Nanogallery
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TODAY OCTOBER 20, 2017

Selfassembly: New way to make superstructures at the molecular level

The principle of the bio-inspired selfassembly
Eugene Zubarev and his collaborators at Rice University developed a new bioinspired approach to selfassembly of nanoscale constructs involving gold and silver nanoparticles. The method is based on the Nature most famous chemical innovations the selfassembly of lipid membranes that surround every living cell.

The Figure illustrates the idea of this new principle of selfassembly.

E. R. Zubarev, J. Xu, A. Sayyad, J. D. Gibson "Amphiphilicity-Driven Organization of Nanoparticles into Discrete Assemblies." J. Am. Chem. Soc., 128 (2006): 15098-15099.

E. R. Zubarev, J. Xu, J. D. Gibson, A. Sayyad "From Small Building Blocks to Complex Molecular Architecture." Org. Lett., 8 (2006): 1367-1370.

11-27-06 Prof. Zubarev and his team at Rice University have discovered how to assemble gold and silver nanoparticle building blocks into larger structures based on a novel method that harkens back to one of Nature oldest known chemical innovations the self-assembly of lipid membranes that surround every living cell. Researchers believe the new method will allow them to create a wide variety of useful materials, including extra-potent cancer drugs and more efficient catalysts for the chemical industry. The method makes use of the hydrophobic effect, a biochemical phenomena that all living creatures use to create membranes, ultra-thin barriers of fatty acids that form a strong, yet dynamic, sack around the cell, sealing it from the outside world. Cell membranes are one example of a micelle, a strong bilayer covering that is made of two sheets of lipid-based amphiphiles, molecules that have a water-loving, or hydrophilic, end, and a water-hating, or hydrophobic, end. Like two pieces of cellophane tape being brought together, the hydrophobic sides of the amphiphilic sheets stick to one another, forming the bilayered micelle. Zubarev and colleagues synthesized V-shaped amphiphiles of polystyrene-b-poly(ethylene oxide) and attached two-nanometer diameter gold particles at the focal point of the V. Upon adding water and inducing micelle formation, the team found it could create tightly packed cylinders of gold nanoparticles measuring just 18 nanometers in diameter. All micelles form in three allowable shapes spheres, cylinders and sack-like vesicles. By varying the length of the polystyrene arm, the solvents used and the size of the gold particles Zubarev and colleagues were able to form spheres, vesicles and vary the diameter of their cylinders, some of which grew to well-over 1000 nanometers in length. The research was funded by the National Science Foundation and the Welch Foundation. Source/Credit: Rice University
See also images:
This electron microscope image clearly shows the tightly packed cylinders of gold nanoparticles.
The image is courtesy Eugene Zubarev/Rice University
This electron microscope image clearly shows the tightly packed cylinders of gold nanoparticles. The image is courtesy Eugene Zubarev/Rice University
The cylindrical superstructures are composed of silver nanoparticles with V-shaped amphiphilic arms. The short rod-like and spherical assemblies are made of gold nanoparticles with the same V-shaped amphiphilic arms.  The self-assembly occurs upon slow addition of water to solution of nanoparticles in organic solvent called tetrahydrofuran. The resulting mixture is then dialyzed against pure water in order to remove organic solvent and obtain a pure aqueous solution of the superstructures (they remain in water without any precipitation, just like micelles).
The cylindrical superstructures are composed of silver nanoparticles with V-shaped amphiphilic arms. The short rod-like and spherical assemblies are made of gold nanoparticles with the same V-shaped amphiphilic arms. The self-assembly occurs upon slow addition of water to solution of nanoparticles in organic solvent called tetrahydrofuran. The resulting mixture is then dialyzed against pure water in order to remove organic solvent and obtain a pure aqueous solution of the superstructures (they remain in water without any precipitation, just like micelles).

Related Links:
  • Eugene Zubarev page at Rice University
  • The substrate is then rinsed in a photoresist developer solution, in which all parts of the photoresist exposed to light are removed
    Nanowerk Nanotechnology Portal
    http://www.nanowerk.com

    Nanohedron
    http://www.nanohedron.com

    Biomolecules
    http://perso.curie.fr/Simon.Sc..


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