| Description |
DNA extraction automation is a major concern in molecular diagnostics where processing of numerous and daily samples of blood represent a labor-intensive task and are difficult to automate. With the rapid growth in the area of DNA diagnostics, there is an urgent need for the development of a microsized total analysis system which can perform all three of the primary tasks of nucleic acid-based diagnostics on a single chip: sample preparation, extraction of the DNA, detection and quantification. This thesis work presents design and fabrication of an integrated system that can extract and electrochemically quantify DNA simultaneously from any unknown sample on a single chip. The system is fabricated using aluminum oxide membranes as substrates for the extraction and quantification of DNA, bonded with the PDMS (Polydimethylsiloxane), whose layer provides the microfluidic inlet and outlet. Cost effective fabrication tools, such as Xurography (a knife plotter) and soft lithography, are used to obtain integrated hybrid fluidic and detector prototypes. Characterization of the DNA quantification system is performed based on several important operational parameters such as different concentrations of gDNA (sample), voltage applied to the electrochemical detector, flow rate of the sample and carrier buffer and channel gap size between the detector electrodes. Three experiments with different experimental setup are applied to quantify the binding of DNA with the surface of aluminum oxide membranes. The change in the current through the detector wires is found to be linear with different concentrations of gDNA. Using these experimental data, a calibration curve is obtained through which concentration and mass of gDNA that is extracted from an unknown sample can be determined successfully. This system thus provides us with several advantages, such as simultaneous extraction and quantification of gDNA, low detection limit of DNA (3.3ng/^L), low sample volume (200^L), high sensitivity and selectivity, low cost, small size, easy fabrication, portability, and disposability, when compared to other quantification systems. |
