Huifang Xing

Synthesis of PGMA Microspheres with Amino Groups for High-capacity Adsorption of Cr(VI) by Cerium Initiated Graft Polymerization

A novel polyglycidylmethacrylate (PGMA) microspheres with high adsorption capacity of Cr(VI) was prepared by cerium(IV) initiated graft polymerization of tentacle-type polymer chains with amino group on polymer microspheres with hydroxyl groups. The micron-sized PGMA microspheres were prepared by a dispersion polymerization method and subsequently modified by ring-opening reaction to introduce functional hydroxyl groups. The polymer microspheres were characterized by scanning electron microscopy (SEM) and Fourier transform infrared spectroscopy (FTIR). The results indicated that the polymer microspheres had an average diameter of 5 mu m with uniform size distribution. The free amino group content was determined to be 5.13 mmol.g(-1) for g-PGMA-NH2 microspheres by potentiometric and conductometric titration methods. The Cr(VI) adsorption results indicated that the graft polymerization of tentacle-type polymer chains on the polymer microspheres could produce adsorbents with high adsorption capacity (500 mg.g(-1)). The polymer microsphcres with grafted tentacle polymer chains have potential application in large-scale removal of Cr(VI) in aqueous solution.

Investigations of the structural evolution of electrospun nanofibers using atomic force microscopy

Stepwise structural evolution of nanofibers through electrospinning was captured by AFM imaging. Nanofiber evolution exhibited five characteristic structures in turn: columns, plates, micropores, bumps and smooth surface. Based on our results and previous studies, these five stages are discussed in detail and the mechanism of nanofiber formation is proposed. In addition, the drug incorporation process of blend-electrospun nanofibers was shown vividly and clearly by AFM. It suggested that drugs could be completely incorporated into nanofibers by blend-electrospinning if proper polymers and drugs were chosen. Furthermore, the effects of solution properties on nanofiber structural evolution were also studied systematically.

A redox responsive controlled release system using mesoporous silica nanoparticles capped with Au nanoparticles

A novel redox responsive controlled release system based on the host-guest interaction between ferrocene modified mesoporous silica nanoparticles (MSN-Fc) and beta-cyclodextrin modified gold nanoparticles (Au@CD) was developed. FITC was used as the release molecule and it was loaded into the pores of MSN-Fc. With the addition of oxidant (H2O2), oxidized ferrocene leaves the hydrophobic cavity of b-CD, resulting in cargo controlled release. Due to the structural properties of the modified MSN, the continuously slow release behavior showed the prospect to be a sustained drug delivery system. This novel redox responsive system possessed stimuli-responsive controlled release and sustained release properties, and therefore has potential applications in sustained and targeted drug delivery.