title: Digitally synchronized LCD projector for multi-color fluorescence excitation in parallel capillary electrophoresis detection.
abstract: A simple method is proposed for modulating the excitation light used for multi-color fluorescence detection in a single capillary electrophoresis (CE) channel. In the proposed approach, a low-cost commercial liquid crystal device (LCD) projector with digitally-modulated LCD switches is used to provide the illumination light source and the fluorescence emitted from the CE chip is synchronously detected using an ultraviolet-visible-near infrared (UV-vis-NIR) spectrometer. The modulated light source enables the detection of multiple fluorescence signals within a single CE channel without the need of mechanically switching optical components. In order to enhance the sensing performance of the proposed system, two short-pass filters and one band-pass filter are inserted into the LCD projector to modify the wavelength spectra for fluorescence excitation. With this simple approach, the signal-to-noise (SN) ratio of the fluorescence detection signals is greatly improved by a factor of approximately 22 when detecting Atto647N fluorescent dye. The feasibility of the proposed multi-color CE detection approach is demonstrated by detecting two different samples including a mixed sample comprising FITC, Rhodamine B and Atto647N fluorescent dyes and a bio-sample composed of two ssDNAs labeled with FITC and Cy3, respectively. Results confirm that the digitally-modulated excitation system proposed in this study has significant potential for the parallel analysis of fluorescently-labeled bio-samples using a multi-color detection scheme.
authors.affiliation: Institute of Biomedical Engineering, National Cheng Kung University, Tainan 701, Taiwan.
authors.forename: Shi-Wei
authors.initials: SW
authors.lastname: Lin
authors.forename: Chih-Hang
authors.initials: CH
authors.lastname: Chang
authors.forename: Dai-Yang
authors.initials: DY
authors.lastname: Wu
authors.forename: Che-Hsin
authors.initials: CH
authors.lastname: Lin
mesh_terms: D015374:Biosensing Techniques / Q000295:instrumentation*; D003116:Color; D003124:Colorimetry / Q000295:instrumentation; D003217:Conductometry / Q000295:instrumentation*; D019075:Electrophoresis, Capillary / Q000295:instrumentation*; D004867:Equipment Design; D019544:Equipment Failure Analysis; D008029:Lighting / Q000295:instrumentation*; D050866:Liquid Crystals; D012815:Signal Processing, Computer-Assisted / Q000295:instrumentation*; D013050:Spectrometry, Fluorescence / Q000295:instrumentation*