Development of a microfluidic device for DNA diagnostics

New DNA analytical methods are needed to meet the goals set by the completion of the human genome for DNA diagnostics and gene expression. A current trend has been the integration of multiple analytical processes in a credit card sized device, which is capable of high throughput analysis, automation, and is cost effective. With the continuing development of these micro-Total Analysis Systems (μTAS) and sensitive DNA recognition technologies, it is often desirable to immobilize biomolecules within microfluidic channels in small well defined areas. New methods were developed to allow spatially-directed attachment of biomolecules to micron-sized regions within the microfluidic channel using photochemical and electrochemical oxidation of biotin/avidin.; The focus of this work is the development of a microfluidic chip, which allows for the direct detection of several distinct DNA targets. The first goal of this research was to create micrometer-sized domains on polymer surfaces that were chemically modified in order to immobilize biosensing elements using biotin/avidin chemistry. A carbene-generating photobiotin was used with a modified protocol in order to improve the homogeneity of the surface derivatization reaction. A prototype microfluidic sensor was then developed to detect fluorescently labeled DNA targets within PDMS microfluidic channels. A new method was developed to allow spatially-directed attachment of DNA probes to micron-sized regions on a gold surface using electro-oxidation of biotin/avidin hydrazide. Electrodeposition of biotin/avidin hydrazide allows a fast one-step procedure that completely covers the gold surface.; Applications of this research were a flow encoded microfluidic device for detecting multiple DNA targets within a single microchannel. The target DNA is identified based on its elution time. Multiple genetic sequences were detected by using a single microfluidic device with this method. The other application was a DNA sensing microfluidic device that hybridizes different polymerase chain reaction (PCR) fragments from an offline PCR mixture and separates them based on fragment size. In conclusion, the goal of my research has been to implement DNA biosensing regions within a microfluidic device, and to further the development of applications for micro total analysis systems.