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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 RSSSweet -- sugared polymer a new weapon against allergies and asthma
Scientists at Johns Hopkins and their colleagues have developed sugar-coated polymer strands that selectively kill off cells involved in triggering aggressive allergy and asthma attacks.
Small nanoparticles bring big improvement to medical imaging
If you're watching the complex processes in a living cell, it is easy to miss something important-especially if you are watching changes that take a long time to unfold and require high-spatial-resolution imaging.
Nanotech in Space: Rensselaer Experiment To Weather the Trials of Orbit
Novel nanomaterials developed at Rensselaer Polytechnic Institute are scheduled to blast off into orbit on November 16 aboard Space Shuttle Atlantis.
Behavior modification could ease concerns about nanoparticles
In an advance that could help ease health and environmental concerns about the emerging nanotechnology industry, scientists are reporting development of technology for changing the behavior of nanoparticles in municipal sewage treatment plants - their main gateway into the environment.
Engineers image nanostructure of a solid acid catalyst and boost its catalytic activity
The catalytic processes that facilitate the production of many chemicals and fuels could become much more environmentally friendly thanks to a breakthrough achieved by researchers from Lehigh and Rice Universities.
Findings show nanomedicine promising for treating spinal cord injuries
Researchers at Purdue University have discovered a new approach for repairing damaged nerve fibers in spinal cord injuries using nano-spheres that could be injected into the blood shortly after an accident.
Chemists 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.
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