Exploiting the Unique Plasmonic Phenomenon of Metallic Nanostructures for Sensing and Biosensing Applications
Real-time, accurate sensing promoted by analytical sensors is extremely important for advances in drug discovery, disease diagnosis and for studying biological systems. In particular, label-free surface plasmon resonance (SPR)-based sensing, promoted by metallic nanostructures which can couple incident light with free electrons in the metal layer, have been widely used commercially. However, current commercial SPR systems suffer from high cost, low-throughput and have a high footprint making them unusable for point-of care applications. In this dissertation, a new SPR biosensor based on plasmonic crossed surface relief gratings (CSRGs) is demonstrated. Miniaturized optical biosensing platforms based on CSRGs and nanohole arrays (NHAs) are employed for sensing of molecular interactions in a quantitative manner. The CSRGs- and NHAs- based SPR devices measure the transmission of the normally incident light with the help of a collinear optical setup consisting of off-the-shelf electronics and optical components. The devices allow for the nanomolar detection limit of molecules in analyte-analyte binding kinetic assays and allow for the detection of pathogenic bacteria in complex biological matrices, in clinically relevant concentrations. Additionally, newly developed nanofabrication method involving template-stripping of CSRGs enable the production of large-area metallic nanogratings in an inexpensive and high-throughput fashion, allowing for chemical sensing of contaminant via surface enhanced Raman spectroscopy. The work presented in this dissertation can give rise to novel miniaturized and portable sensing and biosensing platform with improved performance and multi-disciplinary applications.