Nanotechnology, the manipulation of matter at the atomic and molecular scale to create materials with remarkably varied and new properties, is a rapidly expanding area of research with huge potential in many sectors, ranging from healthcare to construction and electronics. In medicine, it promises to revolutionize drug delivery, gene therapy, diagnostics, and many areas of research, development and clinical application.
What is Nanotechnology?
The prefix "nano" stems from the ancient Greek for "dwarf". In science, it means one-billionth (10 to the minus 9) of something, thus, a nanometer (nm) is one billionth of a meter, or 0.000000001 meters. A nanometer is about three to five atoms wide, or some 40,000 times smaller than the thickness of human hair. A virus is typically 100 nm in size.
The ability to manipulate structures and properties at the nanoscale in medicine is like having a sub-microscopic lab bench on which you can handle cell components, viruses or pieces of DNA, using a range of tiny tools, robots and tubes.
Manipulating DNA Therapies that involve the manipulation of individual genes, or the molecular pathways that influence their expression, are increasingly being investigated as an option for treating diseases. One highly sought goal in this field is the ability to tailor treatments according to the genetic make-up of individual patients.
This creates a need for tools that help scientists experiment and develop such treatments.
Imagine, for example, being able to stretch out a section of DNA like a strand of spaghetti, so you can examine or operate on it, or building nanorobots that can "walk" and carry out repairs inside cell components. Nanotechnology is bringing that scientific dream closer to reality.
For instance, scientists at the Australian National University have managed to attach coated latex beads to the ends of modified DNA, and then using an "optical trap" comprising a focused beam of light to hold the beads in place, they have stretched out the DNA strand in order to study the interactions of specific binding proteins.
Nanobots and Nanostars
Meanwhile chemists at New York University (NYU) have created a nanoscale robot from DNA fragments that walks on two legs just 10 nm long. In a 2004 paper published in the journal Nano Letters, they describe how their "nanowalker", with the help of psoralen molecules attached to the ends of its feet, takes its first baby steps: two forward and two back.
One of the researchers, Ned Seeman, said he envisages it will be possible to create a molecule-scale production line, where you move a molecule along until the right location is reached, and a nanobot does a bit chemisty on it, rather like "spot-welding" on a car assembly line. Seeman's lab at NYU is also looking to use DNA nanotechnology to make a biochip computer, and to find out how biological molecules crystallize an area that is currently fraught with challenges.
The work that Seeman and colleagues are doing is a good example of "biomimetics", where with nanotechnology they can imitate some of the biological processes in nature, such as the behavior of DNA, to engineer new methods and perhaps even improve them.
DNA-based nanobots are also being created to target cancer cells. For instance, researchers at Harvard Medical School in the US reported recently in Science how they made an "origami nanorobot" out of DNA to transport a molecular payload. The barrel-shaped nanobot can carry molecules containing instructions that make cells behave in a particular way. In their study, the team successfully demonstrates how it delivered molecules that trigger cell suicide in leukemia and lymphoma cells.
Nanobots made from other materials are also in development. For instance, gold is the material scientists at Northwestern University use to make "nanostars", simple, specialized, star-shaped nanoparticles that can deliver drugs directly to the nuclei of cancer cells. In a recent paper in the journal ACS Nano, they describe how drug-loaded nanostars behave like tiny hitchhikers, that after being attracted to an over-expressed protein on the surface of human cervical and ovarian cancer cells, deposit their payload right into the nuclei of those cells.
The researchers found giving their nanobot the shape of a star helped to overcome one of the challenges of using nanoparticles to deliver drugs: how to release the drugs precisely. They say the shape helps to concentrate the light pulses used to release the drugs precisely at the points of the star.
Preventing Heart Disease
One of the major killers in our time is heart disease. There are several efforts going on in this area. Researchers at the University of Santa Barbara have developed a nanoparticle that can deliver drugs to plaque on the wall of arteries. They attach a protein called a peptide to a nanoparticle which then binds with the surface of plaque. Studies have verified that the peptide attaches the nanoparticle to plaque. The researchers plan to use these nanoparticles to deliver imaging particles and drugs to both diagnosis and treat the condition.
Researchers at MIT and Harvard Medical School have attached a different peptide to a drug-carrying nanoparticle. This peptide binds to a membrane that is exposed in damaged artery walls, allowing the nanoparticle to release a drug at the site of the damage. The drug helps prevent the growth of scar tissue that can clog arteries. For more about this, see the article at this link.
To help coordinate this type of research, the U.S. National Heart Lung and Blood Institute has established four Program of Excellence in Nanotechnology Centers to focus on diseases of the lung and cardiovascular system. The scientists are developing methods to detect, monitor, treat, and eliminate "vulnerable" plaque, the type of plaque most likely to cause heart attacks.
Researchers at MIT have developed a sensor using carbon nanotubes embedded in a gel; that can be injected under the skin to monitor the level of nitric oxide in the bloodstream. The level of nitric oxide is important because it indicates inflammation, allowing easy monitoring of inflammatory diseases. In tests with laboratory mice the sensor remained functional for over a year.
Researchers at the University of Michigan are developing a sensor that can detect a very low level of cancer cells, as low as 3 to 5 cancer cells in a one milliliter in a blood sample. They grow sheets of graphene oxide, on which they attach molecules containing an antibody that attaches to the cancer cells. They then tag the cancer cells with fluorescent molecules to make the cancer cells stand out in a microscope.
Researchers have demonstrated a way to use nanoparticles for early diagnosis of infectious disease. The nanoparticles attach to molecules in the blood stream indicating the start of an infection. When the sample is scanned for Raman scattering the nanoparticles enhance the Raman signal, allowing detection of the molecules indicating an infectious disease at a very early stage.
A test for early detection of kidney damage is being developed. The method uses gold nanorods functionalized to attach to the type of protein generated by damaged kidneys. When protein accumulates on the nanorod the color of the nanorod shifts. The test is designed to be done quickly and inexpensively for early detection of a problem.
Life Extension and Nanomedicine
There is no doubt, that the advance in medicine and overall progress in diagnostics and treatment, can be directly linked to the expected life extension. Indeed, future advances in nanomedicine could give rise to life extension through the repair of many processes thought to be responsible for aging. K. Eric Drexler, one of the founders of nanotechnology, postulated cell repair machines, including ones operating within cells and utilizing yet hypothetical molecular computers, in his 1986 book Engines of Creation. Raymond Kurzweil, a futurist and transhumanist, stated in his book The Singularity Is Near that he believes that advanced medical nanorobotics could completely remedy the effects of aging by 2030.
In an interview with Computerworld in 2009, Ray Kurzweil said that anyone alive come 2040 or 2050 could be close to immortal. The quickening advance of nanotechnology means that the human condition will shift into more of a collaboration of man and machine, as nanobots flow through human blood streams and eventually even replace biological blood, he added.
That may sound like something out of a sci-fi movie, but Kurzweil, a member of the Inventor's Hall of Fame and a recipient of the National Medal of Technology, says that research well underway today is leading to a time when a combination of nanotechnology and biotechnology will wipe out cancer, Alzheimer's disease, obesity and diabetes.
Cloning and body part replacement
Some life extensionists suggest that therapeutic cloning and stem cell research could one day provide a way to generate cells, body parts, or even entire bodies (generally referred to as reproductive cloning) that would be genetically identical to a prospective patient. Recently, the US Department of Defense initiated a program to research the possibility of growing human body parts on mice. Complex biological structures, such as mammalian joints and limbs, have not yet been replicated. Dog and primate brain transplantation experiments were conducted in the mid-20th century but failed due to rejection and the inability to restore nerve connections. As of 2006, the implantation of bio-engineered bladders grown from patients' own cells has proven to be a viable treatment for bladder disease. Proponents of body part replacement and cloning contend that the required biotechnologies are likely to appear earlier than other life-extension technologies.
The use of human stem cells, particularly embryonic stem cells, is controversial. Opponents' objections generally are based on interpretations of religious teachings or ethical considerations. Proponents of stem cell research point out that cells are routinely formed and destroyed in a variety of contexts. Use of stem cells taken from the umbilical cord or parts of the adult body may not provoke controversy.
The controversies over cloning are similar, except general public opinion in most countries stands in opposition to reproductive cloning. Some proponents of therapeutic cloning predict the production of whole bodies, lacking consciousness, for eventual brain transplantation.
Other Ethical Issues
It is likely that some conditions will be treated most easily by modifying the body's genetic material. Many people are disturbed by this idea, especially if the modification is transmissible to offspring. However, once we have a nanotechnology that can directly manipulate the genes, transmission of modified genes need not be a cause for concern. Any genetic manipulation that turns out to be a bad idea will be reversible. Furthermore, it would be trivial to edit the DNA of any offspring while still in embryo stage in order to remove the modifications. The idea that a genetic modification will irreversibly change the whole species becomes incorrect once genes can easily be directly manipulated.
A common objection to life extension is that if everyone lives forever, the earth will become overcrowded. However, a little math will demonstrate that the earth can become overcrowded much faster due to excess births than due to reduced death. If everyone killed themselves after 80 years of life, that act would remove only one person from the population; meanwhile their children and grandchildren would be reproducing. However, a person who chose to live a long time and have one fewer child would be reducing the population by more than one, since a nonexistent person cannot have children. (Robert J. Bradbury points out that nanotechnology will also give us cheaper access to space. Using a basic design, it would be feasible for earth's entire population to leave the earth and live in space.)
Today, people are kept alive for years in terrible health, sometimes beyond the point where they wish to die. This has given life extension a bad reputation. Merely extending life without improving health is often a bad idea. The good news is that if health is improved, life will naturally be extended. Once we have the technology to eliminate diseases, we need no longer worry about living on in bad health.
It has been argued that it would be selfish for some people to extend their lives when the technology is not available to everyone. However, life extension will not be a single technology hoarded by an elite--instead, it will be a natural consequence of health maintenance. Inequities in availability of health care are widespread today, and curing more diseases will not make the problem worse. On the other hand, development of more effective medical tools will reduce the cost of medical care. If you want to increase the availability and reduce the cost of a technology, you should invest in research and development, and buy more technology. The more people who make use of health maintenance technologies, the faster they will become cheap and widely available.
Some people have claimed that nanotech itself is extremely risky, and thus any development or use of it must be constrained. This argument rests on the idea that tiny self-replicating nanobots appear to be possible, and that a rogue self-replicator could eat the planet. This argument does not apply to medical nanotech. There is no reason to use self-replication for medical nanodevices; it would only make them needlessly complex and more prone to failure. A medical nanodevice would simply be a machine like any other, no more capable of running amok than a television. The factories used to build the nanobots might be self-replicating, but a factory is equally unlikely to run amok.
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