title: Sol-gel transition of charged fibrils composed of a model amphiphilic peptide.
abstract: We characterized the sol-gel transition of positively charged fibrils composed of the model amphiphilic peptide RADARADARADARADA (RADA 16-I) using a combination of microscopy, light scattering, microrheology and rheology techniques, and we investigated the dependence of the hydrogel formation on fibril concentration and ionic strength. The peptide is initially present as a dispersion of short rigid fibrils with average length of about 100 nm. During incubation, the fibrils aggregate irreversibly into longer fibrils and fibrillar aggregates. At peptide concentrations in the range 3-6.5 g/L, the fibrillar aggregates form a weak gel network which can be destroyed upon dilution. Percolation occurs without the formation of a nematic phase at a critical peptide concentration which decreases with increasing ionic strength. The gel structure can be well described in the frame of the fractal gel theory considering the network as a collection of fibrillar aggregates characterized by self-similar structure with a fractal dimension of 1.34.
authors.affiliation: Institute for Chemical and Bioengineering, Department of Chemistry and Applied Biosciences, ETH Zurich, Zurich, Switzerland.
authors.forename: Marta
authors.initials: M
authors.lastname: Owczarz
authors.affiliation: Institute of Food, Nutrition and Health, Food and Soft Materials Science, ETH Zurich, Switzerland.
authors.forename: Sreenath
authors.initials: S
authors.lastname: Bolisetty
authors.affiliation: Institute of Food, Nutrition and Health, Food and Soft Materials Science, ETH Zurich, Switzerland.
authors.forename: Raffaele
authors.initials: R
authors.lastname: Mezzenga
authors.affiliation: Institute for Chemical and Bioengineering, Department of Chemistry and Applied Biosciences, ETH Zurich, Zurich, Switzerland. Electronic address: paolo.arosio@chem.ethz.ch.
authors.forename: Paolo
authors.initials: P
authors.lastname: Arosio
mesh_terms: D005782:Gels; D007700:Kinetics; D018625:Microscopy, Atomic Force; D008956:Models, Chemical; D010455:Peptides / Q000737:chemistry*; D012212:Rheology
chemical_list: D005782:Gels; D010455:Peptides
keywords: Aggregation; Fibrillar hydrogel; Fractal gel model; Gelation; Peptide self-assembly