title: Differentially selective chemosensor with fluorescence off-on responses on Cu(2+) and Zn(2+) ions in aqueous media and applications in pyrophosphate sensing, live cell imaging, and cytotoxicity.
abstract: A new benzoyl hydrazone based chemosensor R is synthesized by Schiff base condensation of 2,6-diformyl-4-methylphenol and phenyl carbohydrazide and acts as a highly selective fluorescence sensor for Cu(2+) and Zn(2+) ions in aqueous media. The reaction of R with CuCl2 or ZnCl2 forms the corresponding dimeric dicopper(II) [Cu2(R)(CH3O)(NO3)]2(CH3O)2 (R-Cu(2+)) and dizinc(II) [Zn2(R)2](NO3)2 (R-Zn(2+)) complexes, which are characterized, as R, by conventional techniques including single-crystal X-ray analysis. Electronic absorption and fluorescence titration studies of R with different metal cations in a CH3CN/0.02 M HEPES buffer medium (pH = 7.3) show a highly selective binding affinity only toward Cu(2+)and Zn(2+) ions even in the presence of other commonly coexisting ions such as Na(+), K(+), Mg(2+), Ca(2+), Mn(2+), Fe(2+), Fe(3+), Co(2+), Ni(2+), Cd(2+), and Hg(2+). Quantification of the fluorescence titration analysis shows that the chemosensor R can indicate the presence of Cu(2+)and Zn(2+) even at very low concentrations of 17.3 and 16.5 ppb, respectively. R-Zn(2+) acts as a selective metal-based fluorescent sensor for inorganic pyrophosphate ion (PPi) even in the presence of other common anions such as F(-), Cl(-), Br(-), I(-), CH3COO(-), CO3(2-), HCO3(-), N3(-), SO4(2-), PPi, AMP, ADP, and ATP in an aqueous medium. The propensity of R as a bioimaging fluorescent probe to detect Cu(2+) and Zn(2+) ions in human cervical HeLa cancer cell lines and their cytotoxicity against human cervical (HeLa), breast cancer (MCF7), and noncancer breast epithelial (MCF10a) cells have also been investigated. R-Cu(2+) shows better cytotoxicity and sensitivity toward cancer cells over noncancer cells than R and R-Zn(2+) under identical conditions, with the appearance of apoptotic bodies.
authors.affiliation: Centro de Química Estrutural, Complexo I, Instituto Superior Técnico, Universidade de Lisboa , Avenida Rovisco Pais, 1049-001 Lisboa. Portugal.
authors.forename: Sellamuthu
authors.initials: S
authors.lastname: Anbu
authors.forename: Rajendran
authors.initials: R
authors.lastname: Ravishankaran
authors.forename: M Fátima C
authors.initials: MF
authors.lastname: Guedes da Silva
authors.forename: Anjali A
authors.initials: AA
authors.lastname: Karande
authors.forename: Armando J L
authors.initials: AJ
authors.lastname: Pombeiro
mesh_terms: D000255:Adenosine Triphosphate / Q000737:chemistry; D045744:Cell Line, Tumor; D002470:Cell Survival / Q000187:drug effects*; D002477:Cells / Q000648:ultrastructure*; D003300:Copper / Q000737:chemistry*; D011756:Diphosphates / Q000737:chemistry*; D005453:Fluorescence; D006367:HeLa Cells; D006801:Humans; D008670:Metals / Q000737:chemistry; D012996:Solutions; D014867:Water; D015032:Zinc / Q000737:chemistry*
chemical_list: D011756:Diphosphates; D008670:Metals; D012996:Solutions; D014867:Water; D003300:Copper; D000255:Adenosine Triphosphate; D015032:Zinc