Dittonamed's List: Nanoshells

• Once they're in place, infrared light is shined through the skin and down into the tumor site. It's a very simple handheld laser, and it's only for three minutes. Nanoshells absorb light and convert it to heat extremely efficiently, and three minutes is sufficient to kill the cells in the tumor. 

    

   In mouse studies, we were able to observe complete remission of all tumors within 10 days. There were two control groups of mice, and their tumors all continued to grow very drastically until their end. But the mice that were treated with nanoshells, they survived the study. The study was actually a 60-day survivability test. That's considered long-term survivability. Well, at the end of that study, there was 100 percent survivability, and the survivability persisted. That test was done in 2003. It's almost two years later. So it looks like most of those mice will be dying of old age.
• Halas: Nanoshells are injected into the bloodstream, and as they circulate through the blood, they can uptake naturally at a tumor site. That occurs because tumors create many, many blood vessels very rapidly to feed their growth. Those blood vessels have lots of defects, and particles as small as nanoshells can slip through the defects in the blood vessels and take up naturally in the tumor. So over the course of several hours, the nanoshells will gradually accumulate at the tumor site from the bloodstream.

• Because the blood vessels inside tumors develop poorly, small particles such as nanoshells can leak out and accumulate inside tumors. In the test, researchers injected nanoshells intravenously into the mice, waited six hours to give the nanoshells time to accumulate in the tumors, then applied a 5-millimeter-wide laser beam on the skin above each tumor.
• Invented at Rice in the 1990s by Naomi Halas, gold nanoshells are 1/20th the size of red blood cells. They consist of a silica core covered by a thin layer of gold. The size, shape, and composition of the nanoshells give them unique optical properties. By varying the size of the core and the thickness of the gold, researchers can tailor a nanoshell to respond to specific wavelengths of light.
   
    The photothermal cancer treatment uses nanoshells that are tuned to respond to near-infrared light, which passes harmlessly through soft tissue. The nanoshells convert this light into heat that destroys nearby tumor cells. The heating is very localized and does not affect healthy tissue adjacent to the tumor.

• Nanoshells are essentially nanolenses. They capture and focus light around themselves. By controlling the inner and outer thickness of this metallic shell we can control the wavelength of light that this nanoparticle will absorb. They can be effectively delivered to a specific organ or tumor through the bloodstream.

  Once in place, infrared light is shone through the skin and to the tumor. The nanoshells have dramatic heating properties. They absorb the light and convert light to heat with incredible efficiency. This raises the temperature of their local environment by ten to twenty degrees. It turns out, of course, that we are very temperature-stable organisms, so if you raise the temperature of our cells by twenty degrees our cells will die. So this is a way of very gently and very non-invasively inducing cell death. If I take a nanoshell and I attach it or place it directly next to a cell that I want to destroy and shine light on it then it will convert the light to heat and it will very gently destroy the cell.
• NH: What's interesting about this approach is that it combines diagnostics and therapeutics. The particles can mark where the tumor is and then, once they are in place, you can illuminate the tumor and those same particles will do their task and heat the local environment and destroy the cells, destroying the tumor.
• We invented a particle that we called nanoshells. The structure is basically a coated sphere. The inner core of this particle is made out of glass and the outer shell is made out of gold.

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• Nanospectra Biosciences, Inc. is commercializing a particle-based therapy for the selective and precise thermal destruction of solid tumors while minimizing damage to healthy adjacent tissue and preserving critical structures.  This medical device, AuroLase™ Therapy, is broadly applicable to most solid tumors, and we have an open Investigation Device Exemption (IDE) to conduct the first clinical trial in patients with head and neck cancer.  This trial is expected to commence in early 2008. 
   
    AuroLase Therapy utilizes the unique “optical tunability” of a new class of materials developed at Rice University.  These AuroShell™ particles (also known as nanoshells) can be designed to absorb different wavelengths of light, including the near-infrared wavelengths that can penetrate human tissue.  The particles are delivered intravenously to the tumor and then the area is illuminated with a near-infrared laser.  The particles will selectively absorb this near-infrared energy, converting the light into heat to thermally destroy the tumor and the blood vessels supplying it without significant damage to healthy tissue.