Electrochemical Detection of Silica Nanoparticles by Nanoparticle Imprinted Matrices

Abstract

Nanoparticle (NP) toxicity is a severe environmental threat that calls for the development of novel field-effective platforms for NP detection and speciation according to their physicochemical properties. In this regard, nanoparticle-imprinted matrix (NAIM) is an innovative approach that enables the selective detection of NPs by their size, shape, surface chemistry, and composition. However, thus far, NAIM systems have mainly been used for detecting metallic NPs such as Au or Ag by electrochemical dissolution. Herein, we show that a facile electrochemical detection of non-conductive silica-NPs can be achieved by the NAIM approach. Specifically, the physical blocking of nanocavities was indirectly monitored by recording the redox activity of hexacyanoferrate(III) inside the nanocavities following exposure to silica-NPs using cyclic voltammetry (CV) and square wave voltammetry (SWV). This approach was examined for two different matrices based on phenol and 3-aminophenol monomers. Notably, we observed a dissimilar redox activity of hexacyanoferrate(III) upon reuptake, pointing to the importance of molecular interactions in NPs recognition. In addition, highspatial-resolution vibrational mapping was conducted by IR scattering-type scanning near-field optical microscopy (IR-sSNOM) imaging to characterize the physical entrapment of silica-NPs by the matrix in the nanoscale.

High Recognition of Isomer-Stabilized Gold Nanoparticles through Matrix Imprinting

“…The evidence of the deposition of a blocking layer made of the electrografted ADS-COOH can be seen in Figure S9, where the CV of hexacyanoferrate­(III) was studied as a function of the number of the electrografted CV cycles. It is evident that the CV current decreases with the increasing number of electrografted scans, which corresponds to the increasing film thickness . Specifically, three scans of ADS-COOH block electron transfer at an ITO/PEI/ADS-COOH surface without NPs, whereas the adsorption of the NPs clearly allows electron transfer.…”

“…In this emerging field termed surface-imprinted polymers (SIPs), a thin matrix imprints only part of the entity to enable its easy removal and rebinding. In the SIP approach, imprinting is achieved by the formation of a thin layer, thinner than the template dimension, on a solid support …”

Imprinting of nanoparticles in thin films: Quo Vadis?

“…The preference for 20 nm AgNP over 50 nm AuNP greatly exceeded the expected difference in the diffusion of the two size-NPs. More recently, Dery et al 160 exhibited a NAIM approach for the electrochemical detection of non-conductive silica-NPs ( Fig. 15 ).…”