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The C1858T variant of the protein tyrosine phosphatase N22 (PTPN22) gene is associated with pathophysiological phenotypes in several autoimmune conditions, namely, Type 1 diabetes and autoimmune thyroiditis. The R620W variant protein, encoded by C1858T, leads to a gain of function mutation with paradoxical reduced T cell activation. We previously exploited a novel personalized immunotherapeutic approach based on siRNA delivered by liposomes (lipoplexes, LiposiRNA) that selectively inhibit variant allele expression. In this manuscript, we functionalize lipoplexes carrying siRNA for variant C1858T with a high affinity ligand of Siglec-10 (Sig10L) coupled to lipids resulting in lipoplexes (LiposiRNA-Sig10L) that enhance delivery to Siglec-10 expressing immunocytes. LiposiRNA-Sig10L lipoplexes more efficiently downregulated variant C1858T PTPN22 mRNA in PBMC of heterozygous patients than LiposiRNA without Sig10L. Following TCR engagement, LiposiRNA-Sig10L more significantly restored IL-2 secretion, known to be paradoxically reduced than in wild type patients, than unfunctionalized LiposiRNA in PBMC of heterozygous T1D patients.

In this work, we present a detailed analysis of the different acceptations and practices of art criticism. This investigation underpins a novel conceptual modelling that extends Cidoc CRM and has been specifically designed to semantically annotate art criticism-related data and documents in order to enhance in this context interoperability and more efficient data retrieval.

The C1858T variant of the protein tyrosine phosphatase N22 (

Though liposome-based drugs are in clinical use, the mechanism of cell internalization of liposomes is yet an object of controversy. The present experimental investigation, carried out on human glioblastoma cells, indicated different internalization routes for two diastereomeric liposomes. Molecular dynamics simulations of the lipid bilayers of the two formulations indicated that the different stereochemistry of a lipid component controls some parameters such as area per lipid molecule and fluidity of lipid membranes, surface potential and water organization at the lipid/water interface, all of which affect the interaction with biomolecules and cell components.

In this chapter we describe: (1) the procedure for the synthesis of four single chain bolaamphiphiles, displaying chains of 12, 16, 20 and 30 methylene units and triphenylphosphonium moieties as headgroups (TPP1-TPP4); (2) the methods used to characterize TPP1-TPP4 spontaneous aggregation in aqueous solution. We illustrate the determination of Krafft point and cac by conductivity measurements and the procedures used to investigate dimensions, morphology, and stability by dynamic and dielectrophoretic laser light scattering, dialysis, transmission electron microscopy, and Raman spectroscopy measurements.

Hypothesis Bolaamphiphiles are characterized by wide polymorphism of their aggregates, due to the connection of the headgroups that renders their investigation very intriguing in several technological applications. Some bolaamphiphiles displaying the triphenylphosphonium motif (TPP-bolaamphiphiles) were previously explored for their ability in crossing the mitochondrial membranes but their colloidal features, which are crucial for the potential development of an effective drug delivery system, were never investigated. Experiments Single chain TPP-bolaamphiphiles, featuring chains of 12, 16, 20 and 30 methylene units, were synthesized and their aggregation features (Krafft point, cac, dimensions, morphology, stability) were investigated by conductivity, dialysis, transmission electron microscopy, Raman spectroscopy, dynamic and dielectrophoretic laser light scattering measurements. Findings All the TPP-bolaamphiphiles spontaneously self-assemble into vesicles, independently of the chain length. The bolaamphipile with the longest chain forms monodispersed vesicles whereas for the other bolaamphiphiles two distinct populations of vesicles are observed. All vesicles are not equilibrium systems, in particular vesicles formed by the bolaamphiphiles featuring 20 and 30 methylene units result notably stable to dilution thanks to both the tightening of molecular packing at increasing chain length and the progressive reduction of the monomer percentage in U-shaped conformation. These features make these TPP-bolaamphiphiles very attractive as minor components for the development of novel mitochondriotropic liposomes.

In this chapter we describe: (1) the procedure for the synthesis of four single chain bolaamphiphiles, displaying chains of 12, 16, 20 and 30 methylene units and triphenylphosphonium moieties as headgroups (TPP1-TPP4); (2) the methods used to characterize TPP1-TPP4 spontaneous aggregation in aqueous solution. We illustrate the determination of Krafft point and cac by conductivity measurements and the procedures used to investigate dimensions, morphology, and stability by dynamic and dielectrophoretic laser light scattering, dialysis, transmission electron microscopy, and Raman spectroscopy measurements.

Autophagy is a mechanism involved in many human diseases and in cancers can have a cytotoxic/cytostatic or protective action, being in the latter case involved in multidrug resistance. Understanding which of these roles autophagy has in cancer is thus fundamental for therapeutical decisions because it permits to optimize the therapeutical approach by activating or inhibiting autophagy according to the progression of the disease. However, a serious drawback of cancer treatment is often the scarce availability of drugs and autophagy modulators at the sites of interest. In the recent years, several nanocarriers have been developed and investigated to improve the solubility, bioavailability, controlled release of therapeutics and increase their cytotoxic effect on cancer cell. Here we have reviewed only liposomes as carriers of chemotherapeutics and autophagy inhibitors because they are the sole nanoparticles that are actually used as drug carriers in oncological clinical settings. In this review after the analysis of the dual role of autophagy, of the main autophagic pathways, and of the role of autophagy in multidrug resistance, we will focus on the most effective liposomal formulations, thus highlighting the great potential of these targeting systems to defeat cancer diseases.

(+)-Usnic acid (UA) is a natural substance that displays pharmacological activity, but it is barely soluble in water, so it was included in liposomes in order to study its properties. First, the effects of phospholipid structure and loading methodology on UA entrapment efficacy were evaluated. Then, the physicochemical and biological properties (UA delivery efficacy to Staphylococcus aureus bacterial cells) of different liposome formulations containing structurally related amphiphiles derived from L-prolinol were fully investigated. Entrapment efficiency of UA with passive loading by incubation was 80-100 molar percentage, which is related to lipophilicity of the drug and to the packing and fluidity of the bilayer. Some of the investigated formulations show the potential of UA in delivery systems (minimum inhibitory concentration of liposomal UA: 8 μg/mL) and even subtle variations of the molecular structure of lipids can significantly affect the liposomes' physicochemical properties and efficiency of drug release.

Identification and quantification of bacteria affecting human life, directly causing diseases and indirectly contaminating natural ecosystems, are mostly carried out by expensive and time-consuming methods. There is the need for rapid and economic ways for detecting bacteria in the environment and in clinics. We propose the use of engineered liposomes for detecting bacteria in drinking water. Our approach exploits cationic liposomes functionalized with a surface potential-sensitive fluorophore, 4-heptadecylumbelliferone (C17-HC). The interaction between liposomes and bacteria involves a change in the surface potential experienced by C17-HC and switches on an optical signal. We investigated, by DLS, zeta-potential and fluorescence experiments, a large number of cationic liposomes formulated with a natural phospholipid 1,2-dipalmitoyl- sn -glycero-3-phosphocholine (DPPC) or 1,2-dioleoyl- sn -glycero-3-phosphocholine (DOPC), C17-HC, and one of three synthetic cationic components, differing from each other for the number of unsaturations on the polar ammonium head, two of which ad hoc synthesized. Then we evaluated the ability of liposomes to produce a fluorescent signal upon interaction with three bacterial strains, Staphylococcus aureus , Escherichia coli and Enterococcus faecalis ; moreover, we analyzed the fluorescent response of each liposome formulation in the presence of the three bacterial strains at the same time, in order to simulate a real scenario. We found that interaction with bacteria triggers an optical signal in six of the evaluated formulations, resulting responsive down to 10 2 CFU/mL of bacteria suspended in pipeline water coming from the water main of Rome (Italy).

5-Fluorouracil (5-FU) is a chemotherapic drug widely employed to treat a wide range of solid tumors. Unfortunately, it has a narrow therapeutic window and the level of its target enzymes in biological fluids of patients can vary considerably. On these premises, a new fluorescent lipid based sensor for the detection of thymidine phosphorylase, one of the target enzymes of 5-FU, was developed, to optimize patient treatment. Both cationic and anionic fluorescent liposomes containing both an amphiphile tail-tagged with a pyrene residue and a 5‐FU derivative were investigated. The effect of the presence of a bulky quencher (the bromine atom) covalently linked to the end of the alkyl chain of the anionic component on the emission signal was also evaluated. The interaction of liposomes with the target enzyme induces the occurrence of a fluorescent signal, at an extent that depends on the formulation, due to the variation of the excimer/monomer ratio. In particular, a promising specific result was obtained upon the interaction of the target enzyme with liposomes formulated with DOPC, the cationic fluorescent surfactant, the 5-FU derivative and 11-bromoundecaonic acid at 5/1/1/3 molar ratio. Langmuir compression isotherms allowed clarifying the influence of lipid organization on the response of the sensor.

The plant alkaloid voacamine (VOA) displays many interesting pharmacological activities thus, considering its scarce solubility in water, its encapsulation into liposome formulations for its delivery is an important goal. Different cationic liposome formulations containing a phospholipid, cholesterol and one of two diasteromeric cationic surfactants resulted able to maintain a stable transmembrane difference in ammonium sulfate concentration and/or pH gradient and to accumulate VOA in their internal aqueous bulk. The fluidity of the lipid bilayer affects both the ability to maintain a stable imbalance of protons and/or ammonium ions across the membrane and the entrapment efficiency. It was shown that VOA loaded into liposomes is more efficient than the free alkaloid to revert resistance of osteosarcoma cells resistant to doxorubicin to an extent depending on their composition.

The inclusion of pH-sensitive components in liposome formulations can allow a more controlled and efficient release in response to low pH typical of some pathological tissues and/or subcellular compartments. On the other hand decorating the surface of liposomes with sugar moieties attributes to lipid vesicles specificity toward lectins, sugar-binding proteins overexpressed in many tumor tissues. A novel multifunctional pH-sensitive glucosylated amphiphile was synthesized and characterized as pure aggregate component and in mixtures with a natural phospholipid. The comparison of the properties of the new glucosylated amphiphile with respect to those of a previously described cationic structural analogue demonstrates that the pH-sensitivity can strongly affect drug release, lipid organization, as well as the exposure of the glucose residues on liposome surface and their ability to interact with Concanavalin A, a plant lectin used as model system.

The aggregation properties of a new cationic fluorescent amphiphile tagged on the hydrophobic tail with a pyrene moiety and bearing two hydroxyethyl functionalities on the polar headgroup were investigated by fluorescence experiments as pure components or in mixed liposomes containing an unsaturated phospholipid, 1,2-dioleoyl-sn-glycero-3-phosphocholine, at different molar ratios. The obtained results put in evidence that the conformation and the miscibility of the lipids in the aggregates strongly influence the excimer/monomer ratio. Mixed monolayers at the same composition were investigated by Langmuir compression isotherms to deepen the understanding of lipid organization and miscibility, both in the polar and in the hydrophobic regions. The presence of two hydroxyethyl functionalities on the polar headgroup of the newly synthesized amphiphile exerts a shielding effect of the charge of the amphiphile increasing the compressibility of lipid components in contrast with the disturbing effect of the unsaturated acyl chains of the phospholipid.

Over the past few years, chiral supramolecular assemblies have been successfully used for recognition, sensing and enantioselective transformations. Several approaches are available to control chirality of discrete assemblies (e.g., cages and capsules), but few are efficient in assuring chirality for micellar aggregates. Optically active amino acid-derived surfactants are commonly used to generate chiral spherical micelles. To circumvent this limitation, we benefited from the uniaxial growth of spherical micelles into long cylindrical micelles usually called wormlike or giant micelles, upon the addition of cosolutes. This paper describes the unprecedented formation of chiral giant micelles in aqueous solutions of cetyltrimethylammonium bromide (CTAB) upon increasing addition of enantiopure sodium salt of 1,1?-bi-2-naphthol (Na-binaphtholate) as a cosolute. Depending on the concentrations of CTAB and Na-binaphtholate, chiral gel-like systems are obtained. The transition from spherical to giant micellar structures was probed using rheology, cryo-transmission electron microscopy, polarimetry, and electronic circular dichroism (CD). CD can be effectively used to monitor the incorporation of Na-binaphtholate into the micelle palisade as well as to determine its transition to giant micellar structures. Our approach expands the scope for chirality induction in micellar aggregates bringing the possibility to generate "smart" chiral systems and an alternative asymmetric chiral environment to perform enantioselective transformations.

RATIONALE Sulfur-vulcanized rubber is a three-dimensional polymer network, insoluble in all organic solvents. For this reason, vulcanization products are difficult to study and identify by conventional analytical techniques. To simplify this task, low molecular weight olefins have been used as model compounds (MCs) in place of rubber in vulcanization experiments. METHODS In this work, the vulcanization process was investigated using squalene (SQ) as MC. By-products, intermediates and products were separated by semipreparative reversed-phase liquid chromatography (RPLC) with UV detection. Each fraction was collected, concentrated and characterized by flow injection analysis (FIA) and non-aqueous reversed-phase (NARP) LC coupled to positive atmospheric pressure chemical ionization mass spectrometry (APCI-MS). Under the latter conditions, an Information-Dependent Acquisition (IDA) was performed on a linear ion trap mass spectrometer to obtain structural information. RESULTS Several vulcanized compounds containing up to three SQ molecules, cross-linked with chains involving up to 14 sulfur atoms overall, have been identified along with some of their oxidized products (epoxides and hydroperoxides). The FIA-MS spectra showed peak clusters, each of which included two-three subclusters; the interpretation was complicated by the occurrence of more ion species per product, by the unsaturation grade and by the characteristic isotopic distribution of sulfur. The enhanced product ion scan (EPI) spectra, acquired during the IDA experiments, supported the FIA-MS identification allowing one to count the number of sulfur atoms. CONCLUSIONS The sensitivity of the developed analytical strategy was due to the enrichment factor achieved via semipreparative chromatography and the very good response of the APCI detection. Pattern fragmentation and chromatographic behavior simplified the identification of the cured compounds and their oxidized products, whose occurrence was related to the grade of oxidation of SQ used as reagent. Copyright © 2016 John Wiley & Sons, Ltd.

In a previous investigation, cationic liposomes formulated with new 5-FU derivatives, differing for the length of the polyoxyethylenic spacer that links the N(3) position of 5-FU to an alkyl chain of 12 carbon atoms, showed a higher cytotoxicity compared to free 5-FU, the cytotoxic effect being directly related to the length of the spacer. To better understand the correlation of the spacer length with toxicity, we carried out initial rate studies to determine inhibition, equilibrium and kinetic constants (KI, KM, kcat), and get inside inhibition activity of the 5-FU derivatives and their mechanism of action, a crucial information to design structural variations for improving the anticancer activity. The experimental investigation was supported by docking simulations based on the X-ray structure of thymidine phosphorylase (TP) from Escherichia coli complexed with 3'-azido-2'-fluoro-dideoxyuridin. Theoretical and experimental results showed that all the derivatives exert the same inhibition activity of 5-FU either as monomer and when embedded in lipid bilayer.

Pyrene lipids are useful tools to investigate membrane organization and intracellular lipid trafficking. The molecular interactions controlling the organization of lipid monolayers composed of a cationic amphiphile tagged with a pyrene residue and a saturated or unsaturated phospholipid, namely, 1,2-dimyristoyl-sn-glycero-3-phosphocholine and 1,2-dioleoyl-sn-glycero-3-phosphocholine, were investigated by Langmuir trough isotherms to understand how the molecular structure of the components and their relative amount affect the physicochemical properties of lipid monolayers. The obtained results show that the cationic headgroups and unsaturation of hydrophobic chains strongly affect the organization of the lipid monolayer as a function of the amount of components. On the other hand, the presence of the pyrene moiety does not seem to have a marked influence on the interaction within lipid assembly.

The micellization of chiral enantiopure surfactants, dodecyl- N, N-dimethyl- N-( S)-(1-phenyl)ethylammonium bromide and hexadecyl- N, N-dimethyl- N-( S)-(1-phenyl)ethylammonium bromide, was investigated by circular dichroism spectroscopy and isothermal titration calorimetry. The formation of wormlike micelles (WLMs) upon the addition of sodium salicylate to the aqueous solutions of the surfactant was observed only in the case of hexadecyl- N, N-dimethyl- N-( S)-(1-phenyl)ethylammonium bromide. The presence of WLMs was assessed by cryogenic transmission electron microscopy, rheology, and isothermal titration calorimetry experiments, and their supramolecular chirality was investigated by circular dichroism spectroscopy. Depending on the length of the hydrophobic tail, molecular chirality is transferred into a different chiral supramolecular trait. Our findings demonstrate that hydrophobic interactions by controlling the organization and functions of self-assemblies also control the transcription of the chiral information from molecules to complex supramolecular systems.

Phase properties and lateral distribution of components in lipid membranes are frequently investigated by fluorescence of pyrene-labeled lipids. In particular conditions, at specific component molar fractions, lipid bilayers can present regions organized in regular arrangements, hexagonal lattices, where the acyl chain form regular patterns around the pyrene tagged chain of the labeled component. Liposomes composed of a pyrenyl twin type amphiphile (1) bearing a pyrrolidinium headgroup and either 1,2-dimyristoyl-sn-glycero-phosphocholine or 1,2-dioleoyl-sn-glycero-phosphocholine were investigated by fluorescence spectroscopy and Langmuir compression isotherm techniques in a restricted range of molar fraction, X1, (0.005-0.15) to evaluate the influence of composition, temperature and curvature radius on lipid organization and to assess the eventual organization in super lattice arrangements. Amphiphile 1 presents different characteristics with respect to the Pyr-PC usually used in similar investigations, both in terms of charge and conformational freedom, and its presence has a significant effect on membrane organization. Our results put in evidence that both temperature and the presence of unsaturation strongly influence the presence of hexagonal lattice in lipid bilayers.

An investigation, based on absorption and circular dichroism spectroscopy, was carried out on assemblies formed in water upon the interaction of heteroaggregates, composed of dyes (Congo Red or Evans Blue) and cetyltrimethylammonium bromide (CTAB), with four enantiopure phopshocholines (DMPC, DPPC, DOPC, and POPC) characterized by the same polar head and different hydrophobic tails. The results show that the nature of the lipid as well as the concentration ratios influence sensitively the absorption and chiroptical properties of the supramolecular structure. Intriguingly, the transfer of chirality from the lipid to the assembly may be triggered or not, depending on the nature of the lipid hydrophobic chain. These findings confirm the fundamental role of hydrophobic interactions in the transcription of chirality from molecules to complex architectures.

Cationic liposomes have been intensively studied both in basic and applied research because of their promising potential as non-viral molecular vehicles. This work was aimed to gain more information on the interactions between the plasmamembrane and liposomes formed by a natural phospholipid and a cationic surfactant of the gemini family. The present work was conducted with the synergistic use of diverse experimental approaches: electro-rotation measurements, atomic force microscopy, ?-potential measurements, laser scanning confocal microscopy and biomolecular/cellular techniques. Electro-rotation measurements pointed out that the interaction of cationic liposomes with the cell membrane alters significantly its dielectric and geometric parameters. This alteration, being accompanied by significant changes of the membrane surface roughness as measured by atomic force microscopy, suggests that the interaction with the liposomes causes locally substantial modifications to the structure and morphology of the cell membrane. However, the results of electrophoretic mobility (?-potential) experiments show that upon the interaction the electric charge exposed on the cell surface does not vary significantly, pointing out that the simple adhesion on the cell surface of the cationic liposomes or their fusion with the membrane is to be ruled out. As a matter of fact, confocal microscopy images directly demonstrated the penetration of the liposomes inside the cell and their diffusion within the cytoplasm. Electro-rotation experiments performed in the presence of endocytosis inhibitors suggest that the internalization is mediated by, at least, one specific pathway. Noteworthy, the liposome uptake by the cell does not cause a significant biological damage. © 2014 Elsevier B.V.

In this work a combined theoretical and experimental approach was used to elucidate and describe at the molecular level the basic interactions that drive the transfer of the chiral information from chiral surfactant molecules to dye/surfactant assemblies. It was found that both hydrophobic interactions and relative concentrations strongly influence the chiroptical features of the heteroaggregates. In particular it was observed that, depending on the length of the surfactant hydrophobic chain, the chiral information is transferred to the dye by stabilizing an enantiomer either of a chiral conformer or of a chiral topological arrangement. These findings underline the role of hydrophobic interactions in the transfer of chirality and provide an example of the potential of in silico simulations for providing an accurate description of the process of chirality propagation.

The recognition of the enantiomeric couples of ditryptophan in Langmuir films of N -hexadecanoyl- l -proline was investigated by surface pressure–area ( π – A ) isotherm measurements and Brewster angle microscopy experiments. The π – A isotherms relative to the films including the enantiomeric dipeptides show small differences whereas an evident enantiodiscrimination is observed by Brewster angle microscopy images.

Two new steroidal spiroannulated calix[4]pyrroles 5 and 10, derived from bile acids (lithocholate), were prepared by the acid catalyzed condensation of methyl-3,3-bis(pyrrol-2-yl)-5beta-cholan-24-oate 3 with carbonyl compounds and with 2,2'-propane-2,2-diylbis(1H-pyrrole), respectively. The new compounds were fully characterized by physicochemical methods.

The investigation of chiral recognition in micelles and liposomesused as biomembrane models relies, in principle, on physicochemicaltools, such as circular dichroism, NMR spectroscopy, and theoreticalcalculations. However, the need for proper model aggregates andsuitable markers of chirality has prompted us to face some organicsynthesis exercises with problems that synthetic chemists usuallyfind with much more complex syntheses. Our synthetic efforts werecompensated by the results we got in the successive physicochemicalinvestigations. 1 Introduction 2 The Chirality Markers 3 The Amphiphilic Components and the Models 4 The Tools: Some Brief Remarks 5 After All the Work: The Results 6 Concluding Remarks

Lipid-based drug carriers, such as liposomes or drug/lipid complexes, have been extensively investigated in a large number of therapeutic protocols such as gene therapy, drug delivery, drug targeting and antibacterial treatments, in preclinical and clinical trials. Many formulations composed of natural and/or synthetic amphiphiles have been studied. Many synthetic lipids and surfactants have been designed and tested in order to improve liposomes and lipid complexes performances, such as fusion with cellular membrane, cellular uptake, target selectivity, transfection efficiency, low toxicity. Among these, gemini surfactants have been shown to be highly effective in delivering genetic material to cells, and also have been shown promising as synthetic additives in liposome formulations for drug delivery. The encouraging results obtained in gene therapy have given impulse to chemist creativity: an extensive selection of pH sensitive, sugar-, aminoacid- , and peptide-based gemini surfactants have been developed, many of which have shown good biological features. This review focuses on recent progress in gemini surfactant based formulations and their applications in different therapeutic protocols.

The inclusion of poly(ethylene glycol) monolaurate in liposomes formulated with dimyristoyl-sn-glycero-3-phosphocholine and certain cationic gemini surfactants improves their capability of condensing DNA into a psi phase and transfecting it into cells. Both the condensation, observed by circular dichroism, and the transfection efficiency are strongly effected by the protocol of inclusion of the polymer in the formulations. The highest transfection efficiency is observed in correspondence of the highest extent of DNA condensation.

Antimicrobial photodynamic therapy is emerging as a promising therapeutic modality for bacterial infections. Our studies aim at identifying strategies for optimizing the antibacterial activity of porphyrin-type photosensitisers. The photoinactivation properties of a novel, positively charged meso-substituted porphyrin, namely 5-[4-(1-dodecanoylpyridinium)]-10,15,20-triphenyl-porphyrin were tested against a typically antibiotic-resistant pathogen, such as methicillin-resistant Staphylococcus aureus. This porphyrin is characterized by an unusually large quantum yield (0.95) for the generation of the hyper-reactive oxygen species, singlet oxygen. In spite of this, it exhibits a relatively low photosensitising activity against bacteria when dissolved in a homogeneous aqueous solution or incorporated into neutral lipid vesicles. On the contrary, a dramatic potentiation of the photocydal effect takes place when polycationic agents such as liposomes of N-[1-(2,3-dioleoyloxy)propyl]-N,N,N-trimethylammonium chloride are used as carriers. The cationic carrier primarily acts as a disorganizing agent for the native three-dimensional architecture of the bacterial wall, thereby enhancing its permeability to the photosensitiser. Consequently, the drug can deeply penetrate into the plasma membrane, and rapidly impair selected enzymic activities leading to cell death. Thus, the combination of positively charged drugs and cationic delivery systems appears to represent an innovative modality for achieving an efficient antimicrobial activity and opens new avenues for the development of this phototherapeutic application.

Malignant gliomas represent the most common primary brain tumor: more than 50% of them are glioblastoma multiforme (GBM). Photodynamic therapy may offer a very good chance of targeted destruction of infiltrating GBM cells, thus increasing the survival time and recurrence-free interval of GBM patients. Among photosensitizing agents, meta-tetrahydroxyphenylchlorin (m-THPC) is promising for the treatment of brain tumors. In previous studies, we investigated the transfection activity of dimyristoyl-sn-glycero-phosphatidylcholine (DMPC) liposomes, containing a cationic gemini surfactant, loaded with m-THPC on human colon adenocarcinoma and glioblastoma cell lines. In this paper, the uptake and the intracellular distribution of m-THPC, loaded in several formulations of cationic liposomes, were analyzed, by making a comparison with those obtained using the same chlorin in the pharmaceutical form (Foscan(R)). Moreover, by cloning efficiency assay the potential therapeutic efficiency of chlorin delivered by liposome formulations was compared with that of the pharmaceutical compound, before and after irradiation with laser light at 652 nm. The obtained results indicated that cationic liposomes (i) transferred m-THPC in glioblastoma cells more efficiently than pharmaceutical formulation; (ii) significantly (p < 0.001) increased the m-THPC cytotoxic effect after laser irradiation; (iii) seemed to exert their cytotoxic action in the early phase of interaction with the cells, during adhesion to the plasma membrane.

New types of porphyrin derivatives bearing "C-glycoside" moieties, either in 5,10,15,20- or in 5,15-meso-positions, were prepared and fully characterized. The presence of the glycosidic groups imparts to the title macrocycles, besides an amphiphilic character, a clear tendency to form chiral suprastructures upon solvent-driven self-aggregation in different aqueous-organic solvent mixtures. Supra-assembly phenomena, in terms of the size and morphology of the resulting structures, as well as their kinetics of aggregation, were studied by UV-visible, fluorescence, resonance light scattering (RLS), and CD spectroscopy, indicating that the morphology of the aggregates depends strongly on the structure of the porphyrin rings, and on the bulk conditions of aggregation.

Sulfur-vulcanized rubber is a three-dimensional polymer network, insoluble in all organic solvents. For this reason, vulcanization products are difficult to study and identify by conventional analytical techniques. To simplify this task, low molecular weight olefins have been used as model compounds (MCs) in place of rubber in vulcanization experiments.In this work, the vulcanization process was investigated using squalene (SQ) as MC. By-products, intermediates and products were separated by semipreparative reversed-phase liquid chromatography (RPLC) with UV detection. Each fraction was collected, concentrated and characterized by flow injection analysis (FIA) and non-aqueous reversed-phase (NARP) LC coupled to positive atmospheric pressure chemical ionization mass spectrometry (APCI-MS). Under the latter conditions, an Information-Dependent Acquisition (IDA) was performed on a linear ion trap mass spectrometer to obtain structural information.Several vulcanized compounds containing up to three SQ molecules, cross-linked with chains involving up to 14 sulfur atoms overall, have been identified along with some of their oxidized products (epoxides and hydroperoxides). The FIA-MS spectra showed peak clusters, each of which included two-three subclusters; the interpretation was complicated by the occurrence of more ion species per product, by the unsaturation grade and by the characteristic isotopic distribution of sulfur. The enhanced product ion scan (EPI) spectra, acquired during the IDA experiments, supported the FIA-MS identification allowing one to count the number of sulfur atoms.The sensitivity of the developed analytical strategy was due to the enrichment factor achieved via semipreparative chromatography and the very good response of the APCI detection. Pattern fragmentation and chromatographic behavior simplified the identification of the cured compounds and their oxidized products, whose occurrence was related to the grade of oxidation of SQ used as reagent. Copyright © 2016 John WileySons, Ltd.

Enantiodiscrimination of ditryptophan enantiomers ( l -Trp- l -Trp and d -Trp- d -Trp, l -Trp- d -Trp and d -Trp- l -Trp) was observed in bio-membrane models, such as micellar aggregates of 1,2-diheptanoyl-sn-glycero-3-phospatidylcholine (DHPC) and multilamellar vesicles of either 1-palmitoyl-2-oleoyl-sn-glycero-3-phosphocholine (POPC) or 1,2-dimyristoyl-sn-glycero-3-phospatidylcholine (DMPC) by solution 1H NMR and HR-MAS 1H NMR, respectively. The attainment of resolved signals, allowed the first detection of enantiodiscrimination at a molecular level, and the identification of the site of chiral recognition and of the interactions and conformations of homo- and heterochiral dipeptides in large-sized aggregates formed by a common component of bio-membranes.

One of the most prominent hallmarks of apoptotic cells is the altered characteristics of their plasma membrane, with its blebbing and exposure of the anionic phospholipid, phosphatidylserine (PS), in the outer leaflet of the lipid bilayer. The latter feature provides the basis of distinguishing apoptotic cells from most normal cells due to staining with fluorescently labeled annexin V, binding specifically to PS. In this article, we report on the binding to apoptotic leukemic T cells (Jurkat cell line, treated with different apoptotic inducers) of cationic liposomes (CLs) composed of the cationic gemini surfactant SS-1 ((2S,3S)-2,3-dimethoxy-1,4-bis(N-hexadecyl-N,N-dimethylammonium)butane dibromide), the fluorescent lipid analog DOPRho (1,2-dioleoyl-sn-glycero-3-phosphoethanolamine-N-(lissamine rhodamine B sulfonyl)), and POPC (1-palmitoyl-2-oleoyl-sn-glycero-3-phosphocholine). Control cells showed negligible and irregular binding patterns of CLs, whereas apoptotic cells revealed a strongly augmented staining of their plasma membrane. Morphological observations and comparison with standard procedures for detecting apoptotic cells further demonstrated the binding of CLs to be intense for cells undergoing apoptosis. In addition, some apoptotic cells with higher caspase-3 activity also revealed more pronounced staining by CLs. Our data suggest that the binding of CLs to apoptotic cells is mediated through an electrostatic interaction between the positively charged head group of SS-1 and the translocated anionic phospholipid PS in the plasma membrane. Because the fluorescent lipid tracer can be freely selected, this approach provides convenient and versatile means for the fluorescence detection of apoptotic cells.

The inclusion behaviour of porphyrin derivative manganese [5-(4-(carboxyphenyl-( N - l -proline)))-10-15-20-triphenylporphyrinyl] chloride 1MnCl in micellar aggregates of sodium N -dodecanoyl- l -prolinate L-SDP and of sodium dodecylsulfate SDS has been studied by means of several spectroscopic techniques. The catalytic activity in the epoxidation reaction of some test chiral olefins has been also investigated. Comparison with the case of the related manganese[5-(4-carboxyphenyl)-10-15-20-triphenylporphyrinyl] chloride 2MnCl , gave evidence that suggests the presence of a chiral functionality on the periphery of porphyrin macrocycles affects their aggregation mode within the biomembrane models. This results in the modulation of their stereoselective Cytochrome P450 biomimetic activity.

A CD band in chiral recognition experiments on racemic stereolabile compounds can be ascribed either to deracemization or to a solely induced CD effect. A procedure is presented that allows one to discriminate positively between the two phenomena. The procedure, based on CD spectroscopy, was used in experiments on racemic biphenylic derivatives in aggregates formed by enantiopure surfactants. In addition to demonstrating a deracemization event, the procedure allowed us to measure the enantiomeric excess.

Energy dispersive X-ray diffraction (EDXD) measurements were conducted on fully hydrated samples of the cationic gemini surfactant (2S,3S)-2,3-dimethoxy-1,4-bis(N-hexadecyl-N,N-dimethylammonium)butane dibromide, SS, as a function of temperature. The surfactant molecules self-assemble into multilamellar vesicles with a well-defined d-spacing which decreases as temperature increases. The derived structural parameters, such as bilayer thickness, size of the water region interbilayer, number of water molecules per surfactant molecule reveal reduced bilayer fluctuations, as a function of increasing temperature, consistent with the observed reduction of the water layer.

Differential scanning calorimetry (DSC) revealed the stereochemical structure of the headgroup to be an important determinant for the thermal phase behavior of aqueous dispersions of a cationic gemini surfactant. More specifically, the meso form (2S,3R)-2,3-dimethoxy-1,4-bis(N-hexadecyl-N,N-dimethylammonium)butane dibromide (abbreviated SR-1) exhibited complex pattern of multi-peak endotherms with two more pronounced peaks at approximately 29 °C and 39 °C. Different behaviors were evident for the stereochemically pure enantiomers (2S,3S)-2,3-dimethoxy-1,4-bis(N-hexadecyl-N,N-dimethylammonium)butane dibromide (SS-1) and (2R,3R)-2,3-dimethoxy-1,4-bis(N-hexadecyl-N,N-dimethylammonium)butane dibromide (RR-1), which both had major endotherms at approximately 36 °C and 41 °C. The heating scans recorded for both RR-1 and SS-1 immediately after a heating-cooling cycle were smooth while SR-I demonstrated a simple endotherm at 29 °C. These results suggest that the geometry of the headgroup of the above gemini surfactants is an important determinant for their lateral packing and organization in an aqueous solution reflected as pronounced effects on both thermal phase behavior and relaxation kinetics. In keeping with this interpretation, including either SS-1 or RR-1 at a mole fraction of 0.10 into SR-1 suspensions resulted in lower transition temperatures and enthalpies, thus demonstrating perturbation of the packing of SR-1 by the presence of the stereoisomeric "impurities".

A biomimetic system of cytochrome P450, constituted by [5-(4-(1-methylpyridinium))-10,15,20-triphenylporphyrinato] manganese(III) dichloride (Mn1) included in cetylpyridinium chloride (CPyCl) micellar phase, features good catalytic activity in the NaClO promoted epoxidation of styrene. A closely related system, i.e. [5-(4-(3-trimethylammonium) propyloxyphenyl)-10,15,20-tryphenyl-porphyrinato] manganese(III) dichloride (Mn2) in cetyltrimethylammonium bromide (CTAB), presents a lower reactivity, similar to that achieved in ethanol–water solvent mixture. A crossover experiment, i.e. that carried out with Mn1/CTAB system, shows intermediate degree of conversion. These findings indicate that the catalytic properties of the investigated systems are deeply influenced by the specific non-covalent interactions established among the catalyst, substrate, and surfactant.

The hydration of terminal alkynes and of propargylic alcohols to the corresponding aldehyde derivatives is conveniently carried out at 60°C in an aqueous micellar environment, in the presence of 5 mol% of the indenyl ruthenium(II) complex [Ru(η5-C9H7)Cl(PPh3)2]. Higher yields and improved regioselectivity of aldehyde versus ketone as well as reaction conditions, in particular temperature and catalyst load, are found with respect to a solvent mixture 2-propanol–water, due to the aggregating conditions of the micellar solution. The reactions of the propargylic alcohols indicate the tolerance of the hydroxy functionality by the ruthenium complex.

Monolayers of a cationic gemini surfactant, 2,3-dimethoxy-1,4-bis(N-hexadecyl-N;N-dimethyl-ammonium)butane dibromide (abbreviated as SS-1) and its mixtures with 1-palmitoyl-2-oleoyl-sn-glycero-3-phosphocholine (POPC) were studied using a Langmuir balance. More specifically, we measured the force-area (pi-A) curves and determined the elastic area compressibility modulus (C) as a function of lateral packing pressure and the mole fraction of the cationic lipid (X(SS-1)), with and without DNA in the subphase. Both SS-1 and POPC exhibited smooth compression isotherms, indicating their monolayers to be in the liquid expanded state. Even low contents (X(SS-1) < 0.05) of SS-1 in a POPC monolayer condensed the film dramatically, up to 20% at 30 mN/m. This effect is suggested to reflect reorientation of the P(-)-N(+) dipole of the POPC headgroup. Accordingly, the magnitude of the condensing effect diminishes with X(SS-1) and is not observed for mixed films of dioleoylglycerol and SS-1. Reorientation of the P(-)-N(+) dipole is further supported by the pronounced increase in monolayer dipole potential psi due to SS-1. The presence of DNA in the subphase affected the mixed POPC/SS-1 monolayers differently depending on the constituent lipid stoichiometry as well as on the DNA/SS-1 charge ratio. At a DNA concentration of 0.63 microM (in base pairs) condensation of neat POPC monolayers was evident, and this effect remained up to X(SS-1) < 0.5, corresponding to DNA/SS-1 charge ratio of 1.25. An expansion due to DNA, evident as an increase in DeltaA/molecule, was observed at X(SS-1) > 0.5. At a higher concentration of DNA (1.88 microM base pairs) in the subphase corresponding to DNA/SS-1 charge ratio of 3.75 at X(SS-1) = 0.5, condensation was observed at all values of X(SS-1).

The reversible enantiomerization of axially chiral 2′-dodecyloxy-6-nitrobiphenyl-2-carboxylic acid was studied in the presence of a brush type chiral stationary phase based on O-(tert-butylcarbamoyl) quinine as chiral selector unit by stopped-flow high-performance liquid chromatography (sfHPLC) and capillary electrochromatography (sfCEC). After initial separation of the enantiomers in the first section of the column, the flow was stopped and the resolved species allowed to enantiomerize on-column. From this conversion, which could be determined from the enantiomeric ratios at different enantiomerization times, kinetic rate constants were calculated. By sfHPLC at a constant temperature of 15°C, kinetic rate constants in the presence of the CSP were found to be 4.1 × 10−5 s−1 and 2.2 × 10−5 s−1 for the (−) and (+)-enantiomers, respectively, corresponding to half-lives of 279 and 530 min. Thus, apparent activation energies of enantiomerization were calculated to be 93.0 and 94.6 kJ mol−1 for the (−) and (+)-enantiomers. On the macroscopic level, the apparent difference of rotational energy barriers and kinetic rate constants for both enantiomers is reflected as deracemization. For example, starting from a racemic mixture, an enantiomeric excess (ee) of 14% was seen in the stopped-flow HPLC experiment described after an enantiomerization time of 220 min at 15°C, and a maximal ee of 17% can be approximated after infinite enantiomerization time. There is good agreement between HPLC and CEC results as well as their experimental errors, confirming that the new sfCEC technique may be a valuable and convenient tool to study interconversion processes. Chirality 13:641–647, 2001. © 2001 Wiley-Liss, Inc.

In this paper we report an NMR investigation on the chiral gemini surfactant (2S,3S)-2,3-dimethoxy-1,4-bis(N-hexadecyl-N,N-dimethylammonium)butane dibromide (1), carried out to study the aggregation in various solvents. If the aggregation equilibrium of 1 can be described by the mass action law model, by observing the variation of chemical shift with respect to [1], we can obtain the aggregation number n. In CDCl3 the values are n = 2 and 19 ± 3, at low and high [1], respectively, indicating that 1 is present in dimeric assemblies and as reversed micelles. In CD3OD, despite evidence that 1 is under aggregating conditions, the model does not hold; 1 should form a relatively flexible structure, because in the 13C NMR spectra 1J(13C,14N) coupling is observed (1J = 3.4 Hz). 1 is scarcely soluble in D2O; in the 1H NMR spectrum of 1 × 10-3 M 1, the signals relative to the tails and to one of the NCH3 groups disappear, while the other head group signals are well resolved, indicating the presence of large assembl...

The phase diagram of the system composed of H2O and tributylhexadecylphosphonium bromide (CTBPBr) has been investigated and the phase boundaries determined. CTBPBr solutions undergo critical demixing phenomena and separate into two fluid phases at temperatures close to 30 °C. Added alkali bromides have some effect on the phase boundaries, which are shifted to lower temperatures, in proportion to the amount of added salt. Additional studies were performed on tributylhexadecylphosphonium sulfate ((CTBP)2SO4) and nitrate (CTBPNO3). In agreement with the behavior predicted by the empirical Hofmeister series, the former does not show the occurrence of consolute boundaries but forms a liquid crystalline phase. The latter is nearly insoluble and transforms from a waxy solid in H2O dispersion to a biphasic fluid system, on increasing temperature. To analyze the role of the counterion, we performed a kinetic investigation of the cyclization reaction of 2-(3-bromopropyloxy)phenol (PhBr7) in dilute aqueous solutions...

Chiral discrimination of racemic 2-carboxy-2‘-dodecyloxy-6-nitrobiphenyl by aqueous micelles of sodium N-dodecanoyl-l-prolinate was observed by 1H NMR. 2D ROESY experiments show that the biphenylic system interacts preferentially with one of the two domains respectively formed by the E and Z isomers of sodium N-dodecanoyl-l-prolinate and that the biphenylic solute induces larger and more rigid aggregates. An estimate of the rotational barrier of the biphenylic system both in aggregating and in nonaggregating conditions has been carried out by dynamic NMR, and results are in good agreement with reported data obtained by racemization rates.

In this paper we report the multinuclear NMR investigation of sodium N-dodecanoyl-L-prolina (1), in CD 3 OD and in D 2 O, at various concentrations. Due to the amide bond, this surfactant has two conformational isomers, 1-E and 1-Z, and the ratio [1-E]/[1-Z] in micellized surfactant is different from that in CD 3 OD or in D 2 O at [1] < cmc (ca. 0.5 and 1.5, respectively). Under micellar aggregation conditions, the presence of the two isomers resulted in two signals for most of the nuclei. Because this feature is not observed under nonaggregating conditions, this indicates that the isomers micellize on the basis of different stereochemical code in conformational domains that give two different 1 H and 13 C NMR spectra. 23 Na spin relaxation time shows that the counterion is highly bonded to the aggregate.