Label-free and ultrasensitive electrochemiluminescence detection of microRNA based on long-range self-assembled DNA nanostructures

Electrochemiluminescence (ECL) integrates the advantages of electrochemical detection and chemiluminescent techniques. The method has received particular attention because it is highly sensitive and selective, has a wide linear range but low reagent costs. The use of nanomaterials with their unique physical and chemical properties has led to new kinds of biosensors that exhibit high sensitivity and stability. Compared to other nanomaterials, DNA nanostructures are more biocompatible, more hydrophilic, and thus less prone to nonspecific adsorption onto the electrode surface. We describe here a label-free and ultrasensitive ECL biosensor for detecting a cancer-associated microRNA at a femtomolar level. We have designed two auxiliary probes that cause the formation of a long-range self-assembly in the form of a μm-long 1-dimensional DNA concatamer. These can be used as carriers for signal amplification. The intercalation of the ECL probe Ru(phen)₃ ²⁺ into the grooves of the concatamers leads to a substantial increase in ECL intensity. This amplified sensor shows high selectivity for discriminating complementary target and other mismatched RNAs. The biosensor enables the quantification of the expression of microRNA-21 in MCF-7 cells. It also displays very low limits of detection and provides an alternative approach for the detection of RNA or DNA detection in diagnostics and gene analysis.

Ultrasound irradiation promoted catalyst-free construction of formamidine framework using isocyanide as building blocks

Reactions of isocyanides with 2-mercaptobenzothiazole and 2-mercaptobenzoxazole afforded a series of compounds containing formamidine framework in moderate to high yields. These organic transformations were performed under mild and catalyst-free conditions. In addition to promoting the reactions, the use of ultrasound irradiation also allowed the process to be carried out under air atmosphere. A possible reaction mechanism was proposed based on the experimental results.     

高光谱图像技术检测黄瓜叶片的叶绿素叶面分布

以黄瓜叶片为材料,利用高光谱图像技术结合独立分量法(ICA),研究了叶绿素浓度叶面分布的快速、无损检测方法.用高光谱相机采集了80片黄瓜叶子的高光谱图像(408～1117 nm),利用ICA方法提取了高光谱图像的8个独立分量信号,通过逐步线性回归(SMLR)优选出第1、第2和第5个ICA信号,并在此基础上建立了叶绿素浓...     

Synthesis and Crystal Structure of a Novel 1D Mercury（II） Iodide Coordination Polymer Containing 40-Membered Macrocycle

A mercury coordination polymer [Hg3(TizT)2I6]n (Mr = 1921.72, TizT = 2,4,6- tri(imidazole-1-yl)-1,3,5-triazine) containing a 40-membered macrocycle which was constructed by four TizT ligands and four mercury(II) iodide molecules had been synthesized by the reaction of HgI2 with TizT. The complex was characterized by elemental analysis, FT-IR, 1H NMR spectra and X-ray crystallography. The crystal of the complex belongs to the monoclinic system and C2/c space group with a = 35.840(5), b = 8.169(5), c = 14.980(5) , β = 104.466(5)°, Z = 4, V = 4247(3) 3, Dc = 3.006 g·cm-3, μ = 15.223 mm-1, F(000) = 3384, Rint = 0.0504, wR = 0.0833 and constructs a chair-like conformation of cyclohexane one by one, which forms a 1-D polymer through the fashion of fused ring aromatic hydrocarbon. The hydrogen bonds and π-π interactions shape the 2-D network structure. The two compounds excited weak fluorescence.     

新型多氧取代环己烯酮的合成

以莽草酸为起始原料,经酯化、丙酮叉保护顺式邻二羟基、叔丁基二甲硅烷保护羟基、还原、羟基酯化、脱保护基、保护反式邻二羟基、烯丙醇氧化,脱保护基共9步反应,合成了新型(5R,6S)-3-苯甲酰氧基亚甲基-5,6-二羟基-2-环己烯-1-酮,总产率19.3％,其结构经1H NMR,IR和HR-MS表征.     

Design, synthesis and biological characterization of novel inhibitors of CD38

Human CD38 is a novel multi-functional protein that acts not only as an antigen for B-lymphocyte activation, but also as an enzyme catalyzing the synthesis of a Ca(2+) messenger molecule, cyclic ADP-ribose, from NAD(+). It is well established that this novel Ca(2+) signaling enzyme is responsible for regulating a wide range of physiological functions. Based on the crystal structure of the CD38/NAD(+) complex, we synthesized a series of simplified N-substituted nicotinamide derivatives (Compound 1-14). A number of these compounds exhibited moderate inhibition of the NAD(+) utilizing activity of CD38, with Compound 4 showing the highest potency. The crystal structure of CD38/Compound 4 complex and computer simulation of Compound 7 docking to CD38 show a significant role of the nicotinamide moiety and the distal aromatic group of the compounds for substrate recognition by the active site of CD38. Biologically, we showed that both Compounds 4 and 7 effectively relaxed the agonist-induced contraction of muscle preparations from rats and guinea pigs. This study is a rational design of inhibitors for CD38 that exhibit important physiological effects, and can serve as a model for future drug development.     

Total synthesis and absolute configuration of malyngamide W

A concise enantioselective synthesis of malyngamide W (1) and its 2'-epimer was described. The strategy was based on three key steps: (1) ozonolysis of compound 11 which was derived from (R)-(-)-carvone 8, followed by copper-iron-catalyzed rearrangement to give the key cyclohex-2-enone intermediate 5, (2) Nozaki-Hiyama-Kishi coupling reaction between aldehyde 4 and iodide 14 to afford alcohol 3, and (3) asymmetric (R)-CBS reduction of the ketone functionality in compound 21 to establish the C-2' chiral center in the target compound 1. The absolute configuration of malyngamide W (1) was thus confirmed via the synthesis of 1 and 2'-epi-1.     

Comparative study of Puerariae lobatae and Puerariae thomsonii by HPLC-diode array detection-flow injection-chemiluminescence coupled with HPLC-electrospray ionization-MS

An on-line HPLC-diode array detection-flow injection chemiluminescence (HPLC-DAD-FICL) method was applied to estimate the difference of Puerariae lobatae and Puerariae thomsonii. Their chemical and active profiles could be obtained by HPLC-DAD-FICL in one run. Seventeen compounds in two species were tentatively identified by HPLC-electrospray ionization-MS (HPLC-ESI-MS) method. The main antioxidants were rapidly screened by active fingerprints coupled with MS data. Similarity and Hierarchical clustering analysis (HCA) were used to distinguish different samples. The results suggested that the chemical fingerprints of 16 batches of samples were similar by similarity evaluation, while HCA could discriminate the two species. The active fingerprints of Puerariae lobatae and Puerariae thomsonii were significantly different. More antioxidants were found in Puerariae lobatae than in Puerariae thomsonii. Main antioxidants, including 3'-hydroxypuerarin, genistein 8-C-glycoside-xyloside, puerarin, 6″-O-xylosylpuerarin, mirificin and daidzein in two species, may be reasonable markers for the discrimination of the two species. The integrated fingerprint based on the chemical and active characteristics may provide an objective quality evaluation for Puerariae lobatae and Puerariae thomsonii.     

From simple to complex: topological evolution and luminescence variation in a copper(I) pyridylpyrazolate system tuned via second ligating spacers

By systematically varying the geometric length and electronic properties of the second ligating ligands of halogen (Cl(-), Br(-), and I(-)) and pseudohalogen (CN(-), SCN(-), and N(3)(-)) anions, we synthesized 11 isomeric/isostructural copper(I) complexes: [Cu(2)(L3-3)I](n) (1), [Cu(2)(L4-4)Br](n) (2-Br), [Cu(2)(L4-4)Cl](n) (2-Cl), [Cu(2)(L3-4)(CN)](n) (3), [Cu(2)(L3-3)(CN)](n) (4), [Cu(3)(L4-4)(CN)(2)](n) (5), {[Cu(2)(L4-4)Br](2)·CuBr}(n) (6-Br), {[Cu(2)(L4-4)Cl](2)·CuCl}(n) (6-Cl), [Cu(2)(L4-4)(SCN)](n) (7α-SCN), [Cu(2)(L4-4)(SCN)](n) (7β-SCN), and [Cu(2)(L4-4)(N(3))](n) (7α-N(3)). These structures are based on a series of isomeric pyridylpyrazole ligands, namely, 3,5-bis(3-pyridyl)-1H-pyrazole (HL3-3), 3-(3-pyridyl)-5-(4-pyridyl)-1H-pyrazole (HL3-4), and 3,5-bis(4-pyridyl)-1H-pyrazole (HL4-4), and their structural features range from 1-D (1), 2-D (2), and 3-D noninterpenetration (3), to 3-D 2-fold interpenetration (4 and 5), to 3-D self-catenation (6 and 7), exhibiting a trend from simple to complex with dimension expansion and an interpenetrating degree increase. The five most complex structures (6 and 7) with self-catenated networks are based on 2-fold interpenetrated networks linked via appropriate second ligating spacers (Cl(-), Br(-), SCN(-), and N(3)(-)), representing a strategy to construct self-catenated coordination polymers through cross-linking interpenetrated frameworks. Moreover, these complexes exhibit strong photoluminescence, which is mainly ascribed to Cu(I)-related charge transfers (MLCT, MC, and MMLCT) regulated by the electronic properties of halogen or pseudohalogen. The topological evolution and luminescence variation presented in this work open an avenue to understanding the luminescence origin and the structure-property relationship of luminescent coordination polymers.     

Tribenzotriquinacenes bearing six-fold benzofuran extensions: electron-rich C3v-symmetrical hosts for C60

New tribenzotriquinacene (TBTQ) hosts bearing six-fold peripheral benzofuran functionalization have been synthesized. The three polycondensed arene wings were shown to operate optically independently and to generate deeply bowl-shaped C(3v)-symmetrical frameworks that act as relatively weak hosts toward C(60), as revealed by (1)H NMR spectroscopy.