Electrochemically Deposited Sol–Gel Based Nanoparticle-Imprinted Matrices for the Size-Selective Detection of Gold Nanoparticles

Abstract

Nanoparticles imprinted matrices (NAIMs) is a new approach, in which nanoparticles (NPs) are imprinted in a matrix followed by their removal to form highly selective voids that can recognize the original NPs. In this study, the effect of a sol–gel matrix on the imprinting and reuptake of gold nanoparticles (AuNPs) is examined. Specifically, indium tin oxide (ITO) films were modified with a positively charged polymer, on which the negatively charged AuNPs stabilized with citrate (AuNPs-cit) were adsorbed. This was followed by the electrochemical deposition of sol–gel matrices with different thicknesses and functional groups onto the ITO/AuNPs-cit. Electrochemical oxidation dissolved the AuNPs-cit and formed cavities in the sol–gel films, which fit both the size and shape of the AuNPs-cit. Reuptake of these NPs from an aqueous solution was successful using the imprinted films, whereas the non-imprinted films did not re-uptake the AuNPs-cit. Furthermore, the thickness of the sol–gel layers as well as the type of the silanes that were deposited play an important role on the recognition ability of the NAIM. Finally, we found that the NAIMs are selective, and larger AuNPs-cit were not recognized by the imprinted matrix.

Shell–Matrix Interaction in Nanoparticle-Imprinted Matrices: Implications for Selective Nanoparticle Detection and Separation

“…Furthermore, the matrix should grow controllably from the surface to the solution, which implies that electrografting is an ideal approach for the formation of an electrically insulating matrix . We have already suggested the use of sol–gel electrodeposition, phenol, or aryldiazonium salt (ADS) electrografting . The latter is in particular convenient due to three reasons.…”

“…The high selectivity achieved was primarily due to size exclusion. More recently, we have demonstrated that the nature of the matrix and its interaction with the imprinted NPs affect their recognition and play a major role. − NAIMs are envisioned to enable the assembly of either sensors or separation devices for NPs.…”

Size-Selective Detection of Nanoparticles in Solution and Air by Imprinting

“…Importantly, the sensing layer is prepared through the NAIM methodology in which NPs are initially placed on the IDE and a thin film is formed covering the nonoccupied areas between the NPs. Removing the embedded NPs leaves behind cavities, which can reuptake the targeted NPs. − …”

“…In this respect, the IUPAC recommendation of numerous techniques for NPs characterization should be mentioned, but these require heavy-duty instrumentation . “Nanoparticle-imprinted matrices (NAIM)” is an innovative approach developed in our laboratory for NP sensing. − NAIM resembles the well-known molecularly imprinted polymer (MIP) approach. − In NAIM, nanocavities with specific size, shape, and chemical composition are formed through imprinting of NPs in soft thin layers. ,, The cavities can then reuptake NPs according to their size and surface properties. Notably, previous studies of NAIM systems were limited to metallic NPs and demonstrated applications only in solutions.…”

From past research experiences looking to the future of sol–gel

“…In 2014, we started to work on this interesting deposition technique, attracted by the possibility to deposit protective layers on the inner surface of complex metallic substrates. Some papers have been produced [25][26][27][28][29], with very interesting results, but a lot of work is still needed to fully understand and develop this method. Among the scientific aspects awaiting clarification, the structure and density of the layers obtained under basic conditions are quite important, especially looking to applications.…”