Innovative Plasmonic Platforms for Advanced Molecular Sensing

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The present research proposal seeks to focus on an area of nanotechnology termed plasmonics. The field of plasmonics relies on the unique optical and electronic effects observed when certain nanoscale metals, such as the coinage metals, interact with incident electric fields, such as the electric field component of light. Such interaction generates what are termed surface plasmons, which can be either confined to the surface or can propagate along the surface of a nanometal, depending on its size and dimensions. These surface plasmons have remarkable attributes, most notably the ability to harvest and manipulate light at the nanoscale, leading to highly sensitive chemical sensing and unprecedented future developments in near-field optical microscopy and plasmonic circuitry. Such advanced materials have an enormous range of possible and demonstrated applications, ranging from enhanced solar-energy conversion to superlenses and optical cloaking. The research program outlined herein revolves around three main themes related to advanced molecular sensing using innovative plasmonic platforms: (i) enhanced sensitivity (ii) improved selectivity and (iii) future sustainability; these areas are summarized below.(i) Enhanced sensitivity. While theoretical studies have demonstrated that the excellent light-manipulation of plasmonic nanoparticles should allow for single molecule level detection; routine evidence of such detection limits is lacking. A solution to this problem lies in the ability to not only fabricate nanoparticles with excellent monodispersity in terms of size and shape, but also in the ability to fabricate assemblies of such structures in a desired configuration over large surface areas with minimal cost. Our approach to overcome these issues will be to explore several strategies including layer-by-layer deposition, bioscaffolding and plasmonic metamolecular arrays for creating novel plasmonic platforms. (ii) Enhanced selectivity. One problem that continually plagues advances in plasmonic sensing is the non-specific interaction of non-target analytes with the sensor surface. Our approach will be to expand on our exploratory work in the field of aptasensors for target analyte detection. In addition, we will explore the extent to which electrochemical surface enhanced Raman spectroscopy (SERS) can be used to enhance selectivity. iii) Future sustainability. Current plasmonic metals, such as Au and Ag, suffer from the disadvantage of high cost, especially for gold, as well as limited long term availability, especially for silver. As part of this program, we plan to explore the use of copper and aluminum nanoparticles for plasmonic applications. Issues associated with the synthesis and stability of such nanostructures will be circumvented using methods such as ionic liquid stabilized nanoparticle synthesis and electrochemical deposition.