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

Abstract

Nanoparticle-imprinted matrices (NAIMs) are an innovative approach for the efficient and selective recognition of nanoparticles (NPs). The NAIM system comprises the preparation of thin films in which NPs are embedded as a template. The removal of the template forms nanometric voids, which are subsequently used for the selective reuptake of NPs identical to those imprinted. The recognition ability depends on several parameters such as the geometrical compatibility between the voids and imprinted NPs, the thickness of the matrix, and the supramolecular interactions between the matrix and the NP capping agents. Herein, we studied carefully the NP−matrix interactions in three NAIM systems, which were prepared by imprinting identical-sized AuNPs, bearing different carboxylic acidfunctionalized thiols as capping agents, in a carboxylic acid-functionalized matrix. This experimental setup has enabled us to meticulously examine the selectivity of the NAIM systems driven by matrix−shell interactions. The three studied NAIM systems have shown high and selective reuptake ability once exposed to solutions of NPs stabilized with the same capping agent used for the imprinting process. In particular, the reuptake percentage of the originally imprinted AuNPs ranges from 50 to 80%, whereas the reuptake of AuNPs bearing different carboxylic capping agents than those imprinted was substantially lower (1−11%). Surfacesensitive polarization-modulation infrared reflection-absorption spectroscopy was utilized to correlate the selectivity of the NAIM systems and hydrogen bonding detected between the capping agents and the matrix. This study paves the way for the rational design of NAIM systems, which can be tuned according to the desired shell−matrix interactions and eventually applied in sensing and separation technologies.

Technical Challenges of Molecular-Imprinting-Based Optical Sensors for Environmental Pollutants

“…However, analyzing the elution solution does not always work because the template may degrade or decompose in the elution solvent. As an illustration, to leach quantum dots (QDs) and gold nanoparticle templates from MIPs, skeleton hydrofluoric acid (HF) 7 and electrochemical oxidation 8 are used, respectively. Under these conditions, complete template removal is indirectly determined by the vanishing fluorescence emission of the MIP matrix in the former method and the disappearing oxidation peak in the latter method.…”

Electrochemical Detection of Silica Nanoparticles by Nanoparticle Imprinted Matrices

“…Nanoparticle‐imprinted matrix (NAIM) is a pioneering approach that tackles the detection and monitoring of NPs [25–34] . The NAIM approach is based on the well‐known concept of molecularly imprinted polymers (MIPs) [35–38] .…”

“…In this fashion, nano‐sized voids with complementary shapes, sizes, and chemical functionalities are formed on a thin layer and serve as binding locations to capture NPs. Previous works have demonstrated the ability of NAIM systems to detect NPs by these voids in addition to their selectivity toward NPs size [26–29] (core or shell size), composition [29,32] (Au or Ag), and chemical functionality [25,33] . The electrochemical signal in these NAIM systems was generated by the direct electrochemical dissolution of metallic NPs questioning whether these systems can detect non‐conductive NPs, which cannot be electrochemically dissolved [25–27,29,30] …”

“…Nanoparticle-imprinted matrix (NAIM) is a pioneering approach that tackles the detection and monitoring of NPs. [25][26][27][28][29][30][31][32][33][34] The NAIM approach is based on the well-known concept of molecularly imprinted polymers (MIPs). [35][36][37][38] However, the imprinting process is performed on NPs by a thin layer instead of molecules.…”

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

“…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.…”