Search

Electrically conductive fabrics are achieved by functionalizing with treatments such as graphene, however, these change conventional fabric properties and the treatments are typically not durable. Encapsulation may provide a solution for this, and the present work aims to address these challenges. Next-to-skin wool and cotton knit fabrics functionalized using graphene ink were encapsulated with three poly(dimethylsiloxane)-based products. Properties known to be critical in a next-to-skin application were investigated (fabric structure, moisture transfer, electrical conductivity, exposure to transient ambient conditions, wash, abrasion, and storage). Wool and cotton fabrics performed similarly. Electrical conductivity was conferred with the graphene treatment but decreased with encapsulation. Wetting and high humidity/low temperature resulted in an increase in electrical conductivity, while decreases in electrical conductivity were evident with wash, abrasion, and storage. Each encapsulant mitigated effects of exposures but these effects differed slightly. Moisture transfer changed with graphene and encapsulants. As key performance properties of the wool and cotton fabrics following treatment with graphene and an encapsulant differed from their initial state, use as a patch integrated as part of an upper body apparel item would be acceptable.

Science disengagement amongst school children remains a global challenge, leading to calls for more scientists to engage with the public. Here the authors discuss how a voluntary, flexible program can enhance graduate attributes in addition to addressing barriers to public engagement.

Nonporous coordination polymers (CPs) constructed from flexible bridging ligands have seldom been utilized in practical applications, owing to limited solubility and/or stability in most solvents. Here we have produced nanocrystal coordination polymers (NCPs) with identical crystalline structure to their macroscale counterparts, high solvent dispersibility, and large effective surface area for catalytic application. A microemulsion system has been developed for the mild synthesis of the ZnII- and CuII-NCPs, resulting in control over the size, morphology, and reactivity. Both ZnII- and CuII-NCPs demonstrated high catalytic activity in a ring opening reaction of cyclohexene oxide with aniline; furthermore, reduced Cu-NCPs were employed as efficient, reusable catalysts for an azide–alkyne cycloaddition “click” reaction in the nonpolar solvent heptane. In contrast, all macroscale CP equivalents, prepared by conventional methods, were catalytically inactive.

A series of electronically diverse imines were found to readily react with various donor-acceptor cyclopropyl acid chlorides, with complete regioselectivity, to form 1,3-oxazin-4-ones in moderate yields (25-48% over two steps). Select oxazinones underwent a base induced rearrangement to afford the corresponding cycloheptene-fused oxazinones in good yields (up to 70%).

The incorporation of an imidazoline (IDZ) based switchable surfactant into the lipid membrane of a liposome produces a system that can be triggered to release its solute upon pH change. However, unlike traditional pH-triggered controlled release systems, IDZ–liposomes are capable of undergoing multiple triggering events, resulting in solute release in a pulsatile manner. Furthermore near-total release can be achieved incrementally with temporal control. A mechanism for this reversible behaviour is also proposed, and dependence on the physical properties of the surfactant is discussed.

A series of ditopic ω-di(2-pyridylmethyl)amine carboxylic acid ligands incorporating a range of n-alkyl linkers (CnCOOH, n = 3–5, 7, 10 and 11) have been synthesised. Solution phase studies showed a 1 : 1 coordination stoichiometry between the ligands and M(ClO4)2·6H2O (M = ZnII or CuII) in all cases. The ZnII and CuII complexes were subsequently crystallised by liquid–liquid diffusion and the solid-state structures investigated by X-ray crystallography. The crystal structures obtained are entirely consistent with the 1 : 1 metal–ligand ratio of the solution-phase adducts. However, the coordination geometries and complex topologies are dependent on the alkyl chain length of the ligand CnCOOH. The ZnII and CuII complexes of the short alkyl chain ligands (n ≤ 5) exhibit 1D coordination polymeric structures with somewhat different conformations for {[Zn(C3COO)(H2O)](ClO4)·3.5H2O}n (1), {[Zn(C4COO)(H2O)]4(ClO4)4·1.5H2O}n (2), {[Zn(C5COO)(H2O)](ClO4)}n (3), {[Cu(C3COO)](ClO4)·MeOH}n (4), {[Cu(C4COO)(H2O)]2(ClO4)2·2H2O}n (5) and {[Cu(C5COO)(H2O)](ClO4)·2H2O}n (6). In contrast, the ligands with longer alkyl chains (n ≥ 7) participate in Zn2L2 metallomacrocyclic structures {[Zn(C7COO)(H2O)](ClO4)}2 (7), [Zn2(C10COO)2(H2O)2](ClO4)2·2H2O·MeOH (8) and {[Zn2(C11COO)2(H2O)2][Zn2(C11COO)2](ClO4)4·H2O}n (9). The formation of metallomacrocycles instead of the 1D coordination polymers is a persistent trend and, with identical crystal growth conditions and a non-coordinating anion employed, appears to be an effect of the longer alkyl chain.

1,3-Oxazinen-4-ones are medicinally important scaffolds which have traditionally been accessed using a hetero-Diels-Alder approach or more recently using a cobalt-catalyzed three-component cycloaddition. Herein we report a novel strategy to access this scaffold which allows for the rapid and high yielding synthesis of 1,3-oxazinen-4-ones under ambient temperature and pressures with improved substrate scope.

The unique surface plasmon resonance of hollow gold nanoshells can be used to achieve drug release from liposomes upon laser stimulation, and adapted to mimic the intricate dynamics of neurotransmission ex vivo in brain preparations. However, to induce a physiological response in vivo requires the degree of temporal precision afforded by laser stimulation, but with a greater depth of penetration through tissue. Here we report that the attachment of hollow gold nanoshells to the surface of robust liposomes results in a construct that is highly sensitive to ultrasonic stimulation. The resulting construct can be remotely triggered by low intensity, therapeutic ultrasound. To our knowledge, this is the first example of nanoparticle-liposome system that can be activated by both laser and acoustic stimulation. The system is capable of encapsulating the neurochemical dopamine, and repeatedly releasing small amounts on-demand in a circulating environment, allowing for precise spatiotemporal control over the release profile. Nanoscale materials hold promising applications for controlled release of bioactive compounds. Here hollow gold nanoshells tethered to liposomes allows the controlled release of encapsulated neurochemicals by acoustic or laser stimulation

Incorporation of an amidine-based switchable surfactant into the lipid membrane of a liposome produces a system that is capable of triggered release upon in situ exposure to CO2. The amount of liposomal contents released is dependent on the concentration of switchable surfactant incorporated. A mechanism of the release is proposed.

A series of electronically diverse imines were found to readily react with various donor–acceptor cyclopropyl acid chlorides, with complete regioselectivity, to form 1,3-oxazin-4-ones in moderate yields (25–48% over two steps). Select oxazinones underwent a base induced rearrangement to afford the corresponding cycloheptene-fused oxazinones in good yields (up to 70%).

Two novel series of hydroxymethyl group-appended quaternary nitrogen surfactants (QNSs) based on the aliphatic N-alkyl-trimethylammonium and aromatic N-alkylpyridinium head groups were synthesized from the appropriate nitrogen head group precursor and 1-bromoalkane. The QNSs were characterized using 1H and 13C nuclear magnetic resonance and infrared spectroscopy, and their purity confirmed using elemental analysis. The solution behavior of the QNSs was investigated by conductivity, assessing both the aggregation concentration as well as the amount of counter-ion dissociation. The results showed a general decrease in the aggregation concentration for the compounds with the hydroxymethyl addition, where the pyridinium compounds were more affected than the ammonium QNSs. In contrast, the extent of counter-ion dissociation (α) from the aggregate was slightly increased for the ammonium compounds but that of the pyridinium compounds was not generally affected by the structural modification.

The chemical species involved in the adhesion of blue mussels ( Mytilus galloprovincialis) and greenshell mussels ( Perna canaliculus) to surfaces has been investigated using in situ attenuated total reflection infrared (ATR-IR) spectroscopy. Mussel spat ranging in size from 0.5 to 25 mm were placed in a flow cell containing a ZnSe multiple internal reflection prism and supplied with temperature-controlled seawater. Distinctively different absorption spectra were obtained when the mussels were predominantly moving across the surface or forming permanent bonds. With limited movement, the absorption spectrum was characteristic of protein with peaks near 1647 cm−1(amide I), 1543 cm−1(amide II), and 1235 cm−1(amide III). When the mussels were observed to be moving across the surface of the ATR-IR crystal there was a strong broad absorption maximum around 1200–900 cm−1(carbohydrate polymers), presumably due to the secretion of a weakly acidic mucopolysaccharide. Distinct differences in the spectra obtained from the adhesive secretions of blue or greenshell mussels were not observed. The data presented is the first reported use of IR spectroscopy to obtain in situ, real-time, chemical data on the interactions between invertebrates and substrates immersed in sea water.

We use a mathematical model to describe the delivery of a drug to a specific region of the brain. The drug is carried by liposomes that can release their cargo by application of focused ultrasound (US). Thereupon, the drug is absorbed through the endothelial cells that line the brain capillaries and form the physiologically important blood-brain barrier (BBB). We present a compartmental model of a capillary that is able to capture the complex binding and transport processes the drug undergoes in the blood plasma and at the BBB. We apply this model to the delivery of levodopa (L-dopa, used to treat Parkinson's disease) and doxorubicin (an anticancer agent). The goal is to optimize the delivery of drug while at the same time minimizing possible side effects of the US.

Starting from 1-benzoyl or 1-acetylcyclopropane-1-carboxylic acid and a range of imines, the title compounds are synthesized in a high-yielding operationally simple and rapid manner.

Reaction of (S)-2-chloro-3-phenylpropanoic acid derivatives with NBS gave the corresponding 3-bromo-2-chloro derivatives with a preference for the formation of the (2R,3S) isomers over the (2R,3R) isomers. The stereoselectivity was affected by the nature of the carboxylic acid derivative. Reaction of ester derivatives was highly stereoselective while the reaction of amide derivatives showed varied stereoselectivity which depended on the nature of the amide. Theoretical studies at UHF/3-21G* level showed that the intermediate benzylic radical of the methyl ester, the methyl amide and the diisopropyl amide derivatives had different energy profiles with respect to rotation of the C2–C3 bond. The different stereoselectivity observed from reaction of the various acid derivatives could be attributed, at least in part, to different distribution of conformers of the radical intermediate.

Two progressive series of molecules with two polyhydroxybenzamide substructures were synthesized and tested as potential inhibitors of catechol-O-methyltransferase (COMT). These compounds were designed for the purpose of enhanced enzyme binding with duplicated substructures separated by a linker section of various lengths. Our results show that potency and mode of inhibition observed with the "bifunctional" compounds were a reflection of their bifunctional nature. Furthermore, potency and mode of inhibition were dependent on the length of the linker section. Of the assayed compounds, the optimum linker was found to be diaminopropane. For example, N,N'-1,3-propanediylbis(3,4-dihydroxybenzamide) and N,N'-1,3-propanediylbis(3,4,5-trihydroxybenzamide) demonstrated strong inhibitory action against COMT, with apparent Ki values of 0.3 and 6.0 microM, respectively.

The stereochemistry at position 2 of the title compound, C 14 H 17 BrO 4 , has been confirmed as S.

Reaction of (S)-2-chloro-3-phenylpropanoic acid derivatives with NBS gave the corresponding 3-bromo-2-chloro derivatives with a preference for the formation of the (2R,3S) isomers over the (2R,3R) isomers. The stereoselectivity was affected by the nature of the carboxylic acid derivative. Reaction of ester derivatives was highly stereoselective while the reaction of amide derivatives showed varied stereoselectivity which depended on the nature of the amide. Theoretical studies at UHF/3-21G* level showed that the intermediate benzylic radical of the methyl ester, the methyl amide and the diisopropyl amide derivatives had different energy profiles with respect to rotation of the C2–C3 bond. The different stereoselectivity observed from reaction of the various acid derivatives could be attributed, at least in part, to different distribution of conformers of the radical intermediate.

An enantioselective 1,2-chlorine atom migration was observed in the tributyltin hydride reduction of various dihalogenated dihydrocinnamic acid derivatives. It is proposed that the reduction involves the formation of a chlorine-bridged radical intermediate, followed by hydrogen atom transfer to either the beta- or the alpha-carbon. The product distribution is affected by electron-withdrawing groups in that hydrogen atom transfer to the proximate carbon is favored. Presumably, this is due to the transition state of the hydrogen delivery step being electron rich, due to the relatively electropositive tin radical. These results demonstrate a 1,2-chlorine atom migration reaction governed by polar effects.

Proteins from eucaryotic cells which have a carboxyl-terminal CAAX motif are posttranslationally modified by isoprenylation. The pathway involves the linkage of an all-trans-farnesyl (C15) or an all-trans-geranylgeranyl (C20) moiety to the cysteine residue followed by proteolysis which generates the modified cysteine as the carboxyl-terminal residue. Carboxylmethylation of the modified cysteine residue completes the pathway. This latter methylation reaction is the only potentially reversible reaction in the pathway and thus of possible regulatory significance. A specific esterase is required to reverse the methylation. It is demonstrated here that simple isoprenylated cysteine derivatives, such as N-acetyl-S-farnesyl-L-cysteine methyl ester (L-AFCM) and N-acetyl-S-geranylgeranyl-L-cysteine methyl ester (L-AGGCM), are substrates for a rod outer segment (ROS) membrane esterase activity. The KM and Vmax values for L-AFCM and L-AGGCM are 186 microM and 2.2 nmol mg-1 min-1 and 435 microM and 4.8 nmol mg-1 min-1, respectively. The enzyme(s) is stereoselective rather than stereospecific because D-AFCM is enzymatically hydrolyzed with KM and Vmax values of 157 microM and 0.46 nmol mg-1 min-1, respectively. The enzyme(s) does not process N-acetyl-L-cysteine methyl ester, demonstrating that the isoprenyl moiety is required for substrate activity. Ebelactone B is a potent mechanism-based inactivator of the enzyme with a KI = 42 microM and a kinh = 3.7 x 10(-3) s-1. Importantly, L-AFCM, L-AGGCM, and ebelactone B all inhibit the demethylation of the endogenous ROS substrates, showing that the same enzymatic activity is involved in the processing of the synthetic and physiological substrates.

Structure-activity studies were performed on the retinal rod outer segment isoprenylated protein methyltransferase that transfers a methyl group from S-adenosylmethionine (AdoMet) to the carboxyl group of isoprenylated (farnesylated or geranylgeranylated) cysteine residues. This methyltransferase enzyme has been shown to methylate N-acetyl-S-farnesyl-L-cysteine (L-AFC, 1) and S-(farnesyl-3-thio)propionic acid (FTP, 2). It is shown here that the enzyme does not enzymatically process D-AFC (8), although D-AFC (8) is a mixed-type inhibitor of the enzyme

The free-radical reactions of a range of amino acid derivatives with N-bromosuccinimide are described. The products and relative rates of these reactions indicate that the α-position of an N-phthaloyl-substituted α-amino acid derivative is much less reactive than that of a corresponding N-acyl amino acid derivative toward hydrogen atom transfer. This is attributed to the proactive effects of acylamino and carboxyl substituents, in contrast to the counteractive effects of phthalimido and carboxyl groups. The reactions exemplify procedures for the regiocontrolled functionalization of amino acid and peptide derivatives. © 1991, American Chemical Society. All rights reserved.

Retinal transducin was previously shown to be farnesylated on its gamma subunit. This farnesylation reaction on a cysteine residue near the carboxyl terminus is followed by peptidase cleavage at the cysteine. Thus the modified cysteine becomes the carboxyl terminus. It is shown here that the free carboxyl group can be methylated by an S-adenosyl-L-methionine-dependent methyltransferase associated with the rod outer segment membranes. This process can be inhibited by S-adenosyl-L-homocysteine and sinefungin. Moreover, synthetic N-acetyl-S-farnesyl-L-cysteine, but not N-acetyl-L-cysteine, is a substrate for the enzyme. Rapid demethylation of N-acetyl-S-farnesyl-L-cysteine methyl ester can be observed in the membranes. Transducin is also enzymatically demethylated by the rod outer segment membranes. Moreover, the 23- to 29-kDa small G proteins are methylated and demethylated in this system. These data suggest that methylation/demethylation may play a regulatory role in visual signal transduction.

Bifunctional compounds were tested in vitro as potential inhibitors of pig liver catechol-O-methyltransferase (COMT) with respect to the catechol substrate 4-[(3,4-dihydroxyphenyl)azo]benzenesulfonate. The bifunctional compounds were a composite of either two nitrocatechols or one nitrocatechol and one phenol, linked by amide bonds to a spacer unit comprising two to five methylene groups. The unsymmetrical compounds N-[2-(4-hydroxybenzoylamine)ethyl]-3,4-dihydroxy-5-nitrobenzamide], N-[3-(4-hydroxybenzoyl-amine)propyl]-3,4-dihydroxy-5-nitrobenzamide] and N-[5-(4-hydroxybenzoylamine)pentyl]-3,4-dihydroxy-5-nitrobenzamide] demonstrated strong inhibitory action against COMT with K(i) values in the 100 nM range. In comparison, the monofunctional nitrocatechol analogues of these compounds had K(i) values that were significantly higher.

The title compound, C 17 H 14 O 5 , was obtained as a byproduct from a procedure to regioselectively hydroxylate homochiral acid derivatives. Structural analysis confirmed its identity and showed it to be achiral.

A series of catechol diazo dyes were synthesized and tested as substrates for the enzyme catechol-O-methyltransferase (COMT) with the aim of developing a sensitive HPLC assay method using visible wavelength light detection. A method was developed which allowed for the determination of the two regioisomeric methylated products of the COMT catalyzed reaction of 4-[(3,4-dihydroxyphenyl)azo]benzenesulfonate with S-adenosylmethionine (AdoMet). Separation of the assay components was achieved by reverse phase chromatography using an isocratic mobile phase. No pre-preparation of the assay samples was required.

Existing nanoscale chemical delivery systems target diseased cells over long, sustained periods of time, typically through one-time, destructive triggering. Future directions lie in the development of fast and robust techniques capable of reproducing the pulsatile chemical activity of living organisms, thereby allowing us to mimic biofunctionality. Here, we demonstrate that by applying programmed femtosecond laser pulses to robust, nanoscale liposome structures containing dopamine, we achieve sub-second, controlled release of dopamine – a key neurotransmitter of the central nervous system – thereby replicating its release profile in the brain. The fast delivery system provides a powerful new interface with neural circuits, and to the larger range of biological functions that operate on this short timescale.

The first structural analysis of a 1,2-disubstituted adamantane, (±)-adamantane-1,2-diyl diacetate, C14H20O4, is reported. The molecules pack in columns which are held together by inter- and intracolumn C—H⋯O interactions.

Structural analysis of trans-3-bromo-2-chloro­indan-1-one, C9H6BrClO, confirms the relative stereochemistry of the Cl and Br atoms.

Environmental contextOseltamivir (Tamiflu) is widely used to prevent and treat influenza but conventional wastewater processes involving sedimentation and biotic oxidation do not appear to significantly remove it from sewage, leading to its discharge into the environment. A range of advanced oxidation processes (AOPs) involving photolysis of aqueous solutions of oseltamivir with UV alone, UV/H2O2 and UV/H2O2/FeII is demonstrated to lead to photodegradation of oseltamivir to products with no ecotoxicity observed. These AOPs may therefore offer potentially environmentally friendly sewage water treatment options. AbstractAqueous solutions of the antiviral drug oseltamivir phosphate (OSP, Tamiflu, (3R,4R,5S)-ethyl 4-acetamido-5-amino-3-(pentan-3-yloxy)cyclohex-1-enecarboxylate) were degraded using advanced oxidation processes (AOPs) involving photodegradation with UV alone, UV/H2O2 and UV/H2O2/FeII (photo-Fenton reaction). The photodecay of the parent OSP in all three cases followed first-order kinetics with respective rate constants of 0.21, 1.56 and 1.75 min–1 at 20°C in pH 7 phosphate-buffered Milli-Q water. The rate of UV/H2O2 photolysis in the presence of 2-methylpropan-2-ol was significantly slower with an approximate first-order rate constant of 0.13 min–1 suggesting the involvement of •OH in the degradation process. NMR spectroscopy, mass spectrometry and high-performance liquid chromatography (HPLC) with UV diode array detection were used to identify the crude photoproduct as the hydroxylated OSP derivative (3S,4R,5S)-ethyl 4-acetamido-5-amino-2-hydroxy-3-(pentan-3-yloxy)cyclohexanecarboxylate that occurs by an unknown mechanism. OSP and this crude photoproduct demonstrated no effect on the survival of Quinquelaophonte sp. over 96 h.

The structural analysis of the title compound, C15H8ClF5O2, confirms the position of the Cl atom at C-3.

Proteins that are post-translationally modified by prenylation can be either farnesylated (C-15) or geranylgeranylated (C-20) by separate prenyltransferase enzymes. Prenylated proteins are also methylated at their C-terminal residue by S-adenosylmethionine-linked methylation. In this paper we show that the methylation of farnesylated and geranyl-geranylated substrates can be accounted for by the presence of a single enzyme. It is demonstrated that the Km and Vmax. values for the retinal rod outer segment methyltransferase, measured with small molecule farnesylated and geranylgeranylated substrates, are identical. These substrates mutually inhibit each other's methylation, with KI values being equal to their Km values. The Km for S-adenosylmethionine was measured to be the same with either farnesylated or geranylgeranylated substrates. Competitive inhibitors of the methyltransferase containing either a geranylgeranyl or a farnesyl group equally block the methylation of synthetic geranylgeranylated and farnesylated substrates of the enzyme. Importantly, these inhibitors are also equipotent at inhibiting the methylation of the physiological substrates of the rod outer segment methyltransferase. These substrates are both farnesylated and geranylgeranylated. One of these substrates had previously been identified as the farnesylated gamma subunit of transducin. Therefore it appears that the same enzymic activity can methylate both farnesylated and geranylgeranylated substrates.

The stereochemistries at positions 2 and 3 of the title compounds, C15H21BrClNO, (I), and C15H12BrClN2O3, (II), have been confirmed by X-ray structural analysis. The halogen atoms adopt an antiperiplanar arrangement in each case.

In the title compound, C19H34N+·Br−·H2O, the dihedral angle between the trans-planar alkyl side chain and the pyridinium ring is 52.73 (7)°. In the crystal structure, O—H...Br, C—H...Br and C—H...O hydrogen bonds form a network, while the hydrophobic alkyl chains interdigitate, forming bilayers.

The stereochemistry at position 2 of the title compound, C 14 H 17 BrO 4 , has been confirmed as S.