Isoporous separation membranes have received considerable attention because of the high-resolution performance and energy-saving characteristics. Isoporous membranes prepared by the breath figure method rely on special substrates such as water and ice because solid substrates such as polyethylene terephthalate films, which are widely used in commercial processes, often lead to nonthrough pores. In this work, it is found that highly ordered through-pore membranes can be fabricated on hydrophilic glass surface when using polymers that are able to form ordered membranes at low concentrations. On the basis of this finding, a facile strategy is proposed to fabricate isoporous membranes on various solid substrates by introducing a water-soluble polymer interlayer. The multifunctional interlayer promotes the spreading of membrane-forming solutions, enables the formation of through pores, and simplifies the transfer to macroporous supports to form composite membranes. The versatility of the proposed strategy is verified by using different substrates including highly hydrophobic polytetrafluoroethylene film and using different water-soluble polymers as the interlayer. Furthermore, the high-resolution separation performance of the isoporous composite membranes has been demonstrated by the filtration of yeasts under gravitational pressure.
Bojuan Hao,Kaige Wang,Yukun Zhou,Chaofan Sui,Lei Wang,Ren Bai,Zhaojin Yang
DNA molecular compaction/decompaction is of great significance for the exploration of basic life processes, the research of biomedical and genetic engineering, and so forth. However, the detailed mechanism of DNA compaction/decompaction caused by surfactants remains an open and challenging problem that has not been fully solved so far. In this paper, a sort of novel solid substrate, nanoPAA-ZnCl2-AuLs, with good stability and high sensitivity, was prepared by a self-assembly method. Based on this substrate, the surface-enhanced Raman scattering (SERS) technology was employed to investigate characteristics of interactions between DNA molecules and surfactants at a single molecular level. SERS spectra of calf thymus DNA (ctDNA), cetyl trimethyl ammonium bromide (CTAB), and sodium dodecyl sulfate (SDS) with a concentration as low as 10–9 M, and SERS spectra of ctDNA–CTAB and ctDNA–CTAB–SDS composites were collected, respectively. The interactions between ctDNA and surfactants were analyzed by changes in SERS spectra, for example, disappearances and appearances of SERS bands and relative changes of peak intensity, in which CTAB resulted in the compaction of the DNA molecule while SDS induced the decompaction of the ctDNA–CTAB complex. Moreover, UV–visible spectrophotometry was employed to demonstrate the compaction/decompaction of ctDNA molecules caused by surfactants. The local binding modes of ctDNA molecules and surfactant molecules were expounded. This work will be helpful for understanding biological processes such as DNA compaction and recombination within nucleus or/and cells and for the development of gene therapy technologies.
危险品化学品经营许可证（带存储）