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Study Of Monolithic Pouring Derivative PDMS Chip-based Electrophoresis Microsystem And Its Application

Posted on:2006-08-26Degree:MasterType:Thesis
Country:ChinaCandidate:R ChenFull Text:PDF
GTID:2121360155972716Subject:Medicinal chemistry
Abstract/Summary:PDF Full Text Request
Miniaturized total analysis system( μTAS) is based on micro-electronic machine-system (MEMS) fabrication technology, which coupled with analytical chemistry and biochemistry, and integrated analytical process on microchip to make the whole analytical system miniaturized,integrated and portable from sample preparation to detection. Chip-based electrophoresis is termed as the miniaturized analysis technique that performing electrophoresis and detection in micro channels etched on chips. It not only inherits the characteristic of minimum sample volume (nL) in capillary electrophoresis, but also takes other advantages of miniaturized device, high sensitivity, rapid analysis, durability and complicated integration. However, as a new technique, it still needs to be developed due to the current costly complicated chip fabrication procedures, requirement of quite sensitive detectors and insufficient separation performance. This paper focuses on constructing a CE-chip platform on which sample preparation, electrophoresis separation, and post-column derivatization for chemiluminescence (CL) detection were integrated together on a chip. The biology and drug sample systems attracting attentions of analysis researchers were taken to validate the performance of the device. Furthermore, the effects of operation parameters were investigated so as to carry out separation with high performance and sensitivity. The work was due to the following three quarters: Firstly, simple cross CE-chip was fabricated applying PDMS monolithic pouring method, of which the electrical characteristics concerning electroosmosis and its stability and as well the linear range of voltage-current curve were discussed. The operation and detection parameters were optimized according to the electrical characteristics of micro channel and properties of amino acids sample system, so as to validate the possibility of applying these chips to perform effective analysis. With the optimized operation parameters of amino acids, sodium borate running buffer was prepared to 5mmol·L-1,pH=9.24, injection voltage was set to 500 for 5s loading, separation and derivative voltages were 1440V and 400V respectively, which resulted in a resolution 2.29 of two amino acids. Taking account for the base line rise induced by the CL detection in the end reservoir of separation channel, post-column "Y"shaped CL derivative reaction channels were designed to eliminate this phenomena. The channel networks were modeled to be DC resistance circuit in order to obtain optimum operation voltages. With this design-improved chip, the resolution of amino acids was increased to 2.29 from 1.37 in the simple cross CE-chip, the detection limit was lowered to 2.5fmol from 4.5fmol. Evidently, this chip design can quite avoid base line rise, improve the resolution and sensitivity. In this paper, the fabricated PDMS chip was integrated with the high sensitive CL detection system to form a miniaturized electrophoresis on chip system (MCE). The constructed CE-chip system was applied to microanalysis of phenothiazines drugs in human spit that was of importance in clinic analysis. As for promazine hydrochloride and chlorpromazine, phosphate running buffer was prepared to 10 mmol·L-1, pH=3.5, injection voltage was set to 500 for 5s loading, separation and derivative voltages were 2600V and 500V respectively, which yielded a resolution 1.51 of these two drugs. The detection limits are 2.51×10-8 g·mL-1and 5.00×10-8 g·mL-1, respectively. The pre-column membrane was integrated in the sample reservoir to eliminate the interference of proteins in spit. Applying optimized operation parameters, injection voltage 700V for 8s, filter equilibrium interval 60s, the detection limits of promazine hydrochloride and chlorpromazine were 4.5×10-8 g·mL-1 and 6.5×10-8 g·mL-1, respectively. Both samples could be detected in wide linear range and low detection limit. Compared the two modes with and without membrane, the former showed short elution time, high peak value and low RSD value relatively, which demonstrated the contributions of filter membrane. The assembled μTAS system demonstrated its potential applications in analysis complicated samples, especially for biopharmaceutical analysis, clinical diagnose and interactions investigation of drugs.
Keywords/Search Tags:monolithic pouring PDMS chip, post-column derivative channel, fluidic controlling in micro channels, pre-column membrane separation
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