High performance immunochromatographic assay combined with surface enhanced Raman spectroscopy

We present a novel biosensor concept achieved by integrating a widely used lateral-flow immunochromatography (LF-ICA) system with a highly sensitive surface enhanced Raman spectroscopy (SERS) technique to overcome the lack of sensitivity of the conventional LF-ICA that employs gold nanoparticle (AuNP) as a tracer. The SERS phenomena can be produced from hotspot formation between enlarged AuNPs labeled with Raman reporters by applying a simple silver intensifying process, resulting in a significant Raman signal enhancement. Several major factors that influence the analytical performance of the system such as laser power, integration time, nanoparticle size, and silver intensification time were experimentally optimized to maximize Raman intensity. Consequently, compared with the conventional LF-ICA, this new method shows approximately 1000-fold increase in detection sensitivity compared to the FluB assay, enabling detection of extremely low concentration of the analyte without additional complicated steps.