A Practical General Method for the Preparation of Long Acenes

The field of long acenes, the narrowest of the zig-zag graphene nanoribbons, has been an area of significant interest in the past decade because of its potential applications in organic electronics, spintronics and plasmonics. However the low solubility and high reactivity of these compounds has so far hindered their preparation on large scales. We report here a concise strategy for the synthesis of higher acenes through Diels–Alder condensation of arynes with a protected tetraene ketone. After deprotection by cleavage of the ketal, the obtained monoketone precursors cleanly yield the corresponding acenes through quantitative cheletropic thermal decarbonylation in the solid state, at moderate temperatures of 155 to 205 °C. This approach allows the preparation of heptacene, benzo[a]hexacene, cis- and trans-dibenzopentacene and offers a valuable new method for the synthesis of even larger acenes.     

Functional silver nanostructured surfaces applied in SERS and SIMS

Present article deals with functionality of silver nanostructured surfaces prepared by potentiostatic electrochemical deposition on the paraffin impregnated graphite electrode as template‐free substrates. The effect of the electrodeposition conditions on two silver surface functions: analytical signal enhancement in Surface‐enhanced Raman spectroscopy and pre‐ionization function, applied in secondary ion mass spectrometry (SIMS) is reported. Functional silver nanostructured substrate was prepared at a potential ?850 mV with a deposition duration of 20 min. Analytical signal enhancement factors of 3.2 ×10⁵ for Raman peak at 649 cm^?1, 3.0×10⁵ for peak at 810 cm^?1 and 2.7×10⁵ for peak at 1539 cm^?1 were determined for Rhodamine 6G at deposited surface. Slight pre‐ionization effect has been observed in SIMS, and 1.2×10⁵ fold signal enhancement was established for fragment of Rhodamine 6G with m/z 429 (M‐CH₃‐Cl). Electrochemical preparation of nanostructures represents a step towards surface integration directly into miniaturized systems and sensors. Copyright © 2013 John Wiley & Sons, Ltd.     

Glycation sites of human plasma proteins are affected to different extents by hyperglycemic conditions in type 2 diabetes mellitus

Glucose can modify proteins in human blood, forming early glycation products (e.g., Amadori compounds), which can slowly degrade to advanced glycation endproducts (AGEs). AGEs contribute significantly to complications of diabetes mellitus and, thus, represent markers of advanced disease stages. They are, however, currently unsuitable for early diagnosis and therapeutic monitoring. Here, we report sensitive strategies to identify and relatively quantify protein glycation sites in human plasma samples obtained from type 2 diabetes mellitus (T2DM) patients and age-matched nondiabetic individuals using a bottom-up approach. Specifically, Amadori peptides were enriched from tryptic digests by boronic acid affinity chromatography, separated by reversed-phase chromatography, and analyzed on-line by high-resolution mass spectrometry. Among the 52 Amadori peptides studied here were 20 peptides resembling 19 glycation sites in six human proteins detected at statistically significantly higher levels in T2DM than in the normoglycemic controls. Four positions appeared to be unique for T2DM within the detection limit. All 19 glycation sites represent promising new biomarker candidates for early diagnosis of T2DM and adequate therapeutic control, as they may indicate early metabolic changes preceding T2DM. Graphical Abstract

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Synthesis and Biochemical Evaluation of Warhead-Decorated Psoralens as (Immuno)Proteasome Inhibitors

The immunoproteasome is a multicatalytic protease that is predominantly expressed in cells of hematopoietic origin. Its elevated expression has been associated with autoimmune diseases, various types of cancer, and inflammatory diseases. Selective inhibition of its catalytic activities is therefore a viable approach for the treatment of these diseases. However, the development of immunoproteasome-selective inhibitors with non-peptidic scaffolds remains a challenging task. We previously reported 7H-furo[3,2-g]chromen-7-one (psoralen)-based compounds with an oxathiazolone warhead as selective inhibitors of the chymotrypsin-like (β5i) subunit of immunoproteasome. Here, we describe the influence of the electrophilic warhead variations at position 3 of the psoralen core on the inhibitory potencies. Despite mapping the chemical space with different warheads, all compounds showed decreased inhibition of the β5i subunit of immunoproteasome in comparison to the parent oxathiazolone-based compound. Although suboptimal, these results provide crucial information about structure–activity relationships that will serve as guidance for the further design of (immuno)proteasome inhibitors.     

Rigidity percolation in particle-laden foams

We study the viscoelastic behavior of aqueous foam mixed with solid noncolloidal particles. We show that adding a tiny amount of grains can enhance the elastic and loss shear moduli by more than 1 order of magnitude. The scaling of these moduli with solid volume fraction is in qualitative agreement with that predicted by an effective-medium rigidity percolation model. We present a simple model, based on capillary attraction, to explain the particle-size dependence of the threshold.     

Need for database extension for reliable identification of bacteria from extreme environments using MALDI TOF mass spectrometry

The ability of MALDI TOF MS (matrix-assisted laser desorption ionisation time-of-flight mass spectrometry) to identify cultivable microflora from two waste disposal sites from non-ferrous metal industry was analysed. Despite the harsh conditions (extreme pH values and heavy metal content in red mud disposal site from aluminium production or high heavy metal content in nickel sludge), relatively high numbers of bacteria were recovered. In both environments, the bacterial community was dominated by Gram-positive bacteria, especially by actinobacteria. High-quality MALDI TOF mass spectra were obtained but most of the bacteria isolates could be not identified using MALDI Biotyper software. The overall identification rate was lower than 20 %; in two of the environments tested identification rates were lower than 10 %. As a dominant bacterial species, Microbacterium spp. in drainage water from an aluminium red mud disposal site near ?iar nad Hronom, Bacillus spp. in red mud samples from the same site, and Arthrobacter spp. from nickel smelter sludge near Sereï were identified by a combination of the Biolog system and 16S rRNA sequence analysis. As the primary focus of the MALDI TOF MS-based methodology is directed towards medically important bacteria, reference database spectra expansion and refinement are needed to improve the ability of MALDI TOF MS to identify environmental bacteria, especially those from extreme environments.     

Stability and Removal of Benzophenone-Type UV Filters from Water Matrices by Advanced Oxidation Processes

Benzophenone (BP) type UV filters are common environmental contaminants that are posing a growing health concern due to their increasing presence in water. Different studies have evidenced the presence of benzophenones (BP, BP-1, BP-2, BP-3, BP-4, BP-9, HPB) in several environmental matrices, indicating that conventional technologies of water treatment are not able to remove them. It has also been reported that these compounds could be associated with endocrine-disrupting activities, genotoxicity, and reproductive toxicity. This review focuses on the degradation kinetics and mechanisms of benzophenone-type UV filters and their degradation products (DPs) under UV and solar irradiation and in UV-based advanced oxidation processes (AOPs) such as UV/H₂O₂, UV/persulfate, and the Fenton process. The effects of various operating parameters, such as UV irradiation including initial concentrations of H₂O₂, persulfate, and Fe²⁺, on the degradation of tested benzophenones from aqueous matrices, and conditions that allow higher degradation rates to be achieved are presented. Application of nanoparticles such as TiO₂, PbO/TiO₂, and Sb₂O₃/TiO₂ for the photocatalytic degradation of benzophenone-type UV filters was included in this review.     

Structural diversity of isothiocyanato Cd(II) and Zn(II) Girard’s T hydrazone complexes in solution and solid state: effect of H-bonding on coordination number and supramolecular assembly of Cd(II) complex in solid state

The isothiocyanato Zn(II) complex (1) and mixed isothiocyanato/thiocyanato Cd(II) complex (2) with the condensation product of 2-acetylpyridine and trimethylammoniumacetohydrazide chloride (Girard’s T reagent) (HLCl) were investigated both experimentally and theoretically. The crystal structures of both complexes showed tridentate N₂O coordination of hydrazine ligand. In complex 1 square-pyramidal coordination surrounding of Zn(II) consists of deprotonated hydrazone ligand and two isothiocyanato ligands, while in octahedral Cd(II) complex ligand is coordinated without deprotonation as a positively charged species and coordination geometry is completed with two N-coordinated and one S-coordinated NCS^? anions. NMR spectroscopy and molar conductivity results for Cd(II) and Zn(II) complexes indicated their instability in solution. DFT calculations were performed to explain coordination preference and stability of complexes 1 and 2 in solid state and in solution. The obtained Cd(II) complex is the first reported mononuclear pseudohalide/halide Cd(II) complex with quinoline-/pyridine-based hydrazone ligands possessing octahedral geometry in solid state. In this complex, H-bonding has significant impact on coordination number and supramolecular assembly in solid state.     

Zinc-phosphate nanoparticles with reversibly attached TNF-α analogs: an interesting concept for potential use in active immunotherapy

The authors’ intention was to prepare nanometer-sized zinc-phosphate nanoparticles that would be capable of binding histidine-rich TNF-α analogs onto their surface via a coordinative bond. Zinc-phosphate nanoparticles with a size of around 60 nm were prepared by a wet precipitation method and characterized using SEM, EDX, XRD, and DLS. First, BSA was bound as a testing protein, afterward two TNF-α analogs with decreased activity were bound to the described nanoparticles. The efficiency of binding and the existence of coordinative bond were confirmed with SDS-PAGE analysis. During binding, particle storage, and release experiments, the prepared TNF-α analogs retained their biological activity—hence the epitopes necessary for formation of antibodies stayed intact. The particle size did not change within a period of 2 weeks. No significant agglomeration was observed, the particles could be quickly dispersed in ultrasound. The present nanoparticles and the general approach of coordinative binding are widely applicable for natural and engineered histidine-rich proteins. The nanoparticles bearing appropriate TNF-α analogs could also be potentially used for active immunotherapy to tackle the chronic inflammatory diseases associated with pathogenically elevated levels of TNF-α.