Facile Fabrication of Porous ZnS and ZnO Films by Coaxial Electrospinning for Highly Efficient Photodegradation of Organic Dyes.

Porous ZnS and ZnO nano-crystal films were fabricated via a three-step procedure. First, Zn(CH3 COO)2 /Silk Fibroin nanofiber mats were prepared by coaxial electrospinning. Second, Zn(CH3 COO)2 /Silk Fibroin mats were immersed in NaS solution to react with S2- to obtain ZnS/Silk Fibroin nanofiber mats. Finally, ZnO porous films were prepared by calcination of ZnS/Silk Fibroin composite mat at 600°C in air atmosphere. When ZnS/Silk Fibroin mats were calcinated in nitrogen, ZnS/Carbon composite mats were obtained accordingly. The resulting porous films were fully characterized. The ZnO porous films were the aggregation of ZnO nano-crystal with hexagonal wurtzite structure. The seize of ZnO was estimated in the range of 10-20 nm. Both of the ZnS and ZnO nano-crystal films exhibited high photocatalytic activities for the photodegradation of Methylene blue and Rhodamine B. It was also found that ZnO porous films are better than ZnS/Carbon nanofiber mats. In addition, photocatalysis of a real wastewater sample from a printing and dyeing company was conducted. The ZnO porous films exhibited excellent performance to treat the real samples. Moreover, the porous ZnO nano-crystal photocatalyst could easily be recycled without notable loss of catalysis ability.

Expression of EGFP-spider dragline silk fusion protein in BmN cells and larvae of silkworm showed the solubility is primary limit for dragline proteins yield.

Spider dragline silk is a unique fibrous protein with combination of tensile strength and elasticity, but the isolation of large amount of silk from spiders is not feasible. In this paper, we used a newly established Bac-to-Bac/BmNPV Baculovirus expression system to express the recombinant spider (Nephila clavata) dragline silk protein (MaSp1) fused EGFP in BmN cells and larvae of silkworm. A 70 kDa fusion protein was visualized after rBacmid/BmNPV/drag infection by SDS-PAGE and immunoblotting analysis. Fusion protein expressed in the BmN cells probably occupied five percent of the cell total protein; In a silkworm larva, approximately 6 mg fusion proteins were expressed. Solubility analysis of the expressed spider dragline silk protein indicated that 60% fusion protein is insoluble. EGFP fluorescence showed that fusion protein is tend to form aggregate by self assemblage. The results indicated the solubility is the primary limit for spider dragline proteins yield. It also suggested that directly produce fibrous spider silk in the secreting-silk organs of the transgenic silkworm larvae might be a better method.