ROCKET TO THE STOMACH
The lab of Joseph Wang, a nanoengineering
professor at UC San Diego’s Jacobs School of
Engineering, is the first stop on UC San Diego’s
own fantastic voyage. There, you’ll find a team
creating tube-shaped micromotors—smaller
than the width of a human hair—that could one
day be used to efficiently deliver drugs to specific
locations in the body, or even perform surgeries
and conduct biopsies on hard-to-reach tumors.
Wang recently teamed up with Liangfang Zhang,
a nanoengineering professor affiliated with the
cross-disciplinary Institute of Engineering in
Medicine, to demonstrate how micromotors
could be deployed inside a mouse’s stomach
and deliver cargo to the stomach wall. “This is
the first example of loading and releasing a
cargo in vivo,” says Wang. “We thought it was
the logical extension of the work we have done,
to see if these motors might be able to swim in
Not only are they able to swim in stomach
acid, the acid is a major factor in their ability to
swim at all. Made primarily of zinc, these tubular
micromotors react with stomach acid to generate
a stream of hydrogen bubbles that propel the
motors like miniature rockets. This propulsive
burst allows the motors to swim around and
lodge themselves and their cargo firmly in
the stomach wall. As a bonus feature, the zinc
micromotors are biodegradable—they gradually
dissolve in stomach acid, disappearing within a
few days with no toxic traces left behind.
As part of their experiment, Wang, Zhang and
their cohorts tested the ability of micromotors
to deliver a cargo of gold nanoparticles to
the stomach wall of mice. The mice ingested
tiny drops of solution containing hundreds of
these gold-loaded micromotors, which became
active as soon as they hit the stomach acid and
propelled themselves toward the stomach wall.
Remarkably, the researchers found that more
than three times as many gold nanoparticles
ended up in the stomachs of mice when delivered
by the micromotors, compared to when the gold
nanoparticles alone were ingested normally.
The experiment shows the promise of
micromotors to safely and efficiently deliver cargo
in living animals, a prospect that could one day
revolutionize drug delivery. Yet there is much
to be explored before that day comes—elements
like navigation capabilities and more precise
targeting will be crucial.
In 1966, when UC San Diego was little more than a patchwork of Quonset huts and
former military barracks, theaters across America premiered the science fiction movie
Fantastic Voyage. In it, a submarine and its crew are shrunk to microscopic size and
injected into the body of a scientist suffering from an inoperable blood clot in his brain.
The mission: repair the blood clot and save his life.
The concept was truly fantastic for the time; so much so that any researcher peering into
a microscope at then-UC La Jolla may have justly relegated it to science fiction forever.
How could they have known that decades later, researchers would strive to master that
fantastic frontier—to save not only one life, but impact the lives of millions?
A DRUG IN CANCER’S CLOTHING BY SUSAN BROWN
The key to destroying cancer cells may be in the very enzymes
that make them dangerous. Known as matrix metalloprotein-ases (MMP), these enzymes chew through membranes and let
cancer cells colonize other regions of the body, often with deadly
consequences. UC San Diego chemists have recently designed
nanoparticles that release drugs strictly in the presence of these
enzymes, focusing the effects of medicine where it’s
A team led by Nathan Gianneschi, professor of chemistry and
biochemistry, has taken tiny spheres of anti-cancer drugs, or
nanospheres, and coated them with a protective shell made
of peptides—the very membrane proteins that MMPs love to
chew through. Yet when the cancer cells tear up the shell and
release the drug, the shredded shell forms a ragged mesh that
entangles the drug particles, keeping them near the tumor.