Transmission electron microscopy (TEM) image of an ultrabright fluorescent mesoporous silica nanoparticle (image colored artificially to match the actual color of the dye in the particles). |
Clarkson
University Physics Professor Igor Sokolov and his team have discovered a
method of making the brightest-ever synthesized fluorescent silica
nanoparticles.
The
scientists reported on the first successful approach to synthesizing
ultrabright fluorescent mesoporous silica nanoparticles this fall in the
leading interdisciplinary scientific journal Small.
These
nanoparticles have potential applications in medicine, biology,
material science, and environmental protection, among many other uses.
Fluorescent
materials are already used in many of these applications. However,
having much brighter labeling particles will allow much finer detection
of environmental pollutants, signals in biosensors and even the
detection of explosives.
In
fluorescence, an initial ignition light energizes molecules, and then
the molecules reemit the light with a different color. This phenomenon
can be used in many different applications because it is easily
detectable, using optical filters to remove the ignition light, leaving
only the particles’ light visible.
“The
particles should have a significant impact in the biomedical area,”
says Sokolov. “For example, you can create particles of different
colors, which can be made to stick to particular biological molecules
inside cells. Then you can see and trace those molecules easily with
existing fluorescent microscopes. This fluorescent labeling helps to
identify diseased cells and may show what is causing the disease. The
particles are much more stable against photo-beaching than typical
fluorescent dye. This means that one can trace the particles for a very
long time.”
Sokolov’s
process physically entraps a large number of organic fluorescent
molecules inside nanoporous silica particles, which can be 20 to 50
nanometers in diameter, while preventing the molecules from leaking.
As
an example of their brightness, the fluorescence of 40-nanometer
particles is 34 times brighter than the brightest water-dispersible
(25-30 nanometer) quantum dots and seem to be the brightest
nanoparticles created so far.
In
2007, Sokolov and his team discovered a method of making the brightest
ever synthesized fluorescent silica micro (non-nano) particles. Various
attempts to decrease the size of the particles down to the nanoscale led
to the particles that were bright but not ultrabright. The problem was
in the dye leakage. It took the group several years to finally
synthesize the ultrabright nanoparticles.
Sokolov
and postdoctoral fellow Eun-Bum Cho (now an assistant professor at
Seoul National University of Science and Technology) and Ph.D. student
Dmytro Volkov developed the process, which gives the desired
nanoparticles. The group, which now includes postdoctoral fellow Shajesh
Palantavida, is currently looking at the development of the particles
suitable for biomedical labeling.
The
research was partially supported by the National Science Foundation and
the U.S. Army Research Laboratory’s Army Research Office. It was
performed in Clarkson’s Nanoengineering and Biotechnology Laboratories
Center (NABLAB), a unit led by Sokolov and established to promote
cross-disciplinary collaborations within the University.
NABLAB
comprises more than a dozen faculty members who apply the expertise of
Clarkson scholars to cancer cell research, fine particles for bio and
medical applications, synthesis of smart materials, advancement
biosensors, and more.
