葡萄糖变旋作用中催化剂的活性与金属离子性质的关系

第四周期过渡金属硫酸盐及其水合物作为反应的催化剂已有许多报导。对同一反应,有人探索了催化剂的活性与金属的物理参数(离子半径、电荷、第二电离势……)之间的关系,并建立了一些经验关系式。     

THE AUTOMORPHISMS OF NON—DEFECTIVE ORTHOGONAL GROUPS $\[{\Omega _S}(V)\]$ AND $\[O_s^''\]$ IN CHARACTERISTIC 2

Let $V$ be a non-defective S-dimensional quadratic space over a field $F$ of characteristic 2, $\[F \ne {F_2}\]$. We prove that if there is an exceptional automorphism of either $\[{\Omega _S}(V)\]$ or $\[O_S^''(V)\]$ then $\[{V^\alpha }\]$ has a Cayley algebra structure for some $\[\alpha \]$ in F. Moreover, every exceptional automorphism of $\[O_S^''(V)\]$ has exactly one of the following forms: $$\[{\varphi _1} \circ {\Phi _g}or{\varphi _2} \circ {\Phi _g}\]$$ where $\[{\Phi _g}\]$ is an automorphism of $\[O_S^''(V)\]$ given by conjugation by a semilinear automorphism of V which preserves the quadratic structure, and $\[{\varphi _1}\]$ and $\[{\varphi _2}\]$ are the automorphisms induced by triality principle. Every exceptional automorphism of $\[{\Omega _S}(V)\]$ is the restriction of a unique exceptional automorpliism of $\[O_S^''(V)\]$.     

Sensitive Biomimetic Sensor Based on Molecular Imprinting at Functionalized Indium Tin Oxide Electrodes

We initially report an electrochemical sensing platform based on molecularly imprinted polymers (MIPs) at functionalized Indium Tin Oxide Electrodes (ITO). In this research, aminopropyl-derivatized organosilane aminopropyltriethoxysilane (APTES), which plays the role of functional monomers for template recognition, was firstly self-assembled on an ITO electrode and then dopamine-imprinted sol was spin-coated on the modified surface. APTES which can interact with template dopamine (DA) through hydrogen bonds brought more binding sites located closely to the surface of the ITO electrode, thus made the prepared sensor more sensitive for DA detection. Potential scanning is presented to extract DA from the modified film, thus DA can rapidly and completely leach out. The affinity and selectivity of the resulting biomimetic sensor were characterized using cyclic voltammetry (CV). It exhibited an increased affinity for DA over that of structurally related molecules, the anodic current for DA oxidation depended on the concentration of DA in the linear range from 2×10⁻⁶ M to 0.8×10⁻³ M with a correlation coefficient of 0.9927. In contrast, DA-templated film prepared under identical conditions on a bare ITO showed obviously lower response toward dopamine in solution. It should be noted that potential scanning is a very effective approach for DA extraction, and surface modification of the electrochemical transducer with functional monomers is responsible for the development of MIPs-based highly sensitive biomimetic sensor.     

异双核配合物金属胶束模拟磷酸酯酶催化磷酸单酯水解

 合成和表征了四种含过渡金属离子Cu(Ⅱ)和Ni(Ⅱ)的草酰胺桥联异双核配合物,并将这些配合物与Brij35表面活性剂胶束构成金属胶束作为金属水解酶模拟物用于催化对硝基苯酚磷酸单酯(NPP)水解. 研究了金属胶束对NPP水解反应的催化机理,建立了异双核配合物催化NPP水解的动力学数学模型. 结果表明,四种草酰胺桥联异双核配合物在NPP水解反应中表现出较高的催化活性,随着胶束溶液pH的增大,配合物催化NPP水解的速率提高. 配合物中的两个金属离子在催化NPP水解过程中表现出较好的协同效应.     

DNAzyme‐Loaded Metal–Organic Frameworks (MOFs) for Self‐Sufficient Gene Therapy

DNAzymes have been recognized as potent therapeutic agents for gene therapy, while their inefficient intracellular delivery and insufficient cofactor supply precludes their practical biological applications. Metal–organic frameworks (MOFs) have emerged as promising drug carriers without in‐depth consideration of their disassembled ingredients. Herein, we report a self‐sufficient MOF‐based chlorin e6‐modified DNAzyme (Ce6‐DNAzyme) therapeutic nanosystem for combined gene therapy and photodynamic therapy (PDT). The ZIF‐8 nanoparticles (NPs) could efficiently deliver the therapeutic DNAzyme without degradation into cancer cells. The pH‐responsive ZIF‐8 NPs disassemble with the concomitant release of the guest DNAzyme payloads and the host Zn²⁺ ions that serve, respectively, as messenger RNA‐targeting agent and required DNAzyme cofactors for activating gene therapy. The auxiliary photosensitizer Ce6 could produce reactive oxygen species (ROS) and provide a fluorescence signal for the imaging‐guided gene therapy/PDT.     

Sorption of uranium(VI) from aqueous solution onto magnesium silicate hollow spheres

The sorption of uranium(VI) from aqueous solutions was investigated using synthesized magnesium silicate hollow spheres as a novel adsorbent. Batch experiments were conducted to study the effects of initial pH, amount of adsorbent, contact time and initial U(VI) concentrations on uranium sorption efficiency. The desorbing of U(VI) and the effect of coexisting ions were also investigated. Kinetic studies showed that the sorption followed a pseudo-second-order kinetic model. The Langmuir sorption isotherm model correlates well with the uranium sorption equilibrium data for the concentration range of 25–400 mg/L. The maximum uranium sorption capacity onto magnesium silicate hollow spheres was estimated to be about 107 mg/g under the experimental conditions. Desorption of uranium was achieved using inorganic acid as the desorbing agent. The practical utility of magnesium silicate hollow spheres for U(VI) uptake was investigated with high salt concentration of intercrystalline brine. This work suggests that magnesium silicate hollow spheres can be used as a highly efficient adsorbent for removal of uranium from aqueous solutions.     

Hydrolytic cleavage of p-nitrophenyl picolinate by mononuclear Zn(II) and Co(II) complexes with imidazole derivative in CTAB micellar solution

One new hydroxyl-functionalized imidazole derivative (L) was synthesized and characterized. Further, the related mononuclear zinc(II) and cobalt(II) complexes were prepared and used as mimic hydrolases to catalyze the hydrolytic cleavage of p-nitrophenyl picolinate (PNPP) in buffered aqueous solution and a micellar solution of cetyltrimethylammonium bromide (CTAB). Observations show that for all of catalytic systems, the hydrolysis of PNPP was pH-dependent in the pH range of 7.00–8.20. Besides, hydrolysis rates of PNPP displayed a constant increase with the increasing concentration of substrate. In the case of CoL-containing system, moreover, much greater acceleration for PNPP hydrolysis was observed in comparison with the ZnL-containing system. However, micellar effect of CTAB micelle aggregates on the PNPP hydrolysis was not obvious only showing 1.0?～?1.3 folds rate difference in contrast to buffered aqueous solution.     

A Smart Deoxyribozyme-Programmable Catalytic DNA Circuit for High-Contrast MicroRNA Imaging

Synthetic catalytic DNA circuits have been recognized as a promising signal amplification toolbox for sensitive intracellular imaging, yet their selectivity and efficiency are always constrained by uncontrolled off-site signal leakage and inefficient on-site circuitry activation. Thus, the endogenously controllable on-site exposure/activation of DNA circuits is highly desirable for achieving the selective imaging of live cells. Herein, an endogenously activated DNAzyme strategy was facilely integrated with a catalytic DNA circuit for guiding the selective and efficient microRNA imaging in vivo. To prevent the off-site activation, the circuitry constitute was initially caged without sensing functions, which could be selectively liberated by DNAzyme amplifier to guarantee the high-contrast microRNA imaging in target cells. This intelligent on-site modulation strategy can tremendously expand these molecularly engineered circuits in biological systems.