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    Ageing of alkylthiol-stabilized gold nanoparticles
    (Hoboken, NJ : Wiley, 2015) Lacava, Johann; Weber, Anika; Kraus, Tobias
    The ageing of spherical gold nanoparticles having 6-nm-diameter cores and a ligand shell of dodecanethiol is investigated under different storage conditions. Losses caused by agglomeration and changes in optical particle properties are quantified. Changes in colloidal stability are probed by analytical centrifugation in a polar solvent mixture. Chemical changes are detected by elementary analysis of particles and solvent. Fractionation occurs under all storage conditions. Ageing is not uniform but broadens the property distributions of the particles. Small-number statistics in the ligand shell density and the morphological heterogeneity of particles are possible explanations. Washing steps exacerbate ageing, a process that could not be fully reversed by excess ligands. Dry storage is not preferable to storage in solvent. Storage under inert argon atmosphere reduces losses more than all other conditions but could not prevent it entirely.
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    Maximizing transfection efficiency of vertically aligned silicon nanowire arrays
    (Hoboken, NJ : Wiley, 2015) Elnathan, Roey; Delalat, Bahman; Brodoceanu, Daniel; Alhoud, Hashim; Harding, Frances J.; Buehler, Katrin; Nelson, Adrienne; Isa, Lucio; Kraus, Tobias; Voelcker, Nicolas H.
    Vertically aligned silicon nanowire (VA‐SiNW) arrays are emerging as a powerful new tool for gene delivery by means of mechanical transfection. In order to utilize this tool efficiently, uncertainties around the required design parameters need to be removed. Here, a combination of nanosphere lithography and templated metal‐assisted wet chemical etching is used to fabricate VA‐SiNW arrays with a range of diameters, heights, and densities. This fabrication strategy allows identification of critical parameters of surface topography and consequently the design of SiNW arrays that deliver plasmid with high transfection efficiency into a diverse range of human cells whilst maintaining high cell viability. These results illuminate the cell‐materials interactions that mediate VA‐SiNW transfection and have the potential to transform gene therapy and underpin future treatment modalities.