Most core particles (𝜆 𝑚𝑎𝑥 = 529 nm) were successfully assembled with at least one satellite particle. Plasmonic coupling in the C/S particles is revealed by the intense plasmon coupling peak at 641 nm. This LSPR peak aligns well with the excitation wavelength of a HeNe laser (632.8 nm) often used for immunoSERS microscopy. Characterization by SEM corroborates the successful assembly of C/S particles and the presence of unbound satellite particles in accordance with the UV/Vis spectra. ). Au/Au C/S particles with 4-NTP-coated core particles are suitable candidates as immunoSERS labels since they are SERS-active at the single-particle level. Single-particle brightness is achieved by placing Raman reporter molecules, such as 4-NTP, in the narrow gaps between core and satellite particles. For their use as nanotags, SERS-inactive monomeric AuNP need to be removed to avoid falsenegative results. In this study, we apply centrifugation and asymmetric flow field flow fractionation as separation methods and compare the separation quality.