In this review the latest developments regarding the use of self‐assembled copolymers for the fabrication of nanomaterials will be presented and their real potential evaluated. Most of the strategies reported so far are herewith classified under two main approaches: a) use of block copolymers as nanostructured materials, either “as they are” or through a selective isolation of one or more component blocks, and b) as templates for the synthesis of metallic or semiconducting nanomaterials. The problems of the orientation and large‐scale order of self‐organizing block copolymer mesophases will be also introduced, due to their importance as a route towards further improvements of the nanofabrication means.

Nature Publishing GroupCorma Canós, A.; Concepción Heydorn, P.; Boronat Zaragoza, M.; Sabater Picot, MJ.; Navas Escrig, J.; Yacaman, MJ.; Larios, E.... (2013). Exceptional oxidation activity with sizecontrolled supported gold clusters of low atomicity. Nature Chemistry. 5 (9) SummaryThe catalyticic activity of gold depends on particle size, with reactivity increasing as particle diameter decreases. Investigation of the trends in the subnanometer regime, where gold exists as small clusters of a few atoms, is now starting thanks to recent advances in synthesis and characterization techniques. An easy method to prepare isolated gold atoms supported on functionalized carbon nanotubes and their performance in the oxidation of thiophenol with O 2 are described. Single gold atoms are not active and they aggregate under reaction conditions into gold clusters of low atomicity, which show a catalytic activity comparable to that sulfhydryl oxidase enzymes. When clusters grow into larger nanoparticles, catalyst activity drops to zero.Theoretical calculations show that gold clusters are able to simultaneously activate thiophenol and O 2 , while larger nanoparticles become passivated by strongly adsorbed thiolates. The combination of an optimum for reactants activation and product desorption makes gold clusters excellent catalysts. Main TextGold has attracted wide interest as catalyst in the last years due to its unexpected activity and, specially, to its high selectivity in organic reactions. [1][2][3] The catalytic properties of gold depend on several factors that in some cases are intimately related:gold particle size and morphology, metal-oxide support interaction, oxidation state of the active sites, etc. 4-8 The influence of particle size has been extensively investigated, and a volcano type curve with a maximum in activity at an optimum diameter has been reported for CO oxidation, 7 alkane oxidation, 9 or propene epoxidation with O 2 and H 2 , 10 while in other cases an exponential increase in activity with decreasing particle size has been observed. 5,11,12 However, the trends in catalytic activity when the particle diameter While it appears that in order to control reactivity, the atomicity control of the gold clusters is crucial, the synthesis of size-selected metal clusters and their deposition over a solid support is a challenging task. 26 The wet-chemistry methods for preparing supported metal clusters involve the anchoring of well defined precursors to an adequate support, 27,28 followed by removal of the ligands by post-synthesis treatments, trying to prevent cluster agglomeration during these steps. 9,[29][30][31]32 Soft landing of monodisperse metal clusters grown in the gas phase and with precise size selection by mass spectrometry is a more straightforward method, but it requires sophisticated equipment, and the scaling up of the process is a major drawback. 20,23,33 In The chemical nature of these isolated atoms has been investigated by X-ray absorption spectroscopy (XAS) and X-ray photoelectron spe...

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The potential and benefits of nanoparticles in nanobiotechnology have been enthusiastically discussed in recent literature; however, little is known about the potential risks of contamination by accidental contact during production or use. Although theories of transdermal drug delivery suggest that skin structure and composition do not allow the penetration of materials larger than 600 Da, some articles on particle penetration into the skin have been recently published. Consequently, we wanted to evaluate whether metallic nanoparticles smaller than 10 nm could penetrate and eventually permeate the skin. Two different stabilized nanoparticle dispersions were applied to excised human skin samples using vertical diffusion cells. At established time points, solutions in receiving chambers were quantified for nanoparticle concentration, and skin was processed for light transmission and electron microscope examination. The results of this study showed that nanoparticles were able to penetrate the hair follicle and stratum corneum (SC), occasionally reaching the viable epidermis. Yet, nanoparticles were unable to permeate the skin. These results represent a breakthrough in skin penetration because it is early evidence where rigid nanoparticles have been shown to passively reach the viable epidermis through the SC lipidic matrix.