Nanoengineered Glancing Angle Deposition Thin Films for Ultrathin-Layer Chromatography.

摘要

Analytical separations are important methods of identifying and quantifying molecular compounds present in complex sample mixtures. These approaches are popular in biochemistry, medical diagnostics, quality control, and numerous other applications. In these techniques, constituent analytes are separated according to their characteristic physical and chemical properties. Planar chromatography analytical separations leverage the effects of these properties on competing interactions between the compounds, moving liquids, and stationary flat porous solids. Engineered solid-liquid interfaces can improve performance since these interactions occur at the nanoscale.;This dissertation studies UTLC layers produced using glancing angle deposition (GLAD). GLAD is an excellent platform for engineering nanostructured thin films of varied material, porosity, and architecture. It can achieve ~ 5 mum thick columnar morphologies well-suited for UTLC that are unattainable or impractical using other techniques. Unique anisotropic media exhibited channel features that strongly influenced analyte migration direction and velocity. Further control of chromatographic behaviours was achieved using post-deposition enhancements. Fluorocarbon reactive ion etching (RIE) selectively modifies film microstructure, increases porosity, and decreases the surface area over which analytes may interact. Atomic layer deposition (ALD) applies extremely thin < 10 nm conformal coatings that produce alternative chromatographic surface chemistries over GLAD UTLC film scaffolds. These investigations required invention of new instrumentation and analysis techniques since conventional planar chromatography equipment is unoptimized for miniaturized GLAD UTLC plates.;Approaches to fabricating, utilizing, characterizing, and enhancing nanoengineered GLAD UTLC media are considered in this thesis. The intriguing behaviours described within provide insight into the manner in which the microscopic features of GLAD films impact macroscopic development phenomena. These investigations simultaneously advanced both the capabilities of the UTLC planar chromatography technique and the understanding of GLAD nanostructured thin film materials.;Ultrathin-layer chromatography (UTLC) is a miniature form of planar chromatography in which sample analytes are carried by solvents that wick through < 10 mum thick solids with extraordinarily fine pores. The technique achieves fast separations (minutes) over short distances (millimetres to centimetres) with high sensitivity. The strong dependence of UTLC performance on layer microstructure motivates pursuit of new chromatographic media.