Jun 13, 2013 |
Light-carved 'nano-volcanoes' hold promise for drug delivery
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(Nanowerk News) Researchers from North Carolina State University have developed a method for creating "nano-volcanoes" by shining various colors of light through a nanoscale "crystal ball" made of a synthetic polymer. These nano-volcanoes can store precise amounts of other materials and hold promise for new drug-delivery technologies ("Three-Dimensional Nanolithography Using Light Scattering from Colloidal Particles").
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The researchers create the nano-volcanoes by placing spherical, transparent polymer nanoparticles directly onto the flat surface of a thin film. They then shine ultraviolet light through the transparent sphere, which scatters the light and creates a pattern on the thin film. The thin film is made of a photoreactive material that undergoes a chemical change wherever it has been struck by the light. The researchers then submerge the thin film in a liquid solution that washes away the parts of the film that were exposed to light. The material that remains is shaped like a nanoscale volcano.
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Researchers from NC State University are able to carve nanoscale "volcanoes" by scattering light through a polymer "crystal ball" onto a photo-reactive thin film. The structures hold promise for new drug-delivery technologies. (Credit: Chih-Hao Chang, North Carolina State University)
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"We can control the pattern of light by changing the diameter of the nanoparticle spheres, or by changing the wavelength – or color – of the light that we shine through the spheres," says Xu Zhang, a doctoral student in mechanical and aerospace engineering at NC State and lead author of a paper describing the work. "That means we can control the shape and geometry of these structures, such as how big the cavity of the nano-volcano will be."
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The researchers developed a highly accurate computer model that predicts the shape and dimensions of the nano-volcanoes based on the diameter of the nanoscale sphere and the wavelength of light.
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Because these structures have precisely measured hollow cores, and precisely measured openings at the "mouth" of the nano-volcanoes, they are good candidates for drug-delivery mechanisms. The size of the core would allow users to control the amount of the drug a nano-volcano would store, while the size of the opening at the top of the nano-volcano could be used to regulate the drug's release.
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"The materials used in this process are relatively inexpensive, and the process can be easily scaled up," says Dr. Chih-Hao Chang, an assistant professor of mechanical and aerospace engineering at NC State and co-author of the paper. "In addition, we can produce the nano-volcanoes in a uniformly patterned array, which may also be useful for controlling drug delivery."
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Chang's team is now working to improve its understanding of the release rate from the nano-volcanoes, such as how quickly nanoparticles of different sizes will "escape" from nano-volcanoes with different-sized mouths. "That's essential information for drug-delivery applications," Chang says.
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"It's exciting to take our understanding of how light scatters by particles and apply it to nanolithography in order to come up with something that could actually help people."
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