Total synthesis of isoprekinamycin: structural evidence for enhanced diazonium ion character and growth inhibitory activity toward cancer cells

The structurally novel diazobenzo[a]fluorene antibiotic isoprekinamycin (IPK) has been synthesized for the first time employing a Suzuki coupling of a brominated AB ring synthon with a boronate ester representing the D ring, followed by anionic cyclization and appropriate functional group manipulations. The first indication that the diazobenzo[a]fluorene system exhibits in vitro anticancer activity is provided and X-ray crystallographic evidence for enhancement of diazonium ion character as a consequence of intramolecular H-bonding is described.     

'Living' controlled in situ gelling systems: thiol-disulfide exchange method toward tailor-made biodegradable hydrogels

A 'living' controlled hydrogel formation method was first reported to create loose and compact in situ biodegradable hydrogels. The method executed under mild reaction conditions can conveniently tailor the hydrogel properties, and it has the potential to develop into a powerful tool for the design, synthesis, and self-assembly of novel tailor-made biomaterials and drug delivery systems.     

Quantitative determination of glutathione in single human erythrocytes by capillary zone electrophoresis with electrochemical detection

Glutathione (GSH) in single human erythrocytes is determined by capillary zone electrophoresis with end-column amperometric detection at a gold/mercury amalgam microelectrode. A capillary of 10 microm inner diameter is suitable for determination of GSH in an individual erythrocyte with a good signal-to-noise ratio. The limit of detection is 1 x 10(-7) mol/L or 26 amol and the linear dynamic range is 2 x 10(-7) to 2 X 10(-5) mol/L for the capillary. In this method, the calibration line is obtained with a capillary adsorbed before a certain amount of hemoglobin can be used for the quantification of GSH in the external standardization. The whole cell injection and the lack of necessity of a derivatization reaction lead to more accurate and precise results, which are closer to the macroscopic values of glutathione in human red blood cell (i.e., hemolysate) than those determined by indirect laser-induced fluorescence detection.     

Patterned growth of vertically aligned ZnO nanowire arrays on inorganic substrates at low temperature without catalyst

We report an approach for growing aligned ZnO nanowire arrays with a high degree control over size, orientation, dimensionality, uniformity, and possibly shape. Our method combines e-beam lithography and a low temperature hydrothermal method to achieve patterned and aligned growth of ZnO NWs at <100degreesC on general inorganic substrates, such as Si and GaN, without using catalyst. This approach opens up the possibility of applying ZnO nanowires as sensor arrays, piezoelectric antenna arrays, two-dimensional photonic crystals, IC interconnects, and nanogenerators.     

An interesting molecular-assembly of β-cyclodextrin pipelines with embedded hydrophilic nickel maleonitriledithiolate

A unique tubular molecular-assembly, constructed by β-cyclodextrin and Na[Ni(mnt)(2)], was identified by X-ray crystallography. Inclusion complex Na[Ni(mnt)(2)]@β-cyclodextrin (1) crystallized in space group P2(1)2(1)2 as hydrated head-to-head, tail-to-tail, and head-to-tail host pipelines with negatively charged [Ni(mnt)(2)](-) guests included, exhibiting a 3?:?1 (host?:?guest) stoichiometry. The hydrophilic transition-metal coordination compound (Na[Ni(mnt)(2)]) was embedded within a hydrophobic cyclodextrin cavity, which resulted in a β-cyclodextrin trimer motif and one-third "empty" host packing model in the crystal. Induced circular dichroism (ICD) spectra of inclusion complex 1 was investigated, which indicated the same penetration pattern of the guests in host cavities in solution phase as that discovered in the crystal structure. In addition, PM3 quantum chemistry calculations strongly supported the co-conformational alignments of inclusion complex 1 that was identified in the crystal as well as in the solution.     

Chamaejasmine inactivates Akt to trigger apoptosis in human HEp-2 larynx carcinoma cells

In the present study, we investigated the mechanisms of chamaejasmine action on human HEp-2 larynx carcinoma cells, which possess constitutively active Akt. Results indicated that chamaejasmine showed more notable anticancer activity than apigenin against HEp-2, PC-3, NCI-H1975, HT-29 and SKOV-3. Moreover, chamaejasmine presented most significantly inhibition towards HEp-2, with IC?? values of 1.92 μM. Treatment of HEp-2 cells with chamaejasmine (1-4 μM) resulted in signi?cant dose-dependent decrease in Akt phosphorylation at Serine473. Chamaejasmine-mediated dephosphorylation of Akt resulted in inhibition of its kinase activity, which was con?rmed by reduced phosphorylation of proapoptotic proteins BAD and glycogen synthase kinase-3, essential downstream targets of Akt. Inactivation of Akt seems to be associated with downregulation of insulin-like growth factor receptor 1 protein level and inhibition of its autophosphorylation upon chamaejasmine treatment. Exposure to chamaejasmine signi?cantly induced caspase-9 and caspase-3 activity. In vivo, chamaejasmine intake through gavage resulted in inactivation of Akt and induction of apoptosis in HEp-2 tumors. These results suggest that Akt inactivation and dephosphorylation of BAD is a critical event, at least in part, in chamaejasmine-induced HEp-2 cells apoptosis.     

Synthesis, spectroscopic characterization and reactivities of linear and butterfly chromium/selenium complexes containing substituted cyclopentadienyl ligands: crystal structures of [{η-MeC5H4Cr(CO)2}2Se] and [{η-EtO2CC5H4Cr(CO)2}2Se2]

The Cr-Cr singly-bonded dimers [{η⁵-RC₅H₄Cr(CO)₃}₂] (1, R=Me; 2, R=CO₂Et) reacted with an equivalent of elemental selenium in THF at room temperature to give the linear Cr₂Se complexes [{η⁵-RC₅H₄Cr(CO)₂}₂Se] (3, R=Me; 4, R=CO₂Et), whereas the linear Cr₂Se complex (5, R=MeCO) reacted with excess NaBH₄, Ph₃PCHPh or 2,4-dinitrophenylhydrazine under respective conditions to afford the linear Cr₂Se derivatives [{η⁵-RC₅H₄Cr(CO)₂}₂Se] (6, R=MeCH(OH); 7, R=PhCHCMe; 8, R=2,4-(NO₂)₂C₆H₃NHNCMe). Similarly, while the butterfly Cr₂Se₂ complexes [{η⁵-RC₅H₄Cr(CO)₂}₂Se₂] (9, R=Me; 10, R=CO₂Et) could be produced either by reaction of dimers 1 and 2 with an excess amount of elemental selenium, or by reaction of the linear complexes 3 and 4 with an equivalent of elemental selenium, the butterfly Cr₂Se₂ derivatives [{η⁵-RC₅H₄Cr(CO)₂}₂Se₂] (12, R=MeCH(OH); 13, R=PhCHCMe; 14, R=2,4-(NO₂)₂C₆H₃NHNCMe) were yielded by reaction of the butterfly Cr₂Se₂ complex (11, R=MeCO) with an excess quantity of NaBH₄, Ph₃PCHPh and 2,4-dinitrophenylhyazine. Both the linear complexes 3, 4, 6-8 and the butterfly complexes 9, 10, 12-14 are new, which have been fully characterized by elemental analysis, spectroscopy and X-ray crystallography.     

聚合物在碳纤维表面的电沉积

用电沉积方法将苯乙烯-马来酸酐、乙酸乙烯酯-马来酸酐、甲基丙烯酸甲酯-马来酸酐共聚物沉积于碳纤维表面。通过实验初步证实了此过程的负离子-自由基机理,以及沉积层在纤维表面的物理粘附。由于电沉积的聚合物中间层改善了碳纤维增强塑料中纤维-基体树脂间的界面粘接作用,使原来的剪切破坏基本上发生于界面的情况转变成发生于基体本身为主。并将单向碳纤维增强环氧树脂复合材料的层间剪切强度,由原来的600kg/cm~2左右提高到1000kg/cm~2以上,经沸水浸泡100小时后的强度损失也减少了。     

Production and Characterization of Polyclonal and Monoclonal Abs Against the RNA-Binding Protein QKI

RNA-binding protein QKI, a member of the Signal Transduction and Activation of RNA family, is found to be essential in the blood vessel development and postnatal myelination in central nervous system (Woo et al., Oncogene 28:1176–1186, 2009; Lu et al., Nucleic Acids Res 31(15):4616–4624, 2003; Bohnsack et al., Genesis 44(2):93–104, 2006). However, its wide expression pattern suggests other fundamental roles in vivo (Kondo et al., Mamm Genome 10(7):662–669, 1999). To facilitate the understanding of QKI function in various systems, we prepared the polyclonal and monoclonal antibodies against QKI. To obtain the antigen, recombinant His-tagged QKI was expressed in Escherichia coli and highly purified by Ni²⁺-chelated column combined with hydrophobic and ion exchange methods. Following three types of immunizations with different adjuvants, including Freund’s, PAGE gel, and nitrocellulose membrane, only the antiserum produced with Freund’s adjuvant is effective for Western blot detection. Several McAb clones are able to recognize both endogenous and over-expressed QKI with high affinity in Western blot and immunofluorescence. The specificity of Ab was validated as weakening, and no specific signals were observed in cells with QKI knocking down. Immunohistochemistry analysis further showed positive staining of QKI in kidney where QKI mRNA was abundantly expressed, ensuring the wide applications of the QKI Abs in the ongoing mechanistic studies.     

Graphene as a spacer to layer-by-layer assemble electrochemically functionalized nanostructures for molecular bioelectronic devices

This study demonstrates the capability of graphene as a spacer to form electrochemically functionalized multilayered nanostructures onto electrodes in a controllable manner through layer-by-layer (LBL) chemistry. Methylene green (MG) and positively charged methylimidazolium-functionalized multiwalled carbon nanotubes (MWNTs) were used as examples of electroactive species and electrochemically useful components for the assembly, respectively. By using graphene as the spacer, the multilayered nanostructures of graphene/MG and graphene/MWNT could be readily formed onto electrodes with the LBL method on the basis of the electrostatic and/or π-π interaction(s) between graphene and the electrochemically useful components. Scanning electron microscopy (SEM), ultraviolet-visible spectroscopy (UV-vis), and cyclic voltammetry (CV) were used to characterize the assembly processes, and the results revealed that nanostructure assembly was uniform and effective with graphene as the spacer. Electrochemical studies demonstrate that the assembled nanostructures possess excellent electrochemical properties and electrocatalytic activity toward the oxidation of NADH and could thus be used as electronic transducers for bioelectronic devices. This potential was further demonstrated by using an alcohol dehydrogenase-based electrochemical biosensor and glucose dehydrogenase-based glucose/O(2) biofuel cell as typical examples. This study offers a simple route to the controllable formation of graphene-based electrochemically functionalized nanostructures that can be used for the development of molecular bioelectronic devices such as biosensors and biofuel cells.