On-line dynamic detection in the electrophoretic separation by tapered optical fiber interferometer

Abstract

We demonstrate a tapered optical fiber interferometer integrated electrophoretic trace mixture separating and on-line detecting device. In this design, we first introduce tapered optical fiber interferometer into electrophoresis system to dynamically on-line monitor the separation of the proteins. The tapered optical fiber interferometer is embedded into the separating medium of the electrophoresis system. The mixture of the proteins with negative charge driven by electric field in the separation gel can be separated and contact with the embedded fiber taper. When the separated components pass through the taper, the refractive index (RI) of the gel around the taper was dynamically adjusted and the interference spectra will present a reversible shift. To visually display the on-line separation and detection process, two kinds of simple proteins of Bovine serum albumin (BSA) and Chicken egg albumin (CEA) labeled with fluorescence indicator are adopted as the analytes in the device. Results show that a trace amount of the proteins (5μl) can be completely separated in the separation gel. Simultaneously, when each component contacts with the tapered region of the optical fiber, interference spectra immediately presents an obvious change because of the dynamic change of the refractive index of the transparent polymer gel. In addition, the complex fixing and developing steps in traditional electrophoresis analysis can be replaced by on-line detection through interference spectra. Then, simultaneous separating treatment and dynamic detection of the proteins are first realized in this experiment. Significantly, this fiber taper integrated separating and on-line detecting device can find great potentials in various analysis fields involves composite samples such as DNA separation and even the virus and cell research.