High Recognition of Isomer-Stabilized Gold Nanoparticles through Matrix Imprinting

The development ofhighly selective probes for nanoparticles isrequired due to their nanotoxicity. The latter strongly depends onthe size, structure, and interfacial properties of the nanoparticles.Here, we demonstrate that a simple approach for the selective detectionof Au nanoparticles that differ in their capping agent shows veryhigh promise. Specifically, gold nanoparticles stabilized by eachof the three different isomers of mercaptobenzoic acid (MBA) wereimprinted in a soft matrix by adsorption of the nanoparticles, followedby filling the non-occupied areas through electropolyermization ofan aryl diazonium salt (ADS). Nanocavities bearing the shape of theAu nanoparticles were formed upon the electrochemical dissolutionof the nanoparticles, which were used for the reuptake of the Au nanoparticlesstabilized by the different isomers. High reuptake selectivity wasfound where the originally imprinted nanoparticles were recognizedbetter than the Au nanoparticles stabilized by other MBA isomers.Furthermore, an imprinted matrix by nanoparticles stabilized by 4-MBAcould also recognize nanoparticles stabilized by 2-MBA, and vice versa.A detailed study using Raman spectroscopy and electrochemistry disclosedthe organization of the capping isomers on the nanoparticles as wellas the specific nanoparticle-matrix interactions that were responsiblefor the high reuptake selectivity observed. Specifically, the Ramanband at ca. 910 cm(-1) for all AuNP-matrixsystems implies the formation of a carboxylic acid dimer and thusthe interaction of the ligands with the matrix. These results haveimplications for the selective and simple sensing of engineered nanoparticles.

Automated summary

Researchers have developed a promising method for selectively detecting amino acid gold nanoparticles. By adsorption, filling, and electrochemical dissolution, they were able to create nanocavities with the shape of the nanoparticles. Spectroscopic and electrochemical studies revealed the interactions between the nanoparticles and the matrix. These findings have implications for the selective and simple sensing of nanoparticles.