Nanowire-integrated microfluidic device and its application to breast cancer cell analysis

Abstract

In this dissertation, we proposed nanostructure integrated microfluidic device for the analysis of breast cancer cells and nanowire utilized detection device. The microfluidic device could efficiently and economically complete the experiments performed in the laboratory using a small sample amount in the microfluidic channel. Nanostructures have been actively studied in the field of bioanalysis due to their various electrical, mechanical, and chemical characteristics. In this study, we developed an efficient microfluidic device using advantages of microfluidic system and nanostructure. This study introduced two types of biological analysis devices. The first device is a microfluidic device for sample preparation, especially for cell lysis. We first analyzed the cell lysis probability by analyzing the flow shape and shear rate in the channel through the numerical analysis method. For device fabrication, zinc oxide nanowires were integrated into microfluidic channels and the cells were lysed mechanically. At this time, the zinc oxide nanowire was synthesized on the substrate or integrated on the surface of a microstructure prefabricated in microchannel. When cells introduced into the microfluidic channel, the cell membrane was caught on the surface of the nanowire, and stretched by the flow. Cells that have stretched longer than a certain length would burst, and intracellular materials such as proteins were extracted. In this study, cell lysis was performed using MCF 7 cells, and the obtained samples were analyzed for estrogen receptor alpha (ER-alpha) using an enzyme-linked immunosorbent assay (ELISA). We confirmed the effect on the cell lysis efficiency by controlling the velocity in the microfluidic device. Although the efficiency of cell lysis was improved up to Re = 9, due to the deformation effect of the PDMS channel, the efficiency of collision with the nanowire or microstructure decreased under the abnormal condition, thereby reducing the dissolution efficiency. Based on the size of the cells, the arrangement of microstructures, the speed of the fluid can be adjusted to effectively lysis of the cells. The second device was a device for immunoassay using nanowires. We have proposed a platform for the detection of carcinoembryonic antigen (CEA) using the large reaction surface area of nanowires and the excellent fluorescence signals of quantum dots. CEA was detected by sandwich immunoassay on the nanowire, and the fluorescence signal from the tagged quantum dots was analyzed for CEA concentration. The fluorescence resonance energy transfer (FRET) phenomenon occurred in which the energy of the quantum dots was transferred to the zinc oxide nanowire, and the signal of the quantum dots was reduced. In order to suppress this phenomenon, biotin-streptavidin linker was used to reduce the distance between two nanomaterials, and analysis using ZnO nanowire and quantum became possible. The proposed immunoassay method has excellent selectivity and wide dynamic range. It also showed the possibility of multiple detection by showing the possibility of labeling using several kinds of quantum dots. In the real breast cancer diagnosis, from the biopsy to diagnosis takes 4 ~ 7 days due to the complicate or time-consuming process such as paraffin embedding. However, if we successfully connect these devices, it will take less than one day until diagnosis which means it shorten the days with anxiety to the patients and time to decide in-depth or other examination for diagnosis to doctors.