甘氨酸存在条件下水热合成可层离双氢氧化物

Exfoliative Mg/Al layered double hydroxide (Mg/Al-LDHGly) was obtained via hydrothermal synthesis in the presence of glycine. The product prepared by hydrothermal reaction for 10 h at 120 ℃ possesses high thermal stability and maximal crystallite size in a, c directions. TEM and SEM analyses show that Mg/AlLDHGly was of well-crystallized hexagonal product with stacks of slightly curved layers. Benefiting from mechanism investigation on its gradual delamination in formamide, rapid delamination of Mg/Al-LDHGly at room temperature was realized, which provided fundamental for preparation of (Mg/Al-LDHGly)/polymer nanocomposites by using exfoliation-adsorption method.     

Photooxidation of polypropylene/layered double hydroxide nanocomposites: Influence of intralamellar cations

The influence of layered double hydroxides (LDHs) on the photooxidation of polypropylene (PP)/LDH nanocomposites was studied under irradiation at long wavelengths (λ > 300 nm, 60 °C and in the presence of oxygen). The influence of hybrid LDHs containing different divalent cations (Mg, Zn or both Mg and Zn) on the photooxidation mechanism of PP and on the rates of oxidation of the matrix was characterised based on infrared analysis. The presence of LDHs modifies the photoproducts accumulating in the PP and the rates of oxidation of PP were changed depending on the divalent cations in the LDH layers. Whereas natural clays, such as montmorillonite (MMt), can lead to a faster degradation of the materials, LDHs (Zn₂-Al-DS, for example) appear to have no inductive effect on polymer oxidation.     

Structural and functional characterisation of a biohybrid material based on acetylcholinesterase and layered double hydroxides

This work describes the use of layered double hydroxides (LDHs) for the immobilisation of acetylcholinesterase (AChE) on insulator/semiconductor solid supports. Different LDHs have been synthesised by a co-precipitation method. Afterwards, biohybrid materials based on AChE-LDH mixtures have been produced using wild and recombinant enzymes. Spectroscopic techniques have confirmed the LDH phase identity and the links created between the LDH and AChE. Spectrophotometric assays have demonstrated that most of the biohybrid materials are functional and stable. Several configurations have been used for AChE immobilisation. The highest catalytic responses have been observed when using wild enzyme and immobilising AChE-LDH mixtures on LDHs previously deposited on the solid supports. LDHs have been demonstrated to be suitable host matrices for AChE immobilisation on electrodes for the subsequent development of electrochemical biosensors.     

Colloid of Delaminated Layered Double Hydroxides： a Novel Type of LDH-based Catalyst

<正>The colloid of delaminated layered double hydroxides(LDHs),a new LDH-based catalyst,is described. The semi-heterogeneous delaminated colloidal MgPdAl-LDH,in which the total surface of catalytic site-bearing lamellae was rendered accessible for chemical reactivity,showed excellent catalysis toward Suzuki reaction.The turnover frequency of this catalyst for Suzuki reaction between bromobenzene and phenylboronic acid is about 8000 h~(-1).     

Thermostable amperometric lactate biosensor with Clostridium thermocelluml-LDH for the measurement of blood lactate

The gene for Clostridium thermocelluml-lactate dehydrogenase enzyme was cloned into pGEX-4T-2 purification vector to supply a source for a thermostable enzyme in order to produce a stable lactate biosensor working at relatively high temperatures. The purified thermostable enzyme (t-LDH) was then immobilized on a gold electrode via polymerization of polygluteraldehyde and pyrrol resulting in a conductive co-polymer. t-LDH working electrode (t-LDHE) was used for determination of lactate in CHES buffer. Amperometric response of the produced electrodes was measured as a function of lactate concentration, at a fixed bias voltage of 200 mV in a three-electrode system. The linear range and sensitivity of the biosensor was investigated at various temperatures in the range of 25-60 °C. The sensitivity t-LDHE increased with increasing the temperature and reached its highest value at 60 °C. The calculated value was nearly 70 times higher as compared to the sensitivity value of the same electrode tested at 25 °C. The sensing parameters of t-LDHE were compared with the electrodes produced by commercially available rabbit muscle LDH (m-LDH). The sensitivity of t-LDHE was nearly 8 times higher than that of m-LDHE. t-LDHE was found to retain its activity for a week incubation at refrigerator (+5 °C), while m-LDHE lost its activity in this period. t-LDHE was also tested in the presence of human blood serum. The results showed that the current increased with increasing concentrations of lactate in the human blood serum and the biosensor is more sensitive to serum lactate as well as the commercial lactate dissolved in serum as compared to the commercial lactate dissolved in CHES buffer.     

Dispersion control and nematic ordering of Ni/Al layered double hydroxide suspensions

In this paper, we report the preparation of aqueous suspensions of Ni/Al layered double hydroxide (LDH) nanoparticles by a non-steady co-precipitation followed by peptization. By choosing suitable peptization temperature and time, well-dispersed suspensions were obtained. Meanwhile, the particle size, shape and size polydispersity can be efficiently controlled. Nematic ordering is observed in colloidal Ni/Al LDH suspensions and confirmed by birefringence observations and SAXS measurements. Furthermore, we showed that the sol-gel transition takes place after a liquid crystalline phase transition in concentrated Ni/Al LDH suspensions. The absence of isotropic-nematic phase separation can be attributed to the fact that the nematic phase droplets are too small to settle to the bottom of the cuvette.     

Synthesis and Release Behavior of a Hybrid of Camptothecin Intercalated Dodecyl Sulfate Modified Layered Double Hydroxide

The intercalation of a non-ionic and poorly water-soluble drug,camptothecin（CPT）,into dodecyl sulfate （DS） modified layered double hydroxide（LDH） was carried out via a secondary intercalation method to obtain a CPT-DS-LDH hybrid.The in vitro CPT release eFxaminations from the hybrid show that the hybrid can well control the release of CPT,which indicates that the hybrid is a potential drug controlled-release system.Moreover,the intercalation kinetics of CPT into the DS modified LDH fits for the pseudo-second-order model.And the release kinetic process of CPT from the CPT-DS-LDH hybrid at pH=4.8 can be described with pseudo-first-order model,while that at pH=7.2 can be described with both pseudo-first-order model and pseudo-second-order model.Meanwhile,the release mechanism of CPT from the CPT-DS-LDH hybrid was discussed.     

彭泽鲫鱼同工酶的研究

本文采用聚丙烯酰胺垂直平板电泳方法,分析了彭泽鲫鱼的肝、肾、心、脑、肌、眼等6种组织中的酯酶(EST)和乳脱酸氢酶(LDH)同工酶电泳图谱。结果表明:彭泽鲫鱼具有丰富的EST和LDH同工酶。在不同的组织中,EST和LDH同工酶谱带各不相同,具有明显的组织特异性。     

The mechanism on the pH value influencing the property of glutamic acid/layered double hydroxide compounds

The influence of zeta potential, altered by the pH value in synthesis, on the property of glutamic acid (Glu for short)/LDH compounds has been studied. It was found that the layer charges increased first then decreased as the pH value increased, and the layer charge had prominent effect on the properties of the samples. The crystallinity degree and the interlayer spacing increased gradually and the morphology changed from tubular or fibrous to platelet structure as the layer charge increased. And a model has been proposed to explain how pH values in the synthesis influence the LDH compound property by altering their layer charges.