Chip takes over lab routine
Stamp-sized device could assess workings of single cell.
By shrinking laboratory machines to minute proportions, California scientists have built a postage stamp-sized chip that drags DNA from cells. The device might one day shoulder some of scientists' routine tasks.
Next-generation versions of the chip could process hundreds or thousands of samples and might supplant expensive lab robots. "We want to get these tools into the hands of the masses," says Steven Quake of the California Institute of Technology, Pasadena.
Many researchers are developing ways to miniaturise individual laboratory tasks such as splitting apart cells. But Quake's team are the first to link them up, and carry out the procedure on multiple samples at the same time. "Nobody put them together like this before," says bioengineer Luke Lee of the University of Berkeley, California.
A series of tiny O-shaped channels, each of which serves as a mixing vessel, is carved in a rubber chip, the team report in Nature Biotechnology1. A network of inlet canals and valves feeds each O-channel with a mixture of cells and the chemical solutions that dilute and burst them.
Tiny moving plugs in each O-channel swirl the contents like a cement mixer, so that the cells pop and release their DNA, which is sucked out the other side. The intricate connections resemble the complex circuit board of a computer chip. "It is a fascinating and fantastic job," says Lee.
On a second prototype chip, Quake's team went on to show how they could extract and analyse DNA from a single cell, rather than a group of them. Ultimately, they want to add tools that can analyse the cell's DNA and read out which genes are active.
Biologists would use such tools to probe the workings of single cells. They might, for example, use it to identify a rare cancerous blood cell that is about to trigger a leukaemia relapse but is swimming among healthy neighbours.
Most techniques today tend to analyse groups of cells, which can mask a single cell's erratic behaviour. "If there are 10,000 cells and one is the cell you want, you will not see [its effect]," explains geneticist French Anderson of the University of Southern California, who collaborated with Quake.
Some researchers have started analysing single cells with conventional laboratory techniques. But shrinking the size of each chemical reaction cuts the cost of reagents and slashes the time taken for each step, explains Anderson. "You can ask biological questions that you simply cannot ask with larger systems," he says.
- Hong, J. W., Studer, V., Hang, G., Anderson, W. F. & Quake, S. R.. Nature Biotechnol, doi:10.1038/nbt951, (2004).