Biokraftstoffe

BIOKRAFTSTOFFE Biokraftstoffe / Knebel, Alexander (Rights reserved) ( -

Untersuchungen zum Einfluss von Retinolderivaten auf die Differenzierung von kornealen Limbusepithelzellen im Kontext der kongenitalen Aniridie

Hintergrund und Ziele Die kongenitale PAX6-Aniridie führt in 20% der Fälle zur Aniridie-assoziierten Keratopathie (AAK) und geht mit Differenzierungsstörungen von Limbusepithelzellen (LEZ) bzw. einer Limbusstammzellinsuffizienz einher. In Vorarbeiten konnte gezeigt werden, dass in LEZ von AAK- Patienten und im Aniridie-Zellmodell die Genexpression der am Retinolstoffwechsel beteiligten Enzyme ADH7 und ALDH1A1 sowie die Genexpression der Differenzierungsmarker DSG1 und KRT3 reduziert ist. Ziel der Studie war es zu ermitteln, ob die Differenzierung der LEZ über die Behandlung mit Retinolderivaten gesteigert oder durch eine Herunterregulation von ADH7 mittels siRNA vermindert werden kann. Außerdem wurde untersucht, ob der ABC-Transporter ABCG2 am Retinoltransport aus der Zelle beteiligt sein könnte. Dazu wurden die Auswirkungen von Retinol in Anwesenheit eines ABCG2-Blockers analysiert. Methoden Aus gesunden Spenderhornhäuten wurden LEZ isoliert, kultiviert und mit Retinol und Retinsäure für jeweils 24 Stunden (0,5 μM, 1,5 μM) sowie 48 Stunden (1 μM, 5 μM) inkubiert. LEZ wurden zudem mit Retinol (100 nM) sowie einem ABCG2-Blocker (100 nM) für 48 Stunden inkubiert. Zusätzlich wurden die LEZ mit siRNA gegen ADH7 (5 nM) für 48 Stunden behandelt. Folgende Transkriptionslevel wurden mit qPCR analysiert: PAX6, ADH7, ALDH1A1, die Differenzierungsmarker KRT3, KRT12, KRT19 und DSG1, der potenzielle Stammzellmarker ABCG2, der Proteaseinhibitor SPINK7 und der Proliferationsmarker Ki67. Die statistische Auswertung erfolgte mittels one-way ANOVA und anschließendem Dunnett ́s- bzw. Tukey multiple comparisons test. Die Untersuchung der Proteinmengen von PAX6, ADH7 und KRT12 nach Behandlung mit Retinolderivaten für 48 Stunden erfolgte mittels Western Blot. Die densitometrische Analyse der Proteinbanden erfolgte mit ImageJ. Für die statistische Auswertung wurde ein one-way ANOVA mit anschließendem Dunnett ́s- bzw. Tukey multiple comparisons test durchgeführt. Ergebnisse Die Genexpression von PAX6 war unter Retinol-Behandlung erhöht (pmax=0,0025) und unter Retinsäure-Behandlung vermindert (pmax=0,0448). Die Genexpression von ABCG2 (p=0,0024), SPINK7 (pmax= 0,0198), DSG1 (pmax= 0,0023), Ki67 (pmax= 0,0354) und KRT3 (pmax= 0,0103) war nach Behandlung mit Retinolderivaten signifikant reduziert. Die Marker KRT12 (pmax= 0,0341) und KRT19 (p= 0,0394) waren signifikant erhöht, die Marker ADH7 und ALDH1A1 waren unverändert. Die Proteinexpression von PAX6 war durch die Behandlung mit Retinolderivaten nicht signifikant verändert (p≥ 0,16). Die Proteinexpression des Markers ADH7 war unter der Behandlung mit Retinsäure signifikant reduziert (p= 0,028 für 5 μM) und mit Retinol-Behandlung signifikant erhöht (p= 0,049 für 1 μM; p= 0,048 für 5 μM). Die Proteinexpression von KRT12 war durch die Behandlung mit Retinsäure signifikant hochreguliert (p= 0,038 für 5 μM). Die Behandlung mit dem ABCG2-Blocker zeigte keine signifikanten Veränderungen der untersuchten Marker. Im siRNA-Modell gegen ADH7 ließ sich eine stark herunterregulierte mRNA von ADH7 feststellen, die anderen Marker waren nicht signifikant verändert. Schlussfolgerungen Die Differenzierung von LEZ wird durch die Behandlung mit Retinolderivaten nicht gefördert. Die mittels siRNA induzierte Herunterregulation von ADH7 hat keinen Effekt auf die Differenzierung der LEZ. Der ABC-Transporter ABCG2 hat keinen Einfluss auf den Auswärtstransport von Retinol aus LEZ. Es gibt Hinweise auf ein mögliches Überangebot von Retinolderivaten in LEZ bei kongenitaler Aniridie.Background and purpose PAX6-aniridia leads to aniridia-associated keratopathy (AAK) in 20% of cases and is associated with differentiation disorder of limbal epithelial cells (LEC) or limbal stem cell insufficiency. In LEC of AAK patients and in the aniridia cell model, gene expression of the enzymes ADH7 and ALDH1A1 (involved in retinol metabolism) is reduced together with expression of the differentiation markers DSG1 and KRT3. The purpose of the study was to determine whether the differentiation of LEC is increased by treatment with retinol derivatives or decreased by downregulation of ADH7 via siRNA. We also aimed to investigate whether the ABC transporter ABCG2 may be involved in retinol transport from the cell. For this purpose, the impact of the retinol effect in presence of an ABCG2 blocker was analyzed. Methodology LEC were isolated from healthy donor corneas, cultured and incubated with retinol and retinoic acid for 24 hours (0.5 μM, 1.5 μM) and 48 hours (1 μM, 5 μM), respectively. LEC were also incubated with retinol (100 nM) as well as an ABCG2 blocker (100 nM) for 48 hours. In addition, LEC were treated with siRNA against ADH7 (5 nM) for 48 hours. The following transcription levels were analyzed with qPCR: PAX6, ADH7, ALDH1A1, the differentiation markers KRT3, KRT12, KRT19, and DSG1, the potential stem cell marker ABCG2, the protease inhibitor SPINK7 and the proliferation marker Ki67. Statistical evaluation was performed by one-way ANOVA followed by Dunnett's or Tukey multiple comparisons test. The analysis of the protein amount of PAX6, ADH7, and KRT12 after treatment with retinol derivatives for 48 hours was performed by Western blot. The densitometric analysis of the protein bands was performed with ImageJ and the statistical evaluation by one-way ANOVA and the subsequent Dunnett's or Tukey multiple comparisons test. Results PAX6 mRNA expression was increased after treatment with retinol (pmax= 0.0025) and decreased after treatment with retinoic acid (pmax= 0.0448). ABCG2 (p= 0.0024), SPINK7 (pmax= 0.0198), DSG1 (pmax= 0.0023), Ki67 (pmax= 0.0354) and KRT3 mRNA expression (pmax= 0.0103) was significantly decreased after treatment with retinol derivatives. mRNA expression of the markers KRT12 (pmax= 0.0341) and KRT19 was significantly increased (p= 0.0394), whereas ADH7 and ALDH1A1 mRNA expression remained unchanged. PAX6 protein expression remained unchanged following by treatment with retinol derivatives (p≥ 0.16). ADH7 protein expression was significantly reduced after retinoic acid treatment (p= 0.028 for 5 μM) and increased significantly following retinol treatment (p= 0.049 for 1 μM; p= 0.048 for 5 μM). KRT12 protein expression was significantly upregulated through retinoic acid treatment (p= 0.038 for 5 μM). Treatment with the ABCG2 blocker showed no significant effect on expression of the investigated markers. In the siRNA model against ADH7, a strongly downregulated ADH7 mRNA expression could be verified, however, expression of the other analyzed markers did not change significantly. Conclusions LEC differentiation is not stimulated by retinol derivate treatment. The siRNA induced downregulation of ADH7 does not influence LEC differentiation. ADH7 downregulation using siRNA has no effect on LEC differentiation. The ABC transporter ABCG2 has no influence on the outward transport of retinol from LEC. There is evidence for a possible oversupply of retinol derivatives in LEC, in congenital aniridia

Die Energiewende auf die Straße bringen

DIE ENERGIEWENDE AUF DIE STRASSE BRINGEN Die Energiewende auf die Straße bringen / Knebel, Alexander (Rights reserved) ( -

Pore-in-Pore Engineering in a Covalent Organic Framework Membrane for Gas Separation

Covalent organic framework (COF) membranes have emerged as a promising candidate for energy-efficient separations, but the angstrom-precision control of the channel size in the subnanometer region remains a challenge that has so far restricted their potential for gas separation. Herein, we report an ultramicropore-in-nanopore concept of engineering matreshka-like pore-channels inside a COF membrane. In this concept, α-cyclodextrin (α-CD) is in situ encapsulated during the interfacial polymerization which presumably results in a linear assembly (LA) of α-CDs in the 1D nanochannels of COF. The LA-α-CD-in-TpPa-1 membrane shows a high H2 permeance (∼3000 GPU) together with an enhanced selectivity (>30) of H2 over CO2 and CH4 due to the formation of fast and selective H2-transport pathways. The overall performance for H2/CO2 and H2/CH4 separation transcends the Robeson upper bounds and ranks among the most powerful H2-selective membranes. The versatility of this strategy is demonstrated by synthesizing different types of LA-α-CD-in-COF membranes

Current Trends in Metal–Organic and Covalent Organic Framework Membrane Materials

Metal–organic frameworks (MOFs) and covalent organic frameworks (COFs) have been thoroughly investigated with regards to applications in gas separation membranes in the past years. More recently, new preparation methods for MOFs and COFs as particles and thin‐film membranes, as well as for mixed‐matrix membranes (MMMs) have been developed. We will highlight novel processes and highly functional materials: Zeolitic imidazolate frameworks (ZIFs) can be transformed into glasses and we will give an insight into their use for membranes. In addition, liquids with permanent porosity offer solution processability for the manufacture of extremely potent MMMs. Also, MOF materials influenced by external stimuli give new directions for the enhancement of performance by in situ techniques. Presently, COFs with their large pores are useful in quantum sieving applications, and by exploiting the stacking behavior also molecular sieving COF membranes are possible. Similarly, porous polymers can be constructed using MOF templates, which then find use in gas separation membranes

Tunable molecular separation by nanoporous membranes

Metal-organic frameworks offer tremendous potential for efficient separation of molecular mixtures. Different pore sizes and suitable functionalizations of the framework allow for an adjustment of the static selectivity. Here we report membranes which offer dynamic control of the selectivity by remote signals, thus enabling a continuous adjustment of the permeate flux. This is realized by assembling linkers containing photoresponsive azobenzene-side-groups into monolithic, crystalline membranes of metal-organic frameworks. The azobenzene moieties can be switched from the trans to the cis configuration and vice versa by irradiation with ultraviolet or visible light, resulting in a substantial modification of the membrane permeability and separation factor. The precise control of the cis:trans azobenzene ratio, for example, by controlled irradiation times or by simultaneous irradiation with ultraviolet and visible light, enables the continuous tuning of the separation. For hydrogen:carbon-dioxide, the separation factor of this smart membrane can be steplessly adjusted between 3 and 8

Rapid photocatalytic degradation of phenol from water using composite nanofibers under UV

Background The removal of phenol from aqueous solution via photocatalytic degradation has been recognized as an environmentally friendly technique for generating clean water. The composite nanofibers containing PAN polymer, CNT, and TiO$_{2}$ NPs were successfully prepared via electrospinning method. The prepared photocatalyst is characterized by SEM, XRD, and Raman spectroscopy. Different parameters are studied such as catalyst amount, the effect of pH, phenol concentration, photodegradation mechanism, flow rate, and stability of the composite nanofiber to evaluate the highest efficiency of the photocatalyst. Results The composite nanofibers showed the highest photodegradation performance for the removal of phenol using UV light within 7 min. The pH has a major effect on the photodegradation of phenol with its maximum performance being at pH 5. Conclusions Given the stability and flexibility of the composite nanofibers, their use in a dynamic filtration is possible and can be even reused after several cycles

Metal-Organic Framework MIL-68(In)-NH2_{2} on the Membrane Test Bench for Dye Removal and Carbon Capture

The metal-organic framework (MOF) MIL-68(In)-NH$_{2}$ was tested for dye removal from wastewater and carbon capture gas separation. MIL-68(In)-NH$_{2}$ was synthesized as a neat, supported MOF thin film membrane and as spherical particles using pyridine as a modulator to shape the morphology. The neat MIL-68(In)-NH$_{2}$ membranes were employed for dye removal in cross-flow geometry, demonstrating strong molecular sieving. MIL-68(In)-NH$_{2}$ particles were used for electrospinning of poylethersulfone mixed-matrix membranes, applied in dead-end filtration with unprecedented adsorption values. Additionally, the neat MOF membranes were used for H$_{2}$/CO$_{2}$ and CO$_{2}$/CH$_{4}$ separation