A novel amplification method was prepared based on dye-doped polymer particles for SPR signals originating from antigen-antibody (BSAanti-BSA) interactions. Coloring the particles enhances the change of SPR signals based on the change of the imaginary part of the refractive index. The signal amplification effect in the reflectance mode was 31-fold stronger compared to the effect obtained with white latex particles and the combined amplification effect due to the presence of polymer particles and the colorant was over 100-fold compared to non-amplified SPR signals originating from BSA-anti-BSA interactions. The amplification method based on the dye-doped particles is widely applicable for the analysis of antibody-antigen interactions and DNA interactions at low concentrations. q