The flavonoid quercetin is extensively studied for its antioxidant and chemopreventive properties.However the poor water-solubility, low stability and short half-life could restrict its use in skin care products and therapy.The present study is aimed to evaluate the potential of aminopropyl functionalized mesoporous silica nanoparticles (NH 2 -MSN) as topical carrier system for quercetin delivery. Thermo gravimetric analysis, X-ray diffraction, high resolution transmission electron microscopy, nitrogen adsorption isotherms, FT-IR spectroscopy, zeta potential measurements and differential scanning calorimetry allowed analyzing with great detail the organic-inorganic molecular interaction.The protective effect of this vehicle on UV-induced degradation of the flavonoid was investigated revealing a certain positive influence of the inclusion on the photostability over time.Epidermal accumulation and transdermal permeation of this molecule were ex vivo evaluated using porcine skin mounted on Franz diffusion cells. The inclusion complexation with the inorganic nanoparticles increased the penetration of quercetin into the skin after 24 h post-application without transdermal delivery.The effect of quercetin alone or given as complex with NH 2 -MSN on proliferation of JR8 human melanoma cells was evaluated by sulforhodamine B colorimetric proliferation assay. At a concentration 60 M the complex with NH 2 -MSN was more effective than quercetin alone, causing about 50% inhibition of cell proliferation.

In this work we report the synthesis of new fluorescent analogues of strigolactones, their spectroscopic properties and the evaluation of their biological activity both on seeds of Orobanche aegyptiaca and on the AM fungus Gigaspora margarita. The synthesis has been accomplished according to two different synthetic plans and allows the introduction of various substituents on the A and C rings of the framework, thus enabling access to bioactive molecules with different spectroscopic properties.

No abstract

Electronic absorption and fluorescence spectra based on transmission measurements of thin layers obtained from new perylene−zeolite L composites and new dye1,dye2−zeolite L sandwich composites, the latter acting as antenna systems, have been investigated and analyzed. The influence of extra-and intraparticle self-absorption on the spectral shape and fluorescence quantum yield is discussed in detail. Due to its intraparticle origin, self-absorption and re-emission can often not be avoided in organized systems such as dye−zeolite L composites where a high density of chromophores is a prerequisite for obtaining the desired photophysical properties. We show, however, that it can be avoided or at least minimized by preparing dye1,dye2−zeolite L sandwich composites where donors are present in a much larger amount than the acceptors because they act as antenna systems. ■ INTRODUCTIONComposites synthesized by embedding molecules, complexes, and clusters into the one-dimensional channels of zeolite L (ZL) 1,2 have recently experienced increasing interest from scientists engaged in different fields, ranging from very stable nontoxic pigments to novel optical materials with a large variety of different properties to promising objects for utilization in analytics, biology, diagnostics and drug delivery. This trend is exemplified by publications that appeared in 2013. 3−16 Electronic absorption and luminescence spectroscopy are important tools for characterizing the host−guest composites, and luminescence is often one of their key properties. Confocal luminescence microscopy on individual crystals has successfully been used and has contributed much to our current understanding of various dye−ZL properties. 17−23 It is very often desirable to measure absorption and luminescence spectra of an ensemble in order to unambiguously interpret the observations and sometimes to derive luminescence quantum yields. Diffuse reflectance spectroscopy has frequently been used in the case for which this sophisticated instrumentation has been developed. 10,24 Advancing dye−ZL research requires measurements that not only yield spectra and quantum yields as numbers but also provide information useful for understanding the mechanisms behind the observed phenomena. A prerequisite for these are high quality absorption and luminescence spectra where the band shapes can be interpreted unambiguously. This is best guaranteed if high quality transmission spectra are available. We have therefore successfully applied refractive index matching techniques in order to reduce or in favorable cases eliminate light scattering. We have used dispersions in liquid solvents or polymers as matrixes for dye−ZL composites, where sometimes a surface modification of the ZL crystals was required.25−27 More recently, a method for the preparation of thin oil−glass sandwiches (OGS) from dye−ZL composites has been employed. 15,20 This technique has proven to be very convenient and allows differentiating between mechanisms that affect the shape of the absorptio...

No abstract

No abstract

Spherical hybrid cyanine-silica nanoparticles, quite homogeneous in size (ca. 50 nm) were prepared by the reverse microemulsion method. Solvatochromism tests indicated that all fluorophore molecules were actually entrapped within the inorganic matrix. The combination of steady-state and time-resolved fluorescence measurements allowed us to conclude that almost all cyanine molecules exhibited the same photophysical behavior and this suggested they should be dispersed in a monomeric form. Such behavior resulted in a significant brightness enhancement per cubic nanometer of nanoparticle with respect to molecules in solution. The occurrence of the optical interparticle effect by progressively decreasing the distance among hybrid nanoparticles passing from suspension to a dry powder was also investigated.

Using a distinctive bottom-up approach, hierarchical SAPO-34 has been synthesized using CTAB encapsulated within ordered mesoporous silica (MCM-41) that serves as both the silicon source and mesoporogen. The structural and textural properties of the hierarchical SAPO-34 were contrasted against its microporous analogue, and the nature, strength and accessibility of the Brønsted acid sites were studied using a range of physicochemical characterization tools; notably probe-based FTIR and solid-state (SS) MAS NMR. Whilst CO was used to study the acid properties of hierarchical SAPO-34, bulkier molecular probes (including pyridine, 2,4,6-trimethylpyridine and 2,6-di-tert-butylpyridine) allowed particular insight into the enhanced accessibility of the acid sites. The activity of the hierarchical SAPO-34 catalyst was evaluated in the industrially-relevant, acid-catalysed Beckmann rearrangement of cyclohexanone oxime to ε-caprolactam, under vapor-phase conditions. These catalytic investigations revealed a significant enhancement in the yield of ε-caprolactam using our hierarchical SAPO-34 catalyst compared to SAPO-34, MCM-41, or a mechanical mixture of these two phases. The results highlight the merits of our design strategy for facilitating enhanced mass transfer, whilst retaining favorable acid site characteristics.