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Posts Tagged ‘nanoparticles’

The sensor is what’s known as a “whispering gallery resonator” and relies on the same principles as those acoustic spaces (like the aforementioned Capitol and cathedral galleries) where whispers on one side of the room can be heard directly on the other side thanks to the unique properties of the shape of the space. But unlike the acoustic spaces (which are usually in round, domed spaces) that have audible sweet spots, the new sensor has optical sweet spots.

There’s a lot of optical science that goes into this, and we’re not going to get bogged down too deeply in it here (there’s plenty more science via the link below), but essentially it works thusly: A micro-laser beam no larger than a pinprick is generated in a small ring. When particles land on the microlaser it disturbs the frequency, and those changes in frequency can be measured to identify and count the number of particles present.

The sensor can tally up to 800 nanoparticles before the signals become too noisy to be accurate. It can even sense underwater. Or, ostensibly, in blood.

Near term, the new nanometer scale laser sensors--which the researchers claim are orders of magnitude more sensitive than previous passive resonators--will be deployed as environmental sensors capable of monitoring for chemical changes in air or water. But the team wants to engineer them to detect DNA and other biological molecules individually.

Specifically, researchers have developed nanoparticles that can guide each other to a destination, resulting in a much more effective onslaught against a tumor.

Nanoparticles could be a boon for cancer treatment because they can travel through the body unimpeded, delivering drugs directly into tumors and lessening the side effects of chemotherapy. But they quickly disperse when they’re released into the body — even in the best cases, only about 1 percent of them reach their intended target, according to MIT.

To improve this outcome, researchers from MIT, the Sanford-Burnham Medical Research Institute and the University of California-San Diego designed nanoparticles that can work in teams. One wave of nanoparticles homes in on a tumor, and when they arrive, they can communicate their location to the other nanoparticles still circulating in the body, helping them find the tumor too.

To do this, the nanoparticles take advantage of the body’s blood coagulation process, according to formal MIT doctoral student Geoffrey von Maltzahn, who is the lead author on a paper in Nature Materials describing this new work. At the site of an injury, blood clotting factors and other proteins interact in a chain of steps to form fibrin, which seals the wound and prevents further blood loss, as an MIT news release explains. The proteins not only bind to the area of an injury, but recruit other proteins to the area, von Maltzahn said.

“We’re trying to emulate that on the scale of synthetic particles, such that when one particle gets to the site of disease, it can communicate that event to expedite the subsequent arrival of other synthetic nanoparticles,” he explains in a video posted by MIT’s David H. Koch Institute for Integrative Cancer Research. (Watch it below.)

The researchers used two types of nanoparticles, which could either signal a message or receive it. The signaling particles flow through the bloodstream and arrive at the tumor site, where they trick the body into believing an injury has occurred (either by emitting heat or binding to certain proteins). This stimulates the natural fibrin-building process. Then the receiving nanoparticles, which carry a payload of cancer drugs, are outfitted with proteins that bind to fibrin. The fibrin acts as a homing beacon, helping the nanoparticles travel to the tumor site. They release the drugs once they get there, delivering a targeted blow to the cancer cells.

The researchers studied this method using mice and found that the communicating nanoparticles delivered 40 times more doxorubicin, a common chemotherapeutic, than a system that could not communicate.

MIT researchers are exploring how to test this system with existing clinical studies using nanoparticles.

MIT Tech TV

[MIT News]

Among the millions of tons of nanoparticles manufactured annually, silver nanoparticles are a particular favorite as they work as antibacterial agents in surgical tools, water treatment, wound dressings, and in a variety of other roles. They’ve even been used in the cathodes of batteries.

And, if this study is correct, they are wreaking absolute havoc on critical soil systems that make plant life possible.

The researchers had begun to wonder what the impact of nanoparticles were on the environment, and having received a chunk of Arctic soil as part of the International Polar Year they decided to experiment on this piece of uncontaminated earth. They first studied the sample to see what kind of microbe communities were living in the soil, and identified a certain beneficial and prevalent microbe that helps fix nitrogen to plants. Plants can’t do this on their own and nitrogen is critical to their growth, so this particular microbe is essential to plant life.

The researchers then added three different kinds of nanoparticles to the soil and let it sit for six months. When they re-examined it, they found that this microbe had largely been extinguished, and laboratory analysis showed that silver nanoparticles were the culprit. Given the high number of silver nanoparticles slipping into the environment on a daily basis, such findings are concerning.

It’s but a single study that needs to be thoroughly replicated of course, but if confirmed it certainly wouldn’t be the first time humanity has rushed an innovation into the marketplace only to regret it later. The findings were published today in the Journal of Hazardous Materials, so hopefully the right people will give the findings a closer look.

[Queen's University]

Bludgeoning bacteria instead of drugging it

The nanoparticles, which IBM says are relatively inexpensive, were effective against bugs that have been evolving to resist antibiotics, including methicillin-resistant Staphylococcus aureus (MRSA). Preliminary results suggest the particles could also be effective against yeast, fungus and small bacteria like E. coli, IBM says. Research on the new particles is reported in this week’s issue of the journal Nature Chemistry.

Antibiotics kill microorganisms in various ways, including interfering with their DNA or interacting with their ability to rebuild their cell walls, explains James Hedrick, advanced organic materials scientist and master inventor at IBM Almaden Research Center in San Jose, Calif. But some of the bugs survive the onslaught, leading to new generations of bacteria that won’t succumb to the drugs.

A new class of positively charged plastic micro-machines, including IBM's nanoparticles, take a somewhat more physical approach.

“These are designed to slice the cell membrane, to rip the membrane up and eliminate the contents,” Hedrick said. “It’s kind of like the way a virus would work — a virus drills a pore, empties the contents and hijacks it. This is drilling in little holes, and all the contents leak out.”

Transmission electron micrographs show it works: As the images show, the cell walls have been ruptured and everything inside is gone. The best part is that bacteria cannot evolve resistance because it's a physical attack, not a chemical one.

These particles are special because they self-assemble in water and are biodegradable, unlike other nanoparticle treatments. They’re made of amphiphilic polycarbonate material, meaning some of the particles are water-loving and some are water-phobic. When exposed to fluids — like serum or blood — the polycarbonate self-assembles into clumps about 200 nanometers in size. Another part of the clump is positively charged, designed to match the negatively charged surface of microbes, Hedrick said.

Cell walls are dynamic barriers, constantly morphing and changing as they divide. When something binds to their surface, the walls’ synthesis is interrupted. Penicillin, for instance, binds to an enzyme that helps build the walls. Hedrick and collaborators at the Institute of Bioengineering and Nanotechnology in Singapore say the charged particles interact with the cell walls to destabilize them.

“These particles are cationic (positively charged), so they are attracted to the microbial membrane surface, and it begins to disrupt that dynamic assembly process of the membrane,” Hedrick said.

The authors also report that the particles can be used at relatively low concentrations. Hedrick said they’re not sure what makes the particles so effective, but it’s probably because they can each kill multiple cells, moving on to new targets after the membranes are so disfigured that static no longer binds the cells and nanoparticles together.

“A little of the polymer goes a long way,” Hedrick said.

After a few days of this, enzymes start breaking apart the chains that hold the particles together, said Bob Allen, senior manager at IBM-Almaden’s Advanced Materials Chemistry department.

“Think of the enzyme as a pair of scissors — it will go through and snip it. It’s just a weak link that allows you to have a degradable system,” he said.

The particles degrade to molecules of alcohol and carbon dioxide, which are removed just like anything else in the bloodstream.

IBM believes the particles could be a new way to treat drug-resistant bacteria, especially MRSA, which is frequently associated with hospital infections. The company says antibiotic-resistant bacteria is a fertile field for its polymer research labs — chemists do focus primarily on electronics, but chip-scale research translates well to research in health care, water purification, and energy, Allen said.

Hedrick and Allen cautioned that they’re not clinicians and they don’t know how the particles would be used. But they were optimistic about the possibilities.

“The applications are going to be very diverse, whether we’re talking about wound healing or dressing, skin infection, and quite possibly injections into the bloodstream,” Hedrick said. “But this is way early in the discovery process to be going there.”

With their bright, continuous fluorescent glow that transitions between red, green and yellow, the nanoparticle is a better way to tag molecules, both in its function and in its good looks.

Earlier attempts to tag molecules with bright quantum dots were hindered by the dots' on-and-off blinking, like trying to follow a blinking flashlight through a dark room. The Ohio State engineers fixed the faulty flashlight. Led by assistant professor Jessica Winter and research scientist Gang Ruan, the team placed a group of quantum dots inside a slightly larger plastic nanoparticle. Whenever a single quantum dot within the nanoparticle blinked off, the team simply followed the glow of its neighbors.

The team used green and red quantum dots. Nanoparticles filled with red dots glow red, while those with green dots glow green. The almost magical color changes occur in the nanoparticles containing a mix of red dots and green dots. When a green dot blinks at the same time as a red dot neighbor, the light appears yellow to the eye. The quantum dot flashes mix together to become blobs of color that melt away as other colored blobs materialize, making the nanoparticle look like a miniature lava lamp.

Using the new technology, which the Ohio State research team is trying to patent, scientists could gain a better glimpse of biological processes at a cellular level.

[ScienceDaily]

With their bright, continuous fluorescent glow that transitions between red, green and yellow, the nanoparticle is a better way to tag molecules, both in its function and in its good looks.

Earlier attempts to tag molecules with bright quantum dots were hindered by the dots' on-and-off blinking, like trying to follow a blinking flashlight through a dark room. The Ohio State engineers fixed the faulty flashlight. Led by assistant professor Jessica Winter and research scientist Gang Ruan, the team placed a group of quantum dots inside a slightly larger plastic nanoparticle. Whenever a single quantum dot within the nanoparticle blinked off, the team simply followed the glow of its neighbors.

The team used green and red quantum dots. Nanoparticles filled with red dots glow red, while those with green dots glow green. The almost magical color changes occur in the nanoparticles containing a mix of red dots and green dots. When a green dot blinks at the same time as a red dot neighbor, the light appears yellow to the eye. The quantum dot flashes mix together to become blobs of color that melt away as other colored blobs materialize, making the nanoparticle look like a miniature lava lamp.

Using the new technology, which the Ohio State research team is trying to patent, scientists could gain a better glimpse of biological processes at a cellular level.

[ScienceDaily]

The method could illuminate how nanostructures work

Now a group of researchers in Europe have figured out a way to do it, and translate those pictures into colorful 3-D graphics that allow them to count individual atoms and see how they're arranged.

To take their nanopictures, Marta Rossell of ETH Zurich and Rolf Erni of the Swiss Federal Laboratories for Materials Science and Technology (EMPA) used a special electron microscope at Lawrence Berkeley National Laboratory. The machine has a resolution greater than the diameter of a single atom, allowing the researchers to zoom in on the nanoparticles’ atomic structures with great clarity.

They used silver nanoparticles in an aluminum matrix and tilted them under the electron beam to capture images. Then, Sandra Van Aert from the University of Antwerp built models based on those images, sharpening their resolution. Then Dutch tomography scientist Joost Batenburg used algorithms to reconstruct the silver nanoparticle in 3-D, detailing how all its 784 atoms were arranged.

“Up until now, only the rough outlines of nanoparticles could be illustrated using many images from different perspectives,” Rossell explains in an EMPA news release.

This sort of nanoparticle characterization could help determine which atomic configurations are best suited to various applications, like medical devices, drug transport systems and more. It could even illuminate how to use nanoparticles to mimic viruses or deliver vaccines. Incidentally, two separate teams announced breakthroughs on both those fronts today.

Emory University researchers announced Wednesday they had built tiny nanoparticles that resemble viruses in size and composition, and which induce lifelong immunity in mice. The particles are made of biodegradable polymers and activate two different parts of the innate immune system, the researchers say. They could be used with material from many different bacteria or viruses, a potential breakthrough for vaccine delivery.

Also in nanovax news, MIT researchers said Wednesday they had developed a new nanoparticle that can deliver safe vaccines for diseases like HIV and malaria. The particles, which are fatty spheres, can carry synthetic versions of virus proteins that elicit a strong immune response, according to MIT News.

Now that there’s a method to take their pictures, scientists may be able to learn even more about how nanoparticles function at the atomic scale.