Effects of a lycopene-layered double hydroxide composite administration in cells and lungs of adult mice.

Lycopene is a natural compound with one of the highest antioxidant activities. Its consumption is associated with lower risks in lung cancer and chronic obstructive pulmonary disease, for example. Experimentally, a murine model demonstrated the ingestion of lycopene, which reduced the damage in lungs caused by cigarette smoke. Since lycopene is highly hydrophobic, its formulations in supplements and preparations for laboratory assays are based on oils, additionally, bioavailavility is low. We developed a lycopene layered double hydroxide (Lyc-LDH) composite, which is capable of transporting lycopene aqueous media. Our objective was to evaluate the cytotoxicity of Lyc-LDH and the intra-cellular production of reactive oxygen species (ROS) in J774A.1 cells. Also, in vivo assays were conducted with 50 male C57BL/6 mice intranasally treated with Lyc-LDH 10 mg/kg (LG10), Lyc-LDH 25 mg/kg (LG25) and Lyc-LDH 50 mg/kg (LG50) during five days compared against a vehicle (VG) and control (CG) group. The blood, bronchoalveolar lavage fluid (BALF) and lung tissue were analyzed. The results revealed that Lyc-LDH composite attenuated intracellular ROS production stimulated with lipopolysacharide. In BALF, the highest doses of Lyc-LDH (LG25 and LG50) promoted influx of macrophages, lymphocytes, neutrophils and eosinophils compared to CG and VG. Also, LG50 increased the levels of IL-6 and IL-13, and promoted the redox imbalance in the pulmonary tissue. On the contrary, low concentrations did not produce significative effects. In conclusion, our results suggest that intranasal administration of high concentrations of Lyc-LDH induces inflammation as well as redox status changes in the lungs of healthy mice, however, results with low concentrations open a promising way to study LDH composites as vehicles for intranasal administration of antioxidant coadjuvants.

Spherical mesoporous silica designed for the removal of methylene blue from water under strong acidic conditions.

This work proposes a novel technology for environmental remediation based on mesoporous silica spheres, which were successfully synthesized by the solvothermal method using the cetyltrimethylammonium bromide as a structuring agent. The adsorbent was designed to remove cationic dyes at strong acidic conditions. The surface was modified by a careful thermal treatment aiming at the condensation of silanol to siloxane groups. The adsorbent was characterized by XRD, SEM, FTIR, N2 adsorption/desorption and the equilibrium technique to determine the pHpzc. The kinetic of the adsorption followed a pseudo-second-order model and the process was ruled by physical forces. The isotherms were fitted to Freundlich and Temkin models, indicating that the physisorption occurred with multilayer formation, with the interaction adsorbate-adsorbate being relevant to the whole process. The adsorption capacity was approximately 60 mg g-1 and the adsorbents performance in the fast-contact system showed removal of 65%wt. of a 93 mg L-1 methylene blue (MB) solution in a single application.

Electrical properties of polycrystalline GaN films functionalized with cysteine and stabilization of GaN nanoparticles in aqueous media.

GaN was synthesized onto sapphire substrates by chemical vapor deposition, reacting gallium, ammonium chloride and ammonia. The polycrystalline films were immersed in glycine, aspartic acid and cysteine solutions. Cysteine chemisorbed onto GaN films produced detectable changes in conductivity, mobility and Hall coefficient indicating that GaN is capable of detecting and reacting with thiolate groups, which was confirmed by X-ray photoelectron spectroscopy. The Cys-GaN film solution was adjusted to pH 10, upon which the GaN nanoparticles were transferred to the aqueous phase forming a suspension stable for seven days. The alkaline colloid was then further adjusted down to pH 3 retaining stability for three days. The GaN colloid obtained represents a suitable medium to study GaN properties for biological applications.

Intercalation of an oxalatooxoniobate complex into layered double hydroxide and layered zinc hydroxide nitrate.

A Zn/Al layered double hydroxide with molar ratio of 3 was prepared by coprecipitation in alkaline pH and used as a matrix to intercalate the ionic complex diaquadioxalatooxoniobate(V) (DDON), derived from NH(4)[NbO(C(2)O(4))(2)(H(2)O)(2)]2H(2)O. In a similar way, the layered zinc hydroxide nitrate, Zn(5)(OH)(8)(NO(3))(2)2H(2)O, was synthesized, preexpanded with azelate ions ((-)OOC(CH(2))(7)COO(-)), and then intercalated with the niobium complex. For both layered matrices, the results from X-ray powder diffractometry, Fourier transform infrared spectroscopy, and thermal analysis (TG/s-DTA) indicate the presence of the oxalate ion. In addition, results from X-ray photoelectron and Raman spectroscopy indicate the presence of the niobium center bonded to oxygen atoms. Finally, diffuse reflectance UV-vis spectroscopy suggests that the niobium centers are coordinated to oxalate ions. This is the first report of the intercalation of niobium into a layered matrix.

Chemical modification of zinc hydroxide nitrate and Zn-Al-layered double hydroxide with dicarboxylic acids.

A zinc hydroxide nitrate (ZHN), Zn5(OH)8(NO3)2.2H2O, and a layered double hydroxide (LDH), Zn/Al-NO3 were doped with 0.2 mol% of Cu2+ during alkaline chemical precipitation. Both compounds were intercalated with adipate ((-)OOC(CH2)4COO(-)), azelate ((-)OOC(CH2)7COO(-)), and benzoate (C6H5COO(-)) ions through ion exchange reactions. Solid state 13C nuclear magnetic resonance spectroscopy showed only one signal of carboxylic carbon for adipate and azelate intercalated into LDH, indicating that the carboxylic ends of both acids were equivalent, whereas the signal split when the intercalation was into the ZHN matrix. The electron paramagnetic resonance (EPR) spectrum of copper in octahedral cation sites of LDH layers showed a Hamiltonian parameter ratio g ||/A ||=170 cm and, after intercalation of adipate, the change was not significant: g ||/A ||=174 cm. This result indicates that the carboxylate ions did not coordinate with copper centers. Nonetheless, the intercalation of azelate increased the ratio to g ||/A ||=194 cm, similar to the spectra of ZHN modified with adipate, g ||/A ||=199 cm, and azelate, g ||/A ||=183 and 190 cm, which are associated with the coordination of copper by weak carboxylate anion ligands. Copper occupies octahedral or tetrahedral sites in ZHN layers, and the EPR spectra indicate that the dicarboxylate anions reacted preferentially with octahedral sites, whereas benzoate reacted with both sites.

Cu2+ ions as a paramagnetic probe to study the surface chemical modification process of layered double hydroxides and hydroxide salts with nitrate and carboxylate anions.

A layered zinc hydroxide nitrate (Zn5(OH)8(NO3)2.2H2O) and a layered double hydroxide (Zn/Al-NO3) were synthesized by coprecipitation and doped with different amounts of Cu2+ (0.2, 1, and 10 mol%), as paramagnetic probe. Although the literature reports that the nitrate ion is free (with D3h symmetry) between the layers of these two structures, the FTIR spectra of two zinc hydroxide nitrate samples show the C2v symmetry for the nitrate ion, whereas the g ||/A || value in the EPR spectra of Cu2+ is high. This fact suggests bonding of some nitrate ions to the layers of the zinc hydroxide nitrate. The zinc hydroxide nitrate was used as matrix in the intercalation reaction with benzoate, o-chlorobenzoate, and o-iodobenzoate ions. FTIR spectra confirm the ionic exchange reaction and the EPR spectroscopy reveals bonding of the organic ions to the inorganic layers of the zinc hydroxide nitrate, while the layered double hydroxides show only exchange reactions.

Intercalation and functionalization of zinc hydroxide nitrate with mono- and dicarboxylic acids.

The intercalation of ions derived from succinic, glutaric, and adipic acid into layered zinc hydroxide nitrate by ionic exchange reaction is reported. Different reaction conditions are investigated and the materials are characterized by powder X-ray diffraction, Fourier transform infrared spectroscopy, thermal analysis (simultaneous thermogravimetry and differential scanning calorimetry) and elemental analysis. The dicarboxylic acids can be grafted to the matrix slab by one carboxylate group and the second hydrated carboxylate group is hanging between the layers. Benzoate ions have also been intercalated by both ionic exchange reaction and stirring in acetonitrile. The two benzoate-intercalated materials exchange the organic moiety by sulfate ions if stirred in magnesium sulfate solution, but the sample obtained by anion exchange also allows the unusual incorporation of neutral magnesium sulfate in addition to free solvated sulfate ion. A schematic arrangement of the intercalated species between the layers is presented.

First insight into catalytic activity of anionic iron porphyrins immobilized on exfoliated layered double hydroxides.

Mg-Al layered double hydroxide (LDH) intercalated with glycinate anions was synthesized through co-precipitation and exfoliated in formamide and the single-layer suspension was reacted with aqueous iron porphyrin solutions (Fe(TDFSPP) and Fe(TCFSPP)). The obtained materials were characterized by X-ray powder diffraction, UV-vis, and electron paramagnetic resonance and investigated in the oxidation reaction of cyclooctene and cyclohexane using iodosylbenzene as oxidant. The iron porphyrin seems to be immobilized at the surface of the glycinate intercalated LDH. The catalytic activities obtained in heterogeneous media for iron porphyrin, Fe(TDFSPP), was superior to the results obtained under homogeneous conditions, but the opposite effect was observed on the Fe(TCFSPP), indicating that, instead of the structural similarity of both iron porphyrins (second-generation porphyrins), the immobilization of each one produced different catalysts. The best catalytic activity of the Fe(TDFSPP)/Gly-LDH, compared to Fe(TCFSPP)/Gly-LDH, can be explained by the easy access of the oxidant and the substrate to the catalytic sites in the former, probably located at the surface of the layered double hydroxide pillared with glycinate anions. A model for the immobilization and a mechanism for the oxidation reaction will be discussed.