Demonstration of a separations-based fiberoptic sensor for bioanalysis

We present a newly-developed separations-based fiberoptic sensor (SBFOS) fo r biomedical applications. The sensor features a linear 10 cm effective len gth section of capillary coupled with a single optical fiber for laser-indu ced fluorescence (LIF) detection of fluorescently-labeled analytes separate d by capillary electrophoresis (CE). The single optical fiber, arranged per pendicular to and touching the capillary, transmits both laser excitation t o the sensor and analytical signal from the sensor to a PMT-based detection system. The resulting compact, robust design may prove to be an attractive alternative to conventional CE laboratory systems due to the portability a nd potential for automation and multiplexing. The sensor has been evaluated with size selective separations of phi X-174 HaeIII digest DNA samples. Ba seline resolution for fragments differing by 10 base pairs was routinely ob served in separations requiring approximately 10 min. This short analysis t ime, combined with rapid sensor regeneration capability, enabled the tempor al analysis of a digestion of phi X-174 phage DNA by HaeIII restriction enz yme. The use of viscous matrices permits sensor operation in any orientatio n without introducing complications associated with gravity-driven hydrosta tic flow. Relative standard deviations in migration rates of the phi X-174 DNA fragments have generally been less than 5%. Furthermore, efficiencies o f up to 2.5 million plates/m have been observed, giving the compact sensor a separation quality which is competitive with larger conventional CE syste ms. (C) 1999 Elsevier Science B.V. All rights reserved.