Biohybrid structures formed by noncovalent interaction between avidin as a bridging unit and biotinylated glycodendrimers based on poly(propyleneimine) (GD-B) have potential for biomedical application. Therefore, an exact knowledge about molar mass, dispersity, size, shape, and molecular structure is required. Asymmetrical flow field-flow fractionation (AF4) was applied to separate pure and assembled macromolecules according to their diffusion coefficients. The complex biohybrid structures consist of single components (avidin, differently valent GD-B) and nanostructures. These nanostructures were systematically studied depending on the degree of biotinylation and ligand−receptor stoichiometry by AF4 in combination with dynamic and static light scattering detection. This enables the quantification of composition and calculation of molar masses and radii, which were used to analyze scaling properties and apparent density of the formed structures. These data are compared to hydrodynamic radii obtained by applying the retention theory to the AF4 data. It is shown that depending on their architecture the molecular shape of biohybrid structures is changed from rod-like to spherical toward network-like behavior.

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We report the fabrication and characterization of highly dense field-effect-transistor (FET) arrays based on single-walled carbon nanotubes (SWCNTs). The nanotubes were sorted according to the electronic type by using density gradient ultracentrifugation (DGU). By employing dielectrophoresis (DEP), SWCNTs with enriched semiconducting (sc) content were systematically integrated as active elements into FETs. The performance of air-operating FETs was addressed via an extended statistic study involving both electrical and structural analyses. The competitive impact of nanotube purity and assembly as well as the metal electrode composition and a thermal treatment on the final device performance was shown. Regardless of the used sc-content, the device-to-device consistency was improved via employing annealing up to 250 °C for 1 h in a vacuum. The observed clockwise hysteresis, known so far only in connection with CNT–FETs built on ferroelectric substrates as well as electrolyte gated CNT–FETs, was found to reverse upon annealing. Moreover, a simple approach in producing air-stable ambipolar transistors is pointed out only via change of the adhesion layer for the Pd electrodes. The annealing study, repeated on such systems, supports the previous results and provides complementary information via a reliable monitoring of the off-state. Indications for a doping-like effect, which partially compromises the device performance in terms of threshold voltage shifts and increased off-state currents, are revealed and discussed.

Due to their intrinsic properties, single‐walled carbon nanotubes (SWCNTs) are promising candidates for source‐drain channels in field‐effect transistors (FETs). However, their application in transistors requires semiconducting tubes, and thus, sorting of SWCNTs according to those. The basis for an efficient sorting is the dispersion of the material that usually includes but is not limited to applying tip sonication in the presence of appropriate amphiphilic molecules. We present a high semiconducting enrichment of surfactant‐wrapped arc discharge SWCNTs via sorting according to electronic type by applying density gradient ultracentrifugation (DGU). We utilized a common combination of anionic surfactants, but optimized the sonication time during the dispersion step of the SWCNTs and the duration of performing DGU. Furthermore, we used UV–Vis spectroscopy to determine the differences in the content of metallic (m) and semiconducting (sc) SWCNTs of different samples. By the refinement of the conditions, we have achieved an enrichment of sc‐SWCNTs up to 98% in two sorting steps.