Research On Microfluidic Chip-based DNA Biosensor

In this thesis, we design a series of novel DNA biosensors, which based on microfluidic chip, in hope of providing a rapid, selective and sensitive method for the clinical diagnoses of DNA. The main contents of the thesis including:(1),the development of a novel micro-fluidic chip-based label-free DNA biosensor, which utilized the electrophoretic driving mode and magnetic beads (MBs)-based "sandwich" hybridization strategy. The proposed DNA biosensor has much more robust resistibility to the complex matrix of real saliva and serum samples, shorter analysis time and much higher discrimination ability for the detection of single-base mismatch, and can be used for the sensitive and ultra-speciafic detection of label-free DNA. By using the biosensor, we have successfully determined oral cancer-related DNA in saliva and serum samples without sample-labeling and any pre-separation or dilution with a detection limit of 5.6×10-11 M, a RSD (n=6)<5% and a discrimination factor of 3.58-4.54 for one-base mismatch.(2), The developed of a micro-fluidic chip-based DNA biosensor for the simultaneous detection of two different kinds of DNA sequences by using on-line field amplified sample injection (FASI) mode. The proposed DNA biosensor is simple, low-cost, selective and sensitive, it can be used for the simultaneous detection of two different DNA sequences with a higher sensitivity due to the utilization of on-line field amplified sample injection (FASI) mode. By using the proposed biosensor, we have successfully determined two DNA sequences, which related to oral cancer and human immunodeficiency virus, in the saliva san serum sample with a detection limit of 2.2×10-12 M and 1.8×10-12M respectively, a RSD (n=5)<7% and a recovery of 90-108%.