We encounter valves every day, whether in the water faucet, the carburetor in our car, or our bicycle tire tube. Valves are also present in the world of nanotechnology. A team of researchers headed by J. Fraser Stoddart and Jeffrey I. Zink at the University of California, Los Angeles, has now developed a new nanovalve.
In the journal Angewandte Chemie, the scientists reveal what is special about it: In contrast to prior versions, which only function in organic solvents, this valve operates in an aqueous environment and under physiological conditions—prerequisites for any application as a gate for nanoscopic drug-transport agents, which need to set their cargo free at the right place and time.
In order for pharmaceuticals to affect only the target diseased organ, suitable nanopackaging is required to bring the drug to the target area and release it only there. One example of a good nanoscopic packaging agent is a tiny sphere of porous silica. Its pores can be filled with the drug and closed with tiny controllable valves.
The scientists attached stem-shaped molecules onto the surface of the porous spheres and filled the pores with guest molecules. At neutral to acidic pH values, they stacked cucurbituril molecules onto these “stems”. Cucurbituril is a fat, ring-shaped molecule reminiscent of a pumpkin that has both ends hollowed out. The resulting supramolecular structure, which resembles a skewered pumpkin and is known to chemists as a pseudorotaxane, blocks the pores, so that the guest molecules cannot exit. The nanovalve is closed.
If the pH value is raised into the basic range, however, the interaction between the “pumpkins” and the “skewers” is weakened, and the pumpkins come off, opening the pores. Now the valves are open and the guest molecules can exit.
At this point the molecular details of the individual components still need to be tweaked. The goal: very small differences in pH values between healthy and diseased tissue should be sufficient to switch the valves and release the drug only in diseased cells.
Author: Jeffrey I. Zink, University of California, Los Angeles (USA), http://www.chem.ucla.edu/dept/Faculty/jzink/
Title: pH-Responsive Supramolecular Nanovalves Based on Cucurbituril Pseudorotaxanes
Angewandte Chemie International Edition 2008, 47, No. 12, 2222–2226, doi: 10.1002/anie.200705211
O2 stable hydrogenases for applications
23.07.2018 | Max-Planck-Institut für Chemische Energiekonversion
Scientists uncover the role of a protein in production & survival of myelin-forming cells
19.07.2018 | Advanced Science Research Center, GC/CUNY
A new manufacturing technique uses a process similar to newspaper printing to form smoother and more flexible metals for making ultrafast electronic devices.
The low-cost process, developed by Purdue University researchers, combines tools already used in industry for manufacturing metals on a large scale, but uses...
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....
13.07.2018 | Event News
12.07.2018 | Event News
03.07.2018 | Event News
23.07.2018 | Science Education
23.07.2018 | Health and Medicine
23.07.2018 | Life Sciences