Cancer affects all of us,
especially the ones that come back over and over again.
The highly invasive and drug-resistant ones,
the ones that defy medical treatment,
even when we throw our best drugs at them.
Engineering at the molecular level,
working at the smallest of scales,
can provide exciting new ways
to find the most aggressive forms of cancer.
Cancer is a very clever disease.
There are some forms of cancer,
which, fortunately, we've learned how to address relatively well
with known and established drugs and surgery.
But, there's some forms of cancer that don't respond
to these approaches
and the tumor survives or comes back,
even after an onslaught of drugs.
We can think of these very aggresive forms of cancer
as kind of super villains in a comic book.
They're clever, they're adaptable,
and they're very good at staying alive.
And, like most super villains these days,
their super powers come from a genetic mutation.
The genes that are modified inside these tumor cells
can enable and encode for new and unimagined modes of survival,
allowing the cancer cell to live through
even our best chemotherapy treatments.
One example is a trick in which a gene allows
a cell, even as the drug approaches the cell,
to push the drug out before the drug can have any effect.
Imagine the cell effectively spits out the drug.
This is just one example of the many genetic tricks
in the bad of our super villain, cancer.
All due to mutant genes.
So, we have a super villain with incredible super powers
and we need a new and powerful mode of attack.
Actually, we can turn off a gene,
the key is a set of molecules called siRNA.
siRNA are short sequences of genetic code
that guide a cell to block a certain gene.
Each siRNA molecule can turn off a specific gene
inside the cell.
For many years since its discovery,
scientists have been very excited
about how we can apply these gene blockers in medicine.
But, there is a problem.
siRNA works well inside the cell.
But if it gets exposed to the enzymes that reside
in our bloodstream and our tissues,
it degrades within seconds.
It has to be packaged, protected through its journey through the body
on its way to its final target inside the cancer cell.
So, here's our strategy:
first, we'll dose the cancer cell with siRNA, the gene blocker,
and silence those viral genes,
and they'll we'll whap (?) it with a chemo drug.
But how do we carry that out?
Using molecular engineering,
we can actually design a super weapon
that can travel through the blood stream.
It has to be tiny enough that it can get through the blood stream,
it's got to be small enough to penetrate the tumor tissue,
and it's got to be tiny enough to be taken up
inside the cancer cell.
To do this job well, it has to be about one 100th the size
of a human hair.
Let's take a closer look at how we can build this nanoparticle.
First, let's start with the nanoparticle core.
It's a tiny capsule that contains the chemotherapy drug.
This is the poison that will actually end the tumor cell's life.
Around this core, we'll wrap a very thin,
nanometer-think blanket of siRNA.
This is our gene blocker.
Because siRNA is strongly negatively charged,
we can protect it with a nice protect layer
of postively charged polymer.
The two oppositely charged molecules stick together throough charge attracttion,
and that provides us with a protective layer