Fig. 4.

Collapse of metallothionein in the presence of heavy metals can also result in significant decreases in the hydrogel volume. (A) Structural representations of metallothionein before and after metal binding. (B) A novel chemistry was used to end-functionalize the protein and incorporate it as a hydrogel cross-linker. (C) The resulting hydrogels underwent measurable volume decreases in the presence of heavy metals, such as Cd²⁺. (Reprinted with permission from Esser-Kahn et al.⁴², copyright 2008 American Chemical Society).