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12-03 :: March/April 2012
nanotimes News in Brief
39
Stephan Link, an assistant professor of chemistry and chemical and biomolecular engineering, will help characterize the starfruit nanowires’ ability to transmit a plasmonic signal. That could be useful for waveguides and other optoelectronic devices.
Nanostarfruits begin as gold nanowires with pentagonal cross-sections. Rice chemist Eugene Zubarev believes silver ions and bromide combine to form an insoluble salt that retards particle growth along the pentagons’ flat surfaces. © Zubarev Lab/Rice University
But the primary area of interest in Zubarev’s lab is biological. “If we can modify the surface roughness such that biological molecules of interest will adsorb selectively on the surface of our rugged nanorods, then we can start looking at very low concentra- tions of DNA or cancer biomarkers. There are many cancers where the diagnostics depend on the lowest concentration of the biomarker that can be de- tected.”
Leonid Vigderman and Eugene R. Zubarev: Starfruit- Shaped Gold Nanorods and Nanowires: Synthesis and SERS Characterization, In: Langmuir ASAP, March 09, 2012, DOI:10.1021/la300218z: http://dx.doi.org/10.1021/la300218z
grew into the ridges that gave the rods their star-like cross-section. “Silver bromide is likely to block flat surfaces more efficiently than sharp edges between them,” he said.
The researchers tried replacing silver with other me- tal ions such as copper, mercury, iron and nickel. All produced relatively smooth nanorods. “Unlike silver, none of these four metals form insoluble bromides, and that may explain why the amplification is highly uniform and leads to particles with smooth surfaces,” he said.
The researchers also grew longer nanowires that, along with their optical advantages, may have unique electronic properties. Ongoing experiments with
Cover: Gold nanoparticles created by the Rice University lab of Eugene Zubarev take on the shape of starfruit in a chemical bath with silver nitrate, ascorbic acid and gold chloride. © Zubarev Lab/Rice University
Seen from the side, the nanostarfruit produced at Rice University take on the appearance of carambola, or star- fruit. The particles are about 55 nanometers wide and 550 nanometers long. © Zubarev Lab/Rice University