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Peripherally inserted central venous catheters (PICC) have been proposed as an alternative to central venous catheters (CVC). The aim of this study was to determine the thrombosis rate in relation to PICC placement in patients discharged from the intensive care unit (ICU).Data of patients admitted to the ICU (Careggi Teaching Hospital, Florence, Italy; January-August 2008) and discharged with a central venous device were sequentially studied. During the first 4 months, CVCs were used (CVC group), whereas during the last 4 months, PICCs were used (PICC group). Demographic/clinical and catheter-related data were collected. Intensivists performed Doppler examination at ICU discharge and 7, 15, and 30 days after placement.Data of 239 patients were analyzed (125 of CVC group, 114 of PICC group). A total of 2,747 CVC-days and 4,024 PICC-days of observation were included. Patient characteristics were comparable between groups. Patients with PICC had a significantly higher incidence rate of deep venous thrombosis (DVT) than patients with CVC (27.2 vs. 9.6%, P = 0.0012). The rate of DVT/1,000 catheter days was 4.4 for CVCs and 7.7 for PICCs. Eighty percent of DVTs occurred within 2 weeks after insertion. Binary logistic analysis showed a two-fold increased risk for women and a three-fold increased risk when using the left basilic vein in the PICC group.In our post-critically ill population, PICCs were associated with a higher rate of DVT complications than CVCs. Routine ultrasound surveillance for the first 2 weeks after patient discharge from the ICU with a PICC and preferential use of CVC for these patients may be warranted.

Lipoplexes with different surface charge were prepared from a short oligonucleotide (20 mer, dsAT) inserted into liposomes of 1,2-dioleoyl-3-trimethylammonium-propane (DOTAP) and 1,2-dioleoyl-sn-glycero-3-phospho-ethanolamine (DOPE). The starting liposomes were prepared by two different procedures, i.e. progressive dsAT addition starting from plain liposomes (titration) and direct mixing of dsAT with pure liposomes (point to point preparation). Lipoplexes were characterized from a molecular point of view by Electron Spin Resonance (ESR) of a cationic spin probe and by Nuclear Magnetic Resonance. Structural and surface features were analysed by Zeta potential (zeta) measurements and Cryo-TEM micrographs. The complete set of results allowed to demonstrate that: i) the interactions between dsAT and cationic lipids were strong and occurred at the liposome surface; ii) the overall shape and physicochemical properties of liposomes did not change when short nucleic acid fragments were added before surface charge neutralization; iii) the bilayer structure of the lipids in lipoplexes was substantially preserved at all charge ratios; iv) the physical status of lipoplexes with electrical charge far from neutrality did not depend on the preparation method.

The physico-chemical properties of beta-lactosyl-closo-orthocarborane in water solution were investigated by multinuclear NMR, (13)C NMR relaxation, and ab-initio calculations. This molecule represents a potentially selective boron carrier in Boron Neutron Cancer Therapy (BNCT) and exhibits amphiphilic characteristics. Its structural and dynamic features were studied comparing NMR data acquired in both aggregating and non-aggregating conditions. Aggregates are characterized by rapid exchange with the bulk and by high sensitivity to temperature conditions. An unusually stable intra-molecular CH...O hydrogen bond was found to persist in water solution both for the free molecules and after aggregate formation. At the same time, inter-molecular specific CH()O interactions do not seem effective in the aggregate formation process, which appears to take place only on non-specific hydrophobic basis.

Cationic liposomes are widely used as carriers of biomolecules specifically targeted to the cell nucleus. p -Boronphenylalanine (BPA) is a powerful anti-tumor agent for Boron Neutron Capture Therapy (BNCT). In this paper, 1 H and 13 C NMR was used to study the insertion of BPA in mixed liposomes, made up by the positively charged 1,2-dioleoyl-3-trimethylammonium-propane (DOTAP) and the zwitterionic 1,2-dioleoyl- sn -glycero-3-phosphoethanolamine (DOPE). The boronated drug was distributed between the water phase and the liposomes. The location site of BPA into the lipid bilayer was investigated and the boron-substituted aromatic ring was found inserted in the hydrophobic region, whereas the amino acidic group was oriented towards the aqueous environment. Further information was given by proton spin-lattice relaxation rates.

The possibility of cationic (di-oleoyltrimethylammonium propane, DOTAP)/(L-a-dioleoylphosphatidyl-ethanolamine, DOPE) liposomes to act as carriers of boronated compounds such as 1,2-dicarba-closo-dodecaboran(12)-1-ylmethyl](h-D-galactopyranosyl)-(1 !4)-h-Dglucopyranoside and 1,2-di-(h-D-gluco-pyranosyl-ox)methyl-1,2-dicarba-closo-dodeca-borane(12) has been investigated by Electron Spin Resonance (ESR) of n-doxyl stearic acids (n-DSA) and Quasi-Elastic Light Scattering (QELS). Both these carboranes have potential use in Boron Neutron Capture Therapy (BNCT), which is a targeted therapy for the treatment of radiation resistant tumors. They were shown to give aggregation both in plain water and in saline solution. Carborane aggregates were, however, disrupted when DOTAP/DOPE liposome solutions were used as dispersing agents. The computer analysis of the ESR spectra from carborane-loaded liposomes allowed to establish an increase of the order degree in the liposome bilayer with increasing carborane concentration, together with a decreased mobility. The same discontinuities of both correlation time and order parameter with respect to temperature variations were observed in carborane-containing and carborane-free liposomes. This suggested that a homogeneous dispersion of nitroxides and carboranes occurred in the liposome bilayer. The ESR line shape analysis proved that no dramatic changes were induced in the liposome environment by carborane insertion. QELS data showed that the overall liposome structure was preserved, with a slight decrease in the mean hydrodynamic radius and increase in polydispersity caused by the guest molecules. D 2004 Elsevier B.V. All rights reserved.

Non-viral vectors represent an important alternative in gene delivery. Among these vectors, cationic liposomes are widely studied, because of their ability to form stable complexes with DNA fragments (lipoplexes). In the present work, we report on the characterization by electron spin resonance (ESR) spectroscopy and zeta potential measurements of cationic liposomes and of their complexes with oligonucleotides. Liposomes were made with a zwitterionic lipid, DOPE, and a cationic lipid, either DOTAP or DC-Chol. Oligonucleotides were the 20-base single strand polyA, the 20-base single strand polyT, and the corresponding double strand dsAT. The zeta potential as a function of the oligonucleotide/lipid+ ratio gave an S-shaped titration curve. Well-defined surface potential changes took place upon charge compensation between the cationic lipid heads and the phosphate groups on the oligonucleotides. The inversion point depended on the specific system under study. The bilayer properties and the changes that occurred with the incorporation of DNA fragments were also monitored by ESR spectroscopy of appropriately tailored spin probes. For all the systems investigated, the ESR spectra showed that no major alteration took place after lipoplex formation and molecular packing remained substantially unchanged. Both zeta potential and ESR measurements were in favor of an external mode of packing of the lipoplexes.

The carrier properties of mixed unilamellar vesicles of fluorocarbon–hydrocarbon surfactants built up with the ammonium salt of a perfluoropolyether and n -dodecylbetaine were investigated by electron spin resonance spectroscopy (ESR). The ESR-active lipophilic nitroxide 5-doxylstearic acid (5-DSA) was used as a model of a lipophilic drug to be carried and delivered into cell membranes. Healthy and malignant colorectal tissues were used as the target cells. Cell suspensions of living tissues were studied in physiological conditions. For the maintenance of the surgically removed tissues, McCoy’s 5A culture medium was used. 5-DSA probe was rapidly delivered from perfluoropolyether (PFPE)/betaine mixed vesicles to the membranes of both healthy and malignant colorectal cells. The analysis of the computed 5-DSA ESR line shapes ensured that no spectral differences occurred when 5-DSA was either introduced directly into the cells or through the intervention of vesicles. This well agreed for an unmodified physical status of the membranes where the probe was mainly localized.

The lactosyl carborane [1,2-dicarba-closo-dodecarboran(12)-1-ylmethyl](β-d-galactopyranosyl)-(1→4)-β-gluco-pyranoside (LCOB) is an amphipilic boron-containing compound intended for boron neutron capture therapy. In this study cryogenic transmission electron microscopy was used to investigate the effects of LCOB on the structure and properties of extruded egg phosphatidylcholine liposomes. The results showed that LCOB concentrations up to at least xLCOB = 0.25 could be included in the preparations without any noticeable effects on the liposomal size or structure. Inclusion of LCOB concentrations corresponding to xLCOB = 0.44 or more gave, however, rise to significant changes in the liposome size distribution and the overall sample structure. In fresh samples no signs of phospholipid solubilization were detected until the molar fraction of LCOB reached 0.82. At this concentration the boronated compound induced, however, formation of open liposomes and threadlike micelles and, furthermore, with time the samp...

In order to study the effects of large-surface-area solids on the formation of biomacromolecules, copper(II)-nucleosides complexes were studied in water at high pH and after contact with the cavity walls of 13X-zeolite. The results were mainly collected by electron spin resonance in continuous (cw-ESR) and pulsed (ESE) wave. Particular attention was dedicated to adenosine as a nucleoside model for the formation of compounds which were fully characterized in alkaline water solution and after adsorption on commercial 13X-zeolite. In aqueous solution, adenosine was coordinated to copper(II) through deprotonated hydroxyl groups in the 2′ and 3′ positions of the ribose unit, with the formation of [Cu(adenosine)2(H2O)2]2−. When adsorbed on zeolite, both cw-ESR and ESE showed that a fraction of the adsorbed complexes did not change their structure and showed high mobility in the zeolite faujasite cavity. The remaining fraction directly interacted with27Al nuclei of the zeolite framework. Other copper(II)-nucleosides behaved in the same manner. Surprisingly enough, alkaline solutions of nucleosides were able to remove copper (II) from zeolite in the form of [Cu(adenosine)2(H2O)2]2− which freely moved in the supernatant aqueous liquid.

Macroscopic and molecular techniques such as differential scanning calorimetry (DSC) and electron spin resonance (ESR), respectively, were used to characterize both structure and dynamics of liposomes built up with dioleoyltrimethylammonium propane (DOTAP) and dioleoylphosphatidylethanolamine (DOPE) lipids. These liposomes are good candidates to act as molecular carriers in cancer therapy, such as, for instance, boron neutron capture therapy (BNCT). DSC revealed that neither Tm nor ΔHm of the gel-liquid crystal phase transition depended on the presence of relatively concentrated exogenous molecules as they are the n-DSA and n-DPC spin probes used in this work. The results suggested that the structure and the internal dynamics of the liposomes did no change after small loading of the paramagnetic probes. This was proved at a molecular level by the computer analysis of the ESR spectra of the above probes, which revealed discontinuities of the motional parameters (correlation times, τ⊥ and τ∥, and order para...

The structural features of vesicles, micelles, and other aggregates spontaneously formed from a fluorinated surfactant (the ammonium salt of perfluoropolyether, PFPE) and a hydrogenated surfactant (n-dodecylbetaine) in dilute water solution were characterized by means of cryo-transmission electron microscopy (cryo-TEM) at different betaine mole fractions. The size distribution of the aggregates was found to depend critically on surfactant composition. In a narrow range of betaine molar fractions (xbet = 0.76−0.79), two different populations of unilamellar and spheroidal vesicles with mean radii of 70−120 and 20−30 nm, respectively, coexisted with globular and, in some cases, threadlike micelles. In the same region, vesicles with openings in the bilayer and disk-shape fragments began to appear. Further increase in betaine molar fraction resulted in an increase of the number of globular micelles and discoid aggregates and, finally, to the complete PFPE solubilization into mixed micelles. The large vesicles ...

A procedure is presented that is based on the detection of Cu(II)–asparagine complexes by quantitative ESR, and allows in a very simple and rapid manner to evaluate the changes of asparagine concentration during the entire time range of the growth of Bacillus subtilis in a typical growth medium. The analysis is carried out in terms of the decrease of the intensity of the ESR-active mono- and di-asparagine–copper(II) complexes. It is resulted that at the end of the exponential growth the asparagine concentration was reduced to values as low as 2% of the initial value. The procedure here reported may be the basis of similar methods to be used for other amino acids and prokaryote systems.

In this study we report a spectroscopic investigation on the structure and stability of Cu(II)-complexes that are formed in a minimum growth medium (MM), normally used for Bacillus subtilis cultures. As other transition metals, Cu(II) compounds are toxic to this bacterium and the toxicity depends on the Cu(II) concentration. MM contained NH 4 + ions and asparagine (asn) as the source of inorganic and organic nitrogen. Both ESR and electronic spectra demonstrated the very important role played by the amino acid asparagine in the coordinative behaviour of Cu(II). In particular, three different complexes were evidenced: Cu(H 2 O) 6 2+ ; Cu(asn) + and Cu(asn) 2 . The relative amount of these three species strongly depended on pH, on Cu:asn ratio and on the presence of the phosphate ions. They were identified and evaluated quantitatively by extensive simulation of the electron spin resonance (ESR) spectra recorded in different experimental conditions. The bis-complex was found to be more stable in MM than in an asparagine-containing water solution with the same Cu:asn ratio. A comparison of the spectroscopic results with microbiological investigations is also made.

The 800-MHz 1H NMR spectra of oxidized plastocyanin from spinach are here reported. All hyperfine-shifted signals have been assigned through saturation transfer with the reduced diamagnetic species. To detect the copper(II)-bound cysteine β-CH2 signals, a technique has been applied which is based on irradiation of regions where such signals are expected but not detected, and the corresponding saturation transfer on the reduced species is observed. At the end, a full spectrum is reconstructed which permits, for the first time, the complete 1H NMR signal assignment of an oxidized blue copper protein. These data are discussed in terms of the factors affecting the line width as related to the electronic and geometric structure of the metal center. A Karplus-type relationship is proposed between the contact shift of the Cys-84 β-CH2 protons and the Cu−S−C−Hβ dihedral angle.

Spontaneously formed mixed vesicles were prepared with n-dodecylbetaine and the ammonium salt of perfluoropolyether carboxylate, and they were loaded with the water-soluble beef heart cytochrome c. The resulting dispersions were characterized with light and neutron scattering patterns, UV -vis spectra, and magnetic resonances (NMR and ESR). Proteins-containing vesicles showed scattering patterns that were interpreted in terms of a decrease of the membrane curvature with a resultant increase of the vesicle size that ranged from 83 to 113 nm, depending on the cytochrome c concentration in the dispersion. The interactions between surfaces of protein and of vesicle membrane, which could be responsible for the decreased curvature, did not alter either the optical properties of the heme unit of the protein (from UV -vis) or the dynamics of the vesicle membrane (from 1 H NMR of betaine and ESR of membrane-soluble doxylstearic acids). Cytochrome c was therefore suggested to be surrounded by a shell of water according to the so-called watershell model. A comparison was made with the behavior of hydrophobic porphyrins introduced in the same vesicle system, as previously reported from the authors.

Direct (dynamic and static light scattering, LS, and nuclear magnetic resonance, NMR) and indirect (electron spin resonance, ESR) techniques allowed us to obtain details on the dynamics and on the structure of betaine micelles and on mixed betaine−perfluoropolyether (PFPE) vesicles. The mixed vesicles formed in a very restricted range of total surfactant concentration and of betaine mole fraction. The occurrence of unilamellar, monodisperse vesicles has been previously shown by LS measurements (Ristori, S.; Appell, J.; Porte, G. Langmuir 1996, 12, 686). ESR from hydrogenated probes (n-doxylstearic acids, n-DXSA) suggested that separate domains existed in the vesicles, and these radicals localized in the betaine-rich domain. A perfluorinated nitroxide radical was synthesized to study the PFPE domain. From the ESR line shapes the dynamic features of the supramolecular assemblies were obtained. Static LS and QELS (quasi-elastic light scattering) ruled out that the addition of nitroxides in the systems under ...

This review analyses the results obtained through the Electron Spin Resonance (ESR) spectroscopy on multilayer Langmuir-Blodgett films fabricated with metal derivatives (mainly Cu 2+ , VO 2+ and low-spin CO 2+ ) of polyazamacrocycles (porphyrins, tetraazaannulenes, phthalocyanines). These metal ions are particularly suitable for an ESR analysis because of their relatively long electron spin relaxation times that render possible their observation even at room temperature and in all co-ordination symmetry. This allows us to obtain valuable data on both mobility and orientation of the metal-macrocycle systems adsorbed onto a solid support. The preliminary characterisation of the spreading monolayer obtained from the systems considered, as it is typically done by surface pressure/area isotherms, optical (UV-Vis) and ESR spectroscopies, is also reviewed.

In this review we describe the use of transition metal ions (Cu2+, Ti3+, VO2+, Mn2+) and stable nitroxide radicals with different shape, size and charge as paramagnetic probes for the study of perfluorinated compounds in the presence of solvents by electron spin resonance (ESR, ESE, ENDOR) spectroscopy. The physical state of the swelling solvents in perfluorinated ionomers (Nafion and perfluoropolyethers) is deduced by the analysis of the ESR spectral parameters and linewidths as a function of the operating frequency and temperature. The formation of metal aggregates in aqueous and nonaqueous solvents is discussed. The spectral characteristics and relaxation behavior of nitroxides is particularly informative when aggregates such as micelles, lamellar phases and other ordered systems, are formed in solution.

The spreading monolayers at the air-water surface of the mesogenic, discotic copper(II) derivatives of 2,3,7,8,12,13,17,18-octakis(alkylthio)porphyrin (CuTAP) have been characterized with the aim of finding the best experimental conditions for fabricating Langmuir-Blodgett (LB) films with columnar aggregates having significant mono- and/or bidimensional properties. The spreading isotherms of pure metal compounds were interpreted in terms of inhomogeneous, rigid surface films, not suitable for LB film deposition. A better transfer was reached with mixtures (e.g. 1 20 molar ratio) of Cu-TAP with the film forming stearic acid, thus obtaining stable and reproducible LB films with more than 300 layers. The film maintained a disordered state of columnar aggregates as proved by electron spin resonance and UV-visible spectroscopy.

The properties of monolayers and multilayers of nickel(II) compounds with the dinaphtho derivative of the macrocycle ligand dinaphtho{ b,i }5,7,12,14-tetramethyltetraaza[14]annulene with one and two hexadecanoyl chains on the water surface and onto a solid support have been studied from a thermodynamic and spectroscopic point of view and the results were compared with those from the dibenzo analogues. The molecular plane showed a tilted edge-on orientation at the air-water interface. The spreading monolayers were stable with time and their stability was almost independent of the compound used. The presence of hysteresis in the compression-expansion-compression cycles indicated an incomplete reversibility. Films prepared with the monohexadecanoyl macrocycle metal derivatives were regular and homogeneous whereas the occurrence of two alkyl chains on the ring resulted in a monolayer too viscous to be transferred. The effect of the film iodination was investigated through UV-visible and electron spin resonance spectroscopies.

Perfluorinated surfactants, likewise their perhydrogenated analogs, give rise in water to micellar and liquid crystal phases, whose structures depend on the surfactant nature, on the temperature and on the composition. Microemulsions can also be formed in ternary systems containing an appropriate oil. Here we report on the characterization by Electron Spin Resonance and by X-ray and neutron scattering (SAXS and SANS, respectively) of ordered and disordered aqueous systems containing either a straight chain perfluorinated surfactant (ammonium perfluorooctanoate, NH4PFO) or more complex perfluoropolyethers (ammonium perfluoropolyether, NH4PFPE, and/or the corresponding oil). Small and large charged and neutral nitroxides have been used as paramagnetic probes inserted into binary and ternary systems. The possibility of perturbing the system by adding an hexogenous compounds is discussed, particularly for more diluted micellar solutions. The analysis of the ESR line shape of long chain spin probes inserted in micellar and lamellar phases and in the microemulsions allowed us to compare the behavior of the differently aggregated phases. These phases were also further proved by SAXS and SANS.

The two-phase and three-pulse electron spin echo techniques were applied to investigate the behavior of doxyl stearic acid spin probes in micellar aqueous solutions of ammonium perfluorooctanoate. Three doxyl stearic acids with the nitroxide group in different positions on the alkyl chain were used as spin probes, and deuteriated water was used to study the deuterium modulation of the echo signals. The experimental patterns were interpreted by best-fit spectra calculated by taking into account both the echo decay and the nuclear modulation. The analysis determines the number of deuterium nuclei in the surroundings of the NO groups and the time constant for the electron spin reorientation causing spectral diffusion and echo decay. From these data we conclude that water molecules belonging to the NO solvation sphere were maintained in the micelles and that the long-chain nitroxide probes were tilted in the micelle core in order to occupy regions with relatively easy water accessibility which was slightly higher for 12-DXSA than for 5- and 16-DXSA. The modulation of the hyperfine couplings of the methyl protons due to their rotational motion was the main mechanism contributing to the echo decay. 44 refs., 4 figs., 2 tabs.

The aggregation properties of ammonium perfluorooctanoate (NH4-PFO) in concentrated aqueous phases have been investigated by magnetic resonance techniques and have been compared with the aggregation properties in dilute solutions. Magnetic resonance methods indicated that NH4-PFO—water systems with surfactant concentrations below 45% (w/w) behaved as isotropic purely micellar solutions in the temperature range 285–340 K. For higher concentrations the system exhibited a rather complex structure, having both isotropic and anisotropic components. The nematic nature of the anisotropic fraction was demonstrated by 19F NMR studies. The 19F NMR and EPR of nitroxides (TempTMA+, 5- and 16-DXSA) inserted as paramagnetic probes into the concentrated NH4-PFO—water systems allowed us to establish that the lamellar phase could be mechanically oriented between quartz slides. The EPR investigation also gave details concerning the dynamics of both the oriented and non-oriented structures.

We report on the use of a copper compound of 2,3,7,8,12,13,17,18-octakis (octylthio)-5,10,15,20-tetraazaporphyrin for the fabrication of a spreading monolayer and Langmuir-Blodgett Films. This compound, as a free ligand or metal substituted, gives mesogenic material with a discotic, columnar structure. Its structural and magnetic properties have been characterized by optical and ESR spectroscopies. The spreading monolayer was not homogeneous and use of a typical film-forming amphiphile, such as stearic acid, was necessary for obtaining stable, reproducible surface films, which were easily transferred onto quartz plates treated with dimethyldichlorosilane. The properties of the film were also analyzed with both UV-vis and ESR spectroscopies

The Langmuir—Blodgett technique has been used for the preparation of magnetic multilayer films of manganese arachidate either as a pure component or in mixture with the diamagnetic methyl arachidate. The mutual surface miscibility of both compounds was verified from the spreading isotherms of their mixtures. The spreading isotherms allowed us to find the optimum conditions for the transfer of monolayers onto silanized quartz plates and to prepare LB films with more than 100 layers. Electron paramagnetic resonance spectroscopy has been used to characterize the magnetic properties of the films. The typical shape anisotropy of quasi-two-dimensional magnets was observed from the orientation dependence in the magnetic field of the linewidth and from the changes of both linewidth and resonance position with temperature at T 5 the usual isotropic properties were observed.

The interactions between monolayers of behenic acid or dihexadecylphosphoric acid (DHP) with mono- and multivalent metal ions in the aqueous subphase were studied tp find the best conditions for the layer transferance on solid supports as LB films. The thermodynamic parameters, the ellipsometric and spectroscopic data allowed us to assess that condensed phases of the monolayer and appreciable surface association between metal ions and ionized amphiphilic were the main requirements to be fulfilled.

An investigation is reported on mono- and multilayers of metal behenates to show the importance of a detailed characterization of the spreading monolayers to find the best conditions for transfer and deposition under the form of Langmuir-Blodgett films. A comparison was made between the properties of copper and manganese behenates as Langmuir-Blodgett forming materials.

Crosslinked perfluoro polyethers are studied in the form of their spin-labeled adducts and after swelling with water solutions containing small nitroxide radicals. The analysis of the SER line shapes revealed a relatively high flexibility of the perfluoro ether backbone. Formation of water pools in the polymer network was suggested on the basis of the ESR results, and the rheological properties of the swelling water were similar to those of water adsorbed in other perfluorinated ionomers

The finding of non-viral carriers for the delivery and release of pharmaceutical and biological compounds to ill organs and tissues is one of the most widely investigated topic in medicinal and biological chemistry in the last decades. Prior to being used as drug vehicles in the living organisms, all of the new carriers are required to be fully characterized from a physico-chemical point of view, with respect to stability, charge, size, mobility, etc. To this aim, several molecular and bulky techniques have been employed for characterization. This review considers the results obtained with a molecularly oriented spectroscopic method, i.e. electron spin resonance (ESR). The application of this technique in its various forms derived from continuous-wave (cw-ESR) and pulsed-wave (pw-ESR) modes are reviewed. In particular, carriers such as liposomes (intended for gene therapy, boron neutron capture therapy, oxymetry, and others), micelles, hydrogels, nanoparticles, dendrimers, cyclodextrins and cucurbit[n]urils are considered.

The conformation of bradykinin (BK), Arg1-Pro2-Pro3-Gly4-Phe5-Ser6-Pro7-Phe8-Arg9, was investigated by Nuclear Magnetic Resonance (NMR) spectroscopy and Monte Carlo simulation in two different media, i.e. in pure aqueous solution and in the presence of phospholipid vesicles. Monolamellar liposomes are a good model for biological membranes and mimic the environment experienced by bradykinin when interacting with G-protein coupled receptors (GPCRs). The NMR spectra showed that lipid bilayers induced a secondary structure in the otherwise inherently flexible peptide. The results of ensemble calculations revealed conformational changes occurring rapidly on the NMR time scale and allowed for the identification of different families of conformations that were averaged to reproduce the NMR observables. These structural results supported the hypothesis of the central role played by the peptide C-terminal domain in biological environments, and provided an explanation for the different biological behaviours observed for bradykinin.

The surface and the aggregation properties of the nickel(II) compounds with the dibenzo- and dinaphtho-tetraazal[14]annulene (TAA) macrocycles have been investigated by their spreading isotherms and electronic spectra. The possibility to form LB films was checked for both compounds. Homogeneous, reproducible LB films were obtained with the dibenzo-TAA derivatives, whereas the high surface viscosity prevented a good multilayer overlapping with the dinaphtho-compound.

Electron spin resonance spectroscopy of doxylstearic acids with the paramagnetic unit inserted in the 5, 6, 7, 9, 12, and 16 carbon position was used to analyze the dynamic and structural features of dioleoylphosphatidylcholine (DOPC) vesicles in the presence and in the absence of ceramide (CER) and as a function of temperature. The sizes and the homogeneity of these lipid aggregates were checked by electron microscopy and turbidimetry

The echo decays of D2O solutions of a positively charged nitroxide radical adsorbed on X- and Y-zeolites are analyzed both for two-pulse and three-pulse sequences. A best-fit simulation procedure is used to obtain data concerning the concentration of adsorbed spins and their reorientational times. The results obtained show noticeable differences depending on the kind of zeolite; limits on the adsorption capacity are also found, that are not linearly dependent on the concentration of the initial solutions. The time-behavior of the spins appears to be determined by the rotation of methyl groups of the radical.

The aggregation of perfluoropolyethers (PFPE) of the general formula CF 3 [OCF 2 CF (CF 3 ) 3-4 OCF 2 COOH in water (in the form of the ammonium salt) has been studied by ESR of a small cationic nitroxide, TempTMA + , which is able to interact electrostatically with the aggregate surface. The ESR lineshapes were computed assuming strongly anisotropic motion, which is typical of partially ordered systems. Lineshapes and hyperfine coupling constants were used to determine the micelle formation and to evaluate approximately the aggregation number.

This review deals with the recent applications of electron spin resonance spectroscopies in surface science. The following topics are considered: (i) adsorbed inorganic radicals; (ii) adsorbed organic radicals; (iii) paramagnetic species on zeolites and on other alumino-silicates; (iv) transition metal ions on catalyst surfaces; (v) micellar and other organized systems; (vi) Langmuir-Blodgett films and other thin films; and (vii) the surface effects on molecular motion of adsorbed species. A table is added to each section with references to the works published in the last few years. Particular attention is given to the combined use of conventional and advanced ESR spectroscopies with other recently developed surface techniques.

The effect of the presence of the sphingolipid ceramide (CER) on the properties of vsicles of dioleoxylphosphatidylcholine (DOPC) has been investigated by electron paramagnetic resonance (EPR) of doxyl stearic acid (DXSA) with the oxazolidinyl ring in different positions on the alkyl chain. CER acted as a condensing agent at temperature near the gel-liquid crystal phase transition temperature (T c ), whereas it acted as a fluidizer at T well above T c . This occurred in the double-layer region from the water-lipid interface down to the double-bond system of the oleoyl residues of DOPC. Spreading isotherms of DOPC and DOPC/CER mixtures at T ∼ T c confirmed the ESR results.

The synthesis, characterization and liposome insertion of a novel magnesium(II) carboranyl-porphyrazine, i.e. [2,3,7,8,12,13,17,18-octakis- (1,2-dicarba-closo-dodecaboranyl)-hexylthio-5,10,15,20- porphyrazine]magnesium(II) complex, MgHECSPz, is described. MgHECSPz was designed to improve the potentiality in multiple approach anticancer therapy. Liposomal formulations with different surface charge were prepared as delivering agents. The obtained loaded vectors were characterized by DLS, SAXS, SANS and \zeta potential measurements in order to define the overall properties and structural details of loaded liposomes.

International audience; In this work the physicochemical characterization of liposomes loaded with a newly synthesised carboranyl porphyrazine (H2HECASPz) is described. This molecule represents a potential drug for different anticancer therapies, such as Boron Neutron Capture Therapy, Photodynamic Therapy and Photothermal Therapy. Different loading methods and different lipid mixtures were tested. The corresponding loaded vectors were studied by Small Angle Scattering (SANS and SAXS), light scattering and zeta potential. The combined analysis of structural data at various length scales and the measurement of the surface charge allowed to obtain a detailed characterization of the investigated systems. The mechanisms underlying the onset of differences in relevant physicochemical parameters (size, polydispersity and charge) were also critically discussed.

Liposome insertion of a newly synthesized octa-carboranylhexylthio-porphyrazine (H2HECASPz) with potentiality in anticancer multiple therapy was described at molecular and supramolecular level. Hos...

Cationic liposomes give rise to stable complexes with DNA molecules (lipoplexes) that are of great interest for gene delivery applications. In particular, liposomes made up by a cationic lipid (DOTAP or DC-Chol) and a zwitterionic lipid (DOPE), produce stable adducts with single and double-stranded DNA oligonucleotides. Formation of these lipoplexes has been further addressed here by circular dichroism spectroscopy (CD) and by other independent biophysical methods. Titration of DNA oligonucleotides with cationic liposomes resulted into significant modifications of their circular dichroic bands. Such spectral modifications were ascribed to progressive DNA condensation and loss of native conformation, as a consequence of the electrostatic interactions taking place between the phosphate groups of DNA and the positively charged head groups of cationic lipids. In all cases, the loss of the CD feature characteristic of the native DNA conformation closely matched the inflection point of Zeta potential profiles. The resulting adducts showed peculiar and non-canonical CD spectra, while exhibiting appreciable stability at physiological pH.

Cationic liposomes-DNA complexes (lipoplexes) are largely used in gene delivery. Deciphering specific chemical and physical properties of lipoplexes is a necessary step to unravel the mechanisms underlying transfection and to improve transfection efficacy in each experimental model. In the present paper we investigated the physico-chemical features of lipoplexes containing a plasmid encoding for the GFP protein, in order to correlate these results with transfection efficacy. Cationic unilamellar vesicles (mean diameter 100 nm) were prepared, from the cationic DC-Chol lipid and the zwitterionic phospholipid DOPE. The two components of the liposome bilayer were used at molar ratio close to unity. ESR spectra were recorded and zeta potential zeta was measured on liposomes complexed with the plasmid. One of the main points of interest in this paper resided in the fact that both kinds of measurements were carried out in the same conditions (i.e. lipid concentration, medium composition, and pH) employed for cell transfection experiments. Transfection was performed on CHO cells; the percentage of fluorescent cells was evaluated and compared with the above physico-chemical features. It emerged that the composition and pH of the medium, the lipoplex/cell ratio, as well as the amount of lipoplex added to the cell culture were critical parameters for transfection efficacy. Finally, lipoplex surface charge played a fundamental role to achieve a high transfection level.

Electron spin resonance (ESR) spectroscopy of nitroxides was used in the study of structural and dynamic features of cationic liposomes built up with 1,2-dioleoyl-3-trimethylammoniumpropane and l-α-dioleoyl-phosphatidylethanolamine surfactants. Particular attention was devoted to the properties of the liposomes after loading with different amounts of boronated compounds such as [1,2-dicarba-closo-dodecarboran(12)-1-ylmethyl](β-d-galactopyranosyl)-(1→4)-β-d-glucopyranoside and 1,2-di-(β-d-glucopyranosyl-ox)methyl-1,2-dicarba-closo-dodecaborane(12), to be used in boron neutron capture therapy (BNCT). The ESR line shapes suggested that the structure and the internal dynamics of the liposomes did not change appreciably after small loading. In contrast, variations in both the mobility and the order degree of the nitroxides inside the bilayer were observed when carborane was loaded in a large amount. ESR spectroscopy was shown therefore to be a valuable tool for the study of liposome properties at a molecular level.

In this communication, the presence of a persistent intramolecular C-H....O bond in solution, has been evidenced by NMR spectroscopy and theoretical calculations. The molecules under study were o-carboranyl beta-glycoside derivatives, in which, the donor group was the activated CH of the carboranyl residue and the acceptor atom was the glycosidic oxygen. The strength of the interaction and the geometry of the atoms involved were determined by ab initio calculations.

Healthy and neoplastic colorectal human tissues of as many as 12 patients have been studied, immediately after surgery, by electron spin resonance (ESR) of stable nitroxides at physiological temperature. Cells were maintained in a living state using the McCoy’s 5A culture medium. The very low concentration changes of hydrophilic and lipophilic nitroxides allowed us to establish that the response to the oxidative stress induced by the occurrence of nitroxides in healthy and tumor cells was very weak, thus suggesting these compounds are good candidates for contrast enhancement agents in magnetic resonance imaging of colorectal tumor. The analysis of the computed ESR line shape of lipophilic nitroxides in both healthy and malignant cells of the same patient agreed for an unmodified physical status of the membranes where they were mainly localized. The results reported here proved that the comparison between ESR results must be made in tissues from the same patient and that the physical status of the membranes depended more on the patient history than on changes in the colorectal cell membrane fluidity induced by the neoplastic process.