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Honolulu, Hawaii, United States, 2006/11/09 - Researchers at Northwestern University have come up with a relatively easy way to synthesize sub-100 nm nanoparticles that give rise to tunable peaks.
Nanoshells are a novel class of optically tunable nanoparticles that consist of alternating dielectric and metal layers. They have been shown to have tunable absorption frequencies that are dependent on the ratio of their inner and outer radii. Therefore nanoshells can potentially be used as contrast agents for multi-label molecular imaging, provided that the shell thicknesses are tuned to specific ratios. When used as contrast agents, nanoshells of small dimensions offer advantages in terms of delivery to target sites in living tissues, bioconjugation, steric hindrance, and binding kinetics. Besides their improved tissue penetration, smaller nanoshells generate a strong surface plasmon resonance and may exhibit absorption peaks in the visible–near-infrared spectrum. Sub-100 nm nanoshells also provide large surface areas to volume ratios for chemical functionalization that can be used to link multiple diagnostic (e.g. radioisotopic or magnetic) and therapeutic (e.g. anticancer) agents. Researchers at Northwestern University have come up with a relatively easy way to synthesize sub-100 nm nanoparticles that give rise to tunable peaks.
Recent Mie theory simulations suggest that small multi-layer gold nanoshells with diameters of around tens of nanometers can potentially generate a stronger surface plasmon resonance and exhibit ultra-sharp absorption peaks with spectrum widths of the order of 10 nm in the visible–near infrared spectrum, provided that the shells thicknesses are tuned to a certain ratio.
Guillermo A. Ameer, Assistant Professor of Biomedical Engineering at Northwestern University, and his colleagues engineered nanoshells with an overall diameter of around 50 nm consisting of a 20 nm diameter gold nanoparticle core, a tunable dielectric silica middle layer, and an outer gold layer, which is approximately 16 times smaller than previously reported nanoshells.
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