nanotehnoloogia, nanoteknologia, nanotechnologija, nanotehnologijas, nanoteknologija,
nanotechnologii, nanotecnologia, nanotehnologijo, nanoteknik
Nano Geneeskunde...Nano Medicína
Provide Crucial Clue to New Nanofiber Fabrication
Snapshot of initial
polymer fiber (15 min exposure to monomer and high
humidity) growth on fingerprint at 30 C and relative
(a) Low magnification view (b) Close-up view of
the same (inset showing the top view of fiber).
Reproduced by permission of The Royal Society
are usually used to identify people but, this time,
they gave Penn State chemical engineers the crucial
clue needed to discover an easy, versatile new method
for making nanofibers that have potential uses in
advanced filtration as well as wound care, drug delivery,
bioassays and other medical applications.
The new technique is based on the way forensic scientists develop fingerprints
from a crime scene and is easier and more versatile than either of the current
methods, templates or electrospinning, used commercially to make nanofibers.
Scanning electron microscope pictures of
nanofibers of poly ethyl cyanoacrylate grown on
fingerprint ridges at 30 C and relative humidity >95%
over a period of 16h (a) Low magnification view
(b) Close-up view of the ridge pattern. (c) Close-up
view of the nanofibers (d) Magnified view of a
single fiber. Reproduced by permission of The Royal
Society of Chemistry
first nanofibers generated by the technique are made
from the basic ingredient of Super Glue, cyanoacrylate,
which is a biologically-compatible material already
used in liquid sutures, spheres for drug delivery
and in experimental cancer treatment. However, the
researchers say that other materials, like cyanoacrylate,
that form solid polymers when nudged by a catalyst
could potentially also be used in the process.
Dr. Henry C. Foley, professor of chemical engineering who directed the project,
says, "The new technique is so versatile that it allows us not only to make
nano-scale fibers but also nano-sized flat sheets, spheres and even wrinkled
sheets that look tortellini-like."
The researchers can also generate patterned surfaces and say that the process
could conceivably be used in an ink jet printer.
The research is detailed in a paper, "Facile Catalytic Growth of Cyanoacrylate
Nanofibers," published online today (Jan. 26) in the British journal, The Royal
Society of Chemistry, Chemical Communications. The authors are Pratik J. Mankidy,
doctoral candidate in chemical engineering; Ramakrishnan Rajagopalan, research
associate at Penn State's Materials Research Laboratory, and Foley, who is
also associate vice president for research at the University. The journal is
available here .
Foley explains that forensic scientists develop latent fingerprints via a process
known as cyanoacrylate fuming. Fingerprints left on a surface are exposed to
fumes of cyanoacrylate, which form a white polymer residue that makes the ridges
of the fingerprint visible.
One of the researchers, Pratik Mankidy, had accidentally left his fingerprints
on a piece of research equipment that had been secured with Super Glue and
nanofibers appeared. Putting two and two together, the researchers set out
to discover what constituents of fingerprints trigger the cyanoacrylate polymerization
on the ridges of fingerprints.
They made synthetic fingerprints from a mixture of a known polymer initiator,
common table salt in water, and a non-initiator, linoleic acid, found on fingers.
Then they exposed the fake prints to cyanoacrylate fuming. Sure enough, they
got nanofibers similar to the ones Mankidy's fingerprints had generated accidentally.
They also fumed cyanoacrylate on single initiators and found that sodium hydroxide,
potassium hydroxide and potassium acetate produced tortellini-like films of
the polymer. When ammonium hydroxide was fumed with cyanoacrylate, it produced
The researchers note that the role played by the presence of the non-initiating
components in the fingerprint mixture is not completely understood. They are
continuing their experiments to understand the process more completely.
A majority of the fibers produced by the new process have diameters in the
200-250 nanometer range and are hundreds of microns long. Typically, nanofibers
that are currently commercially available are in this same range.
Foley notes, "Our findings open up a whole new world of opportunity for control
of nanoscale structures through chemistry via catalysis."
The research was supported by a grant from the National Science Foundation.
A'ndrea Elyse Messer
Science & Research Information Officer
story has been adapted from a news release
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