The selective recognition of nanoparticles (NPs) can be achieved by nanoparticle-imprinted matrices (NAIMs), where NPs are imprinted in a matrix followed by their removal to form voids that can reuptake the original NPs. The recognition depends on supramolecular interactions between the matrix and the shell of the NPs, as well as on the geometrical suitability of the imprinted voids to accommodate the NPs. Here, gold NPs stabilized with citrate (AuNPs-cit) were preadsorbed onto a conductive surface followed by electrografting of p-aryldiazonium salts (ADS) with different functional groups. The thickness of the matrix was carefully controlled by altering the scan number. The AuNPs-cit were removed by electrochemical dissolution. The recognition of the NAIMs was determined by the reuptake of the original AuNPs-cit by the imprinted voids. We found that the recognition efficiency is a function of the thickness of the NAIM layer and is sensitive to the chemical structure of the matrix. Specifically, a subtle change of the functional group of the p-aryldiazonium building block, which was varied from an ether to an ester, significantly affected the recognition of the NPs.

We report the first attempt of using molecularly imprinted polymers (MIPs) in the shape of nanoparticles that were doped with gold nanoparticles (AuNPs) for surface enhanced Raman scattering (SERS)-based sensing of molecular species. Specifically, AuNPs doped molecularly imprinted nano-spheres (AuNPs@nanoMIPs) were synthesized by one-pot precipitation polymerization using Sudan IV as the template for the SERS sensing. The AuNPs@nanoMIPs were characterized by various modes of scanning transmission electron microscopy (STEM) that showed the exact location of the AuNPs inside the MIP particles. The effects of Au concentration and solution stirring on the shape and the polydispersity of the particles were studied. Significant enhancement of the Raman signals was observed only when the MIP particles were doped with the AuNPs. The SERS signal improved significantly with increase in the Au concentration inside the AuNPs@nanoMIPs. Selectivity measurements of the Sudan IV imprinted AuNPs@nanoMIPs carried out with different Sudan derivatives showed high selectivity of the AuNPs-doped MIP particles.