Microfluidic device for manipulation and lysis of bacterial cells using nanowire array

Abstract

In this master’s thesis, we present a microfluidic device integrated with ZnO nanowire array that aims for rapid detection and analysis of bacterial cells towards widespread use in real fields applications. The proposed detection and analysis of bacterial cells involves three steps: (1) cell manipulation, (2) cell lysis, and (3) detection and analysis of DNA. First, cell manipulation step is performed by hydrodynamic trapping of bacterial cells in the microfluidic device using fishnet-like cage structure array. The fishnet-like cage structures are fabricated by integration of ZnO nanowire array into microslit structures. Since ZnO nanowires synthesized by hydrothermal method are dense and robust enough to endure the moving bacterial cells, they can be trapped at the fishnet-like cages within the microfluidic device without any complicated experimental setup and delicate system control. Second, cell lysis step is conducted by synergic cell wall damage of bacterial cells based on both hydrodynamic (shear-force based) lysis and photocatalytic lysis. For hydrodynamic lysis, moving bacterial cells in the microfluidic device experience collision and friction with ZnO nanowire array. ZnO nanowires are used as the mechanical scratching sources based on their geometry characterized by sharp tips and high aspect ratio. For photocatalytic lysis, bacterial cell wall is disrupted by oxidative damage in the presence of ZnO nanowires and UV light. Through these lysis mechanisms, we can collect DNA for further assay. Lastly, detection and analysis of DNA is achieved by PCR based method which amplifies DNA templates including target sequence after extraction of them from target bacterial cells. It can be demonstrated that the proposed sample preparation strategy can be used for PCR based detection method without serious degradation of DNA templates.