这是一条人体的血管。
This is a blood vessel in the body.
包裹着血管的就是肿瘤。
Surrounding the blood vessel is a tumor.
我们将要把纳米颗粒注射进血管，并观察它们如何随着血流进入肿瘤。
We're going to inject nanoparticles into the blood vessel and watch how they travel from the bloodstream into the tumor.
事实证明有许多肿瘤的血管是有漏洞的,所以纳米颗粒可以从血流渗漏到肿瘤中。
Now it turns out that the blood vessels of many tumors are leaky, and so nanoparticles can leak out from the bloodstream into the tumor.
它们是否能渗透出去取决于它们的尺寸。
Whether they leak out depends on their size.
在这张图中，较小的百纳米尺寸的蓝色纳米颗粒正在渗漏至血管外，大一点的500纳米的红色颗粒被困在了血管中。
So in this image, the smaller, hundred-nanometer, blue nanoparticles are leaking out, and the larger, 500-nanometer, red nanoparticles are stuck in the bloodstream.
所以这对于工程师来说，取决于我所制造的材料的大小，我可以控制它能够去你身体里的哪一部分。
So that means as an engineer, depending on how big or small I make a material, I can change where it goes in your body.
在我的实验室，我们最近研制出了一种癌症纳米检测器，小到可以进入全身血液循环并寻找肿瘤。
In my lab, we recently made a cancer nanodetector that is so small that it could travel into the body and look for tumors.
我们设计它用于监听肿瘤的侵袭：即肿瘤扩散所需要的化学信号。
We designed it to listen for tumor invasion: the orchestra of chemical signals that tumors need to make to spread.
一个肿瘤冲破包围它的组织时，它需要产生一种叫做酶的化学物质来分解组织的组成结构。
For a tumor to break out of the tissue that it's born in, it has to make chemicals called enzymes to chew through the scaffolding of tissues.
我们设计了这些会被酶激发的纳米颗粒。
We designed these nanoparticles to be activated by these enzymes.
一个酶每小时可激发一千个这种化学反应。
One enzyme can activate a thousand of these chemical reactions in an hour.
用工程术语来描述的话，我们叫它1比1000的放大比例，这就形成了一种超级灵敏的东西。
Now in engineering, we call that one-to-a-thousand ratio a form of amplification, and it makes something ultrasensitive.
所以我们已经做了一个超灵敏的癌症检测器。
So we've made an ultrasensitive cancer detector.
好，但是还有另一个问题。
OK, but there's one more problem.
这是个小而微弱的信号，我怎么来检测它？
This is a tiny little signal, so how do I detect it?
实际上，信号就是一个分子。
Well, the signal is just a molecule.
它们是我们作为工程师设计的分子。
They're molecules that we designed as engineers.
它们完全人工合成并且我们可以设计它们，所以它们和我们选用的工具相匹配。
They're completely synthetic, and we can design them so they are compatible with our tool of choice.
如果我们想使用一种非常灵敏先进的仪器叫做质谱仪，那我们可以让这个分子有一个独特的质量。
If we want to use a really sensitive, fancy instrument called a mass spectrometer, then we make a molecule with a unique mass.
或者我们也许想要研制出一种更加便宜和便于携带的分析方式。
Or maybe we want make something that's more inexpensive and portable.
那我们就制造出可以滞留在纸上的分子，就像测孕试纸。
Then we make molecules that we can trap on paper, like a pregnancy test.
实际上试纸的应用已经非常广泛，以至于专门形成了试纸诊断领域。
In fact, there's a whole world of paper tests that are becoming available in a field called paper diagnostics.
那好，我们现在进展如何呢？
Alright, where are we going with this?