Organic nanotubes could make rapid strides as functional nanomaterials in a new approach to nanoelectronics and biomedicine, as they can be made of easily varied and modified building blocks.
Researchers led by Chulhee Kim at the Inha University in South Korea have recently developed nanotubes made of dendrons and cyclodextrins. As reported in the journal Angewandte Chemie, they have now successfully functionalized the surfaces of the tubes so that, among other things, they can be used to make biosensors for the detection of a specific protein.
Dendron is the Greek word for tree. Dendrons are tree-shaped branched molecules. Kim and Chiyoung Park selected a molecular “tree” with four long hydrocarbon chains as “branches”. At the end of the “trunk” they attached a pyrene group, a system made of four aromatic carbon rings. In solution, these dendrons come together “branch to branch” to form vesicles, or tiny bubbles. If the researchers add cyclodextrins, which are ring-shaped closed chains of glucose rings, each of these settles around a pyrene group like a cuff. This makes it more favorable for the dendrons to group themselves into long nanoscopic tubes whose surfaces are coated with the cyclodextrin “cuffs”.
What makes this concept into a truly universal construction set is that the cyclodextrins can easily be equipped with a large variety of functional groups, which then dangle out into the solution from the surfaces of the tubes. The team was thus able to attach special groups that like to bind gold nanoparticles. Nanotubes that are densely covered in metal particles could have interesting applications in nanoelectronics.
The pyrene groups on the nanotubes have another special advantage: they fluoresce. This property allows them to be used in the design of biosensors. To demonstrate this concept, the researchers constructed a specific test for the protein avidin. They equipped the surfaces of the nanotubes with biotin, a biomolecule that specifically binds the proteins avidin and streptavidin. If streptavidin bound to gold nanoparticles is added, these bind to the nanotubes by way of the biotin anchors. This brings the gold particles into the vicinity of the pyrene groups, which causes them to interact electronically, “switching off” the fluorescence. If the protein avidin and the gold-bound streptavidin are added, biotin anchors on the surface of the tube preferentially bind avidin. Pyrene groups in the vicinity of avidin fluoresce. The fluorescence quencher gold-strepavidin can only bind to the binding sites not occupied by avidin. The intensity of the fluorescence therefore depends on the avidin concentration.
Author: Chulhee Kim, Inha University, Incheon (South Korea), http://webhome.inha.ac.kr/fplab/Professor.htm
Title: Tunable Fluorescent Dendron-Cyclodextrin Nanotubes for Hybridization with Metal Nanoparticles and their Biosensory Function
Angewandte Chemie International Edition 2008, 47, No. 51, doi: 10.1002/anie.200804087
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