Chip tests antibiotics' effectiveness

Researchers at the University at Buffalo have come up with a chip that can rapidly determine whether a person has been exposed to toxins or radiation, or whether ingested medicines are working.

The sensor, which will be more fully described in an article in American Chemical Society journal Analytical Chemistry on Tuesday, essentially tracks what happens to the volume of a cell when exposed to different agents. Within 10 minutes, the chip has been able to track the effect of different antibiotics on E coli cells.

Potentially, the chip could also be used to study the effectiveness of chemotherapy on an individual or detect poisoning before any outward symptoms appear.

Drug designers using the chip could also speed up the testing process because the need to culture bacteria to assess their sensitivity to antibiotics would be eliminated.

Finding better ways to see whether medicines work or poisoning has occurred has long been a subject of medical research. Recent fears about mass biological attacks, however, have prompted the federal government to pour funding into such projects.

Sandia National Laboratories, for instance, has devised what it calls the micro chem lab, a chip that can detect dangerous biological agents in a very small sample of air.

The University of Buffalo system works by measuring the changes in resistance and the output of electrical current in a salt water bath. Salt water conducts electricity. Cells introduced to the solution displace some of the water and reduce the current.

Toxins, however, will cause cells to swell. If a toxic reaction occurs, the swelling cell causes resistance to increase, further reducing the current.

"The new technique is so sensitive, it can detect changes in cell dimensions never seen before in living cells," said Susan Hua, an associate professor of mechanical and aerospace engineering at the university.

While the chip was designed at the University of Buffalo, it was made at Cornell University.