ABSTRACT
Due to the presence of surface amino groups, the nanoparticles can be directly conjugated to streptavidin (SA) molecules. Our previous works [15, 47, 50, 51] have shown that the bioactivity of the nanoparticlelabelled SA prepared by the direct conjugation method was rather low. To improve the low SA bioactivity of the nanoparticles, we established a bovine serum albumin (BSA) coating method to prepare nanoparticle-labelled SA. The BSA-coated nanoparticles were then used for binding to SA through the amino groups with glutaraldehyde. For details, refer to our earlier publications [48, 49]. One of the advantages of the BSA bridge method is that protein recognition sites are oriented away from the nanoparticle surface to ensure that they do not lose their ability to bind to a target. Reaction activity to biotin of the SA-BSA-nanoparticle conjugate was confirmed by using it for a time-resolved fluoroimmunoassay (TR-FIA) of human PSA.
