Chemistry

From Soup to Nuts

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Science  19 Jan 2007:
Vol. 315, Issue 5810, pp. 302
DOI: 10.1126/science.315.5810.302c

The promise of microfluidic systems, in which very small volumes of liquids are manipulated, processed, and interrogated, is that it may be possible to develop low-cost diagnostic systems, particularly for use under challenging field conditions. Although there has been tremendous progress in developing microfluidic components, creating an integrated system that can analyze an unpurified sample has remained a goal.

Easley et al. describe a microfluidic system with three distinct functional domains. The first two are for sample preparation, consisting of solid-phase extraction (SPE) to pull out sample DNA from a crude specimen and for subsequent PCR amplification. After this, the amplified products are then injected along with a DNA standard into an electrophoretic detection domain. One key aspect of the device (3 × 6 cm) is a series of valves that are used to isolate each unit, thus keeping SPE reagents from reaching the PCR domain; these valves are also used in a diaphragm-like fashion to pump the amplified DNA into the analytical chamber. The authors demonstrate the detection of Bacillus anthracis in 750 nl of whole blood taken from infected but asymptomatic mice, and they also are able to measure Bordetella pertussis in 1 μl of nasal aspirate taken from a patient suspected of having whooping cough. — MSL

Proc. Natl. Acad. Sci. U.S.A. 103, 19272 (2006).

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