Theoretical Studies on the Structures of Metal String Complexes Crn(L)4Cl2 (n = 3, 5, 7; L = Oligo-α-Pyridylamide) under the Effect of an Electric Field.

To study the electronic structures and properties of [Crn(L)4Cl2] (n = 3, L = dpa: di(2-pyridyl)amido; n = 5, L = tpda: tripyridyldiamido; n = 7, L = teptra: tetrapyridyltriamine) metal string complexes, the BP86 method was used by considering the influence of the electric field (EF) applied parallel to the metal axis. As the EF increases, the migration of more positively charged Crodd is more significant than that of Creven, which results in alternating long-short Cr-Cr bonds. This happens because of the natural charges on the Crodd of 1-3, which are more electropositive than those on Creven. The electrons are pulled to the Cr and Cl(r) atoms at the high-potential side from Cl(l) at the low-potential side by the EF, which leads to asymmetrical FMOs. After the critical electric field (Ec), the configuration turns into a remarkably asymmetric one with alternating Cr-Cr quadruple bonds and weak interactions. The electrons are transferred from equatorial ligands (L) to metal chains. In the meantime, the asymmetry of the FMOs increases and the delocalization is further reduced, which affects the conductivity. Especially for [Cr7(teptra)4Cl2], the delocalized electrons of HOMO are completely transformed into a localized model after the critical electric field. It is observed that this supports the electric switching phenomenon ascribed to the conformations of delocalized and localized electrons. In addition, the longer the length of the metal chain, the smaller the Ec and the easier is for the complexes to be polarized by the EF.

Simultaneous determination of five triterpene acids in rat plasma by liquid chromatography-mass spectrometry and its application in pharmacokinetic study after oral administration of Folium Eriobotryae effective fraction.

Folium Eriobotryae effective fraction (FEA), the extract of Folium Eriobotryae, had been used as anti-hyperglycemia and anti-hyperlipemia medicine in China. A previous study indicated that euscaphic acid, maslinic acid, corosolic acid, oleanolic acid and ursolic acid, the five structurally similar triterpene acids (containing two groups of structural isomers), are the major components of FEA. In the present study, we developed a specific and reliable LC-MS method for simultaneous determination of the five triterpene acids in rat plasma, and further investigated their pharmacokinetic properties after oral administration of FEA. Following a simple sample preparation, chromatographic separation was achieved on a C18 column with a mobile phase composed of methanol-0.1% ammonium acetate (80:20, v/v). Quantification was achieved by monitoring the selected ions at m/z 487.6 for euscaphic acid, m/z 471.5 for maslinic acid and corosolic acid, m/z 455.5 for oleanolic acid and ursolic acid and m/z 469.5 for internal standard. The method was validated to be specific, accurate and precise over the concentration ranges of 10-3000 ng/mL with limits of detections of 5 ng/mL for the five triterpene acids. Finally, the method was successfully applied to the pharmacokinetic study of the five structurally similar triterpene acids in rats after oral administration of FEA.

[Preparation of solid dispersion of triterpenoid acids from Eriobotrya japonica leaf and study on their dissolution in vitro].

UNLABELLED: To prepare the solid dispersion of Eriobotrya japonica leaf triterpenoid acids(EJA) in order to enhance their dissolution characteristics in vitro. METHODS: Taking ursolic acid and oleanolic acid in vitro dissolution as an indicator, the influence of factors including different water-soluble carriers (PEG 6000, PVPk30 and P188) and the drug/carrier weight ratio for the preparation of solid dispersion were examined using single factor experiment. Differential scanning calorimetry (DSC) and X-ray diffraction (X-RD) were used to describe the characterization of solid dispersion. RESULTS: P188 was used as appropriate carrier for the preparation of solid dispersion and the drug/carrier weight ratio was 1:5. The X-RD and DSC showed EJA existed in the solid dispersion as the way of amorphous. The dissolution rate of EJA solid dispersion was significantly higher than physical mixture and EJA. CONCLUSION: The solid dispersion prepared with P188 can significantly increase the solubility and dissolution of EJA in vitro. This study provides the scientific evidence for further preparation of solid dispersion tablet.

Fabrication of surface charge pH-sensitive multi-bumpy small magnetic bead with ultrahigh magnetic content and its ultrahigh loading capacity and salt-free rapid isolation for DNA.

Gene transfection vector polyethyleneimine (PEI) was used as a cross-linking agent to crosslink the surface epoxidized magnetic nanoparticles and aggregate them to form a small magnetic bead (MB) with multiple nanoscale bumps on its surface (i.e. the multi-bumpy small magnetic bead, mbsMB). As there is a very low content of non-magnetic components (the cross-linking agent) in the magnetic bead, the mbsMB has an ultrahigh magnetic content of 81.95 % and a smaller particle size of 1.4 µm when compared with the usual medical MB. Such a small MB also has a strong magnetic force allowing it to reach the rapid separating ability of the commonly used larger medical MB which has 8 times its volume. The mbsMB has an obvious pH sensitivity of positive and negative surface charges and the salt-free isolation of DNA has been achieved based on the electrostatic interactions between mbsMB and DNA. This avoids the desalting of the isolated DNA as well as the effects of high salt concentration on its long chain helix structure. Whether in an acidic absorbing medium, an alkalinous desorbing one or a near neutral particle-storing one, the mbsMB will have obvious surface electrostatic charges. There is also its good suspension stability in an aqueous medium which provides a good condition for isolating of DNA suitable for efficiently adsorbing and desorbing. The as-prepared MB has a unique surface structure and some excellent properties, all suitable for adsorbing DNA. In addition, a large amount of commonly used gene transfection vector PEI can be cross-linked and bonded on the surface of mbsMB, whilst still having an excellent DNA-loading ability. In summary, the mbsMB has an ultrahigh capacity of 629.49 mg/g for DNA load.

Polyelectrolyte-protected Dual-color-quantum-dot Assembled Silica Nanoparticles and Their Application in Simultaneous Fluorescence Determination of e Antigen and Surface Antigen of Hepatitis B.

Cationic poly-diallyldimethylammonium (PDADMAC), green CdTe quantum dots (QDs) or red CdS coated CdTe QDs, and anionic polyacrylic acid (PAA) were respectively assembled on the nano-carrier SiO2 to prepare green fluorescence composite nanoparticles (GF-QDs) and red ones (RF-QDs) with the structure SiO2/PDADMAC/QD/PDADMAC/PAA. The sandwich structure "PDADMAC/QD/PDADMAC" on the nano-carrier not only realized the protection to fluorescence of QDs but also avoided the fluorescence shielding of silica shell for the assembled QDs. In 7 days, the diluent solutions of GF-QD and RF-QD all have a very stable fluorescence. On the contrary, the fluorescence of diluent solutions of red and green QDs reduced by 75.99 and 94.35%, respectively. Indeed, they have not fluorescent shielding and have a very slight fluorescent enhancement. Based on GF-QD and RF-QD, the simultaneous determination of Hepatitis B e antigen and surface antigen has been established. Their determination in buffer and plasma all showed good precision and accuracy.

Modulation of cholesterol transport by maternal hypercholesterolemia in human full-term placenta.

The significance of maternal cholesterol transporting to the fetus under normal as well as pathological circumstances is less understood. The objective of this study was to observe the effects of maternal hypercholesterolemia on placental cholesterol transportation. Human full-time placenta, maternal and venous cord blood were sampled at delivery from the pregnant women with serum total cholesterol (TC) concentrations at third trimester higher than 7.25 mM (n = 19) and the pregnant women with normal TC concentrations (n = 19). Serum lipids and expression of genes related to cholesterol transportation were measured by western blot or real-time PCR. The results indicated that serum TC, high density lipoprotein cholesterol (HDL-C), and low density lipoprotein cholesterol (LDL-C) levels were significantly increased, in pregnancies, but decreased in cord blood in hypercholesterolemic group compared to the matched control group. All the subjects were no-drinking, non-smoker, and gestational disease free. The mRNA expression of lipoprotein receptors, including LDLR and VLDLR were significantly increased, while the protein expression of PCSK9 was significantly increased in hypercholesterolemic placenta. In conclusion, maternal hypercholesterolemia might decrease the transportation of cholesterol from mother to fetus because of the high levels of PCSK9 protein expression.

Condensation and salt-induced decondensation of DNA upon incorporation of a V-shaped luminescent [Ru2(bpy)4(mbpibH2)](4+).

This paper first reports on the condensation of DNA to a tightly packed state induced by a V-shaped di-ruthenium(II) complex [Ru2(bpy)4(mbpibH2)]Cl4 (bpy=2,2'-bipyridine and mbpibH2=1,3-bis([1,10]phenanthroline[5,6-d]imidazol-2-yl)benzene), which binds to the groove of herring sperm DNA (hsDNA) with the binding constant of 2.0×10(7)M(-1) (0.05M NaCl, pH7.2). The di-Ru(II) complex is found to induce the condensation of both hsDNA to long chain-like particle clusters and originally circular plasmid pBR322 DNA to particulate structure under neutral conditions. More interestingly, the presence of NaCl has a significant impact on the condensation and decondensation of DNA upon incorporation of [Ru2(bpy)4(mbpibH2)](4+), representing tunable luminescence characteristics by NaCl. High salt concentration facilitates the decondensation of DNA-[Ru2(bpy)4(mbpibH2)](4+) adducts. The results from this study offer an effective method to control the condensation and decondensation of DNA upon incorporation of luminescent concentrators.