title: Linking micellar structures to hydrogelation for salt-triggered dipeptide gelators.
abstract: Some functionalised dipeptides can form hydrogels when salts are added to solutions at high pH. We have used surface tension, conductivity, rheology, optical, confocal and scanning electron microscopy, (1)H NMR and UV-Vis spectroscopy measurements to characterise fully the phase behaviour of solutions of one specific gelator, 2NapFF, at 25 °C at pH 10.5. We show that this specific naphthalene-dipeptide undergoes structural transformations as the concentration is increased, initially forming spherical micelles, then worm-like micelles, followed by association of these worm-like micelles. On addition of a calcium salt, gels are generally formed as long as worm-like micelles are initially present in solution, although there are structural re-organisations that occur at lower concentrations, allowing gelation at lower than expected concentration. Using IR and SANS, we show the differences between the structures present in the solution and hydrogel phases.
authors.affiliation: Department of Chemistry, University of Liverpool, Crown Street, Liverpool, L69 7ZD, UK. d.j.adams@liverpool.ac.uk.
authors.forename: Andre Zamith
authors.initials: AZ
authors.lastname: Cardoso
authors.affiliation: Department of Chemistry, University of Liverpool, Crown Street, Liverpool, L69 7ZD, UK. d.j.adams@liverpool.ac.uk.
authors.forename: Laura L E
authors.initials: LL
authors.lastname: Mears
authors.affiliation: Department of Pharmaceutical, Chemical and Environmental Science, University of Greenwich, Medway Campus, Central Avenue, Chatham Maritime, Kent ME4 4TB, UK.
authors.forename: Beatrice N
authors.initials: BN
authors.lastname: Cattoz
authors.affiliation: Department of Pharmaceutical, Chemical and Environmental Science, University of Greenwich, Medway Campus, Central Avenue, Chatham Maritime, Kent ME4 4TB, UK.
authors.forename: Peter C
authors.initials: PC
authors.lastname: Griffiths
authors.affiliation: Institut Laue-Langevin, Large Scale Structures Group, 71 Avenue des Martyrs, CS 20156, F-38042 Grenoble CEDEX 9, France.
authors.forename: Ralf
authors.initials: R
authors.lastname: Schweins
authors.affiliation: Department of Chemistry, University of Liverpool, Crown Street, Liverpool, L69 7ZD, UK. d.j.adams@liverpool.ac.uk.
authors.forename: Dave J
authors.initials: DJ
authors.lastname: Adams
mesh_terms: D004151:Dipeptides / Q000737:chemistry*; D020100:Hydrogels / Q000737:chemistry*; D006863:Hydrogen-Ion Concentration; D008823:Micelles; D009281:Naphthalenes / Q000737:chemistry; D012492:Salts / Q000737:chemistry*
chemical_list: D004151:Dipeptides; D020100:Hydrogels; D008823:Micelles; D009281:Naphthalenes; D012492:Salts; C031721:naphthalene