Microfluidic Chip-based Studies On Genentic Diagnosis And Cell-drug Interaction

This thesis focuses on developing microfluidic chips for biomedical applications on genetic diagnosis and cell-drug interaction. The in-house built microfluidic system was applied in genetic diagnosis.(1) We analyzed SARS coronavirus genome with bioinformatics tools and selected sequence specific region for primer design, and applied microfluidic chip electrophoresis, in combination with reverse transcription-multiplex PCR, in genetic diagnosis of 18 SARS cases; (2) We designed and fabricated a microfluidic chip integrated isotachophoresis preconcentration and sieving electrophoresis separation, which can attain 300 times lower detection limit than that of conventional electrophoresis microchip. The microfluidic chip-based analysis, in combination with subtype sequence specific PCR, was used in genotyping of 200 Hepatitis B virus cases. This method provided genotyping information in reduced PCR amplification time with higher detection rate when compared with conventional methods. The above work showed that microfluidic chip for genetic diagnosis has advantages of high sensitivity, high resolution, fast separation and low consumption. It has the potential to be used in clinical genetic diagnosis.Microfluidic chip was also used in study on cell-drug interaction. We designed and fabricated a microfluidic chip featuring parallel-gradient generating networksfor studying cell-drug interaction. The microfluidic chip contains 5 gradient generators and 30 cell culture chambers where the resulted chemical concentration gradients are delivered to stimulate on-chip cultured cells. This microfluidic chip exploits the advantage of lab-on-a-chip technology by integrating cell seeding, culture, stimulation and staining into a single chip. The microfluidic chip was applied in studying the role of reduced glutathione (GSH) in MCF-7 cells'chemotherapy sensitivity. Suppression of intracellular GSH by treatment with arsenic trioxside has been shown to increase chemotherapy sensitivity; conversely, elevation of GSH production by treatment with N-acetyl cysteine leads to increased drug resistance. The results indicated that high GSH level has negative effect on chemotherapeutic sensitivity, and depletion of cellular GSH may serve as an effective way to improve chemotherapy sensitivity. The microfluidic chip is able to perform multiple chemical stimulating and multiparametric cell analysis with easy operation, thus holds great potential for extrapolation to the high-throughput drug screening.