Here, a high sensitive method for biomarker identification according to nanostructure, using enzyme-linked immunosorbent assays (ELISAs), called Nano-ELISA, was presented. Different shapes of gold nanostructures (star and sphere; GNSs and GNPs) with a particle size of 40 nm for sphere particles were altered with a monoclonal antibody (Ab) as a detector Ab. To amplify the optical signal, gold nanostructures were employed as carriers of the signaling specific antibody against insulin growth factor binding protein- 3 (IGFBP-3). The substrate was catalytically oxidized by the Horseradish Peroxidase (HRP) conjugated gold nanostructure, and HRP also enhanced the optical signals, reflecting the amount of the targeting IGFBP-3. In comparison to the classical ELISA procedure, this assay using gold nanostructure as an enhancer, have higher sensitivity and shorter testing time, in the spectrum between 0.05 ng/mL and 30 ng/mL. Gold nanostar based ELISA assay (GNS-based ELISA) have lower LOD, signal amplification potency, and higher specificity and sensitivity, compared to gold nanoparticles based ELISA (GNP- based ELISA) assay.
