Size-Dependent Surface Enhanced Raman Scattering Activity\nof Plasmonic Nanorattles

Abstract

Surface\nenhanced Raman scattering (SERS) is considered to be a\nhighly attractive platform for chemical and biological sensing and\nmolecular bioimaging. Most of the SERS substrates and contrast agents\nrely on individual or lightly aggregated metal nanostructures that\neither offer limited enhancement or suffer from poor stability and\nreproducibility. We have recently demonstrated that plasmonic nanorattles,\nowing to the internal electromagnetic hotspots, offer significantly\nhigher SERS enhancement compared to their solid counterparts. In this\nwork, we investigate the size- and shape-dependent SERS activity of\nplasmonic nanorattles comprised of Au nanospheres and nanorods as\ncores and porous Au nanocubes and cuboids as shells. The SERS activity\nof Au nanorattles with spherical core was found to increase with increase\nin the edge length of the cubic shell. On the other hand, the SERS\nactivity of Au cuboid nanorattles with AuNR core was found to decrease\nwith increase in the size of the cuboid shell. Finite difference time\ndomain electromagnetic simulations show excellent agreement with our\nexperimental results. Comprehensive understanding of the size- and\nshape-dependent SERS activity of this novel class of nanostructures\ncan lead to the rational design and fabrication of highly efficient\nSERS substrates for chemical and biological sensing and ultrabright\ncontrast agents for SERS-based molecular bioimaging.