The Scientist - USA (2020-04)

Autonomous, living microrobots that seek and destroy cancer are not as futuristic

as one might imagine, thanks to the fusion of robotics and synthetic biology.

BY SIMONE SCHUERLE AND TAL DANINO

Bacteria Ta k e

On Cancer

I

n the 1966 movieFantastic Voyage, a team of scientists is shrunk to

fit into a tiny submarine so that they can navigate their colleague’s

vasculature and rid him of a deadly blood clot in his brain. This clas-

sic film is one of many such imaginative biological journeys that have

made it to the big screen over the past several decades. At the same

time, scientists have been working to make a similar vision a reality:

tiny robots roaming the human body to detect and treat disease.

Although systems with nanomotors and onboard computation

for autonomous navigation remain fodder for fiction, research-

ers have designed and built a multitude of micro- and nanoscale

systems for diagnostic and therapeutic applications, especially in

the context of cancer, that could be considered early prototypes

of nanorobots. Since 1995, more than 50 nanopharmaceuticals,

basically some sort of nanoscale device incorporating a drug, have

been approved by the US Food and Drug Administration. If a drug

of this class possesses one or more robotic characteristics, such as

sensing, onboard computation, navigation, or a way to power itself,

scientists may call it a nanorobot. It could be a nanovehicle that car-

ries a drug, navigates to or preferentially aggregates at a tumor site,

and opens up to release a drug only upon a certain trigger. The first

approved nanopharmaceutical was DOXIL, a liposomal nanoshell

carrying the chemotherapeutic drug doxorubicin, which nonselec-

tively kills cells and is commonly used to treat a range of cancers.

The intravenously administered nanoshells preferentially accu-

mulate in tumors, thanks to a leaky vasculature and inadequate

drainage by the lymphatic system. There, the nanoparticles slowly

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