title: Effects of salt concentrations of the aqueous peptide-amphiphile solutions on the sol-gel transitions, the gelation speed, and the gel characteristics.
abstract: Hydrogels made of peptide amphiphiles (PA) have attracted a lot of interest in biomedical fields. Considering the applications of PA hydrogels, the control of the gelation speed and the gel characteristics is essential to predominantly determine the usefulness and practicability of the hydrogels. In this work, the effects of the salt concentrations using sodium dihydrogenorthophosphate (NaH2PO4) on the sol-gel transition behaviors, especially the gelation speed and the gel characteristics of the designed PA (C16-W3K) hydrogels in aqueous solution were discussed. It was found that the original solution state before rheological testing was independent of the salt concentration, which was confirmed by observing the self-assembly structures and the peptide secondary structures of PA through transmission electron microscopy (TEM) and circular dichroism spectroscopy (CD). The PA solutions with different salt concentrations, however, presented a profound difference in the gelation speed and the gel characteristics: the solution exhibited higher gelation speeds and higher mechanical properties at higher salt concentrations. Concurrently, the density, the length of wormlike micelles, and the conformational ratio of β-sheets to α-helices in the equilibrium PA solutions all increased with the increase in the salt concentrations.
authors.affiliation: Department of Mechanical Engineering, Keio University , 3-14-1 Hiyoshi, Kohoku-ku, Yokohama 223-8522, Japan.
authors.forename: Takahiro
authors.initials: T
authors.lastname: Otsuka
authors.forename: Tomoki
authors.initials: T
authors.lastname: Maeda
authors.forename: Atsushi
authors.initials: A
authors.lastname: Hotta
mesh_terms: D002942:Circular Dichroism; D020100:Hydrogels / Q000737:chemistry*; D010455:Peptides / Q000737:chemistry*; D044367:Phase Transition; D010710:Phosphates / Q000737:chemistry*; D017433:Protein Structure, Secondary; D012996:Solutions / Q000737:chemistry; D014783:Viscosity
chemical_list: D020100:Hydrogels; D010455:Peptides; D010710:Phosphates; D012996:Solutions; C018279:sodium phosphate