An automated detection of influenza virus based on 3-D magnetophoretic separation and magnetic label.

Automated detection of the influenza virus is important for the prevention of infectious viruses. Herein, assisted by three-dimensional (3-D) magnetophoretic separation and magnetic label, an automated detection device was constructed for H7N9 influenza virus hemagglutinin. Multi-layer glass slides were used to generate a 3-D microchannel network with two-level channels, realizing 3-D magnetophoretic separation with a magnetic field in the vertical direction to microchannels for the sample treatment. After the immunomagnetic separation, a magnetic-tagged complex was captured in an antibody-modified glass capillary, where magnetic beads further as a label could cause the voltage change of the miniature tube liquid sensor to obtain the detection signal. Moreover, the whole detection process and detection results were controlled and read through a liquid crystal display (LCD) screen to improve the automation. Finally, the detection limit was calculated to be 8.4 ng mL-1 for H7N9 hemagglutinin and had good specificity and reproducibility. These results indicate that this detection device proposes promising automated avenues for the early detection of infectious diseases.

Improved solubility and stability of 7-hydroxy-4-methylcoumarin at different temperatures and pH values through complexation with sulfobutyl ether-ß-cyclodextrin.

The inclusion complex of 7-hydroxy-4-methylcoumarin (7H4MC) with sulfobutyl ether-ß-cyclodextrin (SBE-ß-CD) was investigated by means of UV-vis, circular dichroism and (1)H NMR spectroscopy in phosphate buffer solutions at different temperatures and pH values. The stoichiometric ratio of the complexation was found to be 1:1 and the stability constants (KC) were estimated from phase solubility analysis. The thermodynamic parameters of standard Gibbs free energy change, ΔG(o), enthalpy change, ΔH(o), and entropy change, ΔS(o), for the complexation process were obtained by using the van't Hoff equation and Gibbs-Helmholtz equation. The large negative ΔH(o) and the small negative or positive ΔS(o) (|ΔH(o)|>|TΔS(o)|) demonstrated that the inclusion interaction was an enthalpy-driven process. The positive signal of circular dichroism indicated that 7H4MC penetrated the cavity in such a way that the transition moment of the guest chromophore was parallel to the long axis of SBE-ß-CD cavity. Moreover, the (1)H NMR spectrum showed that the entire 7H4MC molecule, except the hydroxyl group, was included in the SBE-ß-CD cavity.

Effect of pH on the complexation of kaempferol-4'-glucoside with three ß-cyclodextrin derivatives: isothermal titration calorimetry and spectroscopy study.

The utilization of kaempferol and its glycosides in food and pharmaceutical industries could be improved by the formation of inclusion complexes with cyclodextrins at different pH. This study explores the complexation of kaempferol-4'-glucoside with sulfobutyl ether-ß-cyclodextrin (SBE-ß-CD), hydroxypropyl-ß-cyclodextrin (HP-ß-CD), and methylated-ß-cyclodextrin (M-ß-CD) in phosphate buffer solutions of different pH using isothermal titration calorimetry, UV-vis absorption and proton nuclear magnetic resonance spectroscopy at 298.2 K. Experimental results showed that kaempferol-4'-glucoside binds with the three ß- cyclodextrins in the same 1:1 stoichiometry. The rank order of stability constants is SBE-ß-CD > HP-ß-CD > M-ß-CD at the same pH level and pH 6.0 > pH 7.4 > pH 9.0 for the same cyclodextrin. The binding of kaempferol-4'-glucoside with the three ß-cyclodextrin derivatives is synergistically driven by enthalpy and entropy at pH 6.0 and enthalpy-driven at pH 7.4 and 9.0. The possible inclusion mode was that in the cavity of ß-CD is included the planar benzopyranic-4-one part of the kaempferol-4'-glucoside.

Inclusion complexes of quercetin with three ß-cyclodextrins derivatives at physiological pH: spectroscopic study and antioxidant activity.

Properties of the inclusion complexes of quercetin (QUE) with sulfobutyl ether-ß-cyclodextrin (SBE-ß-CD), hydroxypropyl-ß-cyclodextrin (HP-ß-CD), and methylated-ß-cyclodextrin (M-ß-CD) in tris-HCl buffer solutions of pH 7.40 were investigated. The stoichiometry and thermodynamic parameters for the complexation process (stability constants K, Gibbs free energy change ΔG, enthalpy change ΔH and entropy change ΔS) were determined using phase-solubility and fluorescence spectra analysis. The thermodynamic studies indicated that the inclusion reactions between QUE and the three ß-CDs are enthalpy-driven processes. Proton nuclear magnetic resonance spectroscopy indicated that B-ring, C-ring, and part of A-ring of QUE interact with the cavity of ß-CDs. The antioxidant activity of QUE and its inclusion complexes were determined by the scavenging of stable radical DPPH(*). The results showed that the complexed QUE/CDs were more effective than free QUE, with the QUE/SBE-ß-CD complex as the best form.