缬氨酸Schiff碱和N,N’-杂环碱三元铜配合物的合成、 晶体结构及与BSA作用

合成了铜与水杨醛缩缬氨酸Schiff碱(salval)分别和1,10-菲咯啉(phen)及2,2’-联吡啶(bpy)形成的三元配合物[Cu(salval)(phen)] (1), [Cu(salval)(bpy)]•3H2O (2). 通过元素分析, 摩尔电导, IR, UV, TG-DTG对其进行了表征. 配合物2的结构经X射线单晶衍射确定, 三斜晶系, P-1空间群: a＝0.92676(3) nm, b＝1.03143(4) nm, c＝1.25042(3) nm; α＝74.108(2)°, β＝77.2240(10)°, g＝81.5880(10)°, V＝1.11642(6) nm3, Dc＝1.467 g•cm－3, Z＝2, F(000)＝514, 最后吻合因子R1＝0.0441, wR2＝0.0856 [I＞2σ(I)]. 同时用荧光法研究了配合物与牛血清白蛋白(BSA)的相互作用. 结果表明, 两种配合物对BSA的荧光都有较强的猝灭作用, 静态猝灭是引起猝灭的主要原因. 在浓度比c配合物/cBSA为0～10范围内, 配合物1和配合物2在BSA上只有1个结合位点; 25 ℃结合常数KA分别为6.50×105 (1), 4.33×105 (2) L•mol－1; 给体(BSA)与受体(配合物)间的最近距离r分别为3.85 (1), 4.26 (2) nm. 说明两种配合物都能部分插入BSA分子内部, 且配合物1与BSA的作用强于配合物2.     

Minimalism in fabrication of self-organized nanogels holding both anti-cancer drug and targeting moiety

Recent researches to develop nano-carrier systems in anti-cancer drug delivery have focused on more complicated design to improve therapeutic efficacy and to reduce side effects. Although such efforts have great impact to biomedical science and engineering, the complexity has been a huddle because of clinical and economic problems. In order to overcome the problems, a simplest strategy to fabricate nano-carriers to deliver doxorubicin (DOX) was proposed in the present study. Two significant subjects (i) formation of nanoparticles loading and releasing DOX and (ii) binding specificity of them to cells, were examined. Folic acid (FA) was directly coupled with pullulan (Pul) backbone by ester linkage (FA/Pul conjugate) and the degree of substitution (DS) was varied, which were confirmed by 1H NMR and UV spectrophotometry. Light scattering results revealed that the nanogels possessed two major size distributions around 70 and 270 nm in an aqueous solution. Their critical aggregation concentrations (CACs) were less than 10 microg/mL, which are lower than general critical micelle concentrations (CMCs) of low-molecular-weight surfactants. Transmission electron microscopy (TEM) images showed well-dispersed nanogel morphology in a dried state. Depending on the DS, the nanogels showed different DOX-loading and releasing profiles. The DOX release rate from FA8/Pul (with the highest DS) for 24h was slower than that from FA4/or FA6/Pul, indicating that the FA worked as a hydrophobic moiety for drug holding. Cellular uptake of the nanogels (KB cells) was also monitored by confocal microscopy. All nanogels were internalized regardless of the DS of FA. Based on the results, the objectives of this study, to suggest a new method overcoming the complications in the drug carrier design, were successfully verified.     

异维A酸席夫碱酯的合成

以二环己基碳酰亚胺为脱水剂,4-二甲氨基吡啶为催化剂,异维A酸与对羟基苯胺发生酯化反应,生成异维A酸酯(1);1与醛反应,合成了4个异维A酸席夫碱酯,其结构经1H NMR和IR表征.     

A method to determine quercetin by enhanced luminol electrogenerated chemiluminescence (ECL) and quercetin autoxidation

Quercetin greatly enhanced luminol electrochemiluminescence of quercetin in alkaline solution. When the concentration of luminol was 0.1 mol L(-1), the detection limit for quercetin was 2.0x10(-8) mol L(-1) with a linear range from 1.0x10(-7) to 2x10(-5) mol L(-1). The pH and buffer substantially affected ECL intensity. Quercetin was autoxidized in alkaline aqueous solution. The rate of autoxidation of quercetin in various pH buffers and borate concentrations were measured. Borate was found to inhibit quercetin autoxidation and compromise quercetin enhancement effect on luminol ECL to some extent. Two final autoxidation products were identified with LC-MS methods. Autoxidation process was associated with enhancement of ECL intensity. The ROS generated during quercetin autoxidation enhanced the ECL intensity.     

A photoactivatable push-pull fluorophore for single-molecule imaging in live cells

We have reengineered a red-emitting dicyanomethylenedihydrofuran push-pull fluorophore so that it is dark until photoactivated with a short burst of low-intensity violet light. Photoactivation of the dark fluorogen leads to conversion of an azide to an amine, which shifts the absorption to long wavelengths. After photoactivation, the fluorophore is bright and photostable enough to be imaged on the single-molecule level in living cells. This proof-of-principle demonstration provides a new class of bright photoactivatable fluorophores, as are needed for super-resolution imaging schemes that require active control of single molecule emission.     

Simple and generalized synthesis of oxide-metal heterostructured nanoparticles and their applications in multimodal biomedical probes

Heterostructured nanoparticles composed of metals and Fe3O4 or MnO were synthesized by thermal decomposition of mixtures of metal-oleate complexes (for the oxide component) and metal-oleylamine complexes (for the metal component). The products included flowerlike-shaped nanoparticles of Pt-Fe3O4 and Ni-Fe3O4 and snowmanlike-shaped nanoparticles of Ag-MnO and Au-MnO. Powder X-ray diffraction patterns showed that these nanoparticles were composed of face-centered cubic (fcc)-structured Fe3O4 or MnO and fcc-structured metals. The relaxivity values of the Au-MnO and Au-Fe3O4 nanoparticles were similar to those of the MnO and Fe3O4 nanoparticles, respectively. Au-Fe3O4 heterostructured nanoparticles conjugated with two kinds of 12-base oligonucleotide sequences were able to sense a complementary 24-mer sequence, causing nanoparticle aggregation. This hybridization-mediated aggregation was detected by the overall size increase indicated by dynamic light scattering data, the red shift of the surface plasmon band of the Au component, and the enhancement of the signal intensity of the Fe3O4 component in T2-weighted magnetic resonance imaging.     

In situ detection of live cancer cells by using bioprobes based on Au nanoparticles

We fabricate the high-performance probes based on Au nanoparticles (AuNP) for detection of live cancer cell. AuNP were synthesized with narrow sized distribution (ca. 10 nm) by Au salt reduction method and deposited onto the aminated substrate as a cross-linker and hot spot. Herein, AuNP has enabled the easy and efficient immobilization of the antibody (Cetuximab), which can selectively interact with epidermal growth factor receptor (EGFR) on the surface of epidermal cancer, as detecting moiety onto the AuNP-deposited substrate without nanolithography process. After conjugation of Cetuximab with AuNP-deposited substrate, Cetuximab-conjugated probe as a live cancer cell detector (LCCD) could detect EGFR-highexpressed A431 cells related to epithelial cancer with 54-times larger specificity and sensitivity in comparison with EGFR-deficient MCF7 cells. This implies that AuNP-based probes demonstrate abundant potentials for detection and separation of small biomolecules, cells and other chemicals.     

A new antimalarial polyether from a marine Streptomyces sp. H668

The antimalarial guided fractionation of the culture of marine Streptomyces sp. strain H668 led to the isolation of a new polyether metabolite. The structure was determined by comprehensive NMR and MS assignments. This new metabolite showed in vitro antimalarial activity against both the chloroquine-susceptible (D6) and-resistant (W2) clones of Plasmodium falciparum, without cytotoxicity to normal cells (Vero) making it a promising first lead from this marine bacterium.     

Aggregation behavior of a fluorinated surfactant in 1-butyl-3-methylimidazolium ionic liquids

The aggregation behavior of a fluorinated surfactant (FC-4) was studied by surface tension measurements in 1-butyl-3-methylimidazolium tetrafluoroborate ([bmim][BF 4]) and hexafluorophosphate ([bmim][PF 6]) at various temperatures. A series of surface properties, including adsorption efficiency (p C 20), effectiveness of surface tension reduction (Pi CAC), maximum surface excess concentration (Gamma max) and minimum surface area/molecule (A(min)) at the air-water interface were estimated. By comparing the fluorinated surfactant with traditional surfactants, we deduced that the surface activity of the fluorinated surfactant in ILs was superior to the activity of other surfactants. From the CAC values and their temperature dependence, we estimated the thermodynamic parameters of aggregate formation. The thermodynamic parameters indicate that the aggregate of FC-4 in [bmim][BF 4] is a traditional micelle, while the aggregate of FC-4 in [bmim][PF 6] is nanodroplets composed of FC-4 molecules segregated from the solution phase. These results were further confirmed by (1)H NMR measurements.     

一种含联苯的聚醚醚酮酮

聚醚醚酮酮(PEEK)是聚芳醚酮典型品种之一。由于它具有热固性塑料的耐热性,化学稳定性,又具有热塑性塑料的成型加工性,尤其是它的耐高温特性,使它在电子电器,机械仪表,交通运输宇航等领域得到应用。PEEK的T_g=143℃,T_m=334℃。我们用联苯二酚代替对苯二酚,同时加入间位的二氟化物。得到T_g=169℃,T_m=339℃的含联苯的聚醚醚酮酮。它有可能成为使用温度高于PEEK而加工条件与PEEK基本相同的耐高温树脂。