Ultrasensitive SEIRA detection using gold nanobipyramids: Toward efficient multimodal immunosensor

Surface enhanced spectroscopies are proven to be highly efficient in biosensing applications. Their im-plementation as analytical tools in the detection of medically relevant target analytes demonstrated their ability to considerably decrease the minimum detected analyte concentration, thus showing improved sensitivity compared to commercially available detection kits. In this work, we propose the employ-ment of Surface Enhanced Infrared Absorption (SEIRA), a less exploited analysis tool, for the efficient, specific, and ultrasensitive detection of the biotin-streptavidin recognition interaction using a gold nano-bipyramid-based (AuBPs) immunosensor. The unique optical properties of the AuBPs, such as tunability of the LSPR band ranging from the visible to NIR regions of the spectrum, great absorption capabili-ties and locally enhanced electromagnetic field at their tips and edges, enable an improved efficiency of the IR absorption of the target analytes. To the as-synthesized AuBPs, a chemically formed p-ATP@biotin recognition element was grafted due to the strong Au-S interaction, followed by the exposure of the ob-tained biotinylated nanosystem to the streptavidin target analyte. FT-IR experimental measurements as well as theoretical simulations confirm both the successful grafting of the p-ATP@biotin onto the Au sur-face and successful capture of the target streptavidin protein. A limit of detection of 10(-12) M streptavidin concentration was determined, thus standing as a proof-of-concept for the development of efficient ultrasensitive SEIRA biosensing devices for more complex biologically relevant applications. (C) 2021 Elsevier B.V. All rights reserved.

Automated summary

The study proposes the use of Surface Enhanced Infrared Absorption technology for efficient, specific, and ultrasensitive detection of biotin-streptavidin recognition interaction using a gold nano-bipyramid-based immunosensor. Successful grafting of p-ATP@biotin onto the gold surface and successful capture of the target streptavidin protein were confirmed through FT-IR experimental measurements and theoretical simulations. The development shows promise for efficient ultrasensitive SEIRA biosensing devices for more complex biologically relevant applications.