How Nanotechnology Can Revolutionize Medicine (Guest Post)
For all its wonders, modern medicine has been insufficient at treating many diseases, and medical advancement has even slowed in recent decades.
And that's where nanotechnology can help! Nanotechnology - technology that deals with dimensions between several atoms and 100 nanometers (1 nanometer = 1 billionth of a meter) - was first proposed in 1959 by Nobel Laureate Richard Feynman in his seminal talk There's Plenty of Room at the Bottom.
Since then, nanotechnology has advanced considerably and is in the process of revolutionizing various industries, from energy to computing.
Arguably the largest potential that nanotechnology holds is in its capabilities to improve medicine.
There are many theoretical reasons that nanotechnology will likely be a boon for medicine.
First, nanotechnology deals with manipulating matter on the nanoscale, and most processes of life - including most diseases and aging - fundamentally occur on that scale (biologically, this is the subcellular level).
Under the most technical sense of the word, all life is actually nanotechnology - we're all machines with parts that operate on the nanoscale. It's sensible that the best way to influence processes on this scale is by building our own nanomachines.
Second, nanotechnology allows for unprecedented control over the properties of materials. On the nanoscale, changing the structure of materials allows for tailoring their properties. For instance, changing the size and shape of carbon nanotubes allows for changing them between metals and semiconductors. This is due to peculiarities of quantum mechanics - on small length scales, the magnitudes of these lengths affect how particles (such as electrons) behave.
This is quite different from our human-scale world, where (for example) making a brick twice as big doesn't really change the brick's properties.
More advanced nanotechnology also allows us to create nanosystems where different parts interact with each other on the nanoscale, giving rise to complicated behavior.
By allowing us to tailor the properties and function of materials such that they act the way we want on the subcellular level, nanotechnology presents many opportunities.
While nanomedical research is relatively new, it has already shown many exciting results. One of the most exciting areas of current research is in combating cancer.
Cancer can be thought of as out of control cellular growth. As cancer cells grow and replicate without bound, they eventually interfere with the function of normal cells.
Cancer drugs attempt to attack these cancerous cells. Unfortunately, it's hard to target just the cancer cells, so these drugs are often poisonous to normal cells as well. Dosage is then typically a tradeoff between poisoning cancer cells and poisoning normal cells.
Luckily, nanotechnology can enable much more precise targeting of cancer cells. For example, cancer cells tend to consume lots and lots of Vitamin B9 in an effort to grow quickly. Scientists have created many types of nanoparticles that combine this vitamin and cancer drugs. For instance, both of these have been simultaneously attached to carbon nanotubes.
The resulting nanomedicine acts a bit like a Trojan Horse. The cancer cells eagerly eat up the vitamin, and in the process also consume the toxic drug.
Scientists can also improve the imaging of cancer by additionally attaching imaging agents (such as iron oxide nanocrystals) to these nanoparticles. This would be like if Odysseus gave GPS devices to the warriors inside the Trojan Horse. By monitoring the warriors' movements once inside the city, he could learn the layout of Troy.
Cancer has proven to be a particularly difficult disease to fight. A drug can wipe out 99% of the cancer cells, but the cancer will likely come back, immune to this drug. It's a bit like an arms race, though nanotechnology has shown much progress.
Similar tools have also shown promise in fighting other diseases as well - such as heart disease and Alzheimer's disease. And scientists are making strides in creating, improving, and integrating various nanoscale devices, including: molecular switches, nanomotors, and even simple molecular machines.
Arguably the most impressive examples of nanomedicine today use something known as DNA Origami.
Before we dig into DNA origami, let's quickly review the structure of DNA.
Typically DNA consists of two strands, which are held together by a series of base pairs.
These base pairs have four variations: A, T, G, and C. A binds with T, and G binds with C. So if one strand has a sequence that goes "AATG", it will bind with one that goes "TTAC" (and the two strands are complimentary).
DNA origami allows for scientists to create arbitrary shapes out of DNA.
To create DNA origami of a particular shape, we first create one long strand that will fill the body of the shape (we have the technology to synthesize DNA in any sequence we want).
The desired shape may require two regions of this long strand (which we will call X and Y) to be next to each other, despite not naturally being next to each other.
In order for the long strand to achieve the desired shape, we would need to "staple" X to Y. We accomplish this using a short "staple strand" of DNA. The staple strand is synthesized such that the beginning of its base pair sequence binds to X and the end of its sequence binds to Y, holding X and Y together.
By creating lots of staple strands that staple the long strand in specific locations, almost any shape can be created.
The first publication about DNA origami (by CalTech Prof. Paul Rothemund in 2006) demonstrated the ability to create various shapes.
Since then, we've increased our ability to make more and more complicated structures out of DNA origami.
And the really cool thing is that scientists have used this technique to create medical nanorobots.
One group was able to make a chest out of DNA origami. They additionally put strands on the inside of the chest that would bind to specific drugs, keeping the drugs inside the chest. On the "front" of the chest, they put a lock.
The lock consisted of strands that bound the top of the chest to the bottom that were almost complimentary. Imagine how the strand AATG almost binds perfectly to TTCC. So the strands would generally keep the chest shut.
But the strands bound even better to particular molecules that tend to be found in certain cancer cells (the "key"). The idea was that in the presence of these cells, the strands would bind to those molecules instead, opening up, and releasing the drug.
When the scientists tested these nanorobots on cancer cells and healthy cells in a petri dish, they found that in healthy cells, the chest stayed closed, keeping the drugs inside. But in cancer cells, the chest opened, releasing the drugs.
And more recently, work on DNA origami nanorobots has allowed for even more complicated behavior. Scientists realized the "payload" inside one nanorobot could be the "key" to open another nanorobot. Additional payloads in other nanorobots could clamp further nanorobots shut (not allowing them to open, even in the presence of their keys). By having a swarm of various types of nanorobots, they were able to implement universal computing inside a live cockroach.
Looking To The Future
Extensions of current nanomedicine paints a picture in which increasingly precise and targeted therapies are able to act in more complicated ways - potentially even following sophisticated algorithms.
Where do extensions of these nanotechnologies lead?
In the short and medium term, nanotechnology offers the possibility of treating and even curing many diseases, while decreasing side effects, turning around the recent slow progress in medicine.
In the much longer term, nanotechnology may even allow us to go further than that, combating aging and allowing for human enhancement.
Recent work has demonstrated the possibility of combating aging. When mice were cleared of senescent cells (cells that have "retired" and stopped dividing) via bioengineering methods, these mice lived longer than normal mice. Crucially, these mice further stayed healthier longer.
Aging is, fundamentally, changes in the nanoscale organization of matter in an organism that leads to decreased capabilities and increased chance of death. Much of the ravages of aging may be caused by a genetic program running, though the genetic program itself is stored as the organization of matter on the nanoscale (in DNA).
To the best available knowledge today, there is no theoretical reason that advanced nanotechnology would not be able to reorganize this matter to even reverse the aging process and keep humans as healthy and fit as 25 year olds.
On the augmentation front, the coolest capabilities deal with interfacing with the human brain.
MIT Professor Nicholas Negroponte (cofounder of the MIT Media Lab and co-creator of Wired Magazine) predicts that eventually, nanorobots could access every neuron in your brain through your bloodstream. These nanorobots could allow you to "learn" Shakespeare or French by depositing information in the appropriate places in your brain. (Though Prof. Negroponte also posits that he won't be around to see this - he's 73.)
Similarly, nanorobots within the brain may allow people to experience virtual reality, all while lying down with their eyes closed.
Of course, we're a long way away from these technological capabilities - decades at least. But if 200 years from now you're still alive and living in your own personal virtual utopia created from nanorobots in your brain, you'll have nanotechnology to thank.
Guest post by Daniel Eth. Daniel is a PhD student at UCLA performing computational nanotechnology research. He runs the blog thinkingofutils.com where he posts about science, technology, and economics.