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The use of implants carries on a series of problems, among them infections, poor biocompatibility, high levels of cytotoxicity, and significant mechanical differences between implants and host organs that promote stress shielding effects. These problems indicate that the materials used to make implants must meet essential requirements and high standards for implantations to be successful. In this work, we present the synthesis, characterization and evaluation of the antibiofilm, mechanical, and thermal properties, and cytotoxic effect of a nanocomposite-based scaffold on polyurethane (PU) and gold nanoparticles (AuNPs) for soft tissue applications. The effect of the quantity of AuNPs on the antibacterial activity of nanocomposite scaffolds was evaluated against Staphylococcus epidermidis and Klebsiella spp., with a resulting 99.99% inhibition of both bacteria using a small quantity of nanoparticles. Cytotoxicity was evaluated with the T10 1/2 test against fibroblast cells. The results demonstrated that porous nanogold/PU scaffolds have no toxic effects on fibroblast cells to the 5 day exposition. With respect to mechanical properties, stress-strain curves showed that the compressive modulus and yield strength of PU scaffolds were significantly enhanced by AuNPs (by at least 10 times). This is due to changes in the arrangement of hard segments of PU, which increase the stiffness of the polymer. Thermogravimetric analysis showed that the degradation onset temperature rises with an increase in the quantity of AuNPs. These properties and characteristics demonstrate that porous nanogold/PU scaffolds are suitable material for use in soft tissue implants.

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In the present work, we report on the synthesis of peptide functionalized magneto-plasmonic nanoparticles in a simple microfluidic platform. Superparamagnetic nanoparticles and gold nanorods were selected for this study. Magnetic nanoparticles were functionalized with peptide D1, which can bind selectively to toxic aggregates of the ß-amyloid peptide associated with Alzheimer's disease. Gold nanorods were functionalized with chitosan replacing the surfactant cetyltrimethylammonium bromide to reduce the cytotoxic effect. The selected microfluidic strategy yields structures with plasmonic and magnetic properties in a nanostructure. Cytotoxic assays with SH-SY5Y cells demonstrate that nanoparticles obtained by microfluidics do not affect cell viability at the studied concentrations. Additionally, these magneto-plasmonic nanoparticles inhibit fibril formation demonstrating that the magneto-plasmonic nanoparticles obtained by microfluidics could be applied for a potential treatment and diagnosis of Alzheimer's disease.

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While 2-amino-4-(4-chlorophenyl)thiazole (AT) drug and thiazole derivatives have several biological applications, these compounds present some drawbacks, such as low aqueous solubility and instability. A new complex of ßCD-AT has been synthesized to increase AT solubility and has been used as a substrate for the deposit of solid-state AuNPs via magnetron sputtering, thus forming the ßCD-AT-AuNPs ternary system, which is stable in solution. Complex formation has been confirmed through powder X-ray diffraction and 1D and 2D nuclear magnetic resonance. Importantly, the amine and sulfide groups of AT remained exposed and can interact with the surfaces of the AuNPs. The complex association constant (970 M-1) has been determined using phase solubility analysis. AuNPs formation (32 nm average diameter) has been studied by UV-Visible spectroscopy, transmission/scanning electron microscopy and energy-dispersive X-ray analysis. The in vitro permeability assays show that effective permeability of AT increased using ßCD. In contrast, the ternary system did not have the capacity to diffuse through the membrane. Nevertheless, the antibacterial assays have demonstrated that AT is transferred from ßCD-AT-AuNPs, being available to exert its antibacterial activity. In conclusion, this novel ßCD-AT-AuNPs ternary system is a promising alternative to improve the delivery of AT drugs in therapy.

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Gold nanorods (GNR) use has been proposed in medical applications because of their intrinsic photothermal properties. However, the presence of CTAB molecules adsorbed onto the surface of GNRs results in a highly cytotoxic GNR system. In this work we replace the CTAB molecules with a thiolated chitosan. Once chitosan coated GNRs (Chi-SH-GNR) were attained, a film of alginate (Alg-Chi-SH-GNR) or polyvinyl alcohol (PVA-Chi-SH-GNR) was deposited onto the surface of Chi-GNR by a layer-by-layer process. The photothermal conversion efficiency for the GNR systems was determined irradiating the GNRs suspended in aqua media with a CW 808nm diode laser (CNI, China). The cytotoxicity effect and the photothermal cellular damage of GNR systems were evaluated on a breast cancer cell line. Results show that polymer coats did not affect the transduction photothermal efficiency. Values around 50% were obtained for the different coated gold nanorods. The cytotoxicity of coated gold nanorods diminished significantly compared with those GNR stabilized with CTAB. The laser irradiation of cells treated with gold nanorods showed a decrease in their viability compared with the cells treated but no irradiated.

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In a previous work we demonstrated that toxic aggregates of the protein ß-amyloid (ATAß) involved in the Alzheimer's disease (AD) can be destabilized upon electromagnetic irradiation of the peptide Cys-Leu-Pro-Phe-Phe-Asp (CLPFFD) adsorbed on gold nanospheres (AuNSs). For a selective recognition of the therapeutic target (i.e. ATAß) of AD by the conjugates peptide-nanoparticle it is relevant to understand how the interaction between attached ligands and nanoparticles occurs. In this work a surface enhanced Raman scattering spectroscopy (SERS) study of the interactions of CLPFFD with AuNSs of 10nm average diameter was carried out. The SERS data suggest that phenylalanine displays its aromatic ring coplanar to the surface which is supported by theoretical data obtained from molecular mechanics (MM) and Extended Hückel Theory (EHT) calculations.

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The present study addresses the electrochemical behavior and the analytical applications of six 2-nitrophenylbenzimidazole derivatives with activity against Trypanosoma cruzi. When studied in a wide range of pH, by differential pulse polarography, tast polarography and cyclic voltammetry, these compounds exhibited two irreversible cathodic responses. With analytical purposes, the differential pulse polarography mode was selected, which exhibited adequate analytical parameters of repeatability, reproducibility and selectivity. The percentage of recovery was in all cases over 99%, and the detection and quantitation limits were at the level of 1 x 10(-7)mol L(-1) and 1 x 10(-6)mol L(-1), respectively. In addition, the differential pulse polarography method was successfully applied to study the hydrolytic degradation kinetic of one of the tested compounds. Activation energy, kinetic rate constants at different temperatures and half-life values of such application are reported.

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A field study was performed to evaluate the accuracy of six pesticide screening leaching indexes for herbicide movement. Adsorption, dissipation and soil movement were studied in a vineyard in a sandy loam soil during 2005 season. Simazine, diuron, pendimethalin, oxyfluorfen and flumioxazin were applied to bare soil at rates commonly used, and their soil concentrations throughout soil profile were determined at 0, 10, 20, 40 and 90 days after application (DAA). Herbicides were subjected to two pluviometric regimens, natural field condition and modified conditions (plus natural rainfall 180 mm). Leaching indexes utilized were: Briggs's Rf, Hamaker's Rf, LEACH, LPI, GUS and LIX. Simazine reached 120 cm, diuron 90 cm, flumioxazin 30 cm soil depth respectively. Pendimethalin and oxyfluorfen were retained up to 5 cm. None of the herbicides leaching was affected by rainfall regimen. Only flumioxazin field dissipation was clearly affected by pluviometric condition. The best representation of the herbicide soil depth movement and leaching below 15 cm soil depth were: Hamaker's Rf < Briggs's Rf < GUS < LPI, < LEACH < LIX. Field results showed a good correlation between herbicides K(d) and their soil depth movement and mass leached below 15 cm soil depth.

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The polyamine, cadaverine, was detected in transformed root cultures of Brugmansia candida (syn. Datura candida), a Solanaceae which produces the tropane alkaloids scopolamine and hyoscyamine. To the best of our knowledge, this is the first time that the existence of this uncommon polyamine has been detected in a Datura species. Cadaverine, however, could not be found in the whole plant. The occurrence of cadaverine in hairy roots could be a consequence of either the transformation or a response to stress. Also, cadaverine could be participating in other secondary pathways rather than to the tropane alkaloids. The common polyamines, putrescine, spermidine and spermine were also observed.

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Unlike bilirubin IXalpha (1), the isomers bilirubin IXdelta (2) and neobilirubin IXbeta (3) do not require conjugation with glucuronic acid in order to be excreted. A conformational analysis employing an optimized Monte Carlo method and a mixed Monte Carlo stochastic dynamics reveals that isomer 2 exhibits a structure more closed than the well known 'ridge-tile' conformation of 1. The change in the position of both propionic acid chains causes the loss of at least four hydrogen bonds. On the other hand, the change in the configuration of the distal dipyrrinone and the blockage of the lactamic nitrogen by the presence of a bridge in isomer 3 results in an open and more elongated structure, where the chance of hydrogen bond formation in this region is obliterated. The resulting molecular models for these compounds are consistent with 1H NM R, UV-vis, and TLC data.

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The in vivo metabolism of a bilirubin analog substituted with a propionic acid chain in C8 (5) showed that it is excreted in bile conjugated with glucuronic acid, while a positional isomer substituted with a propionate in C7 (6) is excreted in bile without conjugation. A conformational analysis employing an optimized Monte Carlo method and a mixed Monte Carlo/stochastic dynamics reveals that isomer 5 adopts a 'ridge tile' conformation, stabilized by the presence of three intramolecular hydrogen bonds. On the contrary, isomer 6 exhibits a more closed structure, where impairment in the formation of at least one of the hydrogen bonds occurs. These theoretical predictions agree well with 1H NMR, UV-vis, and TLC data.

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Effects of soybean phytoalexins on the feeding of the soybean looper and Mexican bean beetle were investigated to test the hypothesis that phytoalexins might be a defense mechanism of plants against insects as well as against pathogens. Short-term behavioral responses to the phytoalexins were analyzed using dual-choice tests with phytoalexin-rich and phytoalexin-poor (control) tissues. Phytoalexin production was elicited with ultraviolet radiation. Results from the dual-choice tests indicated that 6th instar soybean looper larvae fed equally on the control and phytoalexin-rich tissues. Feeding by adult and 4th instar Mexican bean beetles, however, was strongly deterred by the phytoalexins as evidenced by "single-bite" mandible scars on the phytoalexin-rich cotyledon discs. Nutritional effects of the isoflavonoid phytoalexin glyceollin on early instar soybean looper larvae were tested by incorporating the phytoalexin into an artificial medium at a level of 1% dry weight (0.15% fresh weight). The larvae were reared for 7 days from emergence on diets of control and glyceollin-containing media. Although survival on the glyceollin diets was initially less than on the control diets, under the experimental conditions glyceollin had no significant effect on the growth, development, or subsequent survival of the larvae. Efficiency of food utilization (ECI) was reduced, indicating that the phytoalexins may be a mild digestibility-reducing factor for the loopers. Implications of the results for host-plant resistance are discussed.