In this thesis, the successful fabrication of 3D-printed microfluidic devices will be discussed. Fabrication is performed with a low-cost commercially available stereolithographic 3D printer utilizing a custom PEGDA resin formulation tailored for low non-specific protein adsorption based on my colleagues' work [Rogers et al., Anal. Chem. 83, 6418 (2011)]. Horizontal microfluidic channels with designed rectangular cross sectional dimensions as small as 300 um wide and 150 um tall are printed with 100% yield, as are cylindrical vertical microfluidic channels with 300 um designed (334 um actual) diameters. Moreover, two different resins developed by our group are utilized in the process of 3D-printing which is the novel aspect about this thesis since other groups have not done research on this aspect of 3D-printing.

Several novel polymer monoliths for the analysis of peptides and proteins were synthesized using polyethylene glycol diacrylate (PEGDA) as crosslinker. Photo-initiated copolymerization of polyethylene glycol methyl ether acrylate and PEGDA yielded an inert monolith that could be used for size exclusion liquid chromatography of peptides and proteins. This macroscopically uniform monolith did not shrink or swell in either water or tetrahydrofuran. More importantly, it was found to resist adsorption of both acidic and basic proteins in aqueous buffer without any organic solvent additives. A strong cation-exchange polymer monolith was synthesized by copolymerization of 2-acrylamido-2-methyl-1-propanesulfonic acid (AMPS) and PEGDA. A ternary porogen (water, methanol and ethyl ether) was found suitable to prepare a flow-through monolith with moderate pressure drop in aqueous buffer. The resulting monolith showed excellent ion exchange capillary liquid chromatography of peptides using a simple salt gradient. Extremely narrow peaks were obtained for the analysis of synthetic peptides, natural peptides and a protein digest. A peak capacity of 179 was achieved. Although the poly(AMPS) monolith demonstrated extraordinary performance, one main drawback of this monolith was its relatively strong hydrophobicity. A decrease in hydrophobicity was achieved by using more hydrophilic monomers (e.g., sulfoethyl methacrylate or vinyl sulfonic acid). The most hydrophilic poly(vinyl sulfonic acid) monolith provided high resolution cation-exchange liquid chromatography of protein standards and lipoproteins. Use of the new PEGDA biocompatible crosslinker over the conventional ethylene glycol dimethacrylate crosslinker for the preparation of polymer monoliths was found to be advantageous for the analysis of biological compounds in several chromatography modes.