| University
of Toronto researchers have developed a new class of
hybrid materials that could one day move drug delivery
systems to the molecular level.
The paper published in the
Nov. 26 issue of Science outlines how a U of T research
team combined two classes of nanomaterials to create
an entirely new composite structure. This new porous
architecture may one day act as a nanoscale sieve,
enabling researchers to release drug molecules in
a slow and controlled way. "We hope one day to
create a film of this material and spread it on the
skin," says the paper's senior author University
Professor Geoffrey Ozin of the Department of Chemistry.
"By doing so, drugs can be diffused through the
skin, rather than injection, which would guarantee
a continuous flow of a drug molecule at a tunable
rate and concentration."
To create this new material,
Ozin and post-doctoral fellow Kai Landskron combine
dendrimers - a special class of highly organized nanosized
molecules - with a porous silica material. The functionalized
dendrimers are dissolved together with a template
in an aqueous solution. The solution causes the dendrimers
to react with water and then assemble around the template
into a new class of materials called periodic mesoporous
dendrisilicas (PMD). The PMD is a honeycomb-like structure
with pores measuring about 10 billionth of a metre
- and pore walls with internal pores of about one
billionth of a metre. This hierarchical construction
can enable drug molecules to slowly slip through the
various pores to target a particular disease.
"The problem with current
drug delivery systems like simple syringes is that
when you inject the drug, you often inject initially
too high a concentration to ensure it stays in the
system, which can be toxic," says Landskron,
the study's first author. "With this new type
of material, you could release the drug at an appropriate
rate and avoid these negative effects. You can fine
tune absorption and desorption and allow it to be
far more defined than ever before."
Landskron says the new hybrid
material may also have potential use in microelectronic
applications. As chip components are gradually shrinking
to tiny dimensions, new materials are needed to provide
packaging on the nanoscale level. "Currently,
the silica that insulates chips becomes less effective
as they become smaller," says Landskron. "The
new porous material could show greater insulating
abilities and are interesting as packaging material
in microelectronics."
According to Ozin, the next
step is to expand on the various ways to alter the
structure of PMDs, tailor their properties and develop
the basic science that will underpin the exploitation
of the PMDs in both drug delivery and microelectronic
applications.
Ozin is a Canada Research Chair
in Materials Chemistry. The research received funding
from the Natural Sciences and Engineering Research
Council of Canada.
CONTACT:
Geoffrey Ozin Kai Landskron
Department of Chemistry Department of Chemistry
416-978-2082 416-978-4735
gozin@chem.utoronto.ca klandskr@chem.utoronto.ca
Karen
Kelly
U of T Public Affairs
416-978-6974
k.kelly@utoronto.ca
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