Superparamagnetic poly(styrene-divinylbenzene-glycidyl methacrylate) (Pst-DVB-GMA) microparticles were prepared via a modified suspension polymerization process. A magnetic fluid was first prepared by a chemical co-precipitation method. Then magnetic microparticles were produced by mixing the monomers and the magnetic fluid with water in the presence of a stabilizer poly(vinyl pyrrolidone) (PVP) to form a suspension, and finally benzoyl peroxide was added to initiate the co-polymerization. The morphology and magnetic properties of the microparticles were examined by TEM and VSM. The spherically shaped microparticles, with a size range of 4 to 7 μm, showed distinct superparamagnetic characteristics. XRD was used to investigate the structure of the magnetite particles dispersed in the polymer matrix. The microparticles with epoxy groups on their surface can be applied directly to the separation of biomolecules.
A novel method for preparation of magnetic polymer microspheres by spraying suspension polymerization (SSP) was developed. Relatively uniform magnetic poly(methyl methacrylate) microspheres were prepared by the spraying suspension polymerization (SSP) using methyl methacrylate (MMA) as monomer, divinylbenzene (DVB) as cross-linking agent, benzoyl peroxide (BPO) as initiator and polyvinyl alcohol (PVA) as stabilizer in the presence of hydrophobic Fe3O4 magnetic fluid. The microspheres prepared were modified by surface chemical reaction. The magnetic properties and morphology of the microspheres were examined by SEM and VSM respectively. The active functional groups of microspheres were examined by infrared spectra. The results showed that microspheres with saturation magnetization of 16.8 emu/g showed distinct superparamagnetic characteristics and the magnetic microspheres with a size of 10 μm were relatively uniform.
YANG Chengli GUAN Yueping XING Jianmin LIU Junguo AN Zhentao LIU Huizhou
Rhodococcus erythropolis LSSE8-1 is a newly isolated biodesulfurizaion strain from the soil of Chishui gas field, Guizhou Province, China. The analysis of its metabo-lism product shows that the strain is a kind of biocatalyst able to oxidize dibenzothiophene (DBT) to 2-hydroxydi- phenyl (HBP), and therefore the sulfur in DBT is selectively removed. By using DBTO2 (dibenzothiophene 5,5-dioxide) as substrate, both DBT and HBP are found in the culture, which shows that the reaction from DBT to DBTO2 is re-versible in the cell. While using 0.5 mmol/L DBT as control, 0.01—0.4 mmol/L DBTO2 shows poisonous effect to the cell, which will explain why there is no DBTO2 accumulation in the process of biodesulfurization. After treatment by lysozme, the plasmid DNA of the strain is isolated by alkaline method to be used as the template of PCR reaction. Three dsz gene fragments of 1.3, 1.0 and 1.2 kb respectively were amplified. Each fragment is ligate with PGEM-T vector, and cloned into E. coli. DH5. The clone DNA is sequenced and the result shows that dsz related genes are highly conservative. The identities of dszA and dszB with respect to IGTS8 are 100%, and the identity of dszC with that of IGTS8 is 99%.
GOU Zhongxuan, LUO Mingfang, LI Xin, XING Jianmin & LIU Huizhou Laboratory of Separation Science and Engineering, State Key Laboratory of Biochemical Engineering, Institute of Process Engineering, Chinese Academy of Sciences, Beijing 100080, China Correspondence should be addressed to Liu Huizhou (e-mail: hzliu@ home.ipe.ac.cn)
