Dually Cross‐Linked Supramolecular Hydrogel as Surface Plasmon Resonance Sensor for Small Molecule Detection

: Dually cross-linked supramolecular hydrogels (DCSH) are designed to show responsive properties while maintaining the gel structure by introducing two different kinds of cross-links. This is realized by utilizing a photo-cross-linker for permanent cross-linking and β-cyclodextrin (β-CD) and ferrocene (Fc) as host-guest recognition pair. The DCSH shows increased swelling in the presence of the small target molecule adamantane amine (Ada). Ada can break the non-covalent bonding between β-CD and Fc through competitive molecular guest interaction with β-CD. By using a combination of surface plasmon resonance and optical waveguide spectroscopy, it is possible to use this behavior to construct a reversible sensor for specific small molecule detection.