title: New calix[4]arene derivatives as ionophores in polymeric membrane electrodes for Ag(I): comparative selectivity studies and detection of DNA hybridization.
abstract: Four calix[4]arene derivatives containing various donor atoms and different topology (L1-L4) have been synthesized and used as neutral ionophores to fabricate silver ion selective electrodes (Ag-ISEs) which were characterized in terms of their potentiometric selectivities and complex formation constants. The ionophore L2 having two nitrogen and two sulfur donors showed stronger interactions with Ag(+) and the highest selectivity coefficient towards Ag(+). The best membrane electrode was prepared from L2 and used to fabricate silver ion selective microelectrodes (Ag-ISμEs) which could detect silver ions in 1000 μL samples with detection limit around 1 μM using sodium ion microelectrodes as a pseudo reference electrode. Such potentiometric measurement was then applied to detect DNA hybridization on a gold substrate, employing immobilized lipoic acid-modified pyrrolidinyl PNA (Lip-acpcPNA) as a probe. The hybridization between the neutral Lip-acpcPNA probe and DNA target led to a negatively charged surface that could bind positively charged silver nanoparticles (AgNPs(+)) via electrostatic interactions. The hybridization signal was observed by dissolution of the electrostatically adsorbed AgNPs(+) with hydrogen peroxide. Excellent discrimination of complementary from single mismatched and non-complementary DNA targets was achieved under non-stringent conditions. The detection limit of DNA was 0.2 μM in 1000 μL samples.
authors.affiliation: Department of Chemistry, Faculty of Science, Chulalongkorn University, Bangkok 10330, Thailand.
authors.forename: Wanwisa
authors.initials: W
authors.lastname: Janrungroatsakul
authors.forename: Tirayut
authors.initials: T
authors.lastname: Vilaivan
authors.forename: Chotima
authors.initials: C
authors.lastname: Vilaivan
authors.forename: Sarayut
authors.initials: S
authors.lastname: Watchasit
authors.forename: Chomchai
authors.initials: C
authors.lastname: Suksai
authors.forename: Wittaya
authors.initials: W
authors.lastname: Ngeontae
authors.forename: Wanlapa
authors.initials: W
authors.lastname: Aeungmaitrepirom
authors.forename: Thawatchai
authors.initials: T
authors.lastname: Tuntulani
mesh_terms: D001483:Base Sequence; D047250:Calixarenes / Q000737:chemistry*; D004247:DNA / Q000737:chemistry*; D004566:Electrodes; D008567:Membranes, Artificial; D046529:Microscopy, Electron, Transmission; D009693:Nucleic Acid Hybridization; D010636:Phenols / Q000737:chemistry*; D011108:Polymers / Q000737:chemistry*; D012834:Silver / Q000737:chemistry*
chemical_list: D008567:Membranes, Artificial; D010636:Phenols; D011108:Polymers; C121325:calix(4)arene; D047250:Calixarenes; D012834:Silver; D004247:DNA