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Safer nanoparticles spotlight tumors, deliver drugs
February 23, 2009Small is promising when it comes to illuminating tiny tumors or precisely delivering drugs, but many worry about the safety of nano-scale materials. Now a team of scientists has created miniscule flakes of silicon that glow brightly, last long enough to slowly release cancer drugs, then break down into harmless by-products.
"It is the first luminescent nanoparticle that was purposely designed to minimize toxic side effects," said Michael Sailor, a chemistry professor at the University of California, San Diego who led the study.
Many nanoparticles tested in research labs are too poisonous for use in humans.
"This new design meets a growing need for non-toxic alternatives that have a chance to make it into the clinic to treat human patients," Sailor said.
The particles inherently glow, a useful property that is most commonly achieved by including toxic organic chemicals or tiny structures called quantum dots, which can leave potentially harmful heavy metals in their wake.
When the researchers tested their safer nanoparticles in mice, they saw tumors glow for several hours, then dim as the particles broke down. Levels dropped noticeably in a week and were undetectable after four weeks, they report in Nature Materials February 22.
This is the first sudy to image tumors and organs using biodegradable silicon nanoparticles in live animals, the authors say.
The particles begin as thin wafers made porous with an electrical current then smashed to bits with ultrasound. Additional treatment alters the physical structure of the flakes to make them glow red when illuminated with ultraviolet light.
Luminescent particles can reveal tumors too tiny to detect by other means or allow a surgeon to be sure all of a cancerous growth has been removed.
These nanoparticles could also help deliver drugs safely, the researchers report. The cancer drug doxorubicin will stick to the pores and slowly escape as the silicon dissolves.
"The goal is to use the nanoparticles to chaperone the drug directly to the tumor, to release it into the tumor rather than other parts of the body," Sailor said.
Targeted delivery would allow doctors to use smaller doses of the drug. At doses high enough to be effective, when delivered to the whole body, doxorubicin often has toxic side effects.
At about 100 nanometers, these particles are bigger than many designed to deliver drugs, which can be just a few nanometers across - a thousand times smaller than the diameter of a human hair.
Their larger size contributes to both their effectiveness and their safety. Large particles can hold more of a drug. Yet they self-destruct, and the remnants can be filtered away by the kidneys.
Close examination of vulnerable organs like liver, spleen and kidney, which help to remove toxins, revealed no lasting changes in mice treated with the new nanoparticles.
University of California - San Diego
"This new design meets a growing need for non-toxic alternatives that have a chance to make it into the clinic to treat human patients," Sailor said.
The particles inherently glow, a useful property that is most commonly achieved by including toxic organic chemicals or tiny structures called quantum dots, which can leave potentially harmful heavy metals in their wake.
When the researchers tested their safer nanoparticles in mice, they saw tumors glow for several hours, then dim as the particles broke down. Levels dropped noticeably in a week and were undetectable after four weeks, they report in Nature Materials February 22.
This is the first sudy to image tumors and organs using biodegradable silicon nanoparticles in live animals, the authors say.
The particles begin as thin wafers made porous with an electrical current then smashed to bits with ultrasound. Additional treatment alters the physical structure of the flakes to make them glow red when illuminated with ultraviolet light.
Luminescent particles can reveal tumors too tiny to detect by other means or allow a surgeon to be sure all of a cancerous growth has been removed.
These nanoparticles could also help deliver drugs safely, the researchers report. The cancer drug doxorubicin will stick to the pores and slowly escape as the silicon dissolves.
"The goal is to use the nanoparticles to chaperone the drug directly to the tumor, to release it into the tumor rather than other parts of the body," Sailor said.
Targeted delivery would allow doctors to use smaller doses of the drug. At doses high enough to be effective, when delivered to the whole body, doxorubicin often has toxic side effects.
At about 100 nanometers, these particles are bigger than many designed to deliver drugs, which can be just a few nanometers across - a thousand times smaller than the diameter of a human hair.
Their larger size contributes to both their effectiveness and their safety. Large particles can hold more of a drug. Yet they self-destruct, and the remnants can be filtered away by the kidneys.
Close examination of vulnerable organs like liver, spleen and kidney, which help to remove toxins, revealed no lasting changes in mice treated with the new nanoparticles.
University of California - San Diego
Nanoparticles Current Events and Nanoparticles News RSSChemists describe solar energy progress and challenges, including the 'artificial leaf'
Scientists are making progress toward development of an "artificial leaf" that mimics a real leaf's chemical magic with photosynthesis - but instead converts sunlight and water into a liquid fuel such as methanol for cars and trucks.
Magnetic nanoparticles to simultaneously diagnose, monitor and treat
Whether it's magnetic nanoparticles (mNPs) giving an army of 'therapeutically armed' white blood cells direction to invade a deadly tumour's territory, or the use of mNPs to target specific nerve channels and induce nerve-led behaviour (such as the life-dependant thumping of our hearts), mNPs have come a long way in the past decade.
An exquisite container
In campy old movies, Lucretia Borgia swans around emptying powder from her ring into wine glasses carelessly left unattended. The poison ring is usually a confection of gold filigree holding a cabochon or faceted gemstone that can be broken to empty the ring's contents. It is invariably enormous - so large it is rather odd nobody seems to notice it.
Hard Rain: Pitt-led Researchers Create Nano-Particle Coating to Prevent Freezing Rain Buildup on Roads, Power Lines
Preventing the havoc wrought when freezing rain collects on roads, power lines, and aircrafts could be only a few nanometers away.
Knocking nanoparticles off the socks
Scientists in Switzerland are reporting results of one of the first studies on the release of silver nanoparticles from laundering those anti-odor, anti-bacterial socks now on the market.
Magnetic mixing creates quite a stir
Sandia researchers have developed a process that can mix tiny volumes of liquid, even in complicated spaces.
Nanowire biocompatibility in the brain: So far so good
The biological safety of nanotechnology, in other words, how the body reacts to nanoparticles, is a hot topic. Researchers at Lund University in Sweden have managed for the first time to carry out successful experiments involving the injection of so-called 'nanowires.'
Berkeley Researchers Find New Route to Nano Self-Assembly
If the promise of nanotechnology is to be fulfilled, nanoparticles will have to be able to make something of themselves. An important advance towards this goal has been achieved by researchers with the U.S. Department of Energy's Lawrence Berkeley National Laboratory (Berkeley Lab) who have found a simple and yet powerfully robust way to induce nanoparticles to assemble themselves into complex arrays.
Advance in 'nano-agriculture': Tiny stuff has huge effect on plant growth
With potential adverse health and environmental effects often in the news about nanotechnology, scientists in Arkansas are reporting that carbon nanotubes (CNTs) could have beneficial effects in agriculture.
Nanotech protection
Writing in a forthcoming issue of the International Journal of Nanotechnology, Canadian engineers suggest that research is needed into the risks associated with the growing field of nanotechnology manufacture so that appropriate protective equipment can be developed urgently.
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