Subject: [permaculture] Nano science and nano microscopy
Date: Wed, 20 Feb 2008 08:21:08 -0500
Scientists Scan Striking Nanoscale Images
By Emmet Cole Write to the Author
02.15.08 | 12:00 AM
For the first time, late last year, a team of British scientists filmed the nanoscale interaction of an attacking virus
with an enzyme and a DNA strand in real time.
This was the latest breakthrough in the advancement of scanning probe microscopes -- the family of nonoptical
microscopes researchers use to create striking images through raster scans of individual atoms.
The granddaddy of them all is the scanning tunneling microscope, a 1986 invention that won its creators the Nobel Prize.
STMs pass an electrical probe over a substance, allowing scientists to visualize regions of high electron density and
infer the position of individual atoms and molecules.
To mark the 25th anniversary of the development of STMs, an international contest -- SPMage07 -- showcasing the best STM
images was founded.
Cyanobacteria
This image of cyanobacteria (more commonly known as blue-green algae) was taken as part of a series of experiments
designed to help scientists understand how the structure of the algae's cell walls helps it move.
Simon Connell and David Adams at the university's School of Physics are applying the latest AFM techniques to biological
systems like cell division, chemotaxis and symbiosis.
AFMs operate at incredibly fine levels of sensitivity, Connellsays , adding that one nanoNewton is "equivalent to the
attractive force solely due to gravitation between two players on a tennis court." Ace!
The leaves of several plants, including the lotus plant, show self-cleaning
properties.
The so-called "lotus effect" that results means that every rain shower washes away dust particles that would otherwise
reduce the plant's ability to photosynthesize and leave it feeling a bit untidy and depressed.
This 2 micron x 2 micron AFM image shows one man-made attempt to mimic the dust-busting properties of the lotus -- a
carpetlike assembly of nanowires, created by a chemical vapor deposition process. When water droplets hit the
superhydrophobic nanowires, they quickly roll off, taking those pesky dust particles with them.
Oliver Bumchen/Saarland University, Germany and SPMage07
This E. coli bacterium displays well-preserved flagella that are just 30
nanometers long.
An atomic-force microscope was used to capture the image. Unlike scanning tunneling microscopes, the tip of an AFM comes
into direct contact with the surface of the sample. The force between the tip (known as "the bend") is calculated by
measuring the force exerted on a tiny cantilever.
AFMs are so sensitive that they can detect forces as small as a few
picoNewton (one trillionth of a Newton).
An electrostatic force microscope was used to create this tapewormlike image of the charge emission from a carbon
nanotube just 18 nanometers in diameter. EFMs leverage classical electrostatic forces to create images that could not be
taken with STMs, Mariusz Zdrojeck says.
"EFM is a very easy method [by which] to observe electrostatic behavior of any (not only nanotubes) object in the
nanoworld," says Zdrojek, who hopes that his research will make new electronic devices possible.
The bright halo is created by charges emitted from the nanotube cap, while
the discharged nanotube appears dark.
Mariusz Zdrojek/Warsaw University of Technology, Poland and SPMage07
STMs are used for more than just passively viewing individual atoms. They can be used to manipulate individual atoms by
picking them up (or pushing them from side to side) using the tip of the microscope, some fine calibration and a steady
hand.
"STMs are the first and best tool for manipulating atoms one at a time," says Jody (Seung Yun) Yang, a University of
Toronto chemist who took this STM image to demonstrate "a new method for imprinting on the molecular scale."
The result? An up-close and personal look at 12 bromine atoms, arranged in a
circle through molecular self-assembly.
Yang is currently working on the development of a nanoscale printing press.
Jody (Seung Yun) Yang/University of Toronto and SPMage07
These bagel-like blood cells won second place in SPMage07, and were taken to assist research into the effects of
antibiotic peptides on cell membranes.
This image shows the surface of human red blood cells after treatment with phyllomelittin, an antibiotic isolated from
the skin of the monkey frog.