Pacific Rim Symposium on Surfaces, Coatings and Interfaces (PacSurf 2018)
    Nanomaterials Tuesday Sessions
       Session NM-TuM

Paper NM-TuM9
A Reproducible Assay for Versatile Biosensing by Surface-enhanced Raman Scattering

Tuesday, December 4, 2018, 10:40 am, Room Naupaka Salon 5

Session: Nanofabrication and Nanodevices
Presenter: Paul Stoddart, Swinburne University of Technology, Australia
Authors: M. Al Mamun, Swinburne University of Technology, Australia
N.A. Cole, Swinburne University of Technology, Australia
S. Juodkazis, Swinburne University of Technology, Australia
P. Stoddart, Swinburne University of Technology, Australia
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Over the forty years since its discovery, surface-enhanced Raman scattering (SERS) has attracted significant attention as a sensitive technique for surface analysis. The high sensitivity of SERS and compatibility with microfluidic techniques makes it an attractive option for point-of-care sensing applications. However, we are not aware of any routine analytical applications of SERS that have emerged to date. In particular, SERS substrates are subject to variability due to high sensitivity to nanometre scale structure, complex surface interactions in real-world samples, susceptibility to environmental contamination, and a limited substrate shelf life. Here we report a versatile biosensing technique, where the target analyte is labelled with biotin, and is in turn reliably captured by a streptavidin-coated substrate. Subsequent exposure to an excess of biotin saturates the remaining binding sites and provides an internal intensity reference to assist quantification. Once the analyte has been immobilized via the biotin-streptavidin interaction, a photochemical reduction process is used to deposit silver nanoparticles over the surface. This generates a SERS substrate on demand, with high sensitivity and high reproducibility, while protecting the surface from environmental contamination. Using atto-488 as a model analyte, it has been shown that the process can deliver nanomolar sensitivity. The fluorescent emission of the atto-488 was used to confirm the surface immobilization, but is quenched by the presence of the metal coating in the SERS measurements. With appropriate extensions to an integrated microfluidic platform, the developed technique has the potential to be used to detect a wide range of small molecule targets of interest in body fluids .