Roy, Sangita and Javid, Nadeem and Frederix, Pim and Lamprou, Dimitrios and Urquhart, Andrew and Hunt, Neil and Halling, Peter and Ulijn, Rein (2012) Dramatic specific ion effect in supramolecular hydrogels. Chemistry - A European Journal, 18 (37). pp. 11723-11731.Full text not available in this repository. (Request a copy from the Strathclyde author)
We report on a pronounced specific-ion effect on the intermolecular and chiral organization, supramolecular structure formation, and resulting materials properties for a series of low molecular weight peptide-based hydrogelators, observed in the presence of simple inorganic salts. This effect was demonstrated using aromatic short peptide amphiphiles, based on fluorenylmethoxycarbonyl (Fmoc). Gel-phase materials were formed due to molecular self-assembly, driven by a combination of hydrogen bonding and pi-stacking interactions. Pronounced morphological changes were observed by atomic force microscopy (AFM) for Fmoc-YL peptide, ranging from dense fibrous networks to spherical aggregates, depending on the type of anions present. The gels formed had variable mechanical properties, with G' values between 0.8 kPa and 2.4 kPa as determined by rheometry. Spectroscopic analysis provided insights into the differential mode of self-assembly, which was found to be dictated by the hydrophobic interactions of the fluorenyl component, with comparable H-bonding patterns observed in each case. The efficiency of the anions in promoting the hydrophobic interactions and thereby self-assembly was found to be consistent with the Hofmeister anion sequence. Similar effects were observed with other hydrophobic peptides, Fmoc-VL and Fmoc-LL. The effect was found to be less pronounced for a less hydrophobic peptide, Fmoc-AA. To get more insights into the molecular mechanism, the effect of anions on sol-gel equilibrium was investigated, which indicates the observed changes result from the specific-ion effects on gels structure, rather than on the sol-gel equilibrium. Thus, we demonstrate that, by simply changing the ionic environment, structurally diverse materials can be accessed providing an important design consideration in nanofabrication via molecular self-assembly.
|Keywords:||supramolecular hydrogels, ions, hydrogels, specific ion-effect, intermolecular, chiral organization, supramolecular structure formation, materials properties, low molecular weight, peptide-based hydrogelators, Chemistry, Physics, Pharmacy and materia medica|
|Subjects:||Science > Chemistry|
Science > Physics
Medicine > Pharmacy and materia medica
|Department:||Faculty of Science > Pure and Applied Chemistry|
Faculty of Science > Physics
Faculty of Science > Strathclyde Institute of Pharmacy and Biomedical Sciences
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|Depositing user:||Pure Administrator|
|Date Deposited:||06 Aug 2012 15:56|
|Last modified:||10 Dec 2013 10:00|
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