Near-field interaction effects in colloidal Au-CeYTbF$_{3}$ nanoclusters in plasmonic immunoanalysis

In this paper, we study the effects of plasmonic enhancement of spontaneous emission in colloidal nanoclusters consisting of Au nanoparticles and CeYTbF$_{3}$ phosphor. Based on numerical simulation of various configurations of Au nanoparticles coated with polyethyleneimine, we analyzed the dependence of plasmonic resonances position on their number and distribution. The results showed that optimal nanoparticle configurations significantly enhance luminescence in the desired region of the visible spectrum, which opens up new possibilities for the development of highly sensitive nanosensors. At the same time, nanoclusters located on a Au substrate demonstrate a lower luminescence enhancement coefficient, while having a more inhomogeneous distribution of the optical near field. The results obtained reveal the dependence of the luminescence enhancement coefficient on the spatial distribution and coordination number of plasmonic nanoparticles in a nanocluster. This study contributes to the understanding of plasmonic interaction mechanisms and its applications in optical immunoassay and biomedical technologies.