In order to confirm that our immobilization strategy actually offers advantages in biological assays, we performed a negative control using 80 nm SiGNPs coated with copoly azide 4%, further functionalized with unmodified streptavidin. Lacking DBCOmodification, streptavidin can only adsorb on the surface of nanoparticles. We used these AuNPs with the same experimental procedure (see Supplementary material for details).