Balaji Sitharaman wins Texas Nanotech Award  
by: Francis C. Assisi

22 January 2005 -- Two people of Indian origin - Balaji Sitharaman and Bharat Bhushan -- made news in science and technology last week.

The Nanotechnology Foundation of Texas (NFT) announced that it has selected Rice University doctoral student Balaji Sitharaman as one of two winners of the 2004 George Kozmetsky Award for Outstanding Graduate Research in Nanotechnology. The award is for Sitharaman´s efforts to create a revolutionary new class of contrast agents that could, for the first time, allow magnetic resonance imaging of individual cells.

Sitharaman’s work has primarily involved creating derivatized nanotubes that can dramatically improve magnetic resonance imaging contrast in the detection of cancer cells. His research also impacts practical medical applications where nanotubes can be used to deliver therapeutic agents, such as radioactive isotopes, to specific tumors.

Chairman of Rice’s Chemistry Department, Denton H. Whitmire, said this about Sitharaman’s work: “These projects have a high probability of leading to real-life applications of nanotechnology in the near future.”

"Balu is one of the best graduate students I have worked with in my 30 years at Rice," said Lon Wilson, professor of chemistry and Sitharaman´s Ph.D. advisor. "He´s already produced six peer-reviewed manuscripts that have been published or accepted by first-rank journals, and it´s likely that he´ll double that by the time he graduates."

More than 25 million patients in the U.S. undergo MRIs annually, and doctors use contrast agents in almost of quarter of those procedures. Contrast agents increase the sensitivity of the scans, making it easier for doctors to deliver a diagnosis. The most effective and commonly used contrast agent is the toxic metal gadolinium.

Sitharaman has created new forms of contrast agents by encasing gadolinium inside fullerenes. Fullerenes are single molecules of carbon atoms arranged in spherical or tube-shaped structures. By enclosing the gadolinium inside the carbon molecules, Sitharaman has simultaneously reduced the toxicity of the metal to near zero while boosting its effectiveness as a contrast agent.

One of Sitharaman´s creations is a buckyball encasing a single atom of gadolinium. More recently, he has discovered a method of encasing as many as 100 atoms of the metal inside a short length of carbon nanotube. The resulting "gadonanotubes" are 100 times more effective as contrast agents than the best forms in clinical use.

In future work, Sitharaman plans to use existing methods of attaching antibodies and peptides to fullerenes to try to create a contrast agent that will bind only with diseased cells such as cancer cells. He is hopeful that these tissue-specific imaging agents might allow for the first intracellular, individual cell MRIs.

"I m grateful and honored by this recognition by the Nanotech Foundation of Texas and look forward to the benefit of our research to diagnostic medicine," said Sitharaman. Sitharaman and University of Texas at Austin student Aaron Saunders were named as this year´s Kozmetsky Award recipients on Jan. 12. The prestigious award includes a $5,000 prize.

The awards are the first of their kind offered to U.S. graduate students working on nanotechnology. According to Conrad Masterson, founder and president of NFT, “These awards recognize the great work underway at Texas universities. Our goal is to help attract the brightest young people in the nation to conduct nanotechnology research; make groundbreaking discoveries; and commercialize products that derive from their work in this state."

Competition for the awards is fierce. A scientific review board composed of recognized experts in nanotechnology research used a numerical score to rate each submission. Only 42 out of a possible 400 points separated the four top finalists. The 18 nominees represented diverse fields, including medicine, engineering and natural science. The finalists represented four different universities, including Rice University, The University of Texas at Austin, Texas A&M University and The University of Texas at Dallas.

The NFT established the George Kozmetsky Award for Outstanding Graduate Research in Nanotechnology as a result of generous donations from the public. The winners will also have an opportunity to address the 2005 Nano Summit that takes place on July 28, 2005.

BHARAT BHUSHAN FINDS SOLUTION FROM LOTUS LEAF

Ohio State University engineers are designing super-slick, water-repellent surfaces that mimic the texture of lotus leaves. The patent-pending technology could lead to self-cleaning glass, and could also reduce friction between the tiny moving parts inside microdevices.

Scientists have long known that the lotus, or water lily, makes a good model for a water-repellent surface, explained Bharat Bhushan, Ohio Eminent Scholar and the Howard D. Winbigler Professor of mechanical engineering at Ohio State. The leaf is waxy and covered with tiny bumps, so water rolls off.

In studying the lotus leaf, Bhushan realised that the same texture could be exploited to reduce friction between moving parts on machines. Small machines, such as those under development in the fields of micro and nanotechnology, cannot be lubricated by normal means, and would especially benefit from the technology.

´In general, what´s good for water-repellency is good for fighting friction,´ Bhushan said. But when it comes to designing high-tech surfaces, for instance, a water-repellent car windshield or a low-friction joint on a micromachine, just copying a lotus leaf isn´t enough. Bumpy, waxy surfaces can actually become sticky under some circumstances. ´What people don´t know is what kind of surface is optimal,´ he said.

So he and his colleagues have built the first computer model that calculates the best bumpy surface for different materials and applications. With the right kind of texture, manufacturers could make self-cleaning windows. Because the bumps would measure only a few nanometres high, and would be made of a transparent material, the window would look like any other but still repel water and dirt.

So far, Bhushan´s team has focused on modelling bumps of different sizes and shapes. All the bumps included in the model aid water repellency by keeping water droplets from directly touching the surface.

Because the bumps are so much smaller than a droplet and so close together, they cannot puncture the droplet. Bhushan´s model calculates how and where to place the bumps so that the droplet will contact the surface in just the right way to roll off. In cars, water-repellent glass would improve safety by helping drivers see better, especially during inclement weather. Right now, drivers can spray coatings on car windows to accomplish much the same thing, but those coatings wear off. Because the new technology builds water-repellency into the surface of the window, it would continue to work for the lifetime of the window.

Though drivers may rejoice at the idea of less window cleaning, Bhushan is most excited about what his technology could do for microelectronics. In 2001, his team developed the first direct method for measuring the friction between moving parts inside micromachines, and he has since been working on methods to reduce that friction.

Some of Bhushan´s industrial partners are building light-based electronics in which tiny mirrors move to reflect light in different directions. Others are working on very small sensors that detect and process chemical samples. Both kinds of devices are too small to use traditional lubricants on the moving parts.

One way to eliminate the need for lubricant is to build slick surfaces onto each individual part. Bhushan suspects his lotus-leaf surfaces might do the job. Manufacturers would just have to use his model to figure out what size and shape bumps are best for their application.

francisassisi@hotmail.com


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