3D networks from self-assembling ionic-complementary octa-peptides

Abstract

The self-assembly and gelation properties of a set of four octo-peptides AEAEAKAK, AEAKAEAK, FEFEFKFK and FEFKFEFK based on alanine (A), phenylalanine (F), lysine (K) and glutamic acid (E) were investigated via small angle neutron scattering (SANS). The SANS experiments suggest that AEAKAEAK peptide does not self-assemble in solution while AEAEAKAK form rod-like structure i.e.: fibres with a radius of ∼3.3 nm. The latter peptide does not form a gel suggesting that the fibres do not aggregate and form a three-dimensional network. On the other hand FEFEFKFK and FEFKFEFK peptides were found to form gels for concentrations higher than ∼7 mg ml-1. Below the critical gelation concentration these peptides were also found to form fibrillar structures with smaller average radii of ∼1.7 nm. Above the critical gelation concentration a scattering maximum is observed in the scattered intensity curve. From the position of the maximum a rough estimation of the mesh size of the gel network could be derived and was found to vary between 15 and 30 nm depending on the gel concentration. Copyright © 2007 WILEY-VCH Verlag GmbH & Co. KGaA.