Membrane Modification assemblies

Based on these observations, Wang and Caruso [237] have described an effective method for the fabrication of robust zeolitic membranes with three-dimensional interconnected macroporous (1.2 pm in diameter) stmctures from mesoporous silica spheres previously seeded with silicalite-1 nanoparticles subjected to a conventional hydrothermal treatment. Subsequently, the zeolite membrane modification via the layer-by-layer electrostatic assembly of polyelectrolytes and catalase on the 3D macroporous stmcture results in a biomacromolecule-functionalized macroporous zeolitic membrane bioreactor suitable for biocatalysts investigations. The enzyme-modified membranes exhibit enhanced reaction stability and also display enzyme activities (for H2O2 decomposition) three orders of magnitude higher than their nonporous planar film counterparts assembled on silica substrates. Therefore, the potential of such structures as bioreactors is enormous. 

To understand the modifications made to polysaccharides in PEMs applications, a cursory knowledge of fuel cells is necessary. A fuel cell is an electrochemical cell that converts chemical fuel into electrical energy. Figure 3.4 shows a simplified view of a proton conductive fuel cell. The main components in a PEM fuel cell are catalyst layers, gas diffusion layers and the PEM itself. These three components comprise the membrane electrode assembly. The catalyst... 

Mechanism of the polyimide (PI) membrane modification by diethanolamine (DEA) and the self-assembly ofTiOj nanoparticles on the DEA-modified surface of the PI membrane. (Adapted from Mansourpanah etaL, 2009.)... 

The biogenesis of membranes is thus a complex process about which much remains to be learned. One indication of the complexity involved is to consider the number of posttranslational modifications that membrane proteins may be subjected to prior to attaining their mamre state. These include proteolysis, assembly... 

The function of many adaptor proteins is closely linked with the cell membrane or with the cytoskeleton. The occurrence of PH domains and myristoyl modifications suggests that adaptor proteins are involved in particular in coordination and assembly of signal complexes on the iimer side of the ceU membrane. 

In this section we describe briefly the two models for inserting integral proteins into cell membranes with special emphasis on the protease(s)-catalyzed hydrolytic modification of these proteins associated with the membrane assembly process. These two models are (1) self assembly following translation of the proteins and (2) coupling of translation with insertion of the protein into the membrane. 

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