Dissecting the effect of anions on Hg2+ detection using a FRET based DNA probe.
Many biosensors have been developed to detect Hg(2+) using thymine-rich DNA. While sensor response to various cations is often studied to demonstrate selectivity, the effect of anions has been largely overlooked. Anions may compete with DNA for metal binding and thus produce a false negative result. Anions cannot be added alone; the cation part of a salt may cause DNA compaction and other effects, obscuring the role of anions. We find that the sensitivity of a FRET-based Hg(2+) probe is independent of Na(+) concentration. Therefore, by using various sodium salts, any change in sensitivity can be attributed solely to the effect of anions. Halide salts, sulfides, and amines are strong inhibitors; anions containing oxo or hydroxyl groups (e.g. nitrate, sulfate, phosphate, carbonate, acetate, and citrate) do not interfere with Hg(2+) detection even at 100 mM concentration. Mercury hydrolysis and its diffusion into polypropylene containers can also strongly affect the detection results. We conclude that thymine-rich DNA should be useful for Hg(2+) detection in many environmental water samples.
Department of Chemistry, Waterloo Institute for Nanotechnology, University of Waterloo, 200 University Avenue West, Waterloo, Ontario N2L 3G1, Canada.
Mehmet Murat
MM
Kiy
Ahmed
A
Zaki
Arsalsan Beg
AB
Menhaj
Azadeh
A
Samadi
Juewen
J
Liu
D000838:Anions / Q000737:chemistry*; D004247:DNA / Q000737:chemistry; D015342:DNA Probes / Q000737:chemistry*; D031541:Fluorescence Resonance Energy Transfer; D008628:Mercury / Q000032:analysis*; D013941:Thymine / Q000737:chemistry; D014874:Water Pollutants, Chemical / Q000737:chemistry
D000838:Anions; D015342:DNA Probes; D014874:Water Pollutants, Chemical; D004247:DNA; D008628:Mercury; D013941:Thymine