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The encapsulation of [Eu(dbm)3phen] into functionalized mesoporous silica nanoparticles (MSN) has been carried out to study the effect of chemical environments on the photoluminescence properties of the rare-earth complex. Surface functionalization was achieved by the reaction of the silanol groups on the surface of mesoporous silica with different organosilylating agents such as (3-aminopropyl)-triethoxysilane (APTES), (3-mercaptopropyl)-trimethoxysilane (MPTMS), and ethoxytrimethylsilane (ETMS). A change in the luminescence properties of the Eu(dbm)3phen complex has been observed on its encapsulation into surface modified mesoporous silica nanoparticles. The modification of photophysical properties is attributed to the interaction of Eu(dbm)3phen with the different chemical environments in the functionalized mesoporous silica nanoparticles (MSN). The luminescence properties of the rare-earth complex in surface-modified MSN increase in the order MSN < MSN-ETMS < MSN-MPTMS < MSN-APTES. The Eu(dbm)3phen complex encapsulated in the functionalized mesoporous silica nanoparticles shows an enhanced luminescence and an increased lifetime compared to the pure rare-earth complex in the solid state and that in unmodified MSN. This implies that some interactions of the lanthanide complexes take place during their incorporation process into the organically modified mesoporous silica nanoparticles. The organically modified mesoporous silica nanoparticles were characterized by Fourier transform infrared spectroscopy (FTIR) and N2 adsorption desorption measurements. The luminescence properties of the encapsulated Eu(dbm)3phen were studied in detail. Moreover, the effect of functionalized MSNs on the structural behaviour of the Eu(dbm)3phen was investigated by solid state nuclear magnetic resonance (SSNMR) techniques using an analogous diamagnetic model complex, Y(dbm)3phen, encapsulated into functionalized MSNs. These studies indicate that the encapsulated rare-earth complex shows some interactions with the functional groups anchored on the surface of MSNs. [ABSTRACT FROM AUTHOR]

Background: TiO2 nanoparticles (TiO2 NPs) are the nanomaterial most produced as an ultraviolet (UV) filter. However, TiO2 is a semiconductor and, in nanoparticle size, is a strong photocatalyst, raising concerns about photomutagenesis. Mesoporous silica nanoparticles (MSN) were synthetized incorporating TiO2 NPs (TiO2@MSN) to develop a cosmetic UV filter. The aim of this study was to assess the toxicity of TiO2@MSN, compared with bare MSN and commercial TiO2 NPs, based on several biomarkers. Materials and Methods: Human peripheral blood mononuclear cells (PBMC) were exposed to TiO2@MSN, bare MSN (network) or commercial TiO2 NPs for comparison. Exposed PBMC were characterized for cell viability/apoptosis, reactive oxygen species (ROS), nuclear morphology, and cytokines secretion. Results: All the nanoparticles induced apoptosis, but only TiO2 NPs (alone or assembled into MSN) led to ROS and micronuclei. However, TiO2@MSN showed lower ROS and cytotoxicity with respect to the P25. Exposure to TiO2@MSN induced Th2-skewed and pro-fibrotic responses. Conclusions: Geno-cytotoxicity data indicate that TiO2@MSN are safer than P25 and MSN. Cytokine responses induced by TiO2@MSN are imputable to both the TiO2 NPs and MSN, and, therefore, considered of low immunotoxicological relevance. This analytical assessment might provide hints for NPs modification and deep purification to reduce the risk of health effects in the settings of their large-scale manufacturing and everyday usage by consumers. [ABSTRACT FROM AUTHOR]

The development of new safe inorganic UV filters to effectively protect the skin from ultraviolet (UV) radiation effects is an emerging issue. Bismuth titanate-based UV filters embedded into mesoporous silica nanoparticles (MSN) represent a new class of inorganic sunscreens, with excellent UVA and UVB shielding properties. In addition, the presence of bismuth ions promotes a self-sealing process, allowing (i) the entrapment of the active phases in the deepest core of the system and (ii) the formation of an external glassy silica layer with a consequent suppression of the photocatalytic activity. In this work, aimed at studying in detail the self-sealing mechanism and accessing the role of bismuth ions in the formation of the system, a series of samples impregnated with a different amount of bismuth were investigated. The self-sealing process already occurs at the lowest content of bismuth and the mechanism is demonstrated to be triggered by the ability of Bi to work as a low-melting point agent for silica. Finally, a sunscreen formulation containing the new UV filter was prepared and the Sun Protection Factor (SPF), the pH and the viscosity were measured, demonstrating the potential of the proposed material for large-scale applications. [ABSTRACT FROM AUTHOR]

Abstract: Ordered mesoporous silica nanoparticles (MSNs) were impregnated with different loadings of the luminescent complex tris(dibenzoylmethane) mono(1,10-phenanthroline)europium(III) (Eu(dbm)3phen), with the aim of increasing the luminescence by avoiding concentration quenching and having mainly in mind the application as spectral converter for multi-crystalline silicon solar cells. The morphological, structural and luminescence properties of the impregnated silica nanoparticles were characterized by N2 physisorption, X-ray diffraction, transmission electron microscopy, infrared spectroscopy, UV–visible spectroscopy and photoluminescence excitation and emission measurements. Photostability was tested under 1 sun (1000W/m2) illumination for 24h and the related effects were inspected by UV–visible and photoluminescence spectroscopies. Impregnation of the complex into 50–70nm MSNs with pore size tailored around 2.9nm depressed concentration quenching and allowed the use of complex loadings as high as 23wt%. Sunlight irradiation caused a marked increase in the luminescence intensity. [Copyright &y& Elsevier]

[Display omitted] • Silica nanoparticles of 50 and 120 nm have been synthetized by Stöber method and dispersed at 5% in an ethanol:water solution. • The chemical compatibility between silica nanoparticles and silicate stones was guaranteed. • No significant colour and morphological alterations appeared on treated surfaces after the application of the strengthening agent. • A certain reduction of water absorbed was demonstrated. • Aggregation tendency of SNP when in contact with water was observed. • The formation of SNP clusters developed structures with dimensions higher than those of porous diameters impeding sometimes the penetration of the treatment. The application of silica nanoparticles strengthening agents in conservation of monumental and architectural heritage field is currently a challenge of particular interest. Some commercial products are already on the market and several studies highlighted the related strength and weakness. In order to contribute to the knowledge of the interaction between nanoparticles and stone materials as well as to provide key elements to improve the approach to conservative treatments, two silica nanoparticles products for the consolidation of silicate stones were developed in the laboratory. Bianco Sardo granite, Firenzuola and Muggia sandstones were selected as substrates for the experimentation after a laboratory investigation of their open porosity. Silica nanoparticles having two different particles size, both compatible with the porosimetric features of the selected stones, were synthesized and dispersed in an ethanol–water solution. The carrier was specifically studied for avoiding the agglomeration of silica nanoparticles and facilitating the penetration of the products in the stone substrates. Sound and artificially aged specimens were impregnated by capillary absorption method and the effectiveness of the treatment was evaluated through morphological and physical analyses. Microscopic observations, colorimetric analyses, sponge tests, ultrasound velocity determinations and porosimetric measurements showed positive results, which encourage, on one hand, the use of silica nanoparticles for consolidating silicate stones, on the other hand, further researches aimed to improve the synthesized products by reaching a deeper penetration and the reduction of water absorption. [ABSTRACT FROM AUTHOR]