Reshaping and LSPR tuning of Au nanostars in the presence of CTAB

Gold nanostars can easily undergo reshaping into spherical particles by simply adding a small amount of CTAB. Such reshaping can be understood in terms of Ostwald ripening involving dissolution of weakly bound surface atoms at areas with high convex curvature and re-deposition at concave areas. This process can be stopped at any time by adding silver ions, which block bromide and stabilize the surface. Because the localized surface plasmon resonance (LSPR) band of the nanostars colloid gradually changes during etching, stabilization of intermediate morphologies allows fine LSPR tuning, which can be exploited for plasmonic applications.