In a move akin to adding chemical weapons to a firebomb, researchers at
Duke University have devised a method for making a promising nanoscale cancer
treatment even more deadly to tumors.
The invention allows an extremely thin layer of hydrogels (think contact
lenses) to be deposited on the surface of nanoshells -- particles about a
hundred nanometers wide designed to absorb infrared light and generate heat.
When heated, these special hydrogels lose their water content and release any
molecules (such as drugs) trapped within.
By depositing the hydrogels on tumor-torching nanoshells and loading the
new coating with chemotherapeutic drugs, a formidable one-two punch is
formed.
The technique is described in a paper published in the journal ACS
Biomaterials Science & Engineering on July 13, 2015, and was highlighted as
an ACS Editor's Choice.
"The idea is to combine tumor-destroying heat therapy with localized drug
delivery, so that you can hopefully have the most effective treatment possible,"
said Jennifer West, the Fitzpatrick Family University Professor of Engineering
at Duke, who holds appointments in biomedical engineering, mechanical
engineering and materials science, cell biology, and chemistry. "And many
chemotherapeutic drugs have been shown to be more effective in heated tissue, so
there's a potential synergy between the two approaches."
The photothermal therapy is already in clinical trials for several types of
cancers being conducted by Nanospectra Biosciences, Inc., a company West
founded. The nanoshells are tuned to absorb near-infrared light, which passes
harmlessly through water and tissue. The nanoshells, however, quickly heat up
enough to destroy cells, but only where the light shines.
Besides being able to accurately target specific locations in the body with
the light, the treatment also hinges on the fact that nanoshells tend to
accumulate within a tumor due to leaky vasculature.
"But you have to keep their size under about 500 nanometers," said West.
"We had to come up with a new process to create a very thin polymer coating on
the surface of these nanoparticles to keep them under that threshold."
In the new study, West and doctoral student Laura Strong loaded the newly
coated nanoshells with a potent chemotherapeutic drug and delivered them to
tumor cells in a laboratory setting. The treatment worked as planned; the
nanoshells heated up and destroyed most of the tumor cells while releasing the
drugs, which cleaned up the survivors. Completely eradicating every cancerous
cell is extremely important, as the escape of even a single cell capable of
metastasizing could prove deadly down the road.
The next step for the new cancer treatment is tests in live animals. While
those experiments are in progress, human trials are still at least a couple
years away.
But the technology need not be limited to cancer therapy.
"The hydrogels can release drugs just above body temperature, so you could
potentially look at this for other drug-delivery applications where you don't
necessarily want to destroy the tissue," said West. "You could do a milder
warming and still trigger the drug release."
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