MP24: Conjugated Nanoparticles based Enhancement for High-throughput Protein Detection via Surface Plasmon Resonance Imaging

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Ying Liu, Abdennour Abbas, Quan Cheng
Department of Chemistry, University of California, Riverside, California 92521

  Sensitive monitoring of biological interactions in a multiplexed array format has numerous advantages. Surface plasmon resonance imaging (SPRi), an optical technique allowing label-free detection of thin organic films, has emerged as an excellent tool to provide real-time analysis for array-based methodologies. However, current microarray based SPRi methods have limited detection sensitivity. We report here an effective SPRi signal amplification method using conjugated nanoparticles. Cholera toxin (CT) is immobilized on SPRi gold array film to form an protein array where the spare area is blocked by bovine serum albumin (BSA). Biotinylated antibody CT is captured to CT surface through flow cell injection and in-line incubation. SPRi signal amplification is achieved via consecutive binding of two different kinds of nanoparticles: gold nanoparticle (GNP) and magnetic iron oxide nanopaticle (Fe3O4). The former is functionalized with biotin tag, while the latter with streptavidin tag. Fe3O4-streptavidin sufficiently filled the gap area between the building blocks GNP-biotin, significantly enhance SPR signal due to its high refractive index and stacking density. Control experiments are conducted in the absence of CT and from direct binding of Fe3O4-streptavidin only. The high specificity of immune reaction eliminates cross reaction and allows adaptation of this strategy for simultaneously in situ multiplexed detection, opening new avenues for sensitive high-throughput detection of DNA, RNA, and peptides.

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