| This thesis research explored the use of: (1) a flow-through configuration immunoassay and (2) colorimetric-solid phase extraction (C-SPE) for the rapid, sensitive detection of analytes. Surface-enhanced Raman scattering (SERS) and diffuse reflectance spectroscopy (DRS) were employed for readout. First, the effectiveness of the production of extrinsic Raman labels (ERL) used in SERS-based immunoassays was assessed in terms of the reproducibility of surface modification. ERLs were then incorporated into the detection of human IgG using a flow-through configuration with gold-coated aluminum oxide membranes (Au-AOM) as nanoporous capture substrates. Importantly, the use of a flow-through configuration dramatically decreases the incubation time necessary for analysis without sacrificing sensitivity and little sacrifice on the limit of detection (LOD) (2 vs. 13 ng/mL). The increase in immunoassay sensitivity under flow is discussed in terms of non-equilibrium antigen-antibody binding. The second part of this thesis describes the development of a C-SPE method focused on the sensitive, rapid, cost-effective, and facile detection of arsenite (As(III)) at low microgram per liter levels. This last chapter therefore expanded the capabilities of C-SPE in detecting important environmental contaminants. |
