Fluorescent single-stranded DNA-based assay for detecting unchelated Gadolinium(III) ions in aqueous solution

• Published in: Analytical and bioanalytical chemistry Vol. 408; no. 15; pp. 4121 - 4131
• Main Authors: Edogun, Osafanmwen, Nguyen, Nghia Huu, Halim, Marlin
• Format: Journal Article
• Language: English
• Published: Berlin/Heidelberg Springer Berlin Heidelberg 01-06-2016; Springer; Springer Nature B.V
• Subjects: Analysis; Analytical Chemistry; Aqueous solutions; Assaying; Biochemistry; Characterization and Evaluation of Materials; Chelating Agents - chemistry; Chemical properties; Chemistry; Chemistry and Materials Science; Contrast agents; Contrast Media - chemistry; Design engineering; DNA; DNA, Single-Stranded - chemistry; Europium; Fluorescence; Food Science; Gadolinium; Gadolinium - chemistry; Hydrogen-Ion Concentration; Infrared spectroscopy; Ions; Laboratory Medicine; Ligands; Magnetic resonance imaging; Mathematical analysis; Monitoring/Environmental Analysis; Nanostructure; Research Paper; Safety; SELEX Aptamer Technique - methods; Sensors; Terbium; Toxicity; United States; Fluorogenic sensor; Lanthanide ion sensor; Chemical sensor; Aqueous Gd(III) ions
• ISSN: 1618-2642; 1618-2650
• DOI: 10.1007/s00216-016-9503-2

The main concern pertaining to the safety of Gadolinium(III)-based contrast agents (GBCAs) is the toxicity caused by the unchelated ion, which may be inadvertently present in the solution due most commonly to excess unreacted starting material or dissociation of the complexes. Detecting the aqueous free ion during the synthesis and preparation of GBCA solutions is therefore instrumental in ensuring the safety of the agents. This paper reports the development of a sensitive fluorogenic sensor for aqueous unchelated Gadolinium(III) (Gd(III)). Our design utilizes single-stranded oligodeoxynucleotides with a specific sequence of 44 bases as the targeting moiety. The fluorescence-based assay may be run at ambient pH with very small amounts of samples in 384-well plates. The sensor is able to detect nanomolar concentration of Gd(III), and is relatively unresponsive toward a range of biologically relevant ions and the chelated Gd(III). Although some cross-reactivity with other trivalent lanthanide ions, such as Europium(III) and Terbium(III), is observed, these are not commonly found in biological systems and contrast agents. This convenient and rapid method may be useful in ascertaining a high purity of GBCA solutions.
Graphical abstract
Fluorescent aptamer-based assay for detecting unchelated Ln(III) ions in aqueous solution