Originally Published EMDM November/December 2001
TECHNOLOGY NEWS
Materials
Biomimetic Silicones Take a Cue from Nature
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Silicone
materials that mimic the body’s renewal of epithelial cells hold
promise as a platform for drug delivery.
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A team of biomaterials
and drug-delivery scientists at the School of Pharmacy, Queen’s University
Belfast (QUB; Belfast, Northern Ireland) has developed a patented technology
for the production of biomimetic silicone materials that can imitate the body’s
natural defence mechanisms.
With a coefficient of friction approaching zero, the silicone materials are highly lubricious. This property should enable their easy insertion and removal without pain or tissue trauma, says team member Sean Gorman, who is chair of the pharmaceutical microbiology department at QUB and heads up the school’s medical devices group.
Another innovative
feature of the silicones is that they are self-cleaning. Like the body’s
epithelial tissues, the materials can fight adhesion through the shedding and
renewal of their surfaces. The silicones, which can be created with varying
levels of hardness, can be processed using conventional methods and can withstand
gamma irradiation.
The technology
used to produce the materials relies on the use of higher-molecular-weight polysilanes
as cross-linking agents for silicones. Gorman describes the chemical mechanism
underlying the materials’ increased lubricity using an analogy from nature.
“It’s like what might happen if you tried to hold a fish in your hand.
It’s a slippery surface that has been designed by evolution to prevent
adhesion,” he says. “We see our materials as offering this same characteristic
by taking a lesson from evolution,” he adds.
In addition, the
enhanced lubricity of the silicones holds promise as a platform for drug delivery.
Gorman notes that the materials can be tailored to deliver an active agent over
a specific course of time, from days to months.
Gorman, along with
two professorial colleagues, has formed a company, Xiomateria Ltd., to develop
the materials. The enterprise, which is based at QUB, will not manufacture products
itself, but is seeking to license its technology to third parties for codevelopment
of specific clinical and nonclinical applications. The company is currently
in negotiations with a US manufacturer.
According to Gorman,
a further advantage of the new materials is that they do not present any substantive
alterations from the RTV silicones currently used in medical devices. “They
are made in the same manner, and there is no downside as far as cost is concerned,”
he says. Furthermore, he notes, they are “every bit as biocompatible as
their parent substance.”
Looking beyond
the new silicones, Gorman makes both a technical and a philosophical case for
a biomimetic approach to materials engineering. “Materials should mimic
nature,” he says. “It is arrogant for us as biomaterial engineers
to assume that we can provide a replacement for a urethra or a vein by manufacturing
a device from a single material.” He adds that his team’s approach
has been “to combine the structural engineering in current device technology
with new materials that offer the benefits of evolution.”
Benjamin Lichtman
Copyright ©2001
European Medical Device Manufacturer
