Metal complexation hydrogels

II) complexation that could be further strengthened by additional covalent cross-linking of the methacrylate moieties [176], This approach served to form hydrogels with both supramolecular and covalent cross-Unks that are stimuli responsive to acid, base, peroxides, and heat, all of which lead to ligand dissociation and metal complex degradation, thereby entailing more loosely cross-linked materials. 

Redox hydrogels containing coordinated metal complexes that have a formal potential which enables mediated electron transfer to and from interfacial electroactive biomolecules are highly attractive for biosensor development [11]. For example, redox hydrogels are the only known... 

Polymer metal complex formation of different polyvinylpyridines in solution, in hydrogels and at interfaces were investigated [83]. In aqueous solution linear or crosslinked polyvinylpyridines in the interaction with H2PtCl6 results in reduced viscosities and reduces swelling coefficients, respectively. Complexation leads to molecular bridges and folding of the polymer. Film formation was observed at the interface of poly(2-vinylpyridine) dissolved in benzene and metal salts dissolved in water. 

Figure 3 Schematic illustration of a hybrid hydrogel system—genetically engineered coiled-coil protein domains used to crosslink synthetic water-soluble polymers. Divalent transition metal ions are shown to form complexes with nitrogen-oxygen-donor ligands on the synthetic polymer side chains and the terminal histidine residues in the coiled coils.

Tatykhanova GS, Kudaibergenov SE. (2008) Controlled release of local anesthetic drug richlocaine from the pH- and thermosensitive hydrogels-copolymers of N-isopropylacrilamide and acrylic acid. New smart materials via metal mediated macromolecular engineering from complex to nanostructures. Antalya, Turkey, 1-12 September 2008. 

In contrast to these approaches based on nonspecific interactions, Zhang and coworkers described a molecularly imprinted hydrogel based on the ther-moresponsive PNIPAM [184], This hydrogel was prepared by copolymerization of a metal chelate monomer iV-(4-vinyl)-benzyl iminodiacetic acid, which formed a coordination complex with the template protein in the presence of Cu ions, A-isopropylacrylamide, acrylamide, and IV.lV-methylenebisacrylamide as crosslinker. The interaction of the imprinted thermoresponsive hydrogel with the protein could be switched between coordination effects and electrostatic attraction by addition or omission of Cu ions. Furthermore, this imprinted hydrogel allowed switching of lysozyme adsorption by changing the temperature. 

Kojima Y., Isobe T., Senna M. Shinohara T., Ono S., Sumiyama K., Suzuki K. Mechanism of complex formation between metallic Al and titania hydrogel via a mechanical route. J. Mater. Res. 1996 11 1305-9. 

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