Colorimetric metal ion binding of catechol-based coatings inspired by melanin and molecular imprinting
Catechol-containing biomolecules and related synthetic materials are of interest for a broad range of applications. Our group has been interested in the potential of eumelanin, a catechol-containing biomaterial and the black-to-brown pigment in humans, and synthetic eumelanin analogues for water purification applications. In an attempt to apply the strategy of molecular imprinting towards lead-binding synthetic eumelanin coatings, we developed a PbO2-mediated synthesis that was subsequently tested with a number of catechols in addition to the eumelanin and polydopamine monomers l-dopa and dopamine. Although this strategy did not provide significant improvements in affinity or selectivity, we found that the PbO2-mediated oxidative polymerisation of 1,2-dihydroxybenzene generates a coating that darkens visibly upon binding Pb2+ and other metal ions. Oxidative polymerisation of catechol with sodium periodate also yields a coating with this colorimetric response. Of eight metal ions tested, the coatings are most responsive to Pb2+ and Cu2+, as analysed by quantitative colorimetry. With further optimisation, these coatings could prove useful for the colorimetric sensing of metal ions.
Belitsky, J.M., D.S. Lye, H.R. Gittleman, T.A. Gorlin, A.N. Gorham, C.A. Moore, M.B. Chaves, and M.Z. Ellowitz. 2014. “Colorimetric metal ion binding of catechol-based coatings inspired by melanin and molecular imprinting.” Supramolecular Chemistry 26(3-4): 233-244.
Taylor & Francis
Chemistry and Biochemistry
Special issue: Eighth International Symposium of Macrocyclic and Supramolecular Chemistry (ISMSC-8)
Catechol, Melanin, Molecular imprinting, Colorimetric, Metal ions