Photo-Induced Charge Transfer on Pt/Bi2WO6 Composite Photocatalysts.

Pt/Bi2WO6 composite photocatalysts were prepared by a facile photoreduction method. Pt nanoparticles with an average size of 5-8 nm were successfully deposited on the surface of Bi2WO6 microspheres and the photocatalytic activity of Bi2WO6 was greatly improved by Pt nanoparticles. The photo-induced charge transfer properties of samples were studied by means of surface photovoltage (SPV) and transient photovoltage (TPV) techniques, giving an insight into the intrinsic reasons of the improvement in photocatalytic activity. The SPV and TPV results revealed that the deposited Pt nanoparticles could trap photo-induced electrons and then largely enhance the separation efficiency of photo-induced charge carriers.

[Construction and expression of spap/A eukaryotic expression plasmid of Streptococcus mutans in mammalian cells].

PURPOSE: The study is aimed to evaluate the expression of recombinant plasmid pVAX1-spap/A of surface protein antigen A of Streptococcus mutans in mammalian cells COS-7. METHODS: The eukaryotic plasmid carrying encoding gene of spap/A of Streptococcus mutans was constructed and the plasmid introduced into COS-7 cells by lipofectamine reagent. The transient expressed protein was detected by immunochemistry technique in COS-7 cells. RESULTS: Positive expression was detected in plasma of the cells which were transfected with recombinant plasmid pVAX1-spap/A. The cells which were transfected with pVAX1 were negative. CONCLUSIONS: Spap/A can translate and express in COS-7 cells after transfected with recombinant plasmid pVAX1-spap/A. The expressed protein locates in the plasma and the protein is able to combine with anti-spap/A antibody. The expressed protein has the antigenicity and recombinant plasmid pVAX1-spap/A is a candidate vaccine.

[Construction of gtfB/CAT eukaryotic expression plasmid of Streptococcus mutans in mammalian cells].

PURPOSE: The study aimed to evaluate the expression of recombinant plasmid pVAX1- gtfB/CAT in mammalian COS-7 cells. METHODS: The eukaryotic plasmid carrying encoding gene of gtfB/CAT of Streptococcus mutans was constructed and introduced into COS-7 cells by lipofectamine reagent. The transient protein expression was detected by immunochemistry technique in COS-7 cells. RESULTS: The positive expression of gefB/CAT was detected in plasma of the cells which were transfected with recombinant plasmid pVAX1- gtfB/CAT. The cells which were transfected with pVAX1 were negative for gtfB/CAT expression. CONCLUSIONS: GtfB/CAT can be translated and expressed in COS-7 cells after transfected with recombinant plasmid pVAX1- gtfB/CAT. The expressed protein is located in the plasma and the protein is able to combine with anti- gtfB/CAT antibody. The expressed protein has the antigenicity and recombinant plasmid pVAX1- gtfB/CAT is a candidate vaccine.Supported by Key Research Project of Bureau of Education of Guizhou Province (Grant No.2004119).