A microchip-based proteolytic digestion system driven by electroosmotic pumping

Microchip-based proteomic analysis requires proteolytic digestion of proteins in microdevices. Enzyme reactors in microdevices, fabricated in glass, silicon, and PDMS substrates, have recently been demonstrated for model protein digestions. The common approach used for these enzyme reactors is employment of a syringe pump(s) to generate hydrodynamic flow, driving the proteins through the reactors. Here we present a novel approach, using electroosmotic flow (EOF) to electrokinetically pump proteins through a proteolytic system. The existence of EOF in the proteolytic system packed with immobilized trypsin gel beads was proven by imaging the movement of a neutral fluorescent marker. Digestions of proteins were subsequently carried out for 12 min, and the tryptic peptides were analyzed independently using capillary electrophoresis (CE) and MALDI-TOF mass spectrometry (MS). The results from CE analysis of the tryptic peptides from the EOF-driven proteolytic system and a conventional water bath digestion were comparable. MALDI-TOF MS was used to identify the parent protein and the tryptic peptides using MS-Fit database searching. The potential utility of the EOF-driven proteolytic system was demonstrated by direct electro-elution of proteins from an acrylamide gel into the proteolytic system, with elution and tryptic digestion achieved in a single step. The EOF-driven proteolytic system, thus, provides a simple way to integrate protein digestion into an electrophoretic micro total analysis system for protein analysis and characterization.     

Effects of ultraviolet B on epidermal morphology, shedding, lipid peroxide, and antioxidant enzymes in Cope's rat snake (Elaphe taeniura)

Cope's rat snakes (Elaphe taeniura) favor to expose under sunlight in order to increase their body temperature simultaneously increasing the risk of skin damage by ultraviolet B (UVB) irradiation. We have investigated the effects of UVB irradiation on their skin. Results show that the UVB transmission of the keratinous layer was only 5.1+/-0.36%. The peak of epidermal damage and malondialdehyde (MDA) content, a product of lipid peroxidation, simultaneously occurred 72-96, 48 or 24 h after exposure to 300, 500 and 800 mJ/cm2 of UVB radiation, respectively. Superoxide dismutase (SOD) activity was inhibited by UVB and the lowest activity occurred 24, 48, 12 and 12 h after exposure to 110, 300, 500 and 800 mJ/cm2 of UVB, respectively. SOD activity recovered later to some extent but mostly remained below control level. After exposure to different doses of UVB radiation, catalase (CAT) activity was inhibited immediately, and then gradually recovered and even increased to peak levels above control level. The highest CAT levels accompanied the most serious damage of skin morphology. Later on, CAT activity decreased and recovered again close to or below control level, which was accompanied by shedding off the damaged epidermal complex. This indicated that the epidermal damage induced by UVB is closely related to lipid peroxidation, where CAT acts as a primary antioxidant enzyme. Moreover, the keratinous layer protects the viable cell layer against UVB damage as well.     

Synthesis of a highly hindered hydrindanone via alpha-carbonyl radical cyclization: enantiospecific formal syntheses of (-)-pinguisenol and (-)-alpha-pinguisene

An enantiospecific synthesis of Schinzer's ketone 3 from (R)-(+)-pulegone via alpha-carbonyl radical cyclization was accomplished. This work also constitutes an enantiospecific formal syntheses of (-)-pinguisenol and (-)-alpha-pinguisene. The intermediate ketone 4 would be useful for the synthesis of other pinguisane-type sesquiterpenes.     

The first mu3-oxalato-bridged copper complex with tridentate Schiff base ligand N-ethyl-N'-salicylidene-1,2-diaminoethane: synthesis,structure, and magnetic properties

The first mu(3)-oxalato-bridged copper(II) complex, [[Cu(3)(L)(3)(mu(3)-C(2)O(4))][Cu(L)(H(2)O)](ClO(4))(2)] x 0.5(H(2)O) x 0.5(CH(3)OH), where HL = N-ethyl-N'-salicylidene-1,2-diaminoethane, has been synthesized and characterized by variable-temperature magnetic susceptibility measurement. The complex exhibits ferromagnetic coupling between the oxalato-bridged copper atoms and antiferromagnetic coupling between the oxygen-bridged copper atoms.     

Excited-state metal-to-ligand charge transfer dynamics of a ruthenium(II) dye in solution and adsorbed on TiO2 nanoparticles from resonance Raman spectroscopy

The dynamics of metal-to-ligand charge transfer (MLCT) in a cis-bis(4,4'-dicarboxy-2,2'-bipyridine)-bis(isothiocyanato)ruthenium(II) dye (N3) are compared for the free dye in solution and the dye adsorbed on the surface of the TiO(2) nanoparticles from resonance Raman spectroscopy. The 544-nm MLCT absorption band of N3 adsorbed on TiO(2) is slightly blue-shifted from that of the free N3, indicating a weak electronic coupling between N3 and TiO(2). The resonance Raman spectra of N3 and the N3|TiO(2) complex obtained upon excitation within the lowest-lying MLCT singlet state of the dye are similar except for slight shifts in band positions. Resonance Raman cross sections have been obtained for the vibrational modes of both N3 and N3|TiO(2) with excitation frequencies spanning the 544-nm MLCT band. Self-consistent analysis of the resulting resonance Raman excitation profiles and absorption spectrum using a time-dependent wave packet formalism over two electronic states yields mode-specific vibrational and solvent reorganization energies. Despite the weak electronic coupling between N3 and TiO(2) in N3|TiO(2), adsorption strongly affects the reorganization energies of N3 in the intramolecular MLCT state. Adsorption of N3 onto TiO(2) increases the absolute Raman cross section of each mode by a factor of ca. 1.6 and decreases the vibrational and solvent reorganization energies by factors of 2 and 6, respectively. The excited-state dynamics of N3 adsorbed on the surface of TiO(2) nanoparticles were observed to be independent of the number of N3 molecules adsorbed per TiO(2) nanoparticle. The effect of TiO(2) on the dynamics of the adsorbed N3 is primarily due to both mode-specific vibrational and electronic pure dephasing, with the dominant contribution from the latter process.     

Alkaloids from Juglans Mandshurica maxim induce distinctive cell death in hepatocellular carcinoma cells

The aim of this work was to further investigate the anticancer potential of Juglans mandshurica Maxim, including the separation of active constituents and their anti-proliferative effects with underlying mechanism of action. Five alkaloids (1–5) were isolated from the bark of J. mandshurica. Among them, 1 showed the highest cytotoxic activities against Hep3B and HepG2 cells with an IC50 values of 61.80 and 56.24 μM, respectively. Therefore, the cellular mechanism involved 1 was subsequently studied. Our results showed that 1 markedly caused apoptosis and autophagy, but without cell cycle arrest in HepG2 cells. Interestingly, only autophagic cell death was induced in 1-treated Hep3B cells. It is concluded that the isolated alkaloids exerted a certain anti-hepatoma potential, and our results may provide a basis for the further investigation of the alkaloids extracted from J. mandshurica.     

Semi-interpenetrating polymer networks toward sulfonated poly(ether ether ketone) membranes for high concentration direct methanol fuel cell

Semi-IPNs were constructed by forming the crosslinking networks via the reaction between BPPO and diamine cross-linkers to overcome the dimensional swelling and methanol-permeation issues of SPEEK.     

CuCl_2/离子液体催化炔丙醇、仲胺与CO_2的三组分反应

以二氧化碳代替传统剧毒的光气等来合成氨基甲酸酯已成为研究的热点,然而现存的体系普遍需要高温高压等苛刻反应条件才能催化反应,并且很少有催化体系能够有效地回收和再利用.探索了将CuCl_2/离子液体(IL)用于炔丙醇、仲胺和CO_2的三组分反应合成β-羰基氨基甲酸酯.在常压、45℃的温和条件下,以较低催化当量(2%摩尔分数)的廉价易得的2价铜将多种类型的炔丙醇和仲胺通过简单的"一锅法"合成相应的目标化合物,并且循环利用3次后产率并未见明显下降.分步反应结合NMR监测的机理实验证明,炔丙醇与CO_2先生成的α-亚甲基环碳酸酯是反应的重要中间体,且醋酸型离子液体对炔丙醇和CO_2的活化具有重要作用.     

Intercalation assembly of kojic acid into Zn-Ti layered double hydroxide with antibacterial and whitening performances

The inhibitor of melanin and the bacteriostatic agent kojic acid was inserted into Zn-Ti layered double hydroxide (LDH) by anion-exchange reaction. The structure, slow release, antibacterial and skin whitening activity were studied.     

静电纺丝法制备复合纳米材料

经由溶胶-凝胶法过程,应用静电纺丝机原理,以聚乙烯醇(PVA)和无机盐(LiMn2O4)为前驱物,制备出了含有LiMn2O4无机组分的复合纳米纤维,为复合无机纳米纤维的制备方式供给了一条新的思路。实验中系统地研究了PVA的浓度对其所形成的纤维描摹特征的影响。PVA水溶液用于纺丝的最好质量分数约为8.0%。在实验过程中,随着PVA质量分数的渐渐增加,其所形成纤维的直径也随之渐渐增大,而溶液的黏度也在逐步增大,这就使得溶剂挥发变得越来越难,小液珠的表面难以构成理想的“泰勒锥”,电压过小,样品溶液无法纺丝,在针头处成水滴状落在针头下方。电压过大则会在纤维丝上呈现念珠形态,阻碍样品电纺时的形貌。实验表明,在施加18kV的高电压,默认机器的其它设定条件下,依托不同质量分数的PVA溶液可制备出三种不同的纤维。