There has been considerable progress in the development of micro-fabricated systems for the field of chemical and
biological sciences. Much development has been driven by the need of miniaturized systems that allow cost-effective
and rapid processing of samples at the point of need. In this work, we investigate the application practicality of Objet
Eden500V<sup>TM</sup>Polyjet as a rapid and economical tool for multi-level microfluidic device rapid prototyping. The Polyjet is
a commercial system that utilizes ink-jet technology to print 3-dimensional structures with photopolymer materials. The
reproducing capability of the Polyjet system in term of lateral and vertical resolutions, aspect ratio and smoothness of
fabricated structures are investigated. In addition, the capability of the Polyjet is demonstrated by fabricating three
different devices including: 1) multi-level microfluidic chip for two-step gene synthesis, 2) a fluidic component for
micro/macro fluidic interfacing, and 3) PDMS-based microlens.
Herein we report three novel methods which utilize chemical conjugated magnetic beads to purify synthetic gene from its synthesis solution and prepare the synthesized gene in suitable buffer for downstream applications. Silica-coated magnetic beads are applied for non-specific DNA purification to remove short oligonucleotides and monomers. Streptavidin conjugated magnetic beads and (dT)<sub>25</sub> Oligo immobilized magnetic beads are introduced for specific DNA extraction. The performances of these methods are investigated and compared using gel electrophoresis. The optimal conditions for enhancing the extraction efficiency are discussed. In addition, the approach to integrate these solid-phase purification methods into microfluidic devices is presented.
We have developed a new synthetic method for producing high-quality quantum dots (QDs) in aqueous solution for biological imaging applications. The glutathione-capped CdTe, ZnSe and Zn<sub>1-x</sub>Cd<sub>x</sub>Se alloyed QDs derived are tunable in fluorescence emissions between 360 nm and 700 nm. They show high quantum yields (QYs) of up to 50%, with narrow bandwidths of 19-55 nm. The synthesis of glutathione-capped QDs is simple and cost-effective compared to the conventional organometallic approaches. It can be easily scaled up for the commercial production of alloyed nanocrystals of various compositions. We have also demonstrated the fabrication of magnetic quantum dots (MQDs) through a seed-mediated approach. The formation and assembly of these bifunctional nanocomposites have been elucidated by high-resolution transmission electron microscopy (HRTEM). The MQDs exhibit superparamagnetism and tunable emissions characteristic of the components in this hybrid system. We have created biocompatible silica-coated MQDs that effectively target the cell membranes.