Gene Detection in a Single Cell

Most people and obviously, every scientist is aware that a cell is the structural and functional unit of every known living organisms. But now we have the results published in the journal Science, issued on January 11, 2008 by Scientists at Arizona State Universityís Biodesign Institute whom have developed the first platform in the world capable of detecting genes.

This platform was completely made up from self-assembled DNA nanostructures. The scientists of the Biodesign Institute at Arizona State University said this could have broad implications for gene chip technology, and may also revolutionize the way in which gene expression is analyzed in a simple and single cell.

Hao Yan, a member of the Instituteís Center for Single Molecule Biophysics said that they are beginning with the most well-known structure in biology, DNA, and applying it as a nano-scale building material. Hao Yan, the leader of this important project is also an assistant professor of chemistry and biochemistry in the College of Liberal and Sciences.

Furthermore she is moving very quickly in the field of DNA Nanotechnology that assembles the molecule of life into a variety of nanostructures with a broad range o applications ranging from human health to nonelectric. As well as all of this, Yan is doing important researches on this field, along with a multidisciplinary team to develop a way to use DNA nanotechnology to target the chemical messenger of genes, called RNA.

Another important research they are involved with is the development of a water soluble nanoarray that can take advantage of the DNA self-assembling process and also have all the benefits that the macroscopic DNA microchip arrays do not have. The advantage is that the arrays themselves are reagents, instead of solid surface chips.

Moreover Yan and her team had designed three different DNA probe tiles capable of detecting three different RNA genes along with a bar code index to tell the tiles apart from each other. Each can be detected by a bar code and were mixed in one solution to be used in a multiplex detection. Also the group uses an atomic force microscopy which is a powerful instrument that allows the researchers to see the tiles at a single molecule level.

Other probes on the surface of each DNA demonstrated that the tile is a dangling single stranded piece of DNA that can bind to the RNA target of interest. Yan explained that each probe actually has two half probes, so that when the target RNA comes in, it will hybridize to the half probes and turn the single stranded dangling probes into a stiff structure. Beside of this when it is stiffened, it will be sensed by the atomic force microscope cantilever, and you can see a bright line, which is a height increase.

This project leader (Hao Yan) said 'This is one of the first practical applications of a powerful technology that, till now, has mainly been the subject of research demonstration. Also the field of structural DNA nanotechnology has recently seen much exciting progress from constructing geometrical and topological nanostructures through tile based DNA self-assembly initially demonstrated by Ned Seeman, Erik Winfree and colleagues'.

The Biodesign Institute at Arizona State University is aware of technology and whit it is capable of. They ague that in few seconds it can detect large quantities of RNA. 'Since the DNA-RNA hybridization has such a strong affinity, in principle, a single molecule would be able to the probe tile,' said Yan.

However Yan argues that the amazing potential of structural DNA nanotechnology in biological applications is not receiving the real value it has. She also said that if we look at the process of DNA self-assembly, we'll notice how trillions of DNA nanostructures can from simultaneously in a solution of few micro-liters, and very importantly, they are biocompatible and water soluble. Although there are still many important goals to overcome and the team is very excited and motivated to achieve the objective.

The economical factor is obviously tied to all of the scientific process, that's why DNA chip and microarray technology have become a multi-billion dollar industry. Yan has been setting a clear objective; she said that the ultimate goal is detect RNA gene expression at the single cell level.

By: Hector Nicolas Suero

NanoVip - Staff Writer