Efficient Synthesis of 2’-O-Methoxyethyl Oligonucleotide-Cationic Peptide Conjugates

Single-stranded phosphorothioate (PS) oligonucleotide drugs have shown potential for the treatment of several rare diseases. However, a barrier to their widespread use is that they exhibit activity in only a narrow range of tissues. One way to circumvent this constraint is to conjugate them to cationic cell-penetrating peptides (CPPs). Although there are several examples of morpholino and peptide nucleic acids conjugated with CPPs, there are noticeably few examples of PS oligonucleotide-CPP conjugates. This is surprising given that PS oligonucleotides presently represent the largest class of approved RNA-based drugs, including Nusinersen, that bears the 2’-O-methoxyethyl (MOE)-chemistry. In this work, we report a method for in-solution conjugation of cationic, hydrophobic peptides or human serum albumin to a 22-nucleotide MOE-PS oligonucleotide. Conjugates were obtained in high yields and purities. Our findings pave the way for their large-scale synthesis and testing in vivo.     

Efficient Chemoenzymatic Synthesis of N-Glycans with a β1,4-Galactosylated Bisecting GlcNAc Motif

In human serum immunoglobulin G (IgG), a rare modification of biantennary complex N-glycans lead to a β1,4-galactosylated bisecting GlcNAc branch. We found that the bisecting GlcNAc on a biantennary core-fucosylated N-glycan was enzymatically galactosylated under stringent reaction conditions. Further optimizations led to an efficient enzymatic approach to this particular modification for biantennary substrates. Notably, tri- and tetra-antennary complex N-glycans were not converted by bovine galactosyltransferase. An N-glycan with a galactosylated bisecting GlcNAc was linked to a lanthanide binding tag. The pseudo-contact shifts (PCS) obtained from the corresponding Dy-complex were used to calculate the conformational preferences of the rare N-glycan. Besides two extended conformations only a single folded conformation was found.     

Synthesis of activated carbon with highly developed “mesoporosity”

Mesoporous carbons are very promising materials in research fields dealing with large molecules (e.g. catalysis and biomedical applications). However, recent hard and soft template technologies to produce them exhibit important drawbacks associated with the high-cost of the template and scale-up. Here, we report the synthesis of activated carbon materials with a highly developed pore volume in the range of mesoporosity (up to 1 cm³/g) when combining physical and chemical activation of a lignocellulosic precursor (olive stones) and CaCl₂ as chemical reactant.     

Synthesis of exfoliated polyaniline–clay nanocomposite in supercritical CO2

This paper presents the works done to synthesize fully exfoliated polyaniline–clay nanocomposites (PCNs) with high purity via in situ polymerization of aniline in Cloisite 30B nano-clay suspension in supercritical CO₂ (ScCO₂) medium. The Cloisite 30B was first delaminated with ScCO₂ treatment in the presence of aniline monomers. Ammonium peroxydisulfate (APS) solution was added rapidly into the mixture of delaminated Cloisite 30B and aniline monomers to produce PCNs. Scanning electron microscopy (SEM), Fourier transform infrared spectroscopy (FTIR), UV–vis spectroscopy and XRD analysis have been used to characterize the morphology and structure of the as-synthesized product. SEM results reveal that nano-clays are fully exfoliated in the final nanocomposite which is synthesized in ScCO₂. FTIR and UV–vis analysis showed that the resulted polyaniline (PANI) had been in highly conductive emeraldine salt state and ScCO₂ does not have any effect on chemical structures of the PANI.     

Effects of Process Variables on Microcellular Structure and Crystallization of Polypropylene Foams with Supercritical CO2 as the Foaming Agent—A Study of Microcellular Foaming of Polypropylene

The effects of process variables on the microcellular structure and crystallization of foamed polypropylene (PP) with supercritical CO₂ as the foaming agent were investigated in this article. The cell size increased and the cell density reduced with increased foaming temperature. Differently, both the cell diameter and cell density increased as saturation pressure increased. DSC curves showed that the melting peak was broadened when supercritical CO₂ foaming PP. Furthermore, the width at half-height of the melting peak increased, the melting peak moved to higher temperature, and the melting point and crystallinity enhanced as the foaming temperature lowered and the saturation pressure enhanced.     

Selective Oxidation of 1- and 2-Propanol with Molecular Oxygen by Noble Metal Catalysis in “Supercritical” Carbon Dioxide

The selective oxidation of 1- and 2-propanol by molecular oxygen over supported platinum catalysts was investigated in supercritical carbon dioxide as an environmentally benign and safe reaction medium. The reaction occurs exclusively to acetone or propionic aldehyde and propionic acid in a single-phase region at 100–190 bar and at a mild temperature (40 °C). Compared to conversions in aqueous solution, catalyst stability is significantly enhanced in supercritical carbon dioxide and depends on the oxygen concentration in the reaction medium. Thus, at least a fourfold higher substrate/catalyst ratio than with water as a solvent can be used. Platinum catalysts with nanoporous silica (MCM-41, silicalite-1) as a support are also active for the oxidation of 2-propanol in supercritical carbon dioxide.     

Synthesis of exfoliated conductive polyaniline–graphite nanocomposites in supercritical CO2

Exfoliated polyaniline–graphite nanocomposites with high electrical conductivity were synthesized. Graphite powders were first expanded with ScCO₂ treatment and then aniline monomers were added to the suspension. The morphology and structure of the synthesized products were characterized by scanning electron microscopy (SEM), transmission electron microscopy (TEM), Fourier transform infrared spectroscopy (FTIR), UV/Vis spectroscopy and XRD analysis. SEM and TEM micrographs revealed that graphite was successfully expanded through ScCO₂ treatment, and the graphite powders are fully exfoliated in the final nanocomposite. FTIR results confirmed formation of polyaniline (PANI), and UV/Vis analysis showed the conductive emeraldine state of the synthesized PANI. Furthermore, it was clearly demonstrated that ScCO₂ medium does not have any effect on chemical structures of the PANI. The electrical conductivities of the PGNs enhanced dramatically with increasing graphite loading up to 40% and subsequently decreased due to the weaker bridged linkage between PANI and graphite layers at high graphite loading.     

Efficient and Mild Synthesis of Novel Diazo Dyes through Coupling Reaction of Schiff Base Diazonium Salts with β-naphthol

In this study, efficient and mild method for synthesis of some novel diazo dyes containing Schiff bases has been reported. All of the intermediates and final products were obtained in good to high yields and appropriate reaction times. The structures of desired products were determined using physical and spectroscopy data such as; IR, ¹H NMR, ¹³C NMR, mass spectra, and C.H.N. analyses. The worldwide availability, larger scale synthesis, high yields, and short reaction times are the advantages of the present method.     

Efficient Biocatalytic Synthesis of Highly Enantiopure α-Alkylated Arylglycines and Amides

A number of racemic α-alkylarylglycine amides including 1-amino-1-carbamoyl-1,2,3,4-tetrahydronaphthalene underwent efficient biocatalytic hydrolysis under very mild conditions to afford the corresponding (S)-α-alkylarylglycines and (R)-α-alkylarylglycine amides in excellent yields with enantiomeric excesses higher than 99.5%. Both the reaction rate and enantioselectivity of biocatalytic kinetic resolution were strongly dependent upon the nature of the substituent and the substitution pattern on the benzene ring of the substrate. In contrast, no effective biotransformation of the Strecker nitrile derived from acetophenone was observed under the catalysis of a nitrile hydratase/amidase-containing microbial Rhodococcus sp. AJ270 whole-cell catalyst. Coupled with the chemical hydrolysis of amide, this biotransformation process provided efficient syntheses of α-substituted arylglycines in both enantiomeric forms from readily available racemic amides.     

“Spontaneous Copolymerization of p-Chlorophenylmaleimide with 2-Methylaziridine”

Abstract

p-Chlorophenylmaleimide as an electrophilic monomer was copolymerized in the absence of initiator with 2-methylaziridine as nuclephilic monomer. The copolymers were characterized by elemental analysis, FT-IR, and ¹H-NMR spectroscopy. The copolymer compositions were determined by chloro elemental analysis and ¹H-NMR spectroscopy. 2-Methylaziridine is more reactive than p-chlorophenylmaleimide yielding statistical copolymers. Mn, determined by vapor pressure osmometry, varied between 3.000 and 6.700 g/mol.     

Gasification of Brazilian coal-chars with CO2: effect of samples’ properties on reactivity and kinetic modeling

The gasification of coals obtained from important coalfields in Brazil was investigated in 1.0?bar of CO₂ using a thermogravimetric analyzer. Tests were carried out in two sequential steps: pyrolysis under N₂ at 1213 K and isothermal gasification under CO₂ in the temperature range of 1113–1213 K. The kinetic study was performed in the kinetically controlled regime and three gas-solid models were fitted to the experimental data. According to the results, subbituminous coal-chars presented higher reactivities than bituminous types, with maceral and ash compositions playing a key role in the overall process. The reaction rates increased with increasing temperature, with maximum values found in the conversion range of 10–60%. The random pore model that predicts a maximum point of reactivity over the reaction course suitably described the gasification kinetics. Values of activation energy between 146.63(±0.03) kJ/mol and 215.09(±0.05) kJ/mol were found, which are consistent to literature data of coals gasified worldwide. Despite the relatively high ash content (32–45%), the Brazilian coals appeared to be sufficiently reactive to be gasified, thus indicating the significance of this study to the development of gasification process in Brazil.     

Studies of metal–support interactions with “real” and “inverted” model systems: reactions of CO and small hydrocarbons with hydrogen on noble metals in contact with oxides

Two types of model catalysts are compared: thin film catalysts consisting of polyhedral noble metal nanocrystals (Rh and Pt) supported by reducible and non‐reducible oxides, and their inverted pendants, submonolayers of titania and vanadia deposited under UHV conditions on the respective metal surfaces (Pd and Rh(111) and Rh (polycrystalline)). The structure and composition of the inverse catalysts were examined in situ by LEED and AES and the nanoparticles were characterized by HRTEM. The activity of thin film and inverse catalysts was studied in a series of reactions, such as the ring opening of methylcyclopentane and methylcyclobutane, the dissociation of CO and the CO methanation. Reaction conditions comprise atmospheric pressure but also molecular beam experiments. The reaction rates are related to the oxidation state of the supporting oxide, to the free metal surface area and to the number of sites at the interface between metal and support. This revised version was published online in June 2006 with corrections to the Cover Date.     

Synthesis of heterobifunctional polyethylene glycols with azide functionality suitable for “click” chemistry

Mid-to-high molecular weight konjac glucomannan (MHKGM) powders with different molecular weights were prepared and purified from their enzymatic hydrolysis solutions. MHKGM powder yield was optimized with respect to substrate concentration, urea concentration, the number of alcohol washings, and drying temperature. Properties of MHKGM powder were characterized by SEC, FTIR, UV, XRD, rheological, and thermal analysis techniques. The results showed that under the correct conditions a high productive yield of MHKGM can be obtained. MHKGMs have the same chemical structure as that of native KGM, but their weight average molecular weight (M _w), molecular weight distribution index (M _w/M _n), radius of gyration (R _g), solution optical clarity, rheological properties, and other physical properties such as water solubility are very different from those of native KGM. This study provides useful a reference for making MHKGM powder with varying molecular weight and the potential applications of KGM such as healthy food additives.     

Extraction kinetics of pre-pelletized Jalapeño peppers with supercritical CO2

The aim of this work was to assess and model supercritical carbon dioxide (ScCO₂) extraction kinetics of pre-pelletized Jalapeño peppers (Capsicum annuum L.). Pepper flakes were conditioned to low moisture, ground finely and pelletized at high pressure, and pellets were subsequently ground and size classified. The effects of average sample particle size (D_p=0.28–3.19 mm) and superficial solvent velocity (U_s=0.14–2.62 mm s⁻¹) were evaluated at 40 °C and 120 or 320 bar. Extraction rate increased as a result of a decrease in D_p. It also increased as a result of an increase in U_s at 120 bar, but the effect was almost negligible at 320 bar. Integral extraction yields of capsicum oleoresin and capsaicinoids were ≈0.102 g g⁻¹ and ≈240 mg kg⁻¹, respectively, independent of extraction conditions. External mass transfer coefficients (k_f) increased with U_s, but this effect was less pronounced than commonly reported in the literature. Values of k_f increased as D_p or process pressure decreased, due respectively to increments in specific area and improvements in transport properties. Internal mass transfer coefficients, on the other hand, were 5.3×10⁻⁸ m s⁻¹ at 40 °C and 120 bar, and 34.7×10⁻⁸ m s⁻¹ at 40 °C and 320 bar. Solutes were effectively liberated from the original matrix with our multistage pretreatment, so that the fraction of free solute did not depend on D_p (α=0.46). Pseudosolubilities for capsicum oleoresin in ScCO₂ (≈2100 mg l⁻¹ at 40 °C and 120 bar; ≈13,700 mg l⁻¹ solute/CO₂ at 40 °C and 320 bar) were of the same order of magnitude as corresponding true solubilities of capsaicin (5600 and 11,800 mg l⁻¹, respectively). Estimated true solubilities of chlorophyll-a in ScCO₂ (2 mg l⁻¹ at 40 °C and 120 bar; 18 mg l⁻¹ at 40 °C and 320 bar), on the other hand, were orders of magnitude smaller, which justifies a much slower extraction rate for green pigments than pungent compounds. Thus, oleoresin obtained after 4 h at 40 °C and 120 bar had a very attractive light yellow tinge.     

Supercritical carbon dioxide (SC-CO2) dyeing of cellulose acetate: An opportunity for a “greener” circular textile economy

This article compares the dyeing of cellulose diacetate (cellulose-based) and polyester fabrics using supercritical carbon dioxide (SC-CO₂) and aqueous media. The benefits of dyeing in SC-CO₂ were clearly demonstrated in laboratory-based and pilot-scale studies in terms of increased colour strength, uniformity, fastness and the absence of auxiliaries such as dispersing agents or surfactants. In addition, the “super-levelling” nature of the SC-CO₂ medium was demonstrated in the reprocessing of polyester “waste textile” and the re-use of the “locked-in waste” colourant. The SC-CO₂ processing medium can be utilised to accurately colour “multiple life” polyester and cellulose acetate uniformly and to creatively tie-dye polyester and cellulose acetate fabrics. Through SC-CO₂ fluid technology, we can envisage a viable waterless circular manufacturing and recycling/remanufacturing framework for the predominantly polyester global fibre market coupled to the sustainably sourced, biodegradable cellulose diacetate as a replacement for cotton. The key technical and commercial advantages being the use of a single solvent dye class for both polyester and the cellulose diacetate, saving on energy costs, integrated simpler processing, reduced water usage and associated efficient recycling. Further, repositioning the cellulosic fibre industry towards using sustainable forests is attractive in terms of improved land, water and environmental management.     

Efficient removal of Congo red by magnetically separable mesoporous TiO2 modified with γ-Fe2O3

Magnetically separable mesoporous TiO₂ modified with γ-Fe₂O₃ was prepared and characterized by X–ray diffraction, N₂ adsorption–desorption measurements, scanning electron microscopy, UV–vis absorption and magnetic measurements. The adsorptive removal of Congo red using the binary system was performed under various experimental conditions to examine the effects of contact time, solution pH, and initial concentration of Congo red. The results show that the removal abilities and separability of mesoporous TiO₂ adsorbent for Congo red can be significantly improved by modification with γ-Fe₂O₃. The adsorption of Congo red on the γ-Fe₂O₃–TiO₂ reaches the maximum percentage removal of ca. 97 % within 60 min, showing that most of Congo red can be removed in a short time. When the pH of solution is varied from 3.4 to 10.3, the percentage removal of Congo red decreases from ca. 97 to ca. 15 %, showing that the adsorption is strongly dependent on solution pH. The adsorption kinetics of Congo red fit well with pseudo-second-order kinetic model, and the equilibrium data is best described by Langmuir adsorption model. The maximum adsorption capacity of the γ-Fe₂O₃–TiO₂ for Congo red is estimated to be 125.0 mg/g.