Selective Recognition by Nanoparticle Imprinted Thin Films
Final Report Abstract
This project dealt with nanoparticle imprinted matrices (NAIMs) for the selective recognition of nanoparticles. NAIM systems are obtained by binding template nanoparticles to a surface, e.g., an electrode, followed by formation of an organic film with a controlled thickness that approximately equals the radius of the nanoparticles. After removal of the template nanoparticles, the film contains cavities that are able to re-uptake analyte nanoparticles with the same size and a chemically similar ligand shell as was used for the templating process. Such materials could in principle be used as recognition elements in sensors for nanoparticles or as coatings for materials by which nanoparticles can be separated in a chromatographic process. Within this realm, the project aimed for new ways of tuning the selectivity of the NAIM system. The selectivity depends on the size of the nanoparticles and on the molecular interaction of the molecular groups within the NAIM cavity and the ligand shell of the nanoparticles. This is a very important property, because the toxicity of nanoparticles does not only depend on the elemental composition of the nanoparticle, but also on the chemical nature of the ligand shell of the nanoparticle that determines how the nanoparticles can cross cell membranes and other interfaces within biological organisms. We followed an approach in which the core material of the template and analyte nanoparticles are different, to allow different techniques for the removal of the template nanoparticles and the detection of the analyte nanoparticles. Especially electrochemical dissolution of the analyte nanoparticles was selected for detection of the analyte nanoparticles because this technique allows to distinguish between nanoparticles residing within cavities and those that are retained outside of the cavity. We could show that NAIM systems constructed from polyplumbagin and imprinted with amine terminatedSiO2 nanoparticles can be further modified by conjugate addition of substituted organic thiols. In this way, a NAIM system can be tuned for the uptake of gold nanoparticles with different ligand shells. The actual uptake process also depends greatly on other solution conditions such as pH because this determines the protonation state of functional groups and thus electrostatic interaction between the matrix and the nanoparticles. Other combinations of matrix system, template and analyte nanoparticles were explored but did not work as well. Common problems were long times required for the uptake of the analyte nanoparticles or changes of the film morphology during removal of template nanoparticles.
Publications
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Covalent Modification of Nanoparticle‐Imprinted Matrices for Selective Nanoparticle Recognition. ChemElectroChem, 10(14).
Samuel, Sweety Ann & Wittstock, Gunther
