New N-acylated aminoalkanoic acids from tea roots derived biocontrol agent Clonostachys rosea 15020.

Four new N-acylated aminoalkanoic acids, namely clonoroseins E-H (1-4), together with three previously identified analogs, clonoroseins A, B, and D (5-7), were identified from the endophytic fungus Clonostachys rosea strain 15020 (CR15020), using Feature-based Molecular Networking (FBMN). The elucidation of their chemical structures, including their absolute configurations, was achieved through spectroscopic analysis combined with quantum chemical calculations. Bioinformatics analyses suggested that an iterative type I HR-PKS (CrsE) generates the polyketide side chain of these clonoroseins. Furthermore, a downstream adenylate-forming enzyme of the PKS (CrsD) was suspected to function as an amide synthetase. CrsD potentially facilitates the transformation of the polyketide moiety into an acyl-AMP intermediate, followed by nucleophilic substitution with either ß-alanine or γ-aminobutyric acid to produce amide derivatives. These findings significantly expand our understanding of PKS-related products originating from C. rosea and also underscore the powerful application of FBMN analytical methods in characterization of new compounds.

Emulsion Assembly of Graphene Oxide/Polymer Composite Membranes.

Graphene oxide/polymer composite water filtration membranes were developed via coalescence of graphene oxide (GO) stabilized Pickering emulsions around a porosity-generating polymer. Triptycene poly(ether ether sulfone)-CH2NH2:HCl polymer interacts with the GO at the water-oil interface, resulting in stable Pickering emulsions. When they are deposited and dried on polytetrafluoroethylene substrate, the emulsions fuse to form a continuous GO/polymer composite membrane. X-ray diffraction and scanning electron microscopy demonstrate that the intersheet spacing and thickness of the membranes increased with increasing polymer concentration, confirming the polymer as the spacer between the GO sheets. The water filtration capability of the composite membranes was tested by removing Rose Bengal from water, mimicking separations of weak black liquor waste. The composite membrane achieved 65% rejection and 2500 g m-2 h-1 bar-1. With high polymer and GO loading, composite membranes give superior rejection and permeance performance when compared with a GO membrane. This methodology for fabrication membranes via GO/polymer Pickering emulsions produces membranes with a homogeneous morphology and robust chemical separation strength.

Chemiresistive Hydrogen Sensing with Size-Limited Palladium Nanoparticles in Iptycene-Containing Poly(arylene ether)s.

Metal nanoparticles have been widely employed in chemical sensing due to their high reactivity toward various gases. The size of the metal nanoparticles often dictates their reactivity and hence their performance as chemiresistive sensors. Herein, we report that iptycene-containing poly(arylene ether)s (PAEs) have been shown to limit the growth of palladium nanoparticles (Pd NPs) and stabilize the Pd NPs dispersion. These porous PAEs also facilitate the efficient transport of analytes. Single-walled carbon nanotube (SWCNT)-based chemiresistors and graphene field-effect transistors (GFETs) using these PAE-supported small Pd NPs are sensitive, selective, and robust sensory materials for hydrogen gas under ambient conditions. Generalizable strategies including presorting SWCNTs with pentiptycene-containing poly(p-phenylene ethynylene)s (PPEs) and thermal annealing demonstrated significant improvements in the chemiresistive performance. The polymer:NP colloids produced in this study are readily synthesized and solution processable, and these methods are of general utility.

Cyclodextrin-Functionalized Polypyrrole Particles for the Extraction of Aromatics from Water.

We describe the preparation of oil-in-water (o/w) colloidal particles with a polypyrrole (pPy) shell in which cyclodextrin has been incorporated at the oil-water interface via either physical adsorption or reaction with the pPy shell. The utility of these particles was assessed by the extraction of organic dyes from water. In all cases, we found that cyclodextrin incorporation significantly improved dye uptake, giving up to 78 ± 11% dye extraction in the case of a 100 ppm solution of 4-nitroaniline with a covalently incorporated cyclodextrin. We demonstrated the ability of our colloidal particles to extract nicotine-derived nitrosamine ketone (NNK), a potent carcinogen, from aqueous solution. By treating the solution containing 100 ppm NNK with our particles over 24 and 48 h, we found that NNK removal reached 65 ± 2 and 83 ± 1%, respectively. The uptake could be improved by re-treating a solution with additional freshly prepared particles, to achieve 95 ± 1% NNK extraction with a covalently incorporated cyclodextrin.

Wireless Lateral Flow Device for Biosensing.

Many biosensing methods rely on signals produced by enzyme-catalyzed reactions and efficient methods to detect and record this activity. Herein, we report a wireless lateral flow device and demonstrate the conversion of oxidase reactions to changes in the resonance of radio frequency identification (RFID) circuits. The detection is triggered by polyoxometalate-catalyzed oxidative doping of polypyrrole (pPy) when exposed to oxidase-generated H2O2. We have integrated this transduction and RFID capability into a lateral flow device to create a low-cost, rapid, and portable method for quantitative biological signal detection. We further report a new method for creating functional coatings from pPy core-shell colloidal particles bioconjugated for streptavidin-biotin recognition with glucose oxidase or pyruvate oxidase. The biofunctionalized pPy particles coalesce on the nitrocellulose membrane to produce a chemiresistive band. Glucose or pyruvate solutions result in formation of H2O2 at the pPy bands, functionalized with the respective oxidase, to produce conductivity enhancements exceeding 7·105%. Placing the pPy band in the RFID circuit converts the resistivity response to a change of RF resonance. The enzymatic response of glucose oxidase is recorded within 30 min with as low as 0.6 mM of glucose using this lateral flow device. Pyruvate is also shown to produce large responses. The oxidase enzymes/pPy transduction establishes a resistivity-based platform for the construction of a new family of lateral flow devices capable of detecting and quantifying biological targets.

Porous Polymers Containing Metallocalix[4]arene for the Extraction of Tobacco-Specific Nitrosamines.

We designed porous polymers with a tungsten-calix[4]arene imido complex as the nitrosamine receptor for the efficient extraction of tobacco-specific nitrosamines (TSNAs) from water. The interaction between the metallocalix[4]arene and the TSNA, 4-(methylnitrosamino)-1-(3-pyridyl)-1-butanone (nicotine-derived nitrosamine ketone, NNK) was investigated. We found that the incorporation of the nitrosamine receptor into porous polymers increased their selectivity toward NNK over nicotine. The polymer with an optimal ratio of calixarene-containing and porosity-inducing building blocks showed a high maximum adsorption capacity of up to 203 mg/g toward NNK under sonication, which was among the highest values reported. The adsorbed NNK could be removed from the polymer by soaking it in acetonitrile, enabling the adsorbent to be reused. A similar extraction efficiency to that under sonication could be achieved using the polymer-coated magnetic particles under stirring. We also proved that the material could efficiently extract TSNAs from real tobacco extract. This work not only provides an efficient material for the extraction of TSNAs but also offers a design strategy for efficient adsorbents.

Two novel aliphatic unsaturated alcohols isolated from a pathogenic fungus Fusarium proliferatum.

Phytopathogenic fungi have attracted great attention as a promising source for new drug discovery. In the progress of our ongoing study for bioactive natural products from an in-house phytopathogenic fungi library, a pathogenic fungus, Fusarium proliferatum strain 13294 (FP13294), was selected for chemical investigation. Two novel aliphatic unsaturated alcohols named fusariumnols A and B (1 and 2), together with one previously characterized sesquiterpenoid lignoren (3) were identified. Structures of 1-3 were assigned by mass spectrometry and NMR spectroscopy. Their bioactivities were assessed against Staphylococcus epidermidis, S. aureus, and Methicillin-resistant S. aureus (MRSA). Compounds 1 and 2 exhibited weak antibacterial activity against S. epidermidis (MIC = 100 µM).

Metallocalix[4]arene Polymers for Gravimetric Detection of N-Nitrosodialkylamines.

N-Nitrosamines are found in food, drugs, air, water, and soil. They pose a significant risk to human health because of their carcinogenicity; consequently, materials that can be used to selectively and sensitively detect nitrosamines are needed. In this work, we designed and synthesized two polymers bearing calix[4]arene or 4-tert-butylcalix[4]arene tungsten-imido complexes (PCalixH and PCalixtBu) as N-nitrosodimethylamine (NDMA) receptors. The interaction between metallocalix[4]arene monomers/polymers and NDMA was confirmed by 1H NMR and IR spectroscopy. Single-crystal X-ray analysis further revealed that the host-guest interaction is based on binding of the terminal oxygen of NDMA to tungsten within the calixarene cavity. Gravimetric detection of NDMA was performed on a quartz crystal microbalance (QCM) in air. Both polymers show responses to NDMA, with PCalixtBu exhibiting a low theoretical limit of detection of 5 ppb for NDMA. The sensor also shows high selectivity toward NDMA and moderate humidity tolerance. This work provides a sensitive sensor for detection of NDMA and also offers a class of new, selective, and efficient NDMA receptors for the future design of NDMA sensors and NDMA extraction materials.

Unfolding of Helical Poly(L-Glutamic Acid) in N,N-Dimethylformamide Probed by Pyrene Excimer Fluorescence (PEF).

The denaturation undergone by α-helical poly(L-glutamic acid) (PLGA) in N,N-dimethylformamide upon addition of guanidine hydrochloride (GdHCl) was characterized by comparing the fluorescence of a series of PLGA constructs randomly labeled with the dye pyrene (Py-PLGA) to that of a series of Py-PDLGA samples prepared from a racemic mixture of D,L-glutamic acid. The process of pyrene excimer formation (PEF) was taken advantage of to probe changes in the conformation of α-helical Py-PLGA. Fluorescence Blob Model (FBM) analysis of the fluorescence decays of the Py-PLGA and Py-PDLGA constructs yielded the average number () of glutamic acids located inside a blob, which represented the volume probed by an excited pyrenyl label. remained constant for randomly coiled Py-PDLGA but decreased from ~20 to ~10 glutamic acids for the Py-PLGA samples as GdHCl was added to the solution. The decrease in reflected the decrease in the local density of PLGA as the α-helix unraveled in solution. The changes in with GdHCl concentration was used to determine the change in Gibbs energy required to denature the PLGA α-helix in DMF. The relationship between and the local density of macromolecules can now be applied to characterize the conformation of macromolecules in solution.

Genome-guided investigation of anti-inflammatory sesterterpenoids with 5-15 trans-fused ring system from phytopathogenic fungi.

Fungal terpenoids catalyzed by bifunctional terpene synthases (BFTSs) possess interesting bioactive and chemical properties. In this study, an integrated approach of genome mining, heterologous expression, and in vitro enzymatic activity assay was used, and these identified a unique BFTS sub-clade critical to the formation of a 5-15 trans-fused bicyclic sesterterpene preterpestacin I (1). The 5-15 bicyclic BFTS gene clusters were highly conserved but showed relatively wide phylogenetic distribution across several species of the diverged fungal classes Dothideomycetes and Sordariomycetes. Further genomic organization analysis of these homologous biosynthetic gene clusters from this clade revealed a glycosyltransferase from the graminaceous pathogen Bipolaris sorokiniana isolate BS11134, which was absent in other 5-15 bicyclic BFTS gene clusters. Targeted isolation guided by BFTS gene deletion led to the identification of two new sesterterpenoids (4, and 6) from BS11134. Compounds 2 and 4 showed moderate effects on LPS-induced nitrous oxide production in the murine macrophage-like cell line RAW264.7 with in vitro inhibition rates of 36.6 ± 2.4% and 24.9 ± 2.1% at 10 µM, respectively. The plausible biosynthetic pathway of these identified compounds was proposed as well. This work revealed that phytopathogenic fungi can serve as important sources of active terpenoids via systematic analysis of the genomic organization of BFTS biosynthetic gene clusters, their phylogenetic distribution in fungi, and cyclization properties of their metabolic products. KEY POINTS: • Genome mining of the first BFTS BGC harboring a glycosyltransferase. • Gene-deletion guided isolation revealed three novel 5-15 bicyclic sesterterpenoids. • Biosynthetic pathway of isolated sesterterpenoids was proposed.

Molecular networking assisted discovery and biosynthesis elucidation of the antimicrobial spiroketals epicospirocins.

Two pairs of dibenzospiroketal racemates, (±)-epicospirocin A (1a/1b) and (±)-1-epi-epicospirocin A (2a/2b), and two (+)-enantiomers of aspermicrones, ent-aspermicrone B (3b) and ent-aspermicrone C (4b), together with two hemiacetal epimeric mixtures, epicospirocin B/1-epi-epicospirocin B (5/6) and epicospirocin C/1-epi-epicospirocin C (7/8), were investigated from the phytopathogenic fungus Epicoccum nigrum 09116 via MS/MS molecular networking guided isolation and chiral separation for the first time. A plausible epicospirocin biosynthetic pathway was elucidated through in silico gene function annotation together with knock-out experiments. This is the first report that has applied MS/MS molecular networking to identify intermediates correlated with a biosynthetic pathway.

Concise Chemistry Modulation of the SMM Behavior within a Family of Mononuclear Dy(III) Complexes.

By means of the facile chemistry, structural assembly, and transformation of four mononuclear Dy(III) complexes, Dy(bpad)3·CH3OH·H2O (1), Dy(bpad)2(H2O)2·NO3 (2), [Dy(bpad)2(tmhd)] (3), and [Dy(bpad)2(btfa)] (4) (Hbpad = N3-benzoylpyridine-2-carboxamidrazone, tmhd = 2,2,6,6-tetramethylheptane-3,5-dione, btfa = 3-benzoyl-1,1,1-trifluoroacetone), with distinct architectures and local symmetries were established. The disparity of the coordination geometries around the Dy(III) ion among these complexes impacts the strength of the crystal field and the local tensor of anisotropy ( D) of each Dy site and their relative orientations, therefore giving rise to diverse SIM behaviors with distinguishing relaxation energy barriers of 106.93 K for 1, 52.55 K for 2, 48.16 K for 3, and 51.41 K for 4. The differences of the magnetic property and the magnetic anisotropy for four complexes have been explained by ab initio calculations, which are corresponding to the experimental results.