YSM Issue 86.1

FEATURE
TECHNOLOGY
Microbots: Using Nanotechnology in Medicine
by Jenna Kainic
The human body houses a complex of twisted pathways, labyrinths
of tunnels, unimaginably small. The biological systems responsible for
the flow of the blood, oxygen, and electrical impulses that sustain us
are intricate and delicately coordinated. And so, when these systems go
wrong, when our bodies are vulnerable to cancers and diseases, it seems
at first ideal to have medicine that can perform on a scale as small and
complex as the circuitry on which it acts. Rather than exposing the whole
body to toxic chemotherapy drugs, imagine
cancer treatments that could deliver drugs
directly to malignant cells. Consider swallowing
a device that could travel through
your body, looking for signs of irritation
and illness.
Such a world seems surreal and evokes
images of science fiction stories and children’s
books. However, the possibility of
having tiny robots navigate the smallest
passages of the human body is not far from
being a reality. In fact, important steps have
already been taken towards the creation and
use of such nanotechnologies. When perfected,
these microbots will enable doctors
to explore and mend patients’ ailments with
greater insight and precision.
First Steps
The first step toward using nanotechnology
in medicine occurred in 2001, when
Given Imaging introduced the PillCam.
The PillCam is a capsule containing a light
and camera that a patient swallows. Images
beamed wirelessly from the capsule can be
analyzed and used for diagnostic purposes,
The PillCam is about the size of a large pill
and can be swallowed. Courtesy of afutured.
com.
thus replacing procedures like the traditional endoscopy, in which a flexible
tube containing a flashlight and camera is inserted into the digestive
tract. The PillCam, at about the size of a normal pill, is ideal for use in
the passageways of the gastrointestinal system since it can be swallowed.
However, the digestive system is comprised of relatively large pathways
compared to those of the arteries and capillaries, which can be as small
as a few micrometers in diameter. The PillCam is thus still too large to
travel through the entire circulatory system. Additionally, the device lacks
a means of navigating itself through the body; it merely travels passively
along the natural course of the digestive system.
Thus, in order to explore passageways like those in the circulatory
system, scientists needed to find a means
of creating a smaller device that would be
able to propel itself against the flow of the
bloodstream. The difficulty of this task was
largely in the size of the technology needed.
Any traditionally built battery-powered motor
would be far too large to fit through passages
only micrometers thick.
Drug-Delivering Devices
Scientists have managed to overcome this
obstacle by using magnets instead of motors
to propel the devices. Dr. Sylvain Martel, the
founder and director of the NanoRobotics
Laboratory at the École Polytechnique de
Montréal, and his team have developed microcarriers
that are able to pass through the larger
arteries. These microcarriers are navigated by
the magnetic coils of an MRI machine and have
successfully delivered drugs to rabbits’ livers.
Similarly, a team in Dresden has created
microtubes made of titanium, iron, and platinum.
According to a paper written by this team
on their research, these rolled-up microbots are
capable of “the selective loading, transportation,
and delivery of microscale objects in a
fluid.” Like Martel’s technology, external magnets control the motion
of these tubes. However, these microbots are also propelled by microbubbles.
The tubes are partially filled with hydrogen peroxide, which, in
a reaction catalyzed by the platinum, decomposes into oxygen and water.
24 Yale Scientific Magazine | January 2013 www.yalescientific.org