Three-dimensional lanthanide-organic frameworks based on di-, tetra-, and hexameric clusters

Three-dimensional lanthanide-organic frameworks formulated as (CH3)2NH2[Ln(pydc)2] · 1/2H2O [Ln3+ ) Eu3+ (1a) or Er3+ (1b); pydc2- corresponds to the diprotonated residue of 2,5-pyridinedicarboxylic acid (H2pydc)], [Er4(OH)4(pydc)4(H2O)3] ·H2O (2), and [PrIII 2PrIV 1.25O(OH)3(pydc)3] (3) have been isolated from typical solvothermal (1a and 1b in N,N-dimethylformamide - DMF) and hydrothermal (2 and 3) syntheses. Materials were characterized in the solid state using single-crystal X-ray diffraction, thermogravimetric analysis, vibrational spectroscopy (FT-IR and FT-Raman), electron microscopy, and CHN elemental analysis. While synthesis in DMF promotes the formation of centrosymmetric dimeric units, which act as building blocks in the construction of anionic ∞ 3{[Ln(pydc)2]-} frameworks having the channels filled by the charge-balancing (CH3)2NH2 + cations generated in situ by the solvolysis of DMF, the use of water as the solvent medium promotes clustering of the lanthanide centers: structures of 2 and 3 contain instead tetrameric [Er4(μ3-OH)4]8+ and hexameric |Pr6(μ3-O)2(μ3-OH)6| clusters which act as the building blocks of the networks, and are bridged by the H2-xpydcx- residues. It is demonstrated that this modular approach is reflected in the topological nature of the materials inducing 4-, 8-, and 14-connected uninodal networks (the nodes being the centers of gravity of the clusters) with topologies identical to those of diamond (family 1), and framework types bct (for 2) and bcu-x (for 3), respectively. The thermogravimetric studies of compound 3 further reveal a significant weight increase between ambient temperature and 450 °C with this being correlated with the uptake of oxygen from the surrounding environment by the praseodymium oxide inorganic core

Studies of the mechanical properties of lime mortars treated with alkaline earth hydroxide nanoparticles

In the last decades a special attention has been devoted to the development of nanomaterials for conservation and restoration of Cultural heritage. Nanomaterials exhibit distinct properties when compared to their bulk analogues and have been seen as a good alternative of compatible materials for long-term preservation of monuments and artefacts [1-3]. Our studies have been focused on the elaboration and optimization of preparative strategies of micro- and nanolimes and on the study of their efficiency in the consolidation of lime mortars and lime paintings [4, 5]. In this communication we report the synthesis approaches to prepare calcium and magnesium hydroxides nanoparticles, Ca(OH)2 and Mg(OH)2, with chemical precipitation from aqueous solutions. The synthesis is carried out at temperatures range Troom - 90 ºC from equal volumes of NaOH and CaCl2 or MgCl2 solutions with different concentration. We also report our attempt to achieve a good particles morphology by the addition of surfactants. The possibility of the application of their alcohol dispersions in cultural heritage restoration for consolidation of wall paintings on lime mortar renders is anticipated. We discuss the laboratory tests conducted to assess the efficiency of the nanolimes on lime mortar specimens. Furthermore, we report out preliminary studies of the compatibility of the nanoconsolidants with inorganic pigments which have been used in the preparation of the paint layer of wall paintings. [1] Baglioni P., Carretti E., Chelazzi D., Nature Nanotechnology 10, Apr 2015, 287. [2] Borsoi, G., Lunelli, B.; Van Hees, R., Veiga, R., Silva A., Constr. Build. Mater. 142, 2017, 385. [3] Girginova, P.I., Galacho, C., Veiga, R.; Silva, A.S., Candeias, A., ChemSusChem (online). DOI: 10.1002/cssc.201801982 [4] Girginova, P.I., Galacho, C., Mirão, J., Veiga, R., Silva, A.S., Candeias, A., Conservar património 23, 2016, 103. [5] Girginova, P.I., Galacho, C., Veiga, R., Silva, A.S., Candeias, A., submitted.FC

Biofunctionalized ferromagnetic CoPt3/polymer nanocomposites

Magnetic latexes were prepared by the encapsulation of organically capped CoPt3 nanoparticles via miniemulsion in situ radical polymerization of tert-butyl acrylate (tBA). This is the first example of a CoPt3 based polymer nanocomposite showing ferromagnetic behaviour at room temperature. Each nanocomposite particle contains a magnetic core composed of CoPt3 nanoparticles (d ∼ 7 nm, a0 = 3.848 A° ) encapsulated by poly(t-butyl acrylate). The CoPt3/PtBA latexes contain polyester groups that can be readily hydrolysed, rendering the surface with carboxylic functionalities and hence allowing bioconjugation. Complementary to such surface modification experiments, we report that bovine IgG antibodies can bind to the magnetic latexes, and the potential of the nanocomposites for in vitro specific bioapplications is discussed

Lipid peroxidation and its control in Anguilla anguilla hepatocytes under silica-coated iron oxide nanoparticles (with or without mercury) exposure

Having multidisciplinary applications, iron oxide nanoparticles can inevitably enter aquatic system and impact inhabitants such as fish. However, the studies in this context have ignored the significance of obvious interaction of iron oxide nanoparticles with other persistent co-contaminants such as mercury (Hg) in the modulation of the toxicity and underlying mechanisms of iron oxide nanoparticles and Hg alone, and concomitant exposures. This study aimed to evaluate lipid peroxidation (LPO) and its control with glutathione (GSH) and associated enzymes (such as glutathione reductase, GR; glutathione peroxidase, GPX; glutathione sulfo-transferase, GST) in European eel (Anguilla anguilla L.) hepatocytes exposed to stressors with following schemes: (i) no silica-coated iron oxide nanoparticles functionalized with dithiocarbamate (Fe3O4@SiO2/Si DTC, hereafter called 'FeNPs'; size range 82 +/- 21 to 100 +/- 30 nm) or Hg, (ii) FeNPs (2.5 mu g L-1) alone, (iii) Hg (50 mu g L-1) alone and (iv) FeNPs + Hg concomitant condition during 0 to 72 h. The exhibition of a differential coordination between GSH regeneration (determined as GR activity) and GSH metabolism (determined as the activity of GPX and GST) was perceptible in A. anguilla hepatocytes in order to control FeNPs, Hg and FeNPs + Hg exposure condition-mediated LPO. This study revealed the significance of a fine tuning among GR, GPX and GST in keeping LPO level under control during FeNPs or Hg alone exposure, and a direct role of total GSH (TGSH) in the control of LPO level and impaired GSH metabolism under the concomitant (FeNPs + Hg) exposure. An interpretation of the fish risk to FeNPs in a multi-pollution state should equally consider the potential outcome of the interaction of FeNPs with other contaminants

Ferromagnetic Sorbents Based on Nickel Nanowires for Efficient Uptake of Mercury from Water

This work reports the preparation of ferromagnetic nickel nanowires (NiNW) coated with dithiocarbamate-functionalized siliceous shells and its application for the uptake of aqueous Hg(II) ions by magnetic separation. NiNW with an average diameter and length of 35 nm and 5 mu m, respectively, were firstly prepared by Ni electrodeposition in an anodic aluminum oxide template. The NiNW surfaces were then coated with siliceous shells containing dithiocarbamate groups via a one-step procedure consisting in the alkaline hydrolytic co-condensation of tetraethoxysilane (TEOS) and a siloxydithio-carbamate precursor (SiDTC). A small amount of these new nanoadsorbents (2.5 mg.L-1) removed 99.8% of mercury ions from aqueous solutions with concentration 50 mu g.L-1 and in less than 24 h of contact time. This outstanding removal ability is attributed to the high affinity of the sulfur donor ligands to Hg(II) species combined with the high surface area-to-volume ratio of the NiNW

Brain glutathione redox system significance for the control of silica-coated magnetite nanoparticles with or without mercury co-exposures mediated oxidative stress in European eel (Anguilla anguilla L.)

This in vitro study investigates the impact of silicacoated magnetite particles (Fe3O4@SiO2/SiDTC, hereafter called IONP; 2.5 mg L-1) and its interference with coexposure to persistent contaminant (mercury, Hg; 50 mu g L-1) during 0, 2, 4, 8, 16, 24, 48, and 72 h on European eel (Anguilla anguilla) brain and evaluates the significance of the glutathione (GSH) redox system in this context. The extent of damage (membrane lipid peroxidation, measured as thiobarbituric acid reactive substances, TBARS; protein oxidation, measured as reactive carbonyls, RCs) decreased with increasing period of exposure to IONP or IONP + Hg which was accompanied with differential responses of glutathione redox system major components (glutathione reductase, GR; glutathione peroxidase, GPX; total GSH, TGSH). The occurrence of antagonism between IONP and Hg impacts was evident at late hour (72 h), where significantly decreased TBARS and RC levels and GR and glutathione sulfotransferase (GST) activity imply the positive effect of IONP + Hg concomitant exposure against Hg-accrued negative impacts [vs. early (2 h) hour of exposure]. A period of exposuredependent IONP alone and IONP + Hg joint exposureaccrued impact was perceptible. Additionally, increased susceptibility of the GSH redox system to increased period of exposure to Hg was depicted, where insufficiency of elevated GR for the maintenance of TGSH required for membrane lipid and cellular protein protection was displayed. Overall, a finetuning among brain glutathione redox system components was revealed controlling IONP + Hg interactive impacts successfully