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Toys, refrigerators, washing machines, socks—more and more products contain silver nanoparticles. It’s no wonder: These particles, which measure less 100 nanometers (smaller than a single HIV virus), can kill microbes on contact. But, researcher Darin Furgeson says, nanosilver can also escape into ecosystems and cause serious damage to fish embryos. Furgeson’s team published its results in the journal Small.

In one new experiment, Furgeson, a professor of pharmaceutical sciences, exposed zebrafish embryos to silver nanoparticles in a laboratory, and found that some died and others were left with dramatic mutations. “Some of the fish became extremely distorted, almost making a number nine or a comma instead of a linear fish,” he said [Scientific American]. Eyes, tails, and other body parts turned out malformed in the fish that survived.

Just how much nanosilver gets into the environment? A separate study from Environmental Science & Technology washed nine kinds of nanosilver-containing textiles, including some “anti-bacterial and anti-odor socks” that are already on the market. The researchers found that anywhere from less than 1 percent to as high as 45 percent of the silver came out in the first wash. Most of the silver was in the form of coarse particles of greater than 450 nanometers, suggesting that mechanical stress in the washing machine was responsible for most of the release [The New York Times], and that the nanoparticles might have aggregated to reach that size.

Those nanoparticles flushed out by a washing machine can end up in both fish habitats and drinking water supplies. Furgeson says his fish experiments could help show whether nanosilver is a health concern for humans, too. “Zebrafish have similar tissues and organs to us,” Furgeson said. “They don’t have lungs, but they do have a liver, kidneys and heart – though it is only two chambered – and they have a blood-brain barrier” [Scientific American].

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Image: Wiki Commons / Kristof vt

Contact lenses provide a number of convenience advantages over glasses, but one they come up short in one area—you can’t get contacts that automatically adjust to the sun’s UV light and darken, like the photochromic lenses many bespectacled people enjoy. But that could soon change: Researchers in Singapore led by Jackie Ying have now created a contact lens that responds to UV light.

Transition lenses for glasses are coated with a dye that is transparent when out of the sun, but responds to UV light by changing shape and darkening. Few previous attempts have been made to design transition contact lenses, largely because it’s difficult to apply dye coatings uniformly to the delicate, soft surface of a contact lens. Ying and her colleagues got around this by developing a contact lens that embeds dyes uniformly throughout the material [Technology Review].

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“Nanoparticles can cause DNA damage across a cellular barrier.” That’s the title of a paper published in Nature Nanotechnology that inspired a number of ominous news headlines (two examples: Nanoparticles ‘can damage DNA‘ and Nanoparticles can damage DNA at a distance: study). The stories that followed basically sang the same tune—that nanoparticles can damage our cells’ genetic material even from a distance (a relatively short distance of four cells away). However, experts are speaking up in response to the media hype, and argue that this study should have never been covered in the news. This particular study has little relevance to human exposure risks, experts say, and it is deeply flawed in other ways [ScienceNOW Daily News]. At least one expert called the study “meaningless,” however other scientists were more diplomatic and have pointed to a number of interesting questions the study raises that are worth pursuing.

In the study, researchers exposed a thin “barrier” of four layers of cancer cells to cobalt-chromium ions or particles. Cells close to the nanoparticles experienced signs of mitochondrial damage. But even cells on the other side of the barrier suffered some DNA damage, the team found, despite the fact that there was no evidence that the metals themselves moved through the cells to the other side of the barrier [ScienceNOW Daily News]. Interesting indeed, but experts are pointing out that this set-up is not entirely relevant to humans, or any living organism for that matter.

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Cancer treatment in the future could have dramatically reduced side effects if new nanotechnology research proves useful. Heat-sensitive nanoparticles might be able to deliver drugs to a targeted location in the body—to a tumor, say—and release them on cue, a sought-after goal of biomedical research.

One research team has developed nanoparticle cages that can be stuffed with tiny amounts of drugs that are only released on demand. These “nanocages” are cubes of gold, with sides about 50-billionths of a meter long and holes at each corner. They are easily made, using silver particles as a mold, and then coated with strands of a smart polymer. The polymer strands are normally extended and bushy and cover the holes in the cube. But when heated the strands collapse, leaving the holes open and allowing the drug inside to escape [The New York Times]. The researchers say they can engineer the nanocages to stick to tumors.

Doctors could release the packaged drugs whenever they want, just by zapping the cages inside the patient’s body with near-infrared light. Near-infrared wavelengths are not greatly absorbed by body tissues, so light from a near-infrared laser could penetrate a couple of inches inside the body, but they are absorbed by gold [The New York Times]. Researchers could design the cages to fall apart at just a few degrees above normal body temperature, so they only spill their contents where the heat is applied; they could also alter the drug’s rate of release by adjusting the laser’s intensity. The technology, described in the journal Nature Materials, could help cut down on the side effects of today’s treatments which are often caused by toxic drugs coursing through the body.

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Image: Younan Xia, Washington University in St. Louis

A new study may have hit upon another way to improve stem cells‘ ability to help repair damaged tissue. While stem cells can rapidly grow into any kind of new tissue, they aren’t always able to encourage new blood vessels to grow so that the tissue stays alive. But in a new study, published in the Proceedings of the National Academy of Sciences, scientists describe a way around the problem. The researchers used nanoparticles to ferry a key gene into the stem cells, which caused the cells to recruit new blood vessels, thus fueling tissue growth.

The nanoparticles carried a gene (VEGF) that is known to stimulate new blood vessel growth. When the modified cells were injected into mice whose hind limbs had been injured, the tissue that regrew to repair the damage had three times the blood vessel density of similar tissue in mice given unmodified cells. Four weeks later, only 20 per cent of the mice given modified cells had lost limbs, compared with 60 per cent in mice that received unmodified cells [New Scientist].

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Scientists have used nanotechnology in some bizarre applications—nanotube speakers and glue are just two examples. Now carbon nanotubes may have a use as fertilizer, according to a new study. Plant biologist Mariya Khodakovskaya and nanotechnologist Alexandru Biris … planted tomato seeds in a growth medium that contained carbon nanotubes. They found that the seeds germinated sooner and seedlings grew faster than those in a non-treated medium [New Scientist]. After 12 days, 72 percent of the treated seeds had germinated compared with 30 percent of the untreated group. After four weeks, the nanotube-supplemented seeds were twice as tall and had twice the biomass. However, the root systems in both groups were roughly the same.

Similar findings have been reported previously, but until now nobody understood how nanotubes sped and enhanced plant growth. The new study, which recently appeared in the journal ACS Nano, proposes that nanotubes poke holes in the seeds, which allows water to seep in and speeds up germination. However, some researchers are skeptical that a complex process like germination can be enhanced simply by poking holes in the seed’s coating, and at least one researcher is suggesting that the nanotubes cause a hormonal imbalance in the plants.

Before nanotubes could become a commercial fertilizer, their effect on the environment would have to be studied, with close attention to how nanotubes move through the food chain. Some single-walled nanotubes are toxic to some insects; testing on mice has found multi-layer nanotubes (like the kind used in the study) have carcinogenic effects similar to those of asbestos [Popular Science].

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Image: flickr / wit

In a doctor’s office in the near future, part of a smoker’s routine checkup could involve blowing into a tube connected to a small sensor. The doctor will look at the sensor’s display and know immediately whether she has to deliver the grim diagnosis: lung cancer. Researchers in Israel have invented a new “breathalyzer” that can detect chemical compounds produced by lung cancer cells. The finished device should be portable and inexpensive and provide a faster, easier, and more sensitive way to screen for tumours than X-rays or blood tests. Such screening should help doctors detect cancer early, when it’s most treatable [Telegraph].

The new device, described in Nature Nanotechnology, is not the first to find evidence of cancer on a person’s breath. Other attempts to do this have yielded promising results, … but those devices require a higher concentration of the telltale biomarker chemicals than the Israeli device. The chemicals, called volatile organic compounds (VOCs), are metabolic products present in the vapors that we breathe out, but they occur in such small amounts that researchers have had to find ways to increase their concentrations before testing [Technology Review]. But the new sensor has such sensitivity that it can detect traces of the compound in their natural concentrations in human breath, and it can therefore give results immediately, without processing and analyzing the sample in a lab.

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In the first known case that appears to link nanoparticles to health problems in humans, seven women fell ill after working with paint containing the particles at a factory in China, and two later died, according to an article in the European Respiratory Journal. However, some other experts debate the paper’s conclusions, saying that more mundane toxic materials are to blame.

The women developed itchy eruptions on their arms and faces, along with breathing problems, after working without proper protection at a factory producing paint that contains nanoparticles, which can be as tiny as one-billionth of a meter, or one nanometer. The women were all found to have ball-like collections of immune cells in the lining of the lung that form when the immune system is unable to remove a foreign body. They also had excessive, discoloured fluid in the lung lining. Particles around 30 nanometres in diameter were found in lung fluid and tissue [Nature News]. Sporadically used cotton gauze masks were the only protection the women wore during the five to 13 months they worked spraying paint on polystyrene boards in an unventilated room, and it’s likely they breathed in smoke and fumes. Once the factory was closed, no additional workers fell ill.

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The next big leap in computing power may come from a surprising source: the genetic code. Researchers at IBM have found a way to use DNA strands as the scaffolding on which to place carbon nanotubes, creating tiny microchips that could eventually be more efficient and cheaper to produce than today’s silicon chips. To keep pace with Moore’s Law, which postulates that the number of transistors on an integrated circuit will double every two years, chip makers have to squeeze an increasing number of transistors onto every chip [Wired.com]. The new process offers an entirely different route to miniaturization.

Microchips are used in computers, cell phones and other electronic devices…. Right now, the tinier the chip, the more expensive the equipment. [An IBM spokesman] said that if the DNA origami process scales to production-level, manufacturers could trade hundreds of millions of dollars in complex tools for less than a million dollars of polymers, DNA solutions, and heating implements [Reuters].

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A new optical storage technique that records in five dimensions could hold up to 10,000 times what a standard DVD can store. The new technology could see a whopping 1.6 terabytes of information fit on a DVD-sized disc [BBC], whereas a DVD now can hold only 8.5 gigabytes and a Blu-ray disc up to 50.

Discs started out storing information in two dimensions and more recently have been stepped up to three. By using gold nanorods [the researchers] were able to add two additional dimensions, one based on the colour spectrum, and the other on polarisation [PhysOrg]. The key for his team was to find a material for the disk that could store this extra information…. That ideal material contains gold, rod-shaped nanoparticles of different sizes and orientations [Nature].

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Would you like to wear your Facebook profile on the sleeve of your T-shirt? Or maybe the artists Christo and Jeanne-Claude would like to wrap a building in computer screens? Such marvels may one day be possible due to a stretchy display researchers created by connecting organic light-emitting diodes to a new rubbery conductor. Researchers say the display is remarkably durable–they bent it, folded it in half, and even crumpled it up without affecting its performance. What’s more, the display, which is thinner and less power-hungry than equivalent plasma and LCD screens, is produced through a cheap industrial printing process [Fast Company].

Organic light-emitting diodes (OLEDs) are not yet familiar technology, but many researchers think they’ll play an important part in the next generation of electronics. The organic compounds in an OLED system emit light when an electric current is passed through them and need no backlight, which means they draw less power and can be thinner than a typical liquid crystal display (LCD) screen. But the real breakthrough in the current research is in the stretchy conductor underlying the OLEDs.

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In a masterful work of “DNA origami,” researchers have created a nanoscale DNA “box” which can be opened with DNA “keys”. One day, such structures could be filled with drugs, injected into the blood, and then unlocked when and where the drugs are required [New Scientist]. Researchers say the boxes could also be used as minuscule environmental sensors that open or close in response to a stimulus, or as the logic gates of a DNA-based computer.

To accomplish this feat, described in a paper in Nature, researchers exploited the fact that complementary DNA bases–the fundamental building blocks of DNA’s double helix–attach to each other. To design the box, the researchers developed a computer program to generate a continuous single-stranded DNA sequence that, along with smaller DNA fragments that act as staples, would self-assemble into the desired shape. The sequence was devised with many complementary regions so that it would automatically fold into six roughly square accordion-like sheets–the sides of the box–based on DNA’s natural tendency to pair into double strands. The DNA staples, also driven by the pairing of complementary sequences, stitched the sheets’ edges together to form a hollow cube with a hinged lid [Technology Review]. The final product was a box that measured 42 by 36 by 36 nanometers, and had a cavity big enough to hold enzymes or virus particles.

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Two groups of researchers have found ways to “unzip” carbon nanotubes to make nanoribbons of graphene, and experts say the development could point the way towards a new generation of electronics, including computer chips that are faster and tinier than the silicon-based chips used today.

Graphene, an atom-thick sheet of honeycombed carbon, is one of the hottest materials around. It conducts electrons well, but is thin, transparent and strong, making it potentially useful in displays and solar panels. Ribbons of graphene could be more useful still. At widths of around 10 nanometres or less, electrons are forced to move lengthwise, and make the graphene behave as a semiconductor [Nature News].

However, the ribbons have proved extremely difficult to produce. Previously, nanoribbons of graphene [were] cut from larger sheets using chemical methods that, like a blunt pair of scissors, offer little control over the width of the ribbons [New Scientist].

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The latest advance in battery technology comes from viruses working on the nanoscale. Researchers have constructed a lithium-ion battery, similar to those used in millions of devices, but one which uses genetically engineered viruses to create the negatively charged anode and positively charged cathode [BBC News]. The tiny workers are bacteriophages, viruses that infect bacteria but are harmless to humans.

Three years ago, the same researchers created viruses that collected negatively charged particles of cobalt oxide and gold, which “grew” on a film to create the anode. Now, the researchers have added to that achievement, tackling the trickier task of making cathodes. The work was more difficult because the material had to be highly conductive in order to be effective and most candidate materials for cathodes are highly insulating [BBC News]. The researchers engineered viruses that coat themselves with iron phosphate. Then they then latch onto carbon nanotubes to create a network of highly conductive material [ComputerWorld]. Iron phosphate is generally not a good conductor, but its properties change when it’s organized on the nanoscale.

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The mechanical energy produced when your body moves could be harnessed to power electronic gadgets thanks to what researchers are calling a “nanogenerator.” The nanotech device is made of tiny zinc oxide nanowires, which have piezoelectric properties–meaning that they generate a tiny electrical pulse when they’re bent, stretched, or otherwise subjected to mechanical stress. According to Zhong Lin Wang, lead researcher, the device could be used to charge gadgets such as iPods and BlackBerrys as well as having a impact on defence technology, environmental monitoring and biomedical sciences. “This technology can be used to generate energy under any circumstances as long as there is movement,” he said [Financial Times].

In a video demonstration, Wang attached a single nanowire to the back of a hamster and then hooked it up to an oscilloscope. As the rodent … scurried around, it generated 70 millivolts [the equivalent of .o7 volts]. When the critter stopped to lick itself, the power levels decreased [Wired].

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