New poly(aryleneethynylene)s as optical active platforms in biosensing. Selective fluorescent detection of Hg(II) obtained by the use of aminoacidic groups anchored on conjugated backbones

Newly synthesized poly(aryleneethynylene)s carrying substituents such as leucine, glycine and methionine have been prepared and tested for their ability to bind Hg(II) ions. Binding resulted in strong quenching of the fluorescence emission of all the compounds tested. A comparative study of the quenching efficiency by Hg(II) was then carried out in a flow injection system. Quenching efficiency was amplified in the polymeric material because of the so-called “wire effect” that is observed with organic conducting polymers. Under the experimental conditions used, detection limits are in the 50–100 ppb range. The selectivity for Hg(II) is remarkable in that a series of other divalent cations did not give any measurable effect, a slight response being observed for methylmercury only. The materials hold promise for selective determination of Hg(II) ion.[...]