Chemical Synthesis in Elastomer-Based Integrated Microfluidics

There is wide interest in using the unique properties of microfluidic environments for the production of fine chemicals and pharmaceuticals. Compared to bench top synthesis, microfluidic systems engender the significant advantage of superior control of chemical state functions. The ability to tune reagent concentration, reaction temperature, mixing time, and residence time allows reactions to run more efficiently thus generating products of higher yield and purity. While several microfluidic platforms are actively developed in both academic and industrial laboratories, vast majority are based in rigid materials and have only demonstrated improvements in yield for single reaction steps. Multilayer Soft Lithography has already found much use in the biological field. For example, several complex devices based upon functional modules have been developed for protein crystallography, nucleic acid processing, FACS, enzyme screening tools, and PCR. Because of the many similarities between operations in organic synthesis and biochemistry, there is widespread interest in extending these newfound successes in the realm of biology to the realm of automated chemical synthesis. This thesis focuses on the application of Multilayer Soft Lithography to the development and adaptation of microfluidic tools for chemical synthesis. The first successful demonstration of multistep organic synthesis in integrated microfluidics was the production of a molecular image probe, 2-deoxy-2-[18F]fluoro-d-glucose. The nanogram level dosage for imaging probes makes them attractive candidates for small scale synthesis of microfluidics. The reduced synthesis time achieved by using a microfluidic device is especially important because of the relatively short half-life of the radioactive fluoride. While PDMS remains the material of choice for devices in biological applications, its incompatibility with many nonpolar organic solvents limits the types of reactions that can be performed with it. Through collaboration with Joseph DeSimone’s group at the University of North Carolina at Chapel Hill, a suitable substitute for PDMS was found in perfluoropolyethers (PFPE). A solvent-resistant integrated microfluidic device was developed for solid-phase oligonucleotide synthesis using conventional phosphoramidite chemistry. To confirm that the microfluidic platform in development can indeed become a valuable tool in the field of synthetic biology, a 16 column parallel oligonucleotide synthesizer was manufactured that is capable of producing 16 distinct sequences up to 40 bases in length to be used in gene assembly. Successful construction of a gene fragment was completed from a mixture of unpurified and unamplified oligonucleotides synthesized on the device.