Jiying Men

Selective Epoxidation of Cyclohexene Catalyzed by New Bidentate Schiff Base Dioxomolybdenum(VI) Complex Immobilized on Crosslinked Polystyrene Microspheres

A new immobilized bidentate Schiff base dioxomolybdenum(VI) complex was prepared with chloromethlated crosslinked polystyrene (CMCPS) microspheres as starting carrier via two stepwise polymer reactions with p-hydroxybenzaldehyde and glycine as reagents, respectively, as well as a coordination reaction with MoO2(acac)2, and the immobilized dioxomolybdenum(VI) complex abbreviated to CPS-[MoO2(ALGL)2] (ALGL refers to the bidentate Schiff base ligand, which comes form aldehyde [AL] group and glycine [GL]) was used in the epoxidation reaction of cyclohexene with tert-butyl hydroperoxide (TBHP) as oxidant. In the epoxidation reaction of cyclohexene, this heterogeneous dioxomolybdenum(VI) complex catalyst has high catalytic activity and excellent catalytic selectivity.

Preparation of grafted microspheres CPVA-g-PSSS and studies on their drug-carrying and colon-specific drug delivery properties.

Sodium 4-styrene sulfonate (SSS) was graft-polymerized on the surfaces of crosslinked polyvinyl alcohol (CPVA) microspheres in a manner of surface-initiated graft-polymerization by using cerium salt-hydroxyl group redox initiation system, obtaining the grafted microspheres CPVA-g-PSSS. The chemical structure and physicochemical characters of CPVA-g-PSSS microspheres were fully characterized with infrared spectroscopy (FTIR), scanning electron microscopy (SEM) and zeta potential determination. The aim of this work is to constitute a novel colon-specific drug delivery system via molecular design by using CPVA-g-PSSS microspheres as the drug-carrying material and by taking metronidazole (MTZ) as the model drug. The drug-carrying ability and mechanism of the grafted microspheres CPVA-g-PSSS for MTZ were investigated. Finally, in-vitro release tests for the drug-carrying microspheres were conducted. The experimental results show that in an acidic medium, the grafted microspheres CPVA-g-PSSS exhibit strong adsorption ability for MTZ by driving of electrostatic interaction, and have an adsorption capacity of 112 mg/g, displaying the high efficiency of drug-carrying. The in-vitro release behavior of the drug-carried microspheres is highly pH-sensitive. In the medium of pH=1, the drug-carrying microspheres do not release the drug, whereas in the medium of pH=7.4, a sudden delivery phenomenon of the drug will occur, displaying an excellent colon-specific drug delivery behavior.

Preparation and characterization of 8-hydroxyquinoline-functionalized polysulfone and preliminary study on luminescence property of its complex with Al(III)

Abstract8-Hydroxyquinoline aluminum complex-attached polysulfone was prepared via a polymer reaction and a coordination reaction, namely 8-hydroxyquinoline aluminum functionalization of polysulfone (PSF) was realized. 5-chloromethyl-8-hydroxyquinoline (CHQ) was first prepared through the chloromethylation reaction between 8-hydroxyquinoline (HQ) and chloromethylation reagent 1,4-bichloromethoxy-butane (BCMB). A polymer reaction, Friedel-Crafts alkylation reaction, was carried out between PSF and CHQ in the presence of Lewis catalyst SnCl4, and HQ was bonded onto the side chains of PSF, obtaining the modified polysulfone HQ-PSF. Then, the coordination reaction between HQ-PSF and 8-hydroxyquinoline aluminum complex AlQ2, which had two HQ ligands, was conducted, and the luminescence material AlQ3-PSF, in whose molecular structure 8-hydroxyquinoline aluminum complex AlQ3 is attached chemically onto the side chains of PSF, was achieved, namely, the AlQ3-containing PSF was successfully prepared. The chemical structures of HQ-PSF and AlQ3-PSF were fully characterized by FTIR, 1H NMR and the UV/vis absorption spectrum, and the luminescence performance of AlQ3-PSF was initially examined. In this work, the 8-hydroxyquinoline functionalization process of PSF was mainly investigated. The effects of the key factors on the Friedel-Crafts alkylation reaction, which occurs on the side chains of PSF macromolecules, were mainly researched, and the reaction mechanism was explored. The experimental results show that the Friedel-Crafts alkylation reaction between PSF and CHQ can proceed smoothly, and the suitable reaction conditions are as follows: a temperature of 70 °C, with N,N-dimethylformamide (DMF) as solvent, and using SnCl4 as a Lewis catalyst. The AlQ3-containing polysulfone, AlQ3-PSF, possesses the fluorescence-emission spectrum of AlQ3, and its luminescence performance is nearly identical with AlQ3 under the same concentration condition of the AlQ3 unit.

Preparation of heparin-functionalized microspheres and study on their adsorption characteristic for basic protein lysozyme

In suspension polymerization system, poly(glycidyl methacrylate) (PGMA) microspheres are firstly prepared. Then, ring opening reaction takes place when heparin is bonded on PGMA microspheres to obtain functional PGMA-heparin microspheres. The chemical structure and physicochemical characters of PGMA-heparin microspheres are fully characterized with infrared spectroscopy (FTIR), scanning electron microscopy (SEM) and zeta potential determination. The adsorption properties of PGMA-heparin for lysozyme are mainly investigated. The effects of the main factors on the adsorption properties are explored, furthermore the adsorption mechanism is analyzed in depth, and the adsorption thermodynamics is also researched. The experimental results show that the strong electrostatic interaction is formed between high density of negative charge coming from the carboxyl groups or sulfonic acid groups of heparin and the positive charge of basic protein lysozyme. The adsorption of PGMA-heparin for lysozyme is dependent on the pH value of the medium, and the saturated adsorption amount of PGMA-heparin for lysozyme possesses a maximum at pH 8, which reaches up to 654 mg/g. The adsorption of PGMA-heparin for lysozyme is an exothermic process which is driven by entropy, and the adsorption amount decreases with increasing the temperature.

Preparation and Characterization of Metronidazole-Surface Imprinted Microspheres MIP-PSSS/CPVA for Colon-Specific Drug Delivery System

In this paper, the use of molecular surface imprinted polymers (MIPs) in designing colon-specific drug delivery systems was investigated. MIPs were prepared on crosslinked polyvinyl alcohol microspheres (CPVA) with sodium 4-styrene sulfonate (SSS) as functional monomer, Metronidazole (MTZ) as template and N,N’-Methylene bisacrylamide (MBA) as crosslinking agent by utilizing cerium salt-hydroxyl group redox initiation system, obtaining MTZ molecular surface imprinted microspheres MIP-PSSS/CPVA. The MIP-PSSS/CPVA microspheres were further characterized by scanning electron microscope and batch binding method. Because there is strong electrostatic interactions between MTZ and monomer SSS, the MTZ molecular surface imprinting is quite successful, and the imprinted microspheres MIP-PSSS/CPVA possess high recognition selectivity and excellent combining affinity. The experimental results show that at pH 1, the MIP-PSSS/CPVA microspheres exhibit very strong binding ability for MTZ, and the binding capacity reaches up to 115 mg/g. The in vitro release of the MTZ-loaded MIP-PSSS/CPVA is highly pH-dependent and time-delayed. The release behavior shows that the drugs do not release in simulated gastric fluid (pH = 1), the drug release is small while in the simulated small intestinal fluid (pH = 6.8), an abrupt release will be firstly produced and then drug release is sustained and slowed in the simulated colon fluid (pH = 7.4), displaying excellent colon-specific drug delivery behavior.