Studies On A Microfluidic High-throughput Concentration Gradient Droplet Generator And Its Application For Crystallization Of Protein

Droplet-based microfluidics is a technology for manipulating liquid in small scale. This technology offers several attractive features:low consumption of samples and reagents, stable condition of reaction, fast mixing, etc. More and more investigators have paid attention to the formation of high-throughput droplet for increasing of analysis throughput. In this work, we designed a novel microfluidic chip for forming concentration gradient droplets using T-junction, which is developed from a microfluidic concentration gradient chip designed by our group. And then, screening of protein crystallization conditions in this microfluidic chip was studied.In chapter1, the development of droplet-based microfluidic systems was reviewed, and the limitations of the systems were discussed. And also their application to protein crystallization was introduced. In the end, the aim and the consideration of the present work were given.In chapter2, a novel, high-throughput microfluidic concentration gradient droplet generator was designed based T-junctions. The channel network of the concentration gradient generator was used as aqueous phase channels, and oil phase channels were arranged at the outside of the network. The droplets with different contents were formed only depending on the channel structures requiring no peripheral equipment. The concentration gradient droplets were demonstrated using a dye solution and paraffin liquid. The concentration gradient of the droplets was in agreement with theoretical value. The influence of surfactant on the droplet formation was studied. When the concentration of surfactant was greater than its critical micelle concentration, the size of droplets remained about unchanged. Then, the effects of flow rate on the droplet size and droplet generation were investigated, and the RSD of fifteen droplets size in the same channel was1%-3%, while in sixty-four different channels was6%-13%.In chapter3, screening lysozyme crystallization conditions in the high-throughput concentration gradient droplet generator was carried out. Compared with traditional methods, this system features low consumption of reagents, high-speed of crystallization, screening of various conditions at a single operation.In the last chapter, the microfluidic concentration gradient droplet generation system was summarized.