New Insight into the Chemical Nature of the Plasmonic Nanostructures Synthesized by the Reduction of Au(III) with Sulfide Species.

We have studied the products of the controversial synthesis of HAuCl4 with Na2S, which include gold nanostructures (Au NSs) that absorb in the near-infrared (NIR) region and are highly promising for photothermal therapies and other nanomedical applications. From high-resolution transmission electron microscopy, X-ray absorption spectroscopy, and small-angle X-ray scattering, we have found that only metallic Au NSs are formed as a result of this synthesis, with no detectable amount of gold sulfide or other oxidized gold species that could account for the NIR absorption. Different sulfur species are adsorbed on the Au NSs, mainly sulfides (monomeric sulfur) and polysulfides, similar to what is found on the planar gold surfaces, therefore precluding the idea that thiosulfate or other oxidized species are the actual reducing agents for Au(III) ions. The presence of strongly adsorbed S species, which are difficult to remove from the gold surface, is of great importance for their applications as regards toxicity and use of postfunctionalization strategies to anchor biomolecules and/or to increase circulation time after administration.

Synthesis of water-soluble gold clusters in nanosomes displaying robust photoluminescence with very large Stokes shift.

This paper reports a novel procedure using nanosomes, made of bola-hydroxyl and mercapto-palmitic acids, for the production of gold clusters with robust luminescent emissions and very large Stokes shifts. It shows that these results cannot be explained by the currently accepted mechanism based on ligand-to-metal charge transfer absorptions involving electron-rich ligands attached to the cluster core. Exhaustive characterization of the cluster samples using Mass Spectrometry, HR-TEM/STEM, XPS, EXAFS, and steady-state and time-resolved luminescence allows to deduce that a mixture of two cluster sizes, having non-closed shell electronic configurations, are firstly generated inside the nanosome compartments due to the difference in bonding strength of the two types of terminal groups in the fatty acids. This initial bimodal cluster size distribution slowly evolves into very stable, closed-shell Au cluster complexes (Au6-Au16 and Au5-Au14) responsible for the observed luminescent properties. The very small (≈1.2 nm) synthesized cluster complexes are water soluble and suitable to be used for the conjugation of biomolecules (through the terminal COO(-) groups) making these systems very attractive as biomarkers and offering, at the same time, a novel general strategy of fabricating stable atom-level quantum dots with large Stokes shifts of great importance in many sensor applications.

Controlled growth of extended arrays of CoSi2 hexagonal nanoplatelets buried in Si(001), Si(011) and Si(111) wafers.

Because of their high electrical conductivity CoSi2 nanostructures are potential candidates for preparing ordered nano-arrays to be used as electrode interconnectors and contacts in microelectronic devices. We here describe a controlled procedure for the endotaxial growth of hexagonal CoSi2 nanoplatelets buried in differently oriented single crystalline Si wafers on which a Co-doped SiO2 thin film was previously deposited. These nanomaterials were obtained by a clean procedure consisting of isothermal annealing at 750 °C under a He atmosphere of Co-doped SiO2 thin films deposited onto the surface of three differently oriented flat Si substrates, namely Si(001), Si(011) and Si(111). Buried CoSi2 nanoplatelets are in all cases spontaneously formed as a consequence of the diffusion of Co atoms into the silicon wafer and their reaction with host Si atoms. Our TEM and GISAXS analyses demonstrated that these arrays, irrespective of host Si orientation, consist of CoSi2 hexagonal nanoplatelets in all cases parallel to Si{111} crystallographic planes. Additionally, the dimensions of the nanoplatelets were consistently determined by TEM and GISAXS for the three different host Si single crystal orientations.

Aminopropyl-modified mesoporous silica SBA-15 as recovery agents of Cu(II)-sulfate solutions: Adsorption efficiency, functional stability and reusability aspects.

Hybrid mesoporous materials are potentially useful for metal ion scavenging and retrieval because of their high surface areas, controlled accessibility and tailored functionalization. Some aspects that are linked to the performance of HMM include pore accessibility, stability of the organic functions and reusability. Knowledge of these aspects is critical in the design of adsorption-desorption protocols. In this work we produce and characterize propylamino-substituted large pore silica (SBA-15-N), which is submitted to Cu(II) adsorption from copper sulfate solutions, followed by desorption in acid media and material regeneration. We find that the hybrid material is an efficient adsorbent (1.15-1.75mmol Cu(II)g(-1)), although a fraction of the organic groups is lost during the adsorption process. An X-ray photoelectron spectroscopy (XPS) study demonstrates that the contents of amino groups are higher in the material surface, leading to different behaviors in Cu(II) complexation along the material. These materials can be regenerated by exposure to acidic media. Thermal processing of the hybrid materials leads to better durability in aqueous solutions during reprocessing, due to enhanced polycondensation of the inorganic framework. Thermally treated samples, once regenerated, are efficient adsorbents in a second step of Cu(II) adsorption. We discuss the materials processing factors involved in the improved adsorption of Cu(II), its quantitative release and reusability of the material.

"Naked" gold nanoparticles supported on HOPG: melanin functionalization and catalytic activity.

Reductive electrodesorption has been used to produce "naked" gold nanoparticles (AuNPs) 3 nm in size on HOPG from different thiolate-capped AuNPs. The clean AuNPs transform the electrocatalytic inert HOPG into an active surface for hydrogen peroxide electroreduction, causing a lowering of the cathodic overpotential of 0.25 V with respect to the Au(111) surface. Compared to the plain gold substrates, the nanostructures promote only a slight increase in the hydrogen evolution reaction. In a second modification step a ∼1 nm thick melanin-iron coating is electrochemically formed around the AuNPs. This ultrathin melanin-iron coating largely improves the catalytic activity of the bare AuNPs for both hydrogen peroxide electroreduction and hydrogen evolution reaction. This strategy, which integrates electrochemistry and nanotechnology, can be applied to the preparation of efficient "naked" AuNPs and organic-iron capped AuNPs catalysts.

Structure of extremely nanosized and confined In-O species in ordered porous materials.

Perturbed-angular correlation, x-ray absorption, and small-angle x-ray scattering spectroscopies were suitably combined to elucidate the local structure of highly diluted and dispersed InOx species confined in the porous of the ZSM5 zeolite. This novel approach allow us to determined the structure of extremely nanosized In-O species exchanged inside the 10-atom-ring channel of the zeolite, and to quantify the amount of In2O3 crystallites deposited onto the external zeolite surface.

In situ and ex situ XANES study of nanodispersed Mo species in zeolites used in fine chemistry catalysis.

Mo K-edge XANES experiments on Mo-containing zeolites at low Mo loading (1 and 2 wt% of Mo on H-ZSM-11, H-BETA and H-ZSM-5 catalysts), active in fine chemistry reactions, were performed ex situ as function of sample calcination temperature in air (in the range 773-973 K) or in situ at 873 and 973K under N2 flow. The results showed a 4-fold oxygen coordination for the incorporated Mo species in the activated (dehydrated) state. Combining these results with additional data evidences an almost total Mo exchange inside the zeolite channels.

The two-in-one model: a new variation of the arteriovenous malformation model in swine.

We report a new variation of the well-established experimental arteriovenous malformation (AVM) model in swine. To provide high flow through the rete mirabile (nidus, RM) and thereby to reduce the rate of spontaneous thrombosis of the AVM, we performed an end-to-end anastomosis of the left common carotid artery (CCA) and the external jugular vein (EJV) microsurgically in three micropigs. After 1 and 4 months the animals underwent angiograms of the CCA and vertebral artery (VA). In all cases the diversion of the blood through the RM was patent, up to the 4 months follow-up. We observed an arteriovenous fistula (arteriovenous pseudomalformation, pAVF) between the VA and the EJV in each case at both 1 and 4 months. This modification of the well-known AVM model in the micropig could be used to monitor long-term changes after embolisation, avoiding the naturally high rate of spontaneous thrombosis. This two-in-one model is thus well suited for preclinical testing of embolic materials.

Arteriovenous malformation model in Swine: a natural history study: preliminary results.

SUMMARY: The well-known porcine arteriovenous malformation (AVM) model introduced by Massoud et al has been widely used as an acutephase model. However, there are no data available on the patency rate in long-term follow-up. Therefore this study is dedicated to the natural history of porcine AVM model after creation. Three piglets (Yucatan micropigs, aged 12 to 14 months) were used in this study. The model was created by microsurgical anastomosis in an end-to-end fashion between the common carotid artery (CCA) and external jugular vein (EJV) on the left side, and by direct ligation of the left external carotid artery (ECA). Angiography was performed before and immediately after model creation, as well as at 44, 103, 188 and 245 days in all animals. A successful high-flow brain AVM model was established in all animals. The fistula created by end-to-end anastomosis remained intact and thus the successful AVM model maintained in all models over a follow-up period as long as more than eight months. The AVM-model in swine could be used as a chronic model to test the neurointerventional techniques of AVM treatment.We re-created the well known AVM-model by a terminal anastomosis between CCA and EJV and we hypothesize that the good long-term patency of the model is related to the type of anastomosis performed between CCA and EJV.

Expression of neurotrophins and their receptors in sciatic nerve of experimentally diabetic rats.

The levels of neurotrophins and their receptor mRNAs were measured in rat sciatic nerve, after 6 or 12 weeks of streptozotocin-induced diabetes. Expression of neurotrophin-3 (NT-3) and neurotrophin-4 (NT-4) was decreased by 50 and 29%, respectively, compared with age-matched controls after 12 weeks of diabetes. Expression of brain-derived neurotrophic factor (BDNF) was not detected. In addition, diabetes induced a reduction in the expression levels of the neurotrophin receptors: trkB mRNA decreased by 50% after 6 weeks of diabetes, but returned to control levels after 12 weeks; meanwhile the trkC and p75LNGFR transcripts were reduced by 20% of control at both times studied. trkA expression was below detection limits. Thus, these data suggest that a reduction in neurotrophin and neurotrophin receptors could contribute to the development and maintenance of diabetic neuropathy.

Effects of alpha-glucosidase inhibition and viscous fibre on diabetic control and postprandial gut hormone responses.

Twelve sulphonylurea-treated Type 2 diabetic patients underwent treatment for 2-week periods with the absorbable alpha-glucosidase inhibitor BAY m1099 (50 mg thrice daily) and with guar granules (5 g thrice daily) separately and together in a sequence-randomized double-blind placebo-controlled study. BAY m1099 and guar reduced the mean fasting plasma glucose from 10.0 +/- 0.7 mmol l-1 to 8.7 +/- 0.5 (p less than 0.05) and 8.3 +/- 0.7 mmol l-1 (p less than 0.01), respectively. Both agents also lowered home-monitored postprandial blood glucose, with BAY m1099 exerting the greater effect. Guar, but not BAY m1099, lowered serum cholesterol from 5.43 +/- 0.52 to 5.29 +/- 0.31 mmol l-1 (p less than 0.05). BAY m1099 reduced the test breakfast plasma responses of glucose (p less than 0.001) and gastric inhibitory polypeptide (GIP, p less than 0.01) and increased those of peptide tyrosine-tyrosine (p less than 0.05) and motilin (p less than 0.01). Guar also reduced plasma glucose concentrations after a test breakfast (p less than 0.05) and increased the response of neurotensin (p less than 0.05). Combining treatments gave no further reduction of postprandial blood glucose concentration and was associated with an increased incidence and severity of gastrointestinal side-effects.

Characterization of a novel prepro VIP derived peptide.

A newly identified, large molecular weight form of peptide histidine methionine (PHM), has been found not only where it was first revealed, in the stomach, but also in high concentrations in the nasal mucosa and urogenital system, though not in the central nervous system, intestine and lung. An antibody to the spacer peptide sequence prepro-VIP 111-122, lying between PHM and VIP, also reacts directly with the large molecular form of PHM. It is suggested that the post-translational processing of prepro-VIP differs between tissues and in some, cleavage may not occur at the C-terminal end of PHM. The biological significance of this is currently unclear.

[Turner's phenotype in a male with deficit of ACTH and gonadotropins (author's transl)]. / Fenotipo Turner en un varón con déficit de gonadotropinas y ACTH.

A case of male Turner's syndrome in a 23-year-old patient is reported. Clinical features included total eunuchoidism, shield-like chest, cubitus valgus, lymphedema in the extremities (hands and feet) and a shortened fourth metacarpal. Hormonal studies revealed very low levels of gonadotropins, cortisol, testosterone and HGH, and normal values for PRL and TSH. Gonadotropin levels did not change after the administration of 100 micrograms LH-RH and 500 micrograms LH-RH every 8 hours during 5 days. Testosterone levels increased when HCG was given. Deficit of ACTH release was demonstrated after the administration of metopyrone, ACTH and 0.1 UI insulin per kilogram of body weight to induce hypoglycemia. Hypoglycemia with insulin and arginine did not determine an increase of GH levels, instead of previous estrogen therapy. These results reveal a hypophyseal hormonal defect in relation to ACTH, LH, FSH and GH release. Hormone abnormalities found in the present case have not been previously described.