| This dissertation demonstrates a series of optical and microfluidic techniques to provide a platform for the analysis of minute biological samples encapsulated in aqueous droplets. First, cell microsurgery is performed with optical tweezers to isolate single organelles from living cells. The primary mechanism of cell death from microsurgery was examined by systematically studying the long-term viability of CHO-M1, NG108-15, and ES-D3 cell lines after the removal of a single organelle. Additionally, single cells and organelles are compartmentalized into aqueous droplets that provide an isolated container allowing for sensitive enzymatic assays without loss to dilution.;Secondly, a method for the analysis of the contents of single femtoliter-volume aqueous droplets by capillary electrophoresis (CE) coupled with laser-induced fluorescence is presented. Here, a single droplet was formed using a T-channel and then transported to an adjoining CE channel that was physically isolated from the other microchannels by an immiscible boundary. Since droplet generation in channels requires hydrophobic surfaces, the advantages to using all hydrophobic channels versus channel systems with patterned hydrophobic and hydrophilic regions are also investigated.;Next, the integration of CE with electroosmotic flow (EOF) driven droplet generation, such that the molecular components or peaks separated by CE are compartmentalized in a series of droplets is demonstrated. Following CE separation and droplet compartmentalization, the droplet-confined peaks can either be docked and studied on-chip or removed off-chip for additional separation or analysis. For on-chip droplet docking, a design in which the locations of the docked droplets encoded the positions of the separated peaks is demonstrated. For off-chip droplet analysis, the use of micellular electrokinetic chromatography to resolve a racemic mixture of D/L glutamate is shown. The dynamics of EOF-induced droplet formation and the EOF flow profile during downstream droplet generation are characterized.;Lastly, the compartmentalization of CE separations performed on a fused silica capillary into aqueous droplets is demonstrated. Here, high resolution separations are first performed in a fused silica capillary that has been integrated into a droplet-based microfluidic chip. The hybrid device presented here improves upon poor separation efficiency in standard microfludics, yet still allows for complex microfluidic handling. |
