Nanostructures with long-term stability at the surface of gold electrodes are generated by reconstituting the porin MspA from Mycobacterium smegmatis into a specially designed monolayer of long-chain lipid surfactant on gold. Tailored surface coverage of gold electrodes with long-chain surfactants is achieved by electrochemically assisted deposition of organic thiosulfates (Bunte salts). The subsequent reconstitution of the octameric-pore MspA is guided by its extraordinary self-assembling properties. Importantly, electrochemical reduction of copper(II) yields copper nanoparticles within the MspA nanopores. Electrochemical impedance spectroscopy, reflection electron microscopy, and atomic force microscopy (AFM) show that: 1) the MspA pores within the self-assembled monolayer (SAM) are monodisperse and electrochemically active, 2) MspA reconstitutes in SAMs and with a 10-nm thickness, 3) AFM is a suitable method to detect pores within SAMs, and 4) the electrochemical reduction of Cu2+ to Cu0 under overpotential conditions starts within the MspA pores.
We have reconstituted the channel porin MspA from M. smegmatis on a gold electrode into a long-chain lipid monolayer resembling a biological membrane. The tailored deposition of the self-assembled monolayer (SAM) on gold was achieved by employing electrochemically initiated generation of thiyl-radicals from organic thiosulfates (Bunte-Salts), which then adsorb onto the golds surface. At surface coverage of the lipids of approximately 80%, MspA reconstituted efficiently from the aqueous buffer into the SAM. The combination of cyclic voltammetry (CV), electrochemical impedance spectroscopy (EIS), reflection electron microscopy (REM) and the formation of copper(0)-nanoparticles from copper(II)-ions inside the MspA-channels proved that MspA forms SAM-spanning ion channels on gold, keeping the electrode (surface) accessible through the pores.
The synthesis of organic thiosulfates, up to 10 nm in length, which were tailored for generating artificial monomembranes on gold surfaces by electrochemically initiated deposition, was accomplished. (E)-3-(4-Hydroxyphenyl)acrylic acid (4-hydroxy cinnamic acid) was employed as aromatic head group and (C 10 H 20 -O-) n (n = 1, 3, 5, 7) building blocks were attached. The synthetic procedure comprises a series of nucleophilic substitutions under carefully defined conditions. Extended purification is crucial for eliminating non-reacted starting materials.
Das erste Reallabor des Bundeswirtschaftsministeriums fokussiert auf Wasserstofftechniken. Die Raffinerie Heide in Hemmingstedt baut dafür eine 30‐Megawatt‐Elektrolyseanlage.
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