Gold-silver nanoboxes: a new nanostructure for surface-enhanced Raman spectroscopy

<p dir="ltr">Surface-enhanced Raman spectroscopy (SERS) is a non-destructive technique that provides ultra-sensitive, highly specific, and photostable molecular structure information for trace analysis and multi-component profiling in biosensing applications. In this thesis, three sizes of gold-silver nanoboxes (NBs) were synthesized using a one-pot free-template method. Then, the NBs were characterised by the unique properties of hollow, cube-shaped alloy nanostructure with a large surface area using various analytical techniques, including ultraviolet-visible spectroscopy, electron microscopy, and Raman spectroscopy. Out of five nanoparticles investigated, including spherical gold and silver nanoparticles, the 75 nm NBs displayed the highest SERS performance. These optimised 75 nm NBs were bound with four different thiol molecules, each displaying distinct Raman fingerprints of the molecules on the NB surface using three laser excitations at 532 nm, 633 nm, and 785 nm. The simulation results confirmed the experimental findings, indicating the superior SERS enhancement of the 75 nm NBs compared to other nanoparticles and illustrating the impact of different lasers on SERS intensity. The 75 nm NBs were also coated with a silica shell to improve stability and dual-analysis using fluorescence and SERS. This thesis reveals the potential of NBs for sensitive and specific cancer biomarker-sensing applications using SERS.</p>