Raman Scattering Study of Natural and Synthetic Compounds Containing Polyene Chains

Doklady Physics - The dependence of Raman spectra of the molecules containing polyene chains on the conjugation length, structure of side and end groups, and isomer type is analyzed theoretically.     

Cosmetic Formulations with Melaleuca alternifolia Essential Oil for the Improvement of Photoaged Skin: A Double-Blind,Randomized, Placebo-Controlled Clinical Study

This aim of this study was to evaluate the penetration depth, antioxidant capacity and the clinical efficacy of Melaleuca alternifolia pure essential oil and in a nanoemulsion to prevent skin photoaging. For this, 2% of pure essential oil or 2% of this essential oil in a nanoemulsion were vehiculated in a formulation. The skin penetration was evaluated using confocal Raman microspectroscopy. The radical protection factor was evaluated using electron paramagnetic resonance spectroscopy. For a clinical study, 40 male participants, aged 18–28 years, were enrolled, being divided into three groups: vehicle formulation, M. alternifolia pure essential oil and M. alternifolia Nanoemulsion. All the participants also received a sunscreen SPF 50 to use during the day. Before and after 90 days of study, skin hydrolipidics and morphological characteristics were performed by skin imaging and biophysical techniques. The nanoemulsion presented a lower antioxidant capacity and a higher penetration through the stratum corneum, reaching the viable epidermis, improving the stratum granulosum morphology. The groups presented an increase in the papillary depth, improving in the dermis echogenicity and the collagen fibers. Melaleuca alternifolia essential provides the potential to improve photoaged skin, being the application of nanoemulsion able to reach deeper skin layers.     

The Effectiveness of Glycerol Solutions for Optical Clearing of the Intact Skin as Measured by Confocal Raman Microspectroscopy

Optics and Spectroscopy - The effect of glycerol solutions of different concentrations and exposure times on the optical clearing efficiency in intact pig skin has been studied in the analysis of...     

Investigation of InSb(1 1 0) and InSb(1 1 1) surfaces by means of target current (VLEED) spectroscopy and LEED

In this paper, we present experimental results of target current (TCS) and LEED investigation of well-oriented InSb(1 1 0) and InSb(1 1 1)-A and InSb(1 1 1)-B crystals. TCS results are interpreted in terms of very low electron diffraction (VLEED) and empty band signatures. To examine to which extent the TCS spectra reflect the bulk or surface electronic properties of InSb(1 1 0), thin layers of indium have been evaporated and the corresponding spectrum changes have been investigated.     

Advantages of NIR radiation use for optical determination of skin horny layer thickness with embedded TiO2 nanoparticles during tape stripping procedure

The tape stripping technique is an experimental method frequently used for reconstruction of the in-depth distribution of various topically administered substances within the horny layer of human skin, e.g., compounds contained in sunscreens. Titanium dioxide (TiO₂) nanoparticles (25–200 nm in diameter) are one such compound. Optical techniques which apply blue light are found to be suitable for reconstruction. However, the presence of particles affects the light propagation within the skin and therefore causes incorrect determination of strip thickness, leading to an improper reconstructed distribution of nanoparticle concentration revealed from the experimental data. This study evaluates the errors emerging from the use of blue (400 nm) and NIR (800 nm) radiation and finds the use of longer wavelength light more advantageous. Particles of different diameters are considered, and it is revealed that the application of small particles (25–60 nm) results in the lowest rate of error.     

Surface functionalization of silica nanoparticles supports colloidal stability in physiological media and facilitates internalization in cells

The influence of the surface functionalization of silica particles on their colloidal stability in physiological media is studied and correlated with their uptake in cells. The surface of 55 ± 2 nm diameter silica particles is functionalized by amino acids or amino- or poly(ethylene glycol) (PEG)-terminated alkoxysilanes to adjust the zeta potential from highly negative to positive values in ethanol. A transfer of the particles into water, physiological buffers, and cell culture media reduces the absolute value of the zeta potential and changes the colloidal stability. Particles stabilized by L-arginine, L-lysine, and amino silanes with short alkyl chains are only moderately stable in water and partially in PBS or TRIS buffer, but aggregate in cell culture media. Nonfunctionalized, N-(6-aminohexyl)-3-aminopropyltrimethoxy silane (AHAPS), and PEG-functionalized particles are stable in all media under study. The high colloidal stability of positively charged AHAPS-functionalized particles scales with the ionic strength of the media, indicating a mainly electrostatical stabilization. PEG-functionalized particles show, independently from the ionic strength, no or only minor aggregation due to additional steric stabilization. AHAPS stabilized particles are readily taken up by HeLa cells, likely as the positive zeta potential enhances the association with the negatively charged cell membrane. Positively charged particles stabilized by short alkyl chain aminosilanes adsorb on the cell membrane, but are weakly taken up, since aggregation inhibits their transport. Nonfunctionalized particles are barely taken up and PEG-stabilized particles are not taken up at all into HeLa cells, despite their high colloidal stability. The results indicate that a high colloidal stability of nanoparticles combined with an initial charge-driven adsorption on the cell membrane is essential for efficient cellular uptake.     

Influence of IR radiation on the carotenoid content in human skin

It is shown that the infrared irradiation decreases the content of β-carotene and lycopene carotenoids in human skin. A decrease in the content of β-carotene and lycopene may indicate that the IR radiation, as well as the UV radiation, is capable of forming free radicals in human skin. The investigations were performed in vivo using the technique of resonance Raman scattering developed by us for the noninvasive determination of antioxidant potential in skin.     

Radical Protection by Differently Composed Creams in the UV/VIS and IR Spectral Ranges

Modern sunscreens are well suited to provide sufficient protection in the UV range because the filter substances absorb or scatter UV radiation. Although up to 50% of radicals are formed in the visible and infrared spectral range during solar radiation protection strategies are not provided in this range. Previous investigations of commercially available products have shown that in addition to physical filters, antioxidants (AO) are necessary to provide protective effects in the infrared range by neutralizing already formed radicals. In this study, the efficacy of filter substances and AO to reduce radical formation in both spectral ranges was investigated after UV/VIS or IR irradiation. Optical properties and radical protection were determined for the investigated creams. It was found that organic UV filters lower radical formation in the UV/VIS range to 35% compared to untreated skin, independent of the presence of AO. Further reduction to 14% was reached by addition of 2% physical filters, whereas physical filters alone were ineffective in the UV/VIS range due to the low concentration. In contrast, this filter type reduced radical formation in the IR range significantly to 65%; similar effects were aroused after application of AO. Sunscreens which contain organic UV filters, physical filters and AO ensure protection in the complete solar spectrum.     

Einige Reaktionen mit [Mo6Cl8]Cl4

Some Reactions with [Mo₆Cl₈]Cl₄ The reaction of [Mo₆Cl₈]Cl₄ with different chemical agents has been investigated: The methoxylation depends on the CH₃O^? concentration in CH₃OH. The reaction with HF leads to a partial fluorinated [Mo₆Cl₈] product. With NH₄F (NH₄)₂[Mo₆Cl₈]F₆ in formed, the hydrolysis of which leads to [Mo₆Cl₈]F₃(OH) · 2.5 H₂O. This compound can be decomposed thermically into [Mo₆Cl₈]O₂. [Mo₆Br₈]F₆^2? on hydrolysis leads to [Mo₆Br₈]F₃(OH) · 5 H₂O. With CsF Cs₂[Mo₆Cl₈]F₆ is formed, which by hydrolysis is transformed into [Mo₆Cl₈]F₃(OH) · 2.5 H₂O and possibly to [Mo₆Cl₈]F₄ · xH₂O(?). In reaction of [Mo₆Cl₈]Cl₄ with H₂SO₄ one gets [Mo₆Cl₈](SO₄)₂. Salts e. g. [(C₆H₅)₄As]₂[Mo₆Cl₈](OC₆F₅)₆ and adducts e. g. [Mo₆Cl₈](OC₆F₅)₄ · 2 HMPA are prepared. The compounds have been characterized by X-ray powder-diagramms and by IR-spectra.     

Analysis of the penetration of a caffeine containing shampoo into the hair follicles by in vivo laser scanning microscopy

In previous in vitro investigations, it was demonstrated that caffeine is able to stimulate the hair growth. Therefore, a penetration of caffeine into the hair follicle is necessary. In the present study, in vivo laser scanning microscopy (LSM) was used to investigate the penetration and storage of a caffeine containing shampoo into the hair follicles. It was shown that a 2-min contact time of the shampoo with the skin was enough to accumulate significant parts of the shampoo in the hair follicles. A penetration of the shampoo up to a depth of approx. 200 μm could be detected, which represents the detection limit of the LSM. At this depth, the close network of the blood capillaries surrounding the hair follicles commences. Even after 24 h, the substance was still detectable in the hair follicles. This demonstrates the long-term reservoir function of the hair follicles for topically applied substances such as caffeine.