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Sample records for double hydroxide ldh

  1. Delamination of layered double hydroxides in polar monomers: new LDH-acrylate nanocomposites.

    PubMed

    O'Leary, Shane; O'Hare, Dermot; Seeley, Gordon

    2002-07-21

    The layered double hydroxide Mg2Al(OH)6(C12H25SO4) was delaminated to give high levels of inclusion in acrylate monomers; subsequent polymerisation of the monomers containing the LDH dispersion gave polyacrylates with the inorganic component still in the delaminated form. PMID:12189866

  2. A pH-responsive layered double hydroxide (LDH)-phthalocyanine nanohybrid for efficient photodynamic therapy.

    PubMed

    Li, Xing-Shu; Ke, Mei-Rong; Huang, Wei; Ye, Chun-Hong; Huang, Jian-Dong

    2015-02-16

    A pH-responsive nanohybrid (LDH-ZnPcPS4 ), in which a highly hydrophilic zinc(II) phthalocyanine tetra-α-substituted with 4-sulfonatophenoxy groups (ZnPcPS4 ) is incorporated with a cationic layered double hydroxide (LDH) based on electrostatic interaction, has been specially designed and prepared through a facile co-precipitation approach. ZnPcPS4 is an excellent singlet-oxygen generator with strong absorption at the near-infrared region (692 nm) in cellular culture media, whereas the photoactivities of ZnPcPS4 were remarkably inhibited after incorporation with the LDH. The nanohybrid is essentially stable in aqueous media at pH 7.4; nevertheless, in slightly acidic media of pH 6.5 or 5.0, ZnPcPS4 can be efficiently released from the LDH matrix, thus leading to restoration of the photoactivities. The nanohybrid shows a high photocytotoxicity against HepG2 cells as a result of much more efficient cellular uptake and preferential accumulation in lysosomes, whereby the acidic environment leads to the release of ZnPcPS4 . The IC50 value of LDH-ZnPcPS4 is as low as 0.053 μM, which is 24-fold lower than that of ZnPcPS4 . This work provides a facile approach for the fabrication of photosensitizers with high photocytotoxicity, potential tumor selectivity, and rapid clearance character. PMID:25639348

  3. Layered double hydroxide/polyethylene terephthalate nanocomposites. Influence of the intercalated LDH anion and the type of polymerization heating method

    SciTech Connect

    Herrero, M.; Martinez-Gallegos, S.; Labajos, F.M.; Rives, V.

    2011-11-15

    Conventional and microwave heating routes have been used to prepare PET-LDH (polyethylene terephthalate-layered double hydroxide) composites with 1-10 wt% LDH by in situ polymerization. To enhance the compatibility between PET and the LDH, terephthalate or dodecyl sulphate had been previously intercalated in the LDH. PXRD and TEM were used to detect the degree of dispersion of the filler and the type of the polymeric composites obtained, and FTIR spectroscopy confirmed that the polymerization process had taken place. The thermal stability of these composites, as studied by thermogravimetric analysis, was enhanced when the microwave heating method was applied. Dodecyl sulphate was more effective than terephthalate to exfoliate the samples, which only occurred for the terephthalate ones under microwave irradiation. - Graphical abstract: Conventional and microwave heating routes were used to prepare PET-LDH (polyethylene terephthalate-layered double hydroxide) composites with 1-10 wt% LDH by in situ polymerization. To enhance the compatibility between PET and the LDH, terephthalate or dodecyl sulphate was previously intercalated into the LDH. The microwave process improves the dispersion and the thermal stability of nanocomposites due to the interaction of the microwave radiation and the dipolar properties of EG and the homogeneous heating. Highlights: > LDH-PET compatibility is enhanced by preintercalation of organic anions. > Dodecylsulphate performance is much better than that of terephthalate. > Microwave heating improves the thermal stability of the composites. > Microwave heating improves as well the dispersion of the inorganic phase.

  4. Insights into the synthesis of layered double hydroxide (LDH) nanoparticles: Part 1. Optimization and controlled synthesis of chloride-intercalated LDH.

    PubMed

    Sun, Xiaodi; Neuperger, Erica; Dey, Sandwip K

    2015-12-01

    Layered double hydroxide (LDH) nanoparticles have excellent anion-intercalating property, and their potential as theranostic nanovectors is high. However, understanding of the control of the mean particle size (MPS) and achievement of monodispersed particle size distribution (PSD) remains elusive. Herein, with the aid of statistical design of experiments on a model system of Cl(-)-intercalated (Zn, Al)-LDH, controlled synthesis of single crystalline nanoparticles using the coprecipitation method followed by hydrothermal treatment (HT) was achieved in three steps. First, a 2(4-1) design enabled the identification of influential parameters for MPS (i.e., salt concentration, molar ratio of carbonate to aluminum, solution addition rate, and interaction between salt concentration and stirring rate) and PSD (i.e., salt concentration and stirring rate), as well as the optimum coprecipitation conditions that result in a monodispersed PSD (i.e., low salt concentration and high stirring rate). Second, a preliminary explanation of the HT was suggested and the optimum HT conditions for obtaining ideal Gaussian PSD with chi-squared (χ(2))<3 were found to be 85°C for 5 h. Third, using a central composite design, a quantitative MPS model, expressed in terms of the significant factors, was developed and experimentally verified to synthesize nearly monodispersed LDH nanoparticles with MPS ∼200-500 nm. PMID:26301838

  5. Highly efficient and selective adsorption of In3+ on pristine Zn/Al layered double hydroxide (Zn/Al-LDH) from aqueous solutions

    NASA Astrophysics Data System (ADS)

    Barnabas, Mary Jenisha; Parambadath, Surendran; Mathew, Aneesh; Park, Sung Soo; Vinu, Ajayan; Ha, Chang-Sik

    2016-01-01

    A pristine Zn/Al-layered double hydroxide (Zn/Al-LDH) showed excellent adsorption ability and selectivity towards In3+ ions from aqueous solutions. The adsorption behaviour as a function of the contact time, solution pH, ionic strength, and amount of adsorbent under ambient conditions revealed a strong dependency on the pH and ionic strength over In3+ intake. The structure and properties of Zn/Al-LDH and In3+ adsorbed Zn/Al-LDH (In-Zn/Al-LDH) were examined carefully by X-ray diffraction, Fourier transform infrared spectroscopy, N2-sorption/desorption, UV-vis spectroscopy, and X-ray photoelectron spectroscopy. The adsorbent had a sufficient number of active sites that were responsible for the In3+ adsorption and quite stable even after the adsorption process. The selective adsorption of In3+ on Zn/Al-LDH was also observed even from a mixture containing competing ions, such as Mn2+, Co2+, Ni2+, Cd2+, Pb2+, and Cu2+. The adsorption experiments showed that Zn/Al-LDH is a promising material for the pre-concentration and selective removal of In3+ from large volumes of aqueous solutions.

  6. Solubility and release of fenbufen intercalated in Mg, Al and Mg, Al, Fe layered double hydroxides (LDH): The effect of Eudragit ® S 100 covering

    NASA Astrophysics Data System (ADS)

    del Arco, M.; Fernández, A.; Martín, C.; Rives, V.

    2010-12-01

    Following different preparation routes, fenbufen has been intercalated in the interlayer space of layered double hydroxides with Mg 2+ and Al 3+ or Mg 2+, Al 3+ and Fe 3+ in the layers. Well crystallized samples were obtained in most of the cases (intercalation was not observed by reconstruction of the MgAlFe matrix), with layer heights ranging between 16.1 and 18.8 Å. The presence of the LDH increases the solubility of fenbufen, especially when used as a matrix. The dissolution rate of the drug decreases when the drug is intercalated, and is even lower in those systems containing iron; release takes place through ionic exchange with phosphate anions from the solution. Preparation of microspheres with Eudragit ® S 100 leads to solids with an homogeneous, smooth surface with efficient covering of the LDH surface, as drug release was not observed at pH lower than 7.

  7. Solubility and release of fenbufen intercalated in Mg, Al and Mg, Al, Fe layered double hydroxides (LDH): The effect of Eudragit S 100 covering

    SciTech Connect

    Arco, M. del; Fernandez, A.; Martin, C.; Rives, V.

    2010-12-15

    Following different preparation routes, fenbufen has been intercalated in the interlayer space of layered double hydroxides with Mg{sup 2+} and Al{sup 3+} or Mg{sup 2+}, Al{sup 3+} and Fe{sup 3+} in the layers. Well crystallized samples were obtained in most of the cases (intercalation was not observed by reconstruction of the MgAlFe matrix), with layer heights ranging between 16.1 and 18.8 A. The presence of the LDH increases the solubility of fenbufen, especially when used as a matrix. The dissolution rate of the drug decreases when the drug is intercalated, and is even lower in those systems containing iron; release takes place through ionic exchange with phosphate anions from the solution. Preparation of microspheres with Eudragit S 100 leads to solids with an homogeneous, smooth surface with efficient covering of the LDH surface, as drug release was not observed at pH lower than 7. - Graphical abstract: LDHs containing Mg, Al, Fe increase fenbufen solubility, release takes place through ionic exchange with phosphate anions from the medium. Spherical solids with homogeneous, smooth surface are formed when using Eudragit S 100, efficiently covering the LDH surface. Display Omitted

  8. Layered double hydroxide stability. 1. Relative stabilities of layered double hydroxides and their simple counterparts

    NASA Technical Reports Server (NTRS)

    Boclair, J. W.; Braterman, P. S.

    1999-01-01

    Solutions containing di- and trivalent metal chlorides [M(II) = Mg2+, Zn2+, Co2+, Ni2+, Mn2+; M(III) = Al3+, Fe3+] were titrated with NaOH to yield hydrotalcite-like layered double hydroxides (LDH), [[M(II)]1-x[M(III)]x(OH)2][Cl]x yH2O, by way of M(III) hydroxide/hydrous oxide intermediates. Analysis of the resultant titration curves yields nominal solubility constants for the LDH. The corresponding LDH stabilities are in the order Mg < Mn < Co approximately Ni < Zn for M(II) and Al < Fe for M(III). The stability of LDH relative to the separate metal hydroxides/hydrous oxides is discussed.

  9. Methotrexate intercalated ZnAl-layered double hydroxide

    SciTech Connect

    Chakraborty, Manjusha; Dasgupta, Sudip; Soundrapandian, Chidambaram; Chakraborty, Jui; Ghosh, Swapankumar; Mitra, Manoj K.; Basu, Debabrata

    2011-09-15

    The anticancerous drug methotrexate (MTX) has been intercalated into an ZnAl-layered double hydroxide (LDH) using an anion exchange technique to produce LDH-MTX hybrids having particle sizes in the range of 100-300 nm. X-ray diffraction studies revealed increases in the basal spacings of ZnAl-LDH-MTX hybrid on MTX intercalation. This was corroborated by the transmission electron micrographs, which showed an increase in average interlayer spacing from 8.9 A in pristine LDH to 21.3 A in LDH-MTX hybrid. Thermogravimetric analyses showed an increase in the decomposition temperature for the MTX molecule in the LDH-MTX hybrid indicating enhanced thermal stability of the drug molecule in the LDH nanovehicle. The cumulative release profile of MTX from ZnAl-LDH-MTX hybrids in phosphate buffer saline (PBS) at pH 7.4 was successfully sustained for 48 h following Rigter-Peppas model release kinetics via diffusion. - Graphical abstract: ZnAl-layered double hydroxide intercalated with methotrexate ({approx}34% loading) promises the possibility of use of ZnAl-LDH material as drug carrier and in controlled delivery. Highlights: > ZnAl-layered double hydroxide methotrexate nanohybrid has been synthesized. > XRD and TEM studies on nanohybrid revealed successful intercalation of methotrexate. > TG and CHN analyses showed {approx}34 wt% of methotrexate loading into the nanohybrid. > Possibility of use of ZnAl-LDH material as drug carrier and in delivery.

  10. Biological evaluation of layered double hydroxides as efficient drug vehicles.

    PubMed

    Li, Yan; Liu, Dan; Ai, Hanhua; Chang, Qing; Liu, Dandan; Xia, Ying; Liu, Shuwen; Peng, Nanfang; Xi, Zhuge; Yang, Xu

    2010-03-12

    Recently there has been a rapid expansion of the development of bioinorganic hybrid systems for safe drug delivery. Layered double hydroxides (LDH), a variety of available inorganic matrix, possess great promise for this purpose. In this study, an oxidative stress biomarker system, including measurement of reactive oxygen species, glutathione content, endogenous nitric oxide, carbonyl content in proteins, DNA strand breaks and DNA-protein crosslinks, was designed to evaluate the biocompatibility of different concentrations of nano-Zn/Al-LDH with a Hela cell line. The drug delivery activity of the LDH-folic-acid complex was also assessed. The resulting data clearly demonstrated that nano-LDH could be applied as a relatively safe drug vehicle with good delivery activity, but with the caveat that the effects of high dosages observed here should not be ignored when attempting to maximize therapeutic activity by increasing LDH concentration. PMID:20154371

  11. Synthesis of layered double hydroxide nanosheets by coprecipitation using a T-type microchannel reactor

    SciTech Connect

    Pang, Xiujiang; Sun, Meiyu; Ma, Xiuming; Hou, Wanguo

    2014-02-15

    The synthesis of Mg{sub 2}Al–NO{sub 3} layered double hydroxide (LDH) nanosheets by coprecipitation using a T-type microchannel reactor is reported. Aqueous LDH nanosheet dispersions were obtained. The LDH nanosheets were characterized by X-ray diffraction, transmission electron microscopy, atomic force microscopy and particle size analysis, and the transmittance and viscosity of LDH nanosheet dispersions were examined. The two-dimensional LDH nanosheets consisted of 1–2 brucite-like layers and were stable for ca. 16 h at room temperature. In addition, the co-assembly between LDH nanosheets and dodecyl sulfate (DS) anions was carried out, and a DS intercalated LDH nanohybrid was obtained. To the best of our knowledge, this is the first report of LDH nanosheets being directly prepared in bulk aqueous solution. This simple, cheap method can provide naked LDH nanosheets in high quantities, which can be used as building blocks for functional materials. - Graphical abstract: Layered double hydroxide (LDH) nanosheets were synthesized by coprecipitation using a T-type microchannel reactor, and could be used as basic building blocks for LDH-based functional materials. Display Omitted - Highlights: • LDH nanosheets were synthesized by coprecipitation using a T-type microchannel reactor. • Naked LDH nanosheets were dispersed in aqueous media. • LDH nanosheets can be used as building blocks for functional materials.

  12. Subcellular compartment targeting of layered double hydroxide nanoparticles.

    PubMed

    Xu, Zhi Ping; Niebert, Marcus; Porazik, Katharina; Walker, Tara L; Cooper, Helen M; Middelberg, Anton P J; Gray, Peter P; Bartlett, Perry F; Lu, Gao Qing Max

    2008-08-25

    Current investigations show that layered double hydroxide (LDH) nanoparticles have high potential as effective non-viral agents for cellular drug delivery due to their low cytotoxicity, good biocompatibility, high drug loading, control of particle size and shape, targeted delivery and drug release control. Two types of Mg(2)Al-LDH nanoparticles with fluorescein isothiocyanate (FITC) were controllably prepared. One is morphologically featured as typical hexagonal sheets (50-150 nm laterally wide and 10-20 nm thick), while the other as typical rods (30-60 nm wide and 100-200 nm long). These LDH(FTIC) nanoparticles are observed to immediately transfect into different mammalian cell lines. We found that internalized LDH(FITC) nanorods are quickly translocated into the nucleus while internalized LDH(FITC) nanosheets are retained in the cytoplasm. Inhibition experiments show that the cellular uptake is a clathrin-mediated time- and concentration-dependent endocytosis. Endosomal escape of LDH(FITC) nanoparticles is suggested to occur through the deacidification of LDH nanoparticles. Since quick nuclear targeting of LDH(FITC) nanorods requires an active process, and although the exact mechanism is yet to be fully understood, it probably involves an active transport via microtubule-mediated trafficking processes. Targeted addressing of two major subcellular compartments by simply controlling the particle morphology/size could find a number of applications in cellular biomedicine. PMID:18614254

  13. Methotrexate intercalated ZnAl-layered double hydroxide

    NASA Astrophysics Data System (ADS)

    Chakraborty, Manjusha; Dasgupta, Sudip; Soundrapandian, Chidambaram; Chakraborty, Jui; Ghosh, Swapankumar; Mitra, Manoj K.; Basu, Debabrata

    2011-09-01

    The anticancerous drug methotrexate (MTX) has been intercalated into an ZnAl-layered double hydroxide (LDH) using an anion exchange technique to produce LDH-MTX hybrids having particle sizes in the range of 100-300 nm. X-ray diffraction studies revealed increases in the basal spacings of ZnAl-LDH-MTX hybrid on MTX intercalation. This was corroborated by the transmission electron micrographs, which showed an increase in average interlayer spacing from 8.9 Å in pristine LDH to 21.3 Å in LDH-MTX hybrid. Thermogravimetric analyses showed an increase in the decomposition temperature for the MTX molecule in the LDH-MTX hybrid indicating enhanced thermal stability of the drug molecule in the LDH nanovehicle. The cumulative release profile of MTX from ZnAl-LDH-MTX hybrids in phosphate buffer saline (PBS) at pH 7.4 was successfully sustained for 48 h following Rigter-Peppas model release kinetics via diffusion.

  14. Tunable Electronic Transport Properties of 2D Layered Double Hydroxide Crystalline Microsheets with Varied Chemical Compositions.

    PubMed

    Zhao, Yibing; Hu, Hai; Yang, Xiaoxia; Yan, Dongpeng; Dai, Qing

    2016-09-01

    Transistors based on layered double hydroxides (LDH) single microcrystal are fabricated, whose conductivity of LDH can be tuned by varying metal cations or interlayer anions, but weakly affected by external electric field. The carrier mobility can reach about 1 × 10(-5) cm(2) V(-1) s(-1) , a value comparable to that of organic C60-based transistors. This work paves a way for future electrical applications of LDH. PMID:27416544

  15. New antimony substituted Mg-Al layered double hydroxides.

    PubMed

    Kim, Jin A; Hwang, Seong-Ju; Choy, Jin-Ho

    2008-10-01

    No antimony hydroxide has been previously reported not only in solid state but also in aqueous solution, surely due to the fact that the formation of antimony oxide, Sb2O3, is thermodynamically more favorable than that of the hydroxide phase, Sb(OH)3. According to the pH dependent solubility diagram of Sb2O3, antimony (III) hydroxide may not exist as a definite compound but be proposed as a hydrated monomeric molecular species, Sb(OH)3(aq), which is in equilibrium with Sb2O3, under a condition of very small ionic strength. This is probably the reason why no Sb(3+)-containing layered double hydroxide, LDH, has been reported as yet. In the present study, an attempt has been made to prepare new Sb(3+)-LDH by substituting the Al3+ in octahedral site partially with Sb3+ up to approximately 10%. From the X-ray diffraction analysis, we found that the lattice constants (a = 3.075 angstroms, c = 23.788 angstroms) of the pristine, Mg-Al LDH, increased gradually upto those (a = 3.087 angstroms, c = 24.167 angstroms) of Sb-LDH (8%-substituted). Beyond 10%, the Sb substitution does not lead to any further increases of lattice constants but the impurity Sb2O3 phase is formed. It is, therefore, concluded that the solubility limit of Sb3+ in LDH would be around 10%. In addition, we were able to determine the chemical formula of Sb-substituted LDHs as follows, Mg4Al(1-x)Sb(x)OH10(CO3)(1/2) x H2O (x = 0 approximately 0.08) on the basis of energy dispersive X-ray spectroscopy. PMID:19198414

  16. Facile synthesis of deoxycholate intercalated layered double hydroxide nanohybrids via a coassembly process

    SciTech Connect

    Wu, Xiaowen; Wang, Shuang; Du, Na; Zhang, Renjie; Hou, Wanguo

    2013-07-15

    In this paper, we describe a synthesis strategy of deoxycholate (DC) intercalated layered double hydroxide (LDH) nanohybrids via a coassembly method at room temperature. For this strategy, LDH particles were delaminated to well-dispersed 2D nanosheets in formamide, and the resulting LDH nanosheets were then coassembled with DC anions into the DC intercalated LDH (DC-LDH) nanohybrids. The so-synthesized nanohybrids were characterized by XRD, TEM, FT-IR, elemental analyses and TG-DSC. It was found that the loading amount of DC in the nanohybrids could be easily controlled by changing the ratio of DC to LDH. In addition, the nanohybrids have similar characteristics with the DC-LDH nanohybrids synthesized by the hydrothermal method, including their DC loading, crystal structure, morphology and thermal gravimetric behavior. However, this strategy exhibited the advantages of short reaction time and mild experimental conditions compared with the hydrothermal method. - Graphical abstract: Deoxycholate intercalated layered double hydroxide nanohybrids were successfully synthesized via a coassembly strategy. In this strategy, the interlayer spaces of LDHs can be efficiently used for the intercalation of guest species. - Highlights: • Deoxycholate intercalated layered double hydroxide nanohybrids were synthesized via a coassembly strategy. • This strategy exhibited the advantages of short time and mild conditions. • This strategy can enable organic species to be readily intercalated into the LDH galleries.

  17. Magnetic alginate-layered double hydroxide composites for phosphate removal.

    PubMed

    Lee, Chang-Gu; Kim, Song-Bae

    2013-01-01

    The objective of this study was to investigate phosphate removal using magnetic alginate-layered double hydroxide (LDH) composites. The magnetic composites were prepared by entrapping synthetic magnetic iron oxide and calcined Mg-Al LDH in polymer matrix (alginate). Results showed that the magnetic composites (2% magnetic iron oxide and 6% calcined Mg-Al LDH) were effective in the removal of phosphate with the sorption capacity of 5.0 +/- 0.1 mgP/g under given experimental conditions (adsorbent dose = 0.05 g in 30 ml solution; initial phosphate concentration = 10 mgP/l; reaction time = 24 h). Both magnetic iron oxide and calcined Mg-Al LDH have the ability to adsorb phosphate, with the latter having much higher sorption capacity. In the magnetic composites, calcined Mg-Al LDH functions as a phosphate adsorbent while magnetic iron oxide provides both magnetic and sorption properties. Results also demonstrated that phosphate sorption to the magnetic composites reached equilibrium at 24 h. The maximum phosphate sorption capacity was determined to be 39.1 mgP/g. In addition, phosphate removal was not sensitive to initial solution pH between 4.1 and 10.2. Only 9% of the phosphate sorption capacity was reduced as the solution pH increased from 4.1 to 10.2. This study demonstrated that magnetic alginate-LDH composites could be used for phosphate removal in combination with magnetic separation. PMID:24527638

  18. Sugar-anionic clay composite materials: intercalation of pentoses in layered double hydroxide

    NASA Astrophysics Data System (ADS)

    Aisawa, Sumio; Hirahara, Hidetoshi; Ishiyama, Kayoko; Ogasawara, Wataru; Umetsu, Yoshio; Narita, Eiichi

    2003-09-01

    The intercalation of non-ionized guest pentoses (ribose and 2-deoxyribose) into the Mg-Al and Zn-Al layered double hydroxides (LDHs) was carried out at 298 K by the calcination-rehydration reaction using the Mg-Al and Zn-Al oxide precursors calcined at 773 K. The resulting solid products reconstructed the LDH structure with incorporating pentoses, and the maximum amount of ribose intercalated by the Mg-Al oxide precursor was approximately 20 times that by the Zn-Al oxide precursor. The ribose/Mg-Al LDH was observed to have the expanded LDH structure with a broad (003) spacing of 0.85 nm. As the thickness of the LDH hydroxide basal layer is 0.48 nm, the interlayer distance of the ribose/Mg-Al LDH is 0.37 nm. This value corresponds to molecular size of ribose in thickness (0.36 nm), supporting that ribose is horizontally oriented in the interlayer space of LDH. The maximum amount of ribose intercalated by the Mg-Al oxide precursor was approximately 5 times that of 2-deoxyribose. Ribose is substituted only by the hydroxyl group at C-2 position for 2-deoxyribose. Therefore, the number of hydroxyl group of sugar is essentially important for the intercalation of sugar molecule into the LDH, suggesting that the intercalation behavior of sugar for the LDH was greatly influenced by hydrogen bond between hydroxyl group of the intercalated pentose and the LDH hydroxide basal layers.

  19. Polymer Coated CaAl-Layered Double Hydroxide Nanomaterials for Potential Calcium Supplement

    PubMed Central

    Kim, Tae-Hyun; Lee, Jeong-A; Choi, Soo-Jin; Oh, Jae-Min

    2014-01-01

    We have successfully prepared layered double hydroxide (LDH) nanomaterials containing calcium and aluminum ions in the framework (CaAl-LDH). The surface of CaAl-LDH was coated with enteric polymer, Eudragit®L 100 in order to protect nanomaterials from fast dissolution under gastric condition of pH 1.2. The X-ray diffraction patterns, Fourier transform infrared spectroscopy, scanning electron and transmission electron microscopy revealed that the pristine LDH was well prepared having hydrocalumite structure, and that the polymer effectively coated the surface of LDH without disturbing structure. From thermal analysis, it was determined that only a small amount (less than 1%) of polymer was coated on the LDH surface. Metal dissolution from LDH nanomaterials was significantly reduced upon Eudragit®L 100 coating at pH 1.2, 6.8 and 7.4, which simulates gastric, enteric and plasma conditions, respectively, and the dissolution effect was the most suppressed at pH 1.2. The LDH nanomaterials did not exhibit any significant cytotoxicity up to 1000 μg/mL and intracellular calcium concentration significantly increased in LDH-treated human intestinal cells. Pharmacokinetic study demonstrated absorption efficiency of Eudragit®L 100 coated LDH following oral administration to rats. Moreover, the LDH nanomaterials did not cause acute toxic effect in vivo. All the results suggest the great potential of CaAl-LDH nanomaterials as a calcium supplement. PMID:25490138

  20. Double-Shelled Nanocages with Cobalt Hydroxide Inner Shell and Layered Double Hydroxides Outer Shell as High-Efficiency Polysulfide Mediator for Lithium-Sulfur Batteries.

    PubMed

    Zhang, Jintao; Hu, Han; Li, Zhen; Lou, Xiong Wen David

    2016-03-14

    Lithium-sulfur (Li-S) batteries have been considered as a promising candidate for next-generation electrochemical energy-storage technologies because of their overwhelming advantages in energy density. Suppression of the polysulfide dissolution while maintaining a high sulfur utilization is the main challenge for Li-S batteries. Here, we have designed and synthesized double-shelled nanocages with two shells of cobalt hydroxide and layered double hydroxides (CH@LDH) as a conceptually new sulfur host for Li-S batteries. Specifically, the hollow CH@LDH polyhedra with complex shell structures not only maximize the advantages of hollow nanostructures for encapsulating a high content of sulfur (75 wt %), but also provide sufficient self-functionalized surfaces for chemically bonding with polysulfides to suppress their outward dissolution. When evaluated as cathode material for Li-S batteries, the CH@LDH/S composite shows a significantly improved electrochemical performance. PMID:26894940

  1. Preparation of the poly(vinyl alcohol)/layered double hydroxide nanocomposite

    SciTech Connect

    Li Baoguang; Hu Yuan; Zhang Rui; Chen Zuyao; Fan Weicheng

    2003-10-01

    Intercalated nanocomposite based on Mg, Al layered double hydroxide (LDH) and poly(vinyl alcohol) (PVA) was prepared using exfoliation-adsorption technique, and characterized by X-ray diffraction and thermal gravimetric analysis. The results suggest that the intercalated species are formed via the re-aggregation of the delaminated LDH lamellar with the interlayer spacing 14.5 A, and the thermal stability of the nanocomposite improved compared with the original PVA.

  2. Functionalized layered double hydroxide nanoparticles conjugated with disulfide-linked polycation brushes for advanced gene delivery.

    PubMed

    Hu, H; Xiu, K M; Xu, S L; Yang, W T; Xu, F J

    2013-06-19

    Layered double hydroxides (LDHs) have aroused great attention as potential nanosized drug delivery carriers, but independent inorganic LDH wrapped with DNA shows very low transfection efficiency. To manipulate and control the surface properties of LDH nanoparticles is of crucial importance in the designing of LDH-based drug carriers. In this work, surface-initiated atom transfer radical polymerization (ATRP) of 2-(dimethylamino)ethyl methacrylate (DMAEMA) is employed to tailor the functionality of LDH surfaces in a well-controlled manner and produce a series of well-defined novel gene delivery vectors (termed as LDH-PDs), where a flexible three-step method was first developed to introduce the ATRP initiation sites containing disulfide bonds onto LDH surfaces. In comparison the pristine LDH particles, the resultant LDH-PDs exhibited better ability to condense plasmid DNA (pDNA) and much higher levels to delivery genes in different cell lines including COS7 and HepG2 cell lines. Moreover, the LDH-PDs also could largely enhance cellular uptake. This present study demonstrates that functionalization of bioinorganic LDH with flexible polycation brushes is an effective means to produce new LDH-based gene delivery systems. PMID:23682934

  3. One-step direct synthesis of layered double hydroxide single-layer nanosheets

    NASA Astrophysics Data System (ADS)

    Yu, Jingfang; Martin, Benjamin R.; Clearfield, Abraham; Luo, Zhiping; Sun, Luyi

    2015-05-01

    Layered double hydroxide (LDH) single-layer nanosheets were traditionally prepared through a multi-step exfoliation process which is very time-consuming and of low efficiency. Herein we report the preparation of LDH single-layer nanosheets through a facile direct synthesis method. By introducing a layer growth inhibitor, one can directly synthesize LDH single-layer nanosheets instead of LDH layered compounds. The inhibitor weakens the interactions between neighboring layers, thus preventing the interlayer growth. This investigation on blocking interlayer growth by weakening interlayer interactions to obtain inorganic single-layer nanosheets opens a new route for the synthesis of 2-dimensional materials.Layered double hydroxide (LDH) single-layer nanosheets were traditionally prepared through a multi-step exfoliation process which is very time-consuming and of low efficiency. Herein we report the preparation of LDH single-layer nanosheets through a facile direct synthesis method. By introducing a layer growth inhibitor, one can directly synthesize LDH single-layer nanosheets instead of LDH layered compounds. The inhibitor weakens the interactions between neighboring layers, thus preventing the interlayer growth. This investigation on blocking interlayer growth by weakening interlayer interactions to obtain inorganic single-layer nanosheets opens a new route for the synthesis of 2-dimensional materials. Electronic supplementary information (ESI) available: Synthesis methods and SEM, EDX, XRD and scheme. See DOI: 10.1039/c5nr01077b

  4. Intercalation of Anionic Oxalato Complexes into Layered Double Hydroxides

    NASA Astrophysics Data System (ADS)

    Prevot, V.; Forano, C.; Besse, J. P.

    2000-09-01

    Intercalation compounds of layered double hydroxide (LDH), MII1-xMIIIx(OH)2Ax/y·nH2O (with MII=Zn, Cu and MIII=Al, Cr, Ga), with oxalato complexes of aluminium, gallium, chromium, copper, and beryllium, were obtained via anion-exchange processes. Powder X-ray diffraction indicated that the intercalation reactions were successful. The basal spacings measured after intercalation are near 0.98±0.02 nm, whatever the host matrix composition. Studies by FTIR spectroscopy confirmed the intercalation of the oxalato complex, too. In order to study the thermal decomposition of the exchanged products, TGA-coupled mass spectrometry was performed.

  5. Layered Double Hydroxide-Based Nanocarriers for Drug Delivery

    PubMed Central

    Bi, Xue; Zhang, Hui; Dou, Liguang

    2014-01-01

    Biocompatible clay materials have attracted particular attention as the efficient drug delivery systems (DDS). In this article, we review developments in the use of layered double hydroxides (LDHs) for controlled drug release and delivery. We show how advances in the ability to synthesize intercalated structures have a significant influence on the development of new applications of these materials. We also show how modification and/or functionalization can lead to new biotechnological and biomedical applications. This review highlights the most recent progresses in research on LDH-based controlled drug delivery systems, focusing mainly on: (i) DDS with cardiovascular drugs as guests; (ii) DDS with anti-inflammatory drugs as guests; and (iii) DDS with anti-cancer drugs as guests. Finally, future prospects for LDH-based drug carriers are also discussed. PMID:24940733

  6. Biopolymer immobilization during the crystalline growth of layered double hydroxide

    NASA Astrophysics Data System (ADS)

    Leroux, Fabrice; Gachon, Julien; Besse, Jean-Pierre

    2004-01-01

    Alginic acid, a biopolymer produced by brown seaweed, is incorporated between the sheets of a layered double hydroxide (LDH) via direct coprecipitation. The growth of the inorganic crystalline seeds over the polymer gives rise to a lamellar structure. The obtained nanocomposite presents a basal spacing in agreement with the ideal picture of the polymer lying perpendicularly to the inorganic sheets. A study using FTIR and 13C CP-MAS spectroscopies suggests that the interaction between the organic guest and the inorganic framework is weak. However, the polymer has a stabilizing effect in temperature, since ZnO is observed at 350°C, whereas it appears at 200°C for the chloride LDH pristine material.

  7. Structural characterisation of a layered double hydroxide nanosheet

    NASA Astrophysics Data System (ADS)

    Funnell, Nicholas P.; Wang, Qiang; Connor, Leigh; Tucker, Matthew G.; O'Hare, Dermot; Goodwin, Andrew L.

    2014-06-01

    We report the atomic-scale structure of a Zn2Al-borate layered double hydroxide (LDH) nanosheet, as determined by reverse Monte Carlo (RMC) modelling of X-ray total scattering data. This study involves the extension of the RMC method to enable structural refinement of two-dimensional nanomaterials. The refined LDH models show the intra-layer geometry in this highly-exfoliated phase to be consistent with that observed in crystalline analogues, with the reciprocal-space scattering data suggesting a disordered arrangement of the Zn2+ and Al3+ cations within the nanosheet. The approach we develop is generalisable and so offers a method of characterising the structures of arbitrary nanosheet phases, including systems that support complex forms of disorder within the nanosheets themselves.We report the atomic-scale structure of a Zn2Al-borate layered double hydroxide (LDH) nanosheet, as determined by reverse Monte Carlo (RMC) modelling of X-ray total scattering data. This study involves the extension of the RMC method to enable structural refinement of two-dimensional nanomaterials. The refined LDH models show the intra-layer geometry in this highly-exfoliated phase to be consistent with that observed in crystalline analogues, with the reciprocal-space scattering data suggesting a disordered arrangement of the Zn2+ and Al3+ cations within the nanosheet. The approach we develop is generalisable and so offers a method of characterising the structures of arbitrary nanosheet phases, including systems that support complex forms of disorder within the nanosheets themselves. Electronic supplementary information (ESI) available. See DOI: 10.1039/c4nr01265h

  8. Treatment with coated layer double hydroxide clays decreases the toxicity of copper-contaminated water.

    PubMed

    Blake, Deanne; Nar, Mangesh; D'Souza, Nandika Anne; Glenn, J Brad; Klaine, Stephen J; Roberts, Aaron P

    2014-05-01

    Copper is a common pollutant found in watersheds that exerts toxic effects on both invertebrates and vertebrates. Layer double hydroxide (LDH) clays are able to adsorb a wide range of contaminants through ion-exchange mechanisms. Coating LDH clays with various materials alters the aggregation of clay particles into the nano-size range, thus increasing relative surface area and offering great potential for contaminant remediation. The goal of this study was to determine if treatment with coated LDH clays decreases the toxicity of copper-containing solutions to Daphnia magna. Four LDH clays with different coatings used to alter hydrophobicity were as follows: used: Na(+) montmorillonite, Zn-Al LDH-nitrate, Zn-Al LDH-stearate, and Zn-Al LDH-carbonate. It was determined that coated LDH clays decreased copper toxicity by decreasing bioavailability and that smaller aggregate sizes decreased bioavailability the most. 96 h LC50 values increased by as much as 4.2 times with the treatment of the solutions with 100 mg/L LDH clay. Copper analysis of the clay and solutions indicated that the clays work by decreasing copper bioavailability by way of a binding mechanism. Coated LDH clays hold promise as a small-scale remediation tool or as an innovative tool for toxicity identification and evaluation characterization of metals. PMID:24442186

  9. High-Density Protein Loading on Hierarchically Porous Layered Double Hydroxide Composites with a Rational Mesostructure.

    PubMed

    Tokudome, Yasuaki; Fukui, Megu; Tarutani, Naoki; Nishimura, Sari; Prevot, Vanessa; Forano, Claude; Poologasundarampillai, Gowsihan; Lee, Peter D; Takahashi, Masahide

    2016-09-01

    Hierarchically porous biocompatible Mg-Al-Cl-type layered double hydroxide (LDH) composites containing aluminum hydroxide (Alhy) have been prepared using a phase-separation process. The sol-gel synthesis allows for the hierarchical pores of the LDH-Alhy composites to be tuned, leading to a high specific solid surface area per unit volume available for high-molecular-weight protein adsorptions. A linear relationship between the effective surface area, SEFF, and loading capacity of a model protein, bovine serum albumin (BSA), is established following successful control of the structure of the LDH-Alhy composite. The threshold of the mean pore diameter, Dpm, above which BSA is effectively adsorbed on the surface of LDH-Alhy composites, is deduced as 20 nm. In particular, LDH-Alhy composite aerogels obtained via supercritical drying exhibit an extremely high capacity for protein loading (996 mg/g) as a result of a large mean mesopore diameter (>30 nm). The protein loading on LDH-Alhy is >14 times that of a reference LDH material (70 mg/g) prepared via a standard procedure. Importantly, BSA molecules pre-adsorbed on porous composites were successfully released on soaking in ionic solutions (HPO4(2-) and Cl(-) aqueous). The superior capability of the biocompatible LDH materials for loading, encapsulation, and releasing large quantities of proteins was clearly demonstrated. PMID:27501777

  10. Ternary NiFeMn layered double hydroxides as highly-efficient oxygen evolution catalysts.

    PubMed

    Lu, Zhiyi; Qian, Li; Tian, Yang; Li, Yaping; Sun, Xiaoming; Duan, Xue

    2016-01-18

    Layered double hydroxides (LDHs) are a family of layer materials that receive heightened attention. Herein a ternary NiFeMn-LDH is investigated with superior oxygen evolution activity, which is attributed to the Mn(4+) doping in the intralayer, which modifies the electronic structure and improves the conductivity of the electrocatalyst. PMID:26579843

  11. Efficient drug delivery using SiO2-layered double hydroxide nanocomposites.

    PubMed

    Li, Li; Gu, Zi; Gu, Wenyi; Liu, Jian; Xu, Zhi Ping

    2016-05-15

    MgAl-layered double hydroxide (MgAl-LDH) nanoparticles have great potentials in drug and siRNA delivery. In this work, we used a nanodot-coating strategy to prepare SiO2 dot-coated layered double hydroxide (SiO2@MgAl-LDH) nanocomposites with good dispersibility and controllable size for drug delivery. The optimal SiO2@MgAl-LDH nanocomposite was obtained by adjusting synthetic parameters including the mass ratio of MgAl-LDH to SiO2, the mixing temperature and time. The optimal SiO2@MgAl-LDH nanocomposite was shown to have SiO2 nanodots (10-15nm in diameter) evenly deposited on the surface of MgAl-LDHs (110nm in diameter) with the plate-like morphology and the average hydrodynamic diameter of 170nm. We further employed SiO2@MgAl-LDH nanocomposite as a nanocarrier to deliver methotrexate (MTX), a chemotherapy drug, to the human osteosarcoma cell (U2OS) and found that MTX delivered by SiO2@MgAl-LDH nanocomposite apparently inhibited the U2OS cell growth. PMID:26930539

  12. APPLICATIONS OF LAYERED DOUBLE HYDROXIDES IN REMOVING OXYANIONS FROM OIL REFINING AND COAL MINING WASTEWATER

    SciTech Connect

    Song Jin; Paul Fallgren

    2006-03-01

    Western Research Institute (WRI), in conjunction with the U.S. Department of Energy (DOE), conducted a study of using the layered double hydroxides (LDH) as filter material to remove microorganisms, large biological molecules, certain anions and toxic oxyanions from various waste streams, including wastewater from refineries. Results demonstrate that LDH has a high adsorbing capability to those compounds with negative surface charge. Constituents studied include model bacteria, viruses, arsenic, selenium, vanadium, diesel range hydrocarbons, methyl tert-butyl ether (MTBE), mixed petroleum constituents, humic materials and anions. This project also attempted to modify the physical structure of LDH for the application as a filtration material. Flow characterizations of the modified LDH materials were also investigated. Results to date indicate that LDH is a cost-effective new material to be used for wastewater treatment, especially for the treatment of anions and oxyanions.

  13. A novel nanocomposite material prepared by intercalating photoresponsive dendrimers into a layered double hydroxide

    SciTech Connect

    Tanaka, Toshiyuki; Nishimoto, Shunsuke; Kameshima, Yoshikazu; Matsukawa, Junpei; Fujita, Yasuhiko; Takaguchi, Yutaka; Matsuda, Motohide; Miyake, Michihiro

    2010-02-15

    A novel combination for an inorganic-organic nanocomposite material was demonstrated. Anthryl dendron, i.e., poly(amidoamine) dendron with an anthracene chromophore group at the focal point, was incorporated in the interlayer space of ZnAl-NO{sub 3} type layered double hydroxide (LDH) through an anion-exchange reaction. The photoabsorption and fluorescence properties of the resulting material were different from those of the bare anthryl dendron molecule. It was suggested that the change in photochemical properties was due to the organization and pi-pi interaction of anthracene chromophores within the interlayer of the LDH. - Graphical abstract: A novel inorganic-organic nanocomposite material, a layered double hydroxide (LDH) containing photoresponsive dendrimers in the interlayer space, was successfully prepared through an ion-exchange reaction. The resulting material exhibited unique photochemical properties, compared to those of the bare photoresponsive dendrimer molecule.

  14. Efficient uranium capture by polysulfide/layered double hydroxide composites.

    PubMed

    Ma, Shulan; Huang, Lu; Ma, Lijiao; Shim, Yurina; Islam, Saiful M; Wang, Pengli; Zhao, Li-Dong; Wang, Shichao; Sun, Genban; Yang, Xiaojing; Kanatzidis, Mercouri G

    2015-03-18

    There is a need to develop highly selective and efficient materials for capturing uranium (normally as UO2(2+)) from nuclear waste and from seawater. We demonstrate the promising adsorption performance of S(x)-LDH composites (LDH is Mg/Al layered double hydroxide, [S(x)](2-) is polysulfide with x = 2, 4) for uranyl ions from a variety of aqueous solutions including seawater. We report high removal capacities (q(m) = 330 mg/g), large K(d)(U) values (10(4)-10(6) mL/g at 1-300 ppm U concentration), and high % removals (>95% at 1-100 ppm, or ∼80% for ppb level seawater) for UO2(2+) species. The S(x)-LDHs are exceptionally efficient for selectively and rapidly capturing UO2(2+) both at high (ppm) and trace (ppb) quantities from the U-containing water including seawater. The maximum adsorption coeffcient value K(d)(U) of 3.4 × 10(6) mL/g (using a V/m ratio of 1000 mL/g) observed is among the highest reported for U adsorbents. In the presence of very high concentrations of competitive ions such as Ca(2+)/Na(+), S(x)-LDH exhibits superior selectivity for UO2(2+), over previously reported sorbents. Under low U concentrations, (S4)(2-) coordinates to UO2(2+) forming anionic complexes retaining in the LDH gallery. At high U concentrations, (S4)(2-) binds to UO2(2+) to generate neutral UO2S4 salts outside the gallery, with NO3(-) entering the interlayer to form NO3-LDH. In the presence of high Cl(-) concentration, Cl(-) preferentially replaces [S4](2-) and intercalates into LDH. Detailed comparison of U removal efficiency of S(x)-LDH with various known sorbents is reported. The excellent uranium adsorption ability along with the environmentally safe, low-cost constituents points to the high potential of S(x)-LDH materials for selective uranium capture. PMID:25714654

  15. Layered double hydroxide nanoparticles as cellular delivery vectors of supercoiled plasmid DNA.

    PubMed

    Xu, Zhi Ping; Walker, Tara L; Liu, Kerh-lin; Cooper, Helen M; Lu, G Q Max; Bartlett, Perry F

    2007-01-01

    We prepared stable homogeneous suspensions with layered double hydroxide (LDH) nanoparticles for in vitro gene delivery tests. The viability of HEK 293T cells in the presence of LDH nanoparticles at different concentrations was investigated. This revealed 50% cell viability at 500 microg/mL of LDH nanoparticles that is much higher than 50-100 microg/mL used for the delivery tests. The supercoiled pEF-eGFP plasmid (ca. 6100 base pairs) was mixed with LDH nanoparticle suspensions for anion exchange at a weight ratio of DNA/LDH between 1:25 and 1:100. In vitro experiments show that GFP expression in HEK 293T cells starts in the first day, reaches the maximum levels by the second day and continues in the third day. The GFP expression generally increases with the increase in DNA loading in DNA-LDH nanohybrids. However, the delivery efficiency with LDH nanoparticles as the agent is low. For example, the relative efficiency is 7%-15% of that of the commercial agent FuGENE 6. Three to 6% of total cells expressed GFP in an amount detectable by the FACS cytometry 2 days after transfection at 1 microg/mL of plasmid DNA with 25 microg/mL of LDH nanomaterial. The lower delivery efficiency could be attributed to the aggregation of LDH nanoparticles caused by the long-chain plasmid DNA. PMID:17722544

  16. Bionanocomposites based on layered double hydroxides as drug delivery systems

    NASA Astrophysics Data System (ADS)

    Aranda, Pilar; Alcântara, Ana C. S.; Ribeiro, Ligia N. M.; Darder, Margarita; Ruiz-Hitzky, Eduardo

    2012-10-01

    The present work introduces new biohybrid materials involving layered double hydroxides (LDH) and biopolymers to produce bionanocomposites, able to act as effective drug delivery systems (DDS). Ibuprofen (IBU) and 5-aminosalicylic acid (5-ASA) have been chosen as model drugs, being intercalated in a Mg-Al LDH matrix. On the one side, the LDHIBU intercalation compound prepared by ion-exchange reaction was blended with the biopolymers zein, a highly hydrophobic protein, and alginate, a polysaccharide widely applied for encapsulating drugs. On the other side, the LDH- 5-ASA intercalation compound prepared by co-precipitation was assembled to the polysaccharides chitosan and pectin, which show mucoadhesive properties and resistance to acid pH values, respectively. Characterization of the intercalation compounds and the resulting bionanocomposites was carried out by means of different experimental techniques: X-ray diffraction, infrared spectroscopy, chemical and thermal analysis, as well as optical and scanning electron microscopies. Data on the swelling behavior and drug release under different pH conditions are also reported.

  17. Cadmium-Aluminum Layered Double Hydroxide Microspheres for Photocatalytic CO2 Reduction.

    PubMed

    Saliba, Daniel; Ezzeddine, Alaa; Sougrat, Rachid; Khashab, Niveen M; Hmadeh, Mohamad; Al-Ghoul, Mazen

    2016-04-21

    We report the synthesis of cadmium-aluminum layered double hydroxide (CdAl LDH) using the reaction-diffusion framework. As the hydroxide anions diffuse into an agar gel matrix containing the mixture of aluminum and cadmium salts at a given ratio, they react to give the LDH. The LDH self-assembles inside the pores of the gel matrix into a unique spherical-porous shaped microstructure. The internal and external morphologies of the particles are studied by electron microscopy and tomography revealing interconnected channels and a high surface area. This material is shown to exhibit a promising performance in the photoreduction of carbon dioxide using solar light. Moreover, the palladium-decorated version shows a significant improvement in its reduction potential at room temperature. PMID:27028104

  18. Chelator-Free Labeling of Layered Double Hydroxide Nanoparticles for in Vivo PET Imaging

    NASA Astrophysics Data System (ADS)

    Shi, Sixiang; Fliss, Brianne C.; Gu, Zi; Zhu, Yian; Hong, Hao; Valdovinos, Hector F.; Hernandez, Reinier; Goel, Shreya; Luo, Haiming; Chen, Feng; Barnhart, Todd E.; Nickles, Robert J.; Xu, Zhi Ping; Cai, Weibo

    2015-11-01

    Layered double hydroxide (LDH) nanomaterial has emerged as a novel delivery agent for biomedical applications due to its unique structure and properties. However, in vivo positron emission tomography (PET) imaging with LDH nanoparticles has not been achieved. The aim of this study is to explore chelator-free labeling of LDH nanoparticles with radioisotopes for in vivo PET imaging. Bivalent cation 64Cu2+ and trivalent cation 44Sc3+ were found to readily label LDH nanoparticles with excellent labeling efficiency and stability, whereas tetravalent cation 89Zr4+ could not label LDH since it does not fit into the LDH crystal structure. PET imaging shows that prominent tumor uptake was achieved in 4T1 breast cancer with 64Cu-LDH-BSA via passive targeting alone (7.7 ± 0.1%ID/g at 16 h post-injection; n = 3). These results support that LDH is a versatile platform that can be labeled with various bivalent and trivalent radiometals without comprising the native properties, highly desirable for PET image-guided drug delivery.

  19. Chelator-Free Labeling of Layered Double Hydroxide Nanoparticles for in Vivo PET Imaging

    PubMed Central

    Shi, Sixiang; Fliss, Brianne C.; Gu, Zi; Zhu, Yian; Hong, Hao; Valdovinos, Hector F.; Hernandez, Reinier; Goel, Shreya; Luo, Haiming; Chen, Feng; Barnhart, Todd E.; Nickles, Robert J.; Xu, Zhi Ping; Cai, Weibo

    2015-01-01

    Layered double hydroxide (LDH) nanomaterial has emerged as a novel delivery agent for biomedical applications due to its unique structure and properties. However, in vivo positron emission tomography (PET) imaging with LDH nanoparticles has not been achieved. The aim of this study is to explore chelator-free labeling of LDH nanoparticles with radioisotopes for in vivo PET imaging. Bivalent cation 64Cu2+ and trivalent cation 44Sc3+ were found to readily label LDH nanoparticles with excellent labeling efficiency and stability, whereas tetravalent cation 89Zr4+ could not label LDH since it does not fit into the LDH crystal structure. PET imaging shows that prominent tumor uptake was achieved in 4T1 breast cancer with 64Cu-LDH-BSA via passive targeting alone (7.7 ± 0.1%ID/g at 16 h post-injection; n = 3). These results support that LDH is a versatile platform that can be labeled with various bivalent and trivalent radiometals without comprising the native properties, highly desirable for PET image-guided drug delivery. PMID:26585551

  20. Micrometer-Thick Graphene Oxide-Layered Double Hydroxide Nacre-Inspired Coatings and Their Properties.

    PubMed

    Yan, You-Xian; Yao, Hong-Bin; Mao, Li-Bo; Asiri, Abdullah M; Alamry, Khalid A; Marwani, Hadi M; Yu, Shu-Hong

    2016-02-10

    Robust, functional, and flame retardant coatings are attractive in various fields such as building construction, food packaging, electronics encapsulation, and so on. Here, strong, colorful, and fire-retardant micrometer-thick hybrid coatings are reported, which can be constructed via an enhanced layer-by-layer assembly of graphene oxide (GO) nanosheets and layered double hydroxide (LDH) nanoplatelets. The fabricated GO-LDH hybrid coatings show uniform nacre-like layered structures that endow them good mechanic properties with Young's modulus of ≈ 18 GPa and hardness of ≈ 0.68 GPa. In addition, the GO-LDH hybrid coatings exhibit nacre-like iridescence and attractive flame retardancy as well due to their well-defined 2D microstructures. This kind of nacre-inspired GO-LDH hybrid thick coatings will be applied in various fields in future due to their high strength and multifunctionalities. PMID:26682698

  1. Layered Double Hydroxide Nanoclusters: Aqueous, Concentrated, Stable, and Catalytically Active Colloids toward Green Chemistry.

    PubMed

    Tokudome, Yasuaki; Morimoto, Tsuyoshi; Tarutani, Naoki; Vaz, Pedro D; Nunes, Carla D; Prevot, Vanessa; Stenning, Gavin B G; Takahashi, Masahide

    2016-05-24

    Increasing attention has been dedicated to the development of nanomaterials rendering green and sustainable processes, which occur in benign aqueous reaction media. Herein, we demonstrate the synthesis of another family of green nanomaterials, layered double hydroxide (LDH) nanoclusters, which are concentrated (98.7 g/L in aqueous solvent), stably dispersed (transparent sol for >2 weeks), and catalytically active colloids of nano LDHs (isotropic shape with the size of 7.8 nm as determined by small-angle X-ray scattering). LDH nanoclusters are available as colloidal building blocks to give access to meso- and macroporous LDH materials. Proof-of-concept applications revealed that the LDH nanocluster works as a solid basic catalyst and is separable from solvents of catalytic reactions, confirming the nature of nanocatalysts. The present work closely investigates the unique physical and chemical features of this colloid, the formation mechanism, and the ability to act as basic nanocatalysts in benign aqueous reaction systems. PMID:27124717

  2. Nanohybrids of Mg/Al layered double hydroxide and long-chain (C18) unsaturated fatty acid anions: Structure and sorptive properties

    Technology Transfer Automated Retrieval System (TEKTRAN)

    Long-chain (C18) unsaturated fatty acid anions, elaidate (ELA), oleate (OLE), linoleate (LINO), and linolenate (LINOLEN), were intercalated into Mg/Al (3:1) layered double hydroxide (LDH) and the resultant organo-LDH nanohybrid materials were characterized and subsequently evaluated as sorbents of s...

  3. Enhanced thermal- and photo-stability of acid yellow 17 by incorporation into layered double hydroxides

    SciTech Connect

    Wang Qian; Feng Yongjun; Feng Junting; Li Dianqing

    2011-06-15

    2,5-dichloro-4-(5-hydroxy-3-methyl-4-(sulphophenylazo) pyrazol-1-yl) benzenesulphonate (DHSB) anions, namely acid yellow 17 anions, have been successfully intercalated into Zn-Al layered double hydroxides (LDH) to produce a novel organic-inorganic pigment by a simple method involving separate nucleation and aging steps (SNAS), and the dye-intercalated LDH was analyzed by various techniques, e.g., XRD, SEM, FT-IR, TG-DTA and ICP. The d-spacing of the prepared LDH is 2.09 nm. Furthermore, the incorporation of the DHSB aims to enhance the thermal- and photo-stability of the guest dye molecule, for example, the less color change after accelerated thermal- and photo-aging test. - Graphical abstract: Acid yellow anions were successfully assembled into ZnAl layered double hydroxides (LDH) to produce a novel organic-inorganic composite pigment by a simple method involving separate nucleation and aging steps (SNAS). Highlights: > Acid yellow 17 was directly intercalated into ZnAl-LDH to form a novel pigment. > The pigment was prepared by a method involving separate nucleation and aging steps. > The intercalation of dye anions enhances its thermal- and photo-stability.

  4. Platelets to rings: Influence of sodium dodecyl sulfate on Zn-Al layered double hydroxide morphology

    SciTech Connect

    Yilmaz, Ceren; Unal, Ugur; Yagci Acar, Havva

    2012-03-15

    In the current study, influence of sodium dodecyl sulfate (SDS) on the crystallization of Zn-Al layered double hydroxide (LDH) was investigated. Depending on the SDS concentration coral-like and for the first time ring-like morphologies were obtained in a urea-hydrolysis method. It was revealed that the surfactant level in the starting solution plays an important role in the morphology. Concentration of surfactant equal to or above the anion exchange capacity of the LDH is influential in creating different morphologies. Another important parameter was the critical micelle concentration (CMC) of the surfactant. Surfactant concentrations well above CMC value resulted in ring-like structures. The crystallization mechanism was discussed. - Graphical abstract: Dependence of ZnAl LDH Morphology on SDS concentration. Highlights: Black-Right-Pointing-Pointer In-situ intercalation of SDS in ZnAl LDH was achieved via urea hydrolysis method. Black-Right-Pointing-Pointer Morphology of ZnAl LDH intercalated with SDS depended on the SDS concentration. Black-Right-Pointing-Pointer Ring like morphology for SDS intercalated ZnAl LDH was obtained for the first time. Black-Right-Pointing-Pointer Growth mechanism was discussed. Black-Right-Pointing-Pointer Template assisted growth of ZnAl LDH was proposed.

  5. Calcined Mg-Fe layered double hydroxide as an absorber for the removal of methyl orange

    NASA Astrophysics Data System (ADS)

    Peng, Chao; Dai, Jing; Yu, Jianying; Yin, Jian

    2015-05-01

    In this work, methyl orange (MO) was effectively removed from aqueous solution with the calcined product of hydrothermal synthesized Mg/Fe layered double hydroxide (Mg/Fe-LDH). The structure, composition, morphology and textural properties of the Mg/Fe-LDH before and after adsorption were characterized by X-ray diffraction, Fourier transformation infrared spectroscopy, transmission electron microscopy, nitrogen adsorption apparatus and X-ray photoelectron spectroscopy. It was confirmed that MO had been absorbed by calcined Mg/Fe-LDH which had strong interactions with MO. The adsorption of MO onto the Mg/Fe-LDH was systematically investigated by batch tests. The adsorption capacity of the Mg/Fe-LDH toward MO was found to be 194.9 mg • g-1. Adsorption kinetics and isotherm studies revealed that the adsorption of MO onto Mg/Fe-LDH was a spontaneous and endothermic process. These results indicate that Mg/Fe-LDH is a promising material for the removal of MO.

  6. Crosslinking to enhance colloidal stability and redispersity of layered double hydroxide nanoparticles.

    PubMed

    Zuo, Huali; Gu, Zi; Cooper, Helen; Xu, Zhi Ping

    2015-12-01

    This article introduces a strategy for stabilizing and redispersing layered double hydroxide (LDH) nanoparticles by crosslinking bovine serum albumin (BSA) coated onto the surface. The strategy involves optimization of the amount of the crosslinking agent glutaraldehyde (GTA) to achieve minimal aggregation and ready redispersion. LDH nanoparticles were prepared by co-precipitation and hydrothermal treatment, with subsequent BSA coating at the BSA/LDH mass ratio of 5:2. BSA coated onto LDH nanoparticles was crosslinked with different amounts of GTA. Aggregation studies using dilution assays, dynamic light scattering, and zeta potential analysis indicated that severe aggregation at lower LDH nanoparticle concentrations can be prevented by proper crosslinking of BSA with GTA. The GTA-crosslinked BSA-coated nanoparticles showed excellent redispersity compared to the non-crosslinked nanoparticles. In vitro cytotoxicity and cell uptake were found to be minimally affected by GTA-crosslinking. The new strategy therefore provides a much more effective method for the prevention of LDH nanoparticle aggregation and improved LDH nanoparticle redispersion for use in a wide variety of bio-applications in vitro and in vivo. PMID:26254867

  7. Calcined Mg-Fe layered double hydroxide as an absorber for the removal of methyl orange

    SciTech Connect

    Peng, Chao; Dai, Jing; Yu, Jianying; Yin, Jian

    2015-05-15

    In this work, methyl orange (MO) was effectively removed from aqueous solution with the calcined product of hydrothermal synthesized Mg/Fe layered double hydroxide (Mg/Fe-LDH). The structure, composition, morphology and textural properties of the Mg/Fe-LDH before and after adsorption were characterized by X-ray diffraction, Fourier transformation infrared spectroscopy, transmission electron microscopy, nitrogen adsorption apparatus and X-ray photoelectron spectroscopy. It was confirmed that MO had been absorbed by calcined Mg/Fe-LDH which had strong interactions with MO. The adsorption of MO onto the Mg/Fe-LDH was systematically investigated by batch tests. The adsorption capacity of the Mg/Fe-LDH toward MO was found to be 194.9 mg • g{sup −1}. Adsorption kinetics and isotherm studies revealed that the adsorption of MO onto Mg/Fe-LDH was a spontaneous and endothermic process. These results indicate that Mg/Fe-LDH is a promising material for the removal of MO.

  8. Tuneable ultra high specific surface area Mg/Al-CO3 layered double hydroxides.

    PubMed

    Chen, Chunping; Wangriya, Aunchana; Buffet, Jean-Charles; O'Hare, Dermot

    2015-10-01

    We report the synthesis of tuneable ultra high specific surface area Aqueous Miscible Organic solvent-Layered Double Hydroxides (AMO-LDHs). We have investigated the effects of different solvent dispersion volumes, dispersion times and the number of re-dispersion cycles specific surface area of AMO-LDHs. In particular, the effects of acetone dispersion on two different morphology AMO-LDHs (Mg3Al-CO3 AMO-LDH flowers and Mg3Al-CO3 AMO-LDH plates) was investigated. It was found that the amount of acetone used in the dispersion step process can significantly affect the specific surface area of Mg3Al-CO3 AMO-LDH flowers while the dispersion time in acetone is critical factor to obtain high specific surface area Mg3Al-CO3 AMO-LDH plates. Optimisation of the acetone washing steps enables Mg3Al-CO3 AMO-LDH to have high specific surface area up to 365 m(2) g(-1) for LDH flowers and 263 m(2) g(-1) for LDH plates. In addition, spray drying was found to be an effective and practical drying method to increase the specific surface area by a factor of 1.75. Our findings now form the basis of an effective general strategy to obtain ultrahigh specific surface area LDHs. PMID:26308729

  9. Rearrangement of layered double hydroxide nanoplatelets during hollow colloidosome preparation.

    PubMed

    Liu, Guopeng; Liu, Shangying; Dong, Xiaoqiang; Yang, Fei; Sun, Dejun

    2010-05-15

    Hollow colloidosomes consisting of plate-like Mg/Al layered double hydroxide (LDH) nanoparticles have been prepared by a facile route from a Pickering emulsion. The particles are first adsorbed onto the surface of paraffin oil-in-water emulsion droplets. After the core oil is dissolved in the surrounding bulk liquid, using solvents that are miscible with both the internal and external phases of the droplets, colloidosomes are formed. In this process, we find that the diameters of the colloidosomes are significantly reduced compared to those of the emulsion droplets. The reduction in the diameter is caused by rearrangement of the LDH platelets. That is, the platelets change their orientation from lying flat on the emulsion droplet surface to standing erect in a dense, face-to-face connecting pattern in the colloidosome shell. The main reason for the particle rearrangement is the increase of the attractive forces among the particles due to the reduced polarity of the solvents used during colloidosome preparation. PMID:20219203

  10. Large-scale synthesis of highly dispersed layered double hydroxide powders containing delaminated single layer nanosheets.

    PubMed

    Wang, Qiang; O'Hare, Dermot

    2013-07-18

    A facile method for the synthesis of Zn2Al-borate and Mg3Al-borate layered double hydroxides (LDHs) with extremely high specific surface areas of 458.6 and 263 m(2) g(-1) and containing delaminated nanosheets is reported. To the best of our knowledge, this is the first report of LDH powders that still remain exfoliated on drying. PMID:23739826

  11. The use of layered double hydroxides as DNA vaccine delivery vector for enhancement of anti-melanoma immune response.

    PubMed

    Li, Ang; Qin, Lili; Wang, Wenrui; Zhu, Rongrong; Yu, Yongchun; Liu, Hui; Wang, Shilong

    2011-01-01

    Our previous studies have shown that Mg:Al 1:1 layered double hydroxides (LDH(R1)) nanoparticles could be taken up by the MDDCs effectively and had an adjuvant activity for DC maturation. Furthermore, these LDH(R1) nanoparticles could up-regulate the expression of CCR7 and augment the migration of DCs in response to CCL21. In current study, we have evaluated whether LDH(R1) as DNA vaccine delivery carrier can augment the efficacy of DNA vaccine immunization in vivo. Firstly, we found that LDH(R1) was efficient in combining DNA and formed LDH(R1)/DNA complex with an average diameter of about 80-120 nm. Its high transfection efficiency in vivo delivered with a GFP expression plasmid was also observed. After delivery of pcDNA(3)-OVA/LDH(R1) complex by intradermal immunization in C57BL/6 mice, the LDH(R1) induced an enhanced serum antibody response much greater than naked DNA vaccine. Using B16-OVA melanoma as tumor model, we demonstrated that pcDNA(3)-OVA/LDH(R1) complex enhanced immune priming and protection from tumor challenge in vivo. Furthermore, we showed that LDH(R1) induced dramatically more effective CTL activation and skewed T helper polarization to Th1. Collectively, these findings demonstrate that this LDH(R1)/DNA plasmid complex should be a new and promising way in vaccination against tumor. PMID:20934217

  12. Hierarchical construction of an ultrathin layered double hydroxide nanoarray for highly-efficient oxygen evolution reaction

    NASA Astrophysics Data System (ADS)

    Yang, Qiu; Li, Tian; Lu, Zhiyi; Sun, Xiaoming; Liu, Junfeng

    2014-09-01

    Efficient and low-cost electrocatalysts for the oxygen evolution reaction (OER) are essential components of renewable energy technologies, such as solar fuel synthesis and water splitting processes for powering fuel cells. Here, ultrathin NiCoFe layered double hydroxide (LDH) nanoplates, which directly grow on a cobalt-based nanowire array, forming a hierarchical nanoarray structure, are constructed as efficient oxygen evolution electrodes. In alkaline media, the ordered ultrathin hierarchical LDH nanoarray electrode shows dramatically increased catalytic activity compared to that of LDH nanoparticles and pure nanowire arrays due to the small size, large surface area, and high porosity of the NiCoFe LDH nanoarray. Only a small water oxidation overpotential (η) of 257 mV is needed for a current density of 80 mA cm-2 with a Tafel slope of 53 mV per decade. The hierarchical LDH nanoarray also shows excellent structural stability in alkaline media. After continuous testing under a high OER current density (~300 mA cm-2) for 10 h, the sample maintains the ordered hierarchical structure with no significant deactivation of the catalytic properties.Efficient and low-cost electrocatalysts for the oxygen evolution reaction (OER) are essential components of renewable energy technologies, such as solar fuel synthesis and water splitting processes for powering fuel cells. Here, ultrathin NiCoFe layered double hydroxide (LDH) nanoplates, which directly grow on a cobalt-based nanowire array, forming a hierarchical nanoarray structure, are constructed as efficient oxygen evolution electrodes. In alkaline media, the ordered ultrathin hierarchical LDH nanoarray electrode shows dramatically increased catalytic activity compared to that of LDH nanoparticles and pure nanowire arrays due to the small size, large surface area, and high porosity of the NiCoFe LDH nanoarray. Only a small water oxidation overpotential (η) of 257 mV is needed for a current density of 80 mA cm-2 with a

  13. Enhancement of the coercivity in Co-Ni layered double hydroxides by increasing basal spacing.

    PubMed

    Zhang, Cuijuan; Tsuboi, Tomoya; Namba, Hiroaki; Einaga, Yasuaki; Yamamoto, Takashi

    2016-09-14

    The magnetic properties of layered double hydroxides (LDH) containing transition metal ions can still develop, compared with layered metal hydroxide salts which exhibit structure-dependent magnetism. In this article, we report the preparation of a hybrid magnet composed of Co-Ni LDH and n-alkylsulfonate anions (Co-Ni-CnSO3 LDH). As Co-Ni LDH is anion-exchangeable, we can systematically control the interlayer spacing by intercalating n-alkylsulfonates with different carbon numbers. The magnetic properties were examined with temperature- and field-dependent magnetization measurements. As a result, we have revealed that the coercive field depends on the basal spacing. It is suggested that increasing the basal spacing varies the competition between the in-plane superexchange interactions and long-range out-of-plane dipolar interactions. Moreover, a jump in the coercive field at around 20 Å of the basal spacing is assumed to be the modification of the magnetic ordering in Co-Ni-CnSO3 LDH. PMID:27381282

  14. Reversible color changes in lamella hybrids of poly(diacetylenecarboxylates) incorporated in layered double hydroxide nanosheets.

    PubMed

    Itoh, Toshio; Shichi, Tetsuya; Yui, Tatsuto; Takahashi, Hiroki; Inui, Yoshihisa; Takagi, Katsuhiko

    2005-03-01

    The present study is an investigation of a reversible thermal color change induced in lamella hybrids of poly(diacetylenecarboxylates) incorporated in layered double hydroxide (LDH) nanosheets. These poly-[m,n]/LDH hybrids prepared by the photo- or gamma-ray-induced polymerization of diacetylenecarboxylates, i.e., CH(3)(CH(2))(m)()(-)(1)CC-CC(CH(2))(n)()(-)(1)CO(2)(-) (mono-[m,n]), and intercalated in LDH lamella sheets, were observed to develop colors ranging from yellow to blue. The change in color was found to depend greatly on the alkyl carbon numbers of the mono-[m,n] (m,n = 10,11; 5,11; 10,5; 16,1) values. Moreover, the conformational alignment of the mono-[m,n] within the LDH was observed to be a crucial factor in color development, which was greatly affected by the intercalation degrees and extent of poly(ene-yne) linkage elongation of the polymers. For the poly-[m,n]/LDH hybrids investigated, a reversible color change was found to occur repeatedly and remarkably for the poly-[10,11]/LDH hybrid. This color change occurred at temperatures between ca. 20 and 80 degrees C back and forth from purple red to bright orange, in stark contrast to the irreversible color change for poly-[10,11] without LDH. Moreover, DSC and Raman spectroscopic studies of the LDH hybrids showed that the thermochromic temperature corresponded to the phase transition temperature of 80 degrees C. XRD analysis also indicated that the poly-[m,n]/LDH hybrid could retain its lamella structure during such thermochromic color changes, enabling conformational recovery in the polymer chains by a cooling down of the hybrids to temperatures lower than the transition temperature, while the nonhybrid poly-[10,11] powders exhibited an irreversible color change at 60 degrees C, above which the polymer powder turned amorphous. PMID:16851341

  15. Eu-doped Mg-Al layered double hydroxide as a responsive fluorescent material and its interaction with glutamic acid

    NASA Astrophysics Data System (ADS)

    Chen, Yufeng; Li, Fei; Yu, Gensheng; Wei, Junchao

    2012-10-01

    The paper describes a study on the fluorescence of a Eu-doped Mg-Al layered double hydroxide (Eu-doped LDH) response to glutamic acid (Glu). Various characterizations (UV-Vis transmittance, TG-DTA and IR-spectrum) indicated that there is an interaction between the Eu-doped LDH and Glu. Fluorescent study was found that the red emissions resulted from 5D0-7FJ transition (J = 1, 2) of Eu3+ markedly decreased, while the blue emission at 440 nm contributed to Glu shifted to low energy after the addition of Glu to the Eu-doped LDH. The fluorescent changes may be relevant to the hydrogen-bond interaction between the Eu-doped LDH and Glu, and the mechanism of the interaction between Eu-doped LDH and Glu was discussed.

  16. Enhanced catalytic oxidation ability of ternary layered double hydroxides for organic pollutants degradation.

    PubMed

    Fahel, Jean; Kim, Sanghoon; Durand, Pierrick; André, Erwan; Carteret, Cédric

    2016-05-10

    Co(2+) and Cu(2+) substituted MgAl layered double hydroxides with an M(2+)/M(3+) atomic ratio of 2.0 were synthesized by a co-precipitation method and fully characterized using various techniques including powder X-ray diffraction, ICP-AES analysis, FT-IR, DR UV-Vis spectroscopy, N2 adsorption-desorption and transmission electron microscopy. The materials revealed a good crystallinity with no phase impurity and successful substitution of cobalt and copper ions in the framework of binary LDH with the target ratio of metals in the sheet. The adsorption characteristics (kinetic and isotherm) and the catalytic oxidation of organic pollutants, methylene blue (cationic dye) and orange II (anionic) were carried out to investigate a potential use of LDH materials as catalysts. In particular, Co3Cu1Al2 LDH exhibited an excellent catalytic activity towards catalytic dye degradation, especially for orange II with good stability and reusability over several times. Furthermore, this LDH material showed good catalytic performance for several chlorophenol compounds, suggesting its practical application in wastewater treatment. Therefore, layered double hydroxides substituted with Co(2+) and Cu(2+) could be promising candidates in various applications, such as the abatement of organic pollutants. PMID:27097543

  17. Tungstocobaltate-pillared layered double hydroxides: Preparation, characterization, magnetic and catalytic properties

    SciTech Connect

    Wei Xiaocui; Fu Youzhi; Xu Lin Li Fengyan; Bi Bo; Liu Xizheng

    2008-06-15

    A new polyoxometalate anion-pillared layered double hydroxide (LDH) was prepared by aqueous ion exchange of a Mg-Al LDH precursor in nitrate form with the tungstocobaltate anions [CoW{sub 12}O{sub 40}]{sup 5-}. The physicochemical properties of the product were characterized by the methods of powder X-ray diffraction, elemental analysis, infrared spectroscopy, thermogravimetric analysis and cyclic voltammetry. It was confirmed that [CoW{sub 12}O{sub 40}]{sup 5-} was intercalated between the brucite-type layers of the LDHs without a change in the structure. Magnetic measurement shows the occurrence of antiferromagnetic interactions between the magnetic centers. The investigation of catalytic performance for this sample exhibits high activity for the oxidation of benzaldehyde by hydrogen peroxide. - Graphical abstract: A tungstocobaltate anion [CoW{sub 12}O{sub 40}]{sup 5-} pillared layered double hydroxide (LDH) was prepared by aqueous ion exchange with a Mg-Al LDH precursor in nitrate form, demonstrating that [CoW{sub 12}O{sub 40}]{sup 5-} was intercalated between the brucite-type layers of the LDHs without change in structure. Magnetic measurement shows the occurrence of antiferromagnetic interactions between the magnetic centers. The investigation of catalytic performance for this sample exhibits high activity for the oxidation of benzaldehyde by hydrogen peroxide.

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

    PubMed

    Nakagaki, Shirley; Halma, Matilte; Bail, Alesandro; Arízaga, Gregório Guadalupe Carbajal; Wypych, Fernando

    2005-01-15

    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. PMID:15571697

  19. High pseudocapacitive cobalt carbonate hydroxide films derived from CoAl layered double hydroxides

    NASA Astrophysics Data System (ADS)

    Lu, Zhiyi; Zhu, Wei; Lei, Xiaodong; Williams, Gareth R.; O'Hare, Dermot; Chang, Zheng; Sun, Xiaoming; Duan, Xue

    2012-05-01

    A thin nanosheet of mesoporous cobalt carbonate hydroxide (MPCCH) has been fabricated from a CoAl-LDH nanosheet following removal of the Al cations by alkali etching. The basic etched electrode exhibits enhanced specific capacitance (1075 F g-1 at 5 mA cm-2) and higher rate capability and cycling stability (92% maintained after 2000 cycles).A thin nanosheet of mesoporous cobalt carbonate hydroxide (MPCCH) has been fabricated from a CoAl-LDH nanosheet following removal of the Al cations by alkali etching. The basic etched electrode exhibits enhanced specific capacitance (1075 F g-1 at 5 mA cm-2) and higher rate capability and cycling stability (92% maintained after 2000 cycles). Electronic supplementary information (ESI) available: Detailed experimental procedure, specific capacitance calculation, EDS and FTIR results, electrochemical results of CoAl-LDH and SEM image. See DOI: 10.1039/c2nr30617d

  20. Layered double hydroxide stability. 2. Formation of Cr(III)-containing layered double hydroxides directly from solution

    NASA Technical Reports Server (NTRS)

    Boclair, J. W.; Braterman, P. S.; Jiang, J.; Lou, S.; Yarberry, F.

    1999-01-01

    Solutions containing divalent metal [M(II) = Mg2+, Zn2+, Co2+, Ni2+, Mn2+] chlorides and CrCl3 6H2O were titrated with NaOH to yield, for M(II) = Zn, Co, and Ni, hydrotalcite-like layered double hydroxides (LDHs), [[M(II)]1-z[Cr(III)]z(OH)2][Cl]z yH2O, in a single step, without intermediate formation of chromium hydroxide. Analysis of the resultant titration curves yields solubility constants for these compounds. These are in the order Zn < Ni approximately Co, with a clear preference for formation of the phase with z = 1/3. With Mg2+ as chloride, titration gives a mixture of Cr(OH)3 and Mg(OH)2, but the metal sulfates give Mg2Cr(OH)6 1/2(SO4) by a two-step process. Titrimetric and spectroscopic evidence suggests short-range cation order in the one-step LDH systems.

  1. Intercalation and controlled release properties of vitamin C intercalated layered double hydroxide

    NASA Astrophysics Data System (ADS)

    Gao, Xiaorui; Lei, Lixu; O'Hare, Dermot; Xie, Juan; Gao, Pengran; Chang, Tao

    2013-07-01

    Two drug-inorganic composites involving vitamin C (VC) intercalated in Mg-Al and Mg-Fe layered double hydroxides (LDHs) have been synthesized by the calcination-rehydration (reconstruction) method. Powder X-ray diffraction (XRD), Fourier transform infrared (FTIR), and UV-vis absorption spectroscopy indicate a successful intercalation of VC into the interlayer galleries of the LDH host. Studies of VC release from the LDHs in deionised water and in aqueous CO32- solutions imply that Mg3Al-VC LDH is a better controlled release system than Mg3Fe-VC LDH. Analysis of the release profiles using a number of kinetic models suggests a solution-dependent release mechanism, and a diffusion-controlled deintercalation mechanism in deionised water, but an ion exchange process in CO32- solution.

  2. Large Scale Synthesis of NiCo Layered Double Hydroxides for Superior Asymmetric Electrochemical Capacitor

    PubMed Central

    Li, Ruchun; Hu, Zhaoxia; Shao, Xiaofeng; Cheng, Pengpeng; Li, Shoushou; Yu, Wendan; Lin, Worong; Yuan, Dingsheng

    2016-01-01

    We report a new environmentally-friendly synthetic strategy for large-scale preparation of 16 nm-ultrathin NiCo based layered double hydroxides (LDH). The Ni50Co50-LDH electrode exhibited excellent specific capacitance of 1537 F g−1 at 0.5 A g−1 and 1181 F g−1 even at current density as high as 10 A g−1, which 50% cobalt doped enhances the electrical conductivity and porous and ultrathin structure is helpful with electrolyte diffusion to improve the material utilization. An asymmetric ultracapacitor was assembled with the N-doped graphitic ordered mesoporous carbon as negative electrode and the NiCo LDH as positive electrode. The device achieves a high energy density of 33.7 Wh kg−1 (at power density of 551 W kg−1) with a 1.5 V operating voltage. PMID:26754281

  3. Thin bacteria/Layered Double Hydroxide films using a layer-by-layer approach.

    PubMed

    Halma, Matilte; Khenifi, Aicha; Sancelme, Martine; Besse-Hoggan, Pascale; Bussière, Pierre-Olivier; Prévot, Vanessa; Mousty, Christine

    2016-07-15

    This paper reports the design of thin bacteria/Layered Double Hydroxides (LDH) films in which bacterial cells of Pseudomonas sp. strain ADP were assembled alternatively with Mg2Al-NO3 LDH nanosheets by a layer-by-layer deposition method. The UV-Vis spectroscopy was used to monitor the assembly process, showing a progressive increase in immobilized bacteria amount upon deposited cycles. The {ADP/LDH}n film was characterized by X-ray diffraction, infrared spectroscopy, scanning electron microscopy and atomic force microscopy. The metabolic activity of immobilized bacteria was determined using chronoamperometry by measuring the biochemical oxygen demand in presence of glucose using an artificial electron acceptor (Fe(CN)6(3-)) at 0.5V/Ag-AgCl. A steady current of 0.250μAcm(-2) was reached in about 30s after the addition of 5mM glucose. PMID:27124809

  4. Large Scale Synthesis of NiCo Layered Double Hydroxides for Superior Asymmetric Electrochemical Capacitor.

    PubMed

    Li, Ruchun; Hu, Zhaoxia; Shao, Xiaofeng; Cheng, Pengpeng; Li, Shoushou; Yu, Wendan; Lin, Worong; Yuan, Dingsheng

    2016-01-01

    We report a new environmentally-friendly synthetic strategy for large-scale preparation of 16 nm-ultrathin NiCo based layered double hydroxides (LDH). The Ni50Co50-LDH electrode exhibited excellent specific capacitance of 1537 F g(-1) at 0.5 A g(-1) and 1181 F g(-1) even at current density as high as 10 A g(-1), which 50% cobalt doped enhances the electrical conductivity and porous and ultrathin structure is helpful with electrolyte diffusion to improve the material utilization. An asymmetric ultracapacitor was assembled with the N-doped graphitic ordered mesoporous carbon as negative electrode and the NiCo LDH as positive electrode. The device achieves a high energy density of 33.7 Wh kg(-1) (at power density of 551 W kg(-1)) with a 1.5 V operating voltage. PMID:26754281

  5. Large Scale Synthesis of NiCo Layered Double Hydroxides for Superior Asymmetric Electrochemical Capacitor

    NASA Astrophysics Data System (ADS)

    Li, Ruchun; Hu, Zhaoxia; Shao, Xiaofeng; Cheng, Pengpeng; Li, Shoushou; Yu, Wendan; Lin, Worong; Yuan, Dingsheng

    2016-01-01

    We report a new environmentally-friendly synthetic strategy for large-scale preparation of 16 nm-ultrathin NiCo based layered double hydroxides (LDH). The Ni50Co50-LDH electrode exhibited excellent specific capacitance of 1537 F g-1 at 0.5 A g-1 and 1181 F g-1 even at current density as high as 10 A g-1, which 50% cobalt doped enhances the electrical conductivity and porous and ultrathin structure is helpful with electrolyte diffusion to improve the material utilization. An asymmetric ultracapacitor was assembled with the N-doped graphitic ordered mesoporous carbon as negative electrode and the NiCo LDH as positive electrode. The device achieves a high energy density of 33.7 Wh kg-1 (at power density of 551 W kg-1) with a 1.5 V operating voltage.

  6. Synthesis and photoluminescence of red emitting phosphors of europium complex intercalated layered double hydroxide

    NASA Astrophysics Data System (ADS)

    Gao, Xiaorui; Gao, Zhen; Yin, Xiaoru; Xie, Juan

    2015-12-01

    An inorganic-organic red emitting phosphor, europium ethylenediaminetetraacetate complex ([Eu(EDTA)]-) anions intercalated Mg/Al and Zn/Al layered double hydroxides (LDHs) were synthesized through an ion exchange method. X-ray powder diffraction (XRD) results exhibit that a nearly vertical arrangement of [Eu(EDTA)]- anions with the maximal dimension in the gallery is adopted. Measurement of the excitation and emission spectra show that the two materials display high red luminescence from Eu3+ ions. Furthermore, Mg/Al LDH containing europium complex has higher luminescence intensity than Zn/Al LDH, which probably was related with more inversion asymmetry sites of Eu3+ occurring in the Mg/Al LDH.

  7. Layered Double Hydroxide as a Vehicle to Increase Toxicity of Gallate Ions against Adenocarcinoma Cells.

    PubMed

    Arratia-Quijada, Jenny; Rivas-Fuentes, Selma; Saavedra, Karina J Parra; Lamas, Adriana M Macías; Carbajal Arízaga, Gregorio Guadalupe

    2016-01-01

    The antineoplasic activity of gallic acid has been reported. This compound induces apoptosis and inhibits the growth of several neoplasic cells. However, this molecule is easily oxidized and degraded in the body. The aim of this work was to intercalate gallate ions into layered double hydroxide (LDH) nanoparticles under controlled conditions to reduce oxidation of gallate and to evaluate its toxicity against the A549 adenocarcinoma cell line. An isopropanol medium under nitrogen atmosphere was adequate to intercalate gallate ions with a lesser oxidation degree as detected by electron spin resonance spectroscopy. Concentrations of the hybrid LDH-gallate nanoparticles between 0.39 and 25 µg/mL reduced the cell viability to 67%, while the value reached with the pure gallic acid and LDH was 90% and 78%, respectively, thus proving that the combination of gallate ions with the inorganic nanoparticles increases the toxicity potential within this dose range. PMID:27438820

  8. The construction and characterization of layered double hydroxides as delivery vehicles for podophyllotoxins.

    PubMed

    Xue, Yan Hua; Zhang, Rui; Sun, Xiao Yu; Wang, Shi Long

    2008-03-01

    The aim of this study was to construct PPT-LDH nanohybrids and compare their tumor inhibition effects with that of free PPT. Anticancer drug podophyllotoxin (PPT) was encapsulated in the galleries of Mg-Al layered double hydroxides (LDHs) by a two-step approach. Tyrosine (Tyr) was first incorporated into the interlayer space by co-precipitation with LDH, prop-opening the layers of Mg-Al/LDH and creating an interlayer environment inviting drug molecules. PPT was subsequently intercalated into the resulting material lamella by an ion exchange process. The intermediate and final products, which can be termed drug-inorganic nanocomposites, have been characterized by powder X-ray diffraction (XRD), UV-VIS spectrophotometer, transmission electron microscopy (TEM) and in cell culture. Our results demonstrate that the interlayer spacing distance of the PPT-LDH nanohybrids (34% w/w of drug/material) is 18.2 A. LDHs do not harm normal cells (293T) based on toxicity tests. Ex-vivo anticancer experiments reveal that the PPT-LDH nanohybrids have higher tumor suppression effects than intercalated PPT. We conclude that the higher tumor inhibition effects of PPT-LDH hybrids result from the inorganic drug delivery vehicle, LDHs. PMID:17701296

  9. The in vitro sustained release profile and antitumor effect of etoposide-layered double hydroxide nanohybrids.

    PubMed

    Qin, Lili; Wang, Mei; Zhu, Rongrong; You, Songhui; Zhou, Ping; Wang, Shilong

    2013-01-01

    Magnesium-aluminum layered double hydroxides intercalated with antitumor drug etoposide (VP16) were prepared for the first time using a two-step procedure. The X-ray powder diffraction data suggested the intercalation of VP16 into layers with the increased basal spacing from 0.84-1.18 nm was successful. Then, it was characterized by X-ray powder diffraction, Fourier transform infrared spectroscopy, thermogravimetry and differential thermal analysis, and transmission electron microscopy. The prepared nanoparticles, VP16-LDH, showed an average diameter of 62.5 nm with a zeta potential of 20.5 mV. Evaluation of the buffering effect of VP16-LDH indicated that the nanohybrids were ideal for administration of the drugs that treat human stomach irritation. The loading amount of intercalated VP16 was 21.94% and possessed a profile of sustained release. The mechanism of VP16-LDH release in the phosphate buffered saline solution at pH 7.4 is likely controlled by the diffusion of VP16 anions from inside to the surface of LDH particles. The in vitro cytotoxicity and antitumor assays indicated that VP16-LDH hybrids were less toxic to GES-1 cells while exhibiting better antitumor efficacy on MKN45 and SGC-7901 cells. These results imply that VP16-LDH is a potential antitumor drug for a broad range of gastric cancer therapeutic applications. PMID:23737669

  10. The in vitro sustained release profile and antitumor effect of etoposide-layered double hydroxide nanohybrids

    PubMed Central

    Qin, Lili; Wang, Mei; Zhu, Rongrong; You, Songhui; Zhou, Ping; Wang, Shilong

    2013-01-01

    Magnesium-aluminum layered double hydroxides intercalated with antitumor drug etoposide (VP16) were prepared for the first time using a two-step procedure. The X-ray powder diffraction data suggested the intercalation of VP16 into layers with the increased basal spacing from 0.84–1.18 nm was successful. Then, it was characterized by X-ray powder diffraction, Fourier transform infrared spectroscopy, thermogravimetry and differential thermal analysis, and transmission electron microscopy. The prepared nanoparticles, VP16-LDH, showed an average diameter of 62.5 nm with a zeta potential of 20.5 mV. Evaluation of the buffering effect of VP16-LDH indicated that the nanohybrids were ideal for administration of the drugs that treat human stomach irritation. The loading amount of intercalated VP16 was 21.94% and possessed a profile of sustained release. The mechanism of VP16-LDH release in the phosphate buffered saline solution at pH 7.4 is likely controlled by the diffusion of VP16 anions from inside to the surface of LDH particles. The in vitro cytotoxicity and antitumor assays indicated that VP16-LDH hybrids were less toxic to GES-1 cells while exhibiting better antitumor efficacy on MKN45 and SGC-7901 cells. These results imply that VP16-LDH is a potential antitumor drug for a broad range of gastric cancer therapeutic applications. PMID:23737669

  11. Three-dimensional porous MXene/layered double hydroxide composite for high performance supercapacitors

    NASA Astrophysics Data System (ADS)

    Wang, Ya; Dou, Hui; Wang, Jie; Ding, Bing; Xu, Yunling; Chang, Zhi; Hao, Xiaodong

    2016-09-01

    In this work, an exfoliated MXene (e-MXene) nanosheets/nickel-aluminum layered double hydroxide (MXene/LDH) composite as supercapacitor electrode material is fabricated by in situ growth of LDH on e-MXene substrate. The LDH platelets homogeneously grown on the surface of the e-MXene sheets construct a three-dimensional (3D) porous structure, which not only leads to high active sites exposure of LDH and facile liquid electrolyte penetration, but also alleviates the volume change of LDH during the charge/discharge process. Meanwhile, the e -MXene substrate forms a conductive network to facilitate the electron transport of active material. The optimized MXene/LDH composite exhibits a high specific capacitance of 1061 F g-1 at a current density of 1 A g-1, excellent capacitance retention of 70% after 4000 cycle tests at a current density of 4 A g-1 and a good rate capability with 556 F g-1 retention at 10 A g-1.

  12. Mg-Al layered double hydroxide-methotrexate nanohybrid drug delivery system: evaluation of efficacy.

    PubMed

    Chakraborty, Jui; Roychowdhury, Susanta; Sengupta, Somoshree; Ghosh, Swapankumar

    2013-05-01

    Mg-Al layered double hydroxide nanoparticles were synthesized by one-pot co-precipitation method and anticancerous drug methotrexate was incorporated into it by in-situ ion exchange. The LDH-MTX nanohybrid produced moderately stable suspension in water, as predicted by zeta potential measurement. X-ray diffraction revealed that the basal spacing increased to nearly twice the same for pristine LDH on MTX intercalation. Thermogravimetric analyses confirmed an increase in thermal stability of the intercalated drug in the LDH framework. A striking enhancement in efficacy/sensitivity of MTX on the HCT-116 cells was obtained when intercalated within the LDH layers, as revealed by the attainment of half maximal inhibitory concentration of LDH-MTX nanohybrid by 48 h, whereas, bare MTX required 72 h for the same. The MTX release from MgAl-LDH-MTX hybrids in phosphate buffer saline at pH7.4 followed a relatively slow, first order kinetics and was complete within 8 days following diffusion and crystal dissolution mechanism. PMID:23498245

  13. Intracrystalline structure of DNA molecules stabilized in the layered double hydroxide

    NASA Astrophysics Data System (ADS)

    Oh, Jae-Min; Kwak, Seo-Young; Choy, Jin-Ho

    2006-05-01

    DNA was successfully intercalated into layered double hydroxide (LDH), Mg2Al(OH)6NO3·0.1H2O, through ion exchange reaction to form DNA LDH nanohybrid. Powder X-ray diffraction (PXRD) and fourier-transform infrared (FT-IR) spectroscopic results demonstrate that the DNA molecules are stabilized between the hydroxide layers. According to the circular dichroism (CD) spectroscopic studies, the B-form DNA molecules are electrostatically bound in the interlayer space of LDHs upon satisfying the charge neutralization condition. However, the intercalated DNA molecules are supposed to be more or less twisted due to the charge mismatch between anionic DNA and cationic LDH. To verify the size of DNA strands in the LDH lattice, the DNA molecules with different length of 0.2 5 kbps were intercalated into the LDHs with various particle size. Three kinds of LDHs with discrete particle size were synthesized through both coprecipitation and hydrothermal methods. From the scanning electron microscopy (SEM), the particle sizes were determined as ˜80, 150, and 300 nm, respectively. Thus prepared DNA LDH nanohybrids with various particle size were treated with DNA destroying enzyme such as DNase I. Since the LDHs (80, 150, 300 nm) are smaller in size than the DNA molecules, some parts of the intercalated DNA chains are eventually dangling outside of the host LDH layer. Therefore, the dangling part of DNA chains and the surface adsorbed DNA were decomposed quickly by DNase I treatment. The DNA strands protected by LDH layers could intentionally be recovered by treating with an acidic solution. The length of DNA strands thus recovered were confirmed by electrophoresis, and determined to be ˜200 bps irrespective of the particle size of LDHs.

  14. Ni3+ doped monolayer layered double hydroxide nanosheets as efficient electrodes for supercapacitors

    NASA Astrophysics Data System (ADS)

    Zhao, Yufei; Wang, Qing; Bian, Tong; Yu, Huijun; Fan, Hua; Zhou, Chao; Wu, Li-Zhu; Tung, Chen-Ho; O'Hare, Dermot; Zhang, Tierui

    2015-04-01

    Ni3+ doped NiTi layered double hydroxide (NiTi-LDH) monolayer nanosheets with a particle size of ~20 nm and a thickness of ~0.9 nm have been successfully prepared through a facile bottom-up approach. These NiTi-LDH monolayer nanosheets exhibit excellent supercapacitor performance, including a high specific pseudocapacitance (2310 F g-1 at 1.5 A g-1) and long durability compared with bulk LDH, owing to highly exposed conductive Ni3+ species (NiOOH) which lead to the increased mobility rate of surface charge and electrolyte-transfer. Therefore, this work is expected to take a significant step towards exploring novel 2D monolayer electrode materials with unique physical and chemical properties for applications in energy storage and conversion.Ni3+ doped NiTi layered double hydroxide (NiTi-LDH) monolayer nanosheets with a particle size of ~20 nm and a thickness of ~0.9 nm have been successfully prepared through a facile bottom-up approach. These NiTi-LDH monolayer nanosheets exhibit excellent supercapacitor performance, including a high specific pseudocapacitance (2310 F g-1 at 1.5 A g-1) and long durability compared with bulk LDH, owing to highly exposed conductive Ni3+ species (NiOOH) which lead to the increased mobility rate of surface charge and electrolyte-transfer. Therefore, this work is expected to take a significant step towards exploring novel 2D monolayer electrode materials with unique physical and chemical properties for applications in energy storage and conversion. Electronic supplementary information (ESI) available: Experimental details and additional characterization data. See DOI: 10.1039/c5nr01320h

  15. Coagulation Behavior of Graphene Oxide on Nanocrystallined Mg/Al Layered Double Hydroxides: Batch Experimental and Theoretical Calculation Study.

    PubMed

    Zou, Yidong; Wang, Xiangxue; Ai, Yuejie; Liu, Yunhai; Li, Jiaxing; Ji, Yongfei; Wang, Xiangke

    2016-04-01

    Graphene oxide (GO) has attracted considerable attention because of its remarkable enhanced adsorption and multifunctional properties. However, the toxic properties of GO nanosheets released into the environment could lead to the instability of biological system. In aqueous phase, GO may interact with fine mineral particles, such as chloridion intercalated nanocrystallined Mg/Al layered double hydroxides (LDH-Cl) and nanocrystallined Mg/Al LDHs (LDH-CO3), which are considered as coagulant molecules for the coagulation and removal of GO from aqueous solutions. Herein the coagulation of GO on LDHs were studied as a function of solution pH, ionic strength, contact time, temperature and coagulant concentration. The presence of LDH-Cl and LDH-CO3 improved the coagulation of GO in solution efficiently, which was mainly attributed to the surface oxygen-containing functional groups of LDH-Cl and LDH-CO3 occupying the binding sites of GO. The coagulation of GO by LDH-Cl and LDH-CO3 was strongly dependent on pH and ionic strength. Results of theoretical DFT calculations indicated that the coagulation of GO on LDHs was energetically favored by electrostatic interactions and hydrogen bonds, which was further evidenced by FTIR and XPS analysis. By integrating the experimental results, it was clear that LDH-Cl could be potentially used as a cost-effective coagulant for the elimination of GO from aqueous solutions, which could efficiently decrease the potential toxicity of GO in the natural environment. PMID:26978487

  16. Interlayer interaction in Ca-Fe layered double hydroxides intercalated with nitrate and chloride species

    NASA Astrophysics Data System (ADS)

    Al-Jaberi, Muayad; Naille, Sébastien; Dossot, Manuel; Ruby, Christian

    2015-12-01

    Ca-Fe layered double hydroxide (LDH) intercalated with chloride and nitrate ions has been synthesized with varying CaII:FeIII molar ratios of the initial solution. Phase pure LDH is observed with CaII:FeIII molar ratio of 2:1 and a mixture of LDH and Ca(OH)2 is formed for CaII:FeIII molar ratios higher than 2:1. Vibrational spectroscopies (Raman and IR) were used successfully to understand the interaction between the cationic and anionic sheets. The Raman bands positions at lower frequencies (150-600 cm-1) are intimately correlated to the nature of the divalent and trivalent ions but also to the nature of the anions. Indeed, a shift of ˜9 cm-1 is observed for the Raman double bands situated in the 300-400 cm-1 region when comparing Raman spectra of CaFe-LDH containing either nitrate or chloride ions. Two types of nitrate environments are observed namely free (non-hydrogen bonded) nitrate and nitrate hydrogen bonded to the interlayer water or to the 'brucite-like' hydroxyl surface. Multiple types of water structure are observed and would result from different hydrogen bond structures. Water bending modes are identified at 1645 cm-1 greater than the one observed for LDH intercalated with chloride anions (1618 cm-1), indicating that the water is strongly hydrogen bonded to the nitrate anions.

  17. Epigallocatechin Gallate/Layered Double Hydroxide Nanohybrids: Preparation, Characterization, and In Vitro Anti-Tumor Study

    PubMed Central

    Shafiei, Seyedeh Sara; Solati-Hashjin, Mehran; Samadikuchaksaraei, Ali; Kalantarinejad, Reza; Asadi-Eydivand, Mitra; Abu Osman, Noor Azuan

    2015-01-01

    In recent years, nanotechnology in merging with biotechnology has been employed in the area of cancer management to overcome the challenges of chemopreventive strategies in order to gain promising results. Since most biological processes occur in nano scale, nanoparticles can act as carriers of certain drugs or agents to deliver it to specific cells or targets. In this study, we intercalated Epigallocatechin-3-Gallate (EGCG), the most abundant polyphenol in green tea, into Ca/Al-NO3 Layered double hydroxide (LDH) nanoparticles, and evaluated its efficacy compared to EGCG alone on PC3 cell line. The EGCG loaded LDH nanohybrids were characterized by X-ray diffraction, Fourier transform infrared spectroscopy, transmission electron microscopy (TEM) and nanosizer analyses. The anticancer activity of the EGCG-loaded LDH was investigated in prostate cancer cell line (PC3) while the release behavior of EGCG from LDH was observed at pH 7.45 and 4.25. Besides enhancing of apoptotic activity of EGCG, the results showed that intercalation of EGCG into LDH can improve the anti- tumor activity of EGCG over 5-fold dose advantages in in-vitro system. Subsequently, the in-vitro release data showed that EGCG-loaded LDH had longer release duration compared to physical mixture, and the mechanism of diffusion through the particle was rate-limiting step. Acidic attack was responsible for faster release of EGCG molecules from LDH at pH of 4.25 compared to pH of 7.4. The results showed that Ca/Al-LDH nanoparticles could be considered as an effective inorganic host matrix for the delivery of EGCG to PC3 cells with controlled release properties. PMID:26317853

  18. Energy and structure of bonds in the interaction of organic anions with layered double hydroxide nanosheets: A molecular dynamics study

    NASA Astrophysics Data System (ADS)

    Tsukanov, A. A.; Psakhie, S. G.

    2016-01-01

    The application of hybrid and hierarchical nanomaterials based on layered hydroxides and oxyhydroxides of metals is a swiftly progressing field in biomedicine. Layered double hydroxides (LDH) possess a large specific surface area, significant surface electric charge and biocompatibility. Their physical and structural properties enable them to adsorb various kinds of anionic species and to transport them into cells. However, possible side effects resulting from the interaction of LDH with anions of the intercellular and intracellular medium need to be considered, since such interaction can potentially disrupt ion transport, signaling processes, apoptosis, nutrition and proliferation of living cells. In the present paper molecular dynamics is used to determine the energies of interaction of organic anions (aspartic acid, glutamic acid and bicarbonate) with a fragment of layered double hydroxide Mg/Al-LDH. The average number of hydrogen bonds between the anions and the hydroxide surface and characteristic binding configurations are determined. Possible effects of LDH on the cell resulting from binding of protein fragments and replacement of native intracellular anions with delivered anions are considered.

  19. Energy and structure of bonds in the interaction of organic anions with layered double hydroxide nanosheets: A molecular dynamics study.

    PubMed

    Tsukanov, A A; Psakhie, S G

    2016-01-01

    The application of hybrid and hierarchical nanomaterials based on layered hydroxides and oxyhydroxides of metals is a swiftly progressing field in biomedicine. Layered double hydroxides (LDH) possess a large specific surface area, significant surface electric charge and biocompatibility. Their physical and structural properties enable them to adsorb various kinds of anionic species and to transport them into cells. However, possible side effects resulting from the interaction of LDH with anions of the intercellular and intracellular medium need to be considered, since such interaction can potentially disrupt ion transport, signaling processes, apoptosis, nutrition and proliferation of living cells. In the present paper molecular dynamics is used to determine the energies of interaction of organic anions (aspartic acid, glutamic acid and bicarbonate) with a fragment of layered double hydroxide Mg/Al-LDH. The average number of hydrogen bonds between the anions and the hydroxide surface and characteristic binding configurations are determined. Possible effects of LDH on the cell resulting from binding of protein fragments and replacement of native intracellular anions with delivered anions are considered. PMID:26817816

  20. Energy and structure of bonds in the interaction of organic anions with layered double hydroxide nanosheets: A molecular dynamics study

    PubMed Central

    Tsukanov, A.A.; Psakhie, S.G.

    2016-01-01

    The application of hybrid and hierarchical nanomaterials based on layered hydroxides and oxyhydroxides of metals is a swiftly progressing field in biomedicine. Layered double hydroxides (LDH) possess a large specific surface area, significant surface electric charge and biocompatibility. Their physical and structural properties enable them to adsorb various kinds of anionic species and to transport them into cells. However, possible side effects resulting from the interaction of LDH with anions of the intercellular and intracellular medium need to be considered, since such interaction can potentially disrupt ion transport, signaling processes, apoptosis, nutrition and proliferation of living cells. In the present paper molecular dynamics is used to determine the energies of interaction of organic anions (aspartic acid, glutamic acid and bicarbonate) with a fragment of layered double hydroxide Mg/Al-LDH. The average number of hydrogen bonds between the anions and the hydroxide surface and characteristic binding configurations are determined. Possible effects of LDH on the cell resulting from binding of protein fragments and replacement of native intracellular anions with delivered anions are considered. PMID:26817816

  1. Layered double hydroxide as an efficient drug reservoir for folate derivatives.

    PubMed

    Choy, Jin-Ho; Jung, Ji-Sun; Oh, Jae-Min; Park, Man; Jeong, Jinyoung; Kang, Young-Koo; Han, Ok-Jin

    2004-07-01

    Folic acid derivatives such as folinic acid and methotrexate (MTX) have been successfully hybridized with layered double hydroxide (LDH) by ion-exchange reaction. The X-ray diffraction patterns and spectroscopic analyses indicate that these molecules intercalated into the hydroxide interlayer space are stabilized in the tilted longitudinal monolayer mode by electrostatic interaction. No significant changes in their structural and functional properties are found in the hybrids. The cellular uptake test of MTX-LDH hybrid is carried out in the fibroblast (human tendon) and SaOS-2 cell line (Osteosarcoma, human) by in vitro MTT (3-(4,5-dimethylthiazol-2-yl) 2,5-diphenyl tetrazolium bromide) assay. The initial proliferation of SaOS-2 cell is more strongly suppressed by treatment with MTX-LDH hybrid than with MTX alone. This study clearly shows that LDH not only plays a role as a biocompatible-delivery matrix for drugs but also facilitates a significant increase in the delivery efficiency. PMID:14967539

  2. MgAl- Layered Double Hydroxide Nanoparticles for controlled release of Salicylate.

    PubMed

    Mondal, Soumini; Dasgupta, Sudip; Maji, Kanchan

    2016-11-01

    Layered double hydroxides (LDHs), have been known for many decades as catalyst and ceramic precursors, traps for anionic pollutants, and additives for polymers. Recently, their successful synthesis on the nanometer scale opened up a whole new field for their application in nanomedicine. Here we report the efficacy of Mg1-xAlx (NO3)x (OH)2 LDH nanoparticles as a carrier and for controlled release of one of the non-steroidal anti-inflammatory drugs (NSAID), sodium salicylate. Mg1-xAlx (NO3)x (OH)2.nH2O nanoparticles were synthesized using co-precipitation method from an aqueous solution of Mg(NO3)2.6H2O and Al(NO3)3.9H2O. Salicylate was intercalated in the interlayer space of Mg-Al LDH after suspending nanoparticles in 0.0025(M) HNO3 and 0.75 (M) NaNO3 solution and using anion exchange method under N2 atmosphere. The shift in the basal planes like (003) and (006) to lower 2θ value in the XRD plot of intercalated sample confirmed the increase in basal spacing in LDH because of intercalation of salicylate into the interlayer space of LDH. FTIR spectroscopy of SA-LDH nano hybrid revealed a red shift in the frequency band of carboxylate group in salicylate indicating an electrostatic interaction between cationic LDH sheet and anionic drug. Differential thermal analysis of LDH-SA nanohybrid indicated higher thermal stability of salicylate in the intercalated form into LDH as compared to its free state. DLS studies showed a particle size distribution between 30-60 nm for pristine LDH whereas salicylate intercalated LDH exhibited a particle size distribution between 40-80nm which is ideal for its efficacy as a superior carrier for drugs and biomolecules. The cumulative release kinetic of salicylate from MgAl-LDH-SA hybrids in phosphate buffer saline (PBS) at pH7.4 showed a sustained release of salicylate up to 72h that closely resembled first order release kinetics through a combination of drug diffusion and dissolution of LDH under physiological conditions. Also the

  3. Efficient delivery of siRNA to cortical neurons using layered double hydroxide nanoparticles.

    PubMed

    Wong, Yunyi; Markham, Kathryn; Xu, Zhi Ping; Chen, Min; Max Lu, Gao Qing; Bartlett, Perry F; Cooper, Helen M

    2010-11-01

    Small interfering RNAs (siRNAs) are capable of targeting and destroying specific mRNAs, making them particularly suited to the treatment of neurodegenerative conditions such as Huntington's Disease where the production of abnormal proteins results in a gain-of-function phenotype. Although a variety of nanoparticle formulations are currently under development as siRNA delivery systems, application of these technologies has been limited by their high cytotoxicity, low drug loading capacity and release, and inability to penetrate cell membranes. Layered double hydroxide (LDH) nanoparticles are now emerging as a potential new drug delivery system as they exhibit low cytotoxicity and are highly biocompatible. Here we present the first study investigating LDH delivery of siRNAs to primary cultured neurons. We show that internalization by neurons is rapid, dose-dependent and saturable, and markedly more efficient than in other cell types. We demonstrate that siRNA-LDH complexes are internalized by clathrin-dependent endocytosis at the cell body and in neurites, with subsequent retrograde transport to the cell body followed by efficient release into the cytoplasm. Finally we show that LDH mediated siRNA delivery effectively silences neuronal gene expression. This study therefore confirms the potential of LDH nanoparticles as a drug delivery system for patients suffering from neurodegenerative disease. PMID:20709387

  4. Polarized immune responses modulated by layered double hydroxides nanoparticle conjugated with CpG.

    PubMed

    Yan, Shiyu; Rolfe, Barbara E; Zhang, Bing; Mohammed, Yousuf H; Gu, Wenyi; Xu, Zhi P

    2014-11-01

    Modulation of the immune response is an important step in the induction of protective humoral and cellular immunity against pathogens. In this study, we investigated the possibility of using a nanomaterial conjugated with the toll-like receptor (TLR) ligand CpG to modulate the immune response towards the preferred polarity. MgAl-layered double hydroxide (LDH) nanomaterial has a very similar chemical composition to Alum, an FDA approved adjuvant for human vaccination. We used a model antigen, ovalbumin (OVA) to demonstrate that MgAl-LDH had comparable adjuvant activity to Alum, but much weaker inflammation. Conjugation of TLR9 ligand CpG to LDH nanoparticles significantly enhanced the antibody response and promoted a switch from Th2 toward Th1 response, demonstrated by a change in the IgG2a:IgG1 ratio. Moreover, immunization of mice with CpG-OVA-conjugated LDH before challenge with OVA-expressing B16/F10 tumor cells retarded tumor growth. Together, these data indicate that LDH nanomaterial can be used as an immune adjuvant to promote Th1 or Th2 dominant immune responses suitable for vaccination purposes. PMID:25145853

  5. Layered double hydroxides as supports for the slow release of acid herbicides.

    PubMed

    Cardoso, Lucelena P; Celis, Rafael; Cornejo, Juan; Valim, João B

    2006-08-01

    A Mg/Al layered double hydroxide (LDH) was intercalated with the anionic herbicides 2,4-D, MCPA, and picloram by using three different methodologies: (i) direct synthesis (DS), (ii) regeneration (RE), and (iii) ion exchange (IE). The resulting complexes were characterized and assayed by batch release and column leaching tests, aiming at the controlled release of these herbicides. All the tested LDH-herbicide complexes displayed similar slow herbicide release properties in water, although the IE method seemed to result in complexes with a greater fraction of herbicide in a readily available form. Apparently, the LDH-herbicide complexes released most of the active ingredient present in the complexes at the end of the batch release experiment. This was attributed to the replacement of the intercalated herbicide by carbonate and hydroxyl anions from the aqueous solution. Compared to the free herbicides, the application of the three LDH-herbicide complexes (RE) to soil columns resulted in reduction in the maximum herbicide concentration in leachates and led to the retardation of herbicide leaching through the soil. All LDH-herbicide complexes presented an herbicidal efficacy similar to that of the free (technical) herbicides. Our results indicated the potential applicability of LDHs as supports for the preparation of slow release formulations of acid herbicides such as 2,4-D, MCPA, or picloram. PMID:16881703

  6. Starch Biocatalyst Based on α-Amylase-Mg/Al-Layered Double Hydroxide Nanohybrids.

    PubMed

    Bruna, Felipe; Pereira, Marita G; Polizeli, Maria de Lourdes T M; Valim, João B

    2015-08-26

    The design of new biocatalysts through the immobilization of enzymes, improving their stability and reuse, plays a major role in the development of sustainable methodologies toward the so-called green chemistry. In this work, α-amylase (AAM) biocatalyst based on Mg3Al-layered double-hydroxide (LDH) matrix was successfully developed with the adsorption method. The adsorption process was studied and optimized as a function of time and enzyme concentration. The biocatalyst was characterized, and the mechanism of interaction between AAM and LDH, as well as the immobilization effects on the catalytic activity, was elucidated. The adsorption process was fast and irreversible, thus yielding a stable biohybrid material. The immobilized AAM partially retained its enzymatic activity, and the biocatalyst rapidly hydrolyzed starch in an aqueous solution with enhanced efficiency at intermediate loading values of ca. 50 mg/g of AAM/LDH. Multiple attachments through electrostatic interactions affected the conformation of the immobilized enzyme on the LDH surface. The biocatalyst was successfully stored in its dry form, retaining 100% of its catalytic activity. The results reveal the potential usefulness of a LDH compound as a support of α-amylase for the hydrolysis of starch that may be applied in industrial and pharmaceutical processes as a simple, environmentally friendly, and low-cost biocatalyst. PMID:26259168

  7. Synthesis and characterization of 10-hydroxycamptothecin - sebacate - layered double hydroxide nanocomposites

    NASA Astrophysics Data System (ADS)

    Pang, Xiujiang; Ma, Xiuming; Li, Dongxiang; Hou, Wanguo

    2013-02-01

    10-Hydroxycamptothecin (HCPT) as a hydrophobic anticancer drug brings many challenges in the clinical applications due to its poor water solubility and the presence of a chemically unstable lactone ring. In this work, the nanocomposites of HCPT intercalated layered double hydroxide (LDH) were prepared by a secondary intercalation method, and the encapsulated HCPT could keep the biologically active lactone form. A Zn-Al-NO3 LDH was pillared with sebacate anions by a co-precipitation method in an aqueous medium, and then HCPT was intercalated into the LDH's gallery via hydrophobic interaction in an ethanol medium. The parallel alkyl chains of perpendicularly arranged sebacate anions in the LDH gallery provide a hydrophobic space for the drug intercalation. The in vitro release kinetics of HCPT from the nanocomposites could be fitted with the pseudo-second-order kinetic model, and the diffusion of HCPT through the LDH particles played an important role in controlling the drug release. The nanocomposites can be considered as a potential drug delivery system.

  8. Antibacterial carboxymethyl cellulose/Ag nanocomposite hydrogels cross-linked with layered double hydroxides.

    PubMed

    Yadollahi, Mehdi; Namazi, Hassan; Aghazadeh, Mohammad

    2015-08-01

    This paper deals with the preparation of antibacterial nanocomposite hydrogels through the combination of carboxy methyl cellulose (CMC), layered double hydroxides (LDH), and silver nanoparticles (AgNPs). CMC-LDH hydrogels were prepared by intercalating CMC into different LDHs. Then, Ag/CMC-LDH nanocomposite hydrogels were prepared through in situ formation of AgNPs within the CMC-LDHs. XRD analysis confirmed the intercalating CMC into the LDH sheets and formation of intercalated structures, as well as formation of AgNPs within the CMC-LDHs. SEM and TEM micrographs indicated well distribution of AgNPs within the Ag/CMC-LDHs. The prepared hydrogels showed a pH sensitive swelling behavior. The Ag/CMC-LDH nanocomposite hydrogels have rather higher swelling in different aqueous solutions in comparison with CMC-LDHs. The antibacterial activity of CMC-LDHs increased considerably after formation of AgNPs and was stable for more than one month. PMID:25964179

  9. Anticancer Drug-Incorporated Layered Double Hydroxide Nanohybrids and Their Enhanced Anticancer Therapeutic Efficacy in Combination Cancer Treatment

    PubMed Central

    Lee, Gyeong Jin; Kang, Joo-Hee

    2014-01-01

    Objective. Layered double hydroxide (LDH) nanoparticles have been studied as cellular delivery carriers for anionic anticancer agents. As MTX and 5-FU are clinically utilized anticancer drugs in combination therapy, we aimed to enhance the therapeutic performance with the help of LDH nanoparticles. Method. Anticancer drugs, MTX and 5-FU, and their combination, were incorporated into LDH by reconstruction method. Simply, LDHs were thermally pretreated at 400°C, and then reacted with drug solution to simultaneously form drug-incorporated LDH. Thus prepared MTX/LDH (ML), 5-FU/LDH (FL), and (MTX + 5-FU)/LDH (MFL) nanohybrids were characterized by X-ray diffractometer, scanning electron microscopy, infrared spectroscopy, thermal analysis, zeta potential measurement, dynamic light scattering, and so forth. The nanohybrids were administrated to the human cervical adenocarcinoma, HeLa cells, in concentration-dependent manner, comparing with drug itself to verify the enhanced therapeutic efficacy. Conclusion. All the nanohybrids successfully accommodated intended drug molecules in their house-of-card-like structures during reconstruction reaction. It was found that the anticancer efficacy of MFL nanohybrid was higher than other nanohybrids, free drugs, or their mixtures, which means the multidrug-incorporated LDH nanohybrids could be potential drug delivery carriers for efficient cancer treatment via combination therapy. PMID:24860812

  10. Direct observation of grafting interlayer phosphate in Mg/Al layered double hydroxides

    SciTech Connect

    Shimamura, Akihiro; Kanezaki, Eiji; Jones, Mark I.; Metson, James B.

    2012-02-15

    The grafting of interlayer phosphate in synthetic Mg/Al layered double hydroxides with interlayer hydrogen phosphate (LDH-HPO{sub 4}) has been studied by XRD, TG/DTA, FT-IR, XPS and XANES. The basal spacing of crystalline LDH-HPO{sub 4} decreases in two stages with increasing temperature, from 1.06 nm to 0.82 nm at 333 K in the first transition, and to 0.722 nm at 453 K in the second. The first stage occurs due to the loss of interlayer water and rearrangement of the interlayer HPO{sub 4}{sup 2-}. In the second transition, the interlayer phosphate is grafted to the layer by the formation of direct bonding to metal cations in the layer, accompanied by a change in polytype of the crystalline structure. The grafted phosphate becomes immobilized and cannot be removed by anion-exchange with 1-octanesulfonate. The LDH is amorphous at 743 K but decomposes to Mg{sub 3}(PO{sub 4}){sub 2}, AlPO{sub 4}, MgO and MgAl{sub 2}O{sub 4} after heated to 1273 K. - Graphical abstract: The cross section of the synthetic Mg, Al layered double hydroxides in Phase 1, with interlayer hydrogen phosphate Phase 2, and with grafted phosphate, Phase 3. Highlights: Black-Right-Pointing-Pointer The grafting of hydrogen phosphate intercalated Mg/Al-LDH has been studied. Black-Right-Pointing-Pointer The basal spacing of crystalline LDH-HPO{sub 4} decreases in two stages with increasing temperature. Black-Right-Pointing-Pointer The first decrease is due to loss of interlayer water, the second is attributed to phosphate grafting. Black-Right-Pointing-Pointer The grafted interlayer phosphate becomes immobilized and cannot be removed by anion-exchange.

  11. Double layered hydroxides as potential anti-cancer drug delivery agents.

    PubMed

    Riaz, Ufana; Ashraf, S M

    2013-04-01

    The emergence of nanotechnology has changed the scenario of the medical world by revolutionizing the diagnosis, monitoring and treatment of cancer. This nanotechnology has been proved miraculous in detecting cancer cells, delivering chemotherapeutic agents and monitoring treatment from non-specific to highly targeted killing of tumor cells. In the past few decades, a number of inorganic materials have been investigated such as calcium phosphate, gold, carbon materials, silicon oxide, iron oxide, and layered double hydroxide (LDH) for examining their efficacy in targeting drug delivery. The reason behind the selection of these inorganic materials was their versatile and unique features efficient in drug delivery, such as wide availability, rich surface functionality, good biocompatibility, potential for target delivery, and controlled release of the drug from these inorganic nanomaterials. Although, the drug-LDH hybrids are found to be quite instrumental because of their application as advanced anti-cancer drug delivery systems, there has not been much research on them. This mini review is set to highlight the advancement made in the use of layered double hydroxides (LDHs) as anti-cancer drug delivery agents. Along with the advantages of LDHs as anti-cancer drug delivery agents, the process of interaction of some of the common anti-cancer drugs with LDH has also been discussed. PMID:23170959

  12. A facile method for the construction of covalently cross-linked layered double hydroxides layer-by-layer films: Enhanced stability and delayed release of guests

    NASA Astrophysics Data System (ADS)

    Li, Yulong; An, Qi; Hu, Yingmo; Luan, Xinglong; Zhang, Qian; Zhang, Tianhang; Zhang, Yihe

    2015-07-01

    Stable composite films that contain layered double hydroxide (LDH) are appealing materials but are also difficult to prepare. We report here a facile strategy for the fabrication of covalently cross-linked layer-by-layer multilayers that incorporate LDH. The films were first prepared using the traditional LbL method based on non-covalent interactions, followed by infiltration of a photoactive small molecule DAS. UV light was then used to cross-link the multilayers. The stability of the cross-linked film was remarkably enhanced. Furthermore, the release profile of incorporated molecules from layered double hydroxide was significantly delayed.

  13. Ultrafast switching of an electrochromic device based on layered double hydroxide/Prussian blue multilayered films

    NASA Astrophysics Data System (ADS)

    Liu, Xiaoxi; Zhou, Awu; Dou, Yibo; Pan, Ting; Shao, Mingfei; Han, Jingbin; Wei, Min

    2015-10-01

    Electrochromic materials are the most important and essential components in an electrochromic device. Herein, we fabricated high-performance electrochromic films based on exfoliated layered double hydroxide (LDH) nanosheets and Prussian blue (PB) nanoparticles via the layer-by-layer assembly technique. X-ray diffraction and UV-vis absorption spectroscopy indicate a periodic layered structure with uniform and regular growth of (LDH/PB)n ultrathin films (UTFs). The resulting (LDH/PB)n UTF electrodes exhibit electrochromic behavior arising from the reversible K+ ion migration into/out of the PB lattice, which induces a change in the optical properties of the UTFs. Furthermore, an electrochromic device (ECD) based on the (LDH/PB)n-ITO/0.1 M KCl electrolyte/ITO sandwich structure displays superior response properties (0.91/1.21 s for coloration/bleaching), a comparable coloration efficiency (68 cm2 C-1) and satisfactory optical contrast (45% at 700 nm), in comparison with other inorganic material-based ECDs reported previously. Therefore, this work presents a facile and cost-effective strategy to immobilize electrochemically active nanoparticles in a 2D inorganic matrix for potential application in displays, smart windows and optoelectronic devices.Electrochromic materials are the most important and essential components in an electrochromic device. Herein, we fabricated high-performance electrochromic films based on exfoliated layered double hydroxide (LDH) nanosheets and Prussian blue (PB) nanoparticles via the layer-by-layer assembly technique. X-ray diffraction and UV-vis absorption spectroscopy indicate a periodic layered structure with uniform and regular growth of (LDH/PB)n ultrathin films (UTFs). The resulting (LDH/PB)n UTF electrodes exhibit electrochromic behavior arising from the reversible K+ ion migration into/out of the PB lattice, which induces a change in the optical properties of the UTFs. Furthermore, an electrochromic device (ECD) based on the (LDH

  14. Antimycobacterial, antimicrobial, and biocompatibility properties of para-aminosalicylic acid with zinc layered hydroxide and Zn/Al layered double hydroxide nanocomposites

    PubMed Central

    Saifullah, Bullo; El Zowalaty, Mohamed E; Arulselvan, Palanisamy; Fakurazi, Sharida; Webster, Thomas J; Geilich, Benjamin M; Hussein, Mohd Zobir

    2014-01-01

    The treatment of tuberculosis by chemotherapy is complicated due to multiple drug prescriptions, long treatment duration, and adverse side effects. We report here for the first time an in vitro therapeutic effect of nanocomposites based on para-aminosalicylic acid with zinc layered hydroxide (PAS-ZLH) and zinc-aluminum layered double hydroxides (PAS-Zn/Al LDH), against mycobacteria, Gram-positive bacteria, and Gram-negative bacteria. The nanocomposites demonstrated good antimycobacterial activity and were found to be effective in killing Gram-positive and Gram-negative bacteria. A biocompatibility study revealed good biocompatibility of the PAS-ZLH nanocomposites against normal human MRC-5 lung cells. The para-aminosalicylic acid loading was quantified with high-performance liquid chromatography analysis. In summary, the present preliminary in vitro studies are highly encouraging for further in vivo studies of PAS-ZLH and PAS-Zn/Al LDH nanocomposites to treat tuberculosis. PMID:25114509

  15. Prolate spheroidal hematite particles equatorially belt with drug-carrying layered double hydroxide disks: Ring Nebula-like nanocomposites

    NASA Astrophysics Data System (ADS)

    Nedim Ay, Ahmet; Konuk, Deniz; Zümreoglu-Karan, Birgul

    2011-12-01

    A new nanocomposite architecture is reported which combines prolate spheroidal hematite nanoparticles with drug-carrying layered double hydroxide [LDH] disks in a single structure. Spindle-shaped hematite nanoparticles with average length of 225 nm and width of 75 nm were obtained by thermal decomposition of hydrothermally synthesized hematite. The particles were first coated with Mg-Al-NO3-LDH shell and then subjected to anion exchange with salicylate ions. The resulting bio-nanohybrid displayed a close structural resemblance to that of the Ring Nebula. Scanning electron microscope and transmission electron microscopy images showed that the LDH disks are stacked around the equatorial part of the ellipsoid extending along the main axis. This geometry possesses great structural tunability as the composition of the LDH and the nature of the interlayer region can be tailored and lead to novel applications in areas ranging from functional materials to medicine by encapsulating various guest molecules.

  16. In vitro controlled release of vitamin C from Ca/Al layered double hydroxide drug delivery system.

    PubMed

    Gao, Xiaorui; Chen, Le; Xie, Juan; Yin, Yaobing; Chang, Tao; Duan, Yancong; Jiang, Nan

    2014-06-01

    A new drug delivery system for vitamin C (VC), Ca/Al layered double hydroxide (LDH), is demonstrated in this work. VC anions were intercalated successfully in the Ca/Al LDH gallery by a coprecipitation method. The interlayer space of 9.8Å suggests that VC anions are vertical to the LDH layers in the form of interdigitated bilayer. The loading of VC in LDH is 36.4wt.%. The thermal stability of VC is significantly enhanced after intercalation. In vitro VC release results show that the release time of VC in a phosphate buffer at pH7.4 was significantly extended, and the maximal percentage of VC released is 80% of the total. The Avrami-Erofe'ev equation most satisfactorily explains the release kinetics of VC, which is that the release of VC is mainly dominated by the ion-exchange reaction. PMID:24863197

  17. Rapid exchange between atmospheric CO2 and carbonate anion intercalated within magnesium rich layered double hydroxide.

    PubMed

    Sahoo, Pathik; Ishihara, Shinsuke; Yamada, Kazuhiko; Deguchi, Kenzo; Ohki, Shinobu; Tansho, Masataka; Shimizu, Tadashi; Eisaku, Nii; Sasai, Ryo; Labuta, Jan; Ishikawa, Daisuke; Hill, Jonathan P; Ariga, Katsuhiko; Bastakoti, Bishnu Prasad; Yamauchi, Yusuke; Iyi, Nobuo

    2014-10-22

    The carbon cycle, by which carbon atoms circulate between atmosphere, oceans, lithosphere, and the biosphere of Earth, is a current hot research topic. The carbon cycle occurring in the lithosphere (e.g., sedimentary carbonates) is based on weathering and metamorphic events so that its processes are considered to occur on the geological time scale (i.e., over millions of years). In contrast, we have recently reported that carbonate anions intercalated within a hydrotalcite (Mg0.75Al0.25(OH)2(CO3)0.125·yH2O), a class of a layered double hydroxide (LDH), are dynamically exchanging on time scale of hours with atmospheric CO2 under ambient conditions. (Ishihara et al., J. Am. Chem. Soc. 2013, 135, 18040-18043). The use of (13)C-labeling enabled monitoring by infrared spectroscopy of the dynamic exchange between the initially intercalated (13)C-labeled carbonate anions and carbonate anions derived from atmospheric CO2. In this article, we report the significant influence of Mg/Al ratio of LDH on the carbonate anion exchange dynamics. Of three LDHs of various Mg/Al ratios of 2, 3, or 4, magnesium-rich LDH (i.e., Mg/Al ratio = 4) underwent extremely rapid exchange of carbonate anions, and most of the initially intercalated carbonate anions were replaced with carbonate anions derived from atmospheric CO2 within 30 min. Detailed investigations by using infrared spectroscopy, scanning electron microscopy, powder X-ray diffraction, elemental analysis, adsorption, thermogravimetric analysis, and solid-state NMR revealed that magnesium rich LDH has chemical and structural features that promote the exchange of carbonate anions. Our results indicate that the unique interactions between LDH and CO2 can be optimized simply by varying the chemical composition of LDH, implying that LDH is a promising material for CO2 storage and/or separation. PMID:25275963

  18. Recyclable Mg-Al layered double hydroxides for fluoride removal: Kinetic and equilibrium studies.

    PubMed

    Kameda, Tomohito; Oba, Jumpei; Yoshioka, Toshiaki

    2015-12-30

    Mg-Al layered double hydroxides (LDHs) intercalated with NO3(-) (NO3 · Mg-Al LDH) and Cl(-) (Cl · Mg-Al LDH) were found to adsorb fluoride from aqueous solutions. Fluoride is removed by anion exchange in solution with NO3(-) and Cl(-) intercalated in the LDH interlayer. In both cases, the residual F concentration is lower than the effluent standards for F in Japan (8 mg/L). The rate-determining step in the removal of F using NO3 · Mg-Al and Cl · Mg-Al LDH is chemical adsorption involving F(-) anion exchange with intercalated NO3(-) and Cl(-) ions. The removal of F is described by pseudo-second-order reaction kinetics, with Langmuir-type adsorption. The values obtained for the maximum adsorption and the equilibrium adsorption constant are respectively 3.3 mmol g(-1) and 2.8 with NO3 · Mg-Al LDH, and 3.2 mmol g(-1) and 1.5 with Cl · Mg-Al LDH. The F in the F · Mg-Al LDH produced in these reactions was found to exchange with NO3(-) and Cl(-) ions in solution. The regenerated NO3 · Mg-Al and Cl · Mg-Al LDHs thus obtained can be used once more to capture aqueous F. This suggests that NO3 · Mg-Al and Cl · Mg-Al LDHs can be recycled and used repeatedly for F removal. PMID:26223022

  19. Phosphate-intercalated Ca-Fe-layered double hydroxides: Crystal structure, bonding character, and release kinetics of phosphate

    NASA Astrophysics Data System (ADS)

    Woo, Myong A.; Woo Kim, Tae; Paek, Mi-Jeong; Ha, Hyung-Wook; Choy, Jin-Ho; Hwang, Seong-Ju

    2011-01-01

    The nitrate-form of Ca-Fe-layered double hydroxide (Ca-Fe-LDH) was synthesized via co-precipitation method, and its phosphate-intercalates were prepared by ion-exchange reaction. According to X-ray diffraction analysis, the Ca-Fe-LDH-NO 3- compound and its H 2PO 4--intercalate showed hexagonal layered structures, whereas the ion-exchange reaction with HPO 42- caused a frustration of the layer ordering of LDH. Fe K-edge X-ray absorption spectroscopy clearly demonstrated that the Ca-Fe-LDH lattice with trivalent iron ions was well-maintained after the ion-exchange with HPO 42- and H 2PO 4-. Under acidic conditions, phosphate ions were slowly released from the Ca-Fe-LDH lattice and the simultaneous release of hydroxide caused the neutralization of acidic media. Fitting analysis based on kinetic models indicated a heterogeneous diffusion process of phosphates and a distinct dependence of release rate on the charge of phosphates. This study strongly suggested that Ca-Fe-LDH is applicable as bifunctional vector for slow release of phosphate fertilizer and for the neutralization of acid soil.

  20. Lubrication performance and mechanisms of Mg/Al-, Zn/Al-, and Zn/Mg/Al-layered double hydroxide nanoparticles as lubricant additives

    NASA Astrophysics Data System (ADS)

    Li, Shuo; Bhushan, Bharat

    2016-08-01

    Solid lubricant particles are commonly used as oil additives for low friction and wear. Mg/Al-, Zn/Al-, and Zn/Mg/Al-layered double hydroxides (LDH) were synthesized by coprecipitation method. The benefits of LDH nanoparticles are that they can be synthesized using chemical methods where size and shape can be controlled, and can be modified organically to allow dispersal in fluids. The LDH nanoparticles were characterized by X-ray diffraction, scanning electron microscope, thermogravimetry, and differential scanning calorimetry. A pin-on-disk friction and wear tester was used for evaluating the friction and wear properties of LDH nanoparticles as lubricant additives. LDH nanoparticles have friction-reducing and anti-wear properties compared to oil without LDHs. Mg/Al-LDH has the best lubrication, possibly due to better thermal stability in severe conditions.

  1. Binder-free Co3O4@NiCoAl-layered double hydroxide core-shell hybrid architectural nanowire arrays with enhanced electrochemical performance

    NASA Astrophysics Data System (ADS)

    Li, Xuan; Yang, Zhengchun; Qi, Wen; Li, Yutao; Wu, Ying; Zhou, Shaoxiong; Huang, Shengming; Wei, Jun; Li, Huijun; Yao, Pei

    2016-02-01

    Herein, binder-free Co3O4@NiCoAl-layered double hydroxide (Co3O4@LDH) core-shell hybrid architectural nanowire arrays were prepared via a two-step hydrothermal synthesis route. LDH nanosheets possessing a large electroactive surface area uniformly dispersed on the surface of Co3O4 nanowires were successfully fabricated allowing for fast electron transport that enhances the electrochemical performance of LDH nanosheets. Co3O4@LDH nanowire arrays of 2 to 1.5 molar ratio (Co3O4:LDH) exhibit high specific capacitance (1104 F g-1 at 1 A g-1), adequate rate capability and cycling stability (87.3% after 5000 cycles), attributed to the synergistic effect between the robust Co3O4 nanowire arrays and LDH nanosheets.

  2. Detection of copper ions from aqueous solutions using layered double hydroxides thin films deposited by PLD

    NASA Astrophysics Data System (ADS)

    Vlad, A.; Birjega, R.; Matei, A.; Luculescu, C.; Nedelcea, A.; Dinescu, M.; Zavoianu, R.; Pavel, O. D.

    2015-10-01

    Layered double hydroxides (LDHs) thin films with Mg-Al were deposited using pulsed laser deposition (PLD) technique. We studied the ability of our films to detect copper ions in aqueous solutions. Copper is known to be a common pollutant in water, originating from urban and industrial waste. Clay minerals, including layered double hydroxides (LDHs), can reduce the toxicity of such wastes by adsorbing copper. We report on the uptake of copper ions from aqueous solution on LDH thin films obtained via PLD. The obtained thin films were characterized using X-ray Diffraction, Atomic Force Microscopy, and Scanning Electron Microscopy with Energy Dispersive X-ray analysis. The results in this study indicate that LDHs thin films obtained by PLD have potential as an efficient adsorbent for removing copper from aqueous solution.

  3. Facile one-step synthesis of nanocomposite based on carbon nanotubes and Nickel-Aluminum layered double hydroxides with high cycling stability for supercapacitors.

    PubMed

    Bai, Caihui; Sun, Shiguo; Xu, Yongqian; Yu, Ruijin; Li, Hongjuan

    2016-10-15

    Nickel-Aluminum Layered Double Hydroxide (NiAl-LDH) and nanocomposite of Carbon Nanotubes (CNTs) and NiAl-LDH (CNTs/NiAl-LDH) were prepared by using a facile one-step homogeneous precipitation approach. The morphology, structure and electrochemical properties of the as-prepared CNTs/NiAl-LDH nanocomposite were then systematically studied. According to the galvanostatic charge-discharge curves, the CNTs/NiAl-LDH nanocomposite exhibited a high specific capacitance of 694Fg(-1) at the 1Ag(-1). Furthermore, the specific capacitance of the CNTs/NiAl-LDH nanocomposite still retained 87% when the current density was increased from 1 to 10Ag(-1). These results indicated that the CNTs/NiAl-LDH nanocomposite displayed a higher specific capacitance and rate capability than pure NiAl-LDH. And the participation of CNTs in the NiAl-LDH composite improved the electrochemical properties. Additionally, the capacitance of the CNTs/NiAl-LDH nanocomposite kept at least 92% after 3000cycles at 20Ag(-1), suggesting that the nanocomposite exhibited excellent cycling durability. This strategy provided a facile and effective approach for the synthesis of nanocomposite based on CNTs and NiAl-LDH with enhanced supercapacitor behaviors, which can be potentially applied in energy storage conversion devices. PMID:27405071

  4. Large-scale simulations of layered double hydroxide nanocomposite materials

    NASA Astrophysics Data System (ADS)

    Thyveetil, Mary-Ann

    Layered double hydroxides (LDHs) have the ability to intercalate a multitude of anionic species. Atomistic simulation techniques such as molecular dynamics have provided considerable insight into the behaviour of these materials. We review these techniques and recent algorithmic advances which considerably improve the performance of MD applications. In particular, we discuss how the advent of high performance computing and computational grids has allowed us to explore large scale models with considerable ease. Our simulations have been heavily reliant on computational resources on the UK's NGS (National Grid Service), the US TeraGrid and the Distributed European Infrastructure for Supercomputing Applications (DEISA). In order to utilise computational grids we rely on grid middleware to launch, computationally steer and visualise our simulations. We have integrated the RealityGrid steering library into the Large-scale Atomic/Molecular Massively Parallel Simulator (LAMMPS) 1 . which has enabled us to perform re mote computational steering and visualisation of molecular dynamics simulations on grid infrastruc tures. We also use the Application Hosting Environment (AHE) 2 in order to launch simulations on remote supercomputing resources and we show that data transfer rates between local clusters and super- computing resources can be considerably enhanced by using optically switched networks. We perform large scale molecular dynamics simulations of MgiAl-LDHs intercalated with either chloride ions or a mixture of DNA and chloride ions. The systems exhibit undulatory modes, which are suppressed in smaller scale simulations, caused by the collective thermal motion of atoms in the LDH layers. Thermal undulations provide elastic properties of the system including the bending modulus, Young's moduli and Poisson's ratios. To explore the interaction between LDHs and DNA. we use molecular dynamics techniques to per form simulations of double stranded, linear and plasmid DNA up

  5. Synthesis and selective IR absorption properties of iminodiacetic-acid intercalated MgAl-layered double hydroxide

    SciTech Connect

    Wang Lijing; Xu Xiangyu; Evans, David G.; Duan Xue; Li Dianqing

    2010-05-15

    An MgAl-NO{sub 3}-layered double hydroxide (LDH) precursor has been prepared by a method involving separate nucleation and aging steps (SNAS). Reaction with iminodiacetic acid (IDA) under weakly acidic conditions led to the replacement of the interlayer nitrate anions by iminodiacetic acid anions. The product was characterized by XRD, FT-IR, TG-DTA, ICP, elemental analysis and SEM. The results show that the original interlayer nitrate anions of LDHs precursor were replaced by iminodiacetic acid anions and that the resulting intercalation product MgAl-IDA-LDH has an ordered crystalline structure. MgAl-IDA-LDH was mixed with low density polyethylene (LDPE) using a masterbatch method. LDPE films filled with MgAl-IDA-LDH showed a higher mid to far infrared absorption than films filled with MgAl-CO{sub 3}-LDH in the 7-25 {mu}m range, particularly in the key 9-11 {mu}m range required for application in agricultural plastic films. - Graphical abstract: Intercalation of iminodiacetic acid (IDA) anions in a MgAl-NO{sub 3}-layered double hydroxide host leads to an enhancement of its infrared absorbing ability for application in agricultural plastic films.

  6. Intercalation and controlled release properties of vitamin C intercalated layered double hydroxide

    SciTech Connect

    Gao, Xiaorui; Lei, Lixu; O'Hare, Dermot; Xie, Juan; Gao, Pengran; Chang, Tao

    2013-07-15

    Two drug-inorganic composites involving vitamin C (VC) intercalated in Mg–Al and Mg–Fe layered double hydroxides (LDHs) have been synthesized by the calcination–rehydration (reconstruction) method. Powder X-ray diffraction (XRD), Fourier transform infrared (FTIR), and UV–vis absorption spectroscopy indicate a successful intercalation of VC into the interlayer galleries of the LDH host. Studies of VC release from the LDHs in deionised water and in aqueous CO{sub 3}{sup 2−} solutions imply that Mg{sub 3}Al–VC LDH is a better controlled release system than Mg{sub 3}Fe–VC LDH. Analysis of the release profiles using a number of kinetic models suggests a solution-dependent release mechanism, and a diffusion-controlled deintercalation mechanism in deionised water, but an ion exchange process in CO{sub 3}{sup 2−} solution. - Graphical abstract: Vitamin C anions have been intercalated in the interlayer space of layered double hydroxide and released in CO{sub 3}{sup 2−} solution and deionised water. - Highlights: • Vitamin C intercalated Mg–Al and Mg–Fe layered double hydroxides were prepared. • Release property of vitamin C in aqueous CO{sub 3}{sup 2−} solution is better. • Avrami-Erofe’ev and first-order models provide better fit for release results. • Diffusion-controlled and ion exchange processes occur in deionised water. • An ion exchange process occurs in CO{sub 3}{sup 2−} solution.

  7. A photochromic thin film based on salicylideneaniline derivatives intercalated layered double hydroxide

    NASA Astrophysics Data System (ADS)

    Wang, Xin Rui; Lu, Jun; Yan, Dongpeng; Wei, Min; Evans, David G.; Duan, Xue

    2010-06-01

    Optically transparent thin films with photochromic properties have been fabricated by means of co-intercalation of azomethine-H anions (AMH) and 1-pentanesulfonate (PS) with different molar ratios into the galleries of a ZnAl layered double hydroxide (LDH). The photochromism of AMH occurred in a 2D confined inorganic matrix has been studied by steady state and transient UV-vis spectroscopy. The AMH anion undergoes an excited-state intramolecular proton transfer from the enol tautomer to trans-keto tautomer after UV excitation, and the relaxed back-isomerization to the ground state of enol tautomer was investigated by transient UV-vis spectroscopy.

  8. Layered double hydroxide nanoparticles promote self-renewal of mouse embryonic stem cells through the PI3K signaling pathway

    NASA Astrophysics Data System (ADS)

    Wu, Youjun; Zhu, Rongrong; Zhou, Yang; Zhang, Jun; Wang, Wenrui; Sun, Xiaoyu; Wu, Xianzheng; Cheng, Liming; Zhang, Jing; Wang, Shilong

    2015-06-01

    Embryonic stem cells (ESCs) hold great potential for regenerative medicine due to their two unique characteristics: self-renewal and pluripotency. Several groups of nanoparticles have shown promising applications in directing the stem cell fate. Herein, we investigated the cellular effects of layered double hydroxide nanoparticles (LDH NPs) on mouse ESCs (mESCs) and the associated molecular mechanisms. Mg-Al-LDH NPs with an average diameter of ~100 nm were prepared by hydrothermal methods. To determine the influences of LDH NPs on mESCs, cellular cytotoxicity, self-renewal, differentiation potential, and the possible signaling pathways were explored. Evaluation of cell viability, lactate dehydrogenase release, ROS generation and apoptosis demonstrated the low cytotoxicity of LDH NPs. The alkaline phosphatase activity and the expression of pluripotency genes in mESCs were examined, which indicated that exposure to LDH NPs could support self-renewal and inhibit spontaneous differentiation of mESCs under feeder-free culture conditions. The self-renewal promotion was further proved to be independent of the leukemia inhibitory factor (LIF). Furthermore, cells treated with LDH NPs maintained the potential to differentiate into all three germ layers both in vitro and in vivo through formation of embryoid bodies and teratomas. In addition, we observed that LDH NPs initiated the activation of the PI3K/Akt pathway, while treatment with the PI3K inhibitor LY294002 could block the effects of LDH NPs on mESCs. The results confirmed that the promotion of self-renewal by LDH NPs was associated with activation of the PI3K/Akt signaling pathway. Altogether, our studies identified a new role of LDH NPs in maintaining self-renewal of mouse ES cells which could potentially be applied in stem cell research.Embryonic stem cells (ESCs) hold great potential for regenerative medicine due to their two unique characteristics: self-renewal and pluripotency. Several groups of nanoparticles

  9. Wetting behavior and drag reduction of superhydrophobic layered double hydroxides films on aluminum

    NASA Astrophysics Data System (ADS)

    Zhang, Haifeng; Yin, Liang; Liu, Xiaowei; Weng, Rui; Wang, Yang; Wu, Zhiwen

    2016-09-01

    We present a novel method to fabricate Zn-Al LDH (layered double hydroxides) film with 3D flower-like micro-and nanostructure on the aluminum foil. The wettability of the Zn-Al LDH film can be easily changed from superhydrophilic to superhydrophobic with a simple chemical modification. The as-prepared superhydrophobic surfaces have water CAs (contact angles) of 165 ± 2°. In order to estimate the drag reduction property of the surface with different adhesion properties, the experimental setup of the liquid/solid friction drag is proposed. The drag reduction ratio for the as-prepared superhydrophobic sample is 20-30% at low velocity. Bearing this in mind, we construct superhydrophobic surfaces that have numerous technical applications in drag reduction field.

  10. Layered double hydroxides toward electrochemical energy storage and conversion: design, synthesis and applications.

    PubMed

    Shao, Mingfei; Zhang, Ruikang; Li, Zhenhua; Wei, Min; Evans, David G; Duan, Xue

    2015-11-14

    Two-dimensional (2D) materials have attracted increasing interest in electrochemical energy storage and conversion. As typical 2D materials, layered double hydroxides (LDHs) display large potential in this area due to the facile tunability of their composition, structure and morphology. Various preparation strategies, including in situ growth, electrodeposition and layer-by-layer (LBL) assembly, have been developed to directly modify electrodes by using LDH materials. Moreover, several composite materials based on LDHs and conductive matrices have also been rationally designed and employed in supercapacitors, batteries and electrocatalysis with largely enhanced performances. This feature article summarizes the latest developments in the design, preparation and evaluation of LDH materials toward electrochemical energy storage and conversion. PMID:26459951

  11. Zn-Co layered double hydroxide modified hematite photoanode for enhanced photoelectrochemical water splitting

    NASA Astrophysics Data System (ADS)

    Xu, Dongyu; Rui, Yichuan; Li, Yaogang; Zhang, Qinghong; Wang, Hongzhi

    2015-12-01

    Zinc-cobalt layered double hydroxide (LDH) was electrodeposited on Ti-doped hematite photoanodes for the first time, and a significant enhanced performance for photoelectrochemical water splitting was demonstrated over the composite photoanodes. Scanning electron microscopy (SEM), X-ray diffraction (XRD), Fourier transform infrared spectroscopy (FTIR) and electrochemical impedance spectroscopy (EIS) were characterized with the resulted photoanodes. With the electrodepositing treatment, the photocurrent density increased from 1.27 mA/cm2 for pristine hematite to 1.73 mA/cm2 for modified materials at 1.23 V vs. RHE (i.e. 36% improvement). The photocurrent improvement is mainly attributed to a suppression of electron-hole recombination and reduced overpotential for water oxidation at the hematite-electrolyte interface due to the formation of Zn-Co LDH layer on hematite.

  12. Photostability enhancement of azoic dyes adsorbed and intercalated into Mg-Al-layered double hydroxide

    NASA Astrophysics Data System (ADS)

    Liu, Pengfei; Liu, Pei; Zhao, Kongcao; Li, Lei

    2015-11-01

    Two azoic dyes 4-aminoazobenzene-4-sulfonic (AS) and ethyl orange (EO) were adsorbed on or intercalated into Mg-Al-CO3 layered double hydroxide (LDH) for photostability enhancement. Fluorescence analysis results showed that the photostability of two dyes could be greatly improved after being adsorbed on the surface of Mg-Al-CO3-LDH matrix. Furthermore, photostability of adsorbed dyes was superior to that of intercalated dyes. It was suggested that AS or EO was adsorbed on LDHs surface through a strong chemisorption interaction, resulting in the enhancement of photostability. After the UV irradiation under N2 atmosphere, the absorbed dyes not only show great increase of fluorescence intensity but also exhibited high stability against UV irradiation. This work provides a feasible approach to enhance the photostability of azoic dye confined in an inorganic two-dimensional (2D) matrix via changing the microenvironment, which may be considered to be a promising method of improving photostability of solid fluorescent materials.

  13. Intercalation of p-methycinnamic acid anion into Zn-Al layered double hydroxide to improve UV aging resistance of asphalt

    NASA Astrophysics Data System (ADS)

    Peng, Chao; Dai, Jing; Yu, Jianying; Yin, Jian

    2015-02-01

    A UV absorber, p-methycinnamic acid (PMCA), was intercalated into Zn-Al layered double hydroxide (LDH) by calcination recovery. Fourier transform infrared spectroscopy showed that the PMCA anions completely replaced the CO32- anions in the interlayer galleries of Zn-Al-LDH containing PMCA anions (Zn-Al-PMCA-LDH). X-ray diffraction and transmission electron microscopy showed that the interlayer distance increased from 0.78 nm to 1.82 nm after the substitution of PMCA anions for CO32- anions. The similar diffraction angles of the CO32- anion-containing Zn-Al-LDH (Zn-Al-CO32--LDH) and the Zn-Al-CO32--LDH/styrene-butadiene-styrene (SBS) modified asphalt implied that the asphalt molecules do not enter into the LDH interlayer galleries to form separated-phase structures. The different diffraction angles of Zn-Al-PMCA-LDH and Zn-Al-PMCA-LDH/SBS modified asphalt indicated that the asphalt molecules penetrated into the LDH interlayer galleries to form an expanded-phase structure. UV-Vis absorbance analyses showed that Zn-Al-PMCA-LDH was better able to block UV light due to the synergistic effects of PMCA and Zn-Al-LDH. Conventional physical tests and atomic force microscopy images of the SBS modified asphalt, Zn-Al-CO32--LDH/SBS modified asphalt and Zn-Al-PMCA-LDH/SBS modified asphalt before and after UV aging indicated that Zn-Al-PMCA-LDH improved the UV aging resistance of SBS modified asphalts.

  14. Intercalation of p-methycinnamic acid anion into Zn-Al layered double hydroxide to improve UV aging resistance of asphalt

    SciTech Connect

    Peng, Chao; Dai, Jing; Yu, Jianying; Yin, Jian

    2015-02-15

    A UV absorber, p-methycinnamic acid (PMCA), was intercalated into Zn-Al layered double hydroxide (LDH) by calcination recovery. Fourier transform infrared spectroscopy showed that the PMCA anions completely replaced the CO{sub 3}{sup 2−} anions in the interlayer galleries of Zn-Al-LDH containing PMCA anions (Zn-Al-PMCA-LDH). X-ray diffraction and transmission electron microscopy showed that the interlayer distance increased from 0.78 nm to 1.82 nm after the substitution of PMCA anions for CO{sub 3}{sup 2−} anions. The similar diffraction angles of the CO{sub 3}{sup 2−} anion-containing Zn-Al-LDH (Zn-Al-CO{sub 3}{sup 2−}-LDH) and the Zn-Al-CO{sub 3}{sup 2−}-LDH/styrene–butadiene–styrene (SBS) modified asphalt implied that the asphalt molecules do not enter into the LDH interlayer galleries to form separated-phase structures. The different diffraction angles of Zn-Al-PMCA-LDH and Zn-Al-PMCA-LDH/SBS modified asphalt indicated that the asphalt molecules penetrated into the LDH interlayer galleries to form an expanded-phase structure. UV-Vis absorbance analyses showed that Zn-Al-PMCA-LDH was better able to block UV light due to the synergistic effects of PMCA and Zn-Al-LDH. Conventional physical tests and atomic force microscopy images of the SBS modified asphalt, Zn-Al-CO{sub 3}{sup 2−}-LDH/SBS modified asphalt and Zn-Al-PMCA-LDH/SBS modified asphalt before and after UV aging indicated that Zn-Al-PMCA-LDH improved the UV aging resistance of SBS modified asphalts.

  15. Preparation of Nickel-Aluminum-Containing Layered Double Hydroxide Films by Secondary (Seeded) Growth Method and Their Electrochemical Properties.

    PubMed

    Zhang, Fazhi; Guo, Li; Xu, Sailong; Zhang, Rong

    2015-06-23

    Thin films of nickel-aluminum-containing layered double hydroxide (NiAl-LDH) have been prepared on nickel foil and nickel foam substrates by secondary (seeded) growth of NiAl-LDH seed layer. The preparation procedure consists of deposition of LDH seeds from a colloidal suspension on the substrate by dip coating, followed by hydrothermal treatment of the nanocrystals to form the LDH film. The secondary grown film is found to provide a higher crystallinity and more uniform composition of metal cations in the film layer than the in situ grown film on seed-free substrate under identical hydrothermal conditions. A systematic investigation of the film evolution process reveals that the crystallite growth rate is relatively fast for the secondary grown film because of the presence of LDH nanocrystal seeds. Electrochemical performance of the resulting NiAl-LDH films as positive electrode material was further assessed as an example of their practical applications. The secondary grown film electrode delivers improved recharge-discharge capacity and cycling stability compared with that of the in situ grown film, which can be explained by the existence of a unique microstructure of the former. Our findings show an example for the effective fabrication of LDH film with controllable microstructure and enhanced application performance through a secondary (seeded) growth procedure. PMID:26033419

  16. The in vitro and in vivo anti-tumor effect of layered double hydroxides nanoparticles as delivery for podophyllotoxin.

    PubMed

    Qin, Lili; Xue, Meng; Wang, Wenrui; Zhu, Rongrong; Wang, Shilong; Sun, Jing; Zhang, Rui; Sun, Xiaoyu

    2010-03-30

    In this research, we intercalated anti-tumor drug podophyllotoxin (PPT) into layered double hydroxides (LDHs) and investigated the in vitro cytotoxicity to tumor cells, the cellular uptake and in vivo anti-tumor inhibition of PPT-LDH. The nanohybrids were prepared by a two-step method with the size of 80-90nm and the zeta potential of 20.3mV. The in vitro cytotoxicity experiment indicated that PPT-LDH nanoparticles show better anti-tumor efficacy than PPT and are more readily taken up by Hela cells. PPT-LDH shows a long-term suppression effect on the tumor growth, and enhances the apoptotic process of tumor cells. The in vivo tests reveal that delivery of PPT via LDH nanoparticles is more efficient, but the mice toxicity of PPT in PPT-LDH hybrids is reduced in comparison with PPT alone. Pharmacokinetics study displays a prolonged circulation time and an increased bioavailability of PPT-LDH than PPT. These observations imply that LDH nanoparticles are the potential carrier of anti-tumor drugs in a range of new therapeutic applications. PMID:20045452

  17. Layered Double Hydroxide Nanoplatelets with Excellent Tribological Properties under High Contact Pressure as Water-Based Lubricant Additives

    PubMed Central

    Wang, Hongdong; Liu, Yuhong; Chen, Zhe; Wu, Bibo; Xu, Sailong; Luo, Jianbin

    2016-01-01

    High efficient and sustainable utilization of water-based lubricant is essential for saving energy. In this paper, a kind of layered double hydroxide (LDH) nanoplatelets is synthesized and well dispersed in water due to the surface modification with oleylamine. The excellent tribological properties of the oleylamine-modified Ni-Al LDH (NiAl-LDH/OAm) nanoplatelets as water-based lubricant additives are evaluated by the tribological tests in an aqueous environment. The modified LDH nanoplatelets are found to not only reduce the friction but also enhance the wear resistance, compared with the water-based cutting fluid and lubricants containing other particle additives. By adding 0.5 wt% LDH nanoplatelets, under 1.5 GPa initial contact pressure, the friction coefficient, scar diameter, depth and width of the wear track dramatically decrease by 83.1%, 43.2%, 88.5% and 59.5%, respectively. It is considered that the sufficiently small size and the excellent dispersion of NiAl-LDH/OAm nanoplatelets in water are the key factors, so as to make them enter the contact area, form a lubricating film and prevent direct collision of asperity peaks. Our investigations demonstrate that the LDH nanoplatelet as a water-based lubricant additive has a great potential value in industrial application. PMID:26951794

  18. Layered Double Hydroxide Nanoplatelets with Excellent Tribological Properties under High Contact Pressure as Water-Based Lubricant Additives

    NASA Astrophysics Data System (ADS)

    Wang, Hongdong; Liu, Yuhong; Chen, Zhe; Wu, Bibo; Xu, Sailong; Luo, Jianbin

    2016-03-01

    High efficient and sustainable utilization of water-based lubricant is essential for saving energy. In this paper, a kind of layered double hydroxide (LDH) nanoplatelets is synthesized and well dispersed in water due to the surface modification with oleylamine. The excellent tribological properties of the oleylamine-modified Ni-Al LDH (NiAl-LDH/OAm) nanoplatelets as water-based lubricant additives are evaluated by the tribological tests in an aqueous environment. The modified LDH nanoplatelets are found to not only reduce the friction but also enhance the wear resistance, compared with the water-based cutting fluid and lubricants containing other particle additives. By adding 0.5 wt% LDH nanoplatelets, under 1.5 GPa initial contact pressure, the friction coefficient, scar diameter, depth and width of the wear track dramatically decrease by 83.1%, 43.2%, 88.5% and 59.5%, respectively. It is considered that the sufficiently small size and the excellent dispersion of NiAl-LDH/OAm nanoplatelets in water are the key factors, so as to make them enter the contact area, form a lubricating film and prevent direct collision of asperity peaks. Our investigations demonstrate that the LDH nanoplatelet as a water-based lubricant additive has a great potential value in industrial application.

  19. Layered Double Hydroxide Nanoplatelets with Excellent Tribological Properties under High Contact Pressure as Water-Based Lubricant Additives.

    PubMed

    Wang, Hongdong; Liu, Yuhong; Chen, Zhe; Wu, Bibo; Xu, Sailong; Luo, Jianbin

    2016-01-01

    High efficient and sustainable utilization of water-based lubricant is essential for saving energy. In this paper, a kind of layered double hydroxide (LDH) nanoplatelets is synthesized and well dispersed in water due to the surface modification with oleylamine. The excellent tribological properties of the oleylamine-modified Ni-Al LDH (NiAl-LDH/OAm) nanoplatelets as water-based lubricant additives are evaluated by the tribological tests in an aqueous environment. The modified LDH nanoplatelets are found to not only reduce the friction but also enhance the wear resistance, compared with the water-based cutting fluid and lubricants containing other particle additives. By adding 0.5 wt% LDH nanoplatelets, under 1.5 GPa initial contact pressure, the friction coefficient, scar diameter, depth and width of the wear track dramatically decrease by 83.1%, 43.2%, 88.5% and 59.5%, respectively. It is considered that the sufficiently small size and the excellent dispersion of NiAl-LDH/OAm nanoplatelets in water are the key factors, so as to make them enter the contact area, form a lubricating film and prevent direct collision of asperity peaks. Our investigations demonstrate that the LDH nanoplatelet as a water-based lubricant additive has a great potential value in industrial application. PMID:26951794

  20. Hierarchical Ni-Co layered double hydroxide nanosheets entrapped on conductive textile fibers: a cost-effective and flexible electrode for high-performance pseudocapacitors

    NASA Astrophysics Data System (ADS)

    Nagaraju, Goli; Raju, G. Seeta Rama; Ko, Yeong Hwan; Yu, Jae Su

    2015-12-01

    Hierarchical three-dimensional (3D) porous nanonetworks of nickel-cobalt layered double hydroxide (Ni-Co LDH) nanosheets (NSs) are grown and decorated on flexible conductive textile substrate (CTs) via a simple two-electrode system based electrochemical deposition (ED) method. By applying a proper external cathodic voltage of -1.2 V for 15 min, the Ni-Co LDH NSs are densely deposited over the entire surface of the CTs with good adhesion. The flexible Ni-Co LDH NSs on CTs (Ni-Co LDH NSs/CTs) architecture with high porosity facilitates enhanced electrochemical performance in 1 M KOH electrolyte solution. The effect of growth concentration and external cathodic voltage on the electrochemical properties of Ni-Co LDH NSs/CTs is also investigated. The Ni10Co5 LDH NSs/CTs electrode exhibits a high specific capacitance of 2105 F g-1 at a current density of 2 A g-1 as well as an excellent cyclic stability as a pseudocapacitive electrode due to the advantageous properties of 3D interconnected porous frameworks of Ni10Co5 LDH NSs/CTs. This facile fabrication of bimetallic hydroxide nanostructures on CTs can provide a promising electrode for low-cost energy storage device applications.Hierarchical three-dimensional (3D) porous nanonetworks of nickel-cobalt layered double hydroxide (Ni-Co LDH) nanosheets (NSs) are grown and decorated on flexible conductive textile substrate (CTs) via a simple two-electrode system based electrochemical deposition (ED) method. By applying a proper external cathodic voltage of -1.2 V for 15 min, the Ni-Co LDH NSs are densely deposited over the entire surface of the CTs with good adhesion. The flexible Ni-Co LDH NSs on CTs (Ni-Co LDH NSs/CTs) architecture with high porosity facilitates enhanced electrochemical performance in 1 M KOH electrolyte solution. The effect of growth concentration and external cathodic voltage on the electrochemical properties of Ni-Co LDH NSs/CTs is also investigated. The Ni10Co5 LDH NSs/CTs electrode exhibits a high

  1. Natural curcuminoids encapsulated in layered double hydroxides: a novel antimicrobial nanohybrid.

    PubMed

    Megalathan, Ajona; Kumarage, Sajeewani; Dilhari, Ayomi; Weerasekera, Manjula M; Samarasinghe, Siromi; Kottegoda, Nilwala

    2016-01-01

    Currently, there is an increased scientific interest to discover plant based drug formulations with improved therapeutic potential. Among the cornucopia of traditional medicinal plants, Curcuma longa rhizomes have been used as a powerful antibacterial and antifungal agent. However, its practical applications are limited due to its instability under thermal and UV radiation and its low bioavailability and the extensive procedures needed for isolation. This study focuses on exploring the potential of nanotechnology-based approaches to stabilize the natural curcuminoids, the major active components in turmeric without the need for its isolation, and to evaluate the release characteristics, stability and antimicrobial activity of the resulting nanohybrids. Natural curcuminoids were selectively encapsulated into nanolayers present in Mg-Al-layered double hydroxides (LDHs) using a method that avoids any isolation of the curcuminoids. The products were characterized using solid state techniques, while thermal and photo-stability were studied using thermogravimetric analysis (TGA) and UV exposure data. The morphological features were studied using scanning electron microscope (SEM) and transmission electron microscope (TEM). Drug release characteristics of the nanohybrid were quantitatively monitored under pH 3 and 5, and therapeutic potentials were assessed by using distinctive kinetic models. Finally, the antimicrobial activity of curcuminoids-LDH was tested against three bacterial and two fungal species. Powder X-ray diffraction, Fourier transform infra-red spectroscopy, SEM and TEM data confirmed the successful and selective encapsulation of curcuminoids in the LDH, while the TGA and UV exposure data suggested the stabilization of curcuminoids within the LDH matrix. The LDH demonstrated a slow and a sustained release of the curcuminoids in an acidic medium, while it was active against the three bacteria and two fungal species used in this study, suggesting its

  2. New synthetic route to Mg–Al–CO{sub 3} layered double hydroxide using magnesite

    SciTech Connect

    Wang, Xiaobo; Bai, Zhimin; Zhao, Dong; Chai, Yupu; Guo, Man; Zhang, Jingyu

    2013-03-15

    Highlights: ► The use of magnesite to prepare Mg–Al–CO{sub 3} LDH is novel. ► The result sample is systematically studied. ► Furthermore, the cost of preparing Mg–Al–CO{sub 3} LDH may be reduced through this synthetic route. ► In the synthesis process, there is no CO{sub 2} released. That is significant to environmental protection. - Abstract: A novel synthesis of Mg–Al–CO{sub 3} layered double hydroxide (LDH) through chemical precipitation and hydrothermal methods has been investigated in this paper. The advantages of this method are using magnesite as magnesium source and no CO{sub 2} released in the process of preparation. Mg–Al–CO{sub 3} LDH (ZY) prepared under the optimized condition (the molar ratio of magnesite and Al(NO{sub 3}){sub 3}·9H{sub 2}O was 2.5:1; the aging time and temperature were 16 h and 100 °C, respectively) was characterized by X-ray diffraction (XRD), Fourier transform infrared spectroscopy (FT-IR), thermo-gravimetric and differential thermal analyser (TG–DTA) and scanning electron microscope (SEM). The crystal morphology of the prepared LDH displays platelet-like structure with a hexagonal shape, which is agreed with the LDH produced by industrial chemicals. Through elemental analysis and inductively coupled plasma-atomic emission spectrometry (ICP-AES), the chemical formula of ZY is determined as Mg{sub 0.70}Al{sub 0.30}(OH){sub 2}(CO{sub 3}){sub 0.15}·0.6H{sub 2}O.

  3. A thermochromic thin film based on host-guest interactions in a layered double hydroxide.

    PubMed

    Wang, Xinrui; Lu, Jun; Shi, Wenying; Li, Feng; Wei, Min; Evans, David G; Duan, Xue

    2010-01-19

    Optically transparent thin films with thermochromic properties have been fabricated by means of cointercalation of different molar ratios of 4-(4-anilinophenylazo)benzenesulfonate (AO5) and sodium dodecylbenzene sulfonate (SDS) into the galleries of a ZnAl layered double hydroxide (LDH). The X-ray diffraction (XRD) patterns of these thin films show that they are assembled in a highly c-oriented manner, and the basal spacing ranges from 2.95 to 2.63 nm with varying AO5/SDS molar ratio. The preferential orientation of AO5 in the galleries of 10% AO5-LDH (AO5/SDS = 10:90, molar percentage) was evaluated by the fluorescence polarization technique; the results show that AO5 anions are accommodated between sheets of ZnAl-LDH as monomeric units with a tilt angle Psi (defined as the angle between the transition dipole moment of the AO5 anion with respect to the normal to the LDH layer) of 74 degrees. It was found that the composite film exhibits marked thermochromic behavior (light yellow <==> reddish-orange) in the temperature range of 35-65 degrees C, which is reversible over a number of heating-cooling cycles. It has been demonstrated that the thermochromic behavior results from tautomerism of interlayer AO5 and furthermore that both the host-guest and guest-guest interactions are key factors, since pristine AO5 shows no thermochromic performance. The 10% AO5-LDH film shows the highest thermochromic efficiency of all the films examined. Furthermore, a reversible contraction and expansion of the LDH basal spacing was also observed for this thin film over the same temperature range. PMID:19761228

  4. Dual nutraceutical nanohybrids of folic acid and calcium containing layered double hydroxides

    NASA Astrophysics Data System (ADS)

    Kim, Tae-Hyun; Oh, Jae-Min

    2016-01-01

    Dual nutraceutical nanohybrids consisting of organic nutrient, folic acid (FA), and mineral nutrient, calcium, were prepared based on layered double hydroxide (LDH) structure. Among various hybridization methods such as coprecipitation, ion exchange, solid phase reaction and exfoliation-reassembly, it was found that exfoliation-reassembly was the most effective in terms of intercalation of FA moiety between Ca-containing LDH layers. X-ray diffraction patterns and infrared spectra indicated that FA molecules were well stabilized in the interlayer space of LDHs through electrostatic interaction. From the atomic force and scanning electron microscopic studies, particle thickness of LDH was determined to be varied with tens, a few and again tens of nanometers in pristine, exfoliated and reassembled state, respectively, while preserving particle diameter. The result confirmed layer-by-layer hybrid structure of FA and LDHs was obtained by exfoliation-reassembly. Solid UV-vis spectra showed 2-dimensional molecular arrangement of FA moiety in hybrid, exhibiting slight red shift in n→π* and π→π* transition. The chemical formulae of FA intercalated Ca-containing LDH were determined to Ca1.30Al(OH)4.6FA0.74·3.33H2O and Ca1.53Fe(OH)5.06FA2.24·9.94H2O by inductively coupled plasma-atomic emission spectroscopy, high performance liquid chromatography and thermogravimetry, showing high nutraceutical content of FA and Ca.

  5. Novel biohybrids of layered double hydroxide and lactate dehydrogenase enzyme: Synthesis, characterization and catalytic activity studies

    NASA Astrophysics Data System (ADS)

    Djebbi, Mohamed Amine; Braiek, Mohamed; Hidouri, Slah; Namour, Philippe; Jaffrezic-Renault, Nicole; Ben Haj Amara, Abdesslem

    2016-02-01

    The present work introduces new biohybrid materials involving layered double hydroxides (LDH) and biomolecule such as enzyme to produce bioinorganic system. Lactate dehydrogenase (Lac Deh) has been chosen as a model enzyme, being immobilized onto MgAl and ZnAl LDH materials via direct ion-exchange (adsorption) and co-precipitation methods. The immobilization efficiency was largely dependent upon the immobilization methods. A comparative study shows that the co-precipitation method favors the immobilization of great and tunable amount of enzyme. The structural behavior, chemical bonding composition and morphology of the resulting biohybrids were determined by X-ray diffraction (XRD) study, Fourier transform infrared (FTIR) spectroscopy and transmission electron microscopy (TEM), respectively. The free and immobilized enzyme activity and kinetic parameters were also reported using UV-Visible spectroscopy. However, the modified LDH materials showed a decrease in crystallinity as compared to the unmodified LDH. The change in activity of the immobilized lactate dehydrogenase was considered to be due, to the reduced accessibility of substrate molecules to the active sites of the enzyme and the partial conformational change of the Lac Deh molecules as a result of the immobilization way. Finally, it was proven that there is a correlation between structure/microstructure and enzyme activity dependent on the immobilization process.

  6. Fire and thermal properties of layered double hydroxides and polyurea nanocomposites

    NASA Astrophysics Data System (ADS)

    Nyambo, Calistor

    Layered double hydroxide (LDH) intercalated with linear alkyl carboxylates (CH3(CH2)n COO-, n = 8, 10, 12, 14, 16, 20), borate and benzyl anions were prepared. The effect on fire and thermal properties of the mode of preparation for LDHs (i.e. ion exchange, coprecipitation and rehydration of the calcined LDH methods) has been studied. After characterization, the LDHs were used to prepare nanocomposites with a range of polar and non-polar polymers. Characterization of the LDHs and the nanocomposites was performed using Fourier transform infrared spectroscopy (FTIR), X-ray diffraction (XRD), thermogravimetry analysis (TGA), transmission electron microscopy (TEM) and cone calorimetry. FTIR and XRD analyses confirmed the presence of the charge balancing anions in the galleries of the LDHs. Improvements in fire and thermal properties of the nanocomposites were observed. The cone calorimeter revealed that the addition of LDHs reduces the peak heat release rate significantly. LDHs were combined with commercial fire retardants. Synergistic effects were observed in both TGA and cone calorimetry for formulations containing both LDH and ammonium polyphosphate (APP). Physical and chemical interactions between LDH and APP are responsible for the observed synergy in thermal stability and fire performance.

  7. Thermal, solution and reductive decomposition of Cu-Al layered double hydroxides into oxide products

    SciTech Connect

    Britto, Sylvia; Vishnu Kamath, P.

    2009-05-15

    Cu-Al layered double hydroxides (LDHs) with [Cu]/[Al] ratio 2 adopt a structure with monoclinic symmetry while that with the ratio 0.25 adopt a structure with orthorhombic symmetry. The poor thermodynamic stability of the Cu-Al LDHs is due in part to the low enthalpies of formation of Cu(OH){sub 2} and CuCO{sub 3} and in part to the higher solubility of the LDH. Consequently, the Cu-Al LDH can be decomposed thermally (150 deg. C), hydrothermally (150 deg. C) and reductively (ascorbic acid, ambient temperature) to yield a variety of oxide products. Thermal decomposition at low (400 deg. C) temperature yields an X-ray amorphous residue, which reconstructs back to the LDH on soaking in water or standing in the ambient. Solution decomposition under hydrothermal conditions yields tenorite at 150 deg. C itself. Reductive decomposition yields a composite of Cu{sub 2}O and Al(OH){sub 3}, which on alkali-leaching of the latter, leads to the formation of fine particles of Cu{sub 2}O (<1 {mu}m). - Graphical abstract: SEM image of (a) the Cu{sub 2}O-Al(OH){sub 3} composite obtained on reductive decomposition of CuAl{sub 4}-LDH and (b) Cu{sub 2}O obtained on leaching of Al(OH){sub 3} from (a).

  8. Layered Double Hydroxide Nanotransporter for Molecule Delivery to Intact Plant Cells.

    PubMed

    Bao, Wenlong; Wang, Junya; Wang, Qiang; O'Hare, Dermot; Wan, Yinglang

    2016-01-01

    Here we report a powerful method that facilitates the transport of biologically active materials across the cell wall barrier in plant cells. Positively charged delaminated layered double hydroxide lactate nanosheets (LDH-lactate-NS) with a 0.5‒2 nm thickness and 30‒60 nm diameter exhibit a high adsorptive capacity for negatively charged biomolecules, including fluorescent dyes such as tetramethyl rhodamine isothiocyanate (TRITC), fluorescein isothiocyanate isomer I(FITC) and DNA molecules, forming neutral LDH-nanosheet conjugates. These neutral conjugates can shuttle the bound fluorescent dye into the cytosol of intact plant cell very efficiently. Furthermore, typical inhibitors of endocytosis and low temperature incubation did not prevent LDH-lactate-NS internalization, suggesting that LDH-lactate-NS penetrated the plasma membrane via non-endocytic pathways, which will widen the applicability to a variety of plant cells. Moreover, the absence of unwanted side effects in our cytological studies, and the nuclear localization of ssDNA-FITC suggest that nano-LDHs have potential application as a novel gene carrier to plants. PMID:27221055

  9. Layered Double Hydroxide Nanotransporter for Molecule Delivery to Intact Plant Cells

    PubMed Central

    Bao, Wenlong; Wang, Junya; Wang, Qiang; O’Hare, Dermot; Wan, Yinglang

    2016-01-01

    Here we report a powerful method that facilitates the transport of biologically active materials across the cell wall barrier in plant cells. Positively charged delaminated layered double hydroxide lactate nanosheets (LDH-lactate-NS) with a 0.5‒2 nm thickness and 30‒60 nm diameter exhibit a high adsorptive capacity for negatively charged biomolecules, including fluorescent dyes such as tetramethyl rhodamine isothiocyanate (TRITC), fluorescein isothiocyanate isomer I(FITC) and DNA molecules, forming neutral LDH-nanosheet conjugates. These neutral conjugates can shuttle the bound fluorescent dye into the cytosol of intact plant cell very efficiently. Furthermore, typical inhibitors of endocytosis and low temperature incubation did not prevent LDH-lactate-NS internalization, suggesting that LDH-lactate-NS penetrated the plasma membrane via non-endocytic pathways, which will widen the applicability to a variety of plant cells. Moreover, the absence of unwanted side effects in our cytological studies, and the nuclear localization of ssDNA-FITC suggest that nano-LDHs have potential application as a novel gene carrier to plants. PMID:27221055

  10. Fe-Al layered double hydroxides in bromate reduction: Synthesis and reactivity.

    PubMed

    Chitrakar, Ramesh; Makita, Yoji; Sonoda, Akinari; Hirotsu, Takahiro

    2011-02-15

    This study presents a rare use of layered double hydroxides of Fe(II) and Al(III) (Fe-Al LDH), as reported for the first time for bromate removal from aqueous solutions. The Fe-Al LDH samples were prepared with Fe/Al molar ratios of 1-4 using a co-precipitation method at pH 7, with subsequent hydrothermal treatment at 120°C. The Fe-Al LDH (molar ratio of Fe/Al=1, 2) with a layered structure exhibited nearly complete removal of bromate from initial concentration of 100μmol/dm(3) at a wide pH range of 4.0-10.5 over a 2h reaction period; the residual bromate concentration in the solution was lower than the detection limit of 0.07μmol/dm(3) (9μg-BrO(3)(-)/dm(3)). During the reaction period, bromide was released into the solution via a reduction process. Reactivity of Fe-Al LDH with a Fe/Al molar ratio of 2 did not decrease the bromate reduction efficiency during 30days. PMID:21126742

  11. Two steps in situ structure fabrication of Ni-Al layered double hydroxide on Ni foam and its electrochemical performance for supercapacitors

    NASA Astrophysics Data System (ADS)

    Wang, Bin; Liu, Qi; Qian, Zhongyu; Zhang, Xiaofei; Wang, Jun; Li, Zhanshuang; Yan, Huijun; Gao, Zan; Zhao, Fangbo; Liu, Lianhe

    2014-01-01

    In this paper, two steps in situ growth method has been used to solve the accumulation of layered double hydroxide (LDH) in oriented growth. Moreover, the petal-like Ni-Al LDH displays excellent pseudocapacitance performance: a specific capacitance of 795 F g-1, a long cycle life with 80% performance remains after 1000 cycles and good charge/discharge stability, owing to the improvement of pseudocapacitive reaction by the large sheet structure of Ni-Al LDH on Ni foam. And the comparison results of different electrode preparation process and different growth process reflect the great advantages of our synthesis method.

  12. Mechano-hydrothermal synthesis of Mg{sub 2}Al–NO{sub 3} layered double hydroxides

    SciTech Connect

    Zhang, Fengrong; Du, Na; Song, Shue; Liu, Jianqiang; Hou, Wanguo

    2013-10-15

    A mechano-hydrothermal method was developed to synthesize Mg{sub 2}Al–NO{sub 3} layered double hydroxide (LDH) from MgO, Al{sub 2}O{sub 3} and NaNO{sub 3} as starting materials. A two-step synthesis was conducted, that is, a mixture of MgO and Al{sub 2}O{sub 3} was milled for 1 h, followed by hydrothermal treatment with NaNO{sub 3} solution. The resulting LDHs were characterized by X-ray diffraction, transmission electron microscopy, scanning electron microscopy, Fourier transform infrared and elemental analyses. Pre-milling played a key role in the LDH formation during subsequent hydrothermal treatment. The process is advantageous in terms of low reaction temperature and short reaction time compared with the conventional hydrothermal method, and the target products are of high crystallinity, good dispersion and regular shape compared with the conventional mechanochemical method. - Graphical abstract: The novel mechano-hydrothermal route to synthesize LDH has advantages in low reaction temperature and short reaction time, and the target product was of high crystallinity, good dispersion and regular shape. Display Omitted - Highlights: • A mechano-hydrothermal route was developed for layered double hydroxide synthesis. • Synthesis could be achieved at low temperature and in a short time. • Resulting layered double hydroxide samples were well dispersed and of regular shape. • A dissolution–recrystallization mechanism was proposed for the formation process.

  13. Phosphate-intercalated Ca-Fe-layered double hydroxides: Crystal structure, bonding character, and release kinetics of phosphate

    SciTech Connect

    Woo, Myong A.; Woo Kim, Tae; Paek, Mi-Jeong; Ha, Hyung-Wook; Choy, Jin-Ho; Hwang, Seong-Ju

    2011-01-15

    The nitrate-form of Ca-Fe-layered double hydroxide (Ca-Fe-LDH) was synthesized via co-precipitation method, and its phosphate-intercalates were prepared by ion-exchange reaction. According to X-ray diffraction analysis, the Ca-Fe-LDH-NO{sub 3}{sup -} compound and its H{sub 2}PO{sub 4}{sup -}-intercalate showed hexagonal layered structures, whereas the ion-exchange reaction with HPO{sub 4}{sup 2-} caused a frustration of the layer ordering of LDH. Fe K-edge X-ray absorption spectroscopy clearly demonstrated that the Ca-Fe-LDH lattice with trivalent iron ions was well-maintained after the ion-exchange with HPO{sub 4}{sup 2-} and H{sub 2}PO{sub 4}{sup -}. Under acidic conditions, phosphate ions were slowly released from the Ca-Fe-LDH lattice and the simultaneous release of hydroxide caused the neutralization of acidic media. Fitting analysis based on kinetic models indicated a heterogeneous diffusion process of phosphates and a distinct dependence of release rate on the charge of phosphates. This study strongly suggested that Ca-Fe-LDH is applicable as bifunctional vector for slow release of phosphate fertilizer and for the neutralization of acid soil. -- Graphical abstract: We synthesized phosphate-intercalated Ca-Fe-LDH materials that can act as bifunctional inorganic vectors for the slow release of phosphate fertilizer and also the neutralization of acid soil. Fitting analysis based on kinetic models indicated a heterogeneous diffusion process of phosphates and a distinct dependence of release rate on the charge of phosphates. Display Omitted Research Highlights: {yields} The phosphate forms of Ca-Fe-layered double hydroxide (Ca-Fe-LDH) were synthesized via co-precipitation method. The crystal structure, bonding character, and release kinetics of phosphate of the phosphate-intercalates were investigated. These Ca-Fe-LDH materials are applicable as bifunctional vector for slow release of phosphate fertilizer and for the neutralization of acid soil.

  14. Accessing the biocompatibility of layered double hydroxide by intramuscular implantation: histological and microcirculation evaluation.

    PubMed

    Cunha, Vanessa Roberta Rodrigues; de Souza, Rodrigo Barbosa; da Fonseca Martins, Ana Maria Cristina Rebello Pinto; Koh, Ivan Hong Jun; Constantino, Vera Regina Leopoldo

    2016-01-01

    Biocompatibility of layered double hydroxides (LDHs), also known as hydrotalcite-like materials or double metal hydroxides, was investigated by in vivo assays via intramuscular tablets implantation in rat abdominal wall. The tablets were composed by chloride ions intercalated into LDH of magnesium/aluminum (Mg2Al-Cl) and zinc/aluminum (Zn2Al-Cl). The antigenicity and tissue integration capacity of LDHs were assessed histologically after 7 and 28 days post-implantation. No fibrous capsule nearby the LDH was noticed for both materials as well any sign of inflammatory reactions. Sidestream Dark Field imaging, used to monitor in real time the microcirculation in tissues, revealed overall integrity of the microcirculatory network neighboring the tablets, with no blood flow obstruction, bleeding and/or increasing of leukocyte endothelial adhesion. After 28 days Mg2Al-Cl promoted multiple collagen invaginations (mostly collagen type-I) among its fragments while Zn2Al-Cl induced predominantly collagen type-III. This work supports previous results in the literature about LDHs compatibility with living matter, endorsing them as functional materials for biomedical applications. PMID:27480483

  15. Accessing the biocompatibility of layered double hydroxide by intramuscular implantation: histological and microcirculation evaluation

    PubMed Central

    Cunha, Vanessa Roberta Rodrigues; de Souza, Rodrigo Barbosa; da Fonseca Martins, Ana Maria Cristina Rebello Pinto; Koh, Ivan Hong Jun; Constantino, Vera Regina Leopoldo

    2016-01-01

    Biocompatibility of layered double hydroxides (LDHs), also known as hydrotalcite-like materials or double metal hydroxides, was investigated by in vivo assays via intramuscular tablets implantation in rat abdominal wall. The tablets were composed by chloride ions intercalated into LDH of magnesium/aluminum (Mg2Al-Cl) and zinc/aluminum (Zn2Al-Cl). The antigenicity and tissue integration capacity of LDHs were assessed histologically after 7 and 28 days post-implantation. No fibrous capsule nearby the LDH was noticed for both materials as well any sign of inflammatory reactions. Sidestream Dark Field imaging, used to monitor in real time the microcirculation in tissues, revealed overall integrity of the microcirculatory network neighboring the tablets, with no blood flow obstruction, bleeding and/or increasing of leukocyte endothelial adhesion. After 28 days Mg2Al-Cl promoted multiple collagen invaginations (mostly collagen type-I) among its fragments while Zn2Al-Cl induced predominantly collagen type–III. This work supports previous results in the literature about LDHs compatibility with living matter, endorsing them as functional materials for biomedical applications. PMID:27480483

  16. Synthesis and release behavior of composites of camptothecin and layered double hydroxide

    SciTech Connect

    Dong Lun; Yan Li; Hou Wanguo; Liu Shaojie

    2010-08-15

    A simple method, reconstruction of calcinated layered double hydroxides (CLDH) in an organic (ethanol)-water mixed solvent medium containing drug, was developed to intercalate partially a non-ionic and poorly water-soluble drug (camptothecin) into the gallery of layered double hydroxides (LDHs) to form the drug-LDH composites. The purpose of choosing organic-water mixed solvent is to increase remarkably the solubility of camptothecin (CPT) in the reconstruction medium. A probable morphology of CPT molecules in the gallery of LDHs is that CPT molecules arrange as monolayer with the long axis parallel to the LDH layers. The in vitro drug release from the composites was remarkably lower than that from the corresponding physical mixture, which shows these drug-inorganic composites can be used as a potential drug delivery system. - Graphical abstract: A simple method, reconstruction of calcinated LDHs in an organic-water medium containing drug, was developed to intercalate non-ionic and poorly water-soluble camptothecin into the gallery of LDHs.

  17. Intercalation of biomolecules into NiAl-NO 3 layered double hydroxide films synthesized in situ on anodic alumina/aluminium support

    NASA Astrophysics Data System (ADS)

    Zhao, Hua-Zhang; Chang, Ying-Yue; Yang, Jing; Yang, Qin-Zheng

    2013-03-01

    Layered double hydroxide (LDH) films were synthesized in situ on anodic alumina/aluminium (AAO/Al). Glucose oxidase (GOD) and L-ascorbic acid (vitamin C, VC) were intercalated respectively into the in-situ grown LDH films by anion-exchange in aqueous solutions. Dodecylsulfate (SDS) was used to expand the lamellar structure before GOD intercalation into the LDH film. The resulting products were characterized by scanning electron microscopy (SEM), x-ray diffraction (XRD), Fourier transform infrared (FTIR) spectroscopy and thermo gravimetric analysis (TGA). The results showed that VC and GOD were successfully intercalated into the in-situ synthesized LDH film. These biomolecules loaded LDH films could have potential applications in electrode modification, safe storage and effective delivery of bioactive compounds.

  18. Chemisorption Mechanism of DNA on Mg/Fe Layered Double Hydroxide Nanoparticles: Insights into Engineering Effective SiRNA Delivery Systems.

    PubMed

    Lu, Mingsheng; Shan, Zhi; Andrea, Kori; MacDonald, Bruce; Beale, Stefanie; Curry, Dennis E; Wang, Li; Wang, Shujun; Oakes, Ken D; Bennett, Craig; Wu, Wenhui; Zhang, Xu

    2016-03-22

    Layered double hydroxide nanoparticles (LDH NPs) have attracted interest as an effective gene delivery vehicle in biomedicine. Recent advances in clinic trials have demonstrated the efficacy of Mg/Fe LDHs for hyperphosphatemia treatment, but their feasibility for gene delivery has not been systematically evaluated. As a starting point, we aimed to study the interaction between oligo-DNA and Mg/Fe LDH NPs. Our investigation revealed the chemisorption mechanism of DNA on Mg/Fe LDH surfaces, wherein the phosphate backbone of the DNA polymer coordinates with the metal cations of the LDH lattice via the ligand-exchange process. This mechanistic insight may facilitate future gene delivery applications using Mg/Fe LDH NPs. PMID:26919981

  19. Facile synthesis of novel two-dimensional silver-coated layered double hydroxide nanosheets as advanced anode material for Ni-Zn secondary batteries

    NASA Astrophysics Data System (ADS)

    Yang, Bin; Yang, Zhanhong; Wang, Ruijuan

    2014-04-01

    Silver-coated layered double hydroxide (Ag-coated LDH) nanosheets are successfully prepared by a facile silver mirror reaction and their electrochemical performance has been evaluated as anode materials for Ni-Zn secondary batteries. The microstructure and morphology of as-prepared Ag-coated Zn/Al-LDH are investigated by scanning electron microscopy (SEM), transmission electron microscopy (TEM) and X-ray diffraction (XRD). As anode material for Ni-Zn secondary batteries, Ag-coated Zn/Al-LDH exhibits high specific capacity (400 mAh g-1), good charge-discharge properties and excellent cycling performance, which is attributed to the effect of the electron conductivity improvement by the Ag coating on the surface of Zn/Al-LDH nanosheet. This newly designed Ag-coated Zn/Al-LDH may offer a promising anode candidate for high-performance Ni-Zn secondary batteries.

  20. Improvement of pharmacokinetic and antitumor activity of layered double hydroxide nanoparticles by coating with PEGylated phospholipid membrane

    PubMed Central

    Yan, Mina; Zhang, Zhaoguo; Cui, Shengmiao; Lei, Ming; Zeng, Ke; Liao, Yunhui; Chu, Weijing; Deng, Yihui; Zhao, Chunshun

    2014-01-01

    Layered double hydroxide (LDH) has attracted considerable attention as a drug carrier. However, because of its poor in vivo behavior, polyethylene glycolylated (PEGylated) phospholipid must be used as a coformer to produce self-assembled core–shell nanoparticles. In the present study, we prepared a PEGylated phospholipid-coated LDH (PLDH) (PEG-PLDH) delivery system. The PEG-PLDH nanoparticles had an average size of 133.2 nm. Their core–shell structure was confirmed by transmission electron microscopy and X-ray photoelectron spectroscopy. In vitro liposome-cell-association and cytotoxicity experiments demonstrated its ability to be internalized by cells. In vivo studies showed that PEGylated phospholipid membranes greatly reduced the blood clearance rate of LDH nanoparticles. PEG-PLDH nanoparticles demonstrated a good control of tumor growth and increased the survival rate of mice. These results suggest that PEG-PLDH nanoparticles can be a useful drug delivery system for cancer therapy. PMID:25364245

  1. Gold Nanoparticles Supported on a Layered Double Hydroxide as Efficient Catalysts for the One-Pot Synthesis of Flavones.

    PubMed

    Yatabe, Takafumi; Jin, Xiongjie; Yamaguchi, Kazuya; Mizuno, Noritaka

    2015-11-01

    Flavones are a class of natural products with diverse biological activities and have frequently been synthesized by step-by-step procedures using stoichiometric amounts of reagents. Herein, a catalytic one-pot procedure for the synthesis of flavone and its derivatives is developed. In the presence of gold nanoparticles supported on a Mg-Al layered double hydroxide (Au/LDH), various kinds of flavones can be synthesized starting from 2'-hydroxyacetophenones and benzaldehydes (or benzyl alcohols). The present one-pot procedure consists of a sequence of several reactions, and Au/LDH can catalyze all these different types of reactions. The catalysis is shown to be truly heterogeneous, and Au/LDH can be readily recovered and reused. PMID:26367015

  2. Phosphorus-containing flame retardant modified layered double hydroxides and their applications on polylactide film with good transparency.

    PubMed

    Ding, Peng; Kang, Bai; Zhang, Jin; Yang, Jingwen; Song, Na; Tang, Shengfu; Shi, Liyi

    2015-02-15

    Polylactide (PLA)/layered double hydroxide (LDH) films with good flame retardant property and transparency were synthesized by solution exfoliation and film casting method. The organic-inorganic interfacial interaction between PLA and NiAl-LDH was carefully modified by 2-carboxylethyl-phenyl-phosphinic acid (CEPPA) to well solve the dispersion problem of NiAl-LDH nanolayers and get enhanced flame retardancy of PLA composites. The results showed the NiAl-LDH/CEPPA (LC) nanolayers had exfoliated structures and were homogenously dispersed in PLA matrixes. All the PLA/LDH films had good transparency even LC content was up to 10 wt%. The PLA/LDH films absorbed the ultraviolet light, which alleviates the embrittlement of PLA films in the using procedure. The flame retardant effect characterized by microscale combustion calorimeter was observed when LC contents increased. The total heat release value of the sample with 10 wt% LC decreased to 9.7 kJ/g from 12.0 kJ/g of virgin PLA. PMID:25460688

  3. Study of the structure and luminescent properties of terbium complex intercalated Zn/Al layered double hydroxide

    NASA Astrophysics Data System (ADS)

    Gao, Xiaorui; Xie, Juan; Yin, Yaobing; Hao, Yongjing; Lian, Yiwei

    2016-01-01

    Terbium complex of ethylenediaminetetraacetate ([Tb(EDTA)]-) intercalated Zn/Al layered double hydroxide (LDH), as an inorganic-organic green-emitting phosphor, was synthesized through an ion exchange method. X-ray powder diffraction (XRD) and Fourier transform infrared (FTIR) spectra exhibit a successful intercalation of [Tb(EDTA)]- anions between the hydroxide sheets of the LDH. The basal spacing of 14.5 Å indicate a vertical arrangement of [Tb(EDTA)]- anions with the maximal dimension in the gallery is adopted. The luminescent properties of this material were studied by excitation and emission spectra. The results show that the strongest emission peak of Tb3+ ion occurs at 544 nm. This material may supply a candidate of green light emitting phosphor.

  4. Effect of reaction time and (Ca+Mg)/Al molar ratios on crystallinity of Ca-Mg-Al layered double Hydroxide

    NASA Astrophysics Data System (ADS)

    Heraldy, E.; Nugrahaningtyas, K. D.; Sanjaya, F. B.; Darojat, A. A.; Handayani, D. S.; Hidayat, Y.

    2016-02-01

    Ca-Mg-Al Layered Double Hydroxides (Ca-Mg-Al-LDH) compounds were successfully synthesized from brine water and AlCl3.6H2O as the starting materials by coprecipitation method. The product result was characterized by X-ray powder diffraction (XRD) and Fourier transform infrared (FT-IR). The effects of the reaction time and the molar ratios of the raw material on the crystallinity of Ca-Mg-Al-LDH were examining. Results show that increasing reaction time (30; 60 and 90 min.) could improve the crystallinity and monodispersity of layered double hydroxide compounds particles. The well-defined Ca-Mg- Al-LDH could be prepared with (Ca+Mg)/Al molar ratios 0.5.

  5. Facile synthesis of methotrexate intercalated layered double hydroxides: particle control, structure and bioassay explore.

    PubMed

    Tian, De-Ying; Liu, Zhen-Lei; Li, Shu-Ping; Li, Xiao-Dong

    2014-12-01

    To study the influence of particle size on drug efficacy and other properties, a series of methotrexate intercalated layered double hydroxides (MTX/LDHs) were synthesized through the traditional coprecipitation method, using a mixture of water and polyethylene glycol (PEG-400) as the solvent. To adjust the particle size of MTX/LDHs, the dropping way, the volume ratio of water to PEG-400 and different hydrothermal treatment time changed accordingly, and the results indicate that the particle size can be controlled between 90 and 140 nm. Elemental C/H/N and inductive coupled plasma (ICP) analysis indicated that different synthesis conditions almost have no effect on the compositions of the nanohybrids. X-ray diffraction (XRD) patterns manifested the successful intercalation of MTX anions into the LDH interlayers, and it's also found out that different volume ratios of water to PEG-400 and variable dropping way can affect the crystallinity of the final samples, i.e., the volume ratio of 3:1 and pH decreasing are proved to be optimum conditions. Furthermore, both antiparallel monolayer and bilayers adopting different orientations are suggested for four samples from XRD results. Fourier transform infrared spectroscopy (FTIR) investigations proved the coexistence of CO3(2-) and MTX anions in the interlayer of the nanohybrids. MTX/LDH particles exhibited hexagonal platelet morphology with round corner and different dropping ways can affect the morphology greatly. Moreover, a DSC study indicated that longer time treatment can weaken the bond between the MTX anions and LDH layers. The kinetic release profiles told us that larger MTX/LDH particles have enhanced the ability of LDH layers to protect interlayer molecules. At last, the bioassay study indicated that the nanohybrids with larger diameters have higher tumor suppression efficiency. PMID:25491832

  6. Enhanced sequestration of Cr(VI) by nanoscale zero-valent iron supported on layered double hydroxide by batch and XAFS study.

    PubMed

    Sheng, Guodong; Hu, Jun; Li, Hui; Li, Jiaxing; Huang, Yuying

    2016-04-01

    Herein, the reduction of nanoscale zero-valent iron (NZVI) and adsorption of layered double hydroxides (LDH) to sequester Cr(VI) were well combined by the immobilization of NZVI onto LDH surface (NZVI/LDH). The characterization results revealed that LDH decreased NZVI aggregation and thus increased Cr(VI) sequestration. The batch results indicated that Cr(VI) sequestration by NZVI/LDH was higher than that of NZVI, and superior to the sum of reduction and adsorption. The LDH with good anion exchange property allowed the adsorption of Cr(VI), facilitating interfacial reaction by increasing the local concentration of Cr(VI) in the NZVI vicinity. X-ray absorption near edge structure (XANES) results indicated that Cr(VI) was almost completely reduced to Cr(III) by NZVI/LDH, but Cr(VI) was partly reduced to Cr(III) by NZVI with a trace of Cr(VI) adsorbed on corrosion products. The coordination environment of Cr from extended X-ray absorption fine structure (EXAFS) analysis revealed that LDH could be a good scavenger for the insoluble products produced during reaction. So, the insoluble products on NZVI could be reduced, and its reactivity could be maintained. These results demonstrated that NZVI/LDH exhibits multiple functionalities relevant to the remediation of Cr(VI)-contaminated sites. PMID:26807943

  7. Hybridization Between Natural Extract of Angelica gigas Nakai and Inorganic Nanomaterial of Layered Double Hydroxide via Reconstruction Reaction.

    PubMed

    Kim, Tae-Hyun; Kim, Hyoung-Jun; Choi, Ae-Jin; Choi, Hyun-Jin; Oh, Jae-Min

    2016-01-01

    We have hybridized layered double hydroxide (LDH) with Angelica gigas Nakai root extract (AGNR) through reversible dehydration-rehydration reaction which is known as reconstruction. LDHs having well-ordered hydrotalcite-like crystal structure and average size 250 ± 20 nm were prepared by hydrothermal method. The root of Angelica gigas Nakai, which has been utilized in the treatment of female disorders as herbal medicine, was treated with methanol to obtain extract. Pristine LDHs were calcined at 400 °C for 8 hours to obtain layered double oxide (LDO), which was further dispersed into extract solution with various AGNR/LDO weight ratios, 0.11, 0.21 and 0.43. The extract content in each hybrid increased in proportion to initial AGNR/LDO ratio, showing the highest content of ~12%. The zeta potential of LDH shifted from +44 mV to +20 mV upon hybridization with extract, which was attributed to the adsorption of negatively charged organic moieties in AGNR on LDH surface. The scanning electron microscopic (SEM) results exhibited that the random stacking of LDH nanolayers resulted in LDH-AGNR hybrid with house-of-cards structure, of which inter-particle cavity serves nano-reservoir for natural extract. According to quantitative analyses, it was revealed that the content of active components in AGNR increased when they were hybridized with LDHs compared with those in AGNR alone. PMID:27398576

  8. Compositional and Structural Control on Anion Sorption Capability of Layered Double Hydroxides (LDHS)

    SciTech Connect

    Y. Wang; H. Gao

    2006-03-16

    Layered double hydroxides (LDHs) have shown great promise as anion getters. In this paper, we demonstrate that the sorption capability of a LDH for a specific oxyanion can be greatly increased by appropriately manipulating material composition and structure. A large set of LDH materials have been synthesized with various combinations of metal cations, interlayer anions, and the molar ratios of divalent cation M(II) to trivalent cation M(III). The synthesized materials have then been tested systematically for their sorption capabilities for pertechnetate (TcO{sub 4}{sup -}). It is discovered that for a given interlayer anion (either CO{sub 3}{sup 2-} or NO{sub 3}{sup -}) the Ni-Al LDH with a Ni/Al ratio of 3:1 exhibits the highest sorption capability among all the materials tested. The distribution coefficient (K{sub d}) is determined to be as high as 307 mL/g for Ni{sub 6}Al{sub 2}(0H){sub 16}CO{sub 3}nH{sub 2}O and 1390 mL/g for Ni{sub 6}Al{sub 2}(OH){sub 16}NO{sub 3}nH{sub 2}O at a pH of 8. The sorption of TcO{sub 4}{sup -} on M(II)-M(III)-CO{sub 3} LDHs is dominated by the edge sites of LDH layers and strongly correlated with the basal spacing d{sub 003} of the materials, which increases with the decreasing radii of both divalent and trivalent cations. The sorption reaches its maximum when the layer spacing is just large enough for a pertechnetate anion to fit into a cage space between two neighboring octahedra of metal hydroxides at the edge. Furthermore, the sorption is found to increase with the crystallinity of the materials. For a given combination of metal cations and an interlayer anion, a best crystalline LDH material is obtained generally with a M(II)/M(III) ratio of 3:1. Replacement of interlayer carbonate with readily exchangeable nitrate greatly increases the sorption capability of a LDH material for pertechnetate, due to the enhanced adsorption on edge sites and the possible contribution from interlayer anion exchanges. The work reported here will

  9. Synthesis, characterization, and controlled release anticorrosion behavior of benzoate intercalated Zn-Al layered double hydroxides

    SciTech Connect

    Wang, Yi; Zhang, Dun

    2011-11-15

    Graphical abstract: The benzoate anion released from Zn-Al LDHs provides a more effective long-term protection against corrosion of Q235 carbon steel in 3.5% NaCl solution. Highlights: {yields} A benzoate anion corrosion inhibitor intercalated Zn-Al layered double hydroxides (LDHs) has been assembled by coprecipitation method. {yields} The kinetic simulation indicates that the ion-exchange one is responsible for the release process and the diffusion through particle is the rate limiting step. {yields} A significant reduction of the corrosion rate is observed when the LDH nanohybrid is present in the corrosive media. -- Abstract: Corrosion inhibitor-inorganic clay composite including benzoate anion intercalated Zn-Al layered double hydroxides (LDHs) are assembled by coprecipitation. Powder X-ray diffraction (XRD) and Fourier transform infrared (FT-IR) spectrum analyses indicate that the benzoate anion is successfully intercalated into the LDH interlayer and the benzene planes are vertically bilayer-positioned as a quasi-guest ion-pair form in the gallery space. Kinetic simulation for the release data, XRD and FT-IR analyses of samples recovered from the release medium indicate that ion-exchange is responsible for the release process and diffusion through the particle is also indicated to be the rate-limiting step. The anticorrosion capabilities of LDHs loaded with corrosion inhibitor toward Q235 carbon steel are analyzed by polarization curve and electrochemical impedance spectroscopy methods. Significant reduction of corrosion rate is observed when the LDH nanohybrid is present in the corrosive medium. This hybrid material may potentially be applied as a nanocontainer in self-healing coatings.

  10. Hierarchical Ni-Co layered double hydroxide nanosheets entrapped on conductive textile fibers: a cost-effective and flexible electrode for high-performance pseudocapacitors.

    PubMed

    Nagaraju, Goli; Raju, G Seeta Rama; Ko, Yeong Hwan; Yu, Jae Su

    2016-01-14

    Hierarchical three-dimensional (3D) porous nanonetworks of nickel-cobalt layered double hydroxide (Ni-Co LDH) nanosheets (NSs) are grown and decorated on flexible conductive textile substrate (CTs) via a simple two-electrode system based electrochemical deposition (ED) method. By applying a proper external cathodic voltage of -1.2 V for 15 min, the Ni-Co LDH NSs are densely deposited over the entire surface of the CTs with good adhesion. The flexible Ni-Co LDH NSs on CTs (Ni-Co LDH NSs/CTs) architecture with high porosity facilitates enhanced electrochemical performance in 1 M KOH electrolyte solution. The effect of growth concentration and external cathodic voltage on the electrochemical properties of Ni-Co LDH NSs/CTs is also investigated. The Ni10Co5 LDH NSs/CTs electrode exhibits a high specific capacitance of 2105 F g(-1) at a current density of 2 A g(-1) as well as an excellent cyclic stability as a pseudocapacitive electrode due to the advantageous properties of 3D interconnected porous frameworks of Ni10Co5 LDH NSs/CTs. This facile fabrication of bimetallic hydroxide nanostructures on CTs can provide a promising electrode for low-cost energy storage device applications. PMID:26450829

  11. Interlayer intercalation and arrangement of 2-mercaptobenzothiazolate and 1,2,3-benzotriazolate anions in layered double hydroxides: In situ X-ray diffraction study

    NASA Astrophysics Data System (ADS)

    Serdechnova, Maria; Salak, Andrei N.; Barbosa, Filipe S.; Vieira, Daniel E. L.; Tedim, João; Zheludkevich, Mikhail L.; Ferreira, Mário G. S.

    2016-01-01

    2-mercaptobenzothiazole (MBT) and 1,2,3-benzotriazole (BTA) are very promising inhibitors for the corrosion protection of aluminum alloys. These inhibitors can be incorporated in protective coatings in the form of anions intercalated into interlayers of layered double hydroxides (LDHs). Capacity and performance of such LDH-nanocontainers depend on the arrangement of the anions in their interlayers. In this work, intercalation of MBT- and BTA- into Mg-Al-NO3 and Zn-Al-NO3 LDHs were studied in detail using X-ray diffraction (XRD) methods including in situ XRD. The nitrate-to-MBT(BTA) anion exchange is much faster than considered previously. Well-formed Mg-Al-MBT, Zn-Al-MBT, Mg-Al-BTA LDHs were obtained after a 20-min exchange reaction at pH 11.5 at room temperature. It was demonstrated that Zn-Al-BTA LDH cannot be obtained under the same conditions due to the reaction between BTA and the Zn-Al hydroxide layers. Substitution of nitrates by organic anions occurs with the participation of hydroxide anions. Although no intermediate LDH phase intercalated with the combination of NO3 - and OH- appears, formation of the LDH-MBT and LDH-BTA phases results also in appearance of an LDH phase intercalated with OH- at the final stage of the anion exchange. In the LDH interlayer, MBT- and BTA- form a double layer in which these species have a tilted orientation against the layer plane (herringbone-like arrangement). Such an arrangement meets the LDH layer-interlayer electroneutrality and matches well with the observed values of the layer-interlayer distance.

  12. Thermal decomposition behavior of Cu–Al layered double hydroxide, and ethylenediaminetetraacetate-intercalated Cu–Al layered double hydroxide reconstructed from Cu–Al oxide for uptake of Y{sup 3+} from aqueous solution

    SciTech Connect

    Kameda, Tomohito; Hoshi, Kazuaki; Yoshioka, Toshiaki

    2012-12-15

    Graphical abstract: Display Omitted Highlights: ► Decomposition of CO{sub 3}·Cu–Al LDH occurred in four stages. ► The edta·Cu–Al LDH was found to take up Y{sup 3+} in aqueous solution. ► The edta·Cu–Al LDH could selectively take up rare earth ions from a mixed solution. -- Abstract: CO{sub 3}{sup 2−}-intercalated Cu–Al layered double hydroxide (CO{sub 3}·Cu–Al LDH) was calcined to yield Cu–Al oxide, and then ethylenediaminetetraacetate-intercalated Cu–Al LDH (edta·Cu–Al LDH) was prepared by reconstructing Cu–Al oxide in edta solution. Decomposition of CO{sub 3}·Cu–Al LDH occurred in four stages. The production of Cu–Al oxide was caused by the thermal decomposition of CO{sub 3}·Cu–Al LDH until the third stage. The first stage was the elimination of adsorbed surface water and interlayer water in CO{sub 3}·Cu–Al LDH. The second and third stages were the dehydroxylation of the brucite-like octahedral layers and the elimination of CO{sub 3}{sup 2−} intercalated in the interlayers. The edta·Cu–Al LDH was found to take up Y{sup 3+} in aqueous solution. The uptake of Y{sup 3+} was caused not only by the chelating function of Hedta{sup 3−} in the interlayer but also by the chemical behavior of Cu–Al LDH itself. The edta·Cu–Al LDH was found to selectively take up rare earth ions from a mixed solution. The degree of uptake was high, in the order Sc{sup 3+} > Y{sup 3+} > La{sup 3+} for all time durations, which was attributable to differences among the stabilities of Sc(edta){sup −}, Y(edta){sup −} and La(edta){sup −}.

  13. Dependence of bonding interactions in Layered Double Hydroxides on metal cation chemistry

    NASA Astrophysics Data System (ADS)

    Shamim, Mostofa; Dana, Kausik

    2016-12-01

    The evolution of various Infrared bands of Layered Double Hydroxides (LDH) with variable Zn:Al ratio was analyzed to correlate it with the changes in octahedral metal cation chemistry, interlayer carbonate anion and hydroxyl content of LDH. The synthesized phase-pure LDHs were crystallized as hexagonal 2H polytype with a Manasseite structure. The broad and asymmetric hydroxyl stretching region (2400-4000 cm-1) can be deconvoluted into four different bands. With increase in Zn2+:Al3+ metal ratio, the peak position of stretching frequencies of Al3+sbnd OH and carbonate-bridged hydroxyl (water) decrease almost linearly. Individual band's peak position and area under the curve have been successfully correlated with the carbonate and hydroxyl content of LDH. Due to lowering of symmetry of the carbonate anion, the IR-inactive peak νCsbnd O, symm at 1064 cm-1 becomes IR active. The peak position of metal-oxygen bands and carbonate bending modes are practically unaffected by the Zn2+:Al3+ ratio but the area under the individual M-O bands shows a direct correlation.

  14. Methotrexatum intercalated layered double hydroxides: statistical design, mechanism explore and bioassay study.

    PubMed

    Wang, Xiao-Feng; Liu, Su-Qing; Li, Shu-Ping

    2015-04-01

    A series of methotrexatum intercalated layered double hydroxide (MTX/LDH for short) hybrids have been synthesized by a mechanochemical-hydrothermal method, the statistical experiments are planned and conducted to find out the critical factor influencing the physicochemical properties. Four variables, i.e., addition of NaOH solution, grinding duration, hydrothermal temperature and time, are chosen to play as the examined factors in the orthogonal design. Furthermore, three respective levels, i.e., high, medium and low levels, are conducted in the design. The resulting hybrids are then characterized by X-ray diffraction (XRD) patterns, transmission electron microscope (TEM) graphs and Zeta potentials. XRD diffractions indicate that MTX anions have been successfully intercalated into LDH interlayers and the amount of NaOH solution can change the gallery height greatly. The information from TEM graphs and Zeta potentials state that the increase of alkali solution gives rise to regular morphology and the increase of Zeta potentials. As a result of the statistical analysis, addition of alkali solution is the major factor affecting the morphology and drug-loading capacity. At last, the mechanism of particle growth is explored emphatically, and the anticancer efficacy of some MTX/LDH hybrids is estimated by MTT assay on A549 cells as well. PMID:25686957

  15. Bone cement/layered double hydroxide nanocomposites as potential biomaterials for joint implant.

    PubMed

    Kapusetti, Govinda; Misra, Nira; Singh, Vakil; Kushwaha, R K; Maiti, Pralay

    2012-12-01

    Poly(methyl methacrylate)-based bone cement and layered double hydroxide (LDH) nanocomposites have been used as a grouting material for total joint arthroplasty. Few weight percentage of nanoLDH was uniformly dispersed in the bone cement matrix to have adequate interaction with matrix polymer. Mechanical strength, stiffness, toughness, and fatigue resistance of the nanocomposites are found to be higher than that of pure bone cement. Nanocomposites are thermally stable as compared to pristine bone cement. Direct mixing of the nanoLDH without any organic solvent makes these nanocomposites biocompatible. Biocompatibility was evaluated and compared with that of commercial bone cement by measuring hydrophilic nature, hemolysis assay, thrombosis assay, and deposition of apatite in simulated body fluid immersion. Finally, the viability of human osteoblast cells on the above developed nanocomposites was testified for actual biocompatibility. The experiment showed better cell growth in nanocomposites as compared to pure bone cement. Thus, these nanocomposites are found to be better grouting material than bone cement. PMID:22733710

  16. Optimization of UV absorptivity of layered double hydroxide by intercalating organic UV-absorbent molecules.

    PubMed

    Mohsin, Sumaiyah Megat Nabil; Hussein, Mohd Zobir; Sarijo, Siti Halimah; Fakurazi, Sharida; Arulselvan, Palanisamy; Taufiq-Yap, Yun Hin

    2014-08-01

    Intercalation of Zn/Al layered double hydroxide (LDH) with benzophenone 9 (B9), a strong ultraviolet (UV) absorber, had been carried out by two different routes; co-precipitation and ion exchange method. Powder X-ray diffraction (PXRD) patterns of co-precipitated (ZB9C) and ion exchanged product (ZB91) showed basal spacing of 15.9 angstrom and 16.6 angstrom, respectively, as a result of the intercalation of B9 anions into the lamellae spaces of LDH. Intercalation was further confirmed by Fourier transform infrared spectra (FTIR), carbon, hydrogen, nitrogen and sulfur (CHNS) and thermogravimetric and differential thermogravimetric (TGA/DTG) studies. UV-vis absorption properties of the nanocomposite was investigated with diffuse reflectance UV-visible spectrometer and showed broader UV absorption range. Furthermore, stability of sunscreen molecules in LDH interlayer space was tested in deionized water, artificial sea water and skin pH condition to show slow deintercalation and high retention in host. Cytotoxicity study of the synthesized nanocomposites on human dermal fibroblast (HDF) cells shows no significant cytotoxicity after 24 h exposure for test concentrations up to 25 microg/mL. PMID:25016649

  17. Nickel-cobalt layered double hydroxide nanosheets as high-performance electrocatalyst for oxygen evolution reaction

    NASA Astrophysics Data System (ADS)

    Jiang, Jing; Zhang, Ailing; Li, Lili; Ai, Lunhong

    2015-03-01

    Developing the first-row transition-metal-based oxygen evolution reaction (OER) catalysts with highly efficient electrocatalytic activity to replace precious catalysts, such as RuO2 and IrO2 have recently attracted considerable attention because of their earth abundant nature, low cost, environmentally friendly, multiple valence state and high theoretical activity. In this work, an advanced integrated electrode for high-performance electrochemical water oxidation has been designed and fabricated by directly growing binary nickel-cobalt layered double hydroxide (NiCo-LDH) nanosheet arrays on nickel foam. Such economical, earth abundant NiCo-LDH nanosheets show excellent OER activity in alkaline medium with an onset overpotential as low as 290 mV, large anodic current density and excellent durability, which makes them comparable to the most active RuO2 catalyst and better than the Pt/C catalyst. The outstanding OER activity of the NiCo-LDH nanosheets can be attributed to their intrinsic layered structure, interconnected nanoarray configuration and unique redox characteristics.

  18. Photocatalytic property and structural stability of CuAl-based layered double hydroxides

    NASA Astrophysics Data System (ADS)

    Lv, Ming; Liu, Haiqiang

    2015-07-01

    Three types of CuMAl layered double hydroxides (LDHs, M=Mg, Zn, Ni) were successfully synthesized by coprecipitation. Powder X-ray diffraction (XRD), inductively coupled plasma atomic emission spectrometry (ICP-AES) and UV-Vis diffuse reflectance spectrum (UV-vis) were used to confirm the formation of as-synthesized solids with good crystal structure. The photocatalytic activity of those LDH materials for CO2 reduction under visible light was investigated. The experimental results show that CuNiAl-LDHs with narrowest band gap and largest surface areas behave highest efficiency for methanol generation under visible light compared with CuMgAl-LDHs and CuZnAl-LDHs. The CuNiAL-LDH showed high yield for methanol production i.e. 0.210 mmol/g h, which was high efficient. In addition, the influence of the different M2+ on the structures and stability of the CuMAl-LDHs was also investigated by analyzing the geometric parameters, electronic arrangement, charge populations, hydrogen-bonding, and binding energies by density functional theory (DFT) analysis. The theoretical calculation results show that the chemical stability of LDH materials followed the order of CuMgAl-LDHs>CuZnAl-LDHs>CuNiAl-LDHs, which is just opposite with the photocatalytic activity and band gaps of three materials.

  19. Optimized immobilization of transketolase from E. coli in MgAl-layered double hydroxides.

    PubMed

    Touisni, Nadia; Charmantray, Franck; Helaine, Virgil; Forano, Claude; Hecquet, Laurence; Mousty, Christine

    2013-12-01

    Immobilization of TK from Escherichia coli (TKec) on MgAl-NO3 layered double hydroxides (LDH) was carried out by two processes: adsorption and coprecipitation. As a comparison, the adsorption method was realized either at pH 7.5 in buffered solutions (MOPS and Gly-Gly) or in pure water. For the coprecipitation method, the formation of the inorganic LDH support was realized directly in the presence of TKec solubilized in Gly-Gly. The prepared biohybrids, called respectively TKec@LDHads and TKec@LDHcop, were characterized by powder X-ray diffraction, FTIR spectroscopy in comparison with TKec free reference products, i.e. MgAl-NO3, MgAl-Gly-Gly. The enzymatic activities of the various TKec@LDH biohybrids as well as their stabilities over time were investigated by UV-vis assay. A maximum of activity (12 U/mg of solid) was reached for TKec@MgAl-Gly-Gly biohybrid prepared by coprecipitation. Finally, thin films were prepared through a one-step deposition on a polished support. The enzymatic activity of the resulting TKec@MgAl-Gly-Glycop film was tested over four recycling processes with a reproducible activity of 2.7 U/mg cm(2). PMID:24055860

  20. Layered double hydroxides as supports for intercalation and sustained release of antihypertensive drugs

    NASA Astrophysics Data System (ADS)

    Xia, Sheng-Jie; Ni, Zhe-Ming; Xu, Qian; Hu, Bao-Xiang; Hu, Jun

    2008-10-01

    Zn/Al layered double hydroxides (LDHs) were intercalated with the anionic antihypertensive drugs Enalpril, Lisinopril, Captopril and Ramipril by using coprecipitation or ion-exchange technique. TG-MS analyses suggested that the thermal stability of Ena -, Lis - (arranged with monolayer, resulted from X-ray diffraction (XRD) and Fourier transform infrared spectra (FT-IR) analysis was enhanced much more than Cap - and Ram - (arranged with bilayer). The release studies show that the release rate of all samples markedly decreased in both pH 4.25 and 7.45. However, the release time of Ena -, Lis - were much longer compared with Cap -, Ram - in both pH 4.25 and 7.45, it is possible that the intercalated guests, arranged with monolayer in the interlayer, show lesser repulsive force and strong affinity with the LDH layers. And the release data followed both the Higuchi-square-root law and the first-order equation well. Based on the analysis of batch release, intercalated structural models as well as the TG-DTA results, we conclude that for drug-LDH, stronger the affinity between intercalated anions and the layers is, better the thermal property and the stability to the acid attack of drug-LDH, and the intercalated anions are easier apt to monolayer arrangement within the interlayer, were presented.

  1. Evidences for decarbonation and exfoliation of layered double hydroxide in N,N-dimethylformamide-ethanol solvent mixture

    SciTech Connect

    Gordijo, Claudia R.; Leopoldo Constantino, Vera R.; Oliveira Silva, Denise de

    2007-07-15

    The behavior of a Hydrotalcite-like material (carbonate-containing Mg,Al-layered double hydroxide) in N,N-dimethylformamide (DMF)-ethanol mixture, at ambient temperature, has been investigated. The releasing of CO{sub 2} and production of a formate-containing material occurred mainly for 1:1 (v/v) solvent mixture. Decarbonation of Hydrotalcite is promoted by DMF hydrolysis followed by neutralization of brucite-like layers through HCOO{sup -} intercalation. Translucent colloidal dispersion of LDH nanoparticles from the formate-containing phase was characterized by transmission electron (TEM) and atomic force (AFM) microscopies. The absence of (00l) reflection at X-ray diffraction (XRD) pattern for dried colloidal dispersion indicated delamination of Hydrotalcite. The restacked sample exhibited broad reflections and typical hydroxide ordered layers non-basal (110) diffraction peaks. A LDH-HCOO{sup -} material was also prepared and characterized by FTIR and FT-Raman spectroscopies. Decarbonation and exfoliation of Hydrotalcite in N,N-dimethylformamide-ethanol mixed solvent provide an interesting method for preparation of new intercalated LDH materials. - Graphical abstract: Hydrotalcite suspended in 1:1 (v/v) N,N-dimethylformamide-ethanol solvent mixture, at ambient temperature, undergoes decarbonation and exfoliation. The process is promoted by DMF hydrolysis. Restacking of LDH layers is achieved by evaporating the solvent.

  2. Magnesium-containing layered double hydroxides as orthopaedic implant coating materials--An in vitro and in vivo study.

    PubMed

    Weizbauer, Andreas; Kieke, Marc; Rahim, Muhammad Imran; Angrisani, Gian Luigi; Willbold, Elmar; Diekmann, Julia; Flörkemeier, Thilo; Windhagen, Henning; Müller, Peter Paul; Behrens, Peter; Budde, Stefan

    2016-04-01

    The total hip arthroplasty is one of the most common artificial joint replacement procedures. Several different surface coatings have been shown to improve implant fixation by facilitating bone ingrowth and consequently enhancing the longevity of uncemented orthopaedic hip prostheses. In the present study, two different layered double hydroxides (LDHs), Mg-Fe- and Mg-Al-LDH, were investigated as potential magnesium (Mg)-containing coating materials for orthopaedic applications in comparison to Mg hydroxide (Mg(OH)2). In vitro direct cell compatibility tests were carried out using the murine fibroblast cell line NIH 3T3 and the mouse osteosarcoma cell line MG 63. The host response of bone tissue was evaluated in in vivo experiments with nine rabbits. Two cylindrical pellets (3 × 3 mm) were implanted into each femoral condyle of the left hind leg. The samples were analyzed histologically and with μ-computed tomography (μ-CT) 6 weeks after surgery. An in vitro cytotoxicity test determined that more cells grew on the LDH pellets than on the Mg(OH)2-pellets. The pH value and the Mg(2+) content of the cell culture media were increased after incubation of the cells on the degradable samples. The in vivo tests demonstrated the formation of fibrous capsules around Mg(OH)2 and Mg-Fe-LDH. In contrast, the host response of the Mg-Al-LDH samples indicated that this Mg-containing biomaterial is a potential candidate for implant coating. PMID:25939995

  3. Synthesis and characterization of metal (Core) - layered double hydroxide (Shell) nanostructures

    NASA Astrophysics Data System (ADS)

    Noh, Woo C.

    Layered double hydroxides (LDH) which belong to a class of inorganic ceramic layered materials have been studied since the mid-19th century for a variety of applications including catalysis, anion exchange, adsorbents and antacid, but more recently as a potential drug and gene delivery platform. Drug delivery platforms based on nano-sized geometries are nanovectors which promise a revolutionary impact on the therapy and imaging of various types of cancers and diseases. To date, various polymeric platforms have been the focus of intense research, but the development of inorganic, bio-hybrid nanoparticles for therapeutics and molecular imaging are at a stage of infancy. The hybridization of LDH with bioactive agents or the fabrication of metal (Core)---LDH (Shell) nanostructures could have many beneficial effects including multimodality, active targetability, and efficacy. For example, Core---Shell nanostructures may be designed to have a high scattering optical cross-section for imaging, but may also be tailored to strongly absorb near infrared (NIR) light for hyperthermic ablation. The central theme of this thesis was to demonstrate proof-of-concept of spherical silver and gold metal (Core)---LDH (Shell) nanostructures that have uniform size distribution and are agglomeration free. The effects of processing parameters on the characteristics of LDH as well as LDH-coated spherical metal (Ag, Au) nanoparticles have been evaluated using X-ray Diffraction, Dynamic Light Scattering, Scanning Electron Microscopy, Transmission Electron Microscopy, Rutherford Backscattering Spectrometry, and Inductively Coupled Plasma Emission Spectrometry to arrive at appropriate process windows. The core---shell nanostructures were also characterized for their optical properties in the ultra---violet---visible region, and the data were compared with simulated data, computed by using a quasi static model from Mie scattering theory. Moreover, in order to achieve a strong plasmon resonance

  4. 13C nuclear magnetic resonance analysis of glucose and citrate end products in an ldhL-ldhD double-knockout strain of Lactobacillus plantarum.

    PubMed Central

    Ferain, T; Schanck, A N; Delcour, J

    1996-01-01

    We have examined the metabolic consequences of knocking out the two ldh genes in Lactobacillus plantarum using 13C nuclear magnetic resonance. Unlike its wild-type isogenic progenitor, which produced lactate as the major metabolite under all conditions tested, ldh null strain TF103 mainly produced acetoin. A variety of secondary end products were also found, including organic acids (acetate, succinate, pyruvate, and lactate), ethanol, 2,3-butanediol, and mannitol. PMID:8955418

  5. 3D-architectured nickel-cobalt-manganese layered double hydroxide/reduced graphene oxide composite for high-performance supercapacitor

    NASA Astrophysics Data System (ADS)

    Li, M.; Cheng, J. P.; Liu, F.; Zhang, X. B.

    2015-11-01

    Pure flower-like NiCoMn layered double hydroxide (LDH) and 3D-architectured NiCoMn LDH/reduced graphene oxide (rGO) composite are fabricated by a solution method. The NiCoMn hydroxide nanoflakes are tightly deposited on the surface of rGO. Electrochemical measurements prove that rGO can greatly improve its capacitive performances, compared with the pure counterpart. A high-specific capacitance of 912 F g-1, high-rate capability and long cycle life are achieved for the composite. A NiCoMn LDH/rGO//activated carbon hybrid capacitor is also fabricated. It possesses a high-specific capacitance of 206 F g-1 and an energy density of 92.8 W h kg-1 in 1.8 V.

  6. Layered double hydroxides as effective carrier for anticancer drugs and tailoring of release rate through interlayer anions.

    PubMed

    Senapati, Sudipta; Thakur, Ravi; Verma, Shiv Prakash; Duggal, Shivali; Mishra, Durga Prasad; Das, Parimal; Shripathi, T; Kumar, Mohan; Rana, Dipak; Maiti, Pralay

    2016-02-28

    Hydrophobic anticancer drug, raloxifene hydrochloride (RH) is intercalated into a series of magnesium aluminum layered double hydroxides (LDHs) with various charge density anions through ion exchange technique for controlled drug delivery. The particle nature of the LDH in presence of drug is determined through electron microscopy and surface morphology. The release of drug from the RH intercalated LDHs was made very fast or sustained by altering the exchangeable anions followed by the modified Freundlich and parabolic diffusion models. The drug release rate is explained from the interactions between the drug and LDHs along with order-disorder structure of drug intercalated LDHs. Nitrate bound LDH exhibits greater interaction with drug and sustained drug delivery against the loosely interacted phosphate bound LDH-drug, which shows fast release. Cell viability through MTT assay suggests drug intercalated LDHs as better drug delivery vehicle for cancer cell line against poor bioavailability of the pure drug. In vivo study with mice indicates the differential tumor healing which becomes fast for greater drug release system but the body weight index clearly hints at damaged organ in the case of fast release system. Histopathological experiment confirms the damaged liver of the mice treated either with pure drug or phosphate bound LDH-drug, fast release system, vis-à-vis normal liver cell morphology for sluggish drug release system with steady healing rate of tumor. These observations clearly demonstrate that nitrate bound LDH nanoparticle is a potential drug delivery vehicle for anticancer drugs without any side effect. PMID:26774219

  7. Synthesis and selective IR absorption properties of iminodiacetic-acid intercalated MgAl-layered double hydroxide

    NASA Astrophysics Data System (ADS)

    Wang, Lijing; Xu, Xiangyu; Evans, David G.; Duan, Xue; Li, Dianqing

    2010-05-01

    An MgAl-NO 3-layered double hydroxide (LDH) precursor has been prepared by a method involving separate nucleation and aging steps (SNAS). Reaction with iminodiacetic acid (IDA) under weakly acidic conditions led to the replacement of the interlayer nitrate anions by iminodiacetic acid anions. The product was characterized by XRD, FT-IR, TG-DTA, ICP, elemental analysis and SEM. The results show that the original interlayer nitrate anions of LDHs precursor were replaced by iminodiacetic acid anions and that the resulting intercalation product MgAl-IDA-LDH has an ordered crystalline structure. MgAl-IDA-LDH was mixed with low density polyethylene (LDPE) using a masterbatch method. LDPE films filled with MgAl-IDA-LDH showed a higher mid to far infrared absorption than films filled with MgAl-CO 3-LDH in the 7-25 μm range, particularly in the key 9-11 μm range required for application in agricultural plastic films.

  8. Electrochemical sensor for bisphenol A based on ionic liquid functionalized Zn-Al layered double hydroxide modified electrode.

    PubMed

    Zhan, Tianrong; Song, Yang; Li, Xianjun; Hou, Wanguo

    2016-07-01

    The plate-like Zn-Al layered double hydroxide modified with 1-aminopropyl-3-methylimidzaolium tetrafluoroborate (named as ILs-LDH) was synthesized by coprecipitation method. Several techniques confirmed the layered structure of ILs-LDH with a disk-like morphology. A novel electrochemical sensor based on ILs-LDH modified glass carbon electrode (GCE) was developed for bisphenol A (BPA) determination. Experimental factors including modified content, pH, scan rate, accumulation time and potential had been carefully optimized. ILs-LDH/GCE performed the excellent electro-oxidation ability toward BPA with the more negative oxidation overpotential and larger peak current than bare GCE or LDH/GCE. Differential pulse voltammetry determination of BPA afforded a wider linear range from 0.02 to 3μM with the detection limit of 4.6nM (S/N=3). The fabricated sensor demonstrated an acceptable reproducibility, good stability and high sensitivity. The proposed method was successfully used to detect BPA in real water samples with satisfactory recovery ranging from 94.9% to 102.0%. PMID:27127064

  9. Corrosion resistance of Zn-Al layered double hydroxide/poly(lactic acid) composite coating on magnesium alloy AZ31

    NASA Astrophysics Data System (ADS)

    Zeng, Rong-Chang; Li, Xiao-Ting; Liu, Zhen-Guo; Zhang, Fen; Li, Shuo-Qi; Cui, Hong-Zhi

    2015-12-01

    A Zn-Al layered double hydroxide (ZnAl-LDH) coating consisted of uniform hexagonal nano-plates was firstly synthesized by co-precipitation and hydrothermal treatment on the AZ31 alloy, and then a poly(lactic acid) (PLA) coating was sealed on the top layer of the ZnAl-LDH coating using vacuum freeze-drying. The characteristics of the ZnAl-LDH/PLA composite coatings were investigated by means of XRD, SEM, FTIR and EDS. The corrosion resistance of the coatings was assessed by potentiodynamic polarization and electrochemical impedance spectroscopy (EIS). The results showed that the ZnAl-LDH coating contained a compact inner layer and a porous outer layer, and the PLA coating with a strong adhesion to the porous outer layer can prolong the service life of the ZnAl-LDH coating. The excellent corrosion resistance of this composite coating can be attributable to its barrier function, ion-exchange and self-healing ability.

  10. Mg-Al and Zn-Fe layered double hydroxides used for organic species storage and controlled release.

    PubMed

    Seftel, E M; Cool, P; Lutic, D

    2013-12-01

    Layered double hydroxides (LDH) containing (Mg and Al) or (Zn and Fe) were prepared by coprecipitation at constant pH, using NaOH and urea as precipitation agents. The most pure LDH phase in the Zn/Fe system was obtained with urea and in Mg/Al system when using NaOH. The incorporation of phenyl-alanine (Phe) anions in the interlayer of the LDH was performed by direct coprecipitation, ionic exchange and structure reconstruction of the mixed oxide obtained by the calcination of the coprecipitated product at 400°C. The reconstruction method and the direct coprecipitation in a medium containing Phe in the initial mixture were less successful in terms of high yields of organic-mineral composite than the ionic exchange method. A spectacular change in sample morphology and yield in exchanged solid was noticed for the Zn3Fe sample obtained by ionic exchange for 6h with Phe solution. A delivery test in PBS of pH=7.4 showed the release of the Phe in several steps up to 25 h indicating different host-guest interactions between the Phe and the LDH matrix. This behavior makes the preparation useful to obtain late delivery drugs, by the incorporation of the anion inside the LDH layer. PMID:24094226

  11. In vitro antioxidant activity and in vivo antifatigue effect of layered double hydroxide nanoparticles as delivery vehicles for folic acid

    PubMed Central

    Qin, Lili; Wang, Wenrui; You, Songhui; Dong, Jingmei; Zhou, Yunhe; Wang, Jibing

    2014-01-01

    Folic acid antioxidants were successfully intercalated into layered double hydroxides (LDH) nanoparticles according to a previous method with minor modification. The resultant folic acid-LDH constructs were then characterized by X-ray powder diffraction and transmission electron microscopy. The in vitro antioxidant activities, cytotoxicity effect, and in vivo antifatigue were examined by a series of assays. The results showed that folic acid-LDH antioxidant system can scavenge 1,1-diphenyl-2-picrylhydrazyl and hydroxyl free radicals and chelate pro-oxidative Cu2+. The in vitro cytotoxicity assays indicated that folic acid-LDH antioxidant system had no significant cytotoxic effect or obvious toxicity to normal cells. It also prolonged the forced swimming time of the mice by 32% and 51% compared to folic acid and control groups, respectively. It had an obvious effect on decreasing the blood urea nitrogen and blood lactic acid, while increasing muscle and hepatic glycogen levels. Therefore, folic acid-LDH might be used as a novel antioxidant and antifatigue nutritional supplement. PMID:25506219

  12. Stimuli-responsive hybrid materials: breathing in magnetic layered double hydroxides induced by a thermoresponsive molecule

    SciTech Connect

    Abellán, Gonzalo; Jordá, Jose Luis; Atienzar, Pedro; Varela, María; Jaafar, Miriam; Gómez-Herrero, Julio; Zamora, Félix; Ribera, Antonio; García, Hermenegildo; Coronado, Eugenio

    2014-12-04

    In this study, a hybrid magnetic multilayer material of micrometric size, with highly crystalline hexagonal crystals consisting of CoAl–LDH ferromagnetic layers intercalated with thermoresponsive 4-(4 anilinophenylazo)benzenesulfonate (AO5) molecules diluted (ratio 9 : 1) with a flexible sodium dodecylsulphate (SDS) surfactant has been obtained. The resulting material exhibits thermochromism attributable to the isomerization between the azo (prevalent at room temperature) and the hydrazone (favoured at higher temperatures) tautomers, leading to a thermomechanical response. In fact, these crystals exhibited thermally induced motion triggering remarkable changes in the crystal morphology and volume. In situ variable temperature XRD of these thin hybrids shows that the reversible change into the two tautomers is reflected in a shift of the position of the diffraction peaks at high temperatures towards lower interlayer spacing for the hydrazone form, as well as a broadening of the peaks reflecting lower crystallinity and ordering due to non-uniform spacing between the layers. These structural variations between room temperature (basal spacing (BS) = 25.91 Å) and 100 °C (BS = 25.05 Å) are also reflected in the magnetic properties of the layered double hydroxide (LDH) due to the variation of the magnetic coupling between the layers. Finally and in conclusion, our study constitutes one of the few examples showing fully reversible thermo-responsive breathing in a 2D hybrid material. In addition, the magnetic response of the hybrid can be modulated due to the thermotropism of the organic component that, by influencing the distance and in-plane correlation of the inorganic LDH, modulates the magnetism of the CoAl–LDH sheets in a certain range.

  13. Nanometric dispersion of a Mg/Al layered double hydroxide into a chemically modified polycaprolactone.

    PubMed

    Mangiacapra, Pasqualina; Raimondo, Marialuigia; Tammaro, Loredana; Vittoria, Vittoria; Malinconico, Mario; Laurienzo, Paola

    2007-03-01

    Polycaprolactone (PCL) was chemically modified by grafting maleic anhydride on it, through a radical reaction induced by benzoyl peroxide as initiator. To improve the grafting degree, a second unsaturated comonomer such as glycidyl methacrylate (GMA) has been added, demonstrating a good reactivity in melt grafting without leading to long grafted chains. The quantitative determination of grafted maleic anhydride, performed by FTIR analysis, revealed a grafting weight percentage of 9.5 +/- 0.9, and the NMR characterization made it possible to propose a structure for the grafted polymer (PCLgMA). The modified polymer was analyzed by DSC and X-ray diffraction, showing a structural organization even better than that of the pristine polymer. An exchange reaction with a layered double hydroxide (LDH), hydrotalcite-like solid in the nitrate form, led to the disappearance of the crystalline basal peak of LDH in the X-ray diffractograms, suggesting a possible exfoliation of the inorganic sample. An oxidative etching on the composite surface followed by atomic force microscopy analysis made it possible to enlighten the lamellar structure in the pristine sample. In the composite sample, the well identifiable narrow fissures homogeneously distributed on the surface demonstrate that nanometer stacks of LDH sheets, embedded in a highly textured PCLgMA matrix, are present in the composite sample. The comparison of X-ray diffractograms and AFM analysis suggests either a partial exfoliation or an intercalation of the polymer in a lamellar texture with a basal spacing higher than 5 nm. In any case, the process of ionic exchange between nitrate LDH and PCLgMA led to the formation of nanocomposites, in which no large hydrotalcite aggregates are present. This is an interesting method to obtain a direct intercalation of the modified polymer into the inorganic solid with a simple ionic exchange reaction. PMID:17319719

  14. Stimuli-responsive hybrid materials: breathing in magnetic layered double hydroxides induced by a thermoresponsive molecule

    DOE PAGESBeta

    Abellán, Gonzalo; Jordá, Jose Luis; Atienzar, Pedro; Varela, María; Jaafar, Miriam; Gómez-Herrero, Julio; Zamora, Félix; Ribera, Antonio; García, Hermenegildo; Coronado, Eugenio

    2014-12-04

    In this study, a hybrid magnetic multilayer material of micrometric size, with highly crystalline hexagonal crystals consisting of CoAl–LDH ferromagnetic layers intercalated with thermoresponsive 4-(4 anilinophenylazo)benzenesulfonate (AO5) molecules diluted (ratio 9 : 1) with a flexible sodium dodecylsulphate (SDS) surfactant has been obtained. The resulting material exhibits thermochromism attributable to the isomerization between the azo (prevalent at room temperature) and the hydrazone (favoured at higher temperatures) tautomers, leading to a thermomechanical response. In fact, these crystals exhibited thermally induced motion triggering remarkable changes in the crystal morphology and volume. In situ variable temperature XRD of these thin hybrids shows thatmore » the reversible change into the two tautomers is reflected in a shift of the position of the diffraction peaks at high temperatures towards lower interlayer spacing for the hydrazone form, as well as a broadening of the peaks reflecting lower crystallinity and ordering due to non-uniform spacing between the layers. These structural variations between room temperature (basal spacing (BS) = 25.91 Å) and 100 °C (BS = 25.05 Å) are also reflected in the magnetic properties of the layered double hydroxide (LDH) due to the variation of the magnetic coupling between the layers. Finally and in conclusion, our study constitutes one of the few examples showing fully reversible thermo-responsive breathing in a 2D hybrid material. In addition, the magnetic response of the hybrid can be modulated due to the thermotropism of the organic component that, by influencing the distance and in-plane correlation of the inorganic LDH, modulates the magnetism of the CoAl–LDH sheets in a certain range.« less

  15. Synthesis and Characterization of Chitosan-Coated Near-Infrared (NIR) Layered Double Hydroxide-Indocyanine Green Nanocomposites for Potential Applications in Photodynamic Therapy.

    PubMed

    Wei, Pei-Ru; Kuthati, Yaswanth; Kankala, Ranjith Kumar; Lee, Chia-Hung

    2015-01-01

    We designed a study for photodynamic therapy (PDT) using chitosan coated Mg-Al layered double hydroxide (LDH) nanoparticles as the delivery system. A Food and Drug Administration (FDA) approved near-infrared (NIR) fluorescent dye, indocyanine green (ICG) with photoactive properties was intercalated into amine modified LDH interlayers by ion-exchange. The efficient positively charged polymer (chitosan (CS)) coating was achieved by the cross linkage using surface amine groups modified on the LDH nanoparticle surface with glutaraldehyde as a spacer. The unique hybridization of organic-inorganic nanocomposites rendered more effective and successful photodynamic therapy due to the photosensitizer stabilization in the interlayer of LDH, which prevents the leaching and metabolization of the photosensitizer in the physiological conditions. The results indicated that the polymer coating and the number of polymer coats have a significant impact on the photo-toxicity of the nano-composites. The double layer chitosan coated LDH-NH₂-ICG nanoparticles exhibited enhanced photo therapeutic effect compared with uncoated LDH-NH₂-ICG and single layer chitosan-coated LDH-NH₂-ICG due to the enhanced protection to photosensitizers against photo and thermal degradations. This new class of organic-inorganic hybrid nanocomposites can potentially serve as a platform for future non-invasive cancer diagnosis and therapy. PMID:26340627

  16. Utilization of Active Ni to Fabricate Pt-Ni Nanoframe/NiAl Layered Double Hydroxide Multifunctional Catalyst through In Situ Precipitation.

    PubMed

    Ren, Fumin; Wang, Zheng; Luo, Liangfeng; Lu, Haiyuan; Zhou, Gang; Huang, Weixin; Hong, Xun; Wu, Yuen; Li, Yadong

    2015-09-14

    Integration of different active sites into metallic catalysts, which may impart new properties and functionalities, is desirable yet challenging. Herein, a novel dealloying strategy is demonstrated to decorate nickel-aluminum layered double hydroxide (NiAl-LDH) onto a Pt-Ni alloy surface. The incorporation of chemical etching of Pt-Ni alloy and in situ precipitation of LDH are studied by joint experimental and theoretical efforts. The initial Ni-rich Pt-Ni octahedra transform by interior erosion into Pt3 Ni nanoframes with enlarged surface areas. Furthermore, owing to the basic active sites of the decorated LDH together with the metallic sites of Pt3 Ni, the resulting Pt-Ni nanoframe/NiAl-LDH composites exhibit excellent catalytic activity and selectivity in the dehydrogenation of benzylamine and hydrogenation of furfural. PMID:26241390

  17. Reduced graphene oxide/Ni(1-x)Co(x)Al-layered double hydroxide composites: preparation and high supercapacitor performance.

    PubMed

    Xu, Jie; Gai, Shili; He, Fei; Niu, Na; Gao, Peng; Chen, Yujin; Yang, Piaoping

    2014-08-14

    Reduced graphene oxide (rGO) sheet and ternary-component Ni(1-x)Co(x)Al-layered double hydroxide (Ni(1-x)Co(x)Al-LDH) hybrid composites with an interesting sandwich structure have been fabricated by an in situ growth route. The as-obtained composite displays a sandwich architecture constructed by the self-assembly of sheet-like LDH crystals on both sides of the rGO sheets. It was found that the Co content doped in Ni(1-x)Co(x)Al-LDH plays an important role in the shape and structure of the final products. When the Co doped content is 17%, the rGO/Ni(0.83)Co(0.17)Al-LDH has a high surface area (171.5 m(2) g(-1)) and exhibits a perfect sandwich structure. In addition, this structure and morphology is favorable for a supercapacitor electrode material with a high performance. The influence of cobalt content on the electrochemical behavior of rGO/Ni(1-x)Co(x)Al-LDH has been systematically studied. The results indicate that the rGO/Ni(0.83)Co(0.17)Al-LDH composite exhibits the highest electrochemical performance, with a specific capacitance of 1902 F g(-1) at 1 A g(-1), and an excellent cycling stability. The markedly improved electrochemical performance is superior to undoped rGO/NiAl-LDH and can be attributed to the enhanced conductivity achieved through cobalt doping. Such composites could be used as a type of potential energy storage/conversion material for supercapacitors. PMID:24950435

  18. Intercalation of methotrexatum into layered double hydroxides via exfoliation-reassembly process

    NASA Astrophysics Data System (ADS)

    Liu, Su-Qing; Li, Shu-Ping; Li, Xiao-Dong

    2015-03-01

    In this paper, the intercalation of methotrexatum (MTX) into layered double hydroxides (LDHs) via an exfoliation-reassembly process was reported and the resulting hybrids were then characterized by X-ray diffraction (XRD) patterns, Fourier transform infrared (FTIR) spectroscopy and atomic force microscopy (AFM) patterns etc. In the synthesis procedure, LDHs particles were firstly delaminated into well-dispersed 2D nanosheets in formamide by ultrasonic treatment at room temperature, and then the resulting LDH nanosheets were reassembled in MTX solution to form MTX intercalated LDH (MTX/LDHs) hybrids. AFM images showed that during the exfoliation process a large part of LDHs particles were delaminated into single and double brucite layers. XRD patterns and FTIR investigations manifested the successful intercalation of MTX anions into LDHs interlayers for the final samples. It was also found out that the drug-loading capacity of the hybrids increased with the concentrations of MTX solutions, while the morphology became even aggregated. At last, the cell cytotoxicity of the hybrids was estimated by MTT assays on the human lung cancer cells (A549), and the results stated that MTX/LDHs hybrids had effective suppress role on the proliferation of cancer cells.

  19. Novel inorganic host layered double hydroxides intercalated with guest organic inhibitors for anticorrosion applications.

    PubMed

    Poznyak, S K; Tedim, J; Rodrigues, L M; Salak, A N; Zheludkevich, M L; Dick, L F P; Ferreira, M G S

    2009-10-01

    Zn-Al and Mg-Al layered double hydroxides (LDHs) loaded with quinaldate and 2-mercaptobenzothiazolate anions were synthesized via anion-exchange reaction. The resulting compounds were characterized by X-ray diffraction, Fourier transform infrared spectroscopy, and scanning electron microscopy/energy-dispersive X-ray spectroscopy. Spectrophotometric measurements demonstrated that the release of organic anions from these LDHs into the bulk solution is triggered by the presence of chloride anions, evidencing the anion-exchange nature of this process. The anticorrosion capabilities of LDHs loaded with organic inhibitors toward the AA2024 aluminum alloy were analyzed by electrochemical impedance spectroscopy. A significant reduction of the corrosion rate is observed when the LDH nanopigments are present in the corrosive media. The mechanism by which the inhibiting anions can be released from the LDHs underlines the versatility of these environmentally friendly structures and their potential application as nanocontainers in self-healing coatings. PMID:20355873

  20. Structure and photoluminescence of Mg-Al-Eu ternary hydrotalcite-like layered double hydroxides

    SciTech Connect

    Chen Yufeng; Li Fei; Zhou Songhua; Wei Junchao; Dai Yanfeng; Chen Yiwang

    2010-09-15

    A series of Mg-Al-Eu ternary hydrotalcite-like layered double hydroxides (LDHs), with Eu/Al atomic ratios of {approx}0.06 and Mg/(Al+Eu) atomic ratios ranging from 1.3 to 4.0, were synthesized by a coprecipitation method. The Mg-Al-Eu ternary LDHs were investigated by various techniques. X-ray diffraction (XRD) results indicated that the crystallinity of the ternary LDHs was gradually improved with the increase of Mg{sup 2+}/(Al{sup 3+}+Eu{sup 3+}) molar ratio from 1.3/1 to 4/1, and all the samples were a single phase corresponding to LDH. The photoluminescent (PL) spectra of the ternary Mg-Al-Eu LDHs were described by the well-known {sup 5}D{sub 0}-{sup 7}F{sub J} transition (J=1, 2, 3, 4) of Eu{sup 3+} ions with the strongest emission for J=2, suggesting that the host LDH was favorable to the emissions of Eu{sup 3+} ions. The asymmetry parameter (R) relevant to {sup 5}D{sub 0}-{sup 7}F{sub J} transition (J=1, 2) dependant of the atomic ratios of Mg{sup 2+}/(Al{sup 3+}+Eu{sup 3+}) was discussed, and was consistent with the result of XRD. - Graphical abstract: A series of Mg-Al-Eu ternary hydrotalcite-like layered double hydroxides (LDHs), with Mg/(Al+Eu) atomic ratios ranging from 1.3/1, 2/1 3/1 to 4/1, were synthesized by a coprecipitation method. The photoluminescent spectra of the Mg-Al-Eu ternary LDHs are described by the well-known {sup 5}D{sub 0}-{sup 7}F{sub J} transition (J=1, 2, 3, 4) of Eu{sup 3+} ions with the strongest emission for J=2.

  1. Synthesis of Cd/(Al+Fe) layered double hydroxides and characterization of the calcination products

    SciTech Connect

    Perez, M.R.; Barriga, C.; Fernandez, J.M.; Rives, V.; Ulibarri, M.A.

    2007-12-15

    Layered double hydroxides (LDHs) containing Cd(II), Al(III), and Fe(III) in the brucite-like layers with different starting Fe/Al atomic ratios and with nitrate as counteranion have been prepared following the coprecipitation method at a constant pH value of 8. An additional Cd(II),Al(III)-LDH sample interlayered with hexacyanoferrate(III) ions has been prepared by ionic exchange at pH 9. The samples have been characterized by elemental chemical analysis, powder X-ray diffraction (PXRD), and FT-IR spectroscopy. Their thermal stability has been assessed by thermogravimetric and differential thermal analyses (TG-DTA) and mass spectrometric analysis of the evolved gases. The PXRD patterns of the solids calcined at 800 deg. C show diffraction lines corresponding to Cd(Al)O and spinel-type materials, which precise nature (CdAl{sub 2}O{sub 4}, Cd{sub 1-x}Fe{sub 2+x}O{sub 4}, or Cd{sub x}Fe{sub 2.66}O{sub 4}) depends on location and concentration of iron in the parent material or precursor. - Graphical abstract: Layered double hydroxides (LDHs) containing Cd(II), Al(III), and Fe(III) in the brucite-like layers with different starting Fe/Al atomic ratios and with nitrate as counteranion have been prepared following the coprecipitation method. An additional Cd(II),Al(III)-LDH sample interlayered with hexacyanoferrate(III) ions has been prepared by ionic exchange. Calcination at 800 deg. C shows diffraction lines corresponding to CdO and to spinel-type materials. SEM micrograph of sample CdAlFe-N-0.

  2. Tailoring surface properties and structure of layered double hydroxides using silanes with different number of functional groups

    SciTech Connect

    Tao, Qi; He, Hongping; Li, Tian; Frost, Ray L.; Zhang, Dan; He, Zisen

    2014-05-01

    Four silanes, trimethylchlorosilane (TMCS), dimethyldiethoxylsilane (DMDES), 3-aminopropyltriethoxysilane (APTES) and tetraethoxysilane (TEOS), were adopted to graft layered double hydroxides (LDH) via an induced hydrolysis silylation method (IHS). Fourier transform infrared spectra (FTIR) and {sup 29}Si MAS nuclear magnetic resonance spectra ({sup 29}Si MAS NMR) indicated that APTES and TEOS can be grafted onto LDH surfaces via condensation with hydroxyl groups of LDH, while TMCS and DMDES could only be adsorbed on the LDH surface with a small quantity. A combination of X-ray diffraction patterns (XRD) and {sup 29}Si MAS NMR spectra showed that silanes were exclusively present in the external surface and had little influence on the long range order of LDH. The surfactant intercalation experiment indicated that the adsorbed and/or grafted silane could not fix the interlamellar spacing of the LDH. However, they will form crosslink between the particles and affect the further surfactant intercalation in the silylated samples. The replacement of water by ethanol in the tactoids and/or aggregations and the polysiloxane oligomers formed during silylation procedure can dramatically increase the value of BET surface area (S{sub BET}) and total pore volumes (V{sub p}) of the products. - Graphical abstract: The replacement of water by ethanol in the tactoids and aggregations of LDHs, and the polysiloxane oligomers formed during silylation process can dramatically increase the BET surface area (S{sub BET}) and the total pore volume (V{sub p}) of the silylated products. - Highlights: • Silanes with multifunctional groups were grafted onto LDH surface in C{sub 2}H{sub 5}OH medium. • The number of hydrolysable groups in silanes affects the structure of grafted LDH. • Replacement of H{sub 2}O by C{sub 2}H{sub 5}OH in aggregations increases S{sub BET} and V{sub p} of grafted LDH. • Polysiloxane oligomers contribute to the increase of S{sub BET} and V{sub p} of grafted LDH.

  3. In situ oligomerization of 2-(thiophen-3-yl)acetate intercalated into Zn{sub 2}Al layered double hydroxide

    SciTech Connect

    Tronto, Jairo; Pinto, Frederico G.; Costa, Liovando M. da; Leroux, Fabrice; Dubois, Marc; Valim, João B.

    2015-01-15

    A layered double hydroxide (LDH) with cation composition Zn{sub 2}Al was intercalated with 2-(thiophen-3-yl)acetate (3-TA) monomers. To achieve in situ polymerization and/or oligomerization of the intercalated monomers, soft thermal treatments were carried out, and subsequent hybrid LDH materials were analyzed by means of several characterization techniques using powder X-ray diffraction (PXRD), Fourier transform infrared spectroscopy (FTIR), thermogravimetric analysis (TGA), {sup 13}C CP–MAS nuclear magnetic resonance (NMR), electron spin resonance (EPR), scanning electron microscopy (SEM), and transmission electron microscopy (TEM), inductively coupled plasma optical emission spectroscopy (ICP–OES), and elemental analysis. PXRD analysis suggested that the intercalated monomers formed a bilayer. Thermal treatment of the hybrid LDH assembly above 120 °C provokes partially the breakdown of the layered structure, generating the phase zincite. EPR results indicated that vicinal monomers (oligomerization) were bound to each other after hydrothermal or thermal treatment, leading to a polaron response characteristic of electron conductivity localized on a restricted number of thiophene-based monomer segments. Localized unpaired electrons exist in the material and interact with the {sup 27}Al nuclei of the LDH layers by superhyperfine coupling. These unpaired electrons also interact with the surface of ZnO (O{sup 2−} vacancies), formed during the thermal treatments. - Graphical abstract: We synthesized a layered double hydroxide (LDH) with cation composition Zn{sub 2}Al, intercalated with 2-(thiophen-3-yl)acetate (3-TA) monomers, by coprecipitation at constant pH. We thermally treated the material, to achieve in situ polymerization and/or oligomerization of the intercalated monomers. - Highlights: • A Zn{sub 2}Al–LDH was intercalated with 2-(thiophen-3-yl)acetate monomers. • To achieve in situ oligomerization of the monomers, thermal treatments were made.

  4. Mixed metal oxides for dye-sensitized solar cell using zinc titanium layered double hydroxide as precursor

    NASA Astrophysics Data System (ADS)

    Liu, Jianqiang; Qin, Yaowei; Zhang, Liangji; Xiao, Hongdi; Song, Jianye; Liu, Dehe; Leng, Mingzhe; Hou, Wanguo; Du, Na

    2013-12-01

    Mixed metal oxides (MMO) are always obtained from layered double hydroxide (LDH) by thermal decomposition. In the present work, a zinc titanium LDH with the zinc titanium molar ratio of 4.25 was prepared by urea method and ZnO-based mixed oxides were obtained by calcining at or over 500°C. The MMO was used as electrodes for dye sensitized solar cell (DSSC). The cells constructed by films of prepared composite materials using a N719 as dye were prepared. The efficiency values of these cells are 0.691%, 0.572% and 0.302% with MMO prepared at 500, 600 and 700°C, respectively.

  5. Effect of inorganic and organic ligands on the sorption/desorption of arsenate on/from Al-Mg and Fe-Mg layered double hydroxides.

    PubMed

    Caporale, A G; Pigna, M; Dynes, J J; Cozzolino, V; Zhu, J; Violante, A

    2011-12-30

    This paper describes the sorption of arsenate on Al-Mg and Fe-Mg layered double hydroxides as affected by pH and varying concentrations of inorganic and organic ligands, and the effect of residence time on the desorption of arsenate by ligands. The capacity of ligands to inhibit the fixation of arsenate followed the sequence: nitrateLDH and nitrateLDH. The inhibition of arsenate sorption increased by increasing the initial ligand concentration and was greater on Al-Mg-LDH than on Fe-Mg-LDH. The longer the arsenate residence time on the LDH surfaces the less effective the competing ligands were in desorbing arsenate from sorbents. A greater percentage of arsenate was removed by phosphate from Al-Mg-LDH than from Fe-Mg-LDH, due to the higher affinity of arsenate for iron than aluminum. PMID:22071258

  6. High-performance hybrid supercapacitor with 3D hierarchical porous flower-like layered double hydroxide grown on nickel foam as binder-free electrode

    NASA Astrophysics Data System (ADS)

    Zhang, Luojiang; Hui, Kwun Nam; San Hui, Kwan; Lee, Haiwon

    2016-06-01

    The synthesis of layered double hydroxide (LDH) as electroactive material has been well reported; however, fabricating an LDH electrode with excellent electrochemical performance at high current density remains a challenge. In this paper, we report a 3D hierarchical porous flower-like NiAl-LDH grown on nickel foam (NF) through a liquid-phase deposition method as a high-performance binder-free electrode for energy storage. With large ion-accessible surface area as well as efficient electron and ion transport pathways, the prepared LDH-NF electrode achieves high specific capacity (1250 C g-1 at 2 A g-1 and 401 C g-1 at 50 A g-1) after 5000 cycles of activation at 20 A g-1 and high cycling stability (76.7% retention after another 5000 cycles at 50 A g-1), which is higher than those of most previously reported NiAl-LDH-based materials. Moreover, a hybrid supercapacitor with LDH-NF as the positive electrode and porous graphene nanosheet coated on NF (GNS-NF) as the negative electrode, delivers high energy density (30.2 Wh kg-1 at a power density of 800 W kg-1) and long cycle life, which outperforms the other devices reported in the literature. This study shows that the prepared LDH-NF electrode offers great potential in energy storage device applications.

  7. A novel injectable thermoresponsive and cytocompatible gel of poly(N-isopropylacrylamide) with layered double hydroxides facilitates siRNA delivery into chondrocytes in 3D culture.

    PubMed

    Yang, Hsiao-yin; van Ee, Renz J; Timmer, Klaas; Craenmehr, Eric G M; Huang, Julie H; Öner, F Cumhur; Dhert, Wouter J A; Kragten, Angela H M; Willems, Nicole; Grinwis, Guy C M; Tryfonidou, Marianna A; Papen-Botterhuis, Nicole E; Creemers, Laura B

    2015-09-01

    Hybrid hydrogels composed of poly(N-isopropylacrylamide) (pNIPAAM) and layered double hydroxides (LDHs) are presented in this study as novel injectable and thermoresponsive materials for siRNA delivery, which could specifically target several negative regulators of tissue homeostasis in cartilaginous tissues. Effectiveness of siRNA transfection using pNIPAAM formulated with either MgAl-LDH or MgFe-LDH platelets was investigated using osteoarthritic chondrocytes. Glyceraldehyde-3-phosphate dehydrogenase (GAPDH) was used as an endogenous model gene to evaluate the extent of silencing. No significant adverse effects of pNIPAAM/LDH hydrogels on cell viability were noticed. Cellular uptake of fluorescently labeled siRNA was greatly enhanced (>75%) in pNIPAAM/LDH hydrogel constructs compared to alginate, hyaluronan and fibrin gels, and was absent in pNIPAAM hydrogel without LDH platelets. When using siRNA against GAPDH, 82-98% reduction of gene expression was found in both types of pNIPAAM/LDH hydrogel constructs after 6 days of culturing. In the pNIPAAM/MgAl-LDH hybrid hydrogel, 80-95% of GAPDH enzyme activity was reduced in parallel with gene. Our findings show that the combination of a cytocompatible hydrogel and therapeutic RNA oligonucleotides is feasible. Thus it might hold promise in treating degeneration of cartilaginous tissues by providing supporting scaffolds for cells and interference with locally produced degenerative factors. PMID:26022968

  8. Synthesis, anion exchange, and delamination of Co-Al layered double hydroxide: assembly of the exfoliated nanosheet/polyanion composite films and magneto-optical studies.

    PubMed

    Liu, Zhaoping; Ma, Renzhi; Osada, Minoru; Iyi, Nobuo; Ebina, Yasuo; Takada, Kazunori; Sasaki, Takayoshi

    2006-04-12

    This paper describes a systematic study on the synthesis, anion exchange, and delamination of Co-Al layered double hydroxide (LDH), with the aim of achieving fabrication and clarifying the properties of LDH nanosheet/polyanion composite films. Co-Al-CO3 LDH hexagonal platelets of 4 mum in lateral size were synthesized by the urea method under optimized reaction conditions. The as-prepared CO3(2-)-LDH was converted to Cl- -LDH by treating with a NaCl-HCl mixed solution, retaining its high crystallinity and hexagonal platelike morphology. LDHs intercalated with a variety of anions (such as NO3-, ClO4-, acetate, lactate, dodecyl sulfate, and oleate) were further prepared from Cl- -LDH via an anion-exchange process employing corresponding salts. Exchanged products in various anion forms were found to show different delamination behaviors in formamide. Among them, best results were observed for NO3- -LDH in terms of the exfoliating degree and the quality of the exfoliated nanosheets. The delamination gave a pink transparent suspension containing well-defined nanosheets with lateral sizes of up to 2 microm. The resulting nanosheets were assembled layer-by-layer with an anionic polymer, poly(sodium styrene 4-sulfonate) (PSS), onto quartz glass substrates to produce composite films. Magnetic circular dichroism (MCD) measurements revealed that the assembled multilayer films exhibited an interesting magneto-optical response. PMID:16594724

  9. Synthesis and reversible hydration behavior of the thiosulfate intercalated layered double hydroxide of Zn and Al

    SciTech Connect

    Radha, S.; Milius, Wolfgang; Breu, Josef; Kamath, P. Vishnu

    2013-08-15

    The thiosulfate-intercalated layered double hydroxide of Zn and Al undergoes reversible hydration with a variation in the relative humidity of the ambient. The hydrated and dehydrated phases, which represent the end members of the hydration cycle, both adopt the structure of the 3R{sub 1} polytype. In the intermediate range of relative humidity values (40–60%), the hydrated and dehydrated phases coexist. The end members of the hydration cycle adopt the structure of the same polytype, and vary only in their basal spacings. This points to the possibility that all the intermediate phases have a kinetic origin. - Graphical abstract: Basal spacing evolution of the thiosulfate ion intercalated [Zn–Al] LDH during one complete hydration–dehydration cycle as a function of relative humidity. Display Omitted - Highlights: • Thiosulfate intercalated [Zn–Al] LDHs were synthesized by co-precipitation. • The LDH exhibits reversible hydration with variation in humidity. • Both the end members of the hydration cycle adopt the same polytype structure. • The interstratified intermediates observed are kinetic in origin.

  10. Carboxylate-intercalated layered double hydroxides aged under microwave-hydrothermal treatment

    NASA Astrophysics Data System (ADS)

    Benito, P.; Labajos, F. M.; Mafra, L.; Rocha, J.; Rives, V.

    2009-01-01

    Carboxylate-intercalated (terephthalate, TA and oxalate, ox) layered double hydroxides (LDHs) are aged under a microwave-hydrothermal treatment. The influence of the nature of the interlayer anion during the ageing process is studied. Characterization results show that the microwave-hydrothermal method can be extended to synthesize LDHs with anions different than carbonate, like TA. LDH-TA compounds are stable under microwave irradiation for increasing periods of time and the solids show an improved order both in the layers and in the interlayer region as evidenced by powder X-ray diffraction (PXRD), 27Al MAS NMR and FT-IR spectroscopy. Furthermore, cleaning of the surface through removal of some organic species adsorbed on the surface of the particles also occurs during the microwave-hydrothermal treatment. Conversely, although the expected increase in crystallinity is observed in LDH-ox samples, the side-reaction between Al 3+ and ox is also enhanced under microwave irradiation, and a partial destruction of the structure takes place with an increase in the M 2+/M 3+ ratio and consequent modification of the cell parameters.

  11. Potential for Layered Double Hydroxides-Based, Innovative Drug Delivery Systems

    PubMed Central

    Zhang, Kai; Xu, Zhi Ping; Lu, Ji; Tang, Zhi Yong; Zhao, Hui Jun; Good, David A.; Wei, Ming Qian

    2014-01-01

    Layered Double Hydroxides (LDHs)-based drug delivery systems have, for many years, shown great promises for the delivery of chemical therapeutics and bioactive molecules to mammalian cells in vitro and in vivo. This system offers high efficiency and drug loading density, as well as excellent protection of loaded molecules from undesired degradation. Toxicological studies have also found LDHs to be biocompatible compared with other widely used nanoparticles, such as iron oxide, silica, and single-walled carbon nanotubes. A plethora of bio-molecules have been reported to either attach to the surface of or intercalate into LDH materials through co-precipitation or anion-exchange reaction, including amino acid and peptides, ATPs, vitamins, and even polysaccharides. Recently, LDHs have been used for gene delivery of small molecular nucleic acids, such as antisense, oligonucleotides, PCR fragments, siRNA molecules or sheared genomic DNA. These nano-medicines have been applied to target cells or organs in gene therapeutic approaches. This review summarizes current progress of the development of LDHs nanoparticle drug carriers for nucleotides, anti-inflammatory, anti-cancer drugs and recent LDH application in medical research. Ground breaking studies will be highlighted and an outlook of the possible future progress proposed. It is hoped that the layered inorganic material will open up new frontier of research, leading to new nano-drugs in clinical applications. PMID:24786098

  12. Bioactive Nanocomposite Poly (Ethylene Glycol) Hydrogels Crosslinked by Multifunctional Layered Double Hydroxides Nanocrosslinkers.

    PubMed

    Huang, Heqin; Xu, Jianbin; Wei, Kongchang; Xu, Yang J; Choi, Chun Kit K; Zhu, Meiling; Bian, Liming

    2016-07-01

    Poly (ethylene glycol) (PEG) based hydrogels have been widely used in many biomedical applications such as regenerative medicine due to their good biocompatibility and negligible immunogenicity. However, bioactivation of PEG hydrogels, such as conjugation of bioactive biomolecules, is usually necessary for cell-related applications. Such biofunctionalization of PEG hydrogels generally involves complicated and time-consuming bioconjugation procedures. Herein, we describe the facile preparation of bioactive nanocomposite PEG hydrogel crosslinked by the novel multifunctional nanocrosslinkers, namely polydopamine-coated layered double hydroxides (PD-LDHs). The catechol-rich PD-LDH nanosheets not only act as effective nanocrosslinkers reinforcing the mechanical strength of the hydrogel, but also afford the hydrogels with robust bioactivity and bioadhesion via the cortical-mediated couplings. The obtained nanocomposite PEG hydrogels with the multifunctional PD-LDH crosslinking domains show tunable mechanical properties, self-healing ability, and bioadhesion to biological tissues. Furthermore, these hydrogels also promote the sequestration of proteins and support the osteogenic differentiation of human mesenchymal stem cells without any further bio-functionalization. Such facile preparation of bioactive and bioadhesive PEG hydrogels have rarely been achieved and may open up a new avenue for the design of nanocomposite PEG hydrogels for biomedical applications. PMID:27061462

  13. Removal of Remazol Blue 19 from wastewater by zinc-aluminium-chloride-layered double hydroxides

    NASA Astrophysics Data System (ADS)

    Elkhattabi, El Hassan; Lakraimi, Mohamed; Badreddine, Mohamed; Legrouri, Ahmed; Cherkaoui, Omar; Berraho, Moha

    2013-06-01

    Layered double hydroxides (LDHs), also called anionic clays, consist of cationic brucite-like layers and exchangeable interlayer anions. These hydrotalcite-like compounds, with Zn and Al in the layers and chloride in the interlayer space, were prepared following the coprecipitation method at constant pH. The affinity of this material for Remazol Blue 19, RB19 [ 2- (3- (4- Amino- 9,10- dihydro- 3- sulpho- 9,10- dioxoanthracen- 4- yl) aminobenzenesulphonyl) vinyl) disodiumsulphate], was studied as a function of contact time, pH of the solutions LDH dose and the RB19/[Zn-Al-Cl] mass ratio. It was found that 48 h is enough time for the equilibrium state to be reached with maximum RB19 retention at pH of 9 for an LDH dose equal to 100 mg and with an RB19/[Zn-Al-Cl] mass ratio higher than 3. The adsorption isotherm, described by the Langmuir model, is of L-type. The results demonstrate that RB19 retention on LDHs occurs by adsorption on external surface when RB19/[Zn-Al-Cl] mass ratio is equal or <3 and by both adsorption and interlayer ion exchange for ratios higher than 3. A mechanism for removal of RB19 anion has been confirmed by X-ray diffraction, IR spectroscopy and TG analysis (TG and DTG curves).

  14. Synthesis, characterization, and controlled release antibacterial behavior of antibiotic intercalated Mg–Al layered double hydroxides

    SciTech Connect

    Wang, Yi; Zhang, Dun

    2012-11-15

    Graphical abstract: The antibiotic anion released from Mg–Al LDHs provides a controlled release antibacterial activity against the growth of Micrococcus lysodeikticus in 3.5% NaCl solution. Highlights: ► Antibiotic anion intercalated LDHs were synthesized and characterized. ► The ion-exchange one is responsible for the release process. ► The diffusion through particle is the release rate limiting step. ► LDHs loaded with antibiotic anion have high antibacterial capabilities. -- Abstract: Antibiotic–inorganic clay composites including four antibiotic anions, namely, benzoate (BZ), succinate (SU), benzylpenicillin (BP), and ticarcillin (TC) anions, intercalated Mg–Al layered double hydroxides (LDHs) were synthesized via ion-exchange. Powder X-ray diffraction and Fourier transform infrared spectrum analyses showed the successful intercalation of antibiotic anion into the LDH interlayer. BZ and BP anions were accommodated in the interlayer region as a bilayer, whereas SU and TC anions were intercalated in a monolayer arrangement. Kinetic simulation of the release data indicated that ion-exchange was responsible for the release process, and the diffusion through the particles was the rate-limiting step. The antibacterial capabilities of LDHs loaded with antibiotic anion toward Micrococcus lysodeikticus growth were analyzed using a turbidimetric method. Significant high inhibition rate was observed when LDH nanohybrid was introduced in 3.5% NaCl solution. Therefore, this hybrid material may be applied as nanocontainer in active antifouling coating for marine equipment.

  15. From spent Mg/Al layered double hydroxide to porous carbon materials.

    PubMed

    Laipan, Minwang; Zhu, Runliang; Chen, Qingze; Zhu, Jianxi; Xi, Yunfei; Ayoko, Godwin A; He, Hongping

    2015-12-30

    Adsorption has been considered as an efficient method for the treatment of dye effluents, but proper disposal of the spent adsorbents is still a challenge. This work attempts to provide a facile method to reutilize the spent Mg/Al layered double hydroxide (Mg/Al-LDH) after the adsorption of orange II (OII). Herein, the spent hybrid was carbonized under the protection of nitrogen, and then washed with acid to obtain porous carbon materials. Thermogravimetric analysis results suggested that the carbonization could be well achieved above 600°C, as mass loss of the spent hybrid gradually stabilized. Therefore, the carbonization process was carried out at 600, 800, and 1000°C, respectively. Scanning electron microscope showed that the obtained carbon materials possessed a crooked flaky morphology. Nitrogen adsorption-desorption results showed that the carbon materials had large BET surface area and pore volume, e.g., 1426 m(2)/g and 1.67 cm(3)/g for the sample carbonized at 800°C. Moreover, the pore structure and surface chemistry compositions were tunable, as they were sensitive to the temperature. Toluene adsorption results demonstrated that the carbon materials had high efficiency in toluene removal. This work provided a facile approach for synthesizing porous carbon materials using spent Mg/Al-LDH. PMID:26257095

  16. Simultaneous photooxidation and sorptive removal of As(III) by TiO2 supported layered double hydroxide.

    PubMed

    Lee, Sang-Ho; Kim, Kyoung-Woong; Choi, Heechul; Takahashi, Yoshio

    2015-09-15

    The present study focused on the enhanced removal of As(III) by the simultaneous photooxidation and removal process using TiO2 nanoparticles supported layered double hydroxide (TiO2/LDH). The TiO2/LDH nanocomposites were synthesized using a flocculation method, and nanosized (30-50 nm) TiO2 particles were well-distributed on the LDH surface. The XPS and DLS data revealed that the TiO2/LDH nanocomposites were both chemically and physically stable in the aquatic system. The optimum ratio of TiO2 was 20 wt.% and the calcination process of LDH enhanced the removal capacity of As(III) by the reconstruction process. In the kinetic removal experiment, UV irradiation improved the removal rate of As(III), based on the continuous conversion of As(III) to As(V), and that the removal rate was faster under alkaline conditions than acidic and neutral conditions due to the abundance of oxidants and negative charged As(III) species (pKa: 9.2). The main mechanism of As(III) photooxidation is the direct oxidation by [Formula: see text] , which is generated by supported TiO2 nanoparticles. X-ray near edge structure results also confirmed that the As(III) was completely oxidized to As(V). Consequently, the simultaneous photooxidation and removal process of As(III) by TiO2/LDH nanocomposites may be the effective removal option in As(III) contaminated water. PMID:26186550

  17. Strong interfacial attrition developed by oleate/layered double hydroxide nanoplatelets dispersed into poly(butylene succinate).

    PubMed

    Zhou, Qian; Verney, Vincent; Commereuc, Sophie; Chin, In-Joo; Leroux, Fabrice

    2010-09-01

    Poly(butylene succinate) (PBS) nanocomposite structure was studied as a function of the filler percentage loading. The resulting state of dispersion was evaluated by XRD and TEM, and the interfacial attrition between PBS chain and lamellar platelets by the melt rheological properties. Hybrid organic inorganic (O/I) layered double hydroxide (LDH) organo-modified by oleate anions was used as filler. It was found that the confinement supplied by the LDH framework forces the interleaved organic molecule to be more distant from each other than in the case of oleate salt, this having as an effect to decrease strongly the homonuclear intermolecular (1)H(1)H dipolar interaction. An additional consequence of this relatively free molecular rotation, affecting the (13)C CPMAS response as well, is to facilitate the delamination of the 2D-stacked layers during extrusion since an quasi-exfoliated PBS:Mg(2)Al/oleate structure is observed for filler loading lower than 5% w/w. This is in association to a non-linear viscoelasticity in the low-omega region and the observed shear-thinning tendency compares better than other PBS:silicate nanocomposite derivatives and is here explained by the presence of a percolated LDH nanoparticle network. Indeed the plastic deformation in the low-omega region is found to be restricted by well-dispersed LDH tactoids in association with a rather strong attrition phenomenon between tethered oleate anions and PBS chains. PMID:20605578

  18. Development of efficient electrocatalysts via molecular hybridization of NiMn layered double hydroxide nanosheets and graphene.

    PubMed

    Ma, Wei; Ma, Renzhi; Wu, Jinghua; Sun, Pengzhan; Liu, Xiaohe; Zhou, Kechao; Sasaki, Takayoshi

    2016-05-21

    Ni(2+)Mn(3+) layered double hydroxide (LDH) nanoplatelets have been hydrothermally synthesized in a homogeneous precipitation of mixed Ni(2+)/Mn(2+) salts at a molar ratio of 2 : 1 via the hydrolysis of hexamethylenetetramine (HMT) and in situ oxidation with H2O2. After anion-exchange, NiMn LDH was exfoliated into unilamellar nanosheets. Subsequent flocculation of NiMn LDH nanosheets with (reduced) graphene oxide (GO/rGO) into superlattice composites was achieved and further tested as electrocatalysts for oxygen evolution reaction (OER). The face-to-face heteroassembly of NiMn LDH nanosheets with conductive rGO at an alternating sequence resulted in a small overpotential of 0.26 V and a Tafel slope of 46 mV per decade, which is much superior to as-exfoliated nanosheets. The analyses of electrochemical activity surface area (ECSA) and impedance spectra clearly indicated that the superlattice structure was ideal in facilitating the migration/transfer of the charge and reactants, revealing the electrochemical energetics and mechanism behind the synergistic effect arising from molecular hybridization. The proof of concept toward total water splitting using the newly developed hybrid electrocatalyst was demonstrated by an electrolysis cell powered by a single AA battery. PMID:27142232

  19. Preparation of polymer/LDH nanocomposite by UV-initiated photopolymerization of acrylate through photoinitiator-modified LDH precursor

    SciTech Connect

    Hu, Lihua; Yuan, Yan; Shi, Wenfang

    2011-02-15

    Graphical abstract: This is the HR-TEM micrograph of UV cured nanocomposite at 5 wt% LDH-2959 loading for a-5 sample. The dark lines are the intersections of LDH platelets. It can be seen that samples a-5 dispersed in the polymer matrix and lost the ordered stacking-structure and show the completely exfoliation after UV curing. This can be explained by the fact that the sample a-5 only containing LDH-2959 exhibited a relative lower photopolymerization rate, which was propitious to further expand the LDH intergallery to form the exfoliated structure. Research highlights: {yields} The UV cured polymer/LDH nanocomposites were prepared through the photopolymerization initiated by the photoinitiator-modified LDH precursor, LDH-2959. {yields} The exfoliated UV cured nanocomposites were achieved in the presence of LDH-2959 only. However, the UV cured nanocomposites prepared using both LDH-2959 and Irgacure 2959 showed the intercalated structure. {yields} Compared with the pure polymer, the exfoliated polymer/LDH nanocomposite showed remarkable enhanced thermal stability and mechanical properties because of their well dispersion in the polymer matrix. -- Abstract: The exfoliated polymer/layered double hydroxide (LDH) nanocomposite by UV-initiated photopolymerization of acrylate systems through an Irgacure 2959-modified LDH precursor (LDH-2959) as a photoinitiator complex was prepared. The LDH-2959 was obtained by the esterification of 2-hydroxy-4'-(2-hydroxyethoxy)-2-methylpropiophenone (Irgacure 2959) with thioglycolic acid, following by the addition reaction with 3-(2,3-epoxypropoxy)propyltrimethoxysilane (KH-560), finally intercalation into the sodium dodecyl sulfate-modified LDH. For comparison, the intercalated polymer/LDH nanocomposite was obtained with additive Irgacure 2959 addition. From the X-ray diffraction (XRD) measurements and HR-TEM observations, the LDH lost the ordered stacking-structure and well dispersed in the polymer matrix at 5 wt% LDH-2959 loading

  20. Synthesis and properties of mecoprop-intercalated layered double hydroxide

    NASA Astrophysics Data System (ADS)

    Ahmed Khan, Modabber; Choi, Choong-Lyeal; Lee, Dong-Hoon; Park, Man; Lim, Bu-Kug; Lee, Jong-Yoon; Choi, Jyung

    2007-08-01

    This study carried out to elucidate the synthesis of MCPP LDH hybrid, release pattern of MCPP from MCPP LDH hybrid and their properties. MCPP LDH hybrid was synthesized from MCPP and Mg Al complex. Release pattern of MCPP from MCPP LDH hybrid was slower in distilled water and soil solution but it was slower in distilled water than soil solution. MCPP LDH hybrid has shown more stable condition than CO32- form of LDH in thermal and acidic condition. Therefore, MCPP LDH hybrid would lead as functional and benign pesticide to minimize the harmful effects on soil environment by bulk herbicides.

  1. Formation of Layered Single- and Double-Metal Hydroxide Precipitates at the Mineral/Water Interface: A Multiple-Scattering XAFS Analysis.

    PubMed

    Scheinost; Sparks

    2000-03-15

    Spectroscopic and microscopic studies have shown that Ni and Co sorption by clay minerals may proceed via formation of surface precipitates. Several studies employing X-ray absorption fine structure (XAFS) spectroscopy suggested the formation of turbostratic, alpha-type metal hydroxides, of layered double hydroxides (LDH) with Al-for-metal substitution, and of 1:1 or 2:1 phyllosilicates. Distinction of these phases is difficult because they have low crystallinity and/or a small mass compared to the sorbents, and because they have similar metal-metal distances in their hydroxide layers/sheets. Distinction of these phases is crucial, however, because they have substantially differing solubilities. In this paper we show that an XAFS beat pattern at about 8 Å(-1) can be used as a fingerprint to unequivocally distinguish LDH from the alpha-type hydroxides and phyllosilicates. Full multiple-scattering simulations and experimental spectra of model compounds indicate that the beat pattern is due to focused multiple scattering at Me/Al ratios between 1 and 4 (Me=Ni, Co). By applying the fingerprint method to new and to already published XAFS data on Ni and Co surface precipitates, we found that LDH preferentially forms in the presence of the Al-containing sorbents pyrophyllite, illite, kaolinite, gibbsite, and alumina above pH 7.0. However, alpha-type metal hydroxides form in the presence of the Al-free sorbents talc, silica, and rutile, and in the presence of the Al-containing clay minerals montmorillonite and vermiculite. We believe that the high permanent charge of these latter minerals prevents or retards the release of Al. When Al is available, the formation of LDH seems to be thermodynamically and/or kinetically favored over the formation of alpha-type hydroxides. Copyright 2000 Academic Press. PMID:10700399

  2. Formation of layered single- and double-metal hydroxide precipitates at the mineral/water interface: A multiple-scattering XAFS analysis

    SciTech Connect

    Scheinost, A.C.; Sparks, D.L.

    2000-03-15

    Spectroscopic and microscopic studies have shown that Ni and Co sorption by clay minerals may proceed via formation of surface precipitates. Several studies employing X-ray absorption fine structure (XAFS) spectroscopy suggested the formation of turbostratic, a-type metal hydroxides, of layered double hydroxides (LDH) with Al-for-metal substitution, and of 1:1 or 2:1 phyllosilicates. Distinction of these phases is difficult because they have low crystallinity and/or a small mass compared to the sorbents, and because they have similar metal-metal distances in their hydroxide layers/sheets. Distinction of these phases is crucial, however, because they have substantially differing solubilities. In this paper the authors show that an XAFS beat pattern at about 8 {angstrom} {sup {minus}1} can be used as a fingerprint to unequivocally distinguish LDH from the {alpha}-type hydroxides and phyllosilicates. Full multiple-scattering simulations and experimental spectra of model compounds indicate that the beat pattern is due to focused multiple scattering at Me/Al ratios between 1 and 4(Me = Ni,Co). By applying the fingerprint method to new and to already published XAFS data on Ni and Co surface precipitates, the authors found that LDH preferentially forms in the presence of the Al-containing sorbents pyrophyllite, illite, kaolinite, gibbsite, and alumina above pH 7.0. However, {alpha}-type metal hydroxides form in the presence of the Al-free sorbents talc, silica, and rutile, and in the presence of the Al-containing clay minerals montmorillonite and vermiculite. The authors believe, that the high permanent charge of these latter minerals prevents or retards the release of Al. When Al is available, the formation of LDH seems to be thermodynamically and/or kinetically favored over the formation of {alpha}-type hydroxides.

  3. Use of layered double hydroxides and their derivatives as adsorbents for inorganic and organic pollutants

    NASA Astrophysics Data System (ADS)

    You, Youwen

    Contamination of surface and groundwaters by hazardous inorganic and organic pollutants has become an increasing threat to the safety of drinking waters. Cleanup of contaminated surface and groundwaters has, therefore, become a major focus of environmental research. Primary objectives of this dissertation study were to examine the adsorption properties of layered double hydroxides (LDHs) and their derivatives for inorganic and organic contaminants and to identify potential technologies that utilize LDHs and their derivatives for environment remediation. Studies examined the adsorption characteristics of anionic selenium, arsenic and dicamba (3,6 dichloro-2-methoxy benzoic acid) on original LDHs and calcined-LDHs. Adsorption of selenium and arsenic on LDHs was a function of pH. Competing anions in solution strongly affected adsorption of all three contaminants, with divalent anions decreasing adsorption more intensely than monovalent anions. Adsorbed selenium, arsenic and dicamba could be released from LDHs in anion solutions. Adsorption isotherms for selenium and arsenic retention could be fitted to a simple Langmuir equation. Calcination processes significantly increased adsorption capacities of LDHs. Because of adsorption-desorpion characteristics, LDHs could be recycled. X-ray diffraction patterns revealed an increase of d-spacing coupling with adsorption of contaminants, verifying the intercalation of contaminants into layer structure of LDHs. Long chain anionic surfactants intercalated into LDHs modified their surface properties, resulting in organo-LDHs with hydrophobic surface properties. Various organo-LDHs were developed by incorporating different surfactants into LDHs via different synthesis methods. Surfactant intercalation properties were examined and the geometrical arrangements of the intercalated surfactants were characterized. Results revealed that surfactant molecules could adopt various configurations within the LDH interlayer space. Intercalation

  4. Ion specific effects on the stability of layered double hydroxide colloids.

    PubMed

    Pavlovic, Marko; Huber, Robin; Adok-Sipiczki, Monika; Nardin, Corinne; Szilagyi, Istvan

    2016-05-01

    Positively charged layered double hydroxide particles composed of Mg(2+) and Al(3+) layer-forming cations and NO3(-) charge compensating anions (MgAl-NO3-LDH) were synthesized and the colloidal stability of their aqueous suspensions was investigated in the presence of inorganic anions of different charges. The formation of the layered structure was confirmed by X-ray diffraction, while the charging and aggregation properties were explored by electrophoresis and light scattering. The monovalent anions adsorb on the oppositely charged surface to a different extent according to their hydration state leading to the Cl(-) > NO3(-) > SCN(-) > HCO3(-) order in surface charge densities. The ions on the right side of the series induce the aggregation of MgAl-NO3-LDH particles at lower concentrations, whereas in the presence of the left ones, the suspensions are stable even at higher salt levels. The adsorption of multivalent anions gave rise to charge neutralization and charge reversal at appropriate concentrations. For some di, tri and tetravalent ions, charge reversal resulted in restabilization of the suspensions in the intermediate salt concentration regime. Stable samples were also observed at low salt levels. Particle aggregation was fast near the charge neutralization point and at high concentrations. These results, which evidence the colloidal stability of MgAl-NO3-LDH in the presence of various anions, are of prime fundamental interest. These are also critical for applications to develop stable suspensions of primary particles for water purification processes, with the aim of the removal of similar anions by ion exchange. PMID:26997621

  5. Comparative X-ray diffraction and infrared spectroscopy study of Zn-Al layered double hydroxides: Vanadate vs nitrate

    NASA Astrophysics Data System (ADS)

    Salak, Andrei N.; Tedim, João; Kuznetsova, Alena I.; Ribeiro, José L.; Vieira, Luís G.; Zheludkevich, Mikhail L.; Ferreira, Mário G. S.

    2012-03-01

    Zn-Al layered double hydroxides (LDH) are promising as nanocontainers of corrosion inhibitors in self-healing corrosion protection coatings. Zn(2)Al-vanadate (Zn/Al = 2:1) is prepared by anion exchange from the parent composition Zn(2)Al-nitrate at pH ˜ 8. Crystal structure and vibrational spectra of both LDHs have been studied in comparison. Their interlayer distances are rather larger than those corresponding to the most compact arrangement of the intercalated anions. Nevertheless, no sign of a turbostratic disorder has been detected in these LDH. Based on the analysis of the spectroscopic data in combination with the XRD results, it has been shown that vanadate anion, which substitutes nitrate at the anion exchange, is pyrovanadate, VO74-. The observed disorder in the hydroxide layers in Zn(2)Al-V2O7 is likely to result from strong interactions between V5+ and Zn2+/Al3. Although Zn(2)Al-NO3 is less disordered than Zn(2)Al-V2O7, it exhibits no long-range order in arrangement of cations in the hydroxide layers.

  6. Photocatalytic property and structural stability of CuAl-based layered double hydroxides

    SciTech Connect

    Lv, Ming; Liu, Haiqiang

    2015-07-15

    Three types of CuMAl layered double hydroxides (LDHs, M=Mg, Zn, Ni) were successfully synthesized by coprecipitation. Powder X-ray diffraction (XRD), inductively coupled plasma atomic emission spectrometry (ICP-AES) and UV–Vis diffuse reflectance spectrum (UV–vis) were used to confirm the formation of as-synthesized solids with good crystal structure. The photocatalytic activity of those LDH materials for CO{sub 2} reduction under visible light was investigated. The experimental results show that CuNiAl-LDHs with narrowest band gap and largest surface areas behave highest efficiency for methanol generation under visible light compared with CuMgAl-LDHs and CuZnAl-LDHs. The CuNiAL-LDH showed high yield for methanol production i.e. 0.210 mmol/g h, which was high efficient. In addition, the influence of the different M{sup 2+} on the structures and stability of the CuMAl-LDHs was also investigated by analyzing the geometric parameters, electronic arrangement, charge populations, hydrogen-bonding, and binding energies by density functional theory (DFT) analysis. The theoretical calculation results show that the chemical stability of LDH materials followed the order of CuMgAl-LDHs>CuZnAl-LDHs>CuNiAl-LDHs, which is just opposite with the photocatalytic activity and band gaps of three materials. - Graphical abstract: The host–guest calculation models and XRD patterns of CuMAl-LDHs: CuMgAl-LDHs (a), CuZnAl-LDHs (b) and CuNiAl-LDHs (c). - Highlights: • Three types of CuMAl layered double hydroxides (LDHs, M=Mg, Zn, Ni) has been synthesized. • CuMgNi shows narrower band gap and more excellent textural properties than other LDHs. • The band gap: CuMgAl

  7. Layered double hydroxide supported gold nanoclusters by glutathione-capped Au nanoclusters precursor method for highly efficient aerobic oxidation of alcohols

    NASA Astrophysics Data System (ADS)

    Li, Lun; Dou, Liguang; Zhang, Hui

    2014-03-01

    M3Al-layered double hydroxide (LDH, M = Mg, Ni, Co) supported Au nanoclusters (AuNCs) catalysts have been prepared for the first time by using water-soluble glutathione-capped Au nanoclusters as precursor. Detailed characterizations show that the ultrafine Au nanoclusters (ca. 1.5 +/- 0.6 nm) were well dispersed on the surface of LDH with a loading of Au below ~0.23 wt% upon synergetic interaction between AuNCs and M3Al-LDH. AuNCs/Mg3Al-LDH-0.23 exhibits much higher catalytic performance for the oxidation of 1-phenylethanol in toluene than Au/Mg3Al-LDH(DP) by the conventional deposition precipitation method and can be applied for a wide range of alcohols without basic additives. This catalyst can also be reused without loss of activity or selectivity. The AuNCs/M(= Ni, Co)3Al-LDH catalysts present even higher alcohol oxidation activity than AuNCs/Mg3Al-LDH. Particularly, AuNCs/Ni3Al-LDH-0.22 exhibits the highest activity (46 500 h-1) for the aerobic oxidation of 1-phenylethanol under solvent-free conditions attributed to its strongest Au-support synergy. The excellent activity and stability of AuNCs/M3Al-LDH catalysts render these materials promising candidates for green base-free selective oxidation of alcohols by molecular oxygen.M3Al-layered double hydroxide (LDH, M = Mg, Ni, Co) supported Au nanoclusters (AuNCs) catalysts have been prepared for the first time by using water-soluble glutathione-capped Au nanoclusters as precursor. Detailed characterizations show that the ultrafine Au nanoclusters (ca. 1.5 +/- 0.6 nm) were well dispersed on the surface of LDH with a loading of Au below ~0.23 wt% upon synergetic interaction between AuNCs and M3Al-LDH. AuNCs/Mg3Al-LDH-0.23 exhibits much higher catalytic performance for the oxidation of 1-phenylethanol in toluene than Au/Mg3Al-LDH(DP) by the conventional deposition precipitation method and can be applied for a wide range of alcohols without basic additives. This catalyst can also be reused without loss of activity

  8. Bioinorganic magnetic core-shell nanocomposites carrying antiarthritic agents: intercalation of ibuprofen and glucuronic acid into Mg-Al-layered double hydroxides supported on magnesium ferrite.

    PubMed

    Ay, Ahmet Nedim; Zümreoglu-Karan, Birgül; Temel, Abidin; Rives, Vicente

    2009-09-21

    This paper describes the synthesis and characterization of a composite constituted by an antiarthritic agent (AA) intercalated into a layered double hydroxide (LDH) supported on magnesium ferrite. Core-shell nanocomposites were prepared by depositing Mg-Al-NO(3)-LDH on a MgFe(2)O(4) core prepared by calcination of a nonstoichiometric Mg-Fe-CO(3)-LDH. Intercalation of ibuprofen and glucuronate anions was performed by ion-exchange with nitrate ions. The structural characteristics of the obtained products were investigated by powder X-ray diffraction, element chemical analysis, Fourier transform infrared spectroscopy, and thermogravimetric analysis. Morphologies of the nanocomposite particles were examined by scanning electron microscopy and transmission electron microscopy. The products were shown to intercalate substantial amounts of AA with enhanced thermal stabilities. Room-temperature magnetic measurements by vibrating sample magnetometry revealed that the products show soft ferromagnetic properties suitable for potential utilization in magnetic arthritis therapy. PMID:19691269

  9. Preparation of 5-benzotriazolyl-4-hydroxy-3- sec-butylbenzenesulfonate anion-intercalated layered double hydroxide and its photostabilizing effect on polypropylene

    NASA Astrophysics Data System (ADS)

    Li, Dianqing; Tuo, Zhenjun; Evans, David G.; Duan, Xue

    2006-10-01

    An organic UV absorber has been intercalated into a layered double hydroxide (LDH) host by ion-exchange method using ZnAl-NO 3-LDH as a precursor with an aqueous solution of the sodium salt of 5-benzotriazolyl-4-hydroxy-3- sec-butylbenzenesulfonic acid (BZO). After intercalation of the UV absorber, the interlayer distance in the LDHs increases from 0.89 to 2.32 nm. Infrared spectra and thermogravimetry and differential thermal analysis (TG-DTA) curves reveal the presence of a complex system of supramolecular host-guest interactions. The thermostability of BZO is markedly enhanced by intercalation in the LDH host. ZnAl-BZO-LDHs/polypropylene composite materials exhibit excellent UV photostability.

  10. Efficient removal of heavy metal ions from aqueous systems with the assembly of anisotropic layered double hydroxide nanocrystals@carbon nanosphere.

    PubMed

    Gong, Jingming; Liu, Ting; Wang, Xiaoqing; Hu, Xianluo; Zhang, Lizhi

    2011-07-15

    We report on the efficient removal of heavy metal ions from simulated wastewater with a nanostructured assembly. The nanoassembly was obtained via direct assembling the performed anisotropic layered double hydroxide nanocrystals (LDH-NCs) onto the surface of carbon nanospheres (labeled as LDH-NCs@CNs). It was found that the maximum adsorption capacity of the nanoassembly toward Cu(2+) was ∼ 19.93 mg g(-1) when the initial Cu(2+) concentration was 10.0 mg L(-1), displaying a high efficiency for the removal of heavy metal ions. The Freundlich adsorption isotherm was applicable to describe the removal processes. Kinetics of the Cu(2+) removal was found to follow pseudo-second-order rate equation. Furthermore, the as-prepared building unit of the assembly, including LDH-NCs, CNs, and the assembly, as well as Cu(2+)-adsorbed assembly, were carefully examined by transmission electron microscopy (TEM), Fourier transform infrared spectroscopy (FT-IR), nitrogen sorption measurements, and X-ray photoelectron spectroscopy (XPS). Based on the characterization results, a possible mechanism of Cu(2+) removal with the assembly of LDH-NCs@CNs was proposed. Comparison experiments show that the adsorption capacity of the resulting LDH-NCs@CNs assembly was much higher than its any building unit alone (CNs or LDH-NCs), exhibiting the deliberation of the assembly on water decontamination. This work provides a very efficient, fast and convenient approach for exploring promising nanoassembly materials for water treatment. PMID:21692502

  11. One-step hydrothermal crystallization of a layered double hydroxide/alumina bilayer film on aluminum and its corrosion resistance properties.

    PubMed

    Guo, Xiaoxiao; Xu, Sailong; Zhao, Lili; Lu, Wei; Zhang, Fazhi; Evans, David G; Duan, Xue

    2009-09-01

    A zinc-aluminum layered double hydroxide (ZnAl-LDH)/alumina bilayer film has been fabricated on an aluminum substrate by a one-step hydrothermal crystallization method. The LDH film was uniform and compact. XRD patterns and SEM images showed that the LDH film was highly oriented with the c-axis of the crystallites parallel to the substrate surface. The alumina layer existing between the LDH film and the substrate was formed prior to the LDH during the crystallization process. Polarization measurements showed that the bilayer film exhibited a low corrosion current density value of 10(-8) A/cm(2), which means that the LDH/alumina bilayer film can effectively protect aluminum from corrosion. Electrochemical impedance spectroscopy (EIS) showed that the impedance of the bilayer was 16 MOmega, meaning that the film served as a passive layer with a high charge transfer resistance. The adhesion between the film and the substrate was very strong which enhances its potential for practical application. PMID:19441823

  12. Structural Characterisation of Complex Layered Double Hydroxides and TGA-GC-MS Study on Thermal Response and Carbonate Contamination in Nitrate- and Organic-Exchanged Hydrotalcites.

    PubMed

    Conterosito, Eleonora; Palin, Luca; Antonioli, Diego; Viterbo, Davide; Mugnaioli, Enrico; Kolb, Ute; Perioli, Luana; Milanesio, Marco; Gianotti, Valentina

    2015-10-12

    Layered double hydroxides (LDHs) are versatile materials used for intercalating bioactive molecules in the fields of pharmaceuticals, nutraceuticals and cosmetics, with the purpose of protecting them from degradation, enhancing their water solubility to increase bioavailability and improving their pharmacokinetic properties and formulation stability. Moreover, LDHs are used in various technological applications to improve stability and processability. The crystal chemistry of hydrotalcite-like compounds was investigated by X-ray powder diffraction (XRPD), automated electron diffraction tomography (ADT) and thermogravimetric analysis (TGA)-GC-MS to shed light on the mechanisms involved in ion exchange and absorption of contaminants, mainly carbonate anions. For the first time, ADT allowed a structural model of LDH_NO3 to be obtained from experiment, shedding light on the conformation of nitrate inside LDH and on the loss of crystallinity due to the layer morphology. The ADT analysis of a hybrid LDH sample (LDH_EUS) clearly revealed an increase in defectivity in this material. XRPD demonstrated that the presence of carbonate can influence the intercalation of organic molecules into LDH, since CO3 -contaminated samples tend to adopt d spacings that are approximate multiples of the d spacing of LDH_CO3 . TGA-GC-MS allowed intercalated and surface- adsorbed organic molecules to be distinguished and quantified, the presence and amount of carbonate to be confirmed, especially at low concentrations (<2 wt %), and the different types and strengths of adsorption to be classified with respect to the temperature of elimination. PMID:26269963

  13. Porous Hybrid Network of Graphene and Metal Oxide Nanosheets as Useful Matrix for Improving the Electrode Performance of Layered Double Hydroxides.

    PubMed

    Gu, Tae-Ha; Gunjakar, Jayavant L; Kim, In Young; Patil, Sharad B; Lee, Jang Mee; Jin, Xiaoyan; Lee, Nam-Suk; Hwang, Seong-Ju

    2015-08-26

    Mesoporous hybrid network of reduced graphene oxide (rG-O) and layered MnO(2) nanosheets could act as an efficient immobilization matrix for improving the electrochemical activity of layered double hydroxide (LDH). The control of MnO(2) /rG-O ratio is crucial in optimizing the porous structure and electrical conductivity of the resulting hybrid structure. The immobilization of Co-Al-LDH on hybrid MnO(2) /rG-O network is more effective in enhancing its electrode activity compared with that of on pure rG-O network. The Co-Al-LDH-rG-O-MnO(2) nanohybrid deliveres a greater specific capacitance than does MnO(2) -free Co-Al-LDH-rG-O nanohybrid. The beneficial effect of MnO(2) incorporation on the electrode performance of nanohybrid is more prominent for higher current density and faster scan rate, underscoring the significant enhancement of the electron transport of Co-Al-LDH-rG-O. This is supported by electrochemical impedance spectroscopy. The present study clearly demonstrates the usefulness of the porously assembled hybrid network of graphene and metal oxide nanosheets as an effective platform for exploring efficient LDH-based functional materials. PMID:25930158

  14. Synthesis and characterization of layered double hydroxides (LDHs) with intercalated chromate ions

    SciTech Connect

    Prasanna, Srinivasa V.; Kamath, P. Vishnu . E-mail: vishnukamath8@hotmail.com; Shivakumara, C.

    2007-06-05

    Chromate intercalated layered double hydroxides (LDHs) having the formula M{sup II} {sub 6}M'{sup III} {sub 2}(OH){sub 16}CrO{sub 4}.4H{sub 2}O (M{sup II} = Ca, Mg, Co, Ni, Zn with M'{sup III} = Al and M{sup II} = Mg, Co, Ni with M'{sup III} = Fe) have been prepared by coprecipitation. The products obtained are replete with stacking disorders. DIFFaX simulations show that the stacking disorders are of three kinds: (i) turbostratic disorder of an originally single layered hexagonal (1H) crystal (ii) random intergrowth of polytypes with hexagonal (2H) and rhombohedral (3R) symmetries and (iii) translation of randomly chosen layers by (2/3, 1/3, z) and (1/3, 2/3, z) leading to stacking faults having a local structure of rhombohedral symmetry. IR spectra show that the CrO{sub 4} {sup 2-} ion is incorporated either in the T {sub d} or in the C {sub 3v} symmetry. The interlayer spacing in the latter case is 7.3 A characteristic of a single atom thick interlayer showing that the CrO{sub 4} {sup 2-} ion is grafted to the metal hydroxide slab. On thermal treatment, the CrO{sub 4} {sup 2-} ion transforms into Cr(III) and is incorporated into the spinel oxide or phase separates as Cr{sub 2}O{sub 3}. In the LDH of Mg with Al, Cr(III) remains in the MgO lattice as a defect and promotes the reconstruction of the LDH on soaking in water. In different LDHs, 18-50% of the CrO{sub 4} {sup 2-} ion is replaceable with carbonate anions showing only partial mineralization of the water-soluble chromate. The extent of replaceable chromates depends upon the solubility of the corresponding LDH, which in turn is determined by the solubility of the MCrO{sub 4}. These studies have profound implications for the possible use of LDHs for chromate amelioration in green chemistry.

  15. Local environment and composition of magnesium gallium layered double hydroxides determined from solid-state {sup 1}H and {sup 71}Ga NMR spectroscopy

    SciTech Connect

    Petersen, Line Boisen; Lipton, Andrew S.; Zorin, Vadim; Nielsen, Ulla Gro

    2014-11-15

    Ordering of gallium(III) in a series of magnesium gallium (MgGa) layered double hydroxides (LDHs), [Mg{sub 1−x}Ga{sub x}(OH){sub 2}(NO{sub 3}){sub x}·yH{sub 2}O] was investigated using solid-state {sup 1}H and {sup 71}Ga NMR spectroscopy as well as powder X-ray diffraction. Three different proton environments from Mg{sub 3}-OH, Mg{sub 2}Ga-OH and intergallery water molecules were assigned and quantified using ({sup 1}H,{sup 71}Ga) HETCOR and {sup 1}H MAS NMR. A single {sup 71}Ga site originating from the unique Ga site in the MgGa LDH's was observed in {sup 71}Ga MAS and 3QMAS NMR spectra. Both {sup 1}H MAS NMR spectra recorded at 21.1 T (900 MHz) and elemental analysis show that the synthesized MgGa LDH's had a lower Mg:Ga ratio than that of the starting reactant solution. The origin of this is the formation of soluble [Ga(OH){sub 4}]{sup −} complexes formed during synthesis, and not due to formation of insoluble gallium (oxy)hydroxides. No sign of Ga-O-Ga connectivities or defects were detected for the MgGa LDH's. - Graphical abstract: Two types of hydroxides groups are observed in magnesium gallium layered double hydroxides revealing an ordering of Ga in the cation layer. - Highlights: • Ga is ordered in our magnesium gallium layered double hydroxides. • Ga depletion due to formation of soluble Ga complexes during synthesis. • No sign of Ga rich regions in magnesium gallium LDHs. • Solid state {sup 1}H and {sup 71}Ga give detailed insight into the structure.

  16. New treatment method for boron in aqueous solutions using Mg-Al layered double hydroxide: Kinetics and equilibrium studies.

    PubMed

    Kameda, Tomohito; Oba, Jumpei; Yoshioka, Toshiaki

    2015-08-15

    Mg-Al layered double hydroxides (LDHs) intercalated with NO3(-) (NO3 · Mg - Al LDHs) and with Cl(-) (Cl · Mg - Al LDHs) were found to take up boron from aqueous solutions. Boron was removed by anion exchange of B(OH)4(-) in solution with NO3(-) and Cl(-) intercalated in the interlayer of the LDH. Using three times the stoichiometric quantity of NO3 · Mg-Al LDH, the residual concentration of B decreased from 100 to 1.9 mg L(-1) in 120 min. Using five times the stoichiometric quantity of Cl · Mg - Al LDH, the residual concentration of B decreased from 100 to 5.6 mg L(-1) in 120 min. It must be emphasized that, in both cases, the residual concentration of B was less than the effluent standards in Japan (10 mg L(-1)). The rate-determining step of B removal by the NO3 · Mg - Al and Cl · Mg - Al LDHs was found to be chemical adsorption involving anion exchange of B(OH)4(-) with intercalated NO3(-) and Cl(-). The removal of B was well described by a pseudo second-order kinetic equation. The adsorption of B by NO3 · Mg - Al LDH and Cl · Mg - Al LDH followed a Langmuir-type adsorption. The values of the maximum adsorption and the equilibrium adsorption constant were 3.6 mmol g(-1) and 1.7, respectively, for NO3 · Mg - Al LDH, and 3.8 mmol g(-1) and 0.7, respectively, for Cl · Mg-Al LDH. The B(OH)4(-) in B(OH)4 · Mg - Al LDH produced by removal of B was found to undergo anion exchange with NO3(-) and Cl(-) in solution. The NO3 · Mg - Al and Cl · Mg - Al LDHs obtained after this regeneration treatment were able to remove B from aqueous solutions, indicating the possibility of recycling NO3 · Mg - Al and Cl · Mg - Al LDHs for B removal. PMID:25827268

  17. Highly Enhanced Photoelectrochemical Water Oxidation Efficiency Based on Triadic Quantum Dot/Layered Double Hydroxide/BiVO4 Photoanodes.

    PubMed

    Tang, Yanqun; Wang, Ruirui; Yang, Ye; Yan, Dongpeng; Xiang, Xu

    2016-08-01

    The water oxidation half-reaction is considered to be a bottleneck for achieving highly efficient solar-driven water splitting due to its multiproton-coupled four-electron process and sluggish kinetics. Herein, a triadic photoanode consisting of dual-sized CdTe quantum dots (QDs), Co-based layered double hydroxide (LDH) nanosheets, and BiVO4 particles, that is, QD@LDH@BiVO4, was designed. Two sets of consecutive Type-II band alignments were constructed to improve photogenerated electron-hole separation in the triadic structure. The efficient charge separation resulted in a 2-fold enhancement of the photocurrent of the QD@LDH@BiVO4 photoanode. A significantly enhanced oxidation efficiency reaching above 90% in the low bias region (i.e., E < 0.8 V vs RHE) could be critical in determining the overall performance of a complete photoelectrochemical cell. The faradaic efficiency for water oxidation was almost 90%. The conduction band energy of QDs is ∼1.0 V more negative than that of LDH, favorable for the electron injection to LDH and enabling a more efficient hole separation. The enhanced photon-to-current conversion efficiency and improved water oxidation efficiency of the triadic structure may result from the non-negligible contribution of hot electrons or holes generated in QDs. Such a band-matching and multidimensional triadic architecture could be a promising strategy for achieving high-efficiency photoanodes by sufficiently utilizing and maximizing the functionalities of QDs. PMID:27419597

  18. In-syringe extraction using dissolvable layered double hydroxide-polymer sponges templated from hierarchically porous coordination polymers.

    PubMed

    Ghani, Milad; Frizzarin, Rejane M; Maya, Fernando; Cerdà, Víctor

    2016-07-01

    Herein we report the use of cobalt porous coordination polymers (PCP) as intermediates to prepare advanced extraction media based on layered double hydroxides (LDH) supported on melamine polymer foam. The obtained dissolvable Ni-Co LDH composite sponges can be molded and used as sorbent for the in-syringe solid-phase extraction (SPE) of phenolic acids from fruit juices. The proposed sorbent is obtained due to the surfactant-assisted self-assembly of Co(II)/imidazolate PCPs on commercially available melamine foam, followed by the in situ conversion of the PCP into the final dissolvable LDH coating. Advantageous features for SPE are obtained by using PCPs with hierarchical porosity (HPCPs). The LDH-sponge prepared using intermediate HPCPs (HLDH-sponge) is placed in the headspace of a glass syringe, enabling flow-through extraction followed by analyte elution by the dissolution of the LDH coating in acidic conditions. Three phenolic acids (gallic acid, p-hydroxybenzoic acid and caffeic acid) were extracted and quantified using high performance liquid chromatography. Using a 5mL sample volume, the obtained detection limits were 0.15-0.35μgL(-1). The proposed method for the preparation of HLDH-sponges showed a good reproducibility as observed from the intra- and inter-day RSD's, which were <10% for all analytes. The batch-to-batch reproducibility for three different batches of HLDH-sponges was 10.6-11.2%. Enrichment factors of 15-21 were obtained. The HLDH-sponges were applied satisfactorily to the determination of phenolic acids in natural and commercial fruit juices, obtaining relative recoveries among 89.7-95.3%. PMID:27247213

  19. Effect of inorganic and organic ligands on the sorption/desorption of arsenate on/from Al-Mg and Fe-Mg layered double hydroxides

    NASA Astrophysics Data System (ADS)

    Caporale, A. G.; Pigna, M.; Dynes, J. J.; Cozzolino, V.; Zhu, J.; Violante, A.

    2012-04-01

    In recent decades, a class of anionic clays known as layered double hydroxides (LDHs) has attracted substantial attention due to the potential use in many applications, such as photochemistry, electrochemistry, polymerization, magnetization and biomedical science. There has also been considerable interest in using LDHs as adsorbents to remove environmental contaminants due to their large surface area, high anion exchange capacity and good thermal stability. We studied the sorption of arsenate on Al-Mg and Fe-Mg layered double hydroxides (easily reproducible at low-cost) as affected by pH and varying concentrations of inorganic (nitrate, nitrite, phosphate, selenite and sulphate) and organic (oxalate and tartrate) ligands, ii) the effect of residence time on the arsenate desorption by these ligands, and iii) the kinetics of arsenate desorption by phosphate. The Fe-Mg-LDH sorbed nearly twice the amount of arsenate compared to the Al-Mg-LDH, due, in part, to its greater surface area and lower degree of crystallinity. Moreover, the Fe-Mg-LDH sorbed more arsenate than phosphate, in contrast to the Al-Mg-LDH, which adsorbed more phosphate than arsenate, probably because of the greater affinity of arsenate than phosphate for Fe sites and, vice versa, the greater affinity of phosphate than arsenate for Al sites. Arsenate sorption onto samples decreased by increasing pH, due, maybe, to the high affinity of hydroxyl ions for LDHs and/or to the value of zero point charge of two sorbents. The rate of decline in the amount of arsenate sorbed was, however, relatively constant, decreasing the fastest for the Fe-Mg-LDH compared to the Al-Mg-LDH. The capacity of ligands to inhibit the fixation of arsenate followed the sequence: nitrate < nitrite < sulphate < selenite < tartrate < oxalate << phosphate on Al-Mg-LDH and nitrate < sulphate ≈ nitrite < tartrate < oxalate < selenite << phosphate on Fe-Mg-LDH. The inhibition of arsenate sorption increased by increasing the initial

  20. Classical Keggin Intercalated into Layered Double Hydroxides: Facile Preparation and Catalytic Efficiency in Knoevenagel Condensation Reactions.

    PubMed

    Jia, Yueqing; Fang, Yanjun; Zhang, Yingkui; Miras, Haralampos N; Song, Yu-Fei

    2015-10-12

    The family of polyoxometalate (POM) intercalated layered double hydroxide (LDH) composite materials has shown great promise for the design of functional materials with numerous applications. It is known that intercalation of the classical Keggin polyoxometalate (POM) of [PW12 O40 ](3-) (PW12 ) into layered double hydroxides (LDHs) is very unlikely to take place by conventional ion exchange methods due to spatial and geometrical restrictions. In this paper, such an intercalated compound of Mg0.73 Al0.22 (OH)2 [PW12 O40 ]0.04 ⋅0.98 H2 O (Mg3 Al-PW12 ) has been successfully obtained by applying a spontaneous flocculation method. The Mg3 Al-PW12 has been fully characterized by using a wide range of methods (XRD, SEM, TEM, XPS, EDX, XPS, FT-IR, NMR, BET). XRD patterns of Mg3 Al-PW12 exhibit no impurity phase usually observed next to the (003) diffraction peak. Subsequent application of the Mg3 Al-PW12 as catalyst in Knoevenagel condensation reactions of various aldehydes and ketones with Z-CH2 -Z' type substrates (ethyl cyanoacetate and malononitrile) at 60 °C in mixed solvents (V2-propanol :Vwater =2:1) demonstrated highly efficient catalytic activity. The synergistic effect between the acidic and basic sites of the Mg3 Al-PW12 composite proved to be crucial for the efficiency of the condensation reactions. Additionally, the Mg3 Al-PW12 -catalyzed Knoevenagel condensation of benzaldehyde with ethyl cyanoacetate demonstrated the highest turnover number (TON) of 47 980 reported so far for this reaction. PMID:26337902

  1. How the method of synthesis governs the local and global structure of zinc aluminum layered double hydroxides

    SciTech Connect

    Pushparaj, Suraj Shiv Charan; Forano, Claude; Prevot, Vanessa; Lipton, Andrew S.; Rees, Gregory; Hanna, John V.; Nielsen, Ulla Gro

    2015-11-10

    A series of zinc aluminum layered double hydroxides (ZnAl LDHs), [Zn1-xAlx (OH)2Ax,nH2O with A = NO3-, Cl- or CO3] were prepared by the urea and co-precipitation synthesis methods, which allowed for a detailed investigation on how synthesis parameters such as pH, metal ion concentration and post synthesis treatment influence the local and global structure of the LDH product. Information about sample composition, purity, defects and other structural aspects of the LDH products were obtained from powder X-ray diffraction, transmission electron microscopy, micro-Raman, and elemental analysis, as well as solid state 1H, 27Al and 67Zn NMR spectroscopy. Our results show that the urea method results in LDHs, which on the global scale are highly crystalline LDHs, whereas solid state NMR shows the different local environments indicating local disorder most likely linked to the presence of Al-rich phases. However, these Alrich phases are not detected by global range techniques, as they either defects within the LDH particles or separate phase(s) associated with LDHs. In contrast, samples prepared by coprecipitation especially synthesized under careful pH control and subsequently hydrothermal treated have high local order and good crystallinity (particle size). Our results show that both molecular level and macroscopic techniques are needed to assess the composition of LDHs, as the conventional PXRD and TEM analysis of LDHs failed to identify the many structural defects and/or amorphous phases.

  2. Evolution of biogenic amine concentrations in foods through their induced chemiluminescence inactivation of layered double hydroxide nanosheet colloids.

    PubMed

    Wang, Zhihua; Liu, Fang; Lu, Chao

    2014-10-15

    Turn-on/off fluorescence and visual sensors through hydrogen bonding recognition have been clearly established in the literature. There is apparently no good reason to disregard hydrogen bonding-induced inactivation of chemiluminescence (CL). In this work, serving as novel CL catalyst and CL resonance energy transfer acceptor (CRET), layered double hydroxide (LDH) nanosheet colloids can induce a significant increase in the CL intensity of bis(2,4,6-trichlorophenyl) oxalate (TCPO)-H2O2 system. On the other hand, biogenic amines can selectively inhibit the CL intensity of the LDH nanosheet-TCPO-H2O2 system as a result of inactivation of photoluminescence LDH nanosheets through the displacement of O-H ⋯ O bonding by O-H ⋯ N bonding. In addition, histamine is used as a common indicator of food spoilage, and it is found that the CL intensity is linear with histamine concentration in the range of 0.1-100 µM, and the detection limit for histamine (S/N=3) is 3.2 nM. The proposed method has been successfully applied to trace histamine evolution of spoiled fish and pork meat samples, displaying a time-dependent increase in the biogenic amines levels in such samples. PMID:24813913

  3. Biodiesel synthesis using calcined layered double hydroxide catalysts

    SciTech Connect

    Schumaker, J. Link; Crofcheck, Czarena; TAckett, S. Adam; Santillan-Jimenez, Eduardo; Morgan, Tonya; Ji, Yaying; Crocker, Mark; Toops, Todd J

    2008-01-01

    The catalytic properties of calcined Li-Al, Mg-Al and Mg-Fe layered double hydroxides (LDHs) were examined in two transesterification reactions, namely, the reaction of glyceryl tributyrate with methanol, and the reaction of soybean oil with methanol. While the Li-Al catalysts showed high activity in these reactions at the reflux temperature of methanol, the Mg-Fe and Mg-Al catalysts exhibited much lower methyl ester yields. CO2 TPD measurements revealed the presence of sites of weak, medium and strong basicity on both Mg-Al and Li-Al catalysts, the latter showing higher concentrations of medium and strong base sites; by implication, these are the main sites active in transesterification catalyzed by calcined Li-Al LDHs. Maximum activity was observed for the Li-Al catalysts when a calcination temperature of 450-500 aC was applied, corresponding to decomposition of the layered double hydroxide to the mixed oxide without formation of crystalline lithium aluminate phases.

  4. Carboxylate-intercalated layered double hydroxides aged under microwave-hydrothermal treatment

    SciTech Connect

    Benito, P.; Labajos, F.M.; Mafra, L.; Rocha, J.; Rives, V.

    2009-01-15

    Carboxylate-intercalated (terephthalate, TA and oxalate, ox) layered double hydroxides (LDHs) are aged under a microwave-hydrothermal treatment. The influence of the nature of the interlayer anion during the ageing process is studied. Characterization results show that the microwave-hydrothermal method can be extended to synthesize LDHs with anions different than carbonate, like TA. LDH-TA compounds are stable under microwave irradiation for increasing periods of time and the solids show an improved order both in the layers and in the interlayer region as evidenced by powder X-ray diffraction (PXRD), {sup 27}Al MAS NMR and FT-IR spectroscopy. Furthermore, cleaning of the surface through removal of some organic species adsorbed on the surface of the particles also occurs during the microwave-hydrothermal treatment. Conversely, although the expected increase in crystallinity is observed in LDH-ox samples, the side-reaction between Al{sup 3+} and ox is also enhanced under microwave irradiation, and a partial destruction of the structure takes place with an increase in the M{sup 2+}/M{sup 3+} ratio and consequent modification of the cell parameters. - Graphical Abstract: The influence of the nature of the interlayer anion during the ageing process of carboxylate-intercalated (TA and ox) hydrotalcite-like compounds (HTlcs) is studied. Well crystallized for TA-containing compounds were obtained. However, the non-desired side-reaction of ox with the aluminum of the layers is enhanced by the microwaves and a partial destruction of the structure takes place.

  5. Development of an Immunosensor Based on Layered Double Hydroxides for MMR Cancer Biomarker Detection.

    PubMed

    Hammami, M; Soussou, A; Idoudi, F; Cohen-Bouhacina, T; Bouhaouala-Zahar, B; Baccar, Z M

    2015-10-01

    As a potential biomarker for the investigation of cancer inflammatory profiles, macrophage mannose receptor (MMR, CD206) is herein selected to develop an immunosensor based on layered double hydroxide (LDH). Like an endocyte C-type lectin receptor, MMR plays an important role in immune homeostasis by scavenging unwanted mannose glycoproteins. It attracts a progressive attention thanks to its particularly high expression within the tumor microenvironment. There is a great of interest to develop an immunosensor based on an antibody specific to MMR for detection of stroma versus tumor cells. In this work, we studied the feasibility of high sensitive MMR cancer Screen Printed Electrode (SPE) immunosensor. Working electrode of commercialized SPE was modified by immobilization of specific antibody (anti-MMR) into thin layer of LDH nanomaterials. Structural, morphological, and surface properties of LDHs were studied by X-Ray diffraction, atomic force microscopy and Infrared spectroscopy in ATR. Cyclic Voltammetry technique was used to study interaction between the human recombinant MMR protein (rHu-MMR, NSO derived) and an immobilized antibody into developed immunosensor. High specific response of -11.72 μA/ng.mL(-1) (with a correlation coefficient of R(2)=0.994 ) were obtained in linear range of 0.05 ng/mL to 10.0 ng/mL of specific recombinant antigen. The limit of detection (LOD) was less than 15.0 pg/mL. From these attractive results, the feasibility of an electrochemical immunosensor for cancer was proved. Additional experiments to study stability and reproducibility the immunosensor should be completed in perspective to use these anti-MMR based immunosensors for sensing human MMR in patient biopsies and sera. PMID:26316191

  6. Delaminated Layered Double Hydroxide Nanosheets as an Efficient Vector for DNA Delivery.

    PubMed

    Wang, Junya; Bao, Wenlong; Umar, Ahmad; Wang, Qiang; O'Hare, Dermot; Wan, Yinglang

    2016-05-01

    The performance of delaminated Mg-Al-lactate and Mg-Al-acetate layered double hydroxides (LDHs) nanosheets (Mg-Al-lactate-NS, Mg-Al-acetate-NS) as efficient vectors for DNA adsorption and delivery to 293T cells was investigated. Mg-Al-lactate and Mg-Al-acetate LDHs were delaminated into single layers in water and were characterized using XRD, SEM, TEM, and Zeta potential measurements. The salmon sperm DNA adsorption capacity of Mg-Al-lactate-NS and Mg-Al-acetate-NS were evaluated by varying the adsorbent dosage and contacting time, which suggested that Mg-Al-lactate-NS had much higher adsorption capacity (649.6 μg mg-1) than that of Mg-Al-acetate-NS (340.0 μg mg(-1)). XRD analysis indicated that after DNA adsorption the Mg-Al-lactate-NS-DNA bio-inorganic nanohybrid still stayed in an exfoliated form. Due to the difficulty in separating the Mg-Al-lactate-NS-DNA from solution, electrophoresis analysis was also applied to detect the free DNA in solution after adsorption. Cytotoxicity studies using 293T cells verified that Mg-Al-lactate-NS was less toxic than Mg-Al-acetate-NS as a smaller dose of this LDH was needed to deliver the same amount of salmon DNA to 293T cells. Cellular uptake and confocal imaging studies demonstrated that Mg-Al-lactate-NS was successful in transfection of ssDNA-FITC into 293T cells. However, the FITC-coupled single strand DNA was failed to be internalized into these cells. The excellent DNA adsorption and delivery capacities indicate that delaminated Mg-Al-lactate LDHs nanosheets are a better DNA vector than bulk phase LDH. PMID:27305815

  7. Removal of boron from oilfield wastewater via adsorption with synthetic layered double hydroxides.

    PubMed

    Delazare, Thais; Ferreira, Letícia P; Ribeiro, Nielson F P; Souza, Mariana M V M; Campos, Juacyara C; Yokoyama, Lídia

    2014-01-01

    Hydrotalcite is a layered double hydroxide (LDH) consisting of brucite-like sheets of metal ions (Mg-Al). In this work, hydrotalcites were synthesized, and boron removal from oilfield wastewater was evaluated. LDHs were synthesized using the co-precipitation method. The calcined products (CLDHs) were obtained by heating at 500°C and characterized using X-ray diffraction, X-ray fluorescence, thermogravimetric analysis and the specific surface area (BET). The affinity of LDHs for borate ions was evaluated for calcined and uncalcined LDHs as a function of contact time, initial pH of the oilfield wastewater (pH ∼ 9) and the LDH surface area. The tests were conducted at room temperature (approximately 25ºC). The results indicated that 10 min were needed to reach a state of equilibrium during boron removal for calcined LDHs due to the high surface area (202.3 m(2) g(-1)) regardless of the initial pH of the oilfield wastewater, which resulted from the high buffering capacity of the LDHs. The adsorption capacity increased as the adsorbents levels increased for the range studied. After treatment of the oilfield wastewater containing 30 mg L(-1) of boron with Mg-Al-CO3-LDHs, the final concentration of boron was within the discharge limit set by current Brazilian environmental legislation, which is 5 mg L(-1). Pseudo-first-order and pseudo-second-order kinetic models were tested, and the latter was found to fit the experimental data better. Isotherms for boron adsorption by CLDHs were well described using the Langmuir and Freundlich equations. PMID:24766593

  8. Synthesis, structure refinement and chromate sorption characteristics of an Al-rich bayerite-based layered double hydroxide

    SciTech Connect

    Britto, Sylvia Kamath, P. Vishnu

    2014-07-01

    “Imbibition” of Zn{sup 2+} ions into the cation vacancies of bayerite–Al(OH){sub 3} and NO{sub 3}{sup −} ions into the interlayer gallery yields an Al-rich layered double hydroxide with Al/Zn ratio ∼3. NO{sub 3}{sup −} ions are intercalated with their molecular planes inclined at an angle to the plane of the metal hydroxide slab and bonded to it by hydrogen bonds. Rietveld refinement of the structure shows that the monoclinic symmetry of the precursor bayerite is preserved in the product, showing that the imbibition is topochemical in nature. The nitrate ion is labile and is quantitatively replaced by CrO{sub 4}{sup 2−} ions from solution. The uptake of CrO{sub 4}{sup 2−} ions follows a Langmuir adsorption isotherm, thus showing that the hydroxide is a candidate material for green chemistry applications for the removal of CrO{sub 4}{sup 2−} ions from waste water. Rietveld refinement of the structure of the hydroxide after CrO{sub 4}{sup 2−} inclusion reveals that the CrO{sub 4}{sup 2−} ion is intercalated with one of its 2-fold axes parallel to the b-crystallographic axis of the crystal, also the principal 2 axis of the monoclinic cell. - Graphical abstract: The structure of the [Zn–Al4-nitrate] LDH viewed along the a-axis. - Highlights: • Synthesis of Al-rich layered double hydroxide with Al/Zn ratio ∼3. • Rietveld refinement indicates that the imbibition of Zn into Al(OH){sub 3} is topochemical in nature. • The uptake of CrO{sub 4}{sup 2−} ions follows a Langmuir adsorption isotherm.

  9. Electrochemical immunosensor with NiAl-layered double hydroxide/graphene nanocomposites and hollow gold nanospheres double-assisted signal amplification.

    PubMed

    Qiao, Lu; Guo, Yemin; Sun, Xia; Jiao, Yancui; Wang, Xiangyou

    2015-08-01

    A sensitive electrochemical immunosensor based on NiAl-layered double hydroxide/graphene nanocomposites (NiAl-LDH/G) and hollow gold nanospheres (HGNs) was proposed for chlorpyrifos detection. The NiAl-LDH/G was prepared using a conventional coprecipitation process and reduction of the supporting graphene oxide. Subsequently, the nanocomposites were dispersed with chitosan (CS). The NiAl-LDH/G possessed good electrochemical behavior and high binding affinity to the electrode. The high surface areas of HGNs and the vast aminos and hydroxyls of CS provided a platform for the covalently crosslinking of antibody. Under optimal conditions, the immunosensor exhibited a wide linear range from 5 to 150 μg/mL and from 150 to 2 μg/mL, with a detection limit of 0.052 ng/mL. The detection results showed good agreement with standard gas chromatography method. The constructed immunosensor exhibited good reproducibility, high specificity, acceptable stability and regeneration performance, which provided a new promising tool for chlorpyrifos detection in real samples. PMID:25801002

  10. Cu2O Photocathode for Low Bias Photoelectrochemical Water Splitting Enabled by NiFe-Layered Double Hydroxide Co-Catalyst

    PubMed Central

    Qi, Huan; Wolfe, Jonathan; Fichou, Denis; Chen, Zhong

    2016-01-01

    Layered double hydroxides (LDHs) are bimetallic hydroxides that currently attract considerable attention as co-catalysts in photoelectrochemical (PEC) systems in view of water splitting under solar light. A wide spectrum of LDHs can be easily prepared on demand by tuning their chemical composition and structural morphology. We describe here the electrochemical growth of NiFe-LDH overlayers on Cu2O electrodes and study their PEC behavior. By using the modified Cu2O/NiFe-LDH electrodes we observe a remarkable seven-fold increase of the photocurrent intensity under an applied voltage as low as −0.2 V vs Ag/AgCl. The origin of such a pronounced effect is the improved electron transfer towards the electrolyte brought by the NiFe-LDH overlayer due to an appropriate energy level alignment. Long-term photostability tests reveal that Cu2O/NiFe-LDH photocathodes show no photocurrent loss after 40 hours of operation under light at −0.2 V vs Ag/AgCl low bias condition. These improved performances make Cu2O/NiFe-LDH a suitable photocathode material for low voltage H2 production. Indeed, after 8 hours of H2 production under −0.2 V vs Ag/AgCl the PEC cell delivers a 78% faradaic efficiency. This unprecedented use of Cu2O/NiFe-LDH as an efficient photocathode opens new perspectives in view of low biasd or self-biased PEC water splitting under sunlight illumination. PMID:27487918

  11. Cu2O Photocathode for Low Bias Photoelectrochemical Water Splitting Enabled by NiFe-Layered Double Hydroxide Co-Catalyst.

    PubMed

    Qi, Huan; Wolfe, Jonathan; Fichou, Denis; Chen, Zhong

    2016-01-01

    Layered double hydroxides (LDHs) are bimetallic hydroxides that currently attract considerable attention as co-catalysts in photoelectrochemical (PEC) systems in view of water splitting under solar light. A wide spectrum of LDHs can be easily prepared on demand by tuning their chemical composition and structural morphology. We describe here the electrochemical growth of NiFe-LDH overlayers on Cu2O electrodes and study their PEC behavior. By using the modified Cu2O/NiFe-LDH electrodes we observe a remarkable seven-fold increase of the photocurrent intensity under an applied voltage as low as -0.2 V vs Ag/AgCl. The origin of such a pronounced effect is the improved electron transfer towards the electrolyte brought by the NiFe-LDH overlayer due to an appropriate energy level alignment. Long-term photostability tests reveal that Cu2O/NiFe-LDH photocathodes show no photocurrent loss after 40 hours of operation under light at -0.2 V vs Ag/AgCl low bias condition. These improved performances make Cu2O/NiFe-LDH a suitable photocathode material for low voltage H2 production. Indeed, after 8 hours of H2 production under -0.2 V vs Ag/AgCl the PEC cell delivers a 78% faradaic efficiency. This unprecedented use of Cu2O/NiFe-LDH as an efficient photocathode opens new perspectives in view of low biasd or self-biased PEC water splitting under sunlight illumination. PMID:27487918

  12. Cu2O Photocathode for Low Bias Photoelectrochemical Water Splitting Enabled by NiFe-Layered Double Hydroxide Co-Catalyst

    NASA Astrophysics Data System (ADS)

    Qi, Huan; Wolfe, Jonathan; Fichou, Denis; Chen, Zhong

    2016-08-01

    Layered double hydroxides (LDHs) are bimetallic hydroxides that currently attract considerable attention as co-catalysts in photoelectrochemical (PEC) systems in view of water splitting under solar light. A wide spectrum of LDHs can be easily prepared on demand by tuning their chemical composition and structural morphology. We describe here the electrochemical growth of NiFe-LDH overlayers on Cu2O electrodes and study their PEC behavior. By using the modified Cu2O/NiFe-LDH electrodes we observe a remarkable seven-fold increase of the photocurrent intensity under an applied voltage as low as ‑0.2 V vs Ag/AgCl. The origin of such a pronounced effect is the improved electron transfer towards the electrolyte brought by the NiFe-LDH overlayer due to an appropriate energy level alignment. Long-term photostability tests reveal that Cu2O/NiFe-LDH photocathodes show no photocurrent loss after 40 hours of operation under light at ‑0.2 V vs Ag/AgCl low bias condition. These improved performances make Cu2O/NiFe-LDH a suitable photocathode material for low voltage H2 production. Indeed, after 8 hours of H2 production under ‑0.2 V vs Ag/AgCl the PEC cell delivers a 78% faradaic efficiency. This unprecedented use of Cu2O/NiFe-LDH as an efficient photocathode opens new perspectives in view of low biasd or self-biased PEC water splitting under sunlight illumination.

  13. Self-assembly preparation of SiO2@Ni-Al layered double hydroxide composites and their enhanced electrorheological characteristics.

    PubMed

    Ji, Xuqiang; Zhang, Wenling; Shan, Lei; Tian, Yu; Liu, Jingquan

    2015-01-01

    The core-shell structured SiO2@Ni-Al layered double hydroxide (LDH) composites were prepared via self-assembly of Ni-Al LDH on the surface of SiO2 spheres. Only coating a layer of ultrathin Ni-Al LDH sheet, the resulting SiO2@Ni-Al LDH composites exhibit significantly enhanced electrorheological (ER) characteristics compared to conventional bare SiO2 spheres. The monodispersed SiO2 spheres with average diameters of 260 nm were synthesized by the hydrolysis of tetraethyl orthosilicate (TEOS), while the shell part, Ni-Al LDH sheet was prepared by the hydrothermal procedure. The morphology of the samples was investigated via scanning transmission electron microscopy (STEM), scanning electron microscopy (SEM) and transmission electron microscopy (TEM). The structure of the samples was characterized by X-ray diffraction (XRD). The species and distribution of elements in samples were confirmed by X-ray photoelectron spectroscopy (XPS), Energy dispersive analysis of X-ray (EDX) and elemental mapping in STEM. Subsequently, the ER characteristics of the composites dispersed in insulating oil were characterized by a rotational rheometer. The electric field-stimulated rheological performances (yield stress, viscosity, modulus, etc.) were observed under an external electric field, which is different from the Newtonian state in the free electric field. PMID:26670467

  14. Self-assembly preparation of SiO2@Ni-Al layered double hydroxide composites and their enhanced electrorheological characteristics

    PubMed Central

    Ji, Xuqiang; Zhang, Wenling; Shan, Lei; Tian, Yu; Liu, Jingquan

    2015-01-01

    The core-shell structured SiO2@Ni-Al layered double hydroxide (LDH) composites were prepared via self-assembly of Ni-Al LDH on the surface of SiO2 spheres. Only coating a layer of ultrathin Ni-Al LDH sheet, the resulting SiO2@Ni-Al LDH composites exhibit significantly enhanced electrorheological (ER) characteristics compared to conventional bare SiO2 spheres. The monodispersed SiO2 spheres with average diameters of 260 nm were synthesized by the hydrolysis of tetraethyl orthosilicate (TEOS), while the shell part, Ni-Al LDH sheet was prepared by the hydrothermal procedure. The morphology of the samples was investigated via scanning transmission electron microscopy (STEM), scanning electron microscopy (SEM) and transmission electron microscopy (TEM). The structure of the samples was characterized by X-ray diffraction (XRD). The species and distribution of elements in samples were confirmed by X-ray photoelectron spectroscopy (XPS), Energy dispersive analysis of X-ray (EDX) and elemental mapping in STEM. Subsequently, the ER characteristics of the composites dispersed in insulating oil were characterized by a rotational rheometer. The electric field-stimulated rheological performances (yield stress, viscosity, modulus, etc.) were observed under an external electric field, which is different from the Newtonian state in the free electric field. PMID:26670467

  15. Ethanol Sensor of CdO/Al2O3/CeO2 Obtained from Ce-DOPED Layered Double Hydroxides with High Response and Selectivity

    NASA Astrophysics Data System (ADS)

    Xu, Dongmei; Guan, Meiyu; Xu, Qinghong; Guo, Ying; Wang, Yao

    2013-06-01

    In this paper, Ce-doped CdAl layered double hydroxide (LDH) was first synthesized and the derivative CdO/Al2O3/CeO2 composite oxide was prepared by calcining Ce-doped CdAl LDH. The structure, morphology and chemical state of the Ce doped CdAl LDH and CdO/Al2O3/CeO2 were also investigated by X-ray diffraction (XRD), Fourier transform infrared (FT-IR), solid state nuclear magnetic resonance (SSNMR), scanning electron microscope (SEM) and X-ray photoelectron spectroscopy (XPS). The gas sensing properties of CdO/Al2O3/CeO2 to ethanol were further studied and compared with CdO/Al2O3 prepared from CdAl LDH, CeO2 powder as well as the calcined Ce salt. It turns out that CdO/Al2O3/CeO2 sensor shows best performance in ethanol response. Besides, CdO/Al2O3/CeO2 possesses short response/recovery time (12/72 s) as well as remarkable selectivity in ethanol sensing, which means composite oxides prepared from LDH are very promising in gas sensing application.

  16. Self-assembly preparation of SiO2@Ni-Al layered double hydroxide composites and their enhanced electrorheological characteristics

    NASA Astrophysics Data System (ADS)

    Ji, Xuqiang; Zhang, Wenling; Shan, Lei; Tian, Yu; Liu, Jingquan

    2015-12-01

    The core-shell structured SiO2@Ni-Al layered double hydroxide (LDH) composites were prepared via self-assembly of Ni-Al LDH on the surface of SiO2 spheres. Only coating a layer of ultrathin Ni-Al LDH sheet, the resulting SiO2@Ni-Al LDH composites exhibit significantly enhanced electrorheological (ER) characteristics compared to conventional bare SiO2 spheres. The monodispersed SiO2 spheres with average diameters of 260 nm were synthesized by the hydrolysis of tetraethyl orthosilicate (TEOS), while the shell part, Ni-Al LDH sheet was prepared by the hydrothermal procedure. The morphology of the samples was investigated via scanning transmission electron microscopy (STEM), scanning electron microscopy (SEM) and transmission electron microscopy (TEM). The structure of the samples was characterized by X-ray diffraction (XRD). The species and distribution of elements in samples were confirmed by X-ray photoelectron spectroscopy (XPS), Energy dispersive analysis of X-ray (EDX) and elemental mapping in STEM. Subsequently, the ER characteristics of the composites dispersed in insulating oil were characterized by a rotational rheometer. The electric field-stimulated rheological performances (yield stress, viscosity, modulus, etc.) were observed under an external electric field, which is different from the Newtonian state in the free electric field.

  17. Incorporation of transition metals into Mg Al layered double hydroxides: Coprecipitation of cations vs. their pre-complexation with an anionic chelator

    NASA Astrophysics Data System (ADS)

    Tsyganok, Andrey; Sayari, Abdelhamid

    2006-06-01

    A comparative study on two different methods for preparing Mg-Al layered double hydroxides (LDH) containing various divalent transition metals M ( M=Co, Ni, Cu) has been carried out. The first (conventional) method involved coprecipitation of divalent metals M(II) with Mg(II) and Al(III) cations using carbonate under basic conditions. The second approach was based on the ability of transition metals to form stable anionic chelates with edta 4- (edta 4-=ethylenediaminetetraacetate) that were synthesized and further introduced into LDH by coprecipitation with Mg and Al. The synthesized LDHs were characterized by X-ray diffraction (XRD) and X-ray fluorescence (XRF) methods, thermogravimetry with mass-selective detection of decomposition products (TG-MSD), Fourier transform infrared (FTIR) and Raman spectroscopy techniques. The results obtained were discussed in terms of efficiency of transition metal incorporation into the LDH structure, thermal stability of materials and the ability of metal chelates to intercalate the interlayer space of Mg-Al LDH. Vibrational spectroscopy studies confirmed that the integrity of the metal chelates was preserved upon incorporation into the LDH.

  18. Development of efficient electrocatalysts via molecular hybridization of NiMn layered double hydroxide nanosheets and graphene

    NASA Astrophysics Data System (ADS)

    Ma, Wei; Ma, Renzhi; Wu, Jinghua; Sun, Pengzhan; Liu, Xiaohe; Zhou, Kechao; Sasaki, Takayoshi

    2016-05-01

    Ni2+Mn3+ layered double hydroxide (LDH) nanoplatelets have been hydrothermally synthesized in a homogeneous precipitation of mixed Ni2+/Mn2+ salts at a molar ratio of 2 : 1 via the hydrolysis of hexamethylenetetramine (HMT) and in situ oxidation with H2O2. After anion-exchange, NiMn LDH was exfoliated into unilamellar nanosheets. Subsequent flocculation of NiMn LDH nanosheets with (reduced) graphene oxide (GO/rGO) into superlattice composites was achieved and further tested as electrocatalysts for oxygen evolution reaction (OER). The face-to-face heteroassembly of NiMn LDH nanosheets with conductive rGO at an alternating sequence resulted in a small overpotential of 0.26 V and a Tafel slope of 46 mV per decade, which is much superior to as-exfoliated nanosheets. The analyses of electrochemical activity surface area (ECSA) and impedance spectra clearly indicated that the superlattice structure was ideal in facilitating the migration/transfer of the charge and reactants, revealing the electrochemical energetics and mechanism behind the synergistic effect arising from molecular hybridization. The proof of concept toward total water splitting using the newly developed hybrid electrocatalyst was demonstrated by an electrolysis cell powered by a single AA battery.Ni2+Mn3+ layered double hydroxide (LDH) nanoplatelets have been hydrothermally synthesized in a homogeneous precipitation of mixed Ni2+/Mn2+ salts at a molar ratio of 2 : 1 via the hydrolysis of hexamethylenetetramine (HMT) and in situ oxidation with H2O2. After anion-exchange, NiMn LDH was exfoliated into unilamellar nanosheets. Subsequent flocculation of NiMn LDH nanosheets with (reduced) graphene oxide (GO/rGO) into superlattice composites was achieved and further tested as electrocatalysts for oxygen evolution reaction (OER). The face-to-face heteroassembly of NiMn LDH nanosheets with conductive rGO at an alternating sequence resulted in a small overpotential of 0.26 V and a Tafel slope of 46 mV per decade

  19. Influence of emulsification process on the properties of Pickering emulsions stabilized by layered double hydroxide particles.

    PubMed

    Zhang, Nana; Zhang, Li; Sun, Dejun

    2015-04-28

    This paper reports the influence of emulsification process on the packing of layered double hydroxide (LDH) particles at the aqueous/oil phase interface and the properties of the resulting Pickering emulsions. Emulsions prepared by ultrasonication display superior long-term stability and gel-like characteristics at the dispersed phase volume fraction well below the random close packing limit, whereas emulsions with same compositions prepared by vortex mixing show some extent of sedimentation and liquid-like behaviors. Rheological measurements demonstrate that the zero-shear elastic modulus and yield stress of gel-like emulsions exhibit power-law dependences on particle concentration and independence on aqueous/oil phase ratio. The microstructural origin of this behavior is investigated by optical microscopy, revealing the droplets become strongly adhesive and a heterogeneous percolating network is formed among neighboring droplets. Fluorescent confocal microscopy measurements further confirm that the droplet adhesion is due to particle layers bridging opposite interfaces. In contrast, homogeneous, isolated, and densely packed droplets are present in emulsions prepared by vortex mixing, which results in these systems being dominantly viscous like the suspending fluid. This study shows that the emulsification process can be used as a trigger to modify long-term stability and rheology of solid-stabilized multiphase mixtures, which greatly expands their potential technological applications. PMID:25853297

  20. Synthesis of protocatechuic acid-zinc/aluminium-layered double hydroxide nanocomposite as an anticancer nanodelivery system

    NASA Astrophysics Data System (ADS)

    Barahuie, Farahnaz; Hussein, Mohd Zobir; Gani, Shafinaz Abd; Fakurazi, Sharida; Zainal, Zulkarnain

    2015-01-01

    Protocatechuic acid, an active anticancer agent, has been intercalated into Zn/Al-layered double hydroxide at Zn/Al=2) using two different preparation methods, co-precipitation and ion-exchange, which are labelled as PZAE and PZAC, respectively. The release of protocatechuate from the nanocomposites occurred in a controlled manner and was fitted satisfactorily to pseudo-second order kinetics. The basal spacing of the resulting nanocomposites PZAE and PZAC was 10.2 and 11.0 Å, respectively, indicating successful intercalation of protocatechuate anions into the interlayer galleries of Zn/Al-NO3-LDH in a monolayer arrangement with angles of 24 and 33° from the z-axis in PZAE and PZAC, respectively. The formation of nanocomposites was further confirmed by a Fourier transform infrared study. Thermogravimetric and differential thermogravimetric analyses indicated that the thermal stability of the intercalated protocatechuic acid was significantly enhanced compared to its free protocatechuic acid, and the drug content in the nanocomposites was estimated to be approximately 32.6% in PZAE and 29.2% in PZAC. Both PZAE and PZAC nanocomposites inhibit the growth of human cervical, liver and colorectal cancer cell lines and exhibit no toxic effects towards normal fibroblast 3T3 cell after 72 h of treatment.

  1. Organo-layered double hydroxides composite thin films deposited by laser techniques

    NASA Astrophysics Data System (ADS)

    Birjega, R.; Vlad, A.; Matei, A.; Dumitru, M.; Stokker-Cheregi, F.; Dinescu, M.; Zavoianu, R.; Raditoiu, V.; Corobea, M. C.

    2016-06-01

    We used laser techniques to create hydrophobic thin films of layered double hydroxides (LDHs) and organo-modified LDHs. A LDH based on Zn-Al with Zn2+/Al3+ ratio of 2.5 was used as host material, while dodecyl sulfate (DS), which is an organic surfactant, acted as guest material. Pulsed laser deposition (PLD) and matrix assisted pulsed laser evaporation (MAPLE) were employed for the growth of the films. The organic anions were intercalated in co-precipitation step. The powders were subsequently used either as materials for MAPLE, or they were pressed and used as targets for PLD. The surface topography of the thin films was investigated by atomic force microscopy (AFM), the crystallographic structure of the powders and films was checked by X-ray diffraction. FTIR spectroscopy was used to evidence DS interlayer intercalation, both for powders and the derived films. Contact angle measurements were performed in order to establish the wettability properties of the as-prepared thin films, in view of functionalization applications as hydrophobic surfaces, owing to the effect of DS intercalation.

  2. Polyethyleneimine as a novel desorbent for anionic organic dyes on layered double hydroxide surface.

    PubMed

    Wang, Siming; Li, Zenghe; Lu, Chao

    2015-11-15

    Polyethyleneimine (PEI) is a positively charged polymer with hydrogen-bonding sites and hydrophobic chains. Therefore, it has been clearly established as an efficient adsorbent by means of these native properties in the literatures. However, there is apparently no good reason to disregard the use of PEI as a desired desorbent. Herein, using methyl orange as a model anionic dye, we investigated the desorption performances of PEI toward anionic dyes adsorbed on the surface of CO3-layered double hydroxides (LDHs) in a wide range of pH values. The experiment results showed that the positively charged PEI had very strong desorption capacity for anionic dyes at low pH values (<9.5) through electrostatic attraction between PEI and methyl orange because of the high degree of protonation of PEI. At high pH values (>9.5), PEI existed as neutral molecule, it could desorb methyl orange via hydrogen bonding between the amino groups of it and sulfonate group of methyl orange; simultaneously, the anion-exchange process occurred between abundant hydroxyl anions and anionic methyl orange. The adsorption capacity of the used LDH adsorbent was about 80% after five cycles of adsorption-desorption-regeneration, which was much higher than that conducted by 0.1M NaOH solution. These findings suggested that PEI could be regarded as a promising desorbent for enriching anionic dyes in wastewater and regenerating LDHs through surface adsorption-desorption cycles. PMID:26255712

  3. Synthesis and Characterization of Layered Double Hydroxides and Their Potential as Nonviral Gene Delivery Vehicles

    PubMed Central

    Balcomb, Blake; Singh, Moganavelli; Singh, Sooboo

    2015-01-01

    Layered double hydroxides (LDHs) exhibit characteristic anion-exchange chemistry making them ideal carriers of negatively charged molecules like deoxyribonucleic acid (DNA). In this study, hydrotalcite (Mg−Al) and hydrotalcite-like compounds (Mg−Fe, Zn−Al, and Zn−Fe), also known as LDHs, were evaluated for their potential application as a carrier of DNA. LDHs were prepared by coprecipitation at low supersaturation and characterized by Powder X-ray diffraction (XRD), infrared (IR), Raman, and inductively coupled plasma—optical emission spectroscopy, scanning electron microscopy (SEM), and transmission electron microscopy (TEM). XRD patterns showed strong and sharp diffraction peaks for the (003) and (006) planes indicating well-ordered crystalline materials. TEM images yielded irregular circular to hexagonal-shaped particles of 50–250 nm in size. Varying degrees of DNA binding was observed for all the compounds, and nuclease digestion studies revealed that the LDHs afford some degree of protection to the bound DNA. Minimal toxicity was observed in human embryonic kidney (HEK293), cervical cancer (HeLa) and hepatocellular carcinoma (HepG2) cell lines with most showing a cell viability in excess of 80 %. All LDH complexes promoted significant levels of luciferase gene expression, with the DNA:Mg−Al LDHs proving to be the most efficient in all cell lines. PMID:25969811

  4. Mechanochemical synthesis and intercalation of Ca(II)Fe(III)-layered double hydroxides

    NASA Astrophysics Data System (ADS)

    Ferencz, Zs.; Szabados, M.; Varga, G.; Csendes, Z.; Kukovecz, Á.; Kónya, Z.; Carlson, S.; Sipos, P.; Pálinkó, I.

    2016-01-01

    A mechanochemical method (grinding the components without added water - dry grinding, followed by further grinding in the presence of minute amount of water or NaOH solution - wet grinding) was used in this work for the preparation and intercalation of CaFe-layered double hydroxides (LDHs). Both the pristine LDHs and the amino acid anion (cystinate and tyrosinate) intercalated varieties were prepared by the two-step grinding procedure in a mixer mill. By systematically changing the conditions of the preparation method, a set of parameters could be determined, which led to the formation of close to phase-pure LDH. The optimisation procedure was also applied for the intercalation processes of the amino acid anions. The resulting materials were structurally characterised by a range of methods (X-ray diffractometry, scanning electron microscopy, energy dispersive analysis, thermogravimetry, X-ray absorption and infra-red spectroscopies). It was proven that this simple mechanochemical procedure was able to produce complex organic-inorganic nanocomposites: LDHs intercalated with amino acid anions.

  5. Mg-Al layered double hydroxides (LDHs) and their derived mixed oxides grown by laser techniques

    NASA Astrophysics Data System (ADS)

    Matei, A.; Birjega, R.; Nedelcea, A.; Vlad, A.; Colceag, D.; Ionita, M. D.; Luculescu, C.; Dinescu, M.; Zavoianu, R.; Pavel, O. D.

    2011-04-01

    Layered double hydroxides (LDHs) have been widely studied due to their applications as multifunctional materials, catalysts, host materials, anionic exchangers, adsorbents for environmental contaminants and for the immobilization of biological materials. As thin films, LDHs are good candidates for novel applications as sensors, corrosion resistant coatings or components in electro optical devices. For these applications, lamellar orientation-controlled film has to be fabricated. In this work, the successful deposition of LDH and their derived mixed oxides thin films by laser techniques is reported. Pulsed laser deposition (PLD) and matrix assisted pulsed laser evaporation (MAPLE) were the methods used for thin films deposition. The ability of Mg-Al LDHs as a carrier for metallic particles (Ag) has been considered. Frozen targets containing 10% powder in water were used for MAPLE, while for PLD the targets consisted in dry-pressed pellets. The structure and the surface morphology of the deposited films were examined by X-ray Diffraction, Atomic Force Microscopy, Scanning Electron Microscopy and Secondary Ion Mass Spectrometry.

  6. The structure and stability of CaFe layered double hydroxides with various Ca:Fe ratios studied by Mössbauer spectroscopy, X-ray diffractometry and microscopic analysis

    NASA Astrophysics Data System (ADS)

    Sipiczki, M.; Kuzmann, E.; Homonnay, Z.; Megyeri, J.; Pálinkó, I.; Sipos, P.

    2013-07-01

    The effects of the Ca(II)/Fe(III) ratios on the structure and Fe microenvironments have been studied in layered double hydroxides comprising of Ca(II) and Fe(III) (CaFe-LDH) prepared by the co-precipitation method. The Ca(II)/Fe(III) ratios were varied systematically from 2 to 6 and for characterisation 57Fe Mössbauer spectroscopy, powder X-ray diffractometry and scanning electron microscopy were applied. XRD patterns of the samples at all Ca(II)/Fe(III) ratios exhibited reflections corresponding to CaFe-LDH and 57Fe Mössbauer measurements revealed that Fe(III) was in a high-spin, somewhat disordered octahedral environment. Above the Ca(II)/Fe(III) ratio of 2 the reflections of Ca(OH)2 also appeared. This phase was found to stabilise the LDH phase, while the phase-pure LDH decomposed on ageing.

  7. Synthesis and Characterization of Chitosan-Coated Near-Infrared (NIR) Layered Double Hydroxide-Indocyanine Green Nanocomposites for Potential Applications in Photodynamic Therapy

    PubMed Central

    Wei, Pei-Ru; Kuthati, Yaswanth; Kankala, Ranjith Kumar; Lee, Chia-Hung

    2015-01-01

    We designed a study for photodynamic therapy (PDT) using chitosan coated Mg–Al layered double hydroxide (LDH) nanoparticles as the delivery system. A Food and Drug Administration (FDA) approved near-infrared (NIR) fluorescent dye, indocyanine green (ICG) with photoactive properties was intercalated into amine modified LDH interlayers by ion-exchange. The efficient positively charged polymer (chitosan (CS)) coating was achieved by the cross linkage using surface amine groups modified on the LDH nanoparticle surface with glutaraldehyde as a spacer. The unique hybridization of organic-inorganic nanocomposites rendered more effective and successful photodynamic therapy due to the photosensitizer stabilization in the interlayer of LDH, which prevents the leaching and metabolization of the photosensitizer in the physiological conditions. The results indicated that the polymer coating and the number of polymer coats have a significant impact on the photo-toxicity of the nano-composites. The double layer chitosan coated LDH–NH2–ICG nanoparticles exhibited enhanced photo therapeutic effect compared with uncoated LDH–NH2–ICG and single layer chitosan-coated LDH–NH2–ICG due to the enhanced protection to photosensitizers against photo and thermal degradations. This new class of organic-inorganic hybrid nanocomposites can potentially serve as a platform for future non-invasive cancer diagnosis and therapy. PMID:26340627

  8. Intercalation of papain enzyme into hydrotalcite type layered double hydroxide

    NASA Astrophysics Data System (ADS)

    Zou, N.; Plank, J.

    2012-09-01

    Intercalation of proteolytic enzyme papain into hydrotalcite type LDH structure was achieved by controlled co-precipitation at pH=9.0 in the presence of papain. Characterization of the MgAl-papain-LDH phase was carried out using X-ray powder diffraction (XRD), elemental analysis, infrared spectroscopy (IR) and thermogravimetry (TG). According to XRD, papain was successfully intercalated. The d-value for the basal spacing of MgAl-papain-LDH was found at ˜5.3 nm. Consequently, original papain (hydrodynamic diameter ˜7.2 nm) attains a compressed conformation during intercalation.Formation of MgAl-papain-LDH was confirmed by elemental analysis and transmission electron microscopy (TEM). Under SEM, MgAl-papain-LDH phases appear as nanothin platelets which are intergrown to flower-like aggregates. Steric size and activity of the enzyme was retained after deintercalation from MgAl-LDH framework, as was evidenced by light scattering and UV/vis measurements. Thus, papain is not denatured during intercalation, and LDH is a suitable host structure which can provide a time-controlled release of the biomolecule.

  9. Hierarchical Co-based Porous Layered Double Hydroxide Arrays Derived via Alkali Etching for High-performance Supercapacitors

    PubMed Central

    Abushrenta, Nasser; Wu, Xiaochao; Wang, Junnan; Liu, Junfeng; Sun, Xiaoming

    2015-01-01

    Hierarchical nanoarchitecture and porous structure can both provide advantages for improving the electrochemical performance in energy storage electrodes. Here we report a novel strategy to synthesize new electrode materials, hierarchical Co-based porous layered double hydroxide (PLDH) arrays derived via alkali etching from Co(OH)2@CoAl LDH nanoarrays. This structure not only has the benefits of hierarchical nanoarrays including short ion diffusion path and good charge transport, but also possesses a large contact surface area owing to its porous structure which lead to a high specific capacitance (23.75 F cm−2 or 1734 F g−1 at 5 mA cm−2) and excellent cycling performance (over 85% after 5000 cycles). The enhanced electrode material is a promising candidate for supercapacitors in future application. PMID:26278334

  10. Ultrasonically-enhanced mechanochemical synthesis of CaAl-layered double hydroxides intercalated by a variety of inorganic anions.

    PubMed

    Szabados, Márton; Mészáros, Rebeka; Erdei, Szabolcs; Kónya, Zoltán; Kukovecz, Ákos; Sipos, Pál; Pálinkó, István

    2016-07-01

    CaAl-layered double hydroxides (CaAl-LDHs) were synthesised with various interlayer anions (CO3(2-), F(-), Cl(-), Br(-) and I(-)) by mechanochemical pre-treatment followed by ultrasonic irradiation in aqueous media. The parameters of the syntheses (duration of pre-milling and sonication, quality of the aqueous media, temperature) were altered in order to optimise the procedure and to understand the formation of LDH and other secondary products. The products were characterised by X-ray diffractometry (XRD) and scanning electron microscopy (SEM). The optimisation resulted in close-to-phase-pure CaAl-LDHs, not only with carbonate and chloride interlayer anions, but the hard-to-intercalate bromide and iodide as well. PMID:26964966