TY - JOUR A1 - Lu, Yong-Ping A1 - Reichetzeder, Christoph A1 - Prehn, Cornelia A1 - von Websky, Karoline A1 - Slowinski, Torsten A1 - Chen, You-Peng A1 - Yin, Liang-Hong A1 - Kleuser, Burkhard A1 - Yang, Xue-Song A1 - Adamski, Jerzy A1 - Hocher, Berthold T1 - Fetal serum metabolites are independently associated with Gestational diabetes mellitus JF - Cellular physiology and biochemistry : international journal of experimental cellular physiology, biochemistry and pharmacology N2 - Background/Aims: Gestational diabetes (GDM) might be associated with alterations in the metabolomic profile of affected mothers and their offspring. Until now, there is a paucity of studies that investigated both, the maternal and the fetal serum metabolome in the setting of GDM. Mounting evidence suggests that the fetus is not just passively affected by gestational disease but might play an active role in it. Metabolomic studies performed in maternal blood and fetal cord blood could help to better discern distinct fetal from maternal disease interactions. Methods: At the time of birth, serum samples from mothers and newborns (cord blood samples) were collected and screened for 163 metabolites utilizing tandem mass spectrometry. The cohort consisted of 412 mother/child pairs, including 31 cases of maternal GDM. Results: An initial non-adjusted analysis showed that eight metabolites in the maternal blood and 54 metabolites in the cord blood were associated with GDM. After Benjamini-Hochberg (BH) procedure and adjustment for confounding factors for GDM, fetal phosphatidylcholine acyl-alkyl C 32:1 and proline still showed an independent association with GDM. Conclusions: This study found metabolites in cord blood which were associated with GDM, even after adjustment for established risk factors of GDM. To the best of our knowledge, this is the first study demonstrating an independent association between fetal serum metabolites and maternal GDM. Our findings might suggest a potential effect of the fetal metabolome on maternal GDM. (c) 2018 The Author(s) Published by S. Karger AG, Basel KW - Gestational diabetes KW - Metabolomics KW - Phosphatidylcholine acyl-alkyl C 32:1 KW - Proline Y1 - 2018 U6 - https://doi.org/10.1159/000487119 SN - 1015-8987 SN - 1421-9778 VL - 45 IS - 2 SP - 625 EP - 638 PB - Karger CY - Basel ER - TY - JOUR A1 - Lu, Yong-Ping A1 - Reichetzeder, Christoph A1 - Prehn, Cornelia A1 - Yin, Liang-Hong A1 - Yun, Chen A1 - Zeng, Shufei A1 - Chu, Chang A1 - Adamski, Jerzy A1 - Hocher, Berthold T1 - Cord blood Lysophosphatidylcholine 16:1 is positively associated with birth weight JF - Cellular physiology and biochemistry : international journal of experimental cellular physiology, biochemistry and pharmacology N2 - Background/Aims: Impaired birth outcomes, like low birth weight, have consistently been associated with increased disease susceptibility to hypertension in later life. Alterations in the maternal or fetal metabolism might impact on fetal growth and influence birth outcomes. Discerning associations between the maternal and fetal metabolome and surrogate parameters of fetal growth could give new insight into the complex relationship between intrauterine conditions, birth outcomes, and later life disease susceptibility. Methods: Using flow injection tandem mass spectrometry, targeted metabolomics was performed in serum samples obtained from 226 mother/child pairs at delivery. Associations between neonatal birth weight and concentrations of 163 maternal and fetal metabolites were analyzed. Results: After FDR adjustment using the Benjamini-Hochberg procedure lysophosphatidylcholines (LPC) 14:0, 16:1, and 18:1 were strongly positively correlated with birth weight. In a stepwise linear regression model corrected for established confounding factors of birth weight, LPC 16: 1 showed the strongest independent association with birth weight (CI: 93.63 - 168.94; P = 6.94x10(-11)). The association with birth weight was stronger than classical confounding factors such as offspring sex (CI: - 258.81- -61.32; P = 0.002) and maternal smoking during pregnancy (CI: -298.74 - -29.51; P = 0.017). Conclusions: After correction for multiple testing and adjustment for potential confounders, LPC 16:1 showed a very strong and independent association with birth weight. The underlying molecular mechanisms linking fetal LPCs with birth weight need to be addressed in future studies. (c) 2018 The Author(s) Published by S. Karger AG, Basel KW - Metabolomics KW - Lysophosphatidylcholine KW - Birth Weight KW - DOHaD KW - Hypertension KW - Type 2 Diabetes Y1 - 2018 U6 - https://doi.org/10.1159/000487118 SN - 1015-8987 SN - 1421-9778 VL - 45 IS - 2 SP - 614 EP - 624 PB - Karger CY - Basel ER - TY - JOUR A1 - Muiva-Mutisya, Lois M. A1 - Atilaw, Yoseph A1 - Heydenreich, Matthias A1 - Koch, Andreas A1 - Akala, Hoseah M. A1 - Cheruiyot, Agnes C. A1 - Brown, Matthew L. A1 - Irungu, Beatrice A1 - Okalebo, Faith A. A1 - Derese, Solomon A1 - Mutai, Charles A1 - Yenesew, Abiy T1 - Antiplasmodial prenylated flavanonols from Tephrosia subtriflora JF - Natural Product Research N2 - The CH2Cl2/MeOH (1:1) extract of the aerial parts of Tephrosia subtriflora afforded a new flavanonol, named subtriflavanonol (1), along with the known flavanone spinoflavanone B, and the known flavanonols MS-II (2) and mundulinol. The structures were elucidated by the use of NMR spectroscopy and mass spectrometry. The absolute configuration of the flavanonols was determined based on quantum chemical ECD calculations. In the antiplasmodial assay, compound 2 showed the highest activity against chloroquine-sensitive Plasmodiumfalciparum reference clones (D6 and 3D7), artemisinin-sensitive isolate (F32-TEM) as well as field isolate (KSM 009) with IC50 values 1.4-4.6M without significant cytotoxicity against Vero and HEp2 cell lines (IC50>100M). The new compound (1) showed weak antiplasmodial activity, IC50 12.5-24.2M, but also showed selective anticancer activity against HEp2 cell line (CC50 16.9M). [GRAPHICS] . KW - Tephrosia subtriflora KW - Leguminosae KW - prenylated flavanonol KW - subtriflavanonol KW - antiplasmodial KW - cytotoxicity Y1 - 2018 U6 - https://doi.org/10.1080/14786419.2017.1353510 SN - 1478-6419 SN - 1478-6427 VL - 32 IS - 12 SP - 1407 EP - 1414 PB - Routledge, Taylor & Francis Group CY - Abingdon ER - TY - JOUR A1 - Krüger-Genge, Anne A1 - Schulz, Christian A1 - Kratz, Karl A1 - Lendlein, Andreas A1 - Jung, Friedrich T1 - Comparison of two substrate materials used as negative control in endothelialization studies BT - Glass versus polymeric tissue culture plate JF - Clinical hemorheology and microcirculation : blood flow and vessels N2 - The endothelialization of synthetic surfaces applied as cardiovascular implant materials is an important issue to ensure the anti-thrombotic quality of a biomaterial. However, the rapid and constant development of a functionallycon-fluent endothelial cell monolayer is challenging. In order to investigate the compatibility of potential implant materials with endothelial cells several in vitro studies are performed. Here, glass and tissue culture plates (TCP) are often used as reference materials for in vitro pre-testing. However, a direct comparison of both substrates is lacking. Therefore, a comparison of study results is difficult, since results are often related to various reference materials. In this study, the endothelialization of glass and TCP was investigated in terms of adherence, morphology, integrity, viability and function using human umbilical vein endothelial cells (HUVEC). On both substrates an almost functionally confluent HUVEC monolayer was developed after nine days of cell seeding with clearly visible cell rims, decreased stress fiber formation and a pronounced marginal filament band. The viability of HUVEC was comparable for both substrates nine days after cell seeding with only a few dead cells. According to that, the cell membrane integrity as well as the metabolic activity showed no differences between TCP and glass. However, a significant difference was observed for the secretion of IL-6 and IL-8. The concentration of both cytokines, which are associated with migratory activity, was increased in the supernatant of HUVEC seeded on TCP. This result matches well with the slightly increased number of adherent HUVEC on TCP. In conclusion, these findings indicate that both reference materials are almost comparable and can be used equivalently as control materials in in vitro endothelialization studies. KW - Negative control KW - endothelial cells KW - glass KW - TCP KW - reference Y1 - 2018 U6 - https://doi.org/10.3233/CH-189904 SN - 1386-0291 SN - 1875-8622 VL - 69 IS - 3 SP - 437 EP - 445 PB - IOS Press CY - Amsterdam ER - TY - JOUR A1 - Krüger-Genge, A. A1 - Braune, S. A1 - Walter, M. A1 - Krengel, M. A1 - Kratz, K. A1 - Küpper, J. H. A1 - Lendlein, Andreas A1 - Jung, Friedrich T1 - Influence of different surface treatments of poly(n-butyl acrylate) networks on fibroblasts adhesion, morphology and viability JF - Clinical hemorheology and microcirculation : blood flow and vessels N2 - BACKGROUND: Physical and chemical characteristics of implant materials determine the fate of long-term cardiovascular devices. However, there is still a lack of fundamental understanding of the molecular mechanisms occurring in the material-tissue interphase. In a previous study, soft covalently crosslinked poly(n-butyl acrylate) networks (cPnBA) were introduced as sterilizable, non-toxic and immuno-compatible biomaterials with mechanical properties adjustable to blood vessels. Here we study the influence of different surface treatments in particular oxygen plasma modification and fibrinogen deposition as well as a combinatorial approach on the adhesion and viability of fibroblasts. RESULTS: Compared to non-treated cPnBAs the advancing water-contact angles were found to be reduced after all surface modifications (p<0.05, each), while lowest values were observed after the combined surface treatment (OPT+FIB). The latter differed significantly from the single OPT and FIB. The number of adherent fibroblasts and their adherence behavior differed on both pristine cPnBA networks. The fibroblast density on cPnBA04 was 743 +/- 434 cells. mm(-2), was about 6.5 times higher than on cPnBA73 with 115 +/- 73 cells. mm(-2). On cPnBA04 about 20% of the cells were visible as very small, round and buckled cells while all other cells were in a migrating status. On cPnBA73, nearly 50% of fibroblasts were visible as very small, round and buckled cells. The surface functionalization either using oxygen plasma treatment or fibrinogen coating led to a significant increase of adherent fibroblasts, particularly the combination of both techniques, for both cPnBA networks. It is noteworthy to mention that the fibrinogen coating overruled the characteristics of the pristine surfaces; here, the fibroblast densities after seeding were identical for both cPnBAnetworks. Thus, the binding rather depended on the fibrinogen coating than on the substrate characteristics anymore. While the integrity of the fibroblasts membrane was comparable for both polymers, the MTS tests showed a decreased metabolic activity of the fibroblasts on cPnBA. CONCLUSION: The applied surface treatments of cPnBA successfully improved the adhesion of viable fibroblasts. Under resting conditions as well as after shearing the highest fibroblast densities were found on surfaces with combined post-treatment. KW - Biomaterial KW - poly(n-butyl acrylate) KW - fibroblast KW - oxygen plasma KW - fibrinogen KW - cell adhesion KW - focal adhesion KW - actin cytoskeleton KW - viability Y1 - 2018 U6 - https://doi.org/10.3233/CH-189130 SN - 1386-0291 SN - 1875-8622 VL - 69 IS - 1-2 SP - 305 EP - 316 PB - IOS Press CY - Amsterdam ER - TY - JOUR A1 - Kumar, Reddi K. A1 - Heuchel, Matthias A1 - Kratz, Karl A1 - Lendlein, Andreas A1 - Jankowski, Joachim A1 - Tetali, Sarada D. T1 - Effects of extracts prepared from modified porous poly(ether imide) microparticulate absorbers on cytotoxicity, macrophage differentiation and proinflammatory behavior of human monocytic (THP-1) cells JF - Clinical hemorheology and microcirculation : blood flow and vessels N2 - Remaining uremic toxins in the blood of chronic renal failure patients represent one central challenge in hemodialysis therapies. Highly porous poly(ether imide) (PEI) microparticles have been recently introduced as candidate absorber materials, which show a high absorption capacity for uremic toxins and allow hydrophilic surface modification suitable for minimization of serum protein absorption. In this work, the effects of extracts prepared from PEI microparticles modified by nucleophilic reaction with low molecular weight polyethylene imine (Pei) or potassium hydroxide (KOH), on human monocytic (THP-1) cells are studied. The obtained results suggested that the extracts of Pei and KOH modified PEI absorbers have no negative effect on THP-1 cell viability and do not initiate the critical differentiation towards macrophages. The extracts did not enhance transcript or protein levels of investigated proinflammatory markers in THP-1 cells, namely, TNF alpha, MCP1, IL6 and IL8. Based on these findings such modified PEI microparticles should be qualified for further pre-clinical evaluation i.e. in an in vivo animal experiment. KW - Chronic kidney disease KW - hemodialysis KW - Inflammation KW - Porous poly(ether imide) microparticulate absorbers KW - THP-1 cells KW - Uremic toxins Y1 - 2018 U6 - https://doi.org/10.3233/CH-189112 SN - 1386-0291 SN - 1875-8622 VL - 69 IS - 1-2 SP - 175 EP - 185 PB - IOS Press CY - Amsterdam ER - TY - JOUR A1 - Giulbudagian, Michael A1 - Yealland, Guy A1 - Hönzke, S. A1 - Edlich, A. A1 - Geisendörfer, Birte A1 - Kleuser, Burkhard A1 - Hedtrich, Sarah A1 - Calderon, Marcelo T1 - Breaking the Barrier BT - potent anti-inflammatory activity following efficient topical delivery of etanercept using thermoresponsive nanogels JF - Theranostics N2 - Topical administration permits targeted, sustained delivery of therapeutics to human skin. Delivery to the skin, however, is typically limited to lipophilic molecules with molecular weight of < 500 Da, capable of crossing the stratum corneum. Nevertheless, there are indications protein delivery may be possible in barrier deficient skin, a condition found in several inflammatory skin diseases such as psoriasis, using novel nanocarrier systems. Methods: Water in water thermo-nanoprecipitation; dynamic light scattering; zeta potential measurement; nanoparticle tracking analysis; atomic force microscopy; cryogenic transmission electron microscopy; UV absorption; centrifugal separation membranes; bicinchoninic acid assay; circular dichroism; TNF alpha binding ELISA; inflammatory skin equivalent construction; human skin biopsies; immunohistochemistry; fluorescence microscopy; western blot; monocyte derived Langerhans cells; ELISA Results: Here, we report the novel synthesis of thermoresponsive nanogels (tNG) and the stable encapsulation of the anti-TNFa fusion protein etanercept (ETR) (similar to 150 kDa) without alteration to its structure, as well as temperature triggered release from the tNGs. Novel tNG synthesis without the use of organic solvents was conducted, permitting in situ encapsulation of protein during assembly, something that holds great promise for easy manufacture and storage. Topical application of ETR loaded tNGs to inflammatory skin equivalents or tape striped human skin resulted in efficient ETR delivery throughout the SC and into the viable epidermis that correlated with clear anti-inflammatory effects. Notably, effective ETR delivery depended on temperature triggered release following topical application. Conclusion: Together these results indicate tNGs hold promise as a biocompatible and easy to manufacture vehicle for stable protein encapsulation and topical delivery into barrier-deficient skin. KW - thermoresponsive-nanogel KW - topical KW - anti-inflammatory therapy KW - etanercept KW - skin equivalents Y1 - 2018 U6 - https://doi.org/10.7150/thno.21668 SN - 1838-7640 VL - 8 IS - 2 SP - 450 EP - 463 PB - Ivyspring International Publisher CY - Lake haven ER - TY - JOUR A1 - Zimmermann, Marc A1 - Grigoriev, Dmitry A1 - Puretskiy, Nikolay A1 - Böker, Alexander T1 - Characteristics of microcontact printing with polyelectrolyte ink for the precise preparation of patches on silica particles JF - RSC Advances N2 - This publication demonstrates the abilities of a precise and straightforward microcontact printing approach for the preparation of patchy silica particles. In a broad particle size range, it is possible to finely tune the number and parameters of three-dimensional patches like diameter and thickness using only polyethyleneimine ink, poly(dimethoxysilane) as stamp material and a suitable release solvent. Y1 - 2018 U6 - https://doi.org/10.1039/c8ra07955b SN - 2046-2069 VL - 8 IS - 69 SP - 39241 EP - 39247 PB - Royal Society of Chemistry CY - Cambridge ER - TY - GEN A1 - Ellis, S. C. A1 - Bauer, S. A1 - Bacigalupo, C. A1 - Bland-Hawthorn, J. A1 - Bryant, J. J. A1 - Case, S. A1 - Content, R. A1 - Fechner, T. A1 - Giannone, D. A1 - Haynes, R. A1 - Hernandez, E. A1 - Horton, A. J. A1 - Klauser, U. A1 - Lawrence, J. S. A1 - Leon-Saval, S. G. A1 - Lindley, E. A1 - Löhmannsröben, Hans-Gerd A1 - Min, S. -S. A1 - Pai, N. A1 - Roth, M. A1 - Shortridge, K. A1 - Waller, L. A1 - Xavier, Pascal A1 - Zhelem, Ross T1 - PRAXIS: an OH suppression optimised near infrared spectrograph T2 - Ground-based and Airborne Instrumentation for Astronomy VII N2 - The problem of atmospheric emission from OH molecules is a long standing problem for near-infrared astronomy. PRAXIS is a unique spectrograph which is fed by fibres that remove the OH background and is optimised specifically to benefit from OH-Suppression. The OH suppression is achieved with fibre Bragg gratings, which were tested successfully on the GNOSIS instrument. PRAXIS uses the same fibre Bragg gratings as GNOSIS in its first implementation, and will exploit new, cheaper and more efficient, multicore fibre Bragg gratings in the second implementation. The OH lines are suppressed by a factor of similar to 1000, and the expected increase in the signal-to-noise in the interline regions compared to GNOSIS is a factor of similar to 9 with the GNOSIS gratings and a factor of similar to 17 with the new gratings. PRAXIS will enable the full exploitation of OH suppression for the first time, which was not achieved by GNOSIS (a retrofit to an existing instrument that was not OH-Suppression optimised) due to high thermal emission, low spectrograph transmission and detector noise. PRAXIS has extremely low thermal emission, through the cooling of all significantly emitting parts, including the fore-optics, the fibre Bragg gratings, a long length of fibre, and the fibre slit, and an optical design that minimises leaks of thermal emission from outside the spectrograph. PRAXIS has low detector noise through the use of a Hawaii-2RG detector, and a high throughput through a efficient VPH based spectrograph. PRAXIS will determine the absolute level of the interline continuum and enable observations of individual objects via an IFU. In this paper we give a status update and report on acceptance tests. KW - Near infrared KW - spectroscopy KW - OH suppression KW - astrophotonics KW - fibre Bragg gratings Y1 - 2018 SN - 978-1-5106-1958-6 U6 - https://doi.org/10.1117/12.2311898 SN - 0277-786X SN - 1996-756X VL - 10702 PB - SPIE-INT Soc Optical Engineering CY - Bellingham ER - TY - JOUR A1 - Yarman, Aysu A1 - Kurbanoglu, Sevinc A1 - Jetzschmann, Katharina J. A1 - Ozkan, Sibel A. A1 - Wollenberger, Ulla A1 - Scheller, Frieder W. T1 - Electrochemical MIP-Sensors for Drugs JF - Current Medicinal Chemistry N2 - In order to replace bio-macromolecules by stable synthetic materials in separation techniques and bioanalysis biomimetic receptors and catalysts have been developed: Functional monomers are polymerized together with the target analyte and after template removal cavities are formed in the "molecularly imprinted polymer" (MIP) which resemble the active sites of antibodies and enzymes. Starting almost 80 years ago, around 1,100 papers on MIPs were published in 2016. Electropolymerization allows to deposit MIPs directly on voltammetric electrodes or chips for quartz crystal microbalance (QCM) and surface plasmon resonance (SPR). For the readout of MIPs for drugs amperometry, differential pulse voltammetry (DPV) and impedance spectroscopy (EIS) offer higher sensitivity as compared with QCM or SPR. Application of simple electrochemical devices allows both the reproducible preparation of MIP sensors, but also the sensitive signal generation. Electrochemical MIP-sensors for the whole arsenal of drugs, e.g. the most frequently used analgesics, antibiotics and anticancer drugs have been presented in literature and tested under laboratory conditions. These biomimetic sensors typically have measuring ranges covering the lower nano-up to millimolar concentration range and they are stable under extreme pH and in organic solvents like nonaqueous extracts. KW - Biomimetic sensors KW - molecularly imprinted polymers KW - drug sensors KW - drug imprinting KW - electropolymerization KW - electrochemical sensors Y1 - 2018 U6 - https://doi.org/10.2174/0929867324666171005103712 SN - 0929-8673 SN - 1875-533X VL - 25 IS - 33 SP - 4007 EP - 4019 PB - Bentham Science Publishers LTD CY - Sharjah ER - TY - JOUR A1 - Razzaq, Muhammad Yasar A1 - Behl, Marc A1 - Lendlein, Andreas T1 - Thermally-induced actuation of magnetic nanocomposites based on Oligo(ω-pentadecalactone) and covalently integrated magnetic nanoparticles JF - MRS advances: a journal of the Materials Research Society (MRS) N2 - The incorporation of inorganic particles in a polymer matrix has been established as a method to adjust the mechanical performance of composite materials. We report on the influence of covalent integration of magnetic nanoparticles (MNP) on the actuation behavior and mechanical performance of hybrid nanocomposite (H-NC) based shape-memory polymer actuators (SMPA). The H-NC were synthesized by reacting two types of oligo(ω-pentadecalactone) (OPDL) based precursors with terminal hydroxy groups, a three arm OPDL (3 AOPDL, Mn = 6000 g mol•1−1 ) and an OPDL (Mn =3300 g • mol−1 ) coated magnetite nanoparticle (Ø = 10 ± 2 nm), with a diisocyanate. These H-NC were compared to the homopolymer network regarding the actuation performance, contractual stress (σcontr) as well as thermal and mechanical properties. The melting range of the OPDL crystals (ΔTm,OPDL) was shifted in homo polymer networks from 36 ºC − 76 ºC to 41ºC − 81 °C for H-NC with 9 wt% of MNP content. The actuators were explored by variation of separating temperature (Tsep), which splits the OPDL crystalline domain into actuating and geometry determining segments. Tsep was varied in the melting range of the nanocomposites and the actuation capability and contractual stress (σcontr) of the nanocomposite actuators could be adjusted. The reversible strain (εrev) was decreased from 11 ± 0.3% for homo polymer network to 3.2±0.3% for H-NC9 with 9 wt% of MNP indicating a restraining effect of the MNP on chain mobility. The results show that the performance of H-NCs in terms of thermal and elastic properties can be tailored by MNP content, however for higher reversible actuation, lower MNP contents are preferable. Y1 - 2018 U6 - https://doi.org/10.1557/adv.2018.613 SN - 2059-8521 VL - 3 IS - 63 SP - 3783 EP - 3791 PB - Cambridge University Press CY - New York ER - TY - JOUR A1 - Krüger, Stefanie A1 - Schwarze, Michael A1 - Baumann, Otto A1 - Günter, Christina A1 - Bruns, Michael A1 - Kübel, Christian A1 - Szabo, Dorothee Vinga A1 - Meinusch, Rafael A1 - Bermudez, Veronica de Zea A1 - Taubert, Andreas T1 - Bombyx mori silk/titania/gold hybrid materials for photocatalytic water splitting BT - combining renewable raw materials with clean fuels JF - Beilstein journal of nanotechnology N2 - The synthesis, structure, and photocatalytic water splitting performance of two new titania (TiO2)/gold(Au)/Bombyx mori silk hybrid materials are reported. All materials are monoliths with diameters of up to ca. 4.5 cm. The materials are macroscopically homogeneous and porous with surface areas between 170 and 210 m(2)/g. The diameter of the TiO2 nanoparticles (NPs) - mainly anatase with a minor fraction of brookite - and the Au NPs are on the order of 5 and 7-18 nm, respectively. Addition of poly(ethylene oxide) to the reaction mixture enables pore size tuning, thus providing access to different materials with different photocatalytic activities. Water splitting experiments using a sunlight simulator and a Xe lamp show that the new hybrid materials are effective water splitting catalysts and produce up to 30 mmol of hydrogen per 24 h. Overall the article demonstrates that the combination of a renewable and robust scaffold such as B. mori silk with a photoactive material provides a promising approach to new monolithic photocatalysts that can easily be recycled and show great potential for application in lightweight devices for green fuel production. KW - Bombyx mori silk KW - gold KW - photocatalytic water splitting KW - titania Y1 - 2018 U6 - https://doi.org/10.3762/bjnano.9.21 SN - 2190-4286 VL - 9 SP - 187 EP - 204 PB - Beilstein-Institut zur Förderung der Chemischen Wissenschaften CY - Frankfurt, Main ER - TY - JOUR A1 - Schmidt, Bernd A1 - Schultze, Christiane T1 - A one-pot synthesis of pyranocoumarins through microwave-promoted propargyl claisen rearrangement/wittig olefination JF - European journal of organic chemistry N2 - The reaction between propargyl ethers of hydroxybenzaldehydes and the ylide ethyl (triphenylphosphoranylidene)acetate was carried out under microwave irradiation to regioselectively afford angular pyranocoumarins. The chromene and coumarin heterocyclic scaffolds were simultaneously formed in the same synthetic step without changing the reaction conditions. The natural products seselin, braylin, and dipetalolactone were among the products synthesized by this method. KW - Domino reactions KW - Alkynes KW - Arenes KW - Oxygen heterocycles KW - Microwave chemistry KW - Rearrangement Y1 - 2017 SN - 1434-193X SN - 1099-0690 VL - 2018 IS - 2 SP - 223 EP - 227 PB - Wiley-VCH Verl. CY - Weinheim ER - TY - JOUR A1 - Xiong, Tao A1 - Włodarczyk, Radosław Stanisław A1 - Gallandi, Lukas A1 - Körzdörfer, Thomas A1 - Saalfrank, Peter T1 - Vibrationally resolved photoelectron spectra of lower diamondoids BT - a time-dependent approach JF - The journal of chemical physics : bridges a gap between journals of physics and journals of chemistry N2 - Vibrationally resolved lowest-energy bands of the photoelectron spectra (PES) of adamantane, diamantane, and urotropine were simulated by a time-dependent correlation function approach within the harmonic approximation. Geometries and normal modes for neutral and cationic molecules were obtained from B3LYP hybrid density functional theory (DFT). It is shown that the simulated spectra reproduce the experimentally observed vibrational finestructure (or its absence) quite well. Origins of the finestructure are discussed and related to recurrences of autocorrelation functions and dominant vibrations. Remaining quantitative and qualitative errors of the DFT-derived PES spectra refer to (i) an overall redshift by ∼0.5 eV and (ii) the absence of satellites in the high-energy region of the spectra. The former error is shown to be due to the neglect of many-body corrections to ordinary Kohn-Sham methods, while the latter has been argued to be due to electron-nuclear couplings beyond the Born-Oppenheimer approximation [Gali et al., Nat. Commun. 7, 11327 (2016)]. Y1 - 2018 U6 - https://doi.org/10.1063/1.5012131 SN - 0021-9606 SN - 1089-7690 VL - 148 IS - 4 PB - American Institute of Physics CY - Melville ER - TY - JOUR A1 - Hesse, Julia A1 - Klier, Dennis Tobias A1 - Sgarzi, Massimo A1 - Nsubuga, Anne A1 - Bauer, Christoph A1 - Grenzer, Joerg A1 - Hübner, Rene A1 - Wislicenus, Marcus A1 - Joshi, Tanmaya A1 - Kumke, Michael Uwe A1 - Stephan, Holger T1 - Rapid Synthesis of Sub-10nm Hexagonal NaYF4-Based Upconverting Nanoparticles using Therminol((R))66 JF - ChemistryOpen : including thesis treasury N2 - We report a simple one-pot method for the rapid preparation of sub-10nm pure hexagonal (-phase) NaYF4-based upconverting nanoparticles (UCNPs). Using Therminol((R))66 as a co-solvent, monodisperse UCNPs could be obtained in unusually short reaction times. By varying the reaction time and reaction temperature, it was possible to control precisely the particle size and crystalline phase of the UCNPs. The upconversion (UC) luminescence properties of the nanocrystals were tuned by varying the concentrations of the dopants (Nd3+ and Yb3+ sensitizer ions and Er3+ activator ions). The size and phase-purity of the as-synthesized core and core-shell nanocrystals were assessed by using complementary transmission electron microscopy, dynamic light scattering, X-ray diffraction, and small-angle X-ray scattering studies. In-depth photophysical evaluation of the UCNPs was pursued by using steady-state and time-resolved luminescence spectroscopy. An enhancement in the UC intensity was observed if the nanocrystals, doped with optimized concentrations of lanthanide sensitizer/activator ions, were further coated with an inert/active shell. This was attributed to the suppression of surface-related luminescence quenching effects. KW - core-shell materials KW - lanthanides KW - nanostructures KW - photoluminescence KW - upconversion Y1 - 2018 U6 - https://doi.org/10.1002/open.201700186 SN - 2191-1363 VL - 7 IS - 2 SP - 159 EP - 168 PB - Wiley-VCH CY - Weinheim ER - TY - JOUR A1 - Yaouba, Souaibou A1 - Koch, Andreas A1 - Guantai, Eric M. A1 - Derese, Solomon A1 - Irungu, Beatrice A1 - Heydenreich, Matthias A1 - Yenesew, Abiy T1 - Alkenyl cyclohexanone derivatives from Lannea rivae and Lannea schweinfurthii JF - Phytochemistry letters / Phytochemical Society of Europe N2 - Phytochemical investigation of the CH2Cl2/MeOH (1:1) extract of the roots of Lannea rivae (Chiov) Sacleux (Anacardiaceae) led to the isolation of a new alkenyl cyclohexenone derivative: (4R,6S)-4,6-dihydroxy-6-((Z)-nonadec-14′-en-1-yl)cyclohex-2-en-1-one (1), and a new alkenyl cyclohexanol derivative: (2S*,4R*,5S*)-2,4,5-trihydroxy-2-((Z)-nonadec-14′-en-1-yl)cyclohexanone (2) along with four known compounds, namely epicatechin gallate, taraxerol, taraxerone and β-sitosterol; while the stem bark afforded two known compounds, daucosterol and lupeol. Similar investigation of the roots of Lannea schweinfurthii (Engl.) Engl. led to the isolation of four known compounds: 3-((E)-nonadec-16′-enyl)phenol, 1-((E)-heptadec-14′-enyl)cyclohex-4-ene-1,3-diol, catechin, and 1-((E)-pentadec-12′-enyl)cyclohex-4-ene-1,3-diol. The structures of the isolated compounds were determined by NMR spectroscopy and mass spectrometry. The absolute configuration of compound 1 was established by quantum chemical ECD calculations. In an antibacterial activity assay using the microbroth kinetic method, compound 1 showed moderate activity against Escherichia coli while compound 2 exhibited moderate activity against Staphylococcus aureus. Compound 1 also showed moderate activity against E. coli using the disc diffusion method. The roots extract of L. rivae was notably cytotoxic against both the DU-145 prostate cancer cell line and the Vero mammalian cell line (CC50 = 5.24 and 5.20 μg/mL, respectively). Compound 1 was also strongly cytotoxic against the DU-145 cell line (CC50 = 0.55 μg/mL) but showed no observable cytotoxicity (CC50 > 100 μg/mL) against the Vero cell line. The roots extract of L. rivae and L. schweinfurthii, epicatechin gallate as well as compound 1 exhibited inhibition of carageenan-induced inflammation. KW - Lannea rivae KW - Lannea schweinfurthii KW - Alkenyl cyclohexenone KW - Alkenyl cyclohexanone KW - Anti-inflammatory KW - Cytotoxicity KW - Antimicrobial Y1 - 2017 U6 - https://doi.org/10.1016/j.phytol.2017.12.001 SN - 1874-3900 SN - 1876-7486 VL - 23 SP - 141 EP - 148 PB - Elsevier CY - Amsterdam ER - TY - JOUR A1 - Dai, Xiaolin A1 - Mate, Diana M. A1 - Glebe, Ulrich A1 - Garakani, Tayebeh Mirzaei A1 - Körner, Andrea A1 - Schwaneberg, Ulrich A1 - Böker, Alexander T1 - Sortase-mediated ligation of purely artificial building blocks JF - Polymers N2 - Sortase A (SrtA) from Staphylococcus aureus has been often used for ligating a protein with other natural or synthetic compounds in recent years. Here we show that SrtA-mediated ligation (SML) is universally applicable for the linkage of two purely artificial building blocks. Silica nanoparticles (NPs), poly(ethylene glycol) and poly(N-isopropyl acrylamide) are chosen as synthetic building blocks. As a proof of concept, NP-polymer, NP-NP, and polymer-polymer structures are formed by SrtA catalysis. Therefore, the building blocks are equipped with the recognition sequence needed for SrtA reaction-the conserved peptide LPETG-and a pentaglycine motif. The successful formation of the reaction products is shown by means of transmission electron microscopy (TEM), matrix assisted laser desorption ionization-time of flight mass spectrometry (MALDI-ToF MS), and dynamic light scattering (DLS). The sortase catalyzed linkage of artificial building blocks sets the stage for the development of a new approach to link synthetic structures in cases where their synthesis by established chemical methods is complicated. KW - sortase-mediated ligation KW - enzymes KW - block copolymers KW - nanoparticles Y1 - 2018 U6 - https://doi.org/10.3390/polym10020151 SN - 2073-4360 VL - 10 IS - 2 PB - MDPI CY - Basel ER - TY - JOUR A1 - Sun, Fu A1 - Osenberg, Markus A1 - Dong, Kang A1 - Zhou, Dong A1 - Hilger, Andre A1 - Jafta, Charl J. A1 - Risse, Sebastian A1 - Lu, Yan A1 - Markoetter, Henning A1 - Manke, Ingo T1 - Correlating Morphological Evolution of Li Electrodes with Degrading Electrochemical Performance of Li/LiCoO2 and Li/S Battery Systems BT - Investigated by Synchrotron X-ray Phase Contrast Tomography JF - ACS energy letters / American Chemical Society N2 - Efficient Li utilization is generally considered to be a prerequisite for developing next-generation energy storage systems (ESSs). However, uncontrolled growth of Li microstructures (LmSs) during electrochemical cycling has prevented its practical commercialization. Herein, we attempt to understand the correlation of morphological evolution of Li electrodes with degrading electrochemical performances of Li/LiCoO2 and Li/S systems by synchrotron X-ray phase contrast tomography technique. It was found that the continuous transformation of the initial dense Li bulk to a porous lithium interface (PL1) structure intimately correlates with the gradually degrading overall cell performance of these two systems. Additionally, the formation mechanism of the PLI and its correlation with previously reported inwardly growing LmS and the lithium-reacted region have been intensively discussed. The information that we gain herein is complementary to previous investigations and may provide general insights into understanding of degradation mechanisms of Li metal anodes and also provide highly needed guidelines for effective design of reliable next-generation Li metal-based ESSs. Y1 - 2018 U6 - https://doi.org/10.1021/acsenergylett.7b01254 SN - 2380-8195 VL - 3 IS - 2 SP - 356 EP - 365 PB - American Chemical Society CY - Washington ER - TY - JOUR A1 - Schmidt, Bernd A1 - Petersen, Monib H. A1 - Braun, Diana T1 - Bidirectional Synthesis of 6-Acetoxy-5-hexadecanolide, the Mosquito Oviposition Pheromone of Culex quinquefasciatus, from a C-2-Symmetric Building Block Using Olefin Metathesis Reactions JF - The journal of organic chemistry N2 - (5R,6S)-6-Acetoxy-5-hexadecanolide (MOP) is the oviposition pheromone of the mosquito Cx. quinquefasciatus, a vector of pathogens causing a variety of tropical diseases. We describe and evaluate herein three syntheses of MOP starting from mannitol-derived (3R,4R)-hexa-1,5-diene-3,4-diol. This C-2-symmetric building block is elaborated through bidirectional olefin metathesis reactions into 6-epi-MOP, which was converted into MOP via Mitsunobu inversion. The shortest of the three routes makes use of two sequential cross-metathesis reactions and an assisted tandem catalytic olefin reduction, induced by an in situ conversion of a Ru-carbene to a Ru-hydride. Y1 - 2018 U6 - https://doi.org/10.1021/acs.joc.7b02944 SN - 0022-3263 VL - 83 IS - 3 SP - 1627 EP - 1633 PB - American Chemical Society CY - Washington ER - TY - JOUR A1 - Kleinpeter, Erich A1 - Koch, Andreas T1 - Paramagnetic ring current effects in anti-aromatic structures subject to substitution/annelation quantified by spatial magnetic properties (TSNMRS) JF - Tetrahedron N2 - The spatial magnetic properties, through-space NMR shieldings (TSNMRS), of the typically anti-aromatic cyclopentadienyl cation, cyclobutadiene, pentalene, s-indacene and of substituted/annelated analogues of the latter structures have been calculated using the CIAO perturbation method employing the nucleus independent chemical shift (NICS) concept and visualized as iso-chemical-shielding surfaces (ICSS) of various size and direction. The TSNMRS values were employed to visualize and quantify the dia(para) magnetic ring current effects in the studied compounds. The interplay of dia(para)magnetic ring current effects due to substitution/annelation caused by heavy exo-cyclic n,pi-electron delocalization can be qualified. KW - Aromaticity KW - Anti-aromaticity KW - Through-space NMR shieldings (TSNMRS) KW - GIAO KW - NICS KW - Annelation effect Y1 - 2018 U6 - https://doi.org/10.1016/j.tet.2017.12.020 SN - 0040-4020 VL - 74 IS - 7 SP - 700 EP - 710 PB - Elsevier CY - Oxford ER - TY - JOUR A1 - Chen, Ye A1 - Song, Qilei A1 - Zhao, Junpeng A1 - Gong, Xiangjun A1 - Schlaad, Helmut A1 - Zhang, Guangzhao T1 - Betulin-Constituted multiblock amphiphiles for broad-spectrum protein resistance JF - ACS applied materials & interfaces N2 - Multiblock-like amphiphilic polyurethanes constituted by poly(ethylene oxide) and biosourced betulin are designed for antifouling and synthesized by a convenient organocatalytic route comprising tandem chain-growth and step-growth polymerizations. The doping density of betulin (D-B) in the polymer chain structure is readily varied by a mixed-initiator strategy. The spin-coated polymer films exhibit unique nanophase separation and protein resistance behaviors. Higher D-B leads to enhanced surface hydrophobicity and, unexpectedly, improved protein resistance. It is found that the surface holds molecular-level heterogeneity when D-B is substantially high due to restricted phase separation; therefore, broad-spectrum protein resistance is achieved despite considerable surface hydrophobicity. As D-B decreases, the distance between adjacent betulin units increases so that hydrophobic nanodomains are formed, which provide enough landing areas for relatively small-sized proteins to adsorb on the surface. KW - amphiphilic surface KW - antifouling KW - multiblock copolymer KW - organocatalytic polymerization KW - renewable resource Y1 - 2018 U6 - https://doi.org/10.1021/acsami.7b16255 SN - 1944-8244 VL - 10 IS - 7 SP - 6593 EP - 6600 PB - American Chemical Society CY - Washington ER - TY - JOUR A1 - Heinze, Mandy A1 - Hanschen, Franziska S. A1 - Wiesner-Reinhold, Melanie A1 - Baldermann, Susanne A1 - Gräfe, Jan A1 - Schreiner, Monika A1 - Neugart, Susanne T1 - Effects of Developmental Stages and Reduced UVB and Low UV Conditions on Plant Secondary Metabolite Profiles in Pak Choi (Brassica rapa subsp chinensis) JF - Journal of agricultural and food chemistry : a publication of the American Chemical Society N2 - Pak choi (Brassica rapa subsp. chinensis) is rich in secondary metabolites and contains numerous antioxidants, including flavonoids; hydroxycinnamic acids; carotenoids; chlorophylls; and glucosinolates, which can be hydrolyzed to epithionitriles, nitriles, or isothiocyanates. Here, we investigate the effect of reduced exposure to ultraviolet B (UVB) and UV (UVA and UVB) light at four different developmental stages of pak choi. We found that both the plant morphology and secondary metabolite profiles were affected by reduced exposure to UVB and UV, depending on the plant’s developmental stage. In detail, mature 15- and 30-leaf plants had higher concentrations of flavonoids, hydroxycinnamic acids, carotenoids, and chlorophylls, whereas sprouts contained high concentrations of glucosinolates and their hydrolysis products. Dry weights and leaf areas increased as a result of reduced UVB and low UV. For the flavonoids and hydroxycinnamic acids in 30-leaf plants, less complex compounds were favored, for example, sinapic acid acylated kaempferol triglycoside instead of the corresponding tetraglycoside. Moreover, also in 30-leaf plants, zeaxanthin, a carotenoid linked to protection during photosynthesis, was increased under low UV conditions. Interestingly, most glucosinolates were not affected by reduced UVB and low UV conditions. However, this study underlines the importance of 4-(methylsulfinyl)butyl glucosinolate in response to UVA and UVB exposure. Further, reduced UVB and low UV conditions resulted in higher concentrations of glucosinolate-derived nitriles. In conclusion, exposure to low doses of UVB and UV from the early to late developmental stages did not result in overall lower concentrations of plant secondary metabolites. KW - flavonoids KW - hydroxycinnamic acids KW - carotenoids KW - glucosinolates KW - nitriles KW - UVB reduction Y1 - 2018 U6 - https://doi.org/10.1021/acs.jafc.7b03996 SN - 0021-8561 SN - 1520-5118 VL - 66 IS - 7 SP - 1678 EP - 1692 PB - American Chemical Society CY - Washington ER - TY - JOUR A1 - Ribar, Anita A1 - Huber, Stefan E. A1 - Smialek, Malgorzata A. A1 - Tanzer, Katrin A1 - Neustetter, Michael A1 - Schürmann, Robin A1 - Bald, Ilko A1 - Denifl, Stephan T1 - Hydroperoxyl radical and formic acid formation from common DNA stabilizers upon low energy electron attachment JF - Physical chemistry, chemical physics : a journal of European Chemical Societies N2 - 2-Amino-2-(hydroxymethyl)-1,3-propanediol (TRIS) and ethylenediaminetetraacetic acid ( EDTA) are key components of biological buffers and are frequently used as DNA stabilizers in irradiation studies. Such surface or liquid phase studies are done with the aim to understand the fundamental mechanisms of DNA radiation damage and to improve cancer radiotherapy. When ionizing radiation is used, abundant secondary electrons are formed during the irradiation process, which are able to attach to the molecular compounds present on the surface. In the present study we experimentally investigate low energy electron attachment to TRIS and methyliminodiacetic acid ( MIDA), an analogue of EDTA, supported by quantum chemical calculations. The most prominent dissociation channel for TRIS is through hydroperoxyl radical formation, whereas the dissociation of MIDA results in the formation of formic and acetic acid. These compounds are well-known to cause DNA modifications, like strand breaks. The present results indicate that buffer compounds may not have an exclusive protecting effect on DNA as suggested previously. Y1 - 2018 U6 - https://doi.org/10.1039/c7cp07697e SN - 1463-9076 SN - 1463-9084 VL - 20 IS - 8 SP - 5578 EP - 5585 PB - Royal Society of Chemistry CY - Cambridge ER - TY - JOUR A1 - Schneider, Matthias A1 - Günter, Christina A1 - Taubert, Andreas T1 - Co-deposition of a hydrogel/calcium phosphate hybrid layer on 3D printed poly(lactic acid) scaffolds via dip coating BT - Towards Automated Biomaterials Fabrication JF - Polymers N2 - The article describes the surface modification of 3D printed poly(lactic acid) (PLA) scaffolds with calcium phosphate (CP)/gelatin and CP/chitosan hybrid coating layers. The presence of gelatin or chitosan significantly enhances CP co-deposition and adhesion of the mineral layer on the PLA scaffolds. The hydrogel/CP coating layers are fairly thick and the mineral is a mixture of brushite, octacalcium phosphate, and hydroxyapatite. Mineral formation is uniform throughout the printed architectures and all steps (printing, hydrogel deposition, and mineralization) are in principle amenable to automatization. Overall, the process reported here therefore has a high application potential for the controlled synthesis of biomimetic coatings on polymeric biomaterials. KW - 3D printing KW - dip-coating KW - poly(lactic acid) KW - PLA KW - calcium phosphate KW - gelatin KW - chitosan KW - hydrogel KW - calcium phosphate hybrid material KW - biomaterials Y1 - 2018 U6 - https://doi.org/10.3390/polym10030275 SN - 2073-4360 VL - 10 IS - 3 PB - MDPI CY - Basel ER - TY - JOUR A1 - Farhan, Muhammad A1 - Rudolph, Tobias A1 - Nöchel, Ulrich A1 - Kratz, Karl A1 - Lendlein, Andreas T1 - Extractable Free Polymer Chains Enhance Actuation Performance of Crystallizable Poly(epsilon-caprolactone) Networks and Enable Self-Healing JF - Polymers N2 - Crosslinking of thermoplastics is a versatile method to create crystallizable polymer networks, which are of high interest for shape-memory actuators. Here, crosslinked poly(epsilon-caprolactone) thermosets (cPCLs) were prepared from linear starting material, whereby the amount of extractable polymer was varied. Fractions of 5-60 wt % of non-crosslinked polymer chains, which freely interpenetrate the crosslinked network, were achieved leading to differences in the resulting phase of the bulk material. This can be described as "sponge-like" with open or closed compartments depending on the amount of interpenetrating polymer. The crosslinking density and the average network chain length remained in a similar range for all network structures, while the theoretical accessible volume for reptation of the free polymer content is affected. This feature could influence or introduce new functions into the material created by thermomechanical treatment. The effect of interpenetrating PCL in cPCLs on the reversible actuation was analyzed by cyclic, uniaxial tensile tests. Here, high reversible strains of up to Delta epsilon = 24% showed the enhanced actuation performance of networks with a non-crosslinked PCL content of 30 wt % resulting from the crystal formation in the phase of the non-crosslinked PCL and co-crystallization with network structures. Additional functionalities are reprogrammability and self-healing capabilities for networks with high contents of extractable polymer enabling reusability and providing durable actuator materials. KW - shape-memory polymer actuators KW - soft actuators KW - self-healing KW - poly(epsilon-caprolactone) KW - thermoplastics Y1 - 2018 U6 - https://doi.org/10.3390/polym10030255 SN - 2073-4360 VL - 10 IS - 3 PB - MDPI CY - Basel ER - TY - JOUR A1 - Behrendt, Felix Nicolas A1 - Schlaad, Helmut T1 - Entropy-Driven Ring-Opening Disulfide Metathesis Polymerization for the Synthesis of Functional Poly(disulfide)s JF - Macromolecular rapid communications N2 - Metal-free entropy-driven disulfide metathesis polymerization of unsaturated L-cystine based macrocycles produces high-molar-mass heterofunctional poly(disulfide)s, i.e., poly(ester-disulfide-alkene) and poly(amide-disulfide-alkene); M-w(app) = 44-60 kDa, (sic) > 1.7. The polymerization is fast and reaches equilibrium within 1-5 minutes (monomer conversion 70-90%) in polar aprotic solvents such as N,N-dimethylacetamide, dimethylsulfoxide, or y-valerolactone. Thiol-terminated polymers are stable in bulk or when dissolved in weakly polar solvents, but rapidly depolymerize in dilute polar solution. KW - disulfide KW - macrocycles KW - metathesis KW - ring-opening polymerization Y1 - 2018 U6 - https://doi.org/10.1002/marc.201700735 SN - 1022-1336 SN - 1521-3927 VL - 39 IS - 6 PB - Wiley-VCH CY - Weinheim ER - TY - JOUR A1 - Piluso, Susanna A1 - Vukicevie, Radovan A1 - Nöchel, Ulrich A1 - Braune, Steffen A1 - Lendlein, Andreas A1 - Neffe, Axel T. T1 - Sequential alkyne-azide cycloadditions for functionalized gelatin hydrogel formation JF - European polymer journal N2 - While click chemistry reactions for biopolymer network formation are attractive as the defined reactions may allow good control of the network formation and enable subsequent functionalization, tailoring of gelatin network properties over a wide range of mechanical properties has yet to be shown. Here, it is demonstrated that copper-catalyzed alkyne-azide cycloaddition of alkyne functionalized gelatin with diazides gave hydrogel networks with properties tailorable by the ratio of diazide to gelatin and diazide rigidity. 4,4′-diazido-2,2′-stilbenedisulfonic acid, which has been used as rigid crosslinker, yielded hydrogels with Young’s moduli E of 50–390 kPa and swelling degrees Q of 150–250 vol.%, while the more flexible 1,8-diazidooctane resulted in hydrogels with E = 125–280 kPa and Q = 225–470 vol.%. Storage moduli could be varied by two orders of magnitude (G′ = 100–20,000 Pa). An indirect cytotoxicity test did not show cytotoxic properties. Even when employing 1:1 ratios of alkyne and azide moieties, the hydrogels were shown to contain both, unreacted alkyne groups on the gelatin backbone as well as dangling chains carrying azide groups as shown by reaction with functionalized fluorescein. The free groups, which can be tailored by the employed ratio of the reactants, are accessible for covalent attachment of drugs, as was demonstrated by functionalization with dexamethasone. The sequential network formation and functionalization with click chemistry allows access to multifunctional materials relevant for medical applications. KW - Click chemistry KW - Hydrogel KW - Polymer functionalization KW - Biopolymer KW - Rheology KW - Multifunctionality Y1 - 2018 U6 - https://doi.org/10.1016/j.eurpolymj.2018.01.017 SN - 0014-3057 SN - 1873-1945 VL - 100 SP - 77 EP - 85 PB - Elsevier CY - Oxford ER - TY - JOUR A1 - Aravopoulou, Dionysia A1 - Kyriakos, Konstantinos A1 - Miasnikova, Anna A1 - Laschewsky, Andre A1 - Papadakis, Christine M. A1 - Kyritsis, Apostolos T1 - Comparative Investigation of the Thermoresponsive Behavior of Two Diblock Copolymers Comprising PNIPAM and PMDEGA Blocks JF - The journal of physical chemistry : B, Condensed matter, materials, surfaces, interfaces & biophysical chemistry N2 - The thermoresponsive behavior of two diblock copolymers PS-b-PNIPAM and PS-b-PMDEGA, which both comprise a hydrophobic polystyrene (PS) block but different thermoresponsive blocks, also differing in length, poly(N-isopropylacrylamide) (PNIPAM) and poly(methoxy diethylene glycol acrylate) (PMDEGA), respectively, was comparatively investigated in a wide temperature range. Concentrated aqueous solutions containing 25 wt % polymer were studied by small-angle X-ray scattering (SAXS), differential scanning calorimetry (DSC), and broadband dielectric spectroscopy (BDS). DSC measurements show that, during the demixing phase transition, the hydration number per oligo(ethylene glycol) side chain in the PS-b-PMDEGA solution decreases rather gradually, even up to 20 °C above the onset of the transition, i.e., the cloud point (CP). In contrast, the PS-b-PNIPAM solution exhibits an abrupt, stepwise dehydration behavior at its CP, indicated by the sharp, narrow endothermic peak. BDS measurements suggest that the organization of the expelled water during the phase transition and the subsequent evolution of the micellar aggregates are different for the two copolymers. In the PS-b-PMDEGA solution, the long-range charge transport process changes significantly at its CP and strong interfacial polarization processes appear, probably due to charge accumulation at the interfaces between the micellar aggregates and the aqueous medium. On the contrary, in the PS-b-PNIPAM solution, the phase transition has only a marginal effect on the long-range conduction process and is accompanied by a reduction in the high-frequency (1 MHz) dielectric permittivity, ε′. The latter effect is attributed to the reduced polarization strength of local chain modes due to an enhancement of intra- and interchain hydrogen bonds (HBs) in the polymer-rich phase during the water detaching process. Surprisingly, our BDS measurements indicate that prior to both the demixing and remixing processes the local chain mobility increases temporally. Our dielectric studies suggest that for PS-b-PNIPAM the water detaching process initiates a few degrees below CP and that the local chain mobility and intra- and/or interchain HBs of the PNIPAM blocks may control its thermoresponsive behavior. Dielectric “jump” experiments show that the kinetics of micellar aggregation in the PS-b-PMDEGA solution is slower than that in the PS-b-PNIPAM solution and is independent of the target temperature within the two-phase region. From the experimental point of view, it is shown that the dielectric susceptibility, especially, the dielectric permittivity, ε′, is a well-suited probe for monitoring both the reversible changes in the molecular dipolar bond polarizability and the long-range interfacial polarization at the phase transition. Y1 - 2018 U6 - https://doi.org/10.1021/acs.jpcb.7b09647 SN - 1520-6106 VL - 122 IS - 9 SP - 2655 EP - 2668 PB - American Chemical Society CY - Washington ER - TY - JOUR A1 - Schulze-Makuch, Dirk A1 - Wagner, Dirk A1 - Kounaves, Samuel P. A1 - Mangelsdorf, Kai A1 - Devine, Kevin G. A1 - de Vera, Jean-Pierre A1 - Schmitt-Kopplin, Philippe A1 - Grossart, Hans-Peter A1 - Parro, Victor A1 - Kaupenjohann, Martin A1 - Galy, Albert A1 - Schneider, Beate A1 - Airo, Alessandro A1 - Froesler, Jan A1 - Davila, Alfonso F. A1 - Arens, Felix L. A1 - Caceres, Luis A1 - Cornejo, Francisco Solis A1 - Carrizo, Daniel A1 - Dartnell, Lewis A1 - DiRuggiero, Jocelyne A1 - Flury, Markus A1 - Ganzert, Lars A1 - Gessner, Mark O. A1 - Grathwohl, Peter A1 - Guan, Lisa A1 - Heinz, Jacob A1 - Hess, Matthias A1 - Keppler, Frank A1 - Maus, Deborah A1 - McKay, Christopher P. A1 - Meckenstock, Rainer U. A1 - Montgomery, Wren A1 - Oberlin, Elizabeth A. A1 - Probst, Alexander J. A1 - Saenz, Johan S. A1 - Sattler, Tobias A1 - Schirmack, Janosch A1 - Sephton, Mark A. A1 - Schloter, Michael A1 - Uhl, Jenny A1 - Valenzuela, Bernardita A1 - Vestergaard, Gisle A1 - Woermer, Lars A1 - Zamorano, Pedro T1 - Transitory microbial habitat in the hyperarid Atacama Desert JF - Proceedings of the National Academy of Sciences of the United States of America KW - habitat KW - aridity KW - microbial activity KW - biomarker KW - Mars Y1 - 2018 U6 - https://doi.org/10.1073/pnas.1714341115 SN - 0027-8424 VL - 115 IS - 11 SP - 2670 EP - 2675 PB - National Acad. of Sciences CY - Washington ER - TY - GEN A1 - Mazzio, Katherine A. A1 - Thulasimani, Monika Raja A1 - Ryll, Britta A1 - Kojda, Sandrino Danny A1 - Habicht, Klaus A1 - Raoux, Simone T1 - Synthetic manipulation of hybrid thermoelectric materials T2 - Abstracts of papers : joint conference / The Chemical Institute of Cananda, CIC, American Chemical Society, ACS Y1 - 2018 SN - 0065-7727 VL - 255 PB - American Chemical Society CY - Washington ER - TY - JOUR A1 - Sarem, Melika A1 - Arya, Neha A1 - Heizmann, Miriam A1 - Neffe, Axel T. A1 - Barbero, Andrea A1 - Gebauer, Tim P. A1 - Martin, Ivan A1 - Lendlein, Andreas A1 - Shastri, V. Prasad T1 - Interplay between stiffness and degradation of architectured gelatin hydrogels leads to differential modulation of chondrogenesis in vitro and in vivo JF - Acta biomaterialia N2 - The limited capacity of cartilage to heal large lesions through endogenous mechanisms has led to extensive effort to develop materials to facilitate chondrogenesis. Although physical-chemical properties of biomaterials have been shown to impact in vitro chondrogenesis, whether these findings are translatable in vivo is subject of debate. Herein, architectured 3D hydrogel scaffolds (ArcGel) (produced by crosslinking gelatin with ethyl lysine diisocyanate (LDI)) were used as a model system to investigate the interplay between scaffold mechanical properties and degradation on matrix deposition by human articular chondrocytes (HAC) from healthy donors in vitro and in vivo. Using ArcGel scaffolds of different tensile and shear modulus, and degradation behavior; in this study, we compared the fate of ex vivo engineeredArcGels-chondrocytes constructs, i.e. the traditional tissue engineering approach, with the de novo formation of cartilaginous tissue in HAC laden ArcGels in an ectopic nude mouse model. While the softer and fast degrading ArcGel (LNCO3) was more efficient at promoting chondrogenic differentiation in vitro, upon ectopic implantation, the stiffer and slow degrading ArcGel (LNCO8) was superior in maintaining chondrogenic phenotype in HAC and retention of cartilaginous matrix. Furthermore, surprisingly the de novo formation of cartilage tissue was promoted only in LNCO8. Since HAC cultured for only three days in the LNCO8 environment showed upregulation of hypoxia-associated genes, this suggests a potential role for hypoxia in the observed in vivo outcomes. In summary, this study sheds light on how immediate environment (in vivo versus in vitro) can significantly impact the outcomes of cell-laden biomaterials. Statement of Significance In this study, 3D architectured hydrogels (ArcGels) with different mechanical and biodegradation properties were investigated for their potential to promote formation of cartilaginous matrix by human articular chondrocytes in vitro and in vivo. Two paradigms were explored (i) ex vivo engineering followed by in vivo implantation in ectopic site of nude mice and (ii) short in vitro culture (3 days) followed by implantation to induce de novo cartilage formation. Softer and fast degrading ArcGel were better at promoting chondrogenesis in vitro, while stiffer and slow degrading ArcGel were strikingly superior in both maintaining chondrogenesis in vivo and inducing de novo formation of cartilage. Our findings highlight the importance of the interplay between scaffold mechanics and degradation in chondrogenesis. KW - Cartilage repair KW - Scaffold stiffness KW - Scaffold contraction KW - Scaffold degradation KW - Matrix metalloproteinase KW - Hypoxia Y1 - 2018 U6 - https://doi.org/10.1016/j.actbio.2018.01.025 SN - 1742-7061 SN - 1878-7568 VL - 69 SP - 83 EP - 94 PB - Elsevier CY - Oxford ER - TY - JOUR A1 - Rackwitz, Jenny A1 - Bald, Ilko T1 - Low-energy electron-induced strand breaks in telomere-derived DNA sequences BT - influence of DNA sequence and topology JF - Chemistry - a European journal N2 - During cancer radiation therapy high-energy radiation is used to reduce tumour tissue. The irradiation produces a shower of secondary low-energy (<20 eV) electrons, which are able to damage DNA very efficiently by dissociative electron attachment. Recently, it was suggested that low-energy electron-induced DNA strand breaks strongly depend on the specific DNA sequence with a high sensitivity of G-rich sequences. Here, we use DNA origami platforms to expose G-rich telomere sequences to low-energy (8.8 eV) electrons to determine absolute cross sections for strand breakage and to study the influence of sequence modifications and topology of telomeric DNA on the strand breakage. We find that the telomeric DNA 5′-(TTA GGG)2 is more sensitive to low-energy electrons than an intermixed sequence 5′-(TGT GTG A)2 confirming the unique electronic properties resulting from G-stacking. With increasing length of the oligonucleotide (i.e., going from 5′-(GGG ATT)2 to 5′-(GGG ATT)4), both the variety of topology and the electron-induced strand break cross sections increase. Addition of K+ ions decreases the strand break cross section for all sequences that are able to fold G-quadruplexes or G-intermediates, whereas the strand break cross section for the intermixed sequence remains unchanged. These results indicate that telomeric DNA is rather sensitive towards low-energy electron-induced strand breakage suggesting significant telomere shortening that can also occur during cancer radiation therapy. KW - DNA damage KW - DNA strand breaks KW - low-energy electron KW - radiation therapy KW - telomeric DNA Y1 - 2018 U6 - https://doi.org/10.1002/chem.201705889 SN - 0947-6539 SN - 1521-3765 VL - 24 IS - 18 SP - 4680 EP - 4688 PB - Wiley-VCH CY - Weinheim ER - TY - JOUR A1 - Zimmermann, Marc A1 - John, Daniela A1 - Grigoriev, Dmitry A1 - Puretskiy, Nikolay A1 - Böker, Alexander T1 - From 2D to 3D patches on multifunctional particles BT - how microcontact printing creates a new dimension of functionality JF - Soft matter N2 - A straightforward approach for the precise multifunctional surface modification of particles with three-dimensional patches using microcontact printing is presented. By comparison to previous works it was possible to not only control the diameter, but also to finely tune the thickness of the deposited layer, opening up the way for three-dimensional structures and orthogonal multifunctionality. The use of PEI as polymeric ink, PDMS stamps for microcontact printing on silica particles and the influence of different solvents during particle release on the creation of functional particles with three-dimensional patches are described. Finally, by introducing fluorescent properties by incorporation of quantum dots into patches and by particle self-assembly via avidin-biotin coupling, the versatility of this novel modification method is demonstrated. Y1 - 2018 U6 - https://doi.org/10.1039/c8sm00163d SN - 1744-683X SN - 1744-6848 VL - 14 IS - 12 SP - 2301 EP - 2309 PB - Royal Society of Chemistry CY - Cambridge ER - TY - JOUR A1 - Heiden, Sophia A1 - Yue, Yanhua A1 - Kirsch, Harald A1 - Wirth, Jonas A. A1 - Saalfrank, Peter A1 - Campen, Richard Kramer T1 - Water dissociative adsorption on α-Al2O3(112̅0) is controlled by surface site undercoordination, density, and topology JF - The journal of physical chemistry / publ. weekly by the American Chemical Society : C, Nanomaterials and interfaces N2 - α-Al2O3 surfaces are common in a wide variety of applications and useful models of more complicated, environmentally abundant, alumino-silicate surfaces. While decades of work have clarified that all properties of these surfaces depend sensitively on the crystal face and the presence of even small amounts of water, quantitative insight into this dependence has proven challenging. Overcoming this challenge requires systematic study of the mechanism by which water interacts with various α-Al2O3 surfaces. Such insight is most easily gained for the interaction of small amounts of water with surfaces in ultra high vacuum. In this study, we continue our combined theoretical and experimental approach to this problem, previously applied to water interaction with the α-Al2O3 (0001) and (11̅02) surfaces, now to water interaction with the third most stable surface, that is, the (112̅0). Because we characterize all three surfaces using similar tools, it is straightforward to conclude that the (112̅0) is most reactive with water. The most important factor explaining its increased reactivity is that the high density of undercoordinated surface Al atoms on the (112̅0) surface allows the bidentate adsorption of OH fragments originating from dissociatively adsorbed water, while only monodentate adsorption is possible on the (0001) and (11̅02) surfaces: the reactivity of α-Al2O3 surfaces with water depends strongly, and nonlinearly, on the density of undercoordinated surface Al atoms. Y1 - 2018 U6 - https://doi.org/10.1021/acs.jpcc.7b10410 SN - 1932-7447 VL - 122 IS - 12 SP - 6573 EP - 6584 PB - American Chemical Society CY - Washington ER - TY - GEN A1 - Kochovski, Zdravko A1 - Jia, He A1 - Lu, Yan T1 - Morphological study of microgel-based colloidal systems by cryogenic transmission electron microscopy (cryo-TEM) T2 - Abstracts of papers : joint conference / The Chemical Institute of Cananda, CIC, American Chemical Society, ACS Y1 - 2018 SN - 0065-7727 VL - 256 PB - American Chemical Society CY - Washington ER - TY - JOUR A1 - Arias, Hugo R. A1 - Feuerbach, Dominik A1 - Schmidt, Bernd A1 - Heydenreich, Matthias A1 - Paz, Cristian A1 - Ortells, Marcelo O. T1 - Drimane Sesquiterpenoids Noncompetitively Inhibit Human alpha 4 beta 2 Nicotinic Acetylcholine Receptors with Higher Potency Compared to Human alpha 3 beta 4 and alpha 7 Subtypes JF - Journal of natural products N2 - The drimane sesquiterpenoids drimenin, cinnamolide, dendocarbin A, and polygodial were purified from the Canelo tree (Drimys winteri) and chemically characterized by spectroscopic methods. The pharmacological activity of these natural compounds were determined on hα4β2, hα3β4, and hα7 nicotinic acetylcholine receptors (AChRs) by Ca2+ influx measurements. The results established that drimane sesquiterpenoids inhibit AChRs with the following selectivity: hα4β2 > hα3β4 > hα7. In the case of hα4β2 AChRs, the following potency rank order was determined (IC50’s in μM): drimenin (0.97 ± 0.35) > cinnamolide (1.57 ± 0.36) > polygodial (62.5 ± 19.9) ≫ dendocarbin A (no activity). To determine putative structural features underlying the differences in inhibitory potency at hα4β2 AChRs, additional structure–activity relationship and molecular docking experiments were performed. The Ca2+ influx and structural results supported a noncompetitive mechanism of inhibition, where drimenin interacted with luminal and nonluminal (TMD-β2 intrasubunit) sites. The structure–activity relationship results, i.e., the lower the ligand polarity, the higher the inhibitory potency, supported the nonluminal interaction. Ligand binding to both sites might inhibit the hα4β2 AChR by a cooperative mechanism, as shown experimentally (nH > 1). Drimenin could be used as a molecular scaffold for the development of more potent inhibitors with higher selectivity for the hα4β2 AChR. Y1 - 2018 U6 - https://doi.org/10.1021/acs.jnatprod.7b00893 SN - 0163-3864 SN - 1520-6025 VL - 81 IS - 4 SP - 811 EP - 817 PB - American Chemical Society CY - Washington ER - TY - JOUR A1 - Muzdalo, Anja A1 - Saalfrank, Peter A1 - Vreede, Jocelyne A1 - Santer, Mark T1 - Cis-to-Trans Isomerization of Azobenzene Derivatives Studied with Transition Path Sampling and Quantum Mechanical/Molecular Mechanical Molecular Dynamics JF - Journal of chemical theory and computation N2 - Azobenzene-based molecular photoswitches are becoming increasingly important for the development of photoresponsive, functional soft-matter material systems. Upon illumination with light, fast interconversion between a more stable trans and a metastable cis configuration can be established resulting in pronounced changes in conformation, dipole moment or hydrophobicity. A rational design of functional photosensitive molecules with embedded azo moieties requires a thorough understanding of isomerization mechanisms and rates, especially the thermally activated relaxation. For small azo derivatives considered in the gas phase or simple solvents, Eyring’s classical transition state theory (TST) approach yields useful predictions for trends in activation energies or corresponding half-life times of the cis isomer. However, TST or improved theories cannot easily be applied when the azo moiety is part of a larger molecular complex or embedded into a heterogeneous environment, where a multitude of possible reaction pathways may exist. In these cases, only the sampling of an ensemble of dynamic reactive trajectories (transition path sampling, TPS) with explicit models of the environment may reveal the nature of the processes involved. In the present work we show how a TPS approach can conveniently be implemented for the phenomenon of relaxation–isomerization of azobenzenes starting with the simple examples of pure azobenzene and a push–pull derivative immersed in a polar (DMSO) and apolar (toluene) solvent. The latter are represented explicitly at a molecular mechanical (MM) and the azo moiety at a quantum mechanical (QM) level. We demonstrate for the push–pull azobenzene that path sampling in combination with the chosen QM/MM scheme produces the expected change in isomerization pathway from inversion to rotation in going from a low to a high permittivity (explicit) solvent model. We discuss the potential of the simulation procedure presented for comparative calculation of reaction rates and an improved understanding of activated states. Y1 - 2018 U6 - https://doi.org/10.1021/acs.jctc.7b01120 SN - 1549-9618 SN - 1549-9626 VL - 14 IS - 4 SP - 2042 EP - 2051 PB - American Chemical Society CY - Washington ER - TY - JOUR A1 - Liebig, Ferenc A1 - Sarhan, Radwan Mohamed A1 - Prietzel, Claudia Christina A1 - Schmitt, Clemens Nikolaus Zeno A1 - Bargheer, Matias A1 - Koetz, Joachim T1 - Tuned Surface-Enhanced raman scattering performance of undulated Au@Ag triangles JF - ACS applied nano materials N2 - Negatively charged ultraflat gold nanotriangles (AuNTs) stabilized by the anionic surfactant dioctyl sodium sulfosuccinate (AOT) were reloaded with the cationic surfactant benzylhexadecyldimethylammonium chloride (BDAC). Because of the spontaneous formation of a catanionic AOT micelle/BDAC bilayer onto the surface of the reloaded AuNTs, a reduction of Ag+ ions leads to the formation of spherical silver nanoparticles (AgNPs). With increasing concentration of AgNPs on the AuNTs, the localized surface plasmon resonance (LSPR) is shifted stepwise from 1300 to 800 nm. The tunable LSPR enables to shift the extinction maximum to the wavelength of the excitation laser of the Raman microscope at 785 nm. Surface-enhanced Raman scattering (SERS) experiments performed under resonance conditions show an SERS enhancement factor of the analyte molecule rhodamine RG6 of 5.1 X 10(5), which can be related to the silver hot spots at the periphery of the undulated gold nanoplatelets. KW - gold nanotriangles KW - catanionic surfactant bilayer KW - undulated nanoplatelets KW - SERS KW - LSPR Y1 - 2018 U6 - https://doi.org/10.1021/acsanm.8b00570 SN - 2574-0970 VL - 1 IS - 4 SP - 1995 EP - 2003 PB - American Chemical Society CY - Washington ER - TY - JOUR A1 - Guo, Ranran A1 - Tian, Ye A1 - Yang, Yueqi A1 - Jiang, Qin A1 - Wang, Yajun A1 - Yang, Wuli T1 - A Yolk-Shell nanoplatform for gene-silencing-enhanced photolytic ablation of cancer JF - Advanced functional materials N2 - Noninvasive near-infrared (NIR) light responsive therapy is a promising cancer treatment modality; however, some inherent drawbacks of conventional phototherapy heavily restrict its application in clinic. Rather than producing heat or reactive oxygen species in conventional NIR treatment, here a multifunctional yolk-shell nanoplatform is proposed that is able to generate microbubbles to destruct cancer cells upon NIR laser irradiation. Besides, the therapeutic effect is highly improved through the coalition of small interfering RNA (siRNA), which is codelivered by the nanoplatform. In vitro experiments demonstrate that siRNA significantly inhibits expression of protective proteins and reduces the tolerance of cancer cells to bubble-induced environmental damage. In this way, higher cytotoxicity is achieved by utilizing the yolk-shell nanoparticles than treated with the same nanoparticles missing siRNA under NIR laser irradiation. After surface modification with polyethylene glycol and transferrin, the yolk-shell nanoparticles can target tumors selectively, as demonstrated from the photoacoustic and ultrasonic imaging in vivo. The yolk-shell nanoplatform shows outstanding tumor regression with minimal side effects under NIR laser irradiation. Therefore, the multifunctional nanoparticles that combining bubble-induced mechanical effect with RNA interference are expected to be an effective NIR light responsive oncotherapy. KW - cancer KW - gene silencing KW - near-infrared absorption KW - photolytic ablation KW - yolk-shell nanoparticles Y1 - 2018 U6 - https://doi.org/10.1002/adfm.201706398 SN - 1616-301X SN - 1616-3028 VL - 28 IS - 14 PB - Wiley-VCH CY - Weinheim ER - TY - JOUR A1 - Vishnevetskaya, Natalya S. A1 - Hildebrand, Viet A1 - Dyakonova, Margarita A. A1 - Niebuur, Bart-Jan A1 - Kyriakos, Konstantinos A1 - Raftopoulos, Konstantinos N. A1 - Di, Zhenyu A1 - Müller-Buschbaum, Peter A1 - Laschewsky, Andre A1 - Papadakis, Christine M. T1 - Dual orthogonal switching of the "Schizophrenic" self-assembly of diblock copolymers JF - Macromolecules : a publication of the American Chemical Society N2 - Based on diblock copolymers, a pair of "schizophrenic" micellar systems is designed by combining a nonionic and thermoresponsive block with a zwitterionic block, which is thermoresponsive and salt-sensitive. The nonionic block is poly(N-isopropylacrylamide) (PNIPAM) or poly(N-isopropylmethacrylamide) (PNIPMAM) and exhibits a lower critical solution temperature (LCST) behavior in aqueous solution. The zwitterionic block is a polysulfobetaine, i.e., poly(4((3-methacrylamidopropyl)dimethylammonio)butane-1-sulfonate) (PSBP), and has an upper critical solution temperature (UCST) behavior with the clearing point decreasing with increasing salt concentration. The PSBP-b-PNIPAM and PSBP-b-PNIPMAM diblock copolymers are prepared by successive reversible addition-fragmentation chain transfer (RAFT) polymerizations. The PSBP block is chosen such that the clearing point of the homopolymer is significantly higher in pure water than the cloud point of PNIPAM or PNIPMAM. Using turbidimetry, H-1 NMR, and small-angle neutron scattering, we investigate the overall phase behavior as well as the structure and interaction between the micelles and the intermediate phase, both in salt-free D2O and in 0.004 M NaBr in D2O in a wide temperature range. We find that PSBP-b-PNIPAM at 50 g L-1 in salt-free D2O is turbid in the entire temperature range. It forms spherical micelles below the cloud point of PNIPAM and cylindrical micelles above. Similar behavior is observed for PSBP-b-PNIPMAM at 50 g L-1 in salt-free D2O with a slight and smooth increase of the light transmission below the cloud point of PNIPMAM and an abrupt decrease above. Upon addition of 0.004 M NaBr, the UCST-type cloud point of the PSBP-block is notably decreased, and an intermediate regime is encountered below the cloud point of PNIPMAM, where the light transmission is slightly enhanced. In this regime, the polymer solution exhibits behavior typical for polyelectrolyte solutions. Thus, double thermosensitive and salt-sensitive behavior with "schizophrenic" micelle formation is found, and the width of the intermediate regime, where both blocks are hydrophilic, can be tuned by the addition of electrolyte. Y1 - 2018 U6 - https://doi.org/10.1021/acs.macromol.8b00096 SN - 0024-9297 SN - 1520-5835 VL - 51 IS - 7 SP - 2604 EP - 2614 PB - American Chemical Society CY - Washington ER - TY - JOUR A1 - Kirpichenko, Svetlana A1 - Shainyan, Bagrat A. A1 - Kleinpeter, Erich A1 - Shlykov, Sergey A. A1 - Tran Dinh Phien, A1 - Albanov, Alexander T1 - Synthesis of 3-fluoro-3-methyl-3-silatetrahydropyran and its conformational preferences in gas and solution by GED, NMR and theoretical calculations JF - Tetrahedron N2 - The 3,3-disubstitued 3-silaheterocyclohexane with an electronegative substituent at silicon, 3-fluoro-3-methyl-3-silatetrahydropyran 1, was synthesized, and its molecular structure and conformational properties studied by gas-phase electron diffraction (GED) and low temperature C-13 and F-19 NMR spectroscopy. Quantum-chemical calculations were carried out both for the isolated species and Hcomplexes in gas and in polar medium. The predominance of the 1-FeqMeax conformer (1-F-eq:1-F-ax ratio of 65:35, Delta G degrees = 0.37 kcal/mol) determined from GED is close to the theoretically estimated conformational equilibrium, especially at the DFT level. In solution, low temperature NMR spectroscopy showed no decoalescence of the signals in C-13 (down to 95 K) and F-19 NMR spectra (down to 123 K). However, the calculated F-19 chemical shift of -173.6 ppm for the 1-FeqMeax conformer practically coincides with the experimentally observed value (-173 to -175 ppm) as distinct from that for the 1-FaxMeeq conformer (-188.8 ppm), suggesting compound 1 to be anancomeric in solution, in compliance with its theoretical and experimental preference in the gas phase. KW - 3-Fluoro-3-methyl-3-silatetrahydropyran KW - Conformational analysis KW - Gas phase electron diffraction KW - Low-temperature NMR KW - DFT KW - MP2 and CCSD(T) calculations Y1 - 2018 U6 - https://doi.org/10.1016/j.tet.2018.02.055 SN - 0040-4020 VL - 74 IS - 15 SP - 1859 EP - 1867 PB - Elsevier CY - Oxford ER - TY - JOUR A1 - Roder, Phillip A1 - Hille, Carsten T1 - Local tissue manipulation via a force- and pressure-controlled AFM micropipette for analysis of cellular processes JF - Scientific reports N2 - Local manipulation of complex tissues at the single-cell level is challenging and requires excellent sealing between the specimen and the micromanipulation device. Here, biological applications for a recently developed loading technique for a force-and pressure-controlled fluidic force microscope micropipette are described. This technique allows for the exact positioning and precise spatiotemporal control of liquid delivery. The feasibility of a local loading technique for tissue applications was investigated using two fluorescent dyes, with which local loading behaviour could be optically visualised. Thus, homogeneous intracellular distribution of CellTracker Red and accumulation of SYTO 9 Green within nuclei was realised in single cells of a tissue preparation. Subsequently, physiological micromanipulation experiments were performed. Salivary gland tissue was pre-incubated with the Ca2+-sensitive dye OGB-1. An intracellular Ca2+ rise was then initiated at the single-cell level by applying dopamine via micropipette. When pre-incubating tissue with the nitric oxide (NO)-sensitive dye DAF-FM, NO release and intercellular NO diffusion was observed after local application of the NO donor SNP. Finally, local micromanipulation of a well-defined area along irregularly shaped cell surfaces of complex biosystems was shown for the first time for the fluidic force microscope micropipette. Thus, this technique is a promising tool for the investigation of the spatiotemporal effects of locally applied substances in complex tissues. Y1 - 2018 U6 - https://doi.org/10.1038/s41598-018-24255-9 SN - 2045-2322 VL - 8 PB - Nature Publ. Group CY - London ER - TY - JOUR A1 - Liebig, Ferenc A1 - Sarhan, Radwan Mohamed A1 - Prietzel, Claudia Christina A1 - Thünemann, Andreas F. A1 - Bargheer, Matias A1 - Koetz, Joachim T1 - Undulated Gold Nanoplatelet Superstructures BT - In Situ Growth of Hemispherical Gold Nanoparticles onto the Surface of Gold Nanotriangles JF - Langmuir N2 - Negatively charged flat gold nanotriangles, formed in a vesicular template phase and separated by an AOT-micelle-based depletion flocculation, were reloaded by adding a cationic polyelectrolyte, that is, a hyperbranched polyethylenimine (PEI). Heating the system to 100 degrees C in the presence of a gold chloride solution, the reduction process leads to the formation of gold nanoparticles inside the polymer shell surrounding the nanoplatelets. The gold nanoparticle formation is investigated by UV-vis spectroscopy, small-angle X-ray scattering, and dynamic light scattering measurements in combination with transmission electron microscopy. Spontaneously formed gold clusters in the hyperbranched PEI shell with an absorption maximum at 350 nm grow on the surface of the nanotriangles as hemispherical particles with diameters of similar to 6 nm. High-resolution micrographs show that the hemispherical gold particles are crystallized onto the {111} facets on the bottom and top of the platelet as well as on the edges without a grain boundary. Undulated gold nanoplatelet superstructures with special properties become available, which show a significantly modified performance in SERS-detected photocatalysis regarding both reactivity and enhancement factor. Y1 - 2018 U6 - https://doi.org/10.1021/acs.langmuir.7b02898 SN - 0743-7463 VL - 34 IS - 15 SP - 4584 EP - 4594 PB - American Chemical Society CY - Washington ER - TY - JOUR A1 - Wessig, Pablo A1 - John, Leonard A1 - Mertens, Monique T1 - Extending the Class of [1,3]-Dioxolo[4.5-f]benzodioxole (DBD) Fluorescent Dyes JF - European journal of organic chemistry N2 - Synthetic routes to a collection of new fluorescent dyes are described, which are based on the [1,3]-dioxolo[4.5-f]benzodioxole (DBD) core. By introducing different electron withdrawing groups in 4- and 8-position of the DBD moiety the emission wavelength could be adjusted over a large spectral range from blue to orange light. KW - Functional organic materials KW - Fluorescence KW - DBD dyes KW - Large Stokes shifts KW - Aryllithium compounds KW - Heterocycles Y1 - 2018 U6 - https://doi.org/10.1002/ejoc.201800002 SN - 1434-193X SN - 1099-0690 VL - 2018 IS - 14 SP - 1674 EP - 1681 PB - Wiley-VCH CY - Weinheim ER - TY - JOUR A1 - Tian, Guang-Zong A1 - Hu, Jing A1 - Zhang, Heng-Xi A1 - Rademacher, Christoph A1 - Zou, Xiao-Peng A1 - Zheng, Hong-Ning A1 - Xu, Fei A1 - Wang, Xiao-Li A1 - Linker, Torsten A1 - Yin, Jian T1 - Synthesis and conformational analysis of linear homo- and heterooligomers from novel 2-C-branched sugar amino acids (SAAs) JF - Scientific reports N2 - Sugar amino acids (SAAs), as biologically interesting structures bearing both amino and carboxylic acid functional groups represent an important class of multifunctional building blocks. In this study, we develop an easy access to novel SAAs in only three steps starting from nitro compounds in high yields in analytically pure form, easily available by ceric (IV) mediated radical additions. Such novel SAAs have been applied in the assembly of total nine carbopeptoids with the form of linear homo-and heterooligomers for the structural investigations employing circular dichroism (CD) spectroscopy, which suggest that the carbopeptoids emerge a well-extended, left (or right)-handed conformation similar to polyproline II (PPII) helices. NMR studies also clearly demonstrated the presence of ordered secondary structural elements. 2D-ROESY spectra were acquired to identify i+1NH <-> (C1H)-C-i, (C2H)-C-i correlations which support the conformational analysis of tetramers by CD spectroscopy. These findings provide interesting information of SAAs and their oligomers as potential scaffolds for discovering new drugs and materials. Y1 - 2018 U6 - https://doi.org/10.1038/s41598-018-24927-6 SN - 2045-2322 VL - 8 PB - Nature Publ. Group CY - London ER - TY - JOUR A1 - John, Daniela A1 - Zimmermann, Marc A1 - Böker, Alexander T1 - Generation of 3-dimensional multi-patches on silica particles via printing with wrinkled stamps JF - Soft matter N2 - A simple route towards patchy particles with anisotropic patches with respect to a different functionality and directionality is presented. This method is based on microcontact printing of positively charged polyethylenimine (PEI) on silica particles using wrinkled stamps. Due to the wrinkled surface, the number of patches on the particles as well as the distance between two patches can be controlled. Y1 - 2018 U6 - https://doi.org/10.1039/c8sm00224j SN - 1744-683X SN - 1744-6848 VL - 14 IS - 16 SP - 3057 EP - 3062 PB - Royal Society of Chemistry CY - Cambridge ER - TY - JOUR A1 - Matic, Aleksandar A1 - Schlaad, Helmut T1 - Thiol-ene photofunctionalization of 1,4-polymyrcene JF - Polymer international N2 - 1,4-Polymyrcene was synthesized by anionic polymerization of -myrcene and was subjected to photochemical functionalization with various thiols (i.e. methyl thioglycolate, methyl 3-mercaptopropionate, butyl 3-mercaptopropionate, ethyl 2-mercaptopropionate and 2-methyl-2-propanethiol) using benzophenone/UV light as the radical source. The yield of thiol addition to the trisubstituted double bonds of 1,4-polymyrcene decreased in the order 1 degrees thiol (ca 95%) > 2 degrees thiol (ca 80%) > 3 degrees thiol (<5%), due to the reversibility of the thiol-ene reaction. Remarkably, thiol addition to the side-chain double bonds was 8 - 10 times (1 degrees thiol) or 24 times (2 degrees thiol) faster than to the main-chain double bonds, which can be explained by the different accessibility of the double bonds and steric hindrance. Despite the use of a 10-fold excess of thiol with respect to myrcene units, the thiol-ene addition was accompanied by chain coupling reactions, which in the extreme case of 3 degrees thiol (or in the absence of thiol) resulted in the formation of insoluble crosslinked material. As an example, a methyl-thioglycolate-functionalized 1,4-polymyrcene was saponified/crosslinked to give submicron polyelectrolyte particles in dilute alkaline solution. (c) 2018 Society of Chemical Industry KW - polymyrcene KW - thiol-ene KW - photochemistry KW - regioselectivity Y1 - 2018 U6 - https://doi.org/10.1002/pi.5534 SN - 0959-8103 SN - 1097-0126 VL - 67 IS - 5 SP - 500 EP - 505 PB - Wiley CY - Hoboken ER - TY - JOUR A1 - Paz, Cristian A1 - Heydenreich, Matthias A1 - Schmidt, Bernd A1 - Vadra, Nahir A1 - Baggio, Ricardo T1 - Three new dihydro-beta-agarofuran sesquiterpenes from the seeds of Maytenus boaria JF - Acta Crystallographica Section C N2 - As part of a project studying the secondary metabolites extracted from the Chilean flora, we report herein three new beta-agarofuran sesquiterpenes, namely (1S,4S,5S,6R,7R,8R,9R,10S)-6-acetoxy-4,9-dihydroxy-2,2,5a,9-tetramethyloctahydro-2H-3,9a-methanobenzo[b] oxepine-5,10-diylbis(furan-3-carboxylate), C27H32O11, (II), (1S,4S,5S,6R,7R,9S,10S)-6-acetoxy-9-hydroxy-2,2,5a, 9-tetramethyloctahydro-2H-3,9a-methanobenzo[ b] oxepine-5,10-diyl bis(furan-3-carboxylate), C27H32O10, (III), and (1S,4S,5S,6R,7R,9S,10S)-6-acetoxy-10-(benzoyloxy)-9-hydroxy-2,2,5a,9-tetramethyloctahydro-2H-3,9a-methanobenzo[b]oxepin-5-yl furan-3-carboxylate, C29H34O9, (IV), obtained from the seeds of Maytenus boaria and closely associated with a recently published relative [Paz et al. (2017). Acta Cryst. C73, 451-457]. In the (isomorphic) structures of (II) and (III), the central decalin system is esterified with an acetate group at site 1 and furoate groups at sites 6 and 9, and differ at site 8, with an OH group in (II) and no substituent in (III). This position is also unsubstituted in (IV), with site 6 being occupied by a benzoate group. The chirality of the skeletons is described as 1S, 4S, 5S, 6R, 7R, 8R, 9R, 10S in (II) and 1S, 4S, 5S, 6R, 7R, 9S, 10S in (III) and (IV), matching the chirality suggested by NMR studies. This difference in the chirality sequence among the title structures (in spite of the fact that the three skeletons are absolutely isostructural) is due to the differences in the environment of site 8, i.e. OH in (II) and H in (III) and (IV). This diversity in substitution, in turn, is responsible for the differences in the hydrogen-bonding schemes, which is discussed. KW - Celastraceae KW - Maytenus boaria KW - sesquiterpene KW - dihydro-beta-agarofuran KW - crystal structure KW - NMR KW - DSC Y1 - 2018 U6 - https://doi.org/10.1107/S2053229618005429 SN - 2053-2296 VL - 74 SP - 564 EP - 570 PB - International Union of Crystallography CY - Chester ER - TY - JOUR A1 - Starke, Ines A1 - Koch, Andreas A1 - Kammer, Stefan A1 - Holdt, Hans-Jürgen A1 - Möller, Heiko Michael T1 - Electrospray mass spectrometry and molecular modeling study of formation and stability of silver complexes with diazaperylene and bisisoquinoline JF - Journal of mass spectrometry N2 - The complex formation of the following diazaperylene ligands (L) 1,12-diazaperylene 1, 1,1-bisisoquinoline 2, 2,11-disubstituted 1,12-diazaperylenes (alkyl=methyl, ethyl, isopropyl, 3, 5, 7), 3,3-disubstituted 1,1-bisisoquinoline (alkyl=methyl, ethyl, isopropyl, 4, 6, 8 and with R=phenyl, 11 and with pyridine 12), and the 5,8-dimethoxy-substituted diazaperylene 9, 6,6-dimethoxy-substituted bisisoquinoline 10 with AgBF4 was investigated. Collision-induced dissociation measurements were used to evaluate the relative stabilities of the ligands themselves and for the [1:1](+) complexes as well as for the homoleptic and heteroleptic silver [1:2](+) complexes in the gas phase. This method is very useful in rapid screening of the stabilities of new complexes in the gas phase. The influence of the spatial arrangement of the ligands and the type of substituents employed for the complexation were examined. The effect of the preorganization of the diazaperylene on the threshold activation voltages and thus of the relative binding energies of the different complexes are discussed. Density functional theory calculations were used to calculate the optimized structures of the silver complexes and compared with the stabilities of the complexes in the gas phase for the first time. KW - electrospray ionization mass spectrometry and modeling KW - silver(1) complexes KW - stability Y1 - 2018 U6 - https://doi.org/10.1002/jms.4071 SN - 1076-5174 SN - 1096-9888 VL - 53 IS - 5 SP - 408 EP - 418 PB - Wiley CY - Hoboken ER - TY - JOUR A1 - Bouakline, Foudhil T1 - Unambiguous signature of the berry phase in intense laser dissociation of diatomic molecules JF - The journal of physical chemistry letters N2 - We report strong evidence of Berry phase effects in intense laser dissociation of D-2(+) molecules, manifested as Aharonov-Bohm-like oscillations in the photofragment angular distribution (PAD). Our calculations show that this interference pattern strongly depends on the parity of the diatom initial rotational state, (-1)(j). Indeed, the PAD local maxima (minima) observed in one case (j odd) correspond to local minima (maxima) in the other case (j even). Using simple topological arguments, we clearly show that such interference conversion is a direct signature of the Berry phase. The sole effect of the latter on the rovibrational wave function is a sign change of the relative phase between two interfering components, which wind in opposite senses around a light-induced conical intersection (LICI). Therefore, encirclement of the LICI leads to constructive (j odd) or destructive (j even) self-interference of the initial nuclear wavepacket in the dissociative limit. To corroborate our theoretical findings, we suggest an experiment of strong-field indirect dissociation of D-2(+) molecules, comparing the PAD of the ortho and para molecular species in directions nearly perpendicular to the laser polarization axis. Y1 - 2018 U6 - https://doi.org/10.1021/acs.jpclett.8b00607 SN - 1948-7185 VL - 9 IS - 9 SP - 2271 EP - 2277 PB - American Chemical Society CY - Washington ER -