NEWS : TECH (NFPC)

Lens Converts Light Into Sound

By Dexter Johnson, IEEE Spectrum

The researcher used sound waves to drill holes into a confetti-sized artificial kidney stone. Credit: Jay Gou, University of Michigan

Remember how Leonard McCoy performed surgery in Star Trek? He would wave a device over the patient. The outer layers of the skin didn't need not be cut, even when operating on internal organs, and the precision of 23rd-century instrument reached down to the level of individual cells.

Well, we already have a bit of that in the 21st. Research at the University of Michigan, led by Jay Gou, has developed a device that employs a carbon-nanotube-coated lens capable of converting light into tightly focused sound waves. The new ultrasound therapeutic tool that reaches new levels of precision -- its high-amplitude sound waves are able to target an object with dimensions of 75 by 400 micrometers.

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"A major drawback of current strongly focused ultrasound technology is a bulky focal spot, which is on the order of several millimeters," says Hyoung Won Baac, who worked on the project as a doctoral student and is now a research fellow at Harvard Medical School, in a press release. "A few centimeters is typical. Therefore, it can be difficult to treat tissue objects in a high-precision manner, for targeting delicate vasculature, thin tissue layer and cellular texture. We can enhance the focal accuracy 100-fold."

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The research, which was published in the journal Nature (“Carbon-Nanotube Optoacoustic Lens for Focused Ultrasound Generation and High-Precision Targeted Therapy”), coated a concave lens with a nano-composite film of carbon nanotubes (CNTs) and elastomeric polymer. A pulsed laser source is aimed at the lens. The CNTs absorb the light coming from the laser which generates heat. The polymer expands from the heat being generated by the CNTs. This rapid expansion of the polymer amplifies the signal.

The CNT-coated lens when coupled with a pulsed laser is capable of extreme optoacoustic pressures of >50 megapascals. This unprecedented level of pressure results in both shock effects and cavitation without heat being used on the target.

While recent research in sharpening sound waves -- at least for imaging devices -- has led to exotic acoustic hyperlenses made from metamaterials, the underlying technique behind this device’s conversion of light to sound goes back to at least Thomas Edison. But to date the sound projected from devices employing these techniques was not strong enough to prove useful in medical applications.

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"We believe this could be used as an invisible knife for noninvasive surgery," Guo says in a university press release. "Nothing pokes into your body, just the ultrasound beam. And it is so tightly focused, you can disrupt individual cells."

It may still be a while before your surgeon is able to wave a wand over you and send you back to your hospital room without a scar -- the technology hasn't even been tested on animals yet -- but we may get there well before the 23rd century.

This article originally appeared on IEEE Spectrum as Nanoparticle Coated Lens Converts Light into Sound for Precise Non-invasive Surgery

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Nanoscience Explained: Gotta-See Video

Nanoscience is small science with huge possibility. "Nano-" is a prefix that means "a billionth." Basically just recognize that when we talk about nanoparticles, nanobots, nanoscience, nanotubes or nanotech, this stuff is REALLY tiny.

Nanoscience has been around a while, but people aren't necessarily aware of what research and applications are being explored. Take a quick tour of nanoscience here and learn enough to make a few declarative statements at your next cocktail party. via YouTube

Want to recommend a video? Tweet it to @Discovery_News with the hashtag #GottaSeeVideos.

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Nanobot Could Cure Diseases: DNews Nuggets

Nanorobot Targets Viral Infections: At the University of Florida a new breakthrough offers a cure for those infected with Hepatitis C, a nanorobot.

The robot is constructed to seek out the Hepatitis C virus and kill it, without engaging the human bodies natural defenses. Currently, the treatment can destroy the human body, but this nanobot may not only level the field, but tip it toward our science.

Theoretically, the nanobot can be configured to target cancer, and other viruses as well. Further testing is needed before it will be released to the public, but it's a promising start. via Gizmag

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Nanocomposite Can Reverse Cavities

Dental fillings replace the part of the tooth drilled out in order to remove decay. But if any bacteria remains, the cavity can grow right under the filling.

A new composite material, made up of silver and calcium nanoparticles, could work as a dental filling that kills remaining bacteria, so that patients don't have to make a return trip to the dentist. The material, developed by researchers at the University of Maryland, also rebuilds any structure affected by decay -- essentially getting rid of the cavity altogether.

Because of their small size, the silver nanoparticles can invade the cellular structure of bacteria and other microorganisms and kill them. Calcium phosphate, also included in the composite, is responsible for building the tooth back up.

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There have been questions raised about implementing these materials into toothpaste or mouthwash, but the scientific community isn’t ready to get onboard with that idea just yet. There is a lot of concern coming from scientists and researchers about the possible harmful effects of human consumption of the particles. Further testing will be conducted on volunteers to sort through the health concerns.

Credit: Manchan / Getty Images

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Diamond Coating Improves Artificial Joints

More than 746,000 Americans have knees or hips replaced every year. But the joints, made of metal and polymer, aren't a permanent solution because everyday wear and tear grinds off tiny bits that cause inflammation. That isn't all: the inflamed areas cause cells near the implants to actually eat away at the bone itself.

Coating the joints with a nanometer-thick layer of diamond could change that, not only lengthening the useful life of a replacement (which is currently about a decade or so) but also reducing the inflammation.

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The inflammation comes from cells in the body called macrophages. These cells eat the metal that gets worn off artificial joints and releases chemicals that cause pain, swelling and bone damage.

A study at the University of Alabamaat Birmingham, led by Vinoy Thomas, has shown that at least in the lab, the macrophages that absorb metal debris will do the same for the tiny bits of diamond, but with less inflammation.

The key seems to be the concentration, rather than the particle size. The cells were exposed to nanodiamonds of varying sizes and concentrations. At less than 50 micrograms per milliliter of solution -- the typical debris in a joint -- the particles weren't toxic. The macrophages thrived even in the presence of the largest pieces, which were 500 nanometers across. When the concentrations topped 200 micrograms per milliliter, the cells' vitality was reduced.

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The experiment was done with macrophages in a dish, so it is unclear what would happen inside the body. The next step is looking at where nanodiamond particles would accumulate, experiments with mice showed they tend to gather in the liver, spleen and lungs with no ill effects. But mice are not humans and they weren't given joint replacements. 

Still, if this works joint replacements will be a lot less frequent, and the new joints a lot less painful.

Image: University of Alabama at Birmingham

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Bubbles Propel Microrockets Through Acid

Micromotors could give "the runs" a different meaning. Researchers just designed tiny micromotors that propel themselves through acidic environments using hydrogen bubbles. That means they can work in stomach acid.

The research group, led by University of California San Diego nanoengineering professor Joseph Wang, constructed each micromotor from extremely tiny plastic tubes containing a thin layer of zinc. The structure measures nearly 10 micrometers in length. When the engineers put the little rocket in an acidic solution, the zinc lost electrons, creating hydrogen bubbles. Then, zoom.

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As the pH in the solution decreases, the rocket's speed increases. Wang and his colleagues say their micromotor can travel up to 1,050 micrometers per second, which is about 100 body lengths per second. That seems fast to me.

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Although they sound a bit like Alka-Seltzer tablets, the researchers were able to control the rocket's by adding magnetic layers to the outer structure. Through manipulation of the magnetic field, the rockets could even pick up and release tiny plastic "cargo." PhysOrg embedded a couple of videos showing the micromotor in action that look like M.C. Escher drawings.

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The researchers' work was recently published (abstract) in the Journal of the American Chemistry Society. Apparently this was the first time a micromotor has been built that didn't require extra chemical fuel. 

The researchers say they think these devices could have a bunch of biomedical and even industrial applications. Imagine putting one in your stomach to do some reconnaissance. Next, Wang has indicated that the next step is to extend the micromotor's lifetime. Much like effervescent tablets, it stops bubbling after a couple minutes.

Image: The circle highlights a microscale rocket transporting tiny plastic cargo, captured in a time-lapse video. Credit: Wei Gao, et al. and the American Chemical Society.

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Fluorescent Nanotubes Image Internal Organs

When conducting drug testing on laboratory mice, it's often useful to image the internal organs of the animals in detail. While there are accurate methods such as MRI or CT scans, the associated cost and complexity of these systems is not a very efficient solution. A cheaper and simpler technique involves injecting the animals with fluorescent dyes that are diffused into the blood stream and channeled to the internal organs.

The drawback of traditional fluorescent dyes is that the images generated are only useful at a depth of a few millimeters. Anything deeper and the reflection from the dyes causes the images to appear foggy. The main reason for this limitation is that biological tissue has some natural fluorescent properties at the same wavelength as the dyes. In addition, the tissue has a tendency to scatter light at this frequency.

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This May, a team of scientists in Standford University, announced that they had created a dye composed of carbon nanotubes designed to fluoresce at that was different than the natural fluorescent properties of biological tissue. This greatly minimizes light scatter. They have been able to image the tissue of mice at a depth of several millimeters without the haziness and distortion that occurs with regular dyes.

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The team has previously used similar nanotubes as drug delivery system and they now expect that the imaging aspect of this technology can be added to the delivery systems for enhanced performance. Hongjie Dai, a professor of chemistry at Stanford explained in a university press release that "with the fluorescent nanotubes, we can do drug delivery and imaging simultaneously -- in real time -- to evaluate the accuracy of a drug in hitting its target."

[via Gizmag]

Credit: PNAS

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Fluorescent 'Tattoo' Monitors Chemicals in Blood

Don't let the name fool you -- the so-called “microworm” devices created by researchers at MIT and Northeastern for implant under the skin are not living creatures. Instead they are small tubes filled with particular chemicals that emit light in response to certain chemicals present in the blood. The light could warn diabetics or other people with blood conditions of a potential danger, such as low blood sugar, early on and prevent devastating side effects, like kidney failure or blindness.

Microworm tubes are so tiny -- less than one hundredth the width of a typical human hair -- that the body doesn't even react to their implanted presence beneath the skin (though the FDA might still have issues approving these novel devices without proof of their long-term safety). Once inside, they are visible to the human eye as a fluorescent “tattoo.” I wonder whether the patient has any say in it's design, although I bet one doesn't need a Mom-filled-heart's worth of nanotubes for the implant to be medically useful.

The tubes are manufactured in a process similar to shrink wrapping. A vaporized material is deposited onto the tubes, leaving a surface coating that makes pores on the surface smaller and able to react to other chemicals in the environment. Additionally, more reactive chemicals, or even drugs for delivery, can be inserted into the pores before they are capped at either end. The whole process is relatively cheap and easy to do, since this method of manufacture is already standard in the semiconductor industry.

So far, the team has only tested this technology as a device for monitoring salt levels in mice. But scientists are enthusiastic that this could be applied to other diseases like diabetes, and could one day be done right in the doctor's office. Is this getting trendy? I'm keeping a lookout for the first medical tattoo parlor.

Photo: A scanning electron microscope image of a bundle of microworms. MIT/Gleason Lab

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Nontoxic Nanotech Uses Cinnamon

A dash of spice makes everything nice, including nanotechnology. Scientists at the University of Missouri have a way to make gold nanoparticles using cinnamon instead of toxic chemicals.

Nanotech has all kinds of potential, including as a tool to fight cancer. Small particles -- ones that are much, much smaller than a human cell -- can do what chemicals can't. Gold, in combination with active chemicals, turns out to be ideal for targeted cancer treatment and detection. The problem is that making gold nanoparticles involves toxic chemicals.

A University of Missouri team led by radiology and physics professor Kattesh Katti developed a greener alternative. The researchers took cinnamon, mixed it with gold salts in water and successfully produced gold nanoparticles. Sounds kind of like alchemy at first glance, but the scientists found that cinnamon and other kinds of plants contain naturally occurring chemical compounds called phytochemicals.

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Here I was thinking the spice was great for mulled wine, when it turns out to be great at converting metals into nanoparticles. Katti told the university that their ecologically benign nanoparticles "are biologically active against cancer cells."

To study the cinnamon process, the team tested the nanoparticles on mice. They found that cancerous cells took up significant amounts of the nanoparticles, which were then detected with photoacoustic signals. The scientists published their findings in the journal Pharmaceutical Research (abstract) this fall, concluding that their nanoparticles "may provide a novel approach toward tumor detection through nanopharmaceuticals."

I've been as excited about nanotechnology as I have been wary of its potential detrimental effect on the environment. My concern is that we'll be creating more problems in the process of addressing the ones we already have. If Katti and his team can develop their plant-based nanoparticles into a viable option for cancer treatment and detection, they deserve a celebratory cake. A spicy one.

Photo: Cinnamon is the key ingredient for making gold nanoparticles nontoxically. Credit: S. Diddy.

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Messenger Bacteria Could 'Tweet' Directions to Nanobots

Okay, this one's a little complicated, but super cool. So, hang with me.

Doctors would really like to fight diseases such a cancer in precise, directed ways. That means delivering cancer-killing therapies to ugly cells, while leaving healthy cells alone. One way that could happen in the future is by using super tiny robots -- nanobots -- that work together inside the body like an infantry of warriors armed to battle cancer.

But there are some big challenges. Among them, communication. Like any battlefield army, soldiers need to coordinate their attacks. And nanobots, in theory, would have a difficult time. They can't use nano-sized cell phones, for example, because radio signals don't travel through liquids. (What about sonar? Has anyone looked into nano-sonar?) And chemical forms of communications are not appropriate for distances longer than a few micrometers.

So, a team from the Nanonetworking Center in Catalunya at the Technical University of Catalonia are looking at a way to use bacteria as messengers that deliver instructions to nanobots wrapped in DNA. Researchers Maria Gregori and Ignacio Llatser encoded the cytoplasm of non-pathogenic strain of E. coli with a short DNA sequence. Think of it as a tweet.

Here's how it might work: A scout-like nanobot in the body encounters a cancerous tumor. It wants to call over the troops for an attack, so it releases bacteria encoded with packets of information in the form of DNA. The bacteria swim towards soldier nanobots, where they attach to the nanobots and then download their DNA message. Orders in hand, the nanobots arm their attack.

It's way cool, but keep in mind this is all theory and simulation. In the simulation, bacteria equipped with flagella -- whip-like tails that propel them forward -- took about 6 minutes to travel 1 millimeter. And the amount of data they carried in DNA is equal to about 600 kilobits of information every 6 minutes, which is about 1.7 kilobits per second.

“This is much lower than the speed of 3G mobile connections, but it should still be enough for the biomedical applications that are envisaged for this scenario,” Llatser told Discovery News in an email correspondence.

Credit: iStockphoto

[via New Scientist]

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