TY - JOUR A1 - Cortez, Nicole A1 - Marin, Victor A1 - Jimenez, Veronica A. A1 - Silva, Victor A1 - Leyton, Oscar A1 - Cabrera-Pardo, Jaime R. A1 - Schmidt, Bernd A1 - Heydenreich, Matthias A1 - Burgos, Viviana A1 - Duran, Paola A1 - Paz, Cristian T1 - Drimane sesquiterpene alcohols with activity against Candida yeast obtained by biotransformation with Cladosporium antarcticum JF - International journal of molecular sciences N2 - Fungal biotransformation is an attractive synthetic strategy to produce highly specific compounds with chemical functionality in regions of the carbon skeleton that are not easily activated by conventional organic chemistry methods. In this work, Cladosporium antarcticum isolated from sediments of Glacier Collins in Antarctica was used to obtain novel drimane sesquiterpenoids alcohols with activity against Candida yeast from drimendiol and epidrimendiol. These compounds were produced by the high-yield reduction of polygodial and isotadeonal with NaBH4 in methanol. Cladosporium antarcticum produced two major products from drimendiol, identified as 9 alpha-hydroxydrimendiol (1, 41.4 mg, 19.4% yield) and 3 beta-hydroxydrimendiol (2, 74.8 mg, 35% yield), whereas the biotransformation of epidrimendiol yielded only one product, 9 beta-hydroxyepidrimendiol (3, 86.6 mg, 41.6% yield). The products were purified by column chromatography and their structure elucidated by NMR and MS. The antifungal activity of compounds 1-3 was analyzed against Candida albicans, C. krusei and C. parapsilosis, showing that compound 2 has a MIC lower than 15 mu g/mL against the three-pathogenic yeast. In silico studies suggest that a possible mechanism of action for the novel compounds is the inhibition of the enzyme lanosterol 14 alpha-demethylase, affecting the ergosterol synthesis. KW - Drimys winteri KW - Cladosporium antarcticum KW - drimendiol KW - epidrimendiol KW - biotransformation KW - Candida yeast KW - lanosterol 14 alpha-demethylase KW - biocontrol Y1 - 2022 U6 - https://doi.org/10.3390/ijms232112995 SN - 1422-0067 VL - 23 IS - 21 PB - MDPI CY - Basel ER - TY - JOUR A1 - Marin, Victor A1 - Bart, Bryan A1 - Cortez, Nicole A1 - Jiménez, Verónica A. A1 - Silva, Victor A1 - Leyton, Oscar A1 - Cabrera-Pardo, Jaime R. A1 - Schmidt, Bernd A1 - Heydenreich, Matthias A1 - Burgos, Viviana A1 - Paz, Cristian T1 - Drimane sesquiterpene aldehydes control Candida yeast isolated from candidemia in Chilean patients JF - International journal of molecular sciences N2 - Drimys winteri J.R. (Winteraceae) produce drimane sesquiterpenoids with activity against Candida yeast. In this work, drimenol, polygodial (1), isotadeonal (2), and a new drimane alpha,beta-unsaturated 1,4-dialdehyde, named winterdial (4), were purified from barks of D. winteri. The oxidation of drimenol produced the monoaldehyde drimenal (3). These four aldehyde sesquiterpenoids were evaluated against six Candida species isolated from candidemia patients in Chilean hospitals. Results showed that 1 displays fungistatic activity against all yeasts (3.75 to 15.0 mu g/mL), but irritant effects on eyes and skin, whereas its non-pungent epimer 2 has fungistatic and fungicide activities at 1.9 and 15.0 mu g/mL, respectively. On the other hand, compounds 3 and 4 were less active. Molecular dynamics simulations suggested that compounds 1-4 are capable of binding to the catalytic pocket of lanosterol 14-alpha demethylase with similar binding free energies, thus suggesting a potential mechanism of action through the inhibition of ergosterol synthesis. According to our findings, compound 2 appears as a valuable molecular scaffold to pursue the future development of more potent drugs against candidiasis with fewer side effects than polygodial. These outcomes are significant to broaden the alternatives to treat fungal infections with increasing prevalence worldwide using natural compounds as a primary source for active compounds. KW - drimane sesquiterpenoids KW - Drimys winteri KW - isotadeonal KW - winterdial KW - Candida yeast KW - lanosterol 14-α-demethylase KW - molecular dynamics Y1 - 2022 U6 - https://doi.org/10.3390/ijms231911753 SN - 1422-0067 VL - 23 IS - 19 PB - Molecular Diversity Preservation International CY - Basel ER - TY - JOUR A1 - Schürmann, Robin A1 - Dutta, Anushree A1 - Ebel, Kenny A1 - Tapio, Kosti A1 - Milosavljevic, Aleksander R. A1 - Bald, Ilko T1 - Plasmonic reactivity of halogen thiophenols on gold nanoparticles studied by SERS and XPS JF - The journal of chemical physics : bridges a gap between journals of physics and journals of chemistr N2 - Localized surface plasmon resonances on noble metal nanoparticles (NPs) can efficiently drive reactions of adsorbed ligand molecules and provide versatile opportunities in chemical synthesis. The driving forces of these reactions are typically elevated temperatures, hot charge carriers, or enhanced electric fields. In the present work, dehalogenation of halogenated thiophenols on the surface of AuNPs has been studied by surface enhanced Raman scattering (SERS) as a function of the photon energy to track the kinetics and identify reaction products. Reaction rates are found to be surprisingly similar for different halothiophenols studied here, although the bond dissociation energies of the C-X bonds differ significantly. Complementary information about the electronic properties at the AuNP surface, namely, work-function and valence band states, has been determined by x-ray photoelectron spectroscopy of isolated AuNPs in the gas-phase. In this way, it is revealed how the electronic properties are altered by the adsorption of the ligand molecules, and we conclude that the reaction rates are mainly determined by the plasmonic properties of the AuNPs. SERS spectra reveal differences in the reaction product formation for different halogen species, and, on this basis, the possible reaction mechanisms are discussed to approach an understanding of opportunities and limitations in the design of catalytical systems with plasmonic NPs. Y1 - 2022 U6 - https://doi.org/10.1063/5.0098110 SN - 0021-9606 SN - 1089-7690 VL - 157 IS - 8 PB - American Institute of Physics CY - Melville, NY ER - TY - JOUR A1 - Braune, S. A1 - Baeckemo, J. A1 - Lau, S. A1 - Heuchel, M. A1 - Kratz, K. A1 - Jung, F. A1 - Reinthaler, M. A1 - Lendlein, Andreas T1 - The influence of different rewetting procedures on the thrombogenicity of nanoporous poly(ether imide) microparticles JF - Clinical hemorheology and microcirculation : blood flow and vessels N2 - Nanoporous microparticles prepared from poly(ether imide) (PEI) are discussed as candidate adsorber materials for the removal of uremic toxins during apheresis. Polymers exhibiting such porosity can induce the formation of micro-gas/air pockets when exposed to fluids. Such air presenting material surfaces are reported to induce platelet activation and thrombus formation. Physical or chemical treatments prior to implantation are discussed to reduce the formation of such gas nuclei. Here, we report about the influence of different rewetting procedures - as chemical treatments with solvents on the thrombogenicity of hydrophobic PEI microparticles and PEI microparticles hydrophilized by covalent attachment of poly(vinyl pyrrolidone) (PVP) of two different chain lengths.
Autoclaved dry PEI particles of all types with a diameter range of 200 - 250 mu m and a porosity of about 84%+/- 2% were either rewetted directly with phosphate buffered saline (24 h) or after immersion in an ethanol-series. Thrombogenicity of the particles was studied in vitro upon contact with human sodium citrated whole blood for 60 min at 5 rpm vertical rotation. Numbers of non-adherent platelets were quantified, and adhesion of blood cells was qualitatively analyzed by bright field microscopy. Platelet activation (percentage of CD62P positive platelets and amounts of soluble P-Selectin) and platelet function (PFA100 closure times) were analysed.
Retention of blood platelets on the particles was similar for all particle types and both rewetting procedures. Non-adherent platelets were less activated after contact with ethanol-treated particles of all types compared to those rewetted with phosphate buffered saline as assessed by a reduced number of CD62P-positive platelets and reduced amounts of secreted P-Selectin (P < 0.05 each). Interestingly, the hydrophilic surfaces significantly increased the number of activated platelets compared to hydrophobic PEI regardless of the rewetting agent. This suggests that, apart from wettability, other material properties might be more important to regulate platelet activation. PFA100 closure times were reduced and within the reference ranges in the ethanol group, however, significantly increased in the saline group. No substantial difference was detected between the tested surface modifications. In summary, rewetting with ethanol resulted in a reduced thrombogenicity of all studied microparticles regardless of their wettability, most likely resulting from the evacuation of air from the nanoporous particles. KW - biomaterial KW - polymer KW - microparticle KW - thrombogenicity KW - hemocompatibility KW - dynamic in-vitro test KW - rewetting Y1 - 2021 U6 - https://doi.org/10.3233/CH-201029 SN - 1386-0291 SN - 1875-8622 VL - 77 IS - 4 SP - 367 EP - 380 PB - IOS Press CY - Amsterdam ER - TY - JOUR A1 - Farrokhzadeh, Abdolkarim A1 - Modarresi-Alam, Ali Reza A1 - Akher, Farideh Badichi A1 - Kleinpeter, Erich A1 - Kelling, Alexandra A1 - Schilde, Uwe T1 - Investigation of the unusually high rotational energy barrier about the C-N bond in 5-(2-x-phenyl)-N,N-dimethyl-2H-tetrazole-2-carboxamides BT - insights from dynamic H-1-NMR and DFT calculations JF - Journal of molecular structure N2 - In this study, the synthesis of new 5 (2-x-phenyl)-N,N-dimethyl-2H-tetrazole-2-carboxamides (X = H and Cl) is reported coupled with the investigation of their dynamic H-1-NMR via rotation about C-N bonds in the moiety of urea group [a; CO-NMe2] in DMSO solvent (298-373 K). Accordingly, activation free energies of 17.32 and 17.50 kcal mol(-1) were obtained for X = H and Cl respectively, with respect to the conformational isomerization about the Me2N-C=O bond (a rotation). Moreover, a and b [b; 2-tetrazolyl-CO rotations] barrier to rotations in 5-(2-x-phenyl)-N,N-dimethyl-2H-tetrazole-2-carboxamides were also calculated by B3LYP/6-311++G** procedure. The optimized geometry parameters are well consistent with the X-ray data. Computed rotational energy barriers (X = Cl) for a and b were estimated to be 17.52 and 2.53 kcal mol(-1), respectively, the former in agreement with the dynamic NMR results. X-ray structures verify that just 2-acylated tetrazoles are formed in the case of 5-(2-x-phenyl)-N,N-dimethyl-2H-tetrazole-2-carboxamides. A planar trigonal orientation of the Me2N group was proven by X-ray data, which is coplanar to the carbonyl group, coupled with partial double bond C-N character. This also illustrates the syn-periplanar position of the tetrazolyl ring with C=O group. In solution, the planes containing tetrazolyl ring and the carbonyl bond are almost perpendicular to each other (because of steric effects as confirmed by calculations) while the planes containing carbonyl bond and Me2N group are coplanar. This phenomenon is in contrast with similar urea derivatives and explains the reason for the unusually high rotational energy barrier of these compounds. (C) 2020 Elsevier B.V. All rights reserved. KW - carbamoyl tetrazoles KW - barrier to rotation about C-N bond KW - dynamic KW - H-1-NMR KW - quantum mechanical calculations KW - X-ray structures Y1 - 2020 U6 - https://doi.org/10.1016/j.molstruc.2020.129363 SN - 0022-2860 SN - 1872-8014 VL - 1226 IS - Part B PB - Elsevier CY - New York, NY ER - TY - JOUR A1 - Stojanović, Ivan A1 - Židov, Bruno A1 - Travkova, Oksana A1 - Grigoriev, Dmitry T1 - Enhanced protective performance of waterborne, microcontainers-doped coatings in harsh environments JF - Progress in organic coatings : an international journal N2 - In this study, the corrosion inhibitors Zinc oleate and 8-Hydroxyquinoline were successfully encapsulated using an interfacial polyaddition method. As such they were dispersed at different concentrations within the waterborne coating matrix. The resulting composite coatings were applied to the low carbon steel substrates. Successful synthesis and morphological characteristics of microcontainers loaded with inhibitors were confirmed using various characterization techniques. Scanning electron microscopy, dynamic light scattering, and thermogravimetric measurements are techniques used to define the surface, dimensional, and dispersive characteristics of containers, and the share of encapsulated inhibitors. The release study defined the discharge kinetics of the corrosion inhibitor from the microcontainers dispersed freely in an aqueous medium. Electrochemical impedance spectroscopy was used to determine the anticorrosive performance of the samples continuously exposed to various corrosive environments of salt and humidity chambers and NaCl solution. Special emphasis was placed on adhesion testing and visual observations during the exposure period. Significant improvements have been noted in terms of corrosion resistance, which, however, depend on the type of inhibitor used, the concentration of the containers embedded in the coating matrix and on the characteristics of the corrosive environment. KW - Self-protecting coatings KW - Interfacial polyaddition KW - Inhibitor loaded KW - microcontainers KW - Corrosion inhibitors Y1 - 2021 U6 - https://doi.org/10.1016/j.porgcoat.2021.106273 SN - 0300-9440 SN - 1873-331X VL - 157 PB - Elsevier Science CY - Amsterdam [u.a.] ER - TY - JOUR A1 - Gahlaut, Shashank K. A1 - Pathak, Anisha A1 - Gupta, Banshi D. T1 - Recent advances in silver nanostructured substrates for plasmonic sensors JF - Biosensors : open access journal N2 - Noble metal nanostructures are known to confine photon energies to their dimensions with resonant oscillations of their conduction electrons, leading to the ultrahigh enhancement of electromagnetic fields in numerous spectroscopic methods. Of all the possible plasmonic nanomaterials, silver offers the most intriguing properties, such as best field enhancements and tunable resonances in visible-to-near infrared regions. This review highlights the recent developments in silver nanostructured substrates for plasmonic sensing with the main emphasis on surface plasmon resonance (SPR) and surface-enhanced Raman spectroscopy (SERS) over the past decade. The main focus is on the synthesis of silver nanostructured substrates via physical vapor deposition and chemical synthesis routes and their applications in each sensing regime. A comprehensive review of recent literature on various possible silver nanostructures prepared through these methodologies is discussed and critically reviewed for various planar and optical fiber-based substrates. KW - silver KW - plasmonics KW - sensors KW - surface-enhanced Raman spectroscopy KW - surface-enhanced fluorescence KW - surface-enhanced infrared spectroscopy Y1 - 2022 U6 - https://doi.org/10.3390/bios12090713 SN - 2079-6374 VL - 12 IS - 9 PB - MDPI CY - Basel ER - TY - JOUR A1 - Diehn, Sabrina Maria A1 - Schlaad, Helmut A1 - Kneipp, Janina T1 - Multivariate imaging for fast evaluation of in situ dark field microscopy hyperspectral data JF - Molecules : a journal of synthetic chemistry and natural product chemistry N2 - Dark field scattering microscopy can create large hyperspectral data sets that contain a wealth of information on the properties and the molecular environment of noble metal nanoparticles. For a quick screening of samples of microscopic dimensions that contain many different types of plasmonic nanostructures, we propose a multivariate analysis of data sets of thousands to several hundreds of thousands of scattering spectra. By using non-negative matrix factorization for decomposing the spectra, components are identified that represent individual plasmon resonances and relative contributions of these resonances to particular microscopic focal volumes in the mapping data sets. Using data from silver and gold nanoparticles in the presence of different molecules, including gold nanoparticle-protein agglomerates or silver nanoparticles forming aggregates in the presence of acrylamide, plasmonic properties are observed that differ from those of the original nanoparticles. For the case of acrylamide, we show that the plasmon resonances of the silver nanoparticles are ideally suited to support surface enhanced Raman scattering (SERS) and the two-photon excited process of surface enhanced hyper Raman scattering (SEHRS). Both vibrational tools give complementary information on the in situ formed polyacrylamide and the molecular composition at the nanoparticle surface. KW - localized surface plasmon resonances KW - gold nanoparticles KW - silver nanoparticles KW - dark field microscopy KW - acrylamide KW - hyperspectral imaging KW - non-negative matrix factorization KW - surface-enhanced Raman scattering (SERS) KW - surface-enhanced hyper Raman scattering (SEHRS) Y1 - 2022 U6 - https://doi.org/10.3390/molecules27165146 SN - 1420-3049 VL - 27 IS - 16 PB - MDPI CY - Basel ER - TY - JOUR A1 - Tarazona, Natalia A. A1 - Wei, Ren A1 - Brott, Stefan A1 - Pfaff, Lara A1 - Bornscheuer, Uwe T. A1 - Lendlein, Andreas A1 - Machatschek, Rainhard T1 - Rapid depolymerization of poly(ethylene terephthalate) thin films by a dual-enzyme system and its impact on material properties JF - Chem Catalysis N2 - Enzymatic hydrolysis holds great promise for plastic waste recycling and upcycling. The interfacial catalysis mode, and the variability of polymer specimen properties under different degradation conditions, add to the complexity and difficulty of understanding polymer cleavage and engineering better biocatalysts. We present a systemic approach to studying the enzyme-catalyzed surface erosion of poly(ethylene terephthalate) (PET) while monitoring/controlling operating conditions in real time with simultaneous detection of mass loss and changes in viscoelastic behavior. PET nanofilms placed on water showed a porous morphology and a thicknessdependent glass transition temperature (T-g) between 40 degrees C and 44 degrees C, which is >20 degrees C lower than the T-g of bulk amorphous PET. Hydrolysis by a dual-enzyme system containing thermostabilized variants of Ideonella sakaiensis PETase and MHETase resulted in a maximum depolymerization of 70% in 1 h at 50 degrees C. We demonstrate that increased accessible surface area, amorphization, and T-g reduction speed up PET degradation while simultaneously lowering the threshold for degradation-induced crystallization. Y1 - 2022 U6 - https://doi.org/10.1016/j.checat.2022.11.004 SN - 2667-1093 SN - 2667-1107 VL - 2 IS - 12 SP - 3573 EP - 3589 PB - Cell Press CY - Cambridge ER - TY - JOUR A1 - Rothe, Martin A1 - Zhao, Yuhang A1 - Halim, Henry A1 - Lu, Yan A1 - Benson, Oliver T1 - Spatial mapping of bleaching in a metal-organic plasmon converter JF - Optics continuum N2 - Hybrid nanophotonic elements, fabricated by organic and inorganic materials, are going to be key components of modern devices. Coupled systems of photoemitters with a plasmonic waveguide serve the demand for nanoscopic frequency converters. However, processes like the degradation of the photoemitters via photobleaching occur and need to be monitored and controlled, to realize future successful devices. We introduce a hybrid perylene-diimide / silver nanowire as plasmon frequency converter. A versatile method is presented to monitor and analyze the bleaching process. It is based on a time series of photoluminescence images, during the operation of a single converter. An analytical model is applied on the data and unveils that the photobleaching rate is constant and independent of the operation of the plasmon converter. Y1 - 2022 U6 - https://doi.org/10.1364/OPTCON.454911 SN - 2770-0208 VL - 1 IS - 8 SP - 1730 EP - 1740 PB - Optica Publishing Group CY - Washington ER -