Heavy metal ion hydrogelation of a self-assembling peptideviacysteinyl chelation

Abstract

Hydrogel materials are finding use in heavy metal ion detection and remediation. MBHP is a twenty-residue peptide capable of undergoing hydrogelation in response to heavy metal ion binding. The unstructured peptide binds monomethylarsonous acid, Pb²⁺, Zn²⁺, Cd²⁺ or Hg²⁺ and subsequently folds into an amphiphilic β-hairpin that rapidly self-assembles into a β-sheet rich fibrillar network as shown by CD spectroscopy and transmission electron microscopy. LCMS shows that MBHP binds metal ions with a 1 : 1 stoichiometry. Oscillatory rheology indicates that moderately rigid hydrogels are formed as a result of metal ion binding, peptide folding and ultimate self-assembly with storage moduli (G′) ranging from ∼1000–4000 Pa.