Advance in One-Pot Synthesis of Polymer-Coated Nanogold: Au(III)-Monomer Redox Reaction Initiates Radical...

Only a limited number of procedures truly qualify as one-pot synthesis for generating polymer-coated gold nanoparticles (AuNPs). The same applies to coated AuNPs that possess an additional functional feature enabling their direct application. This work presents a new one-pot method based on in situ chain-growth polymerization occurring simultaneously with the formation of nearly monodisperse coated AuNPs. The reaction proceeds between N,N-dimethylacrylamide (DMAA) and HAuCl₄ under alkaline conditions without requiring a polymerization initiator or reducing agent. Adjusting the DMAA/Au(III) molar ratio allows control over both nanoparticle diameter (7 to 16 nm) and the thickness of the polymer coating. During the growth of the gold cores and the polymer layer, a moiety generating an intense Surface-enhanced Raman spectroscopy (SERS) bioorthogonal signal is formed and anchored to the nanoparticle surface. SERS detects a strong signal in the region typical for a nitrogen-containing π-system, and X-ray photoelectron spectroscopy (XPS) further supports this observation. Repeated purification amplifies the relative intensity of SERS and XPS signals, indicating stable surface anchoring of the active moiety. The proposed reaction mechanism explains the formation of an isonitrile/carbene structure. Overall, the presented synthesis offers a simple route to prepare nearly monodisperse, multifunctional, and stable AuNPs as a potential nanotag platform.