Lab-on-a-chip nanoscale array monitors cellular processes

Researchers at Tel-Aviv University in Israel have developed a lab-on-a-chip device that can incorporate enzymes and even living cells in a nanoscale array capable of monitoring electrochemical reactions. This device could prove invaluable in drug discovery and metabolism studies and as a diagnostic device for use at a patient's bedside or in a doctor's office.

Writing in the journal Sensors and Actuators B: Chemical, a research team headed by Yosi Shacham-Diamand, Ph.D., describes its efforts to merge the biochemical sensitivity of living cells with the monitoring ability of silicon-based microelectronics. The end-product of this research is a portable device consisting of two components: a disposable chip and a reader. The disposable silicon chip, constructed using standard microelectronic fabrication methods, contains an array of eight 100-nanoliter wells, each with three embedded electrodes independently wired to perform a wide variety of electrochemical measures. The reader is comprised of a multiplexed electrical monitor connected to a pocket-sized personal computer. The entire device weighs about two pounds, though the investigators note that it should be possible to further shrink the size and weight of the apparatus.

In one demonstration of the device's utility, the investigators quantified levels of the enzyme alkaline phosphatase in nanoliter volume samples; evidence suggests that levels of this enzyme may be diagnostic for metastasis in breast and colon cancer patients. The researchers also showed that the device can be used to monitor circulating drug levels in real time, which could prove useful for determining whether patients are receiving optimal levels of anticancer agents.

In additional studies, the investigators showed that their device can monitor biochemical changes in cells grown in the nanoliter wells. Using bacteria, the researchers measured metabolic changes in response to chemical added to the bacterial growth medium. The researchers note that this approach should work with mammalian cells. They also suggest that it should be possible to develop an implantable version of this device that would be able to monitor cell responses to drug therapy, for example.

This work is detailed in a paper titled, "Electrochemical detection of biological reactions using a novel nano-bio-chip array." An abstract of this paper is available at the journal's website. View abstract.