Plasmonic Core-Satellite Assemblies as Highly Sensitive Refractive Index Sensors

Highly sensitive and spectrally tunable plasmonic nanostructures are of great demand for applications such as SERS and parallel biosensing. However, there is a lack of such nanostructures for the midvisible spectral regions as most available chemically stable nanostructures offer high sensitivity in the red to far red spectrum. In this work, we report the assembly of highly sensitive nanoparticle structures using a hydroxylarnine mediated core-satellite assembly of 20 nm gold nanopartide satellites onto 60 nm spherical gold cores. The average number of satellites allows tuning the plasmon resonance wavelength from 543 to 575 nm. The core-satellite nanostructures are stable in pH ranges from 6 to 9 and show about 2-fold higher plasmonic sensitivity than similar sized gold nanospheres.