Thiol‐Functionalized IGEPAL® Surfactants as Novel Fluorescent Ligands for the Silica Coating of Gold Nanoparticles

A synthesized thiol‐functionalized non‐ionic surfactant based on the IGEPAL® (polyoxyethylene(5) nonyl phenyl ether) structure, has been used to replace citrate ions from the surface of gold nanoparticles with 13.5 nm diameters. Upon IGEPAL®‐type stabilization in water, the nanoparticles were transferred to ethanol, where a layer of silica was efficiently grown on the nanocrystal surface through the conventional Stöber approach. This method allows fine control over the silica thickness, showing uniform and homogeneous core‐shell nanoparticles. Additionally, the luminescent properties of the IGEPAL® surfactant allow the versatile preparation of robust fluorescent nanoparticles with multiplexing potential as simultaneous plasmonic and fluorescence probes.