| Abstract
| - A rapid, sensitive format for immunosorbent assays hasbeen developed to meet the increasing levels of performance (i.e., reduction of incubation times and detectionlimits) demanded in the medical, veterinary, and bioterrorism prevention arenas. This paper introduces theconcept of a rotating capture substrate as a facile meansto increase the flux of antigen and label to the solid-phasesurface and thereby reduce assay time. To this end, asandwich-type assay is carried out that couples thespecificity of antibody−antigen interactions with the highsensitivity of surface-enhanced Raman scattering detection. To investigate this strategy, polyclonal anti-rabbit IgGwas immobilized on a gold capture substrate via a thiolatecoupling agent. The capture substrate, capable of controlled rotation, was then immersed in a sample solutioncontaining rabbit IgG, which served as a model analyte.After binding the target IgG, the substrates were immersed and rotated in an extrinsic Raman label (ERL)labeling solution, which is composed of gold nanoparticles(60 nm) coated with an aromatic moiety as the Ramanscatterer and an antibody as the biospecific recognitionelement. The effect of substrate rotation on both theantigen binding and ERL labeling steps was investigated.Implementation of optimized rotation conditions resultedin the reduction of assay times from 24 h to 25 min anda 10-fold improvement in the limit of detection. Finally,the developed protocol was applied to the detection ofrabbit IgG suspended in goat serum, which served toassess performance in a biological matrix.
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