Functionalization And Application Of Microfluidic Chips Of Cyclic Olefin Copolymer

Microfluidics has attracted considerable attention since its establishment in the early 90's last century due to its advantages of miniaturization and integraton. It is a potential technique for rapid analysis of complicated biological samples. However, because of the complexity of fabrication and functionalization and the higher prices of microfluidic chips, their application in routine analysis is limited. The aim of this work was to establish novel low-cost methods for fabrication and functionalization of microfluidic chips for high performance analysis of biological samples. There are three parts in this thesis:1. A high performance chip electrophoresis system was established. Although microfluidic chip based electrophoresis is an important aspect of microfluidics because of its capability of rapid and efficient separation, its overall performance is normally lower than conventional capillary electrophoresis due to the shorter separation channels on the microchips. In this work, cyclic olefin copolymer (COC) micro-chips with long separation channels were made by hot embossing. Through the addition of hydroxypropylcellose into borate buffer,18 aminoacids derivertized with FITC could be separated quickly. The effect of turning radii on the loss of the separation efficiency was investigated. The strategy of arranging long separation channel on a chip in small size was proposed. Equivalent separation capability to the conventional capillary electrophoresis was attained with the long channel micro-chips.2. Surface modification of COC micro-channels though photochemical grafting was evaluated. Since proper surfaces are critical for elimination of unspecific adsorption and maintaining good reproducibility, in this work, microchannel surfaces were modified by photo-initiated polymerization of acrylic acid, acrylamide, dimethylamino propyl methacrylamide, potassium salt and other monomers with benzophenone as a photo initiator to form hydrophilic layers. The extent of grafting and the resulting surface charges were evaluated by streaming potential measurement and other methods. The results demonstrated that microchannels could be successfully modified with the photo grafting.3. Trypsin digestion of a protein was realized with immobized trypsin onto the microchannel wall. Microfluidic operation consumes extremely low amount of sample, it is possible to perform enzymatic reaction inside microchannels with trace samples. In this work, teypsin was immobilized through either electrostatic adsorption or chemical anchoring onto the microchannels and used for trypsin digestion of bovine serum albumin inside microchannels. Capillary electrophoresis was used to monitoring the digestion process. The results indicated that trypsin digestion could be performed efficiently in microchannels with immobilized trypsin. This method is potential to be used in on-line trypsin digestion on microchips.