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Common
Ingredient in Big Macs and Sodas Can Stabilize Gold Nanoparticles
for Medical Use, Researchers Find
Gold
nanoparticles could be used to detect and treat cancer and other
diseases
COLUMBIA, Mo. - The future of cancer
detection and treatment may be in gold nanoparticles - tiny
pieces of gold so small they cannot be seen by the naked eye. The
potential of gold nanoparticles has been hindered by the
difficulty of making them in a stable, nontoxic form that can be
injected into a patient. New research at the University of
Missouri-Columbia has found that a plant extract can be used to
overcome this problem, creating a new type of gold nanoparticle
that is stable and nontoxic and can be administered orally or
injected.
Because gold nanoparticles
have a high surface reactivity and biocompatible properties, they
can be used for in vivo (inside the bod)) molecular imaging and
therapeutic applications, including cancer detection and therapy.
The promise of nanomedicine comes from the high surface area and
size relationships of nanoparticles to cells, making it possible
to target individual cells for diagnostic imaging or therapy.
Gold nanoparticles could function as in vivo sensors, photoactive
agents for optical imaging, drug carriers, contrast enhancers in
computer tomography and X-ray absorbers in cancer therapy.
Despite their promise, however, scientists have been plagued with
problems making nontoxic gold nanoparticle constructs.
Kattesh
Katti, professor of radiology and physics in MU's School of
Medicine and College of Arts and Science, and director of the
University of Missouri Cancer Nanotechnology Platform, worked
with other MU scientists in the fields of physics, radiology,
chemistry and veterinary medicine. The team tested plant extracts
for their ability as nontoxic vehicles to stabilize and deliver
nanoparticles for in vivo nanomedicinal applications. The
researchers became interested in gum arabic, a substance taken
from species of the acacia tree, because it is already used to
stabilize everyday foods such as yogurt, Big Macs and soda. Gum
arabic has unique structural features, including a highly
branched polysaccharide structure consisting of a complex mixture
of potassium, calcium and magnesium salts derived from arabic
acid. The scientists found that gum arabic could be used to
absorb and assimilate metals and create a "coating"
that makes gold nanoparticles stable and nontoxic.
Katti
and Raghuraman Kannan, assistant professor of radiology, have
been collaborating on the development of biocompatible gold and
silver nanoparticles for medical applications.
"We
found that gum arabic can effectively 'lock' gold nanoparticles
to produce nontoxic, nanoparticulate constructs that can be used
for potential applications in nanomedicine," Katti said. "We
have developed a new class of hybrid gold nanoparticles that are
stable and can be administered either orally or through
intravenous injection within the biological system."
This
finding could lead to the development of readily injectable gold
nanoparticles that are nontoxic and stable. Mansoor Amiji,
professor of pharmaceutical sciences in the Bouve College of
Health
Sciences' School of Pharmacy and co-director of the
Nanomedicine Education and Research Consortium at Northeastern
University in Boston, said this represents a major scientific
discovery that will initiate a new generation of biocompatible
gold nanoparticles.
"The excellent in vivo stability
profiles of such gold nanoconstructs will open up new pathways
for the intratumoral delivery of gold nanoparticles in diagnostic
imaging and therapeutic applications for cancer," Amiji
said.
The new generation of trimeric amino acids peptides
discovered by Katti in 1999 (referred to by Amijii as 'Katti
Peptides') have provided a solid chemical platform and have
become sources of a number of other discoveries. Their
applications in the development of drugs for Wilscons' disease;
their utility for the generation of a wide spectrum of metallic
nanoparticles, including gold and silver; and as amphiphilic
building blocks in a variety of drug designs were demonstrated by
Katti, in collaboration with Kannan and MU's Stan Casteel.
A
paper describing the team's recent findings, "Gum arabic as
a Phytochemical Construct for the Stabilization of Gold
Nanoparticles: In Vivo Pharmacokinetics and X-ray
Contrast-Imaging Studies," was recently published in the
February edition of the journal Small. Katti's collaborators on
this paper include Casteel, Kannan, David Robertson, Evan Boote,
Genevieve M. Fent, Kavita Katti, Vijaya Kattumauri and Meera
Chandrasekhar.
This work has been supported with a grant
from the National Institutes of Health/National Cancer Institute
under the Cancer Nanotechnology Platform program.
Source
/ Credit: University of Missouri-Columbia
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