Hollow Gold Nanoshells\nfor Sensitive 2D Plasmonic\nSensors

Abstract

The interaction of incident light with noble metal nanoparticles\nengenders a fascinating phenomenon known as localized surface plasmon\nresonance (LSPR). This results in the presence of single or multiple\nintense absorption bands in the visible to near-infrared spectral\nrange whose position is affected by the refractive index of the surrounding\nmedium. In this comprehensive study, we thoroughly investigated the\nexperimental parameters governing the size, aspect ratio, and optical\nproperties of hollow gold nanoshells (hAuNSs) synthesized through\nthe galvanic exchange of cobalt-based nanospheres. Subsequently, we\nrigorously determined both the empirical and the theoretical refractive\nindex sensitivity (RIS) and figure of merit (FoM) of these engineered\nnanostructures. Notably, hAuNS with an external diameter of 98 nm\nand a shell thickness of 13 nm demonstrated a noteworthy RIS of 360\nnm/RIU and an FoM of 2.0 in solution. In contrast, solid gold nanospheres\n(sAuNSs) of a similar diameter exhibited a significantly lower RIS\nof 136 nm/RIU. Following the transfer of both of these nanostructures\nonto glass slides for the development of LSPR sensors, it was intriguing\nto note that the RIS and FoM remained largely unaffected. These findings\nunderscore the potential of these plasmonic nanoparticles as promising\ncandidates for the design of sensitive solid-phase LSPR sensing devices.