title: Spiropyran-based optical approaches for mercury ion sensing: improving sensitivity and selectivity via cooperative ligation interactions using cysteine.
abstract: Spiropyrans are an attractive starting point in design of optical approaches for metal ions sensing. However, the high background in aqueous solution and non-specific chelation of the spiropyran with heavy metal ions has hindered their application as reliable sensors for environmental and biological species. Here, we report on a new spiropyran-based approach for sensitive and selective sensing of Hg(2+) in aqueous solution, based on cooperative ligation interactions among the spiropyran probe, an intermediate, cysteine, and the metal ion. To test the feasibility of this design, three spiropyran scaffolds, L1-L3, with different ligation functions at the 8'-position were examined as model systems. The results demonstrate that by using cysteine, a potential ligand of Hg(2+), the spiropyran could detect 1.0x10(-7) M Hg(2+) in aqueous solution. Due to the specific metal-amino acid interaction, the approach exhibits selective response toward Hg(2+) over other metal ions and anions, although possible interference from Cu(2+) has to be considered at the high level of the metal ion. This approach has been used for the determination of Hg(2+) in water samples containing potential interferents with satisfactory recovery.
authors.affiliation: Beijing National Laboratory for Molecular Sciences, College of Chemistry and Molecular Engineering, Peking University, Beijing 100871, China.
authors.forename: Na
authors.initials: N
authors.lastname: Shao
authors.forename: Xiadi
authors.initials: X
authors.lastname: Gao
authors.forename: Hao
authors.initials: H
authors.lastname: Wang
authors.forename: Ronghua
authors.initials: R
authors.lastname: Yang
authors.forename: Winghong
authors.initials: W
authors.lastname: Chan
mesh_terms: D001578:Benzopyrans / Q000737:chemistry*; D002412:Cations / Q000737:chemistry; D003545:Cysteine / Q000737:chemistry*; D006863:Hydrogen-Ion Concentration; D007211:Indoles / Q000737:chemistry*; D008628:Mercury / Q000032:analysis*; D009574:Nitro Compounds / Q000737:chemistry*; D015203:Reproducibility of Results; D013056:Spectrophotometry, Ultraviolet / Q000379:methods*; D014874:Water Pollutants, Chemical / Q000032:analysis*
chemical_list: D001578:Benzopyrans; D002412:Cations; D007211:Indoles; D009574:Nitro Compounds; D014874:Water Pollutants, Chemical; C088184:spiropyran; D008628:Mercury; D003545:Cysteine