Cell-based Microfluidic Disease Diagnosis And High Throughput Drug Screening Systems

In recent years, with the rapid development of technologies for fluid handling and cell culture in microfluidic systems, microfluidic systems have become important platforms for disease diagnosis and treatment. Cell mechanics can be regarded as a biomarker for early diagnosis of diseases. However, current microfluidic devices for analyzing cell mechanics usually have complicated structure. Cell based high throughput screening is the primary way for drug discovery. However, it is difficult for most of the current cell-based microfluidic high-throughput screening in systems to achieve long time cell culture, and flexible liquid handling with low drug consumption.In this thesis, two works are introduced including a microfluidic system for distinguish cell mechanics by analyzing cell recovery curve after cell deformation, and a droplet-based microfluidic system for high-throughput drug screening.In Chapter1, the current progress of microfluidic systems for analyzing cell mechanics and cell-based high-throughput drug screening is reviewed. Various microfluidic techniques for cell mechanics analysis are introduced including distinguish of cell mechanics and quantitative analysis of single cell mechanics by microfluidic systems. The systems of cell-based microfluidic high-throughput drug screening under continuous flow, droplet and microarray modes are also reviewed.In Chapter2, a simple microfluidic system for cell mechanics analysis is introduced using a poly(dimethylsiloxane)(PDMS) chip with an actuated flexible membrane. To demonstrate the feasibility of the present system,3T3fibroblasts and HL60cells are tested as the model cell samples. The device can be used to distinguish between cells with different mechanical structure in a quantitative way, and makes it possible to study changes in the mechanical response with low cell consumption.In Chapter3, we present an integrated microfluidic system for cell-based drug combination screening based on the sequential operation droplet array (SODA) technique, with drug consumption of5μg for each drug screening experiment. Various droplet manipulations including liquid metering, depositing, mixing, transferring, and removing were flexibly realized on demand in the system, to achieve complex multi-step operations for drug combination screening involving cell culture, medium changing, schedule-dependent drug dosage and stimulation, and cell viability testing. Parallel screening with342addressable and different drug combination conditions could be achieved on a single PDMS chip with a size of6cm×6cm. This system was applied in schedule-dependent drug screening for A549non-small lung cancer cells with combinations of cyclin-dependent kinases inhibitor flavopiridol and two widely applied anti-cancer chemotherapy drugs, namely paclitaxel and5-fluorouracil. The highest inhibition efficiency was determined with this system.