M.C.A. Fantini

Reverse Hexagonal Phase Nanodispersion of Monoolein and Oleic Acid for Topical Delivery of Peptides: in Vitro and in Vivo Skin Penetration of Cyclosporin A

PurposeTo obtain and characterize reverse hexagonal phase nanodispersions of monoolein and oleic acid, and to evaluate the ability of such system to improve the skin penetration of a model peptide (cyclosporin A, CysA) without causing skin irritation.MethodsThe nanodispersion was prepared by mixing monoolein, oleic acid, poloxamer, and water. CysA was added to the lipid mixture to obtain a final concentration of 0.6% (w/w). The nanodispersion was characterized; the skin penetration of CysA was assessed in vitro (using porcine ear skin mounted in a Franz diffusion cell) and in vivo (using hairless mice).ResultsThe obtainment of the hexagonal phase nanodispersion was demonstrated by polarized light microscopy, cryo-TEM and small angle X-ray diffraction. Particle diameter was 181.77 ± 1.08 nm. At 0.6%, CysA did not change the liquid crystalline structure of the particles. The nanodispersion promoted the skin penetration of CysA both in vitro and in vivo. In vitro, the maximal concentrations (after 12 h) of CysA obtained in the stratum corneum (SC) and in the epidermis without stratum corneum (E) + dermis (D) were ∼2 fold higher when CysA was incorporated in the nanodispersion than when it was incorporated in the control formulation (olive oil). In vivo, 1.5- and 2.8-times higher concentrations were achieved in the SC and [E+D], respectively, when the nanodispersion was employed. No histopathological alterations were observed in the skin of animals treated with the nanodispersion.ConclusionThese results demonstrate that the hexagonal phase nanodispersion is effective in improving the topical delivery of peptides without causing skin irritation.

On the nitrogen and oxygen incorporation in plasma-enhanced chemical vapor deposition (PECVD) SiOxNy films

Silicon oxynitride films were deposited by plasma-enhanced chemical vapor deposition at low temperatures using nitrous oxide (N2O) and silane (SiH4) as gas precursors. The influence of the N2O/SiH4 flow ratio (varied from 0.25 up to 5) and the thickness of the films on the optical and structural properties of the material was analyzed. The films were characterized by ellipsometry, Fourier-transform infrared spectroscopy, Rutherford backscattering spectroscopy and optical absorption. Two distinct types of material were obtained, silicon dioxide-like oxynitrides SiO2−xNx and silicon-rich oxynitrides SiOxNy (x+y<2). The results demonstrate that in silicon dioxide-like material, the nitrogen concentration can be adequately controlled (within the range 0–15 at.%) with total hydrogen incorporation below 5 at.% and no appreciable SiH bonds. It is also shown that the composition remains uniform through the entire thickness of the films. Furthermore, a linear relation between the refractive index and the nitrogen concentration is observed, which makes this material very attractive for optoelectronic applications. On the other hand, silicon-rich material is similar to amorphous silicon, and presents an increasing concentration of SiH bonds, increasing refractive index and decreasing optical gap, which makes it promising for applications in light-emitting devices.

Electrochromic nickel oxide thin films deposited under different sputtering conditions

Abstract In this work, non stoichiometric nickel oxide (NiO x ) thin films were deposited by r.f. reactive sputtering of a metallic nickel target in an O 2 -Ar atmosphere. A systematic variation of two deposition parameters was done: the oxygen flux (φ) and the r.f. power ( P ). The electrochemical characterization of the films was performed in aqueous electrolyte. The spectral transmittance measurements, as well as the X-ray diffraction analysis were performed ex-situ, while monochromatic transmittance and stress measurements were performed in situ. Samples deposited at low oxygen flux (or high power) are transparent, in contrast to those deposited at high oxygen flux (or low power), which are dark brown. The films were cubic NiO, with preferred orientation in the (111) direction. Lattice parameters increase with increasing oxygen flux during deposition, but decrease with increasing power. For all samples, the ratio O Ni was greater than 1, as determined by Rutherford back-scattering analysis. Also, an important hydrogen content was found in the films. The relationship between optical, electrochemical, mechanical, structural and morphological behaviour of the above mentioned films will be reported and discussed in this work.

Immunological parameters related to the adjuvant effect of the ordered mesoporous silica SBA-15

In 2006, the first report of a nanostructured material as adjuvant was described establishing the effectiveness of the ordered mesoporous SBA-15 silica as an immune adjuvant. The present study evaluated the SBA-15 capacity to modulate the immune responsiveness of High and Low responder mice immunized with BSA encapsulated/adsorbed in SBA-15 by the intramuscular or oral route and the adjuvant effect was compared with the responsiveness induced by BSA in aluminum hydroxide salts or emulsified in Incomplete Freund adjuvant. These results demonstrate the ability of the non-toxic SBA-15 nanoparticles to increase the immunogenicity and repair the responsiveness of the constitutively low responder individuals inducing both the IgG2a and the IgG1 isotypes, independently of the immune cell committed and conditioning the low phenotype. This new adjuvant may reveal novel therapeutic targets for immune modulation and vaccine design.

Radio frequency sputtered cobalt oxide coating : structural, optical and electrochemical characterization

Cobalt oxide thin films (thickness 2000 A) with different stoichiometries were deposited by reactive rf sputtering. The variation of the oxygen partial pressure lead to films with compositions varying from metallic cobalt to CO3O4, as determined by x‐ray diffraction and x‐ray photoelectron spectroscopy. The electrochromic properties of the films were investigated in aqueous electrolytes (0.1 M KOH). The initial electrochemical behavior of the films is strongly dependent on the film deposition conditions, but after cycling the electrochemical/electrochromic characteristics of the different deposits were quite similar. Transmittance changes and electrochromic efficiency are discussed.

The influence of “starving plasma” regime on carbon content and bonds in a-Si1−xCx:H thin films

Differences on carbon content and chemical bonds in a-Si1−xCx:H were observed and analyzed in carbon rich and silicon rich films, deposited by plasma enhanced chemical vapor deposition from mixtures of silane and methane. The influence of the radio frequency low power density regime on the film’s properties was investigated. The content of Si, C, and H in the solid phase was obtained by Rutherford back scattering and forward recoil spectrometry. The bondings were analyzed by Fourier transform infrared spectroscopy. Quantitative analysis on the film’s chemical composition was performed combining the vibrational spectra with the stoichiometry data. The results showed that under “silane starving plasma” conditions, a carbon content as high as 70 at. % is achieved and the main carbon bonds are tetragonal C–H,  C–H2, and Si–C.

Local structure and bonds of amorphous silicon oxynitride thin films

Abstract This work reports on the local structure and bonds of amorphous silicon oxynitride thin films, deposited by plasma enhanced chemical vapor deposition. The dependence of the structural properties and chemical bonds with the films composition was investigated. The used analytical techniques were X-ray absorption at the Si K-edge and Fourier transform infrared spectroscopies. The coordination numbers, interatomic distances and Debye–Waller disorder factors of the Si first shell and, the bond types and the concentration of hydrogen in the films were obtained. All the analyzed data support the formation of a materials homogeneous network with a random distribution of SiO and SiN bonds. The basic structural element of the network is a tetrahedron with a central Si atom connected to N and O, consistent with a random bonding model. As the nitrogen content in the solid phase decreases the SiON 3 , SiO 2 N 2 tetrahedral units gradually change to SiO 4 , keeping the quantity of SiO 3 N tetrahedrons almost unchanged, approximately 40%. The amount of SiO 4 units is 100% for films with high oxygen content. The nitrogen is preferentially bonded to silicon and hydrogen, while the hydrogen is mostly bonded to nitrogen.

Synthesis, characterization and electrochromic properties of NiOxHy thin film prepared by a sol–gel method

Abstract In this work, sol–gel and dip-coating methods were used to produce nickel oxide/hydroxide films. Strips of glass previously coated with transparent/conducting films of SnO 2 were utilized as substrates. The nickel oxide films were obtained by wetting the substrates in a solution of NiCl 2 ·6H 2 O in butanol and ethylene glycol. The dried gel films were found to be transparent and moisture sensitive. X-ray diffraction analysis (XRD) was performed to identify the produced compounds of heat-treated samples. A significant effect of temperature and time on the films thickness was observed. Simultaneously, chemical analysis, e.g. carbonaceous matter and water, were examined by DSC and FTIR spectroscopy. Transmittance measurements were performed in the range of 350 nm to 850 nm in the films at different optical states. The coloration/bleaching process was found to be reversible. The cyclic voltammetry shows broad peaks related to Ni(II)/Ni(III) and Ni(III)/Ni(IV) oxidation/reduction processes. The measurements are discussed in detail in terms of the temperature effect.

Theoretical and experimental results on Au-NiO and Au-CoO electrochromic composite films

Abstract This paper reports on the theoretical calculations and experimental results on the optical properties, between 400 and 1000 nm, of Au–NiO and Au–CoO composite films. The calculations were based on the Maxwell Garnett effective medium theory, with Au fill factors f varying from 0.0 to 0.05. The results for both media are very similar. The Au configuration in the insulating matrix was modeled to be isolated single spheres (ISS), single linear chain (SLC) and fcc cluster (FCC), as examples of selective absorption in these composite films. Variations in transmission and reflection can be obtained either by thickness variation, as well as from Au incorporation, as seen from theoretical and experimental results. Au–NiO films with different reflected colors (blue, green, yellow and orange-red) and same Au content were obtained by varying the pressure inside the sputtering deposition chamber. Green colored Au–CoO films with different Au content were deposited.

Lithium insertion and electrochromism in polycrystalline molybdenum oxide films

In this work, molybdenum oxide thin films were deposited by r.f. reactive sputtering of metallic molybdenum target in an Ar + O 2 atmosphere. Thin films with different compositions and crystal structures were obtained by varying the oxygen flow (o). All samples, with the exception of the MoO 2 film, showed an electrochromic behavior, due to the reversible Li + /e insertion or extraction process. The transmittance change (λ = 632.8 nm), for the best sample, was ∼ 70%. The film having the best optical behavior is mostly formed by the β-MoO 3 phase. The composition, optical and mechanical properties were determined and analyzed in as-grown and in Li intercalated films. The local order structure was analyzed by X-ray absorption spectroscopy measurements at the Mo L 2,3 -edges. The valence band was studied by Photoelectron Spectroscopy.