Complexing of heavy metals with DNA and new bioaffinity method of their determination based on amperometric DNA-based biosensor.
The immobilized single-stranded DNA (ssIDNA) has been found to be a very effective biospecific analytical reagent when used in a newly developed bioaffinity method of the determination of heavy metals based on the amperometric DNA-based biosensor. This has been concluded from the comparative study of the complexing of heavy metals with double-stranded DNA, single-stranded DNA, and ssIDNA, using Fe(III) and Cu(II) as a model (metal/nucleotide ratio and stability constants are maximum for ssIDNA), from the study of adsorption of Fe(III), Cu(II), Pb(II), and Cd(II) on nitrocellulose membranes, containing single-stranded DNA, and from the determination of their binding constants with ssIDNA. According to these data, the chosen heavy metals can be lined up in a series of binding strengths with ssIDNA: Cu(II) > Pb(II) > Fe(III) > Cd(II). The method of the determination of heavy metals is based on biospecific preconcentration of metal ions on the biosensor followed by the destruction of DNA-metal complexes with ethylenediaminetetraacetate and voltammogram recording has been proposed. The lower detection limits are 4.0 x 10(-11), 1.0 x 10(-10), 1.0 x 10(-9), and 5.0 x 10(-9) M for Cu(II), Pb(II), Cd(II), and Fe(III), respectively. The heavy metals have been assayed in multicomponent environmental and biological systems such as natural and drinking water, milk, and blood serum samples.
Babkina
S S
SS
Chemical Faculty, Kazan State University, Kremlevskaya Street, 18, Kazan 420008, Russia. sofia-babkina@mail.ru
Ulakhovich
N A
NA
D015374:Biosensing Techniques / Q000379:methods*; D004247:DNA / Q000737:chemistry*; D007477:Ions / Q000737:chemistry; D019216:Metals, Heavy / Q000032:analysis* / Q000097:blood / Q000737:chemistry*
D007477:Ions; D019216:Metals, Heavy; D004247:DNA