Plasmonic refractive index sensitivity of tetrapod gold nanostars: tuning the branch length and protein layer

The refractive index sensitivity of the tetrapod nanostars was studied. The extinction spectra and environmental refractive index sensitivity of the tetrapod gold nanostars with different branch lengths were calculated, and it was found that the environmental refractive index sensitivity of the tetrapod gold nanostars with longer branches was higher. The environmental refractive index sensitivity of the tetrapod gold nanostar coated with a protein layer is calculated. The greater the dielectric constant of the protein layer, the smaller the influence of the thickness of the protein layer on the refractive index sensitivity of the tetrapod gold nanostar, but at the same time the tetrapod nanostars can achieve higher environmental refractive index sensitivity. These sensing properties of the tetrapod gold nanostars provide potential for nano-optical biosensing research and provide theoretical guidance for the design of LSPR-based biosensors and SERS applications. Graphic abstract: [Figure not available: see fulltext.]