Fabrication and characterization of tunable plasmonic nanodomes

Surface-enhanced Raman scattering (SERS) is a powerful technique used for characterization of biological and non-biological molecules and structures. Since plasmonic properties of the nanomaterials used as SERS substrates is one of the most important properties in SERS experiments, plasmonic properties which can be tunable is crucial in SERS studies. SERS enhancement can be maximized by controlling of plasmonic properties of the nanomaterials. General aim of this study is fabrication of three-dimensional nanodomes having tunable plasmonic properties using simple and cheap methods, characterization of nanodomes, and to investigate their SERS activities. In this study, nanodomes composed of only plasmonic metals will be fabricated using cheaper, simpler methods and without adhesion layer and used for the bioanalytical applications based on SERS. Convective-assembly method is used for the uniform deposition of latex particles on a glass slide. For this purpose, nanosphere lithography and soft lithography will be used together to fabricate nanovoids on the Polydimethylsiloxane (PDMS) surface which will be used as template for the fabrication of plasmonic nanodomes. Plasmonic Ag nanodomes (AgNDs) having different height and diameter will be obtained by filling of the fabricated nanovoids having different depth and diameter depending on the sizes of the used latex particles with electrochemical coating which is simpler and cheaper. The structural properties of all fabricated AgNDs are characterized using scanning electron microscopy (SEM) and atomic force microscopy (AFM). The fabricated AgNDs are incubated in an ethanolic solution of ATP (1mM) for an hour to test for the activity of the SERS activities. The finite difference time domain (FDTD) method is used for the plasmonic properties calculation of the AgNDs. To explore the plasmonic properties (the surface plasmons wavelength and the electromagnetic field magnitude) of AgNDs depending on the AgNDs diameters and heights, FDTD simulation are performed. The maximum enhancement is obtained when 1000 nm latex particles are used for the fabrication of AgNDs. The fabricated AgNDs having highest SERS activity offers great promise for their use in SERS-based sensing and characterization of biological and chemical structures. Keywords: Nanodome, SERS, Plasmonics, Electrochemical Coating, Silver, PDMS