Colorimetric assays typically rely on a color change caused by a chemical reaction between the analyte and a chromogenic reagent. In nanotechnology, nanoparticles such as gold nanoparticles (AuNPs) and silver nanoparticles (AgNPs) are often used due to their size-dependent optical properties, such as localized surface plasmon resonance (LSPR). When these nanoparticles aggregate or disperse, they exhibit distinct color changes that can be easily monitored.
