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In my lab, we recently made a cancer nanodetector
在我的实验室，我们最近研制出了一种癌症纳米检测器，
that is so small that it could travel into the body and look for tumors.
小到可以进入全身血液循环并寻找肿瘤。
We designed it to listen for tumor invasion:
我们设计它用于监听肿瘤的侵袭：
the orchestra of chemical signals that tumors need to make to spread.
即肿瘤扩散所需要的化学信号。
For a tumor to break out of the tissue that it's born in,
一个肿瘤冲破包围它的组织时，
it has to make chemicals called enzymes to chew through the scaffolding of tissues.
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。
We designed these nanoparticles to be activated by these enzymes.
我们设计了这些会被酶激发的纳米颗粒。
One enzyme can activate a thousand of these chemical reactions in an hour.
一个酶每小时可激发一千个这种化学反应。
Now in engineering, we call that one-to-a-thousand ratio a form of amplification,
用工程术语来描述的话，我们叫它1比1000的放大比例，
and it makes something ultrasensitive.
这就形成了一种超级灵敏的东西。
So we've made an ultrasensitive cancer detector.
所以我们已经做了一个超灵敏的癌症检测器。
OK, but how do I get this activated signal to the outside world, where I can act on it?
好的，但我如何把这激发信号传递到外界，好方便对其进行分析呢？
For this, we're going to use one more piece of nanoscale biology, and that has to do with the kidney.
针对这个问题，我们将采用另一项纳米生物技术，与肾脏有关。
The kidney is a filter.
肾脏就是一个过滤装置。
Its job is to filter out the blood and put waste into the urine.
它的工作是把血液中的废物，过滤出来形成尿液。
It turns out that what the kidney filters is also dependent on size.
事实发现肾脏的过滤系统也是依据（过滤物的）大小。
So in this image, what you can see is that everything smaller than five nanometers
所以在这个图中，你可以看到所有小于5纳米的东西
is going from the blood, through the kidney, into the urine,
都会从血液穿过肾，变成尿液，
and everything else that's bigger is retained.
其他所有更大尺寸的会留下来。
OK, so if I make a 100-nanometer cancer detector,
好，那如果我制造一个100纳米的癌症检测装置，
I inject it in the bloodstream,
注射到血流中，
it can leak into the tumor where it's activated by tumor enzymes to release a small signal
它可以渗漏到肿瘤，并被肿瘤的酶激发，释放出很小的信号，
that is small enough to be filtered out of the kidney and put into the urine,
小到可以被肾脏过滤出来并进入尿液中。
I have a signal in the outside world that I can detect.
我就有了一个可以在体外探测到的信号。
OK, but there's one more problem.
好，但是还有另一个问题。
This is a tiny little signal, so how do I detect it?
这是个小而微弱的信号，我怎么来检测它？
Well, the signal is just a molecule.
实际上，信号就是一个分子。
They're molecules that we designed as engineers.
它们是我们作为工程师设计的分子。
They're completely synthetic, and we can design them
它们完全人工合成并且我们可以设计它们，
so they are compatible with our tool of choice.
所以它们和我们选用的工具相匹配。
If we want to use a really sensitive, fancy instrument called a mass spectrometer,
如果我们想使用一种非常灵敏先进的仪器叫做质谱仪，
then we make a molecule with a unique mass.
那我们可以让这个分子有一个独特的质量。
Or maybe we want make something that's more inexpensive and portable.
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。
Then we make molecules that we can trap on paper, like a pregnancy test.
那我们就制造出可以滞留在纸上的分子，就像测孕试纸。
In fact, there's a whole world of paper tests
实际上试纸的应用已经非常广泛，
that are becoming available in a field called paper diagnostics.
以至于专门形成了试纸诊断领域。
