Quantum dots are particles of semiconductors that are a few nanometers [billionths of a meter] in size. We can choose the color of light that they generate. In fact we can program them to produce colors that are very pure and consequently very distinctive. We can use a camera and look for a particular, pure orange color and know exactly where our quantum dots are.
That idea is central to trying to diagnose disease, and cancer is a great example, because you can see where the dots are.
So you put something on the surface of these little particles such that they will stick only to, let's say, human prostate cancer cells. This is something that has already been demonstrated in a lab. You could detect cancer at a stage when there are perhaps only a thousand cells that have gone bad. Compare that with what we do in hospitals today where you have an MRI or a CT scan, and you see tumors once they are an inch [two and a half centimeters] in size and they already have a billion [cancerous] cells.
And how could nanotechnology improve the way cancer is healed?
Targeting is the key word. What we want to do is attack the tumor and not attack the whole patient. Deliver drugs to the bad cells as opposed to every cell. And we want to target in time. Your body will respond to certain cancer drugs better if they're administered in, say, slow release over four weeks than if it's just a one-shot chemotherapy that's delivered to you in an instant and then you get your next dose two to three weeks later.
You can immediately say there will be fewer side effects to the patient as a result. But maybe the even more remarkable thing is that if you can avoid those side effects, you can also deliver many times the concentration of drugs, because you're just going after the cells that you do want to destroy.
Let's switch to the realm of energy. Give us a sense of the possibilities that solar power holds and how nanotechnology can help us tap into that.
The most important thing about solar energy is that there's enough of it. There's ten thousand times more solar power than we need for all our energy. The idea is to cover some fraction of the Earth with solar cells, and use those to convert optical power into, let's say, electricity or a kind of fuel [such as] hydrogen fuel that can be subsequently used. But we have to do that cost-effectively.
With today's flexible solar cells based on plastics, we can capture the sun's visible light, but we don't capture the invisible light. My group has developed solar cells based on paintable quantum dots, which not only capture the visible [light] but also capture the infrared photons. As a result they double the amount of power coming from the sun that we actually absorb in our solar cells compared to existing solar material solutions.
In the area of information technology, you talk about a technological barrier that we will hit, which only nanotechnology can overcome.
The technological advancements that we have seen in recent decades are often [governed by] Moore's Law. [According to this empirical observation, the rate of technological development doubles every 18 months.] We've managed to make computer chips smaller and smaller, and crammed more in there, so the complexities of our computers have kept going up.
This advancement has been remarkable. But there are some limits that we are starting to get quite close to already. You reach a point when you can no longer guarantee that each one of your 16 million transistors on your chip actually works, and therefore potentially whether the chip itself works.
So people in the bottom-up world of nanotechnology are asking, Could we ever make a chip that did what we wanted it to do, but instead of us putting every transistor in place we built computer chips where nature organized molecules? Each molecule might function like a transistor.
You warn that nanomaterials could have negative environmental and health effects as well.
Any technology that is powerful can have downsides. We may not understand the world of atoms and molecules well enough yet to know exactly what those are going to be. We don't have complete predictive control over the properties of our materials, so toxicity is a really important area for nanotechnology research. Fortunately, there are some really outstanding people looking at exactly those questions right now, and they're doing it through experiments. It's really important to the field.
You talk about how nanotechnology is revolutionizing science by incorporating all these different fields of studybiology, chemistry, information science, engineering.
When I started doing my Ph.D. ten years ago, I never would have dreamed of how things are now. [Scientists have] become very problem-focused. What are society's big problems? Cancer, energy, communication between cultures, global interaction. We must find the tools to solve these problems, and we'll do that however it has to be done. If that means we have to learn more biology or we have to discover some new chemistry, we'll do that.
But the only way to do that is as a team of people working very closely with each other, and that's changing the way science is being done. The cultural aspects of doing work in [nanoscience] are actually some of the most revolutionary things about it.
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