3D printing organs for transplant

A reported 10,000 people die in the US every year, that's 27 people each day, due to lack of organs available for transplant. The solution to this problem is not to make 27 more people donate their organs every day, but to use bioengineering to manufacture organs. This seems like a daunting task, but it could be made possible with 3D printing.

Conventional 3D printers are commonly used in the manufacturing and design industry, but are used to print objects for the purpose of testing, not for the purpose of printing objects to be used or sold. These printers add layers of modeling material on top of each other, creating shapes that would be difficult to make out of a single, or small number of pieces using traditional manufacturing methods. They can also print directly from CAD models, making it easy to model designs.

Despite its success in this field, this application of 3D printers is not the only one. Engineers at AMTecH group are working on 3D printing human organs. AMTecH plans to print fully working human organs within the next ten years, a goal that co-director Tim Marler says is “not far-fetched.” One organ that is being developed is pancreatic organ that can be placed anywhere in the body to monitor the glucose level of blood. This is essentially the addition of a new organ to the human body, and would be an important advancement in both medical engineering and 3D printing. Dr. Anthony Atala at the Wake Forest Institute for Regenerative Medicine also is working on printing organs. The surgeon's team developed the first organ that was implemented into a human body more than ten years ago. Now, his work has mainly focused on the development of a human kidney, the most commonly transplanted organ that is also in the most demand. The production of an artificial kidney would give many people another chance to live.

To be able to print human organs, the engineers have pushed aside the conventional single armed printers and built their own multiple-armed printer. One of the reasons that the multi-armed printer is so much better than any other is that multiple arms allow it to print multiple materials at once, with each arm printing a different part of the organ, such as blood vessels, while another arm is printing different types of cells between the blood vessels. This makes it so that one arm doesn't have to keep switching the type of material that it is printing, saving time, a precious resource when working on an organ.

Another body part that is being 3D printed is the human ear. Humans can lose their ears in a variety of ways, some people are born without them, some people lose their ears to disease, and some people lose them to accidents. Luckily, with 3D printing, a new ear can be grown in two days, and , can be successfully integrated into the body. To do this, a patient with one ear can have it scanned, or a patient missing both ears can have an appropriate ear designed or scanned for them. Then a mold will be printed of the person's ear, saving time over carving a mold. Afterwards, the mold is injected with a gel made of living cow ear cells and collagen, and after 15 minutes the gel will set, be implanted, and begin to grow. The ear is not the only body part that could be printed using this method, and after the ear is expected to be integrated into the first human in three years, more 3D printed molds for other body parts will likely be developed.

Biological 3D printing is still in its infancy, but the new applications could have an important impact on medicine. Being one of the most versatile forms of manufacturing today, it is an effective platform for the development of bioengineering products, especially ones tailored to fit specific people.

Sources:

http://phys.org/news/2013-03-3d-printer-bio-ink-human-video.html

http://www.designboom.com/technology/3d-printed-organs-from-regenerative-living-cells/

http://www.livescience.com/27280-3d-printed-ear-created.html

http://www.sup.org/book.cgi?id=22523

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Carbon nanotubes at the frontiers of microprocessing

A Carbon Nanotube being used as a transistor

Silicon computer processors are starting to reach their limits. Moore's law states that every 12-18 months the processing power of a computer microchip is doubled. For this law to continue, transistors have to keep getting smaller, a feat that has been going on with silicon for long enough. The use of carbon nanotube transistors as opposed to silicon transistors allows them to be made much smaller than the smallest, 22 nanometer (nm), silicon Intel Ivy Bridge transistors. Carbon nanotubes (CNTs) can be made into transistors as small as 9 nm currently, with the potential to be made far smaller. CNT chips are also much more energy efficient than silicon chips.

Although carbon nanotube transistors have been created, they had not been integrated into anything as complex as a robot until now. Researchers at Stanford University have developed the first robot integrated with a carbon nanotube chip and circuitry. The robot, Sacha, was shown at the 2013 International Solid-State Circuits Conference.The robot contained a carbon nanotube capacitor, a device found in many touchscreens, connected to another nanotube circuit, which turned the analog signal from the capacitor into a digital signal, which was transmitted to the microprocessor that contained CNT transistors. The microporcessor then sent a signal to a motor on the hand of the robot, which shook the person's hand that touched the capacitors embedded in it.

This is not the first example of carbon nanotube circuitry, but it is the first example of CNTs being produced at mass for a microprocessor and circuit that were integrated. This advancement showed that it is possible to produce mass amounts of CNTs and have them integrate succesfully into a complex system. Although the size of the CNTs in this system are far from the optimal size of 10nm, it is a good starting point, and the nanotubes still can be much further refined.

Carbon nanotubes, although perfect in theory for microprocessors, present new challenges for engineers. The greatest challenge is the actual integration of CNTs into circuitry. Nanotubes often force themselves into a tangled position, which can cause circuits to fail without warning. This will always be a problem, so the solution is to create adaptive error-tolerant environments for the nanotubes to be integrated into. Chip designers working with the new transistors would "build up the circuit complexity, then go back to improving the building methods, then make more complex circuits," according to Prof. Philip Wong of Stanford University, who worked on the CNT-controlled robot.

The challenges that engineers working with CN T transistors face are similar to the ones of early silicon chips. Over time, solutions will be created, and once CNTs are able to be integrated into chips in a cost effective way, they will take over for silicon in the fight to keep Moore's law alive.

http://www.digitaltrends.com/mobile/carbon-nanotubes-could-power-the-next-generation-of-processors/

http://www.pcgamer.com/2012/11/01/ibm-carbon-nanotube-transistors-could-make-cpus-five-to-ten-times-faster-than-todays-silicon-chips/

http://www.stanforddaily.com/2013/03/07/stanford-researchers-debut-first-robot-run-by-carbon-nanotube-transistors/

http://www.technologyreview.com/news/511746/stanford-researchers-build-complex-circuits-made-of-carbon-nanotubes/

Nanoparticles with bee venom can prevent HIV infection

­HIV is one of the greatest killers worldwide. Responsible for 1.7 million deaths worldwide in 2011, the virus causes the immune system to be weakened, leaving the body vulnerable to attack. The main reason that HIV is so deadly is that there is no cure for it, only treatments that can possibly extend the life of someone who is infected. This makes it crucial for people to stop the infection before it reaches them, something that could be made much easier with nanomedicine.

Researchers at Washington University School of Medicine in St. Louis are in the process of developing a drug that can not only kill off the HIV virus before one becomes infected, but can be able to kill of the virus when injected intravenously. The drug is not typical—it uses bee venom inside nanoparticles smaller than the virus, to kill it. The key component of bee venom inside the nanoparticle is melittin. Melittin is able to make small holes in cells, the HIV virus in this case, that will make it unable to harm the immune system.

The melittin has another effect, though, which is that it can fuse with the protective coating, called the viral envelope, that stays on the outside of the virus. This enables it to attack the virus and nothing else. The melittin-coated particle has shown to be harmless to all parts of the human body. With any type of virus removal in the human body there is always a worry that the virus will adapt, creating an even stronger virus that is more deadly than the original. This is a legitimate fear for much of the viral treatment that we use today, but is not a problem when attacking the viral envelope. Because the viral envelope is such an integral part of a virus, HIV is unable to adapt and remove it, which is the only way it could defend itself against milittin.

This nanoparticle seems like a very effective solution to HIV, but how will it be used? The first potential use for the nanoparticle is for it to be implemented into a vaginal gel. This gel could be used to simply prevent one partner from being effected with HIV, but could also work as a contraceptive and target sperm as well, or in place of HIV. There are many cases of couples where one partner is infected with HIV and the other isn't, but they want to have kids. The gel would kill off the HIV and the sperm would remain safe, allowing the children and mother to remain safe from the infection. Intravenous injection could be another use of this nanoparticle. When injected intravenously it would be able to kill all the HIV in one's blood, making the person much more healthy and possibly curing them at a young age.

This type of nanoparticle has potential to remove other types of diseases from the body as well. Viruses like hepatitis B and C have the same type of viral envelope as HIV, so they could be cured through intravenous methods using the same nanoparticle. Since the nanoparticle will be cheap to produce, it has the potential to be accessible where solutions to HIV carries the greatest burden, in developing countries.

http://www.nanowerk.com/news2/newsid=29425.php

http://www.who.int/gho/hiv/epidemic_status/deaths/en/index.html

http://www.huffingtonpost.com/2013/03/09/bee-venom-kills-hiv-cells_n_2843743.html

Carbon nanofibers grow back brain cells of stroke victims

Ischemic Stroke

Stroke is the second most common cause of death, causing 4.4 million deaths each year. A stroke severely damages the brain and destroys nerves and neural connections. The current treatment for strokes involves pieces of metal and silicon, which are very impractical to use in environments such as the brain. Carbon nanofibers have proven to be much more effective than metals at regenerating neural tissue.

Carbon nanofibers are made from cones of rolled graphene stacked on top of each other. They are conductive, non-toxic, and are accepted easily by cells in the body. This makes them the perfect tool for repair in damaged parts of the brain and other parts of the nervous system when incorporated into composites.

To heal damaged brain or spinal cord tissue, a neural prosthesis containing a small high conductivity electrode must be implanted into the damaged tissue. The electrode is used to stimulate and monitor the tissue. Electrodes have been traditionally made from metal silicon and alloys. Metal does not integrate well with the body, and the brain is no exception. Glial scar tissue forms densely around the metal causing it to conduct electricity less efficiently, and it also prevents the electrode from stimulating nerves for nerve regeneration. Carbon nanofibers (CNFs) are the perfect alternative to silicon for use in place of electrodes for nervous tissue regeneration.

CNFs have modifiable properties through changing the weight ratio of CNFs in the composite. Glial scar tissue, although less of a problem when encountered with PCU, is still able to form and prevent it from functioning. By increasing the surface energy of the CNF, astrocyte, one of the cells that forms scar tissue, is unable to form on the PCU composite.

By modifying the weight ratios of CNF in the composite from 2% to 25%, the electrical resistivity of the compound can be reduced. This could be used in a neural probe that contains different weight ratios of CNF in each part of it, creating different conductivities throughout the probe. Optimal neural growth and regeneration can also be found by changing the weight ratio of CNF in the PCU composites. This is achieved by the neurite extension of the neurons on the CNF.

Stem cells can differentiate into different types of cells, including neurons. Stem cells are used to treat many neurological disorders by regenerating damaged nerves. Through inserting stem cells into CNFs, the cells can be easily distributed throughout the brain and can quicken the regeneration of nerves. When hydrophobic or hydrophilic CNFs are injected into the brains of rats effected with a stroke, the rats regained motor function within three weeks and there was little scar tissue left afterward. CNFs containing stem cells would likely have the same result in humans.

Carbon nanofibers are the perfect tools for repairing the nervous system, especially the brain. Their ability to incorporate themselves into composites and their highly modifiable nature is what makes them so much better than metals. They are just one example of what nanotechnology can do for medicine, and there are many more applications of carbon nanofibers and nanotubes that will be discovered in the future.

Citations:
PubMed Health
Phong A. Tran, Ligie Zhang, Thomas J. Webster “Advanced Drug Delivery Reviews.”  (2009)

I would like to thank Dr. Sujata Bhatia (Biomedical Engineering Program, Harvard School of Engineering and Applied Sciences) for her guidance during the preparation of this blog.

Nanoparticles reduce negative effects of chemotherapy

Nanotechnology is predicted to be a US$ 3 trillion industry by 2020. One of the growing and most useful applications of nanotechnology is nanomedicine. An example of nanomedicine is a nanoparticle designed by researchers at the University of South Wales in Australia to lessen the need for chemotherapy in users with neuroblastoma.

Neuroblastoma is a form of childhood cancer that in most cases spreads throughout the body before it is detected. It occurs in one of every 100,000 children. Neuroblastoma is worse than many other cancers because it requires large amounts of chemotherapy to cure. Chemotherapy can be very dangerous to the patients that it is used on because of its side effects. Unpleasant side effects such as nausea, vomiting, easy bruising, loss of appetite, fatigue, and fever make the treatment painful, but long term side effects such as nerve damage, kidney and heart problems, damage to lung tissue, infertility, and risk of a second cancer make chemotherapy dangerous to a patient’s permanent health. Specially designed nanoparticles have the ability to cut the amount of chemotherapy needed for the patient to one fifth the original amount.

The nitric oxide injecting nanoparticles do not replace chemotherapy, but they reduce the amount needed to treat the cancer. In the past, the combination between nitric oxide and chemotherapy drugs was used but the method used to distribute the nitric oxide to cancer cells were unstable and toxic. The new drug has a shelf life of over two weeks and completely harmless. The main challenge in developing it was that the nanoparticles could trigger reactions in healthy parts of the body, but the researchers overcame this obstacle. The drug currently reduces the need for chemotherapy to one fifth the original amount, greatly reducing the harmful side effects that a patient could encounter.

This new drug is an example of how nanomedicine is opening doors for cancer and other medical treatment. Dr. Cyrille Boyer, who worked on the development of the drug, says "If we can restore nitric oxide with these nanoparticles this could have implications for all the illnesses associated with nitric oxide deficiencies, including diabetes and neurodegenerative." This nanoparticle and variants of it could have many more applications in the future. Nanotechnology is already having great impacts in medicine even though it is a new field. It is also one of the fastest growing fields, and will have even greater impact in other areas of medicine.

Batteries recharge 30 times faster using nanotechnology

As climate change threatens the stability of our planet, lessening our dependence on fossil fuels to reduce greenhouse gas emissions becomes increasingly important. In addition to concerns over climate change, analysts predict long-term uncertainty over oil supplies. Oil will become much more scarce over the next few decades, and the Institution of Mechanical Engineers predicts that oil production will be down to 20% of what it is now by 2040.

Because of this, there will not be enough petroleum-based vehicle fuels for cars. The auto industry is preparing for this by investing in electric cars, such as the Nissan Leaf, the Chevy Volt, the Ford Focus EV, and many more. Electric cars provide a viable solution to this problem, but one reason many people do not want to purchase one is because of how long they take to charge--a minimum of 3.5 hours for the Tesla Roadster electric sports car, up to 8 hours for cars like the Nissan Leaf.

Researchers at South Korea’s Ulsan National Institute of Science and Technology Interdisciplinary School and LG Chem, a leading supplier of lithium-ion batteries in the country, may have come up with a solution to this problem. The new new batteries charge 30 times faster than conventional batteries and have the potential to charge 120 times faster with further development. This could let people driving electric cars recharge in the same time it takes to fill a tank of gas in a gasoline powered car.

In conventional lithium-ion batteries, powdered nanoparticles are layered to create a dense structure that can store and give off energy. The new battery design will be in the form of a solution that contains carbonized graphite, forming a dense network connecting the electrodes of the battery. This will allow all the electrodes in the battery to charge at the same time, whereas current lithium-ion batteries can only charge from the outside in.

For the auto industry, this new battery technology could give electric cars the functionality they need to bridge the gap between energy efficiency and functionality. The only thing lacking in making electric cars competitive with conventional cars is infrastructure. Without common places to recharge, like gas stations, drivers will still have problems completing longer trips. Faster charging times for electric cars will make it easier for gas stations to add the ability to recharge them because they will only take minutes, not hours to charge.

These new batteries can also have an impact outside the auto industry. They would be extremely useful in electronic devices like mobile phones or in anything that needs to recharge, and they could increase the popularity of rechargeable standard batteries such as AA and AAA because they will recharge extremely fast.

Overall, these new batteries have the potential to make a massive impact on how we use batteries. Almost everyone uses something with a battery daily, and an increase recharge speed 30 fold can make a massive difference in both everyday life and the world around us.

Sources:
ens-newswire.com
www.zdnet.com
www.4evriders.org
www.imeche.org
Image:
www.globalmotors.net

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Solar paint to provide cheap electricity

With global warming becoming an increasing threat to our civilization’s stability, cheap, low-carbon energy sources are necessary to meet rising electric power needs.  Addition of solar panels to homes has the potential to take a load off the grid and power homes that are off it, but the high cost of solar panels is driving people away from using them.  The solution to this problem comes in the form of a paint.

With new “paint-on” solar cells, the next coat of paint that you add to your house could generate electricity.  At the University of Notre Dame’s Center for Nano Science and Technology (NDnano), researchers have created a “solar paint” that uses semiconducting nanoparticles to convert sunlight to energy. This research was funded by the Department of Energy's Office of Basic Energy Sciences.

The paint uses quantum dots, a type of nanoparticle that can produce energy.  These quantum dots were added to nanoparticles of titanium dioxide coated in cadmium sulfide or cadmium selenide. The mixture was suspended in a mix of water and alcohol creating an inexpensive solar paint that can be applied to any conductive surface using traditional painting methods.

Researchers at the University of Toronto and King Abdullah University of Science and Technology in Saudi Arabia achieved the best light-to-energy conversion efficiency reached so far; 7 percent, not far behind the 10 to 15 percent efficiency of commercial silicon solar cells.  Despite the lower efficiency, the reason this paint can make a difference is because of its low cost.  It can be used in mass quantities and will be accessible to people who are less wealthy.

Solar paint has the potential to give everyone access to solar power to slow the effect of global warming.  It can also give cheap power to people in developing countries who have abundant sun but limited access to electricity.  The global solar industry is expected to grow 15.3% by 2015 according to TechNavio’s report “Global Solar Panels Market 2011-2015,”  and it will grow even more if technologies like solar paint become widely used.


Citations:
http://www.sciencedaily.com/releases/2011/12/111221211324.htm, http://www.cleanenergyauthority.com/solar-energy-news/report-solar-growth-rate-through-2015-082512
http://www.laserfocusworld.com/articles/2012/08/cqd-solar-7-percent-u-of-t.html

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