title: An Aptamer-based Sensor for Unchelated Gadolinium(III).
abstract: A method for determining the presence of unchelated trivalent gadolinium ion (Gd3+) in aqueous solution is demonstrated. Gd3+is often present in samples of gadolinium-based contrast agents as a result of incomplete reactions between the ligand and the ion, or as a dissociation product. Since the ion is toxic, its detection is of critical importance. Herein, the design and usage of an aptamer-based sensor (Gd-sensor) for Gd3+are described. The sensor produces a fluorescence change in response to increasing concentrations of the ion, and has a limit of detection in the nanomolar range (~100 nM with a signal-to-noise ratio of 3). The assay may be run in an aqueous buffer at ambient pH (~7 - 7.4) in a 384-well microplate. The sensor is relatively unreactive toward other physiologically relevant metal ions such as sodium, potassium, and calcium ions, although it is not specific for Gd3+over other trivalent lanthanides such as europium(III) and terbium(III). Nevertheless, the lanthanides are not commonly found in contrast agents or the biological systems, and the sensor may therefore be used to selectively determine unchelated Gd3+in aqueous conditions.
authors.affiliation: Department of Chemistry and Biochemistry, California State University, East Bay.
authors.forename: Osafanmwen
authors.initials: O
authors.lastname: Edogun
authors.affiliation: Department of Chemistry and Biochemistry, California State University, East Bay.
authors.forename: Tracy Y
authors.initials: TY
authors.lastname: Chan
authors.affiliation: Department of Chemistry and Biochemistry, California State University, East Bay.
authors.forename: Nghia H
authors.initials: NH
authors.lastname: Nguyen
authors.affiliation: Department of Chemistry and Biochemistry, California State University, East Bay.
authors.forename: Anthony
authors.initials: A
authors.lastname: Luu
authors.affiliation: Department of Chemistry and Biochemistry, California State University, East Bay; marlin.halim@csueastbay.edu.
authors.forename: Marlin
authors.initials: M
authors.lastname: Halim
mesh_terms: D052157:Aptamers, Nucleotide / Q000737:chemistry*; D003287:Contrast Media; D005682:Gadolinium / Q000032:analysis*; D017736:Ion-Selective Electrodes; D014874:Water Pollutants, Chemical / Q000032:analysis*
chemical_list: D052157:Aptamers, Nucleotide; D003287:Contrast Media; D014874:Water Pollutants, Chemical; D005682:Gadolinium