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Gold nanoparticles (AuNPs) have been synthesized directly inside liposomes using honey as a reducing agent. The obtained aggregates, named Cassyopea® Gold due to the method used for their preparation, show remarkable properties as reactors and carriers of the investigated AuNPs. A mean size of about 150 nm and negative surface charge of -46 mV were measured for Cassyopea® Gold through dynamic light scattering and zeta potential measurements, respectively. The formation of the investigated gold nanoparticles into Cassyopea® liposomes was spectroscopically confirmed by the presence of their typical absorption band at 516 nm. The catalytic activity of the combined liposome–AuNP nanocomposites was tested via the thermal cis–trans isomerization of resonance-activated 4-methoxyazobenzene (MeO-AB). The kinetic rate constants (kobs) determined at 25 °C in the AuNP aqueous solution and in the Cassyopea® Gold samples were one thousand times higher than the values obtained when performing MeO-AB cis–trans conversion in the presence of pure Cassyopea®. The results reported herein are unprecedented and point to the high versatility of Cassyopea® as a reactor and carrier of metal nanoparticles in chemical, biological, and technological applications. [ABSTRACT FROM AUTHOR]

Although identical in molecular formula and weight, curcumin and cyclocurcumin show remarkable differences in their reactivity. Both are natural compounds isolated from the rhizome of turmeric, the former is involved in the diketo/keto-enol tautomerism through the bis-α,β-unsaturated diketone unit according to the polarity of the solvent, while the latter could react by trans-cis isomerization due to the presence of the α,β-unsaturated dihydropyranone moiety. Even if curcumin is generally considered responsible of the therapeutical properties of Curcuma longa L. due to its high content, cyclocurcumin has attracted great interest over the last several decades for its individual behavior and specific features as a bioactive compound. Cyclocurcumin has a hydrophobic nature characterized by fluorescence emission, solvatochromism, and the tendency to form spherical fluorescent aggregates in aqueous solution. Molecular docking analysis reveals the potentiality of cyclocurcumin as antioxidant, enzyme inhibitor, and antiviral agent. Promising biological activities are observed especially in the treatment of degenerative and cardiovascular diseases. Despite the versatility emerging from the data reported herein, the use of cyclocurcumin seems to remain limited in clinical applications mainly because of its low solubility and bioavailability. [ABSTRACT FROM AUTHOR]

Solute-solvent interactions on the keto-enol tautomerism of 2-nitrocyclohexanone in several organic solvents and room-temperature ionic liquids (RTILs) are analyzed in terms of multiparameter equations. Permittivity and cohesive pressure values of the RTILs, unavailable by direct measurements are derived.

The association between cyclodextrins (CDs) and silver nanoparticles (AgNPs) has been successfully exploited in a large number of applications. Generally, CDs act as stabilizers, however, their reactivity as reducing agents can be directly involved in the synthesis of AgNPs. Herein, the most recent results regarding AgNPs prepared by chemical reduction from native α-, β- and γ-cyclodextrins are reported. The behavior of CDs in host-guest inclusion complexes onto the metal surface, and the effects on the AgNPs properties have also been examined. Unlike β-CD/AgNPs and γ-CD/AgNPs, additional reducing agents were required for the investigated α-CD/AgNPs. [ABSTRACT FROM AUTHOR]

The equilibrium constants for ion pair formation of pyridines are analyzed by spectrophotometric titration with trifluoroacetic acid in different ionic liquids. The basicity order is the same in ionic liquids and in water, whereas pyridine basicity is less sensitive to the substituent effect in ionic liquids than in water.

The solvent effect on the rate of tautomerization of 2-nitrocyclohexanone in several organic solvents has depended on the permittivity of the solvent, but a different behavior is seen on some ionic liquids (ILs). The kinetic results are discussed in terms of the Bronsted equation, which have shown that on passing from molecular solvents to ILs the transition state structure of the enolization reaction has become markedly enolate-like.

The studies about the keto-enol tautomerism of 2-nitrocyclohexanne (2-NCH) which was carried out in aqueous solution under different experimental conditions is presented.

The inductively coupled plasma optical emission spectrometry (ICP‐OES) is a high resolution spectroscopic technique based on the emission intensity at specific wavelengths of a given element within the sample to obtain both qualitative and quantitative information about ions concentration in aqueous solution. The concentration of Ag+ in aqueous solution from negatively charged silver nanoparticles (AgNPs) has been determined by ion selective electrode (ISE) analysis at room temperature. The tested AgNPs solutions have been electrochemically prepared without using any coating agent. The obtained data have been compared to those obtained from the same samples by using ICP‐OES. The good correlation between the two techniques highlights that ISE could be successfully applied as valid alternative to ICP‐OES to determine the silver ion concentration in the investigated conditions. High level of reproducibility, accurate measurements and affordability represent the main advantages of the method described herein. [ABSTRACT FROM AUTHOR]

Multilamellar vesicles (MLVs) from 1-palmitoyl-2-oleoyl- sn - glycero -3-phosphocholine (POPC) were prepared by using the dehydration-rehydration method. The β-cyclodextrin/Ibuprofen inclusion complex (β-CD/Ibu) was formed and solubilised into the aqueous compartments of the investigated vesicles. The resulting POPC MLVs entrapping β-CD/Ibu complex were essentially homogeneous in shape as demonstrated by Transmission Electron Microscopy (TEM). The liposomal stability was determined at 37.0 ± 0.1 °C by following the outflux rate of 5(6)-carboxyfluorescein (CF) at pH 7.40, while the membrane microviscosity was estimated by the ratio of the fluorescence intensities of pyrene in excimer and monomer state. The results presented herein confirm that interactions between POPC and β-CD occur and suggest that associations between POPC and Ibuprofen are also involved in the properties of the investigated liposomes. [ABSTRACT FROM AUTHOR]

Monovarietal virgin olive oils (VOOs) are very effective to study relationships among sensory attributes, the compounds responsible for flavour, and factors affecting them. The stimulation of the human sensory receptors by volatile and non-volatile compounds present in monovarietal virgin olive oils gives rise to the sensory attributes that describe their peculiar delicate and fragrant flavours. The formation of these compounds is briefly illustrated and the influence of the agronomic and technological factors that affect their concentrations in the oil is examined. The relationships between compounds responsible for the olive oil flavour and sensory attributes are discussed. Several approaches for the varietal differentiation of monovarietal virgin olive oils are also overviewed. [ABSTRACT FROM AUTHOR]

BMIM PF6 (1-butyl-3-methylimidazolium hexafluorophosphate) and BMIM Tf2N (1-butyl-3-methylimidazolium bis(trifluoromethylsulfonyl)imide) are two conventional room-temperature ionic liquids widely employed and investigated as reaction media. Despite the presence of the same imidazolium ring in their structure they are different in many chemical and physical properties due to the nature of the anions. The thermal cis-trans isomerization of an electronically activated azobenzene have been used as reaction model to compare the behavior of PF6- and Tf2N-. Rotation is the mechanism by which the investigated azobenzene is converted into the trans isomer spontaneously in the dark both in BMIM PF6 and in BMIM Tf2N. The kinetic rate constants of the process have been determined at different temperatures and the activation energies of the reaction have been calculated according to the Arrhenius and Eyring equations. The results presented herein highlight different solute-solvent interactions involving the PF6- and Tf2N- anions during the cis-trans isomerization. [ABSTRACT FROM AUTHOR]

A series of nanomolar phosphonate matrix metalloproteinase (MPP) inhibitors was tested for inhibitory activity against a panel of selected human carbonic anhydrase (CA, EC 4.2.1.1) isozymes, covering the cancer-associated CA IX and XII. None of the reported sulfonyl and sulfonylamino-derivatives sensitively affected the catalytic activity of the cytosolic isoforms CA I and II, which are considered off-target isoforms in view of their physiological role. The most active inhibitors were in the series of chiralN-(sulfonyl)phosphovaline derivatives, which showed good to excellent inhibitory activity over target CAs, with compound15presenting the best isoform-selectivity toward CA IX. We suggest here that the phosphonates have the potential as dual inhibitors of MMPs and CAs, both involved in tumor formation, invasion and metastasis. [ABSTRACT FROM PUBLISHER]

Dispersions of single-walled carbon nanotubes (SWNTs) have been prepared by using the room-temperature ionic liquid [BMIM][BF4] (1-butyl-3-methylimidazolium tetrafluoroborate), the triblock copolymer Pluronic L121 [poly(ethylene oxide)5-poly(propylene oxide)68-poly(ethylene oxide)5] and the non-ionic surfactant Triton X-100 (TX100) in the pure state. The size of the SWNTs aggregates and the dispersion degree in the three viscous systems depend on the sonication time, as highlighted by UV/Vis/NIR spectroscopy and optical microscopy analysis. A nonlinear increase in conductivity can be observed as a function of the SWNTs loading, as suggested by electrochemical impedance spectroscopy. The generation of a three-dimensional network of SWNTs showing a viscoelastic gel-like behavior above a critical percolation concentration has been found at 25 °C in all the investigated systems by oscillatory rheology measurements. [ABSTRACT FROM AUTHOR]

The effects of a para substituent, as the electron-donating -OCH3 and -OtBu groups and the electron-withdrawing -Br and -F atoms, on azobenzene isomerization have been investigated in a series of imidazolium ionic liquids (BMIM PF6, BMIM BF4, BMIM Tf2N, EMIM Tf2N, BM2IM Tf2N, and HMIM Tf2N). The thermal cis-trans conversion tends to be improved in the presence of the substituent, as pointed out by the first-order rate constants measured at 25 °C. Both the rotation and the inversion mechanisms occur in BMIM Tf2N, EMIM Tf2N, and HMIM Tf2N, as highlighted by typical V-shape Hammett plots, but only rotation takes place in BMIM PF6, BMIM BF4, and BM2IM Tf2N. The possible interactions between the cation and the anion of the solvent and both the isomers of the azobenzene derivatives have been studied by small-wide-angle X-ray scattering (SWAXS). The calculated cis population in the photostationary state and the hardness parameter η of the trans isomer show that azobenzene and F-azobenzene are the less reactive molecules for the trans-cis conversion in all the investigated ionic liquids. [ABSTRACT FROM AUTHOR]

Abstract: Three crown ether derivatives, 1,2-O-dioleoyl-3-O-{2-[(12-crown-4)methoxy]ethyl}-sn-glycerol (12C4L), 1,2-O-dioleoyl-3-O-{2-[(15-crown-5)methoxy]ethyl}-sn-glycerol (15C5L) and 2,3-naphtho-15-crown-5 (NAP5), have been incorporated into 1-palmitoyl-2-oleoyl-phosphatydilcholine (POPC) liposomes. The size of the crown ether and the lipophilic moiety of 12C4L, 15C5L and NAP5 influence the stability and the properties of the extruded POPC liposomes determined at 25°C in buffered aqueous solution at pH7.4. The investigated liposomes are zwitterionic for POPC headgroups but can be turned into cationic aggregates in the presence of divalent cations. The capability of these systems to complex DNA has been demonstrated by SAXS experiments. [Copyright &y& Elsevier]

Abstract: A Zn–salophen complex has been incorporated into POPC large unilamellar liposomes (LUV) obtained in phosphate buffer at pH 7.4. Fluorescence optical microscopy and anisotropy measurements show that the complex is located at the liposomal surface, close to the polar headgroups. The interaction of the POPC phosphate group with Zn2+ slowly leads to demetallation of the complex. The process follows first order kinetics and rate constants have been measured fluorimetrically in pure water and in buffered aqueous solution. The coordination of the phosphate group of monomeric POPC with salophen zinc also occurs in chloroform as detected by ESI-MS measurements. The effect of the Zn–salophen complex on the stability of POPC LUV has been evaluated at 25°C by measuring the rate of release of entrapped 5(6)-carboxyfluorescein (CF) in the presence and in the absence of Triton X-100 as the perturbing agent. It turns out that the inclusion of the complex significantly increases the stability of POPC LUV. [Copyright &y& Elsevier]

The keto--enol tautomerism of some cyclic 2-nitroalkanones was studied in cyclohexane. Keto--enol equilibrium constants, KT, at 25 °C were obtained from ¹H NMR spectra. The relative enol content for the investigated ketones as a function of ring size decreases in the order 6 > 7 > 11 > 12 > 15. This trend apparently is different from that observed in water. Density functional theory (DFT) calculations have been performed to rationalize the effects of ring size and of the solvent on tautomerism. The acidity constants, KaKH, for the different keto tautomers were measured spectrophotometrically at 25 °C in buffered aqueous solutions. No simple correlations between KaKH and ring size was observed, and this is in agreement with a DFT analysis performed on the same compounds. [ABSTRACT FROM AUTHOR]

Abstract: The cationic large unilamellar mixed liposomes from 1-palmitoyl-2-oleoyl-phosphatidylcholine (POPC) and didodecyldimethylammonium bromide (DDAB) or dioctadecyldimethylammonium bromide (DODAB) were prepared. The influence of the addition of Triton X-100 (TX-100) or octaethylene glycol mono-n-dodecylether (C12E8) on the membrane integrity was investigated turbidimetrically. The stability of the liposomal systems was estimated by monitoring fluorimetrically at 25°C the rate of spontaneous and surfactant-induced release of entrapped 5(6)-carboxyfluorescein (CF). In order to evaluate the interaction of the cationic DODAB guest with the host POPC membrane, the main phase transition temperatures (T m) were determined by electron paramagnetic resonance spectroscopy (EPR). All the results obtained show that the presence of DODAB and DDAB stabilizes the POPC liposomes. The extent of stabilization depends on the concentration and nature of the cationic guest. [Copyright &y& Elsevier]

The effect of entrapped β-cyclodextrin (β-CD) on the stability of multilamellar vesicles (MLVs) of 1-palmitoyl-2-oleoyl- sn-glycero-3-phosphocholine (POPC), prepared by the dehydration-rehydration method, was studied by monitoring the release of 5(6)-carboxyfluorescein encapsulated into the liposomes. Different hydrophobic guests, such as Fullerene C60, have been incorporated into the POPC bilayer in order to modify the membrane composition. The kinetic results as well as ESI-MS measurements evidenced that the destabilizing activity of β-CD is due to the formation of β-CD inclusion complexes and the consequent removal of selected bilayer constituents from the liposomal membrane. Hence, when β-CD was added to the liposomes in the form of a strong, water-soluble 2:1 β-CD/C60 inclusion complex, such a destabilizing effect was not observed. However, the same β-CD/C60 inclusion complex does not form as a result of C60 extraction from the bilayer. This may be attributed either to the overwhelming concentration of POPC with respect to C60 and/or to the fact that C60 is largely aggregated in the bilayer. Turbidimetric and fluorimetric determinations of lamellarity and entrapped volume of the studied MLVs provided further evidence of the alteration of the liposomal bilayer as a consequence of the addition of β-CD and/or the presence of the studied guests. [ABSTRACT FROM AUTHOR]

The aim of this work was to deeply investigate the structure and properties of electrochemically synthesized silver nanoparticles (AgNPs) through high-resolution techniques such as transmission electron microscopy (TEM), scanning electron microscopy (SEM), Zeta Potential measurements, and matrix-assisted laser desorption/ionization time of flight mass spectrometry (MALDI-TOF-MS). Strong brightness, tendency to generate nanoclusters containing an odd number of atoms, and absence of the free silver ions in solution were observed. The research also highlighted that the chemical and physical properties of the AgNPs seemed to be related to their peculiar oxidative state as suggested by X-ray photoelectron spectroscopy (XPS) and X-ray powder diffraction (XRPD) analyses. Finally, the MTT assay tested the low cytotoxicity of the investigated AgNPs. [ABSTRACT FROM AUTHOR]

BMIM PF₆ (1-butyl-3-methylimidazolium hexafluorophosphate) and BMIM Tf₂N (1-butyl-3-methylimidazolium bis(trifluoromethylsulfonyl)imide) are two conventional room-temperature ionic liquids widely employed and investigated as reaction media. Despite the presence of the same imidazolium ring in their structure they are different in many chemical and physical properties due to the nature of the anions. The thermal cis-trans isomerization of an electronically activated azobenzene have been used as reaction model to compare the behavior of PF₆ - and Tf₂N - . Rotation is the mechanism by which the investigated azobenzene is converted into the trans isomer spontaneously in the dark both in BMIM PF₆ and in BMIM Tf₂N. The kinetic rate constants of the process have been determined at different temperatures and the activation energies of the reaction have been calculated according to the Arrhenius and Eyring equations. The results presented herein highlight different solute-solvent interactions involving the PF₆ - and Tf₂N - anions during the cis-trans isomerization., Competing Interests: The authors declare no conflict of interest.

Dispersions of single-walled carbon nanotubes (SWNTs) have been prepared by using the room-temperature ionic liquid [BMIM][BF4 ] (1-butyl-3-methylimidazolium tetrafluoroborate), the triblock copolymer Pluronic L121 [poly(ethylene oxide)5 -poly(propylene oxide)68 -poly(ethylene oxide)5 ] and the non-ionic surfactant Triton X-100 (TX100) in the pure state. The size of the SWNTs aggregates and the dispersion degree in the three viscous systems depend on the sonication time, as highlighted by UV/Vis/NIR spectroscopy and optical microscopy analysis. A nonlinear increase in conductivity can be observed as a function of the SWNTs loading, as suggested by electrochemical impedance spectroscopy. The generation of a three-dimensional network of SWNTs showing a viscoelastic gel-like behavior above a critical percolation concentration has been found at 25 °C in all the investigated systems by oscillatory rheology measurements., (© 2016 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.)

The self-assembly of a series of triblock co polymers Pluronics (P85, P105 and L121) has been investigated in some ionic liquids (BMIMBF4, BMIMPF6 and BMIMTf2N) by using Near-Infrared spectroscopy. The formation of supramolecular s tructures has been confirmed by optical microscopy. The solvation degree and the aggregation behaviour of P85, P105 and L121 depend on the interactions between the imidazolium ring of the ionic liquid and the hydrophilic moiety of the copolymer. Fluorescent vesicles can be observed after the incorporation of Nile Red into the polymeric bilayer of L121 or by linking fluorescein isothiocyanate to the copolymer structure.

Surfactant-liposome interactions have been previously studied through different methods and techniques. We present here a classical physical chemistry study on liposome solutions added to destabilizing agents at concentrations well above the solubilization concentration, which enable us to draw useful and interesting conclusions about the mechanism of surfactant-induced liposomal breakdown by simply exploiting the kinetics and the reaction order of the liposomal content release. In such excess of surfactant, the mechanism of surfactant-induced rupture of the liposomes has been demonstrated to be different from that proposed for low surfactant concentrations. Thus, depending on the surfactant concentration, two prevailing processes have been evidenced: (i) a cooperative mechanism that implies the assembly of a critical number of surfactant molecules to trigger the formation of a channel and therefore the release of the liposomal content and (ii) a mechanism driven by direct interaction of the surfactant molecules with the lipids that causes the complete solubilization of the liposomes. The former mechanism occurs at low surfactant concentrations, whereas the latter occurs at higher concentrations and above the CMC of the surfactants. The effect of different guests embedded into the liposomal bilayer on the mechanism of surfactant-induced liposomal breakdown has been compared by using the second-order rate constants measured for the liposome breakdown process.

The effect of entrapped beta-cyclodextrin (beta-CD) on the stability of multilamellar vesicles (MLVs) of 1-palmitoyl-2-oleoyl-sn-glycero-3-phosphocholine (POPC), prepared by the dehydration-rehydration method, was studied by monitoring the release of 5(6)-carboxyfluorescein encapsulated into the liposomes. Different hydrophobic guests, such as Fullerene C(60), have been incorporated into the POPC bilayer in order to modify the membrane composition. The kinetic results as well as ESI-MS measurements evidenced that the destabilizing activity of beta-CD is due to the formation of beta-CD inclusion complexes and the consequent removal of selected bilayer constituents from the liposomal membrane. Hence, when beta-CD was added to the liposomes in the form of a strong, water-soluble 2:1 beta-CD/C(60) inclusion complex, such a destabilizing effect was not observed. However, the same beta-CD/C(60) inclusion complex does not form as a result of C(60) extraction from the bilayer. This may be attributed either to the overwhelming concentration of POPC with respect to C(60) and/or to the fact that C(60) is largely aggregated in the bilayer. Turbidimetric and fluorimetric determinations of lamellarity and entrapped volume of the studied MLVs provided further evidence of the alteration of the liposomal bilayer as a consequence of the addition of beta-CD and/or the presence of the studied guests.

The effect of microwave (MW) irradiation and ionic liquids (IL) on the cycloaddition of azomethine ylides to [60]fullerene has been investigated by screening the reaction protocol with regard to the IL medium composition, the applied MW power, and the simultaneous cooling of the system. [60]Fullerene conversion up to 98 % is achieved in 2-10 min, by using a 1:3 mixture of the IL 1-methyl-3-n-octyl imidazolium tetrafluoroborate ([omim]BF(4)) and o-dichlorobenzene, and an applied power as low as 12 W. The mono- versus poly-addition selectivity to [60]fullerene can be tuned as a function of fullerene concentration. The reaction scope includes aliphatic, aromatic, and fluorous-tagged (FT) derivatives. MW irradiation of IL-structured bucky gels is instrumental for the functionalization of single-walled carbon nanotubes (SWNTs), yielding group coverages of up to one functional group per 60 carbon atoms of the SWNT network. An improved performance is obtained in low viscosity bucky gels, in the order [bmim]BF(4)> [omim]BF(4)> [hvim]TF(2)N (bmim=1-methyl-3-n-butyl imidazolium; hvim=1-vinyl-3-n-hexadecyl imidazolium). With this protocol, the introduction of fluorous-tagged pyrrolidine moieties onto the SWNT surface (1/108 functional coverage) yields novel FT-CNS (carbon nanostructures) with high affinity for fluorinated phases.

The rates of tautomerization of 2-nitrocyclohexanone (2-NCH) have been measured spectrophotometrically at 25.0 +/- 0.1 degrees C in several organic aprotic solvents and their binary mixtures. In cyclohexane the reaction is effectively catalyzed by bases and inhibited by acids while the so-called "spontaneous reaction" appears essentially due to autocatalysis. Apparent second order rate constants (k(app)(B)) for the reaction catalyzed by triethylamine (TEA) and pyridine (Pyr) have been obtained. From the experimental k(app)(B) values rate constants for the enolization (k(1)(B)) and ketonization (k(-1)(B)) reactions have been calculated. A Kamlet-Taft type linear solvation energy relationship (LSER) adequately accounts for the observed solvent effects. Activation parameters for both reactions show that solvent effects are mainly entropic in origin and that there is a shift of the transition state from a ketone-like to an enol-like structure on passing from less to more polar solvents.