Size distribution of dimyristoylphosphatidylcholine liposome suspensions was investigated by dynamic-light scattering (DLS) as a function of the sonication time (t(s)). Cumulant expansion (second- and third-order) and regularized Laplace inversion (CONTIN) of dynamic single-angle laser light-scattering data were performed. With both methods, the intensity-weighted mean hydrodynamic radius r(I) depended on the investigated lengthscale. The number-weighted mean hydrodynamic radius (r(N)), obtained from CONTIN by modeling dimyristoylphosphatidylcholine vesicles as thin-walled hollow spheres, resulted as independent on the lengthscale. However, the r(N) value obtained from cumulant expansions remained lengthscale-dependent. Therefore, the number-weighted radius distribution function is highly asymmetric. The number-weighted mean radius, the standard deviation, and the number-weighted radius at the peak (r(N)(peak)) all decreased to a plateau when increasing sonication time. At t(s) longer than 1 h, the r(N)(peak) compares well with the radius of unilamellar vesicles in equilibrium with monomers predicted on a thermodynamic basis. The reliability of our analysis is proved by the comparison of experimental Rayleigh ratios with simulated ones, using the normalized number-weighted radius distribution function p(N)(r) determined by DLS data. A perfect agreement was obtained at longer sonication times, and the average aggregation number was determined. At lower t(s) values, simulations did not match experimental data, and this discrepancy was ascribed to the presence of large and floppy unilamellar vesicles with ellipsoidal shapes. Our investigation shows that, from single-angle DLS data, the radius distribution function of the vesicles can only be obtained if p(N)(r) is known.

Link to publication in University of Groningen/UMCG research database Citation for published version (APA): Bianconi, A., Congiu Castellano, A., Santis, M. D., Rudolf, P., Lagarde, P., Flank, A. M., & Marcelli, A. (1987). L2,3 XANES of the High Tc Superconductor YBa2Cu3O~7 with Variable Oxygen Content. Solid State Communications, 63(11). https://doi.org/10.1016/0038-1098(87)90650-8 Copyright Other than for strictly personal use, it is not permitted to download or to forward/distribute the text or part of it without the consent of the author(s) and/or copyright holder(s), unless the work is under an open content license (like Creative Commons).Take-down policy If you believe that this document breaches copyright please contact us providing details, and we will remove access to the work immediately and investigate your claim.Downloaded from the University of Groningen/UMCG research database (Pure): http://www.rug.nl/research/portal. For technical reasons the number of authors shown on this cover page is limited to 10 maximum. No evidence of Cu &3d9 final states has been found. This experiment gives direct evidence that additional oxygen x does not give Cu3+ ions with Cu 3d* configuration but gives 3d"L electronic conliguration (I.c. Cu*-Q pairs) and no gap is observed bctwccn the 3d9 (Cu+) and 3d'OL configuration (l.c. C&O-pairs). Thcrcforc in the metallic phase which exhibits superconductivitya continous set of itinerant sta~cs 3d')L and 3ti'"L is obscrvcd. In order to show that the 933 eV peak is quenched with decreasing the oxygen content x we have reduced a sample by heating it in vacuum for 2 h at 400 "C. The 933 eV peak is reduced by the heat treatment as showed in fig. 4 where the spectra of the same sample before and after the heating in vacuum are compared. The difference spectrum between the heated and not heated sample shows a clear maximum at 933 eV and this feature overlaps the high energy side of the white line. THE ELECTRONIC CONFIGURATIONThe spectra of YBa2CU306.5+x (x-0.4) and of the The difference spectrum in fig. 4 shows the lineshape of KCu(biuret)2 show a new feature at 933 eV and 933.7 eV the derivative of the white line which can be assigned to a respectively in comparison with bivalent Cu compounds. In very small energy shift of the white line induced by sample fig. 3 it is clear that in there is an reduction. This shift is in the expected direction but it is overlap between this broad feature at 933 eV and the white smaller than experimental resolution of 0.1 eV.line, while in the insulating KCu(biuret)2 compound they are In order to assign the final state configuration of the 933 completely separated by 3 eV. eV feature we have measured the spectrum of the Cu20

The reaction of bovine serum albumin (BSA) with [ trans-RuCl 4(Im)(dimethylsulfoxide)][ImH] (Im = imidazole) (NAMI-A), an experimental ruthenium(III) anticancer drug, and the formation of the respective NAMI-A/BSA adduct were investigated by X-ray absorption spectroscopy (XAS) at the sulfur and chlorine K-edges and at the ruthenium K- and L 3-edges. Ruthenium K and L 3-edge spectra proved unambiguously that the ruthenium center remains in the oxidation state +3 after protein binding. Comparative analysis of the chlorine K-edge XAS spectra of NAMI-A and NAMI-A/BSA, revealed that the chlorine environment is greatly perturbed upon protein binding. Only modest changes were observed in the sulfur K-edge spectra that are dominated by several protein sulfur groups. Overall, valuable information on the nature of this metallodrug/protein adduct and on the mechanism of its formation was gained; XAS spectroscopy turns out to be a very suitable method for the characterization of this kind of systems.

We investigated, for the first time, by using Energy Dispersive X-ray Diffraction, the structure of a new ternary cationic liposome formulated with dioleoyl trimethylammonium propane (DOTAP), 1,2-dioleoyl-3-phosphatidylethanolamine (DOPE) and cholesterol (Chol) (DDC) which has been recently found to have a selective high gene transfer ability in ovarian cancer cells. Our structural results provide a further experimental support to the widely accepted statement that there is not a simple and direct correlation between structure and transfection efficiency and that the factors controlling cationic lipid/DNA (CL-DNA) complexes-mediated gene transfer depend not only on the formulations of the cationic liposomes and their thermodynamic phase, but also significantly on the cell properties.

We used Fourier Transform Infrared Spectroscopy (FTIR) combined with flow cytometry to study the apoptosis and necrosis processes in Jurkat, a lymphocyte cell line. The apoptosis was induced in the cells by a chemical agent, the actinomycin D, while the necrosis was induced lowering the pH value to 4.2. The apoptotic events were analysed by flow cytometry (using annexin V and propidium iodide) and contemporary monitored by FTIR spectroscopy at different times after the treatment. This comparison allowed us to find in the IR spectrum, between 3000 cm −1 and 2800 cm −1 , a "marker band" of the apoptosis corresponding to the exposure of phosphatidylserine on the outer leaflet of the membrane. A marker of a specific cellular process obtained by using a non-destructive technique such as FTIR spectroscopy, has a great significance in the diagnostic medicine providing a tool for detecting pathologies in vivo.