Comparison of the survival rates of spiral ganglion neurons after 48 h hof cultivation.

<p>Cells were cultivated in the presence of amino-modified nanoparticles (NPSNP-NH₂; light grey), BDNF-loaded amino-modified nanoparticles (dark grey) and amino-modified nanoparticles with an exogenous addition of 50 ng mL^-1 BDNF (light grey, striped). Values are given as mean ± standard error of the mean (<i>N</i> = 2, <i>n</i> = 3). Statistical assessment was performed using one-way ANOVA with Bonferroni´s multiple comparison test (n.s. = not significant, *p<0.05; **p<0.01; ***p<0.001). Asterisks over the bars indicate the significance of the survival rates of different conditions compared to the negative control (serum-free SGC medium). Asterisks between two bars indicate the significance between the respective conditions.</p

Neurite length of SGNs cultivated with BDNF-loaded (dark grey) and BDNF-free NPSNPs with (light grey, striped) or without (light grey) an additional exogenous BDNF supply.

<p>Values are given as mean ± standard error of the mean (<i>N</i> = 2, <i>n</i> = 3). Statistical assessment was performed using one-way ANOVA with Bonferroni´s multiple comparison test (n.s. = not significant, *p<0.05; **p<0.01; ***p<0.001). Asterisks over the bars indicate the significance of the survival rates of the different conditions compared to the medium control (serum-free SGC medium).</p

Azobenzene Guest Molecules as Light-Switchable CO₂ Valves in an Ultrathin UiO-67 Membrane

Metal–organic frameworks (MOFs) with an exceptionally large pore volume and inner surface area are perfect materials for loading with intelligent guest molecules. First, an ultrathin 200 nm high-flux UiO-67 layer deposited on a porous α-Al₂O₃ support by solvothermal growth has been developed. This neat UiO-67 membrane is then used as a host material for light-responsive guest molecules. Azobenzene (AZB) is loaded in the pores of the UiO-67 membrane. From adsorption measurements, we determined that the pores of UiO-67 are completely filled with AZB and, thereby, steric hindrance inhibits any optical switching. After <i>in situ</i> thermally controlled desorption of AZB from the membrane, AZB can be switched and gas permeation changes are observed, yielding an uncomplicated and effective smart material with remote controllable gas permeation. The switching of AZB in solution and inside the host could be demonstrated by ultraviolet–visible spectroscopy. Tracking the completely reversible control over the permeance of CO₂ and the H₂/CO₂ separation through the AZB-loaded UiO-67 layer is possible by <i>in situ</i> irradiation and permeation. Mechanistic investigations show that a light-induced gate opening and closing takes place. A remote controllable host–guest, ultrathin smart MOF membrane is developed, characterized, and applied to switch the gas composition by external stimuli

Quantification of the amount of immobilized BDNF on unmodified and amino-modified NPSNPs which were incubated in a solution containing 1 μg mL^-1 BDNF.

<p>Quantification of the amount of immobilized BDNF on unmodified and amino-modified NPSNPs which were incubated in a solution containing 1 μg mL^-1 BDNF.</p

Microscopic images of spiral ganglion cells (SGCs) after two days of cultivation in different media composition.

<p>The cells were cultivated in presence of the supernatants from the release experiments of BDNF-loaded amino-modified NPSNPs (NPSNP-NH₂-BDNF) or of BDNF-free amino-modified NPSNPs (NPSNP-NH₂). For comparison, SGCs were also cultivated in serum-free SGC medium (medium) and in serum-free medium supplemented with BDNF (50 ng mL^-1 BDNF) as well as in a 1:1 serum-free medium/PBS (0.1% BSA) solution.</p

Relative cell viabilities of NIH3T3 fibroblasts in the presence of unmodified and amino-modified nanoparticles in different concentrations determined by the NRU assay after an incubation for four days.

<p>Values are given as mean ± standard error of the mean (<i>n</i> = 3).</p

BDNF release profile of unmodified NPSNPs in PBS (0.1% BSA) over 60 days at 37°C.

<p>The left axis represents the cumulative BDNF release with regard to 1 mg of nanoparticles and the right axis shows the cumulative release of BDNF referred to 1 mL release medium.</p

Representative microscopic images of spiral ganglion cell cultures cultivated for 48 h.

<p>The cells were cultivated in the presence of amino-modified nanoparticles (w/o BDNF), BDNF-loaded amino-modified nanoparticles (immobilized BDNF) and amino-modified nanoparticles with an exogenous addition of 50 ng mL^-1 BDNF (exogenous BDNF) in two different concentrations. For comparison, SGCs were also cultivated in serum-free SGC medium (medium) and in serum-free medium supplemented with BDNF (50 ng mL^-1 BDNF) as well as in a serum-free medium/PBS solution (1:1) (PBS (0.1% BSA)).</p

Zeta potential titration curves for the unmodified NPSNPs in comparison to the amino-modified NPSNPs.

<p>Zeta potential titration curves for the unmodified NPSNPs in comparison to the amino-modified NPSNPs.</p

Scheme of the possible interactions between BDNF with (left) unmodified NPSNPs and (right) amino-modified NPSNPs.

<p>With unmodified NPSNPs, BDNF can interact via hydrogen bonds and electrostatic interactions, and with amino-modified NPSNPs via hydrogen bonding, electrostatic interactions and via hydrophobic effects. This schematic view does not show the nanoparticles, atoms and the protein with their real sizes.</p