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Volume 166, 2013
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The influence of the kinetics of self-assembly on the properties of dipeptide hydrogels

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Abstract

We discuss the effect of the kinetics of pH change on the mechanical properties of dipeptide hydrogels. Data from other peptide-based low molecular weight gelator (LMWG) systems suggest that the rheological properties are often highly dependent on the assembly rate. To examine kinetics here, we have used the hydrolysis of glucono-δ-lactone (GdL). The hydrolysis of GdL to gluconic acid results in a decrease in pH, the rate of which is temperature sensitive. Hence, we can adjust the rate of pH decrease, whilst achieving the same absolute final pH. Our data shows that at all temperatures the rheological profile is very similar, with an increase to a plateau, followed by a second increase in moduli, despite very different kinetics of assembly. Surprisingly, the final mechanical properties are very similar in all cases. We also show that the structures formed at the plateau can be accessed by adjusting the pH using CO2. By carefully balancing the pKa of the gelator with the pH achievable using CO2, flexible hydrogel membranes can be formed as opposed to a bulk gel. The rheological characteristics of the membranes are typical of a highly entangled polymer network. These membranes can be rigidified by post-addition of GdL to further lower the pH.

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Publication details

The article was received on 12 Jul 2013, accepted on 19 Jul 2013 and first published on 22 Jul 2013


Article type: Paper
DOI: 10.1039/C3FD00104K
Citation: Faraday Discuss., 2013,166, 101-116
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    The influence of the kinetics of self-assembly on the properties of dipeptide hydrogels

    A. Z. Cardoso, A. E. Alvarez Alvarez, B. N. Cattoz, P. C. Griffiths, S. M. King, W. J. Frith and D. J. Adams, Faraday Discuss., 2013, 166, 101
    DOI: 10.1039/C3FD00104K

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