Array Speeds Protein, DNA Analysis

Michael D. Wheeler

Researchers at the University of Alberta have developed a capillary electrophoresis system that can significantly speed protein analysis and DNA sequencing.

Most commercial capillary electrophoresis systems have one capillary. After exposure to an electric field, the analyte separates and migrates through the capillary. During this migration, an argon-ion laser excites fluorescence. As each of the components is driven into discrete bands, the system detects and quantifies the analyte.

The drawback is that a single capillary limits evaluation to one sample at a time, making tasks such as DNA sequencing very time-consuming. This shortcoming led professor Norman Dovichi to develop a multicapillary instrument. The device features a two-dimensional array with 96 wells in a rectangular piece of optical quartz called a sheath flow cuvette, which serves as a chamber for postcolumn detection.

Laser-induced fluorescence occurs after the analyte passes through the capillary. A camera lens detects and collimates the fluorescence, which is dispersed spectrally with a large prism. It is reimaged on a high-efficiency camera, permitting the measurement of spectral dispersion of fluorescence. This eliminates the need for a filter wheel to distinguish among fluorescently labeled primers.

The next step may be finding ways to pack even more capillaries into an array.

The instrument has been used on DNA sequencing plates and dye-labeled protein samples.