Molecular Sensing Using Aggregation of Gold Nanoparticles

Gold nanoparticles (AuNPs) have emerged as powerful tools in the molecular sensing field for developing highly sensitive and selective molecular detection methods due to their unique properties, such as optical features and ease of surface modification. The core principle of AuNP-based sensors involves target molecule-induced aggregation, dispersion, or assembly of AuNPs through specific interactions with target molecules. These interactions cause changes in optical or electrochemical properties, which can be monitored through visible color shifts, surface-enhanced Raman scattering (SERS) signals, electrochemical techniques, and changes in scattering intensity. This review aims to highlight molecular detection strategies focusing on surface modification and aggregation mechanisms of AuNPs. It also introduces representative applications using colorimetric methods, SERS, electrochemical assays, and dark-field microscopy.