一种新型顺式异三核金属[Cu-Mn-Cu]配合物合成、晶体结构和磁性

合成了一种新型不对称Schiff碱铜前体配合物KCuL和一种化学组成为[(CuL)2Mn (H2O)2]·0.5CH3OH·0.5CH3OH的顺式异三核配合物,并通过元素分析、IR谱的方法对其进行了表征（其中H3L = N-(2-{[(1E)-(5-氯-2-羟基苯基)亚甲基]胺基}乙基)-2-羟基苯甲酰胺）。利用X-射线单晶衍射方法对三核配合物的晶体结构进行了测定。该三核配合物的每一晶胞单元含有一个顺式中性异三核分子和两个无序的甲醇分子。中心锰离子Mn2+处于O6形成的变形八面体几何构型,而两个配阴离子[CuL]-在Mn2+周围呈顺式排布。磁性表明该三核配合物不仅具有分子内反铁磁作用,而且三核单元之间具有弱的铁磁交换作用,磁参数分别为J = -12.1 cm-1, g = 2.20 and zj¢ = 1.37 cm-1.     

Surface plasmon resonance and electrochemistry characterization of layer-by-layer self-assembled DNA and Zr4+ thin films, and their interaction with cytochrome c

Through electrostatic layer-by-layer (LbL) assembly, negatively charged calf thymus double stranded DNA (CTds-DNA), and positively charged Zr⁴⁺ ions were alternately deposited on gold substrate modified with chemisorbed cysteamine. Thus-prepared three-dimensional DNA networks were characterized by surface plasmon resonance (SPR) spectroscopy, X-ray photoelectron spectroscopy (XPS) and infrared reflection-absorption spectroscopy (IR-RAS). SPR spectroscopy indicates that the effective thickness of DNA monolayer in the (DNA/Zr⁴⁺)₁ bilayer was 1.5 ± 0.1 nm, which corresponds to the surface coverage of 79% of its full packed monolayer. At the same time, a linear increase of film thickness with increasing number of layers was also confirmed by SPR characterizations. The data of XPS and IR-RAS show that Zr⁴⁺ ions interact with both the phosphate groups and nitrogenous bases of DNA and load into the framework of DNA. Furthermore, the interactions between this composite film and heme protein cytochrome c (Cyt c) were investigated by SPR spectroscopy and electrochemistry. Compared with the adsorption of Cyt c on DNA monolayer, this composite multilayer film can obviously enhance the amount of immobilized Cyt c confirmed by SPR reflectivity-incident angle (R-θ) curves. Cyclic voltammetry (CV) indicates the Cyt c adsorbed on the composite film is electroactive, and the enhancement of peak current in CV indirectly verifies the increase of the amount of immobilized Cyt c.     

A Smart Theranostic Nanocapsule for Spatiotemporally Programmable Photo-Gene Therapy

The therapeutic performance of DNAzyme-involved gene silencing is significantly constrained by inefficient conditional activation and insufficient cofactor supply. Herein, a self-sufficient therapeutic nanosystem was realized through the delicate design of DNAzyme prodrugs and MnO₂ into a biocompatible nanocapsule with tumor-specific recognition/activation features. The indocyanine green (ICG)-modified DNA prodrugs are designed by splitting the DNAzyme and then reconstituted into the exquisite catalyzed hairpin assembly (CHA) amplification circuit. Based on the photothermal activation of ICG, the nanocapsule was disassembled to expose the MnO₂ ingredient which was immediately decomposed into Mn²⁺ ions to supplement an indispensable DNAzyme cofactor on-demand with a concomitant O₂ generation for enhancing the auxiliary phototherapy. The endogenous microRNA catalyzes the amplified assembly of DNA prodrugs via an exquisite CHA principle, leading to the DNAzyme-mediated simultaneous silencing of two key tumor-involved mRNAs. This self-activated theranostic nanocapsule could substantially expand the toolbox for accurate diagnosis and programmable therapeutics.     

Assembly process of CuHCF/MPA multilayers on gold nanoparticles modified electrode and characterization by electrochemical SPR

Gold nanoparticles were deposited onto 2-mercaptoethylamine (MEA)-assembled planar gold thin film to construct gold nanoparticles modified electrode by virtue of a solution-based self-assembly strategy. Subsequently, 3-mercaptopropionic acid (MPA)-bridged copper hexacyanoferrate (CuHCF) multilayers were constructed on the as-prepared gold nanoparticles modified electrode. The resulted multilayer nanostructures were investigated by electrochemical surface plasmon resonance (EC-SPR) and atomic force microscopy (AFM) with primary emphasis upon the effect of the gold nanoparticles on the MPA/CuHCF multilayers growth and their surface morphology. Compared with the multilayer system on a planar gold electrode, the different electrochemical and optical properties might result from higher curvature effect and extraordinary surface-to-volume ratio characteristic of gold nanoparticles and the nanoparticle-selective growth of CuHCF. A dendrimer-like assembly process was proposed to explain the experiment results. This new motif of multilayer on the gold nanoparticles modified electrode was different from that of on a planar gold electrode, indicating a potential application of EC-SPR technique in the study of nanocomposite materials.     

纳米凹土复合α-CD/EPE超分子水凝胶及其性能

将棒状纳米凹凸棒石黏土加入到α-环糊精（α-CD）和PEO-b-PPO-b-PEO（EPE）嵌段聚合物形成的超分子水凝胶中,构建了一种新型复合水凝胶.用X射线衍射仪（XRD）,傅立叶红外光谱仪（FT-IR）,扫描电镜（SEM）和流变测试等方法表征了该复合水凝胶的结构和性能.实验结果显示：加入适量纳米凹土不会破坏α-CD/EPE聚轮烷的聚集结晶特性;当复合水凝胶中纳米凹土的质量分数小于2.5%时,适量的纳米凹土能改善水凝胶海绵状结构的连续性,增加海绵状结构的壁厚和孔隙率;随着纳米凹土含量的增加,复合水凝胶的凝胶化时间减少且刚性和机械强度得到了提高.     

Space symmetry of effective physical constants for biaxial crystals

In eight quadrants,the positive and negative signs of tensor components describing physical properties of biaxial crystals have been given.The distributions of the physical properties described with different order tensors and their space symmetries have been discussed.These results show that the distributions of effective physical constants are symmetrical in the eight quadrants for the orthorhombic system,but there are two and four kinds of distributions for monoclinic and triclinic systems respectively.Thence,to avoid ambiguities and difficulties in characterizing and applying properties of biaxial crystals,we suggest that the really positive directions of the coordinate axes should be defined before the measurements of their physical properties and their device applications.