Tailoring the Weight of Surface and Intralayer Edge States to Control LUMO Energies.

The energies of the frontier molecular orbitals determine the optoelectronic properties in organic films, which are crucial for their application, and strongly depend on the morphology and supramolecular structure. The impact of the latter two properties on the electronic energy levels relies primarily on nearest-neighbor interactions, which are difficult to study due to their nanoscale nature and heterogeneity. Here, an automated method is presented for fabricating thin films with a tailored ratio of surface to bulk sites and a controlled extension of domain edges, both of which are used to control nearest-neighbor interactions. This method uses a Langmuir-Schaefer-type rolling transfer of Langmuir layers (rtLL) to minimize flow during the deposition of rigid Langmuir layers composed of π-conjugated molecules. Using UV-vis absorption spectroscopy, atomic force microscopy, and transmission electron microscopy, it is shown that the rtLL method advances the deposition of multi-Langmuir layers and enables the production of films with defined morphology. The variation in nearest-neighbor interactions is thus achieved and the resulting systematically tuned lowest unoccupied molecular orbital (LUMO) energies (determined via square-wave voltammetry) enable the establishment of a model that functionally relates the LUMO energies to a morphological descriptor, allowing for the prediction of the range of accessible LUMO energies.

Four-Level Structural Hierarchy: Microfluidically Supported Synthesis of Polymer Particle Architectures Incorporating Fluorescence-Labeled Components and Metal Nanoparticles.

Hierarchical assemblies of functional polymer particles are promising due to their surface as well as physicochemical properties. However, hierarchical composites are complex and challenging to form due to the many steps necessary for integrating different components into one system. Highly structured four-level composite particles were formed in a four-step process. First of all, gold (Au) nanoparticles, poly(methyl methacrylate) (PMMA) nanoparticles, and poly(tripropylene glycol diacrylate) (poly-TPGDA) microparticles were individually synthesized. By applying microfluidic techniques, polymer nano- and microparticles were formed with tunable size and surface properties. Afterwards, the negatively charged gold nanoparticles and PMMA particles functionalized with a positively charged surface were mixed to form Au/PMMA assemblies. The Au/PMMA composites were mixed and incubated with poly-TPGDA microparticles to form ternary Au/PMMA/poly-TPGDA assemblies. For the formation of composite-containing microparticles, Au/PMMA/poly-TPGDA composites were dispersed in an aqueous acrylamide-methylenebisacrylamide solution. Monomer droplets were formed in a co-flow microfluidic device and photopolymerized by UV light. In this way, hierarchically structured four-level composites consisting of four different size ranges─0.025/0.8/30/1000 µm─were obtained. By functionalizing polymer nano- and microparticles with different fluorescent dyes, it was possible to visualize the same composite particle under two different excitation modes (λex = 395-440 and λex = 510-560 nm). The Au/PMMA/poly-TPGDA composite-embedded polyacrylamide microparticles can be potentially used as a model for the creation of composite particles for sensing, catalysis, multilabeling, and biomedical applications.

Water-Soluble Pristine C60 Fullerene Inhibits Liver Alterations Associated with Hepatocellular Carcinoma in Rat.

Excessive production of reactive oxygen species is the main cause of hepatocellular carcinoma (HCC) initiation and progression. Water-soluble pristine C60 fullerene is a powerful and non-toxic antioxidant, therefore, its effect under rat HCC model and its possible mechanisms were aimed to be discovered. Studies on HepG2 cells (human HCC) demonstrated C60 fullerene ability to inhibit cell growth (IC50 = 108.2 µmol), to induce apoptosis, to downregulate glucose-6-phosphate dehydrogenase, to upregulate vimentin and p53 expression and to alter HepG2 redox state. If applied to animals experienced HCC in dose of 0.25 mg/kg per day starting at liver cirrhosis stage, C60 fullerene improved post-treatment survival similar to reference 5-fluorouracil (31 and 30 compared to 17 weeks) and inhibited metastasis unlike the latter. Furthermore, C60 fullerene substantially attenuated liver injury and fibrosis, decreased liver enzymes, and normalized bilirubin and redox markers (elevated by 1.7-7.7 times under HCC). Thus, C60 fullerene ability to inhibit HepG2 cell growth and HCC development and metastasis and to improve animal survival was concluded. C60 fullerene cytostatic action might be realized through apoptosis induction and glucose-6-phosphate dehydrogenase downregulation in addition to its antioxidant activity.

Identification and evaluation of cell- growth-inhibiting bDtBPP-analogue degradation products from phosphite antioxidants used in polyolefin bioprocessing materials.

The inhibiting effect of the secondary phosphite antioxidant degradation product bis(2,4-di-tert-butylphenyl)phosphate (bDtBPP) on cell growth is well-known. The present study describes structurally related compounds which are likely to be formed from similar widely used phosphite antioxidants used in materials for the manufacturing of single-use (SU) equipment. Two potential candidates of such compounds-3,3',5,5'-tetra-tert-butyl-2,2'-dihydroxybiphenylphosphate (TtBBP) and bis(p-nonylphenyl)phosphate (bNPP)-were identified by chromatography and mass spectrometry followed by synthesis and X-ray structure elucidation. Additionally, the formation of TtBBP was confirmed in an analytical degradation study and its migration from SU bioprocessing material was estimated. The cytotoxicity evaluation by means of cell culture spiking experiments and flow cytometry analysis revealed that' even if cell growth was inhibited by all the compounds to some extent, bDtBPP showed the most severe effect and stoods out from the other two degradants investigated. Graphical abstract.

Controlling Electronic Transitions in Fullerene van der Waals Aggregates via Supramolecular Assembly.

Morphologies crucially determine the optoelectronic properties of organic semiconductors. Therefore, hierarchical and supramolecular approaches have been developed for targeted design of supramolecular ensembles of organic semiconducting molecules and performance improvement of, e.g., organic solar cells (OSCs), organic light emitting diodes (OLEDs), and organic field-effect transistors (OFETs). We demonstrate how the photonic properties of fullerenes change with the formation of van der Waals aggregates. We identified supramolecular structures with broadly tunable absorption in the visible spectral range and demonstrated how to form aggregates with targeted visible (vis) absorption. To control supramolecular structure formation, we functionalized the C60-backbone with polar (bis-polyethylene glycol malonate-MPEG) tails, thus yielding an amphiphilic fullerene derivative that self-assembles at interfaces. Aggregates of systematically tuned size were obtained from concentrating MPEGC60 in stearic acid matrices, while different supramolecular geometries were provoked via different thin film preparation methods, namely spin-casting and Langmuir-Blodgett (LB) deposition from an air-water interface. We demonstrated that differences in molecular orientation in LB films (C2v type point group aggregates) and spin-casting (stochastic aggregates) lead to huge changes in electronic absorption spectra due to symmetry and orientation reasons. These differences in the supramolecular structures, causing the different photonic properties of spin-cast and LB films, could be identified by means of quantum chemical calculations. Employing supramolecular assembly, we propounded that molecular symmetry in fullerene aggregates is extremely important in controlling vis absorption to harvest photons efficiently, when mixed with a donor molecule, thus improving active layer design and performance of OSCs.

Small molecules intercept Notch signaling and the early secretory pathway.

Notch signaling has a pivotal role in numerous cell-fate decisions, and its aberrant activity leads to developmental disorders and cancer. To identify molecules that influence Notch signaling, we screened nearly 17,000 compounds using automated microscopy to monitor the trafficking and processing of a ligand-independent Notch-enhanced GFP (eGFP) reporter. Characterization of hits in vitro by biochemical and cellular assays and in vivo using zebrafish led to five validated compounds, four of which induced accumulation of the reporter at the plasma membrane by inhibiting γ-secretase. One compound, the dihydropyridine FLI-06, disrupted the Golgi apparatus in a manner distinct from that of brefeldin A and golgicide A. FLI-06 inhibited general secretion at a step before exit from the endoplasmic reticulum (ER), which was accompanied by a tubule-to-sheet morphological transition of the ER, rendering FLI-06 the first small molecule acting at such an early stage in secretory traffic. These data highlight the power of phenotypic screening to enable investigations of central cellular signaling pathways.