| With the increasing concerns on public health and food safety as well as demand of on-site analysis, miniaturized and high sensitive on-site analysis tools have has become one of the most important taskes of analytical chemistry. Micro total analysis system, which has advantages of small reagent and sample consumption, high analysis speed, can be an ideal way for bio-assay and on-site analysis. However, detectors that used for microfluidic analysis are often large in size with high costs. Development of novel highly sensitive detectors that are easy to be miniaturized is one of the important step for on-site analysis with μ-TAS. Laser-induced fluorescence detection (LIF) is widely used for microfluidic analysis, but the traditional laser is expensive, bulky, and is not suitable for on-site use. In order to reduce costs, the light-emitting diodes (LED) have been used as the excitation light sources for fluorescence detection, but the sensitivity of this type detectors are often lower. In this thesis, we first described the attempt of the electrophoretic DNA fragments separation with cyclic olefin copolymer chips. Then an ecnormical LIF detector was designed and assembled with a commercially available cheap violet laser diode as the excitation source, its performance and applications were examined. There are four chapters in this thesis:Chapter Ⅰ, Microfluidics, including the production of chips and and the application of chip electrophoresis has been reviewed. Microfluidic chip electrophoretic separation of DNAs was introduced and the affects of microfluidic devices, type and property of sieving medium as well as common dyes for DNA analysis were summarized. An overview of commonly used detectors of microfluidic analysis was made together with a comparison of different types of detectors. Chapter Ⅱ, With SYBR Green I as an intercalating dye, effect of sieving mediums, such as hydroxypropyl cellulose (HPC), hydroxyethyl cellulose, polyvinyl alcohol, polyethylene pyrrolidone, linear polyacrylamide, on separation of Φx174-Hae III Digest DNA fragment was investigated. It was found that2%HPC gave the best resolution of these DNA fragments in the COC chips. Effect of separation voltage was investigated too, and the results indicated that the best separation was achieved at1.1kV.Chapter Ⅲ, An ecnomical laser-induced fluorescence detector was assembled with a commercially available cheap violet laser diode as excitation source and a photomultiplier tube (PMT) as the photoelectric conversion device which arranged in a confocal optical configuration. Factors including the magnification of objectives, optical filters, current of the laser diode and gain of the PMT, were investigated according to the performance of the detector. Fluorescamine and fluorescein isothiocyanate derivatized amino acids, rhodamine dyes and fluorescein were used to evaluate the sensitivity of the detector. The limit of detection (LOD) of0.02nmol L-was aceived for fluorescamine derivatived leucine. LODs for rhodamine B and fluorescein was9.5and1.0nmol L-1. Compared with other fluorescence detectors that with cheap exciation sources, this detector maintained the advantage of low cost, while the sensitivity is much higher and it could also be used for abroad range of dyes for fluorescent labeling.Chapter Ⅳ, the detector described in the previous chapter was used in the seperation and detection of the fluorescamine derivatives of amino acids, alfalfa seed leaching solution, fluoroquinolones, sulfonated naphthols and CdTe quantum dots. The conditions of amino acids were optimized. The results confirmed the competence of the proposed detector for these different analytes. |
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