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A systematic energy dispersive X-ray reflectometry study of different ruthenium phtalocyanine (RuPc)(sub 2) thin films was performed in order to investigate their reactivity with the oxidizing NO(sub x) gas. A preliminary ex situ analysis, consisting of the comparison between the morphological parameters of different films, before and after the exposure to the gas, was performed.

Recently, it has been postulated that a primary importance of the pH is for accomplishing efficient lipid-mediated translocation of nucleic acids across the endosomal membrane into the cytosol for transport to the nucleus. With the aim of providing insight into the postulated correlation between transfection efficiency, phase evolution of lipoplexes upon acidification, and DNA release, we investigated the pH dependence of the structure of low efficiency 1,2-dioleoyl-3-trimethylammonium-propane-dioleoylphosphocholine/DNA and high efficiency 3β-[N-(N′,N′-dimethylaminoethane)-carbamoyl]-cholesterol-dioleoylphosphatidylethanolamine/DNA lipoplexes by high-resolution synchrotron small-angle x-ray diffraction, while the extent of DNA release was estimated by means of electrophoresis on agarose gels. Here we show that upon acidification from physiological to acidic values (as those characteristic of endosomes), (i) the lamellar structure of lipoplexes was preserved with a decrease in the one-dimensional DNA packing density, reflecting a pH-induced contraction of interfacial area of lipid head groups and (ii) DNA was not released from lipoplexes. Distinct levels of transfection between lipoplexes were interpreted in terms of the different DNA-binding capacities of cationic liposomes. [ABSTRACT FROM AUTHOR]

A systematic energy dispersive x-ray reflectometry study of different ruthenium phthalocyanine (RuPc)2 thin films was performed in order to investigate their reactivity with the oxidizing NOx gas. A preliminary ex situ analysis, consisting of the comparison between the morphological parameters of different films (before and after the exposure to the gas), was performed. It suggests that a reaction involving two different mechanisms takes place. The following in situ (while fluxing the gas) reflectometry analysis confirms this hypothesis, and clarifies the temporal evolution, also revealing that the first mechanism is limited to the film surface, while the second is a bulk diffusion process. [ABSTRACT FROM AUTHOR]