nature Photonics.
Light particles (photons) occur as tiny, indivisible portions. Many thousands of these light portions can be merged to form a single super-photon if they are...
For the first time, scientists have shown that circular RNA is linked to brain function. When a RNA molecule called Cdr1as was deleted from the genome of mice, the animals had problems filtering out unnecessary information – like patients suffering from neuropsychiatric disorders.
While hundreds of circular RNAs (circRNAs) are abundant in mammalian brains, one big question has remained unanswered: What are they actually good for? In the...
An experimental small satellite has successfully collected and delivered data on a key measurement for predicting changes in Earth's climate.
The Radiometer Assessment using Vertically Aligned Nanotubes (RAVAN) CubeSat was launched into low-Earth orbit on Nov. 11, 2016, in order to test new...
A study led by scientists of the Max Planck Institute for the Structure and Dynamics of Matter (MPSD) at the Center for Free-Electron Laser Science in Hamburg presents evidence of the coexistence of superconductivity and “charge-density-waves” in compounds of the poorly-studied family of bismuthates. This observation opens up new perspectives for a deeper understanding of the phenomenon of high-temperature superconductivity, a topic which is at the core of condensed matter research since more than 30 years. The paper by Nicoletti et al has been published in the PNAS.
Since the beginning of the 20th century, superconductivity had been observed in some metals at temperatures only a few degrees above the absolute zero (minus...
16.08.2017 | Event News
04.08.2017 | Event News
26.07.2017 | Event News
22.08.2017 | Health and Medicine
22.08.2017 | Materials Sciences
22.08.2017 | Life Sciences