Jump to main content
Jump to site search

Issue 12, 2014
Previous Article Next Article

Ultra-sensitive pH control of supramolecular polymers and hydrogels: pKa matching of biomimetic monomers

Author affiliations

Abstract

Achieving self-assembly in water with small molecules that disassemble in response to minimal changes in environmental conditions is important for the development of many promising materials. We report the most sensitive possible pH control of a supramolecular polymer assembly – demonstrated with hydrogel-forming monomers that mimic nucleic acid base pairing. Bidirectional pH-responsive supramolecular polymers are formed upon the self-assembly of three monomers with two pKa-matched recognition units (one acidic and one basic). These supramolecular assemblies are most stable when the pH equals the pKa of the monomers, but disassemble in response to small pH changes near neutrality (exhibiting the theoretical limit for pH-dependent stability). At pH 7 a hydrogel forms in solutions that are 0.7% by weight in monomer, however, the hydrogel dissolves at pH 6 and pH 8. Additionally, we show that hydrogel stability is finely tuned by employing monomer mixtures that frustrate formation of insoluble aggregates. These results illustrate the advantages of using pKa-matched recognition elements and polymer heterogeneity in the development of responsive materials. Finally, these same recognition elements have recently been proposed as possible ancestors of the current bases of RNA. In this context, the assemblies described here might also provide clues to how the first genetic polymers were driven between states of base pairing and non-base pairing by periodic changes in environmental pH.

Graphical abstract: Ultra-sensitive pH control of supramolecular polymers and hydrogels: pKa matching of biomimetic monomers

Back to tab navigation

Supplementary files

Publication details

The article was received on 22 Jul 2014, accepted on 24 Sep 2014 and first published on 24 Sep 2014


Article type: Edge Article
DOI: 10.1039/C4SC02182G
Author version available: Download Author version (PDF)
Citation: Chem. Sci., 2014,5, 4681-4686
  •   Request permissions

    Ultra-sensitive pH control of supramolecular polymers and hydrogels: pKa matching of biomimetic monomers

    B. J. Cafferty, R. R. Avirah, G. B. Schuster and N. V. Hud, Chem. Sci., 2014, 5, 4681
    DOI: 10.1039/C4SC02182G

Search articles by author

Spotlight

Advertisements