Figure 1.

Schematic representation of the MeLISA for the detection of biomarker. In this sandwich immunoassay, the polystyrene plate is covered with a capture antibody which could anchor the target biomarker. This coating step comprises the blocking procedure with bovine serum albumin to minimize nonspecific interactions. Serum sample with target antigen is added to the plate to allow the reaction between capture antibody and target antigen. Finally, the sandwich immunoassay is formed by the addition of the detection antibody that conjugated with silver nanoparticles. Introduction of hydrogen peroxide initiates the dissolution of AgNPs into silver ions, leading to a rapid aggregation of alkyne-functionalized AuNPs. The aggregation yields a distinct red-to-blue colour change in solution that can be read by eye or a compatible plate reader (for quantification).