Abstract
The technique of plasmonic ELISA is utilised here to detect the HIV-1 protein gp120 with the ultralow limit of detection of 8 × 10−20 M (10−17 g mL−1) in an independent laboratory. It was corroborated that changes in the concentration of hydrogen peroxide as small as 0.05 μM could lead to nanoparticle solutions of completely different tonality.