Membrane preparation/modification

If not noted elsewhere, all data correspond to the preparation of a 10 x 12 cm cellulose membrane (96-well plate size). For larger membranes preparation of related amounts of reagents is required. If we write about the use of amino acids, it should always include the use of other organic building blocks (e.g., PNA monomers, peptoidic elements, heterocycles) (22,23), which can be used under spot synthesis conditions. Here we describe only the basic procedures for spot synthesis of linear peptides. For the synthesis of modified peptides, such as cyclization or side-chain modifications, see ref. (24). 

There are many different modifications of the method, early technology used membrane preparations, modem methods use solubilized receptors and receptor of constructs which enable fast signal detection. 

Membranes prepared by the majority of the established methods have limitations in their pore sizes. To make membranes with finer pore diameters suitable for more demanding separation and membrane reactor applications, a widely practiced technique is to modify the pores or the surface of an existing membrane structure which has already been made. This encompasses a variety of techniques. Some of them are based on gas or vapor phase reactions. Others modifications occur in liquid phase. Some progress having pore diameters in the molecular sieving range has been made. 

Van Praag, W., V. Zaspalis, K. Keizer, J.G. van Ommen, J.R. Ross and AJ. Burggraaf, 1989, Preparation, modification and micropoious stnicture of alumina and titania ceramic membrane systems, in Pioc. 1st Int Conf. Inorg. Membr., Montpellier, France, p.397. 

In 1999, Brasseur-Tilmant [56] presented a work dealing with modification of macroporous alumina media by TiOi particles deposition using supercritical isopropanol. The aim was to prepare inorganic membranes for cross-fiow filtration. Anatase particles were deposited on plane alumina support after thermal decomposition of titanium alkoxide precursors. A slight infiltrated zone was observed and a pore size reduction was achieved from 110 to 5 nm, leading to obtain fine ultrafiltration membranes. The main problem was to control the reaction at the membrane interface and not in the porosity, and moreover, this process was suitable for mbular membrane preparation. 

R.S.A. de Lange, J.H.A. Hekkink, K. Keizer and A.J. Burggraaf, Formation and characterisation of supported microporous ceramic membranes prepared by sol-gel modification techniques. /. Membr. Sci., 99 (1995) 57-75. 

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