Wrapped up in nanotubes

Aranya Goswami, 21, is an undergraduate student at the Indian Institute of Technology. This summer he is visiting the lab of Professor Ardemis Boghossian at EPFL, developing highly precise biosensors based on carbon nanotubes.

Carbon nanotubes are cylindrical tubes of carbon atoms with extraordinary properties across the range: their mechanical, electrical, thermal, optical and chemical abilities pulsate with untapped potential for a multitude of technologies. .

“I’ve always been fascinated by nanotechnology,” says Goswami. “Carbon nanotubes in particular are extremely appealing, given their ‘magical’ properties and that’s why I’ve always wanted to know about them better.”

One of the early problems with carbon nanotubes was that they tend to aggregate and clump together, meaning that they have to be dispersed first in order to be usable. Scientists solved the problem by wrapping polymers around the nanotube.

Goswami is working on a particular type of carbon nanotube referred to as “single-walled”. Because of their ability to fluoresce, these materials are heavily invested in the development of biosensors: devices that use a polymer or biological molecule to detect the presence of chemicals.

When different molecules react with the polymer-wrapped nanotubes, their fluorescence wavelength changes,” says Goswami. “This allows us to predict the particular environment, which is very useful for detecting tumor positions.”

To do all this, Goswami is looking at the behavior of quasiparticles called excitons, which form on the polymer. These are essentially a pair between an electron (a negative charge) and an electron “hole”. Excitons are central in turning carbon nanotubes into biosensors: as they decay they affect the nanotubes’ fluorescence.

“We need to know the mechanism in which the excitons decay in a polymer-wrapped nanotube,” says Goswami. “In other words, we want to find out how fluorescence is affected by the different polymers that we wrap around the nanotube, so that we can design the bio-sensor to fit perfectly into whatever sensing application we want.”

Since very little is known about polymer effects on fluorescence, Goswami looks forward to obtaining some data. “This project seemed exciting from the start, because I think that better sensors will lead to smarter diagnosis and treatment of diseases in the future.” Goswami’s project can provide the basis for building highly efficient and smart biosensors, which will be useful for diagnostics and other applications.

So what’s in the future? Goswami is keen to pursue further studies and focus on the kind of research that will change people’s lives. “My dream is not to earn fame or money but to have fun in my work, to take up challenges on a daily basis, and to get the satisfaction of applying my skills to discover something useful for humanity."