Tuning the Synthesis and Stabilization of Gold Nanorods for Enhanced LSPR Sensor Chip Performance

Abstract

Plasmonic nanorods exhibit unique optical properties due to their ability to support localized surface plasmon resonances (LSPR). These nanorods are highly valued for applications in sensing, imaging, and medical therapies because of their tunable optical behavior and strong electromagnetic field enhancement. In this study, a seed-mediated approach has been utilized to synthesize and purify gold nanorods (GNRs), with a focus on their integration in the LSPR sensor chips. The synthesis has begun with the preparation of small gold nanoparticles as seeds, followed by the growth of nanorods in a carefully controlled environment. UV-visible spectroscopy has confirmed the formation of GNRs, revealing two plasmonic peaks, with the transverse peak at 523 nm and the longitudinal peak at 800 nm after 24 hours of aging. Further, self-assembled monolayer of the GNRs on glass substrate has been achieved using a thiol-functionalized linker, 3- mercaptopropyltrimethoxysilane (MPTMS), and ionic strength modulation with NaCl. For optimal stabilization and alignment of the nanorods on the glass substrate, the ideal incubation time for the glass substrates in the colloidal gold nanoparticle solution has determined to be 24 hours. This duration has made the most effective configuration of the LSPR sensor chip, with improved stability and sensitivity for plasmonic applications.