I will present work from my Ph.D. and post doctoral research which has focused on creating advanced polymeric materials and microfluidic devices to obtain sample in answer out capabilities for biomedical diagnostics and the chemical exploration of the solar system.
In order for micro total analytical systems to realize full maturity, the advancement of soft polymeric materials used for purification, concentration, and analysis must advance beyond current levels and be fundamentally well characterized. Here, I present the synthesis and characterization of families of poly(acrylamide-co-alkylacrylamide) that accomplish on-chip purification of DNA from protein and advance bioanalytical separations. Hydrophobic alkylacrylamide monomers were synthesized and subsequent families of poly(acrylamide-co-alkylacrylamide) were polymerized via “micellar” and free-radical synthesis. Monomers and copolymers were characterized by techniques such as: HPLC, gel-permeation chromatography, 1H NMR, dynamic light scattering, polymer solution rheology, and differential scanning calorimetry. Remarkably, the inclusion of < 1% of the alkylacrylamide in the copolymer leads to a significant improvement in separation performance and provides enough adsorption sites to enable DNA purification. Along with the traditional polymer characterization techniques, electrophoresis of DNA was visualized via single-molecule video microscopy. DNA migration physics were studied in both standard polymer and the copolymers systems where a previously unkown mechanism was discovered. The transitions in separation modality were correlated to polymer overlap and entanglement concentrations.
In my post doctoral work, I developed microfabricated biochemical analysis systems for in situ detection of organic biomarkers of extant or extinct life on Mars and other solar system bodies as a part of the ExoMars mission on the European Space Agency. Ultra-sensitive (sub pptr) pseudo-2D analysis techniques were created for amino acids and validated on Martian analog samples (e.g. meteorite, Atacama Desert) and a simulant of an astrochemistry reaction producing complex organics including amino acids and dipeptides. Derivatization and separation chemistries were developed for analysis of aldehydes, ketones, carboxylic acids, and polycyclic aromatic hydrocarbons. Advances in analytical protocols and buffer chemistry improved the robustness of the CE system when analyzing highly saline and acidic samples as found in Rio Tinto sediments and Saline Valley brine samples. Validation of these methods is shown through the analysis of Martian analog samples (e.g. Murchison Meteorite, Atacama Desert), an environmental sample for PAH analysis, and a simulant of an astrochemistry reaction producing complex organics such as amino acids and dipeptides. Automation and integration of on-chip functionality was explored through a multichannel microchip electrophoresis system with a common sample bus and devices incorporating metering, mixing, serial dilutions and reaction networks.