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Glucosylated liposomes composed of the natural saturated phospholipid 1,2-dipalmitoyl-sn-glycero-3-phosphocholine (DPPC), cholesterol (Chol) and a cationic amphiphile featuring a glucosyl moiety (GL4), have been developed for delivering the antimicrobial trans-Resveratrol (RSV) to S. epidermidis, characterized by carbohydrate-specific adhesins able to recognize glucose. The cationic derivative of cholesterol, DC-Chol, was also included in liposome formulations, alone or in combination with GL4, in order to explore the role of both cationic charge and sugar moiety in the interaction of liposomes with bacterial cells. RSV was included inside glucosylated cationic liposomes by the thin film method, coupled with either extrusion or sonication; liposome mean diameter, polydispersity index, surface charge, RSV entrapment efficiency and concentration have been measured by DLS, electrophoretic mobility, and HPLC. The antimicrobial activity of RSV-loaded liposomes was evaluated by monitoring the bacterial growth curves of two cell lines of Staphylococcus epidermidis, a slime positive strain (i.e. a strain able to form a biofilm) and a slime negative one. Results point out that, when the glucosylamphiphile GL4 is included in the formulation, only the extrusion protocol allows obtaining monodisperse liposomes with high RSV entrapment efficiency. The mean diameters of empty and resveratrol-loaded liposomes are all around 120-140 nm and size distribution are narrow, except for samples including GL4 at 5 molar percentage. Here the higher polydispersity index may be the indication of the occurrence of a restructuring phenomenon. The microbiological tests put in evidence a different response of the two bacterial cell lines to liposome treatments, in fact, the slime negative bacterial cells, that are not able to produce the extracellular polymeric substances, are more susceptible to the cationic charge of the liposomes and to the detergent effect of GL4. The most interesting results concern DPPC/Chol/GL4 liposomes on the slime positive strain: this formulation, non-toxic in itself, displays an enhanced antibacterial efficacy with respect to free RSV, killing bacteria even at concentration tenfold under the MIC.

The C1858T variant of the protein tyrosine phosphatase N22 (

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.

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.

Three new fluorescent molecular rotors were synthesized with the aim of using them as sensors to dose thymidine phosphorylase, one of the target enzymes of 5-fluorouracil, a potent chemotherapic drug largely used in the treatment of many solid tumors, that acts by hindering the metabolism of pyrimidines. 5-Fluorouracil has a very narrowtherapeutic window, in fact, its optimal dosage is strictly related to the level of its target enzymes that vary significantly among patients, and it would be of the utmost importance to have an easy and fast method to detect and quantify them. The three molecular rotors developed as TP sensors differ in the length of the alkylic spacer joining the ligand unit, a thymine moiety, and the fluorescent molecular rotor, a [4-(1-dimethylamino)phenyl]-pyridinium bromide. Their ability to trigger an optical signal upon the interaction with thymidine phosphorylase was investigated by fluorescent measurements.

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.

Novel cationic glycoliposomes, composed of 1,2-dioleoyl-sn-glycero-3-phosphocholine (DOPC), cholesterol (Chol) and glycoamphiphiles featuring a galactosyl, mannosyl or glucosyl moiety have been investigated for the targeted delivery of trans-resveratrol (RSV), a Quorum Sensing Inhibitor (QSI), to Methicillin Resistant Staphylococcus Aureus (MRSA) biofilms. All the glycosylated formulations show a 10–20 % reduction of their hydrodynamic size and a high positive increase in ζ-potential (20÷27mV), with respect to the almost neutral DOPC/Chol liposomes (-3.7 mV). RSV is entrapped in liposomes with high Entrapment Efficiency (EE%), the formulations containing glycosylated amphiphiles showing higher values of EE% (79–90 %) than those containing DOPC/CHOL (65 %). In all the liposomal formulations, the inclusion of RSV causes a decrease in ζ-potential, which is particularly evident in the negative value of DOPC/Chol liposomes (-14.8 mV). This is probably due to the ionization of a small percentage of RSV molecules that point towards the lipid/water interface, as reported in the literature. Greater antioxidant activity is found when RSV is embedded in glycosylated liposomes, rather than DOPC/CHOL liposomes. This finding suggests a different RSV distribution in the lipid membrane enclosing the glycosylated amphiphiles, which favor an external exposure of RSV. Biological assays carried out to monitor the demolition effect of RSV-loaded liposomes on mature biofilm of MRSA show that the presence of cationic glycoamphiphiles is essential for a demolition effect to take place on the biofilm matrix. In particular, RSV-galactosylated liposomes are the most effective in destroying MRSA biofilm even at a RSV concentration (0.019 mM) sixty times lower than the MIC (1.2 mM). This work demonstrates, for the first time, how the functionalization of liposomes with cationic glycosydic residues can enhance liposome performances as QSI nanocarriers for the treatment of biofilm associated infections.

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.

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.

(+)-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.

In the wide panorama of diacetylenic lipids, the photoresponsive conjugated 1,3-diyne function is usually encased into the hydrocarbon chain of the amphiphile at a variable distance from the headgroup. Therefore, the polydiacetylene network obtained by polymerization upon UV irradiation of the corresponding liposomes, exploited as sensing function, is embedded in the hydrophobic region of liposomes. Structurally related cationic diacetylenic amphiphiles featuring the conjugated triple bonds proximate to charged nitrogen were synthesized and evaluated in their ability to polymerize under aggregative conditions. The occurrence of polymerization only in certain aggregating conditions was rationalized by nuclear magnetic resonance (NMR) and Langmuir trough experiments.

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.

In autoimmune diseases as Type 1 diabetes, the actual treatment that provides the missing hormones is not able, however, to interrupt the underlining immunological mechanism. Importantly, novel immunotherapies are exploited to protect and rescue the remaining hormone producing cells. Among probable targets of immunotherapy, the C1858T mutation in the PTPN22 gene, which encodes for the lymphoid tyrosine phosphatase (Lyp) variant R620W, reveals an autoimmunity related pathophysiological role. Our scope was to establish new C1858T PTPN22 siRNA duplexes delivered by liposomal carriers (lipoplexes) to patients' PBMC. Following lipoplexes treatment, CD3+ and CD3- immunotypes were efficiently transfected; cell integrity and viability were preserved. Specific target mRNA down-modulation was observed. After T cell receptor stimulation, in lipoplexes-treated PBMC Lyp function was restored by increased release of IL-2 in cultures. Results set-up the stage for ultimate trials in the treatment of autoimmunity based on the specific inhibitory targeting of C1858T PTPN22 by lipoplexes.

Because of the increased incidence of infections caused by resistant pathogens, due to the intensive use of antibiotics, there is an urgent need to develop new therapeutic strategies against bacteria, possibly based on non conventional drugs. (+)-Usnic acid is a natural compound that exerts a potent antibacterial activity, however its clinical application is hampered by its scarce solubility in water. Usnic acid was included, by both passive and active loading techniques, in liposomes containing structurally related glucosylated amphiphiles. Liposome formulations were characterized from the physicochemical point of view and their activity against biofilm associated Staphylococcus epidermidis was also evaluated. The inclusion of usnic acid in glucosylated cationic liposomes promotes its penetration in biofilm matrix with a consequent increase of its antimicrobial activity. The effect of both cationic charge and sugar residue seems to be synergistic.

Liposomes functionalized on their surface with carbohydrates (glycoliposomes) represent an optimal approach for targeting of drugs to diseased tissues in vivo, thanks to biocompatibility, low toxicity and easy manufacturing of these lipid nanoparticles. Here we report on the study of liposomes including a novel glycosylated amphiphile and on the comparison of their features with those of glycosylated analogues described previously. Further, the capability of the different glucosylated formulations to interact with three breast cancer cell lines was investigated. Our results show that the hydrophobic portion of the lipid bilayer strongly influences both the properties and the internalization of glycosylated liposomes.

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.

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.

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.

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.

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.

The presence of carbohydrate-binding proteins (i.e. lectins) on the surface of various bacterial strains and their overexpression in some tumor tissues makes the use of glycosylated liposomes a promising approach for the specific drug delivery in antibacterial and anti-cancer therapies. However, the functionalization of liposome surface with sugar moieties by glycosylated amphiphiles does not ensure the binding of sugar-coated vesicles with lectins. In fact, the composition and properties of lipid bilayer play a pivotal role in the exposure of sugar residues and in the interaction with lectins. The influence of the length of the hydrophilic spacer that links the sugar to liposome surface and of the presence of saturated or unsaturated phospholipids in the lipid bilayer on the ability of glucosylated liposomes to interact with a model lectin, Concanavalin A, was investigated. Our results demonstrate that both the chain length and the prensece of unsaturation, parameters that strongly affect the fluidity of the lipid bilayer, affect agglutination. In particular, agglutination is favored when liposomes are in the gel phase within a defined range of temperature. Moreover, the obtained results confirm that the length of the PEG spacer, that influences both lipid organization and the exposure of sugar moieties to the bulk, plays a crucial role in liposome/lectin interaction

Poly(ethylene glycol) (PEG) stabilized liposomes are widely used in drug delivery research because these surface grafted polymers stabilize liposomes in blood stream. However, hydrophilic polymers also affect lipid membrane organization and it is fundamental to investigate their effect on the physicochemical properties of lipid bilayers as well as on their interaction with biological membrane. PEG monolaurate was included in liposomes formulated with dimyristoyl-sn-glycero-3-phosphocholine and one of two cationic gemini surfactants that differ each other for the configuration of a stereogenic center on the polar headgroup. These formulations previously showed good efficiency as drug and DNA delivery systems. The effect of the presence of different amounts of a PEG-lipid and of the liposome preparation protocol was investigated by turbidimetry, dynamic laser light scattering, differential scanning calorimetry and electrophoretic mobility. Flow cytometry and laser scanning confocal microscopy on murine (C6) and on human glioblastoma (LN229) cell lines were also carried out to evaluate the influence of pegylation and of the protocol of preparation on the interaction of liposomes with the biological milieu.

The use of chiral surfactants results in a powerful tool to form chiral assemblies of (L)proline-functionalized porphyrin derivatives in EtOH/H[Formula: see text]O exploiting hydrophobic effect. The formation of chiral heteroaggregated species strictly depends both on the configuration of the chiral center of the surfactant and on its concentration, opening the possibility to tune the supramolecular asymmetry of the final structures.

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