Sustainable and Safe N-alkylation of N-heterocycles by Propylene Carbonate under Neat Reaction Conditions.

A new, eco-friendly process utilising the green solvent propylene carbonate (PC) has been developed to perform N-alkylation of N-, O- and/or S-containing heterocyclic compounds. PC in these reactions served as both the reagent and solvent. Importantly, no genotoxic alkyl halides were required. No auxiliary was necessary when using anhydrous PC. Product formation includes nucleophilic substitution with the concomitant loss of water and carbon dioxide. Substrates prepared, including the newly invented PROTAC drugs, are widely used.

A novel antifungal nanoemulsion based on reuterin-assisted synergistic essential oils: Preparation and in vitro/in vivo characterization.

This research aimed to develop, optimize, and evaluate a new antifungal nanoemulsion system based on the crude reuterin-synergistic essential oils (EOs) hybrid to overcome the EOs application limits. At first, the antifungal effects of the Lactobacillus plantarum and Lactobacillus reuteri cell-free extracts (CFE) were tested against the Botrytis cinerea, Penicillium expansum, and Alternaria alternata as indicator fungus using broth microdilution method. The L. reuteri CFE with the MIC of 125 µL/mL for B. cinerea and 250 µL/mL for P. expansum and A. alternata showed more inhibitory effects than L. plantarum. Next, reuterin as a significant antibacterial compound in the L. reuteri CFE was induced in glycerol-containing culture media. To reach a nanoemulsion with maximum antifungal activity and stability, the reuterin concentration, Tween 80 %, and ultrasound time were optimized using response surface methodology (RSM) with a volumetric constant ratio of 5 % v/v oil phase including triple synergistic EOs (thyme, cinnamon, and rosemary) at MIC concentrations. Based on the Box-Behnken Design, the maximum antifungal effect was observed in the treatment with 40 mM reuterin, 1 % Tween 80, and 3 min of ultrasound. The growth inhibitory diameter zones of B. cinerea, P. expansum, and A. alternata were estimated 6.15, 4.25, and 4.35 cm in optimum nanoemulsion, respectively. Also, the minimum average particle size diameter (16.3 nm) was observed in nanoemulsion with reuterin 40 mM, Tween 80 5 %, and 3 min of ultrasound treatment. Zeta potential was relatively high within -30 mV range in all designed nanoemulsions which indicates the nanoemulsion's stability. Also, the prepared nanoemulsions, despite initial particle size showed good stability in a 90-d storage period at 25 °C. In vivo assay, showed a significant improvement in the protection of apple fruit treated with reuterin-EOs nanoemulsions against fungal spoilage compared to free reuterin nanoemulsion. Treatment of apples with nanoemulsion containing 40 mM reuterin showed a maximum inhibitory effect on B. cinerea (5.1 mm lesion diameter compared to 29.2 mm for control fruit) within 7 d at 25 °C. In summary, the present study demonstrated that reuterin-synergistic EOs hybrid with boosted antifungal activities can be considered as a biopreservative for food applications.

Abiotic natural attenuation of 1,2,3-trichloropropane by natural magnetite under O2 perturbation.

1,2,3-Trichloropropane (TCP) is an emerging groundwater pollutant, but there is a lack of reported studies on the abiotic natural attenuation of TCP by iron minerals. Furthermore, perturbation by O2 is common in the shallow subsurface by both natural and artificial processes. In this study, natural magnetite was selected as the reactive iron mineral to investigate its role in the degradation of TCP under O2 perturbation. The results indicated that the mineral structural Fe(II) on magnetite reacted with dissolved oxygen to generate O2-· and HO·. Both O2-· and HO· contributed to TCP degradation, with O2-· playing a more important role. After 56 days of reaction, 66.7% of TCP was completely dechlorinated. This study revealed that higher magnetite concentrations, smaller magnetite particle sizes, and lower initial TCP concentrations favored TCP degradation. The presence of <10 mg/L natural organic matter (NOM) did not affect TCP degradation. These findings significantly advance our understanding of the abiotic natural attenuation mechanisms facilitated by iron minerals under O2 perturbation, providing crucial insights for the study of natural attenuation.

Dendritic Mesoporous Silica Nanoparticle Supported PtSn Catalysts for Propane Dehydrogenation.

PtSn catalysts were synthesized by incipient-wetness impregnation using a dendritic mesoporous silica nanoparticle support. The catalysts were characterized by XRD, N2 adsorption-desorption, TEM, XPS and Raman, and their catalytic performance for propane dehydrogenation was tested. The influences of Pt/Sn ratios were investigated. Changing the Pt/Sn ratios influences the interaction between Pt and Sn. The catalyst with a Pt/Sn ratio of 1:2 possesses the highest interaction between Pt and Sn. The best catalytic performance was obtained for the Pt1Sn2/DMSN catalyst with an initial propane conversion of 34.9%. The good catalytic performance of this catalyst is ascribed to the small nanoparticle size of PtSn and the favorable chemical state and dispersion degree of Pt and Sn species.

An Atomistic Picture of Boron Oxide Catalysts for Oxidative Dehydrogenation Revealed by Ultrahigh Field 11B-17O Solid-State NMR Spectroscopy.

Boron oxide/hydroxide supported on oxidized activated carbon (B/OAC) was shown to be an inexpensive catalyst for the oxidative dehydrogenation (ODH) of propane that offers activity and selectivity comparable to boron nitride. Here, we obtain an atomistic picture of the boron oxide/hydroxide layer in B/OAC by using 35.2 T 11B and 17O solid-state NMR experiments. NMR spectra measured at 35.2 T resolve the boron and oxygen sites due to narrowing of the central-transition powder patterns. A 35.2 T 2D 11B{17O} dipolar heteronuclear correlation NMR spectrum revealed the structural connectivity between boron and oxygen atoms. The approach outlined here should be generally applicable to determine atomistic structures of heterogeneous catalysts containing quadrupolar nuclei.

Ultramicroporous Hydrogen-Bonded Organic Framework Material with a Thermoregulatory Gating Effect for Record Propylene Separation.

Propane/propylene separation is one of the most challenging and energy-consuming but most important tasks in the petrochemical industry. Herein, a stable hydrogen-bonded organic framework (HOF-FJU-1) was tailor-made for highly efficient propylene separation from binary C3H6/C3H8 and even seven component CH4/C2H4/C2H6/C3H6/C3H8/CO2/H2 mixtures. The temperature-controllable diffusion channels in HOF-FJU-1 have enabled the porous material to completely exclude propane to reach high-performance propylene purification under energy-efficient operation conditions. Single-crystal structural analysis revealed that the well-matched pore aperture of HOF-FJU-1 can exactly accommodate propylene molecules via multiple intermolecular interactions, exhibiting a very high propylene/propane selectivity of 616 at 333 K. The propylene purity and productivity are over 99.5% and 30.2 L kg-1 from the binary C3H6/C3H8 (50/50) mixture at 333 K. Through a follow-up column separation of C3H6/C2H4 at 353 K, not only high-purity propylene (99.5%) but also ethylene (98.3%) can be readily collected from the seven component CH4/C2H4/C2H6/C3H6/C3H8/CO2/H2 (31/10/25/10/10/1/13) cracking gas mixtures. The great potential of HOF-FJU-1 for the industrial propylene separation process has been further supported by the high stability of this porous material under different environments and straightforward processibility and regeneration feasibility.

Modulation of ODH Propane Selectivity by Zeolite Support Desilication: Vanadium Species Anchored to Al-Rich Shell as Crucial Active Sites.

The commercially available zeolite HY and its desilicated analogue were subjected to a classical wet impregnation procedure with NH4VO3 to produce catalysts differentiated in acidic and redox properties. Various spectroscopic techniques (in situ probe molecules adsorption and time-resolved propane transformation FT-IR studies, XAS, 51V MAS NMR, and 2D COS UV-vis) were employed to study speciation, local coordination, and reducibility of the vanadium species introduced into the hierarchical faujasite zeolite. The acid-based redox properties of V centres were linked to catalytic activity in the oxidative dehydrogenation of propane. The modification of zeolite via caustic treatment is an effective method of adjusting its basicity-a parameter that plays an important role in the ODH process. The developed mesopore surface ensured the attachment of vanadium species to silanol groups and formation of isolated (SiO)2(HO)V=O and (SiO)3V=O sites or polymeric, highly dispersed forms located in the zeolite micropores. The higher basicity of HYdeSi, due to the presence of the Al-rich shell, aided the activation of the C-H bond leading to a higher selectivity to propene. Its polymerisation and coke formation were inhibited by the lower acid strength of the protonic sites in desilicated zeolite. The Al-rich shell was also beneficial for anchoring V species and thus their reducibility. The operando UV-vis experiments revealed higher reactivity of the bridging oxygens V-O-V over the oxo-group V=O. The (SiO)3V=O species were found to be ineffective in propane oxidation when temperature does not exceed 400 °C.

Chitosan scaffolds with enhanced mechanical strength and elastic response by combination of freeze gelation, photo-crosslinking and freeze-drying.

In this study, a new scaffold fabrication method based on the combination of a series of stabilization processes was set up to obtain chitosan scaffolds with improved mechanical properties for regeneration of load-bearing tissues. Specifically, thermally induced phase separation (TIPS) of chitosan solutions was used to obtain an open structure which was then stabilized by freeze-gelation and photo cross-linking. Freeze-gelation combined with freeze-drying permitted to obtain a porous structure with a 95 µm-mean pore size suitable for osteoblast cells' housing. Photo-crosslinking improved by ca. three times the scaffold compressive modulus, passing from 0,8 MPa of the uncrosslinked scaffolds to 2,2 MPa of the crosslinked one. Hydrated crosslinked scaffolds showed a good elastic response, with an 80% elastic recovery for at least 5 consecutive compressive cycles. The herein reported method has the advantage to not require the use of potentially toxic cross-linking agents and may be extended to other soft materials.

3-Hydroxypropionic acid contributes to the antibacterial activity of glycerol metabolism by the food microbe Limosilactobacillus reuteri.

Strains of Limosilactobacillus reuteri are used as starter and bioprotective cultures and contribute to the preservation of food through the production of fermentation metabolites lactic and acetic acid, and of the antimicrobial reuterin. Reuterin consists of acrolein and 3-hydroxypropionaldehyde (3-HPA), which can be further metabolized to 1,3-propanediol and 3-hydroxypropionic acid (3-HP). While reuterin has been the focus of many investigations, the contribution of 3-HP to the antimicrobial activity of food related reuterin-producers is unknown. We show that the antibacterial activity of 3-HP was stronger at pH 4.8 compared to pH 5.5 and 6.6. Gram-positive bacteria were in general more resistant against 3-HP and propionic acid than Gram-negative indicator strains including common food pathogens, while spoilage yeast and molds were not inhibited by ≤ 640 mM 3-HP. The presence of acrolein decreased the minimal inhibitory activity of 3-HP against E. coli indicating synergistic antibacterial activity. 3-HP was formed during the growth of the reuterin-producers, and by resting cells of L. reuteri DSM 20016. Taken together, this study shows that food-related reuterin producers strains synthesize a second antibacterial compound, which might be of relevance when strains are added as starter or bioprotective cultures to food products.

3-Hydroxy-propanamidines, a New Class of Orally Active Antimalarials Targeting Plasmodium falciparum.

3-Hydroxypropanamidines are a new promising class of highly active antiplasmodial agents. The most active compound 22 exhibited excellent antiplasmodial in vitro activity with nanomolar inhibition of chloroquine-sensitive and multidrug-resistant parasite strains ofPlasmodium falciparum (with IC50 values of 5 and 12 nM against 3D7 and Dd2 strains, respectively) as well as low cytotoxicity in human cells. In addition, 22 showed strong in vivo activity in thePlasmodium berghei mouse model with a cure rate of 66% at 50 mg/kg and a cure rate of 33% at 30 mg/kg in the Peters test after once daily oral administration for 4 consecutive days. A quick onset of action was indicated by the fast drug absorption shown in mice. The new lead compound was also characterized by a high barrier to resistance and inhibited the heme detoxification machinery in P. falciparum.

Deoxyribonuclease I Inhibitory Properties, Molecular Docking and Molecular Dynamics Simulations of 1-(Pyrrolidin-2-yl)propan-2-one Derivatives.

Deoxyribonuclease I (DNase I) inhibitory properties of two 1-(pyrrolidin-2-yl)propan-2-one derivatives were examined in vitro. Determined IC50 values of 1-[1-(4-methoxyphenyl)pyrrolidin-2-yl]propan-2-one (1) (192.13±16.95 µM) and 1-[1-(3,4,5-trimethoxyphenyl)pyrrolidin-2-yl]propan-2-one (2) (132.62±9.92 µM) exceed IC50 value of crystal violet, used as a positive control, 1.89- and 2.73-times, respectively. Compounds are predicted to be nontoxic and to have favorable pharmacokinetic profiles, with high gastrointestinal absorption and blood-brain barrier permeability. Molecular docking and molecular dynamics simulations suggest that interactions with Glu 39, Glu 78, Arg 111, Pro 137, Asp 251 and His 252 are an important factor for inhibitors affinity toward the DNase I. Determined inhibitory properties along with predicted ADMET profiles and observed interactions would be beneficial for the discovery of new active 1-(pyrrolidin-2-yl)propan-2-one-based inhibitors of DNase I.

Exploring the copper binding ability of Mets7 hCtr-1 protein domain and His7 derivative: An insight in Michael addition catalysis.

Mets7 is a methionine-rich motif present in hCtr-1 transporter that is involved in copper cellular trafficking. Its ability to bind Cu(I) was recently exploited to develop metallopeptide catalysts for Henry condensation. Here, the catalytic activity of Mets7-Cu(I) complex in Michael addition reactions has been evaluated. Furthermore, His7 peptide, in which Met residues have been substituted with His ones, was also prepared. This substitution allowed His7 to coordinate Cu (II), with the obtainment of a stable turn conformation as evicted by CD experiments. His7-Cu (II) proved also to be a better catalyst than Mets7-Cu(I) in the addition reaction. In particular, when the substrate was the (E)-1-phenyl-3-(pyridin-2-yl)prop-2-en-1-one, a conversion of 71% and a significative 58% of e.e. was observed.

A procedure and double-chambered device for macromolecular crystal flash-cooling in different cryogenic liquids.

Flash-cooling of macromolecular crystals for X-ray diffraction analysis is usually performed in liquid nitrogen (LN2). Cryogens different than LN2 are used as well for this procedure but are highly underrepresented, e.g., liquid propane and liquid ethane. These two cryogens have significantly higher cooling rates compared with LN2 and may thus be beneficial for flash-cooling of macromolecular crystals. Flash-cooling in liquid propane or liquid ethane results in sample vitrification but is accompanied by solidification of these cryogens, which is not compatible with the robotic systems nowadays used for crystal mounting at most synchrotrons. Here we provide a detailed description of a new double-chambered device and procedure to flash-cool loop mounted macromolecular crystals in different cryogenic liquids. The usage of this device may result in specimens of better crystal- and optical quality in terms of mosaic spread and ice contamination. Furthermore, applying the described procedure with the new double-chambered device provides the possibility to screen for the best flash-cooling cryogen for macromolecular crystals on a routine basis, and, most importantly, the samples obtained allow the usage of state-of-the-art robotic sample-loading systems at synchrotrons.

Discovery of Diphenoxy Derivatives with Flexible Linkers as Ligands for ß-Amyloid Plaques.

The highly rigid and planar scaffolds with π-conjugated systems have been widely considered to be indispensable for ß-amyloid (Aß) binding ligands. In this study, a library of diphenoxy compounds with different types of more flexible linkers as Aß ligands were synthesized and evaluated. Most of them displayed good affinity (Ki < 100 nM) for Aß1-42 aggregates, and some ligands even showed values of Ki less than 10 nM. Structure-activity relationship analysis revealed that modification on the linkers or substituents tolerated great flexibility, which challenged the long-held belief that rigid and planar structures are exclusively favored for Aß binding. Three ligands were labeled by iodine-125, and they exhibited good properties in vitro and in vivo, which further supported that this flexible scaffold was potential and promising for the development of Aß imaging agents.

Conversion of the Propane-Butane Fraction into Arenes on MFI Zeolites Modified by Zinc Oxide and Activated by Low-Temperature Plasma.

The effect of modification of MFI zeolite 1-5 wt.% ZnO activated by plasma on acid and catalytic properties in the conversion of the propane-butane fraction into arenes was investigated. The high-silica zeolites with silicate module 45 were synthesized from alkaline alumina-silica gels in the presence of an 'X-oil' organic structure-forming additive. The modification of the zeolite with zinc was carried out by impregnating the zeolite granules in the H-form with an aqueous solution of Zn(NO3)2. The obtained zeolites were characterized by X-ray phase analysis and IR spectroscopy. It is shown that the synthesized zeolites belong to the high-silica MFI zeolites. The study of microporous zeolite-containing catalysts during the conversion of C3-C4 alkanes to aromatic hydrocarbons made it possible to establish that the highest yield of aromatic hydrocarbons is observed on zeolite catalysts modified with 1 and 3% ZnO and amount to 63.7 and 64.4% at 600 °C, respectively, which is 7.7-8.4% more than on the original zeolite. The preliminary activation of microporous zeolites modified with 1-5% ZnO and plasma leads to an increase in the yield of aromatic hydrocarbons from the propane-butane fraction; the maximum yield of arenes is observed in zeolite catalysts modified with 1 and 3% ZnO and activated by plasma, amounting to 64.9 and 65.5% at 600 °C, respectively, which is 8.9-9.5% more than on the initial zeolite. The activity of the zeolite catalysts modified by ZnO and activated by plasma show good agreement with their acid properties. Activation of the zeolites modified by 1 and 3% ZnO and plasma leads to an increase in the concentration of the weak acid sites of the catalyst to 707 and 764 mmol/g in comparison with plasma-inactivated 1 and 3% ZnO/ZKE-XM catalysts at 626 and 572 mmol/g, respectively.

Effects of Irgacure 2959 and lithium phenyl-2,4,6-trimethylbenzoylphosphinate on cell viability, physical properties, and microstructure in 3D bioprinting of vascular-like constructs.

Photocrosslinkable polymers such as gelatin methacrylate (GelMA) have various 3D bioprinting applications. These polymers crosslink upon exposure to UV irradiation with the existence of an appropriate photoinitiator. Two photoinitiators, Irgacure 2959 and lithium phenyl-2,4,6-trimethylbenzoylphosphinate (LAP) are commonly used. This study systematically investigates the effects of photoinitiator types on the cell viability, physical properties, and microstructure in 3D bioprinting of GelMA-based cellular constructs. The main conclusions are: (1) during the 3D bioprinting, the cell viability generally decreases as the photoinitiator concentration and printing time increase using both Irgacure 2959 and LAP. At the low photoinitiator concentrations (such as 0.3% and 0.5% (w/v)), the overall cell viability is good within the printing time of 60 min using both Irgacure 2959 and LAP. However, at the high photoinitiator concentrations (such as 0.7% and 0.9% (w/v)), the overall cell viability using LAP is much higher than that using Irgacure 2959 within the printing time of 60 min; (2) after the 3D bioprinting, the photoinitiator types, either Irgacure 2959 or LAP, have negligible effects on the post-printing cell viability after crosslinking; (3) after the 3D bioprinting, GelMA samples cured with Irgacure 2959 have slightly larger pore size, faster degradation rate, and greater swelling ratio compared to those cured with LAP; (4) 3D GelMA-based vascular-like constructs have been fabricated using dynamic optical projection stereolithography, and the measured dimensions have been compared with the designed dimensions showing good shape fidelity.

Design and synthesis of a new furan-steroid-propanone derivative using some chemical strategies.

There are several reports for the preparation of furan derivatives using some protocols which requires special conditions. In this way, the aim of this study was to synthesize a new furan-steroid-propanone derivative from both 17α-ethynylestradiol and 2-nitro-17α-ethynylestradiol using some series of reactions such as aldolization, 2 + 2 addition and etherification. The chemical structure was evaluated through both 1H NMR and 13C NMR spectroscopic analysis. The results showed a good yielding from furan-steroid derivative. In conclusion, this investigation provides a facile synthesis of a new furan-steroid-propanone derivative, using some reagents which are not expensive and do not require special conditions for handling.

In situ preparation of gold-polyester nanoparticles for biomedical imaging.

The synthesis and application of gold nanoparticles (AuNPs) have attracted much attention due to their interesting optical and chemical properties, as well as their utility in imaging, therapeutics, sensors, electronics, and catalysis. AuNPs are synthesized using multiple approaches, followed by chemical modification or encapsulation, to enhance their colloidal stability, biocompatibility, and targeting. Here, we report the one-step synthesis of gold-polyester nanoparticles for use as an imaging agent. The AuNPs were prepared inside polymeric NPs by means of ultraviolet irradiation of a gold salt in the presence of Irgacure I-2959 photoinitiator. We monitored the kinetic growth and nucleation of AuNPs (in vitro and ex vivo) over time using spectral analysis. Moreover, we investigated the cytotoxicity, localized plasmonic surface resonance (LSPR), and cellular imaging capabilities of the Au-polyester nanoparticles. The resulting Au-polyester NPs were characterized by Fourier transform infrared spectroscopy (FTIR), thermogravimetric analysis (TGA), X-ray diffraction (XRD), dynamic light scattering (DLS), and transmission electron microscopy (TEM) to probe their chemical structure, size, zeta potential (ζ), and morphology, respectively. Furthermore, in vitro experiments showed that the NP formulation is stable over time and exhibits negligible toxicity against 3T3 fibroblast and U-87 MG glioblastoma cells. The results also demonstrated that the Au-polyester NPs exhibit excellent cellular imaging properties. This one-step strategy goes beyond current syntheses of gold-polyester nanoparticles because it can be used to synthesize the imaging agent in situ (i.e., in living cells) in lieu of conventional ex situ approaches.

The New Salicylaldehyde S,S-Propanedithioacetal Ester Enables N-to-C Sequential Native Chemical Ligation and Ser/Thr Ligation for Chemical Protein Synthesis.

The combination of distinct peptide ligation techniques to facilitate chemical protein synthesis represents one of the long-standing goals in the field. A new combination ligation method of N-to-C sequential native chemical ligation and Ser/Thr ligation (NCL-STL) is described for the first time. This method relies on the peptide salicylaldehyde S,S-propanedithioacetal (SALPDT)-ester prepared by a new 1,3-propanedithiol-mediated reaction. The peptide SALPDT-ester, which is compatible with NCL, can be fully activated by N-chlorosuccinimide (NCS)/AgNO3 in aqueous solution to afford peptide SAL-ester for use in the subsequent STL. The practicality of the combined NCL-STL method is illustrated by the synthesis of S-palmitoylated matrix-2 (S-palm M2) ion channel from Influenza A virus and S-palmitoylated interferon-induced transmembrane protein 3 (S-palm IFITM3). This approach expands the multiple-segments peptide ligation toolkit for producing important and complex custom-made protein samples by chemical protein synthesis.

Oxidative Dehydrogenation of Propane over Vanadium-Containing Faujasite Zeolite.

Oxidative dehydrogenation (ODH) of light alkanes to olefins-in particular, using vanadium-based catalysts-is a promising alternative to the dehydrogenation process. Here, we investigate how the activity of the vanadium phase in ODH is related to its dispersion in porous matrices. An attempt was made to synthesize catalysts in which vanadium was deposited on a microporous faujasite zeolite (FAU) with the hierarchical (desilicated) FAU as supports. These yielded different catalysts with varying amounts and types of vanadium phase and the porosity of the support. The phase composition of the catalysts was confirmed by X-ray diffraction (XRD); low temperature nitrogen sorption experiments resulted in their surface area and pore volumes, and reducibility was measured with a temperature-programmed reduction with a hydrogen (H2-TPR) method. The character of vanadium was studied by UV-VIS spectroscopy. The obtained samples were subjected to catalytic tests in the oxidative dehydrogenation of propane in a fixed-bed gas flow reactor with a gas chromatograph to detect subtract and reaction products at a temperature range from 400-500 °C, with varying contact times. The sample containing 6 wt% of vanadium deposited on the desilicated FAU appeared the most active. The activity was ascribed to the presence of the dispersed vanadium ions in the tetragonal coordination environment and support mesoporosity.