Magnetic-separation-assisted magnetic relaxation switching (MRS) assay based on the concentration change of magnetic nanoparticles switches has been designed for bacteria, biological macromolecules, and small molecules detection because of its better analysis performance. As one of the most hazardous pollutants and highly dangerous elements, mercury ion (Hg2+) was employed as a model to further investigate the applicability of nanoparticle switches concentration change-based MRS assay mode for detecting metal ions in this study. The principle is based on the specific and strong interaction between mercury ion with the thymine-thymine(T-T) mismatch in double-stranded DNA duplexes by employing oligonucleotide functionalized magnetic nanoparticle as magnetic capture probe and MRS signal probe, respectively. The result shows that magnetic nanoparticles concentration-dependent MRS sensing mode could be facile applied to detect metal ion of Hg2+ in tap water, lake water and serum with wider detection range and higher accuracy. The as-presented magnetic-separation-assisted MRS assay of Hg2+ in complicated samples shows potential application values for Hg2+ assay in clinical and environmental monitoring, which broadens its application.
Keywords: magnetic nanoparticles; magnetic relaxation switches; magnetic separation; mercury ion; oligonucleotide.