Tuning Size and Sensing Properties in Colloidal Gold Nanostars

Gold nanostars are multibranched nanoparticles with sham tips, which display extremely interesting plasmonic properties but require optimization We present a systematic investigation of the influence of different parameters on the size, morphology, and monodispersity of Au nanostars obtained via seeded growth in concentrated solutions of poly(vinylpyirolidone) in N,N-dimethylformamide Controlled prereducnon of Au3+ to Au+ was found to influence monodispersity (narrower plasmon bands), while the [HAuCl4]/[seed] molar ratio significantly affects the morphology and tip plasmon resonance frequency We also varied the size of the seeds (2-30 nm) and found a deal influence on the final nanostar dimensions as well as on the number of spikes, while synthesis temperature notably affects the morphology of the particles, with more rounded morphologies formed above 60 degrees C This rounding effect allowed us to confirm the importance of sharp ups on the optical enhancing behavior of these nanoparticles in surface-enhanced raman scattering (SERS) Additionally, the sensitivity toward changes in the local refractive index was found to increase for larger nanostars. though lower Elgin e of merit (FOM) values were obtained because of the larger polydispersity