Molecular separation, hydrogels

H. Feil, Y.H. Bae, J. Feijen and S.W. Kim, Molecular separation by thermosensitive hydrogel membranes, J. Membr. Sci., 1991, 64, 283 N. Kyaman, D. Kazan, A. Eearslan, O. Okay and B.M. Baysal, Structure and protein separation efficiency of poly(Y-isopropylacrylamide) gels Effect of synthesis conditions, J. Appl. Polym. Sci., 1998, 67, 805. 

Feil et al. have demonstrated the molecular separation of solutes of three different sizes by using a poly(NIPAAm-co-butyl methacrylate)(BMA) copolymer hydrogel membrane at several temperatures (18,19). The diffusion of urinine (MW 300) and dextran (MW 4400) was found to follow the... 

Figure 20.10. Amphiphilic ionic self-complementary peptides. This class of peptides has 16 amino acids, c. 5 nm in size, with an alternating polar and non-polar pattern. They form stable (3-strand and 3-sheet structures thus, the side chains partition into two sides, one polar and the other non-polar. They undergo self-assembly to form nanofibers with the non-polar residues inside positively and negatively charged residues form complementary ionic interactions, like a checkerboard. These nanofibers form interwoven matrices that further form a scaffold hydrogel with a very high water content ( 99.5%). The simplest peptide scaffold may form compartments to separate molecules into localized places where they can not only have high concentration, but also form a molecular gradient, one of the key prerequisites for prebiotic molecular evolution.

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